Communication system, base station device, and communication terminal device

Abstract

To prevent a base station device from being occupied by a specific communication terminal device and from being unable to accommodate other communication terminal devices.SOLUTION: A communication system includes a base station device and a plurality of communication terminal devices capable of wireless communication with the base station device. The base station device notifies communication terminal devices present within a range where communication is possible of, as system information, operational restriction information relating to restricted operations of restricted terminal devices, which are some communication terminal devices whose operations are restricted, among the plurality of communication terminal devices. When the communication terminal devices that have been notified of the operational restriction information determines that their own devices are the restricted terminal devices, the communication terminal devices operate in accordance with the operational restriction information. Information for changing the operational restriction information is transmitted using a paging message. The operational restriction information is information for restricting the transmission of an RRC (Radio Resource Control) connection request signal from the restricted terminal devices to the base station device.SELECTED DRAWING: Figure 14

Description

Technical Field

[0001] The present invention relates to a communication system that performs wireless communication between a plurality of communication terminal devices and a base station device, and a base station device and a communication terminal device included in the communication system.

Background Art

[0002] Among communication systems called the third generation, the W-CDMA (Wideband Code division Multiple Access) system has been in commercial service in Japan since 2001. In addition, by adding a channel for packet transmission (High Speed-Downlink Shared Channel: HS-DSCH) to the downlink (individual data channel, individual control channel), the HSDPA (High Speed Downlink Packet Access) service that realizes further speeding up of data transmission using the downlink has been started. Furthermore, in order to further speed up data transmission in the uplink direction, the HSUPA (High Speed Uplink Packet Access) system has also been put into service. W-CDMA is a communication system defined by 3GPP (3rd Generation Partnership Project), a standardization organization for mobile communication systems, and the standard document of Release 8 has been compiled.

[0003] In addition, in 3GPP, as a communication system different from W-CDMA, a new communication system called Long Term Evolution (LTE) for the radio section and System Architecture Evolution (SAE) for the overall system configuration including the core network (also simply referred to as the network) is being studied. This communication system is also called a 3.9G (3.9 Generation) system.

[0004] In LTE, the access method, radio channel configuration, and protocol are completely different from those of the current W-CDMA (HSDPA / HSUPA). For example, in terms of the access method, while W-CDMA uses Code Division Multiple Access, LTE uses OFDM (Orthogonal Frequency Division Multiplexing) in the downlink and SC-FDMA (Single Career Frequency Division Multiple Access) in the uplink. Also, the bandwidth can be selected for each base station from 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, and 20 MHz, whereas it is 5 MHz for W-CDMA. Additionally, LTE does not include circuit switching like W-CDMA and is only a packet communication system.

[0005] Since LTE uses a new core network different from the core network (General Packet Radio Service: GPRS) of W-CDMA to configure the communication system, it is defined as an independent radio access network separate from the W-CDMA network. Therefore, to distinguish it from the W-CDMA communication system, in the LTE communication system, the base station that communicates with the mobile terminal (User Equipment: UE) is called eNB (E-UTRAN NodeB), and the base station controller (Radio Network Controller) that exchanges control data and user data with multiple base stations is called EPC (Evolved Packet Core) or aGW (Access Gateway).

[0006] In this LTE communication system, unicast services and E-MBMS services (Evolved Multimedia Broadcast Multicast Service) are provided. The E-MBMS service is a broadcast-type multimedia service and may also be simply referred to as MBMS. High-capacity broadcast content such as news, weather forecasts, and mobile broadcasts is transmitted to multiple mobile terminals. This is also called a point-to-multipoint service.

[0007] Current decisions regarding the overall architecture in the LTE system in 3GPP are described in Non-Patent Document 1 (Chapter 4). The overall architecture will be described with reference to FIG. 1. FIG. 1 is an explanatory diagram showing the configuration of an LTE-based communication system. In FIG. 1, if the control protocol for the mobile terminal 101, such as RRC (Radio Resource Control), and the user plane, such as PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), and PHY (Physical layer), terminate at the base station 102, then the E-UTRAN (Evolved Universal Terrestrial Radio Access) is composed of one or more base stations 102.

[0008] The base station 102 schedules and transmits paging signals (also referred to as paging messages) notified from the MME (Mobility Management Entity) 103. The base stations 102 are connected to each other through the X2 interface. Also, the base station 102 is connected to the EPC (Evolved Packet Core) through the S1 interface. More specifically, the base station 102 is connected to the MME (Mobility Management Entity) 103 through the S1_MME interface and to the S-GW (Serving Gateway) 104 through the S1_U interface.

[0009] The MME 103 distributes paging signals to multiple or single base stations 102. Also, the MME 103 performs mobility control in the idle state. The MME 103 manages the tracking area list when the mobile terminal is in the idle state and the active state.

[0010] The S-GW 104 transmits and receives user data with one or more base stations 102. The S-GW 104 serves as a local mobility anchor point during handover between base stations. There is also a P-GW (PDN Gateway) in the EPC, which performs packet filtering for each user and assigns UE-ID addresses, etc.

[0011] The control protocol RRC between the mobile terminal 101 and the base station 102 performs functions such as broadcast, paging, and RRC connection management. The states of the base station and the mobile terminal in RRC are RRC_Idle and RRC_CONNECTED. In RRC_IDLE, PLMN (Public Land Mobile Network) selection, system information (SI) broadcast, paging, cell re-selection, mobility, etc. are carried out. In RRC_CONNECTED, the mobile terminal has an RRC connection and can perform data transmission and reception with the network. Additionally, handover (HO), measurement of neighboring cells, etc. are carried out.

[0012] Regarding the current decisions on the frame configuration in the LTE system in 3GPP described in Non-Patent Document 1 (Chapter 5), it will be explained with reference to FIG. 2. FIG. 2 is an explanatory diagram showing the configuration of a radio frame used in an LTE communication system. In FIG. 2, one radio frame is 10 ms. The radio frame is divided into 10 subframes of equal size. Each subframe is divided into 2 slots of equal size. The first and sixth subframes of each radio frame contain downlink synchronization signals (SS). The synchronization signal includes a primary synchronization signal (P-SS) and a secondary synchronization signal (S-SS).

[0013] Multiplexing of channels for MBSFN (Multimedia Broadcast multicast service Single Frequency Network) and channels other than MBSFN is performed in subframe units. MBSFN Transmission is a simulcast transmission technique realized by transmitting the same waveform from a plurality of cells simultaneously. MBSFN transmissions from a plurality of cells in an MBSFN Area appear to be a single transmission to a mobile terminal. MBSFN is a network that supports such MBSFN transmissions. Hereinafter, a subframe for MBSFN transmission is referred to as an MBSFN subframe.

[0014] Non-Patent Document 2 describes a signaling example at the time of allocation of an MBSFN subframe. FIG. 3 is an explanatory diagram showing the configuration of an MBSFN frame. In FIG. 3, a radio frame including an MBSFN subframe is allocated for each radio Frame Allocation Period. An MBSFN subframe is a subframe allocated for MBSFN in a radio frame defined by a radio Frame Allocation Period and a radio Frame Allocation Offset, and is a subframe for transmitting multimedia data. A radio frame satisfying the following formula (1) is a radio frame including an MBSFN subframe.

[0015] SFN mod radioFrameAllocationPeriod = radioFrameAllocationOffset …(1) The allocation of MBSFN subframes is carried out with 6 bits. The leftmost bit defines the MBSFN allocation for the second subframe (#1). The second bit is for the third subframe (#2), the third bit is for the fourth subframe (#3), the fourth bit is for the seventh subframe (#6), the fifth bit is for the eighth subframe (#7), and the sixth bit is for the ninth subframe (#8). When the bit indicates "1", it shows that the corresponding subframe is allocated for MBSFN.

[0016] The current decisions regarding the channel configuration in the LTE system in 3GPP are described in Non-Patent Document 1 (Chapter 5). It is assumed that the same channel configuration as that in non-CSG cells is used in CSG (Closed Subscriber Group cell) cells. The physical channel will be described with reference to FIG. 4. FIG. 4 is an explanatory diagram for explaining the physical channels used in the LTE communication system.

[0017] In FIG. 4, the Physical Broadcast Channel (PBCH) 401 is a downlink channel transmitted from the base station 102 to the mobile terminal 101. The BCH transport block is mapped to 4 subframes within a 40 ms interval. There is no explicit signaling for the 40 ms timing. The Physical Control Format Indicator Channel (PCFICH) 402 is transmitted from the base station 102 to the mobile terminal 101. The PCFICH notifies the mobile terminal 101 from the base station 102 about the number of OFDM symbols used for PDCCHs. The PCFICH is transmitted for each subframe.

[0018] The Physical Downlink Control Channel (PDCCH) 403 is a downlink channel transmitted from the base station 102 to the mobile terminal 101. The PDCCH notifies the resource allocation of the DL-SCH (Downlink Shared Channel, one of the transport channels shown in Fig. 5 below) and the PCH (Paging Channel, one of the transport channels shown in Fig. 5), and HARQ information regarding the DL-SCH. The PDCCH carries an Uplink Scheduling Grant. The PDCCH carries an Ack (Acknowledgement) / Nack (Negative Acknowledgement), which is a response signal for uplink transmission. The PDCCH is also called an L1 / L2 control signal.

[0019] The Physical Downlink Shared Channel (PDSCH) 404 is a downlink channel transmitted from the base station 102 to the mobile terminal 101. The PDSCH has the DL-SCH (Downlink Shared Channel), which is a transport channel, and the PCH, which is also a transport channel, mapped thereto. The Physical Multicast Channel (PMCH) 405 is a downlink channel transmitted from the base station 102 to the mobile terminal 101. The PMCH has the MCH (Multicast Channel), which is a transport channel, mapped thereto.

[0020] The Physical Uplink Control Channel (PUCCH) 406 is an uplink channel transmitted from the mobile terminal 101 to the base station 102. The PUCCH carries an Ack / Nack which is a response signal to a downlink transmission. The PUCCH carries a CQI (Channel Quality Indicator) report. The CQI is quality information indicating the quality of received data or the communication channel quality. The PUCCH also carries a Scheduling Request (SR). The Physical Uplink Shared Channel (PUSCH) 407 is an uplink channel transmitted from the mobile terminal 101 to the base station 102. A UL-SCH (uplink shared channel which is one of the transport channels shown in Fig. 5) is mapped to the PUSCH.

[0021] The Physical Hybrid ARQ Indicator Channel (PHICH) 408 is a downlink channel transmitted from the base station 102 to the mobile terminal 101. The PHICH carries an Ack / Nack which is a response to an uplink transmission. The Physical Random Access Channel (PRACH) 409 is an uplink channel transmitted from the mobile terminal 101 to the base station 102. The PRACH carries a random access preamble.

[0022] The downlink reference signal is a symbol known as a mobile communication system. As a measurement of the physical layer of a mobile terminal, there is a measurement of the received power of the reference symbol (Reference Symbol Received Power: RSRP).

[0023] The transport channel described in Non-Patent Document 1 (Chapter 5) will be described with reference to FIG. 5. FIG. 5 is an explanatory diagram for explaining the transport channels used in the LTE communication system. FIG. 5(A) shows the mapping between the downlink transport channel and the downlink physical channel. FIG. 5(B) shows the mapping between the uplink transport channel and the uplink physical channel.

[0024] Regarding the downlink transport channel, the Broadcast Channel (BCH) is notified to the entire coverage area of the base station (cell). The BCH is mapped to the Physical Broadcast Channel (PBCH).

[0025] For the Downlink Shared Channel (DL-SCH), retransmission control by Hybrid ARQ (HARQ) is applied. The DL-SCH can be notified to the entire coverage area of the base station (cell). The DL-SCH supports dynamic or semi-static resource allocation. Semi-static resource allocation is also called Persistent Scheduling. The DL-SCH supports Discontinuous Reception (DRX) of the mobile terminal for power consumption reduction of the mobile terminal. The DL-SCH is mapped to the Physical Downlink Shared Channel (PDSCH).

[0026] The Paging Channel (PCH) supports DRX of the mobile terminal to enable low power consumption of the mobile terminal. The PCH requires notification to the entire coverage area of the base station (cell). The PCH is mapped to a physical resource such as the Physical Downlink Shared Channel (PDSCH) that can be dynamically used for traffic.

[0027] The Multicast Channel (MCH) is used for notification to the entire coverage area of a base station (cell). The MCH supports the SFN synthesis of MBMS services (MTCH and MCCH) in multi-cell transmission. The MCH supports semi-static resource allocation. The MCH is mapped to the PMCH.

[0028] For the Uplink Shared Channel (UL-SCH), retransmission control by Hybrid ARQ (HARQ) is applied. The UL-SCH supports dynamic or semi-static resource allocation. The UL-SCH is mapped to the Physical Uplink Shared Channel (PUSCH).

[0029] The Random Access Channel (RACH) shown in Figure 5(B) is limited to control information. The RACH has a risk of collision. The RACH is mapped to the Physical Random Access Channel (PRACH).

[0030] The HARQ will be described. HARQ is a technology that improves the communication quality of a transmission path through a combination of Automatic Repeat reQuest and Forward Error Correction. It has the advantage that error correction functions effectively by retransmission even for a transmission path where the communication quality changes. In particular, it is also possible to obtain further quality improvement by combining the reception result of the first transmission and the reception result of the retransmission at the time of retransmission.

[0031] An example of the retransmission method will be described. At the receiving side, if the received data cannot be correctly decoded, in other words, if a CRC (Cyclic Redundancy Check) error occurs (CRC = NG), the receiving side transmits a "Nack" to the transmitting side. The transmitting side that receives the "Nack" retransmits the data. At the receiving side, if the received data can be correctly decoded, in other words, if no CRC error occurs (CRC = OK), the receiving side transmits an "Ack" to the transmitting side. The transmitting side that receives the "Ack" transmits the next data.

[0032] As an example of the HARQ method, there is Chase Combining. Chase Combining is a method in which the same data is transmitted in the first transmission and the retransmission, and the gain is improved by combining the data of the first transmission and the retransmission in the retransmission. This is based on the idea that even if there are errors in the first transmission data, it also contains some accurate parts, and by combining the accurate parts of the first transmission data and the retransmission data, data can be transmitted with higher accuracy. Also, as another example of the HARQ method, there is IR (Incremental Redundancy). IR is a method that increases the redundancy, and by transmitting parity bits in the retransmission, the redundancy is increased in combination with the first transmission, and the quality is improved by the error correction function.

[0033] The logical channel (Logical channel, sometimes hereinafter referred to as "logical channel") described in Non-Patent Document 1 (Chapter 6) will be described with reference to FIG. 6. FIG. 6 is an explanatory diagram for explaining the logical channel used in the LTE communication system. FIG. 6(A) shows the mapping between the downlink logical channel and the downlink transport channel. FIG. 6(B) shows the mapping between the uplink logical channel and the uplink transport channel.

[0034] The Broadcast Control Channel (BCCH) is a downlink channel for broadcast system control information. The BCCH, which is a logical channel, is mapped to the Broadcast Channel (BCH), which is a transport channel, or to the Downlink Shared Channel (DL-SCH).

[0035] The Paging Control Channel (PCCH) is a downlink channel for transmitting paging information and changes in system information. The PCCH is used when the network does not know the cell location of the mobile terminal. The PCCH, which is a logical channel, is mapped to the Paging Channel (PCH), which is a transport channel.

[0036] The Common Control Channel (CCCH) is a channel for transmission control information between the mobile terminal and the base station. The CCCH is used when the mobile terminal does not have an RRC connection with the network. In the downlink direction, the CCCH is mapped to the Downlink Shared Channel (DL-SCH), which is a transport channel. In the uplink direction, the CCCH is mapped to the Uplink Shared Channel (UL-SCH), which is a transport channel.

[0037] The Multicast Control Channel (MCCH) is a downlink channel for one-to-many transmission. The MCCH is used for transmitting MBMS control information for one or several MTCHs from the network to the mobile terminal. The MCCH is used only by mobile terminals receiving MBMS. The MCCH is mapped to the Multicast Channel (MCH), which is a transport channel.

[0038] The Dedicated Control Channel (DCCH) is a channel that transmits dedicated control information between a mobile terminal and a network on a one-to-one basis. The DCCH is used when the mobile terminal has an RRC connection. On the uplink, the DCCH is mapped to the Uplink Shared Channel (UL-SCH), and on the downlink, it is mapped to the Downlink Shared Channel (DL-SCH).

[0039] The Dedicated Traffic Channel (DTCH) is a channel for one-to-one communication to an individual mobile terminal for the transmission of user information. The DTCH exists on both the uplink and the downlink. On the uplink, the DTCH is mapped to the Uplink Shared Channel (UL-SCH), and on the downlink, it is mapped to the Downlink Shared Channel (DL-SCH).

[0040] The Multicast Traffic channel (MTCH) is a downlink channel for the transmission of traffic data from the network to mobile terminals. The MTCH is a channel used only by mobile terminals during MBMS reception. The MTCH is mapped to the Multicast Channel (MCH).

[0041] GCI stands for Global Cell Identity. In LTE, Long Term Evolution Advanced (LTE-A) described later, and Universal Mobile Telecommunication System (UMTS), Closed Subscriber Group (CSG) cells are introduced. CSG will be described below (see Section 3.1 of Non-Patent Document 3). A CSG (Closed Subscriber Group) cell is a cell in which the operator has identified available subscribers (hereinafter sometimes referred to as a "cell for specific subscribers").

[0042] A specified subscriber is permitted to access one or more cells of a PLMN (Public Land Mobile Network). One or more cells to which the specified subscriber is permitted to access are referred to as "CSG cell(s)". However, there are access restrictions to the PLMN. A CSG cell is a part of a PLMN that broadcasts a unique CSG identity (CSG ID) and indicates "TRUE" in the CSG Indication. Members of a pre-registered and permitted subscriber group access the CSG cell using the CSG-ID which is access permission information.

[0043] The CSG-ID is broadcast by the CSG cell or cells. There are multiple CSG-IDs in the mobile communication system. And the CSG-ID is used by a mobile terminal (UE) to facilitate access by CSG-related members.

[0044] The location tracking of a mobile terminal is performed in units of an area consisting of one or more cells. The location tracking is to track the location of the mobile terminal even in the standby state and enable calling (the mobile terminal is incoming called). The area for this location tracking of the mobile terminal is called a tracking area.

[0045] A CSG White List is a list that may be stored in a USIM (Universal Subscriber Identity Module) in which all CSG IDs of the CSG cells to which a subscriber belongs are recorded. The CSG White List may also be referred to as an Allowed CSG List.

[0046] The service types of a mobile terminal in the standby state will be described below (see Section 4.3 of Non-Patent Document 3). The service types of a mobile terminal in the standby state include limited service (also referred to as restricted service), normal service, and operator service. Limited service refers to emergency calls, ETWS (Earthquake and Tsunami Warning System), and CMAS (Commercial Mobile Alert System) on an acceptable cell, which will be described later. Normal service (also referred to as regular service or normal service) refers to public services on an appropriate cell, which will be described later. Operator service refers to services only for the operator on a reserved cell, which will be described later.

[0047] The "suitable cell" will be described below. The "suitable cell" is a cell on which a UE may camp to receive normal service. Such a cell shall meet the following conditions (1) and (2).

[0048] (1) The cell is part of the selected PLMN or the registered PLMN, or a PLMN in the "Equivalent PLMN list".

[0049] (2) Based on the latest information provided by the NAS (Non-Access Stratum), it shall further meet the following conditions (a) to (d). (a) The cell is not a barred cell. (b) The cell is part of a tracking area (TA) that is not part of the "list of prohibited LAs for roaming". In that case, the cell shall meet the above (1). (c) The cell meets the cell selection evaluation criteria. (d) For a cell that is identified by the System Information (SI) as a Closed Subscriber Group (CSG) cell, the CSG-ID shall be part of the UE's "CSG WhiteList" (i.e., included in the UE's CSG WhiteList).

[0050] The "Acceptable cell" is described below. This is a cell on which the UE may camp in order to receive restricted services. Such a cell shall meet all of the following requirements.

[0051] (1) The cell shall not be a barred cell (also referred to as a barred cell). (2) The cell shall meet the cell selection evaluation criteria.

[0052] A "barred cell" is indicated in the system information. A "reserved cell" is indicated in the system information.

[0053] "Camping on a cell" means that the UE has completed the cell selection or cell reselection process and has selected a cell to monitor the system information and paging information.

[0054] In 3GPP, base stations called Home-NodeB (Home-NB; HNB) and Home-eNodeB (Home-eNB; HeNB) are being considered. The HNB in UTRAN or the HeNB in E-UTRAN are base stations for, for example, home, corporate, and commercial access services. Non-Patent Document 4 discloses three different modes of access to HeNB and HNB. Specifically, they are the Open access mode, the Closed access mode, and the Hybrid access mode.

[0055] Each mode has the following characteristics. In the open access mode, HeNBs and HNBs operate as normal cells of a normal operator. In the closed access mode, HeNBs and HNBs operate as CSG cells. This is a CSG cell that can only be accessed by CSG members. In the hybrid access mode, it is a CSG cell where non-CSG members are also permitted to access simultaneously. A cell in the hybrid access mode (also referred to as a hybrid cell) is, in other words, a cell that supports both the open access mode and the closed access mode.

[0056] In 3GPP, among all PCIs (Physical Cell Identities), there is a PCI range reserved by the network for use by CSG cells (see Section 10.5.1.1 of Non-Patent Document 1). Splitting the PCI range is sometimes referred to as PCI split. PCI split information is notified from a base station to mobile terminals under its umbrella in system information. Non-Patent Document 5 discloses the basic operation of a mobile terminal using PCI split. A mobile terminal without PCI split information needs to perform cell search using all PCIs (for example, using all 504 codes). In contrast, a mobile terminal with PCI split information can perform cell search using the PCI split information.

[0057] Also in 3GPP, as Release 10, the standardization of Long Term Evolution Advanced (LTE-A) is underway (see Non-Patent Document 6 and Non-Patent Document 7).

[0058] In the LTE-A system, in order to achieve high communication speeds, high throughput at the cell edge, and new coverage areas, etc., supporting relays (Relay: Relay Node (RN)) is being considered. The relay node is wirelessly connected to the radio access network via a donor cell (Donor cell; Donor eNB; DeNB). Within the range of the donor cell, the link from the network (Network: NW) to the relay node shares the same frequency band (hereinafter sometimes referred to as the "frequency band") as the link from the network to the UE. In this case, it is also possible for a Release 8 UE to connect to the said donor cell. The link between the donor cell and the relay node is called the backhaul link, and the link between the relay node and the UE is called the access link.

[0059] As a multiplexing method for the backhaul link in FDD (Frequency Division Duplex), the transmission from the DeNB to the RN is carried out in the downlink (DL) frequency band, and the transmission from the RN to the DeNB is carried out in the uplink (UL) frequency band. As a resource division method in the relay, the link from the DeNB to the RN and the link from the RN to the UE are time-division multiplexed in one frequency band, and the link from the RN to the DeNB and the link from the UE to the RN are also time-division multiplexed in one frequency band. By doing so, in the relay, it is possible to prevent the transmission of the relay from interfering with the reception of the self-relay.

[0060] In 3GPP, not only normal eNBs (macro cells) but also so-called local nodes such as pico eNBs (pico cells), HeNB / HNB / CSG cells, nodes for hot zone cells, relay nodes, and Remote Radio Heads (RRH) are being considered.

[0061] These local nodes are arranged to complement macro cells in response to the requirements of various services such as high-speed and high-capacity communication. For example, a large number of HeNBs are required to be installed in shopping streets, apartment buildings, schools, companies, etc. For this reason, there are cases where HeNBs are installed within the coverage of macro cells. When a HeNB is installed within the coverage of a macro cell, interference will occur among the macro cell, the HeNB, and the mobile terminal (UE). Due to these interferences, the communication of the mobile terminal (UE) with the macro cell or the HeNB is hindered, resulting in a decrease in communication speed. Furthermore, when the interference power increases, communication will become impossible. Therefore, a method is required to avoid the interference that occurs in the situation where these macro cells and local nodes are mixedly arranged and to optimize the communication quality.

[0062] In 3GPP, the study of Machine Type Communication (MTC) technology is in progress (see Non-Patent Document 8). The number of MTC devices (MTCDs) is expected to be extremely large. In MTC services, situations occur where data is communicated simultaneously from a large number of MTCDs or to a large number of MTCDs. This causes a problem of congestion in the Core Network.

[0063] In order to solve such problems, Non-Patent Document 9 discloses that an eNB holds back and aggregates signaling messages common to MTCDs in the same MTCD group to make the signaling messages compact.

Prior Art Documents

Non-Patent Documents

[0064]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 4

Non-Patent Document 5

Non-Patent Document 6

Non-Patent Document 7

Non-Patent Document 8

Non-Patent Document 9

Summary of the Invention

Problems to be Solved by the Invention

[0065] As described above, it is expected that the number of MTCDs will be extremely large. Also, it is expected that the number of mobile terminals that a HeNB can accommodate is significantly less compared to the number of mobile terminals that a macro cell can accommodate. Therefore, when many MTCDs access a HeNB at once, the number of mobile terminals accommodated by the HeNB may reach the number of mobile terminals that the HeNB can accommodate, and the HeNB may be occupied by the MTCDs, resulting in the inability to accommodate mobile terminals that are not MTCDs.

[0066] An object of the present invention is to provide a communication system, a base station device, and a communication terminal device that can prevent the base station device from being occupied by a specific communication terminal device and prevent the inability to accommodate other communication terminal devices.

Means for Solving the Problems

[0067] The communication system of the present invention is a communication system including a base station device and a plurality of communication terminal devices capable of wireless communication with the base station device. The base station device notifies, as system information, operation restriction information regarding the restricted operations of restricted terminal devices, which are some of the plurality of communication terminal devices whose operations are restricted, to the communication terminal devices existing within the communicable range. The communication terminal device notified of the operation restriction information determines whether it is a restricted terminal device based on the information stored in the SIM (Subscriber Identity Module). If it determines that it is a restricted terminal device, it operates according to the operation restriction information. Information for changing the operation restriction information is notified using a paging message, and the operation restriction information is information for restricting the transmission of an RRC (Radio Resource Control) connection request signal from the restricted terminal device to the base station device. The base station device of the present invention is a base station device capable of wireless communication with a plurality of communication terminal devices. The base station device notifies, as system information, operation restriction information regarding the restricted operations of restricted terminal devices, which are some of the plurality of communication terminal devices whose operations are restricted, to the communication terminal devices existing within the communicable range. Information for changing the operation restriction information is notified using a paging message, and the operation restriction information is information for restricting the transmission of an RRC (Radio Resource Control) connection request signal from the restricted terminal device to the base station device.

[0068] The communication terminal device of the present invention is a communication terminal device capable of wireless communication with a base station device. It determines whether the device itself is a restricted terminal device based on the information stored in the SIM (Subscriber Identity Module). When it is determined that the device is a restricted terminal device, it operates based on the operation restriction information notified as system information by the base station device. Information for changing the operation restriction information is notified using a paging message, and the operation restriction information is information for restricting the transmission of an RRC (Radio Resource Control) connection request signal from the restricted terminal device to the base station device.

Effect of the Invention

[0069] According to the communication system of the present invention, the base station device can restrict the operation of the restricted terminal device in a form that distinguishes it from communication terminal devices other than the restricted terminal device. This can prevent the base station device from being occupied by the restricted terminal device and prevent the inability to accommodate communication terminal devices other than the restricted terminal device. Therefore, the provision of services to communication terminal devices other than the restricted terminal device by the base station device can be maintained.

[0070] Also, according to the base station device of the present invention, the operation of the restricted terminal device can be restricted in a form that distinguishes it from communication terminal devices other than the restricted terminal device. This can prevent the base station device from being occupied by the restricted terminal device and prevent the inability to accommodate communication terminal devices other than the restricted terminal device. Therefore, the provision of services to communication terminal devices other than the restricted terminal device by the base station device can be maintained. Also, according to the communication terminal device of the present invention, the operation can be restricted based on the operation restriction information. This can prevent the base station device from being occupied by the restricted terminal device, which is a part of the communication terminal devices whose operations are restricted among a plurality of communication terminal devices, and prevent the inability to accommodate communication terminal devices other than the restricted terminal device. Therefore, the provision of services to communication terminal devices other than the restricted terminal device by the base station device can be maintained.

[0071] The objectives, features, aspects, and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0073] Embodiment 1. FIG. 7 is a block diagram showing the overall configuration of a mobile communication system of the LTE system currently under discussion in 3GPP. Currently in 3GPP, the overall configuration of a system including a CSG (Closed Subscriber Group) cell (Home-eNodeB (Home-eNB; HeNB) of E-UTRAN, Home-NB (HNB) of UTRAN) and a non-CSG cell (eNodeB (eNB) of E-UTRAN, NodeB (NB) of UTRAN, BSS of GERAN) is being studied, and for E-UTRAN, a configuration as shown in FIG. 7 has been proposed (see Section 4.6.1 of Non-Patent Document 1).

[0074] Explanation will be given with reference to FIG. 7. A mobile terminal device (hereinafter referred to as "mobile terminal" or "UE") 71 can communicate wirelessly with a base station device (hereinafter referred to as "base station") 72 and performs signal transmission and reception through wireless communication. The mobile terminal device corresponds to a communication terminal device. Hereinafter, the mobile terminal device may be referred to as a "communication terminal" in some cases. The base station 72 is classified into an eNB 72-1 which is a macro cell and a Home-eNB 72-2 which is a local node. The eNB 72-1 corresponds to a large-scale base station device and has a relatively large large-scale coverage as a coverage within which it can communicate with the mobile terminal UE 71. The Home-eNB 72-2 corresponds to a small-scale base station device and has a relatively small small-scale coverage as a coverage.

[0075] The eNB 72-1 is connected to an MME, or an S-GW, or an MME / S-GW unit (hereinafter sometimes referred to as the "MME unit") 73 including an MME and an S-GW, via an S1 interface, and control information is communicated between the eNB 72-1 and the MME unit 73. A plurality of MME units 73 may be connected to one eNB 72-1. The eNBs 72-1 are connected to each other via an X2 interface, and control information is communicated between the eNBs 72-1.

[0076] The Home-eNB 72-2 is connected to the MME unit 73 via an S1 interface, and control information is communicated between the Home-eNB 72-2 and the MME unit 73. A plurality of Home-eNBs 72-2 may be connected to one MME unit 73. Alternatively, the Home-eNB 72-2 is connected to the MME unit 73 via a HeNBGW (Home-eNB GateWay) 74. The Home-eNB 72-2 and the HeNBGW 74 are connected via an S1 interface, and the HeNBGW 74 and the MME unit 73 are connected via an S1 interface. One or more Home-eNBs 72-2 are connected to one HeNBGW 74, and information is communicated through the S1 interface. The HeNBGW 74 is connected to one or more MME units 73, and information is communicated through the S1 interface.

[0077] Furthermore, currently in 3GPP, the following configurations are being considered. The X2 interface between the Home-eNBs 72-2 is not supported. From the MME unit 73, the HeNBGW 74 appears as an eNB 72-1. From the Home-eNB 72-2, the HeNBGW 74 appears as an MME unit 73. Regardless of whether the Home-eNB 72-2 is connected to the MME unit 73 via the HeNBGW 74, the interface between the Home-eNB 72-2 and the MME unit 73 is the same as the S1 interface. The HeNBGW 74 does not support mobility to or from the Home-eNB 72-2 that spans multiple MME units 73. The Home-eNB 72-2 supports only one cell.

[0078] FIG. 8 is a block diagram showing the configuration of the mobile terminal (mobile terminal 71 in FIG. 7) according to the present invention. The transmission process of the mobile terminal 71 shown in FIG. 8 will be described. First, the control data from the protocol processing unit 801 and the user data from the application unit 802 are stored in the transmission data buffer unit 803. The data stored in the transmission data buffer unit 803 is passed to the encoder unit 804, and encoding processes such as error correction are performed. There may be data that is directly output from the transmission data buffer unit 803 to the modulation unit 805 without undergoing the encoding process. The data encoded by the encoder unit 804 is subjected to modulation processing by the modulation unit 805. The modulated data is converted into a baseband signal and then output to the frequency conversion unit 806, where it is converted to a radio transmission frequency. Thereafter, a transmission signal is transmitted from the antenna 807 to the base station 72.

[0079] Also, the reception process of the mobile terminal 71 is executed as follows. A radio signal from the base station 72 is received by the antenna 807. The received signal is converted from the radio reception frequency to a baseband signal by the frequency conversion unit 806, and demodulation processing is performed by the demodulation unit 808. The demodulated data is passed to the decoder unit 809, and decoding processes such as error correction are performed. Among the decoded data, the control data is passed to the protocol processing unit 801, and the user data is passed to the application unit 802. A series of processes of the mobile terminal 71 are controlled by the control unit 810. Therefore, although omitted in FIG. 8, the control unit 810 is connected to each of the units 801 to 809.

[0080] FIG. 9 is a block diagram showing the configuration of a base station (base station 72 in FIG. 7) according to the present invention. The transmission process of the base station 72 shown in FIG. 9 will be described. The EPC communication unit 901 transmits and receives data between the base station 72 and the EPC (MME unit 73, HeNB GW 74, etc.). The other base station communication unit 902 transmits and receives data with other base stations. Since the X2 interface between the Home-eNBs 72-2 is not supported, it is conceivable that the other base station communication unit 902 does not exist in the Home-eNB 72-2. The EPC communication unit 901 and the other base station communication unit 902 each exchange information with the protocol processing unit 903. The control data from the protocol processing unit 903, as well as the user data and control data from the EPC communication unit 901 and the other base station communication unit 902, are stored in the transmission data buffer unit 904.

[0081] The data stored in the transmission data buffer unit 904 is passed to the encoder unit 905, and encoding processing such as error correction is performed. There may be data that is directly output from the transmission data buffer unit 904 to the modulation unit 906 without undergoing the encoding process. The encoded data is subjected to modulation processing in the modulation unit 906. The modulated data is converted into a baseband signal and then output to the frequency conversion unit 907, where it is converted into a radio transmission frequency. Thereafter, a transmission signal is transmitted from the antenna 908 to one or more mobile terminals 71.

[0082] Also, the reception processing of the base station 72 is executed as follows. A radio signal from one or more mobile terminals 71 is received by the antenna 908. The received signal is converted from the radio reception frequency to a baseband signal by the frequency conversion unit 907, and demodulation processing is performed by the demodulation unit 909. The demodulated data is passed to the decoder unit 910, and decoding processing such as error correction is performed. Among the decoded data, the control data is passed to the protocol processing unit 903 or the EPC communication unit 901 and the other base station communication unit 902, and the user data is passed to the EPC communication unit 901 and the other base station communication unit 902. A series of processes of the base station 72 are controlled by the control unit 911. Therefore, although omitted in FIG. 9, the control unit 911 is connected to each unit 901 to 910.

[0083] The functions of Home-eNB72-2 currently being discussed in 3GPP are shown below (see Section 4.6.2 of Non-Patent Document 1). Home-eNB72-2 has the same functions as eNB72-1. In addition, when connecting to the HeNBGW74, Home-eNB72-2 has the function of discovering an appropriate serving HeNBGW74. Home-eNB72-2 is uniquely connected to one HeNBGW74. That is, in the case of connection to the HeNBGW74, Home-eNB72-2 does not use the Flex function in the S1 interface. When Home-eNB72-2 is connected to one HeNBGW74, it does not connect to another HeNBGW74 or another MME unit 73 at the same time.

[0084] The TAC and PLMN ID of Home-eNB72-2 are supported by the HeNBGW74. When Home-eNB72-2 is connected to the HeNBGW74, the selection of the MME unit 73 in "UE attachment" is performed by the HeNBGW74 instead of Home-eNB72-2. Home-eNB72-2 may be deployed without a network plan. In this case, Home-eNB72-2 is moved from one geographical area to another geographical area. Therefore, in this case, Home-eNB72-2 needs to be connected to different HeNBGW74 depending on the location.

[0085] FIG. 10 is a block diagram showing the configuration of the MME according to the present invention. In FIG. 10, the configuration of the MME 73a included in the MME unit 73 shown in FIG. 7 described above is shown. The PDN GW communication unit 1001 transmits and receives data between the MME 73a and the PDN GW. The base station communication unit 1002 transmits and receives data via the S1 interface between the MME 73a and the base station 72. When the data received from the PDN GW is user data, the user data is passed from the PDN GW communication unit 1001 to the base station communication unit 1002 via the user plain communication unit 1003 and transmitted to one or more base stations 72. When the data received from the base station 72 is user data, the user data is passed from the base station communication unit 1002 to the PDN GW communication unit 1001 via the user plain communication unit 1003 and transmitted to the PDN GW.

[0086] When the data received from the PDN GW is control data, the control data is passed from the PDN GW communication unit 1001 to the control plain control unit 1005. When the data received from the base station 72 is control data, the control data is passed from the base station communication unit 1002 to the control plain control unit 1005.

[0087] The HeNBGW communication unit 1004 is provided when the HeNBGW 74 exists, and transmits and receives data via the interface (IF) between the MME 73a and the HeNBGW 74 according to the information type. The control data received from the HeNBGW communication unit 1004 is passed from the HeNBGW communication unit 1004 to the control plain control unit 1005. The result of the processing in the control plain control unit 1005 is transmitted to the PDN GW via the PDN GW communication unit 1001. Also, the result processed by the control plain control unit 1005 is transmitted to one or more base stations 72 via the S1 interface via the base station communication unit 1002, and is also transmitted to one or more HeNBGWs 74 via the HeNBGW communication unit 1004.

[0088] The control plane control unit 1005 includes an NAS security unit 1005-1, an SAE bearer control unit 1005-2, an idle state mobility management unit 1005-3, etc., and performs overall processing for the control plane. The NAS security unit 1005-1 performs security of NAS (Non-Access Stratum) messages, etc. The SAE bearer control unit 1005-2 performs management of SAE (System Architecture Evolution) bearers, etc. The idle state mobility management unit 1005-3 performs mobility management in the standby state (LTE-IDLE state, also simply referred to as idle), generation and control of paging signals in the standby state, addition, deletion, update, search of the tracking area (TA) of one or more mobile terminals 71 under its umbrella, tracking area list (TA List) management, etc.

[0089] The MME 73a initiates the paging protocol by transmitting a paging message to a cell belonging to the tracking area (Tracking Area: TA) in which the UE is registered. The management of the CSG of the Home-eNB 72-2 connected to the MME 73a, the management of the CSG-ID, and the white list management may be performed by the idle state mobility management unit 1005-3.

[0090] In the management of CSG - IDs, the relationship between the mobile terminals corresponding to the CSG - IDs and the CSG cells is managed (added, deleted, updated, searched). For example, it may be the relationship between one or more mobile terminals registered for user access with a certain CSG - ID and the CSG cell belonging to the CSG - ID. In the white list management, the relationship between the mobile terminal and the CSG - ID is managed (added, deleted, updated, searched). For example, the white list may store one or more CSG - IDs registered by a certain mobile terminal. These CSG - related management may be performed in other parts of the MME73a. A series of processes of the MME73a are controlled by the control unit 1006. Therefore, although omitted in FIG. 10, the control unit 1006 is connected to each of the units 1001 - 1005.

[0091] The functions of the MME73a currently being discussed in 3GPP are shown below (see Section 4.6.2 of Non - Patent Document 1). The MME73a performs access control for one or a plurality of mobile terminals that are members of a CSG (Closed Subscriber Groups). The MME73a optionally allows the execution of paging optimization.

[0092] FIG. 11 is a block diagram showing the configuration of the HeNBGW74 shown in FIG. 7, which is the HeNBGW according to the present invention. The EPC communication unit 1101 transmits and receives data via the S1 interface between the HeNBGW74 and the MME73a. The base station communication unit 1102 transmits and receives data via the S1 interface between the HeNBGW74 and the Home - eNB72 - 2. The location processing unit 1103 performs a process of transmitting registration information and the like among the data from the MME73a passed via the EPC communication unit 1101 to a plurality of Home - eNB72 - 2. The data processed by the location processing unit 1103 is passed to the base station communication unit 1102 and transmitted to one or a plurality of Home - eNB72 - 2 via the S1 interface.

[0093] Data that only needs to pass (transmit) without requiring the processing in the location processing unit 1103 is passed from the EPC communication unit 1101 to the base station communication unit 1102 and transmitted to one or more Home-eNBs 72-2 via the S1 interface. A series of processes of the HeNBGW 74 are controlled by the control unit 1104. Therefore, although omitted in FIG. 11, the control unit 1104 is connected to each of the units 1101 to 1103.

[0094] The functions of the HeNBGW 74 currently being discussed in 3GPP are shown below (see Section 4.6.2 of Non-Patent Document 1). The HeNBGW 74 relays for the S1 application. Although it is a part of the procedure of the MME 73a to the Home-eNB 72-2, the HeNBGW 74 terminates the S1 application not related to the mobile terminal 71. When the HeNBGW 74 is arranged, procedures not related to the mobile terminal 71 are communicated between the Home-eNB 72-2 and the HeNBGW 74 and between the HeNBGW 74 and the MME 73a. The X2 interface is not set between the HeNBGW 74 and other nodes. The HeNBGW 74 optionally admits to execute paging optimization.

[0095] Next, an example of a general cell search method in a mobile communication system is shown. FIG. 12 is a flowchart showing an outline from the cell search to the standby operation performed by a mobile terminal (UE) in an LTE-based communication system. When starting the cell search, the mobile terminal synchronizes the slot timing and the frame timing using the first synchronization signal (P-SS) and the second synchronization signal (S-SS) transmitted from surrounding base stations in step ST1201. Combining the P-SS and the S-SS, the synchronization signal (SS) is assigned a synchronization code that corresponds one-to-one to the PCI (Physical Cell Identity) assigned to each cell. The number of PCIs is currently being considered to be 504. Synchronization is taken using these 504 PCIs, and the PCI of the cell for which synchronization has been achieved is detected (specified).

[0096] Next, for the cell that has been synchronized, in step ST1202, the cell-specific Reference Signal (CRS) transmitted from the base station for each cell is detected, and the received power (also referred to as RSRP) is measured. The reference signal RS uses a code that corresponds one-to-one with the PCI, and by correlating with that code, it can be separated from other cells. By deriving the code for the RS of the cell from the PCI identified in step ST1201, it becomes possible to detect the RS and measure the RS received power.

[0097] Next, in step ST1203, from among one or more cells detected up to step ST1202, the cell with the best reception quality of the RS (for example, the cell with the highest received power of the RS, that is, the best cell) is selected.

[0098] Next, in step ST1204, the PBCH of the best cell is received to obtain the BCCH, which is the broadcast information. The BCCH on the PBCH contains the Master Information Block (MIB). Therefore, by receiving the PBCH and obtaining the BCCH, the MIB can be obtained. Examples of the information in the MIB include the DL (downlink) system bandwidth (also called the transmission bandwidth configuration: dl-bandwidth), the number of transmission antennas, the SFN (System Frame Number), etc.

[0099] Next, in step ST1205, based on the cell configuration information in the MIB, the DL-SCH of the cell is received to obtain the System Information Block (SIB) 1 in the broadcast information BCCH. SIB1 contains information related to access to the cell, information related to cell selection, and scheduling information for other SIBs (SIBk; k is an integer greater than or equal to 2). Also, SIB1 contains the TAC (Tracking Area Code).

[0100] Next, in step ST1206, the mobile terminal compares the TAC of SIB1 received in step ST1205 with the TACs in the TA (Tracking Area) list already held by the mobile terminal. As a result of the comparison, if the TAC received in step ST1205 is the same as the TAC included in the TA list, the mobile terminal enters the standby operation in the cell. If, after comparison, the TAC received in step ST1205 is not included in the TA list, the mobile terminal requests a TA change to perform a TAU (Tracking Area Update) to the core network (Core Network, EPC) (including MME, etc.) through the cell. The core network updates the TA list based on the identification number (UE-ID, etc.) of the mobile terminal sent from the mobile terminal together with the TAU request signal. The core network transmits the updated TA list to the mobile terminal. The mobile terminal rewrites (updates) the TAC list held by the mobile terminal with the received TA list. Thereafter, the mobile terminal enters the standby operation in the cell.

[0101] In LTE, LTE-A, and UMTS (Universal Mobile Telecommunication System), the introduction of CSG (Closed Subscriber Group) cells is being considered. As described above, access is permitted only to one or more mobile terminals registered in the CSG cell. One or more mobile terminals registered with the CSG cell constitute one CSG. The CSG configured in this way is assigned a unique identification number called a CSG-ID. Note that one CSG may include a plurality of CSG cells. If a mobile terminal registers in any one CSG cell, it can access other CSG cells belonging to the CSG to which the CSG cell belongs.

[0102] In addition, Home eNBs in LTE and LTE-A and Home NB in UMTS may be used as CSG cells. Mobile terminals registered in a CSG cell have a whitelist. Specifically, the whitelist is stored in a SIM (Subscriber Identity Module) / USIM. The whitelist stores the CSG information of the CSG cells in which the mobile terminal is registered. Specifically, as CSG information, a CSG-ID, TAI (Tracking Area Identity), TAC, etc. can be considered. If the CSG-ID and the TAC are associated with each other, either one of them is sufficient. Also, if the CSG-ID and the TAC and the GCI (Global Cell Identity) are associated with each other, the GCI may also be used.

[0103] From the above, a mobile terminal that does not have a whitelist (including the case where the whitelist is empty in the present invention) cannot access a CSG cell and can only access non-CSG cells. On the other hand, a mobile terminal that has a whitelist can access both the CSG cell with the registered CSG-ID and non-CSG cells.

[0104] In 3GPP, among all PCIs (Physical Cell Identities), there is a PCI range reserved by the network for use by CSG cells (see Non-Patent Document 1). Splitting the PCI range is sometimes referred to as PCI split. PCI split information is notified from a base station to mobile terminals under its umbrella in system information. Non-Patent Document 5 discloses the basic operation of a mobile terminal using PCI split. A mobile terminal that does not have PCI split information needs to perform cell search using all PCIs (for example, using all 504 codes). In contrast, a mobile terminal that has PCI split information can perform cell search using the PCI split information.

[0105] Also in 3GPP, it has been determined that the PCI for a hybrid cell is not included in the PCI range for a CSG cell (see Section 10.7 of Non-Patent Document 1).

[0106] In 3GPP, there are two modes regarding how a mobile terminal selects or reselects a CSG cell. The first is the Automatic mode. The features of the Automatic mode are as follows. Using the Allowed CSG ID List in the mobile terminal, selection or reselection is performed. After the selection of the PLMN is completed, it camps on one cell in the selected PLMN only when it is a non-CSG cell or a CSG cell with a CSG ID existing in the Allowed CSG List. If the Allowed CSG List of the mobile terminal is empty, the mobile terminal stops the autonomous search function for CSG cells (see Section 5.2.4.8.1 of Non-Patent Document 3).

[0107] The second is the Manual mode. The features of the Manual mode are as follows. The mobile terminal shows the user the list of CSGs available in the currently selected PLMN. The list of CSGs provided by the mobile terminal to the user is not limited to the CSGs included in the Allowed CSG List stored in the mobile terminal. After the user selects a CSG based on the list of CSGs, the mobile terminal camps on the cell with the selected CSG ID and attempts to register (see Non-Patent Document 3).

[0108] For HeNBs and HNBs, support for various services is required. For example, the operator registers the mobile terminal to certain determined HeNBs and HNBs and allows only the registered mobile terminals to access the cells of the HeNBs and HNBs, thereby increasing the radio resources available to the mobile terminal and enabling high-speed communication. Accordingly, the operator provides services such as setting a higher charging fee than normal.

[0109] To realize such services, a Closed Subscriber Group (CSG) cell that can only be accessed by registered (subscribed, member) mobile terminals is introduced. CSG cells (Closed Subscriber Group cells) are required to be installed in large numbers in shopping streets, condominiums, schools, companies, etc. For example, in a shopping street, a CSG cell is installed for each store, in a condominium for each room, in a school for each classroom, and in a company for each section, and only users registered in each CSG cell can use the CSG cell. HeNB / HNB is required not only to complement communication outside the coverage of macro cells (area-complementary HeNB / HNB), but also to support various services as described above (service-providing HeNB / HNB). Therefore, there are cases where HeNB / HNB is installed within the coverage of macro cells.

[0110] In 3GPP, the study of MTC technology is underway (see Non-Patent Document 8). Different from conventional Human to Human (H2H) communication, MTC is Machine to Machine (M2M) communication. That is, it does not require Human Interaction, that is, interaction between people. Application examples of services using MTC technology (hereinafter referred to as "MTC services") include metering of gas, electricity, water, etc., that is, measurement, as well as transportation management and order management (Tracking & Tracing). As a characteristic of MTC services, the number of MTC devices (MTCD) for MTC may be extremely large. As an example, it is assumed that there are more than 30,000 MTCDs under the umbrella of one cell.

[0111] In 3GPP, the architecture of MTC is being studied (see 3GPP R3-100315 (hereinafter referred to as "Non-Patent Document 10")). FIG. 13 is a diagram showing an example of the architecture of MTC being studied in 3GPP. Support for MTC services is being studied not only in LTE and LTE-A communication systems but also in WCDMA communication systems.

[0112] In FIG. 13, MTCDs 1301 to 1304 and NB / eNB 1305 are connected by Uu interfaces 1311 to 1314. SGSN / MME (Serving GPRS Support Node / Mobility Management Entity) 1306 is connected to NB / eNB 1305 by IuPS / S1 interface 1315. Although not shown, there is a Radio Network Controller (RNC) between the NB and the SGSN. The NB and the RNC are connected by an Iub interface, and the RNC is connected to the SGSN via an IuPS interface.

[0113] HLR / HSS (Home Location Register / Home Subscriber Server) 1307 is connected to SGSN / MME 1306 via Gr / S6a interface 1316. The communication operator area 1317 includes NB / eNB 1305, SGSN / MME 1306, HLR / HSS 1307, etc.

[0114] The MTC server 1308 is included in the communication operator area 1317. The MTC user 1309 that provides MTC services is connected to the MTC server 1308 via an Application Program Interface (API) 1310. Regarding which node in the communication operator area 1317 the MTC server 1308 is connected to, it is currently under study in 3GPP.

[0115] Information for the MTC service is notified from the MTC server 1308 to the MTCDs 1301 to 1304 by the MTC user 1309 using the NB / eNB 1305, SGSN / MME 1306, and HLR / HSS 1307, which are nodes in the communication operator area 1317. Conversely, information from the MTCDs 1301 to 1304 is notified to the MTC server 1308 using the NB / eNB 1305, SGSN / MME 1306, and HLR / HSS 1307, which are nodes in the communication operator area 1317, and this information is used by the MTC user 1309.

[0116] The problems to be solved in Embodiment 1 will be described below. The number of MTCDs is expected to be huge. Also, the number of mobile terminals that a HeNB can accommodate is expected to be much smaller compared to the number of mobile terminals that a macro cell can accommodate. Therefore, if many MTCDs access the HeNB at once, the HeNB may be occupied by the MTCDs, and there is a risk that the HeNB will not be able to accommodate mobile terminals that are not MTCDs (hereinafter sometimes referred to as "normal UEs").

[0117] A specific example will be shown below. Assume that a HeNB is installed in a house. Also assume that the HeNB is operating in a hybrid access mode. Therefore, even passing-by mobile terminals that are not registered with the same CSG-ID as the HeNB can access the HeNB.

[0118] For example, assume that a truck loaded with a large number of packages is parked in front of a house. Assume that an MTCD is attached to each package for tracking. For many MTCDs, the base station with the best reception quality is the HeNB installed in the house. Therefore, a large number of MTCDs attached to the packages loaded on the truck will reselect the HeNB installed in the house as the serving cell.

[0119] When an access occurs from an MTCD to the MTC server to report the current location, accesses occur simultaneously from a large number of MTCDs to the HeNB inside the house. As a result, the number of mobile terminals accommodated by the HeNB (hereinafter sometimes referred to as the "accommodation number") reaches the number of mobile terminals that can be accommodated by the HeNB (hereinafter sometimes referred to as the "accommodable number"). In this case, even if a new access occurs from a normal UE, the HeNB cannot accommodate the normal UE and cannot provide services to the normal UE.

[0120] As a method of restricting access from mobile terminals such as MTCDs to the HeNB, there is CSG (Closed Subscriber Group cell) in existing technologies. However, when the HeNB is operating in the open access mode or the hybrid access mode, mobile terminals not registered with the same CSG-ID as the HeNB can also access the HeNB. Therefore, simply restricting access to the HeNB by the existing CSG cannot solve the above-mentioned problems.

[0121] The solution in Embodiment 1 is shown below. The base station notifies the mobile terminals existing within the communicable range, that is, the mobile terminals under its umbrella, of the MTCD restriction information in the base station itself. The mobile terminals that receive the MTCD restriction information include MTCDs and normal UEs. The MTCD corresponds to the restricted terminal device, and the normal UE corresponds to the communication terminal device other than the restricted terminal device. The MTCD restriction information indicates the operation in which the MTCD is restricted.

[0122] The MTCD that has received the MTCD restriction information operates according to the restriction indicated by the MTCD restriction information. The normal UE that has received the MTCD restriction information does not operate according to the restriction indicated by the MTCD restriction information. The normal UE that has received the MTCD restriction information may operate as normal.

[0123] As a result, the base station can operate while distinguishing between a normal UE and an MTCD and restricting the operation. Therefore, in the HeNB which is a base station, if the operation of the MTCD is restricted by distinguishing between the normal UE and the MTCD using the MTCD restriction information, the problem that the number of mobile terminals accommodated by the HeNB reaches the accommodable number due to the access of the MTCD, the HeNB is occupied by the MTCD, and the normal UE cannot be accommodated can be solved.

[0124] As specific examples of the restrictions indicated by the MTCD restriction information, seven of the following (1) to (7) are disclosed.

[0125] (1) Whether the MTCD can access or not. As specific examples of access, five of the following (a1) to (a5) are disclosed. (a1) Uplink control data transmission. (a2) Uplink traffic data transmission. It may be the transmission of user data. (a3) RACH transmission. (a4) Transmission of an RRC connection request (RRC Connection Request). (a5) A combination of (a1) to (a4) above.

[0126] (2) Whether the MTCD can camp on to obtain a normal service. In other words, whether the MTCD can be selected as a suitable cell.

[0127] (3) Whether the MTCD can camp on to obtain a limited service. In other words, whether the MTCD can be selected as an acceptable cell. As specific examples of the limited service, four of the following (b1) to (b4) are disclosed. (b1) Emergency call transmission. (b2) Reception of ETWS. (b3) Reception of CMAS. (b4) A combination of (b1) to (b3) above.

[0128] (4) Whether the MTCD is prohibited from being a candidate for cell selection and reselection. In other words, whether the cell is a barred cell for the MTCD.

[0129] (5) Whether the MTCD is prohibited from roaming.

[0130] (6) Whether the MTCD is prohibited from handing over.

[0131] (7) The combinations of the above (1) to (6).

[0132] By notifying one restriction with the MTCD restriction information, it may be regarded as also notifying other restrictions. The combination may be determined statically. As specific examples of the combination, 11 of the following (A1) to (A11) are disclosed.

[0133] (A1) When the MTCD restriction information indicates that it is inaccessible, it means that the MTCD is inaccessible but can camp on to obtain normal services.

[0134] (A2) When the MTCD restriction information indicates that it is inaccessible, it means that the MTCD is inaccessible but can camp on to obtain limited services.

[0135] (A3) When the MTCD restriction information indicates that it is inaccessible, it means that the MTCD is inaccessible but is not prohibited from being a candidate for cell selection and reselection.

[0136] (A4) When the MTCD restriction information indicates that it is inaccessible, it means that the MTCD is inaccessible but is not prohibited from roaming.

[0137] (A5) When the MTCD restriction information indicates that it is inaccessible, it means that the MTCD is inaccessible but is not prohibited from handing over.

[0138] If the MTCD restriction information indicates that camping on is not possible to obtain normal services, it means that the MTCD is not able to camp on to obtain normal services, but is able to camp on to obtain limited services.

[0139] (A7) If the MTCD restriction information indicates that camping on is not possible to obtain normal services, it means that the MTCD is not able to camp on to obtain normal services, but is not prohibited from being a candidate for cell selection and reselection.

[0140] (A8) If the MTCD restriction information indicates that camping on is not possible to obtain normal services, it means that the MTCD is not able to camp to obtain normal services, but is not prohibited from roaming in.

[0141] (A9) If the MTCD restriction information indicates that camping on is not possible to obtain normal services, it means that the MTCD is not able to camp to obtain normal services, but is not prohibited from handing over.

[0142] (A10) If the MTCD restriction information indicates that camping on is not possible to obtain limited services, it means that the MTCD is not able to camp on to obtain limited services, but is not prohibited from roaming in.

[0143] (A11) If the MTCD restriction information indicates that camping on is not possible to obtain limited services, it means that the MTCD is not able to camp on to obtain limited services, but is not prohibited from handing over.

[0144] When "impossible" is indicated by the MTCD restriction information, restrictions that are more stringent than the operations indicated by the MTCD restriction information may be regarded as not applying. Among the specific examples of the restrictions indicated by the MTCD restriction information, the restriction in Specific Example (1) is the loosest restriction, and it is assumed that the greater the number of the specific example, that is, as going from (1) to (4), the more stringent the restriction. For convenience, the explanation will be given excluding Specific Examples (5), (6), and (7).

[0145] For example, in Specific Example (1), when the MTCD indicates that access is impossible, it is regarded that no restrictions more stringent than this restriction apply. Therefore, according to this restriction information, it is considered that the MTCD can camp on to obtain normal services, the MTCD can camp on to obtain limited services, and the MTCD can be a candidate for cell selection and reselection.

[0146] The MTCD restriction information does not have to be a binary value indicating two cases such as possible or not as the restriction content. As specific examples of non-binary restriction information, the following two cases (1) and (2) are disclosed.

[0147] (1) Notify multi-values as restriction information. As specific restriction information, the case of using 2 bits is shown below. "11" indicates no restriction. "10" indicates that the MTCD cannot camp on to obtain normal services. "01" indicates that the MTCD cannot camp on to obtain limited services. "00" indicates that the MTCD is prohibited from being a candidate for cell selection and reselection. By using multi-values as restriction information, a more flexible communication system can be constructed compared with the case of using binary values.

[0148] (2) It indicates a restriction depending on whether to notify restriction information. As specific examples, the following two cases (a1) and (a2) are shown. (a1) "There is MTCD restriction information", that is, "notify MTCD restriction information", indicates that it is impossible for the MTCD to camp on to obtain normal services. "There is no MTCD restriction information", that is, "do not notify MTCD restriction information", indicates that it is possible for the MTCD to camp on to obtain normal services. (a2) "There is MTCD restriction information", that is, "notify MTCD restriction information", indicates that it is impossible for the MTCD to camp on to obtain normal services. "There is no MTCD restriction information", that is, "do not notify MTCD restriction information", indicates no restriction. When using restriction information that indicates a restriction depending on whether to notify as in (a1) or (a2), different from the case of using two values as restriction information, in a base station that does not restrict the MTCD, there is no need to notify MTCD restriction information. Therefore, there is no need to modify the existing base station. Thus, a communication system with excellent backward compatibility can be constructed.

[0149] The MTCD restriction information does not necessarily have to be restriction information for "MTCD". As specific examples, the following three cases (1) to (3) are disclosed.

[0150] (1) Restriction information according to the priority of the MTCD. It is effective when distinguishing between an MTCD with a high priority and an MTCD with a low priority in a communication system. As specific examples of combinations with the restriction information, the following three cases (a1) to (a3) are disclosed. (a1) The MTCD restriction information indicates restriction information for an MTCD with a low priority. (a2) Provide separately the MTCD restriction information for an MTCD with a high priority and the MTCD restriction information for an MTCD with a low priority. (a3) The MTCD restriction information indicates restriction information for all MTCDs. Also, the priority does not have to be binary.

[0151] (2) Restriction information according to the MTCD group. It becomes effective when an MTCD group is provided in the communication system. As specific examples of combinations with the restriction information, three of the following (b1) to (b3) are disclosed. For example, assume that there are an MTCD group A and an MTCD group B. (b1) The MTCD restriction information indicates the restriction information for the MTCDs belonging to the MTCD group A. (b2) MTCD restriction information is provided for each MTCD group. That is, the MTCD restriction information for the MTCD group A and the MTCD restriction information for the MTCD group B are provided separately. In that case, it is advisable to add the identifier of the MTCD group to the MTCD restriction information. (b3) The MTCD restriction information indicates the restriction information for all MTCD groups. Also, the number of groups does not have to be two.

[0152] (3) Restriction information according to the priority of the mobile terminal. It becomes effective when distinguishing whether the mobile terminal has a high priority or a low priority, rather than distinguishing whether it is an MTCD in the communication system. As specific examples of combinations with the restriction information, two of the following (c1) and (c2) are disclosed. (c1) The restriction information indicates the restriction information for the mobile terminals with a low priority. (c2) Restriction information for the mobile terminals with a high priority and restriction information for the mobile terminals with a low priority are provided. Also, the priority does not have to be binary.

[0153] As specific examples of the method for determining the MTCD restriction information, two of the following (1) and (2) are disclosed.

[0154] (1) The MTCD restriction information is determined statically. Static means, for example, determined by the performance (capability) of the base station. As specific examples, the following three cases (a1) to (a3) are disclosed. (a1) The HeNB restricts the MTCD. Base stations other than the HeNB, such as macro cells, do not restrict the MTCD. When the above restriction is predetermined, the notification of the MTCD restriction information can be omitted. (a2) Base stations with a small number of accommodable devices, for example, base stations with the number of accommodable devices less than the threshold, restrict the MTCD. Base stations with a large number of accommodable devices, for example, base stations with the number of accommodable devices greater than the threshold, do not restrict the MTCD. (a3) Base stations with a small coverage area, for example, base stations with a coverage area narrower than the threshold, restrict the MTCD. Base stations with a large coverage area, for example, base stations with a coverage area larger than the threshold, do not restrict the MTCD.

[0155] (2) The MTCD restriction information is determined quasi-statically for each base station. Quasi-static means determined by factors other than the performance of the base station, such as the installation status and operation status of the base station. Specific examples are shown below. Base stations other than the HeNB, such as macro cells, are not restricted. An HeNB installed outside the coverage area of other cells (hereinafter also referred to as "area-complementary HeNB") makes it impossible for the MTCD to camp on in order to obtain normal service. An HeNB installed within the coverage area of other cells (hereinafter also referred to as "service-providing HeNB") prohibits the MTCD from being a candidate for cell selection and reselection. When determined quasi-statically in this way, compared with the case of static determination, it can be changed according to the installation status of the base station, etc., so that a more flexible communication system can be constructed.

[0156] Specific examples of the method for notifying the MTCD restriction information from the base station to the mobile terminals under its umbrella are disclosed. As the notification information, the MTCD restriction information is notified. As a result, the mobile terminal can receive the MTCD restriction information regardless of the state of the mobile terminal, for example, regardless of whether the mobile terminal is in the standby state or the connected state. As specific examples of the case of notifying as the notification information, the following two cases (1) and (2) are disclosed.

[0157] (1) Notify by MIB. Set new parameters in the MIB. Since the MIB is received by the mobile terminal at an early stage of cell search (see step ST1204 in FIG. 12), by notifying the MTCD restriction information in the MIB, the mobile terminal can early determine whether there are restrictions.

[0158] (2) Notify by SIB. Set new parameters in the SIB. The SIB is mapped to the DL-SCH which is a downlink shared channel. The MIB in (1) is mapped to the PBCH which is a physical broadcast channel. The resources of the PBCH are limited to 4 subframes within a 40 ms interval as described above. In contrast, there is no such restriction on the DL-SCH. Therefore, by notifying the MTCD restriction information in the SIB, the restriction on the amount of information of the MTCD restriction information can be relaxed. As specific examples of notifying by the SIB, the following three of (a1) to (a3) are disclosed.

[0159] (a1) Notify by SIB1. Set new parameters in the SIB1. The SIB1 includes existing parameters related to access restriction (cellbarred, CSG-indication, CSG-identity). Therefore, by including the MTCD restriction information in the SIB1, the mobile terminal can process the parameters related to access restriction simultaneously, so that the processing of the mobile terminal can be simplified.

[0160] (a2) Notify by SIB2. Set new parameters in the SIB2. The SIB2 includes existing parameters related to access restriction (ac-BarringInfo: ACB). Therefore, by including the MTCD restriction information in the SIB2, the mobile terminal can process the parameters related to access restriction simultaneously, so that the processing of the mobile terminal can be simplified.

[0161] (a3) It is notified by SIB3, SIB4, SIB5, SIB6, SIB7, SIB8. New parameters are provided for SIB3, SIB4, SIB5, SIB6, SIB7, SIB8. SIB3, SIB4, SIB5, SIB6, SIB7, SIB8 include existing parameters related to cell reselection. Therefore, by including the MTCD restriction information in SIB3, SIB4, SIB5, SIB6, SIB7, SIB8, the parameters related to cell reselection can be processed simultaneously by the mobile terminal, so that the processing of the mobile terminal can be simplified.

[0162] When the MTCD restriction information indicates whether the MTCD in the specific example (1) is accessible, as a method for notifying the MTCD restriction information from the base station to the mobile terminals under its umbrella, the existing parameter Access Class Barring (ACB) may be used (see Non-Patent Document 2). By using the existing parameters, it is possible to avoid the complication of the communication system. Two points that require changes to the existing parameters are disclosed below in (1) and (2).

[0163] (1) In the case of ACB, which is an existing parameter, there is no distinction between the MTCD and the normal UE. Therefore, it is impossible for the base station to distinguish between the normal UE and the MTCD and restrict the operation using the parameter ACB. In the present embodiment, the ACB for the MTCD and the ACB for the normal UE are separated. As a result, the base station can distinguish between the normal UE and the MTCD and restrict the operation using the parameter ACB.

[0164] (2) 3GPP is considering avoiding congestion caused by MTCDs on the core network side (see 3GPP R3-102661 (hereinafter referred to as "Non-Patent Document 10")). The content described in Non-Patent Document 10 will be explained. When congestion occurs due to MTCDs on the core network side, the core network side designates the exclusion of access by MTCDs to the base station. However, in the method described in Non-Patent Document 10, it is not possible to designate the exclusion of access by MTCDs regardless of congestion caused by MTCDs on the core network side.

[0165] Therefore, in the present embodiment, even if congestion caused by MTCDs on the core network side does not occur, the base station is configured to notify the MTCD restriction information to the mobile terminals under its umbrella using the parameter ACB. For example, the base station is configured to notify the MTCD restriction information to the mobile terminals under its umbrella using the parameter ACB without an instruction from the core network side. Or the base station is configured to notify the MTCD restriction information to the mobile terminals under its umbrella using the parameter ACB without receiving an Overload Start from the core network side. Thus, the base station can notify the MTCD restriction information to the mobile terminals under its umbrella using the parameter ACB regardless of congestion on the core network side.

[0166] When the MTCD restriction information indicates whether the MTCD in the specific example (4) is prohibited from being a candidate for cell selection and reselection, as a method for notifying the MTCD restriction information from the base station to the mobile terminals under its umbrella, an existing parameter, cellbarred (hereinafter sometimes simply referred to as "Barred"), may be used (see Non-Patent Document 2). By using the existing parameter, it is possible to avoid complicating the communication system.

[0167] Disclose the points that need to be changed for the existing parameters. In the existing parameter Barred, there is no distinction between MTCD and normal UE. Therefore, it is impossible for the base station to distinguish between normal UE and MTCD and restrict operations using the parameter Barred. Thus, in this embodiment, Barred for MTCD and Barred for normal UE are separated. As a result, the base station can distinguish between normal UE and MTCD and restrict operations using the parameter Barred.

[0168] Also, as a method for notifying MTCD restriction information from the base station to the mobile terminals under its umbrella, an area where only MTCD decodes may be provided, and the MTCD restriction information may be mapped to that area. As a result, it becomes unnecessary for normal UE to receive the area, and it becomes unnecessary to decode the area. Therefore, it is not necessary to modify the existing 3GPP devices, and a communication system with excellent backward compatibility can be constructed.

[0169] As specific examples of the cell where the mobile terminal receives MTCD restriction information, the following two cases (1) and (2) are disclosed. (1) The cell where measurements are performed. (2) The cell that satisfies the cell selection criteria. When using the cell of specific example (2), compared with the case of using the cell of specific example (1), the number of cells that need to receive MTCD restriction information is reduced. Therefore, by using the cell of specific example (2), the processing load on the mobile terminal can be reduced. Also, low power consumption of the mobile terminal can be realized.

[0170] As specific examples of the timing when the mobile terminal reflects MTCD restriction information, the following seven cases (1) to (7) are disclosed. The specific examples disclosed below may be the timing when the mobile terminal checks MTCD restriction information.

[0171] (1) When selecting a cell. Before selecting a cell, check the MTCD restriction information to confirm whether the cell can be selected (camped on). If the cell can be selected, select the cell. If the cell cannot be selected, remove the cell from the cell selection candidates and start the operation to select another cell.

[0172] (2) When reselecting a cell. Before reselecting a cell, check the MTCD restriction information to confirm whether the cell can be reselected (camped on). If the cell can be reselected, reselect the cell. If the cell cannot be reselected, remove the cell from the cell reselection candidates and start the operation to reselect another cell.

[0173] (3) When accessing. Before accessing, check the MTCD restriction information to confirm whether the cell can be accessed. If the cell can be accessed, start the access to the cell. If the cell cannot be accessed, abort the access or start the cell reselection operation to select another accessible cell.

[0174] (4) Periodically. Receive and check the MTCD restriction information at a predetermined period.

[0175] (5) When the MTCD restriction information is changed. The change in the content of the MTCD restriction information may trigger cell reselection. For example, when the MTCD restriction information changes from "can camp on to obtain normal service" to "cannot camp on to obtain normal service", the subordinate MTCD starts the cell reselection operation to select another cell that can camp on to obtain normal service.

[0176] (6) When receiving a notification of a change in system information. A paging message may be used in the notification (see Non-Patent Document 2). This is effective when the MTCD restriction information is notified by system information (SI).

[0177] (7) The combination of the above (1) to (6).

[0178] The MTCD may reflect or confirm the MTCD restriction information. A normal UE does not have to reflect or confirm the MTCD restriction information. As a result, it is not necessary to modify the normal UE, and a communication system with excellent backward compatibility can be constructed.

[0179] When the base station does not restrict the MTCD, it does not have to notify the MTCD restriction information. The mobile terminal may determine that there is no restriction on the MTCD for a base station that does not notify the MTCD restriction information. Or, the mobile terminal may determine that a cell that does not notify the MTCD restriction information treats the MTCD and the normal UE in the same way. As a specific example, the MTCD restriction information may be notified by the HeNB. The MTCD restriction information does not have to be notified by a base station other than the HeNB, such as a macro cell. In this case, the mobile terminal may determine that there is no restriction on the MTCD for a cell that does not notify the MTCD restriction information. As a result, it is not necessary to modify a base station other than the HeNB, and a communication system with excellent backward compatibility can be constructed.

[0180] Next, with reference to FIG. 14, a specific example of the sequence of the communication system in Embodiment 1 will be described. FIG. 14 is a diagram showing the sequence of the communication system in Embodiment 1. In this operation example, as a specific example of the restriction indicated by the MTCD restriction information, a case where the MTCD in the specific example (2) can be selected as a suitable cell will be disclosed. Also, as a specific example of the method for determining the MTCD restriction information, a case where the HeNB in (a1) of the specific example (1) restricts the MTCD will be disclosed. Base stations other than HeNB, such as macro cells, etc., a case where the MTCD is not restricted will be disclosed. Also, as a cell in which the mobile terminal receives the MTCD restriction information, a case of a cell that satisfies the cell selection criteria in the specific example (2) will be disclosed. Also, as a specific example of the timing when the mobile terminal reflects the MTCD restriction information, the time of cell selection in the specific example (1) will be disclosed. Also, a case where the MTCD reflects or confirms the MTCD restriction information will be disclosed. Assume that a mobile terminal (UE) exists within the coverage of HeNB_A and is performing a cell selection operation.

[0181] In step ST1401, the UE executes cell measurement (Measurement) and proceeds to step ST1402. Specifically, as the measurement, the processes of steps ST1201, ST1202, and ST1203 in the flowchart shown in FIG. 12 described above are executed. In this operation example, it is assumed that in step ST1203, HeNB_A is selected as the best cell.

[0182] In step ST1402, the UE determines whether the measurement result in step ST1401 satisfies the cell selection criteria. In this operation example, the UE determines whether HeNB_A satisfies the cell selection criteria. If the UE determines in step ST1402 that the cell selection criteria are satisfied, it proceeds to step ST1404, and if it determines that the cell selection criteria are not satisfied, it returns to step ST1401.

[0183] In step ST1403, HeNB_A notifies the UE of the MTCD restriction information. HeNB_A notifies the mobile terminals (UEs) under its umbrella that "the MTCD cannot be selected as a suitable cell" as the MTCD restriction information.

[0184] In step ST1404, the UE receives the MTCD restriction information. Specifically, the UE receives the MTCD restriction information notified by the base station that was determined to meet the cell selection criteria in step ST1402. In this operation example, the UE receives "the MTCD cannot be selected as a suitable cell", which is the MTCD restriction information notified by HeNB_A.

[0185] In step ST1405, the UE determines whether the device itself is an MTCD. For this determination, information indicating that it is an MTCD (MTCD indicator) stored in the USIM or the like may be used. If the UE determines in step ST1405 that it is an MTCD, it proceeds to step ST1406, and if it determines that it is not an MTCD, it proceeds to step ST1407. By performing the process of step ST1405, the operation of the MTCD can be restricted in a form that differentiates it from a normal UE.

[0186] In step ST1406, the UE determines whether the cell restricts the MTCD. In this operation example, it is determined whether the MTCD can select HeNB_A as a suitable cell. If the UE determines in step ST1406 that the MTCD can select HeNB_A as a suitable cell, the process proceeds to step ST1407; if it determines that the MTCD cannot select HeNB_A as a suitable cell, the process returns to step ST1401. In this operation example, since the UE determines from the MTCD restriction information received in step ST1403 that HeNB_A cannot be selected as a suitable cell, the process returns to step ST1401. By performing the process of step ST1406, the operation of the MTCD can be restricted.

[0187] In step ST1407, the UE selects the cell as a suitable cell.

[0188] According to the above Embodiment 1, the following effects can be obtained. The base station can restrict the operation of the MTCD in a form that differentiates it from a normal UE. Specifically, the HeNB can restrict the operation of the MTCD in a form that differentiates it from a normal UE. This can solve the problem that the HeNB is occupied by the MTCD and cannot accommodate normal UEs. Therefore, the provision of services to normal UEs by the HeNB can be maintained.

[0189] Not only the HeNB described above, but also so-called local nodes such as HNB, pico eNB which is a pico cell for LTE (hereinafter may be referred to as "EUTRAN pico cell"), pico NB which is a pico cell for WCDMA (hereinafter may be referred to as "UTRAN pico cell"), relay, remote radio head (RRH), nodes for hot zone cells, etc. have a smaller coverage compared to macro cells, and the number of mobile terminals that can be accommodated is expected to be significantly smaller compared to the number of mobile terminals that can be accommodated by macro cells. From this, it is considered that the problems of Embodiment 1 also occur for these local nodes. Therefore, it is effective to solve the above problems for local nodes such as HNB, pico eNB, pico NB, relay, remote radio head, nodes for hot zone cells, etc. using Embodiment 1 of the present invention.

[0190] Also, for macro cells such as eNB and NB, there may be a case where it is desired to prioritize the handling of normal UEs compared to MTCDs. For example, it is a case where an event is held within the coverage and a large number of normal UEs are expected to be used. In such a case, it is effective to use Embodiment 1 of the present invention for macro cells etc. to ensure a margin for accommodating normal UEs and maintain the service for normal UEs.

[0191] Also, it is regarded as a problem that congestion may occur in the radio section by MTCDs or on the core network side. Also in that case, using Embodiment 1 of the present invention, the operation of MTCDs can be restricted in a form different from normal UEs. By restricting the operation of MTCDs, congestion in the radio section by MTCDs or on the core network side can be eliminated. Furthermore, while maintaining the provision of services for normal UEs, congestion in the radio section by MTCDs or on the core network side can be eliminated.

[0192] When this embodiment is used for the purpose of eliminating congestion in the radio section by MTCD or on the core network side, the following four specific examples of triggers for the base station to change the MTCD restriction information are disclosed: (1) Changes in the congestion status on the core network side. For example, congestion occurs or congestion is resolved. (2) Changes in the congestion status of the radio section. For example, congestion occurs or congestion is resolved. (3) Changes in the processing load of the base station. For example, the processing load increases or the processing load decreases. (4) Combinations of (1) to (3) above.

[0193] As specific examples of the combination of the trigger for changing the MTCD restriction information and the restriction when this embodiment is used for the purpose of eliminating congestion in the radio section by MTCD or on the core network side, the following three (1) to (3) are disclosed.

[0194] (1) The combination of the trigger and the restriction when the trigger is the change in the congestion status on the core network side in the specific example (1) of the trigger. When congestion occurs, the base station operates to tighten the restriction. When congestion is resolved, the base station operates to relax the restriction.

[0195] (2) The combination of the trigger and the restriction when the trigger is the change in the congestion status of the radio section in the specific example (2) of the trigger. When congestion occurs, the base station operates to strengthen the restriction. When congestion is resolved, the base station operates to relax the restriction.

[0196] (3) The combination of the trigger and the restriction when the trigger is the change in the processing load of the base station in the specific example (3) of the trigger. When the processing load increases, the base station operates to strengthen the restriction. When the processing load decreases, the base station operates to relax the restriction.

[0197] When this embodiment is used for the purpose of eliminating congestion in the radio section by MTCD or on the core network side, the trigger for the base station to change the MTCD restriction information does not have to be binary. As specific examples of non-binary triggers, the following two (1) and (2) are disclosed.

[0198] (1) Notify multiple values as trigger information. For the case of using 2 bits as specific trigger information, it is shown below. "11" indicates the congestion level 0 (minimum). "10" indicates the congestion level 1. "01" indicates the congestion level 2. "00" indicates the congestion level 3 (maximum). The congestion level means that the higher the number, the more severe the congestion. That is, the congestion situation becomes more severe as the congestion level increases from the minimum value "0" to "1", "2", and the maximum value "3" is the most severe.

[0199] (2) It may be a status instead of a trigger. Information indicating the congestion situation may be notified periodically. Also, if the notification of the information indicating the congestion situation disappears, it may be regarded as indicating congestion elimination.

[0200] Specific examples of the combination of trigger and restriction when the trigger for changing the MTCD restriction information is a multiple value when using this embodiment for the purpose of eliminating congestion in the radio section by the MTCD or on the core network side are disclosed below. For the case of using 2 bits as specific trigger information, it is shown below. When the trigger information is "11" and indicates the congestion level 0 (minimum), there is no restriction. When the trigger information is "10" and indicates the congestion level 1, the MTCD is prohibited from camping on to obtain normal services. When the trigger information is "01" and indicates the congestion level 2, the MTCD is prohibited from camping on to obtain limited services. When the trigger information is "00" and indicates the congestion level 3 (maximum), the MTCD is prohibited from being a candidate for cell selection and reselection.

[0201] The following discloses a specific example of a method by which the core network side notifies a base station of a trigger when using this embodiment for the purpose of eliminating congestion in a radio section by MTCD or on the core network side. For example, the core network side such as an MME or an S-GW notifies trigger information. As the trigger information, "Overload Start" and "Overload Stop" of an existing message can be used. By using an existing message, it is possible to avoid complicating the communication system. For example, the MME notifies the base station of "Overload Start" to notify that congestion has occurred on the core network side. The MME notifies the base station of "Overload Stop" to notify that the congestion on the core network side has been eliminated.

[0202] Using FIG. 15, a specific example of the sequence of a communication system when using this embodiment for the purpose of eliminating congestion in a radio section by MTCD or on the core network side will be described. FIG. 15 is a diagram showing the sequence of a communication system when using Embodiment 1 for the purpose of eliminating congestion in a radio section by MTCD or on the core network side. Since the sequence shown in FIG. 15 is similar to the sequence shown in FIG. 14, the same step numbers are assigned to the same steps, and the common description is omitted.

[0203] In this operation example, as a specific example of the restriction indicated by the MTCD restriction information, a case where the MTCD in the specific example (2) can be selected as a suitable cell will be disclosed. Also, as a specific example of the trigger for the base station to change the MTCD restriction information, a case where the change in the congestion situation on the core network side in the specific example (1) is used will be disclosed. Further, as a specific example on the core network side for notifying the trigger to the base station, a case where the MME is used will be disclosed. Also, as a specific example of the method for the core network side to notify the trigger to the base station, a case where the "Overload Start" and "Overload Stop" of the existing message are used will be disclosed. Assume that a mobile terminal (UE) exists within the coverage of eNB_A and is performing a cell selection operation. In this operation example, it is assumed that congestion has occurred on the core network side.

[0204] In step ST1501, the MME determines whether congestion has occurred on the core network side. If the MME determines in step ST1501 that congestion has occurred, it proceeds to step ST1502; if it determines that no congestion has occurred, it proceeds to step 1503. In this operation example, since it is assumed that congestion has occurred on the core network side, it proceeds to step ST1502.

[0205] In step ST1502, the MME sets "Overload Start" as the trigger information for the base station to change the MTCD restriction information to be notified to the base station. In this operation example, since it proceeds from step ST1501 to step ST1502, the MME sets "Overload Start" as the trigger information.

[0206] In step ST1503, the MME sets "Overload Stop" as the trigger information for the base station to change the MTCD restriction information to be notified to the base station.

[0207] In step ST1504, the MME notifies the eNB_A, which is the base station, of the trigger information for the base station to change the MTCD restriction information. In this operation example, "Overload Start" is notified as the trigger information.

[0208] In step ST1505, the eNB_A, which is the base station, determines whether congestion has occurred on the core network side based on the trigger information for the base station to change the MTCD restriction information received from the MME in step ST1504. As a specific example of the determination, when "Overload Start" is received as the trigger information, it is determined that congestion has occurred on the core network side. When "Overload Stop" is received as the trigger information, it is determined that the congestion on the core network side has been resolved, that is, no congestion has occurred. If the eNB_A, which is the base station, determines in step ST1505 that congestion has occurred, it proceeds to step ST1506. If it determines that no congestion has occurred, it proceeds to step ST1507. In this operation example, since "Overload Start" is received in step ST1504, it is determined that congestion has occurred on the core network side, and the process proceeds to step ST1506.

[0209] In step ST1506, the base station sets "MTCD cannot be selected as a suitable cell" as the MTCD restriction information. In step ST1507, the base station sets "MTCD can be selected as a suitable cell" as the MTCD restriction information. By performing the process of step ST1506 or step ST1507, the MTCD restriction information can be used to eliminate congestion in the radio section by the MTCD or on the core network side.

[0210] In step ST1508, the base station notifies the MTCD restriction information to the mobile terminals (UEs) under its umbrella. Thereafter, the processes of steps ST1404 to ST1407 are performed in the same manner as the example shown in FIG. 14.

[0211] Embodiment 1, Variation 1 The problem to be solved in Variation 1 of Embodiment 1 will be described below. When the aforementioned Embodiment 1 is used, the following problems occur. For example, consider the case of a privately-owned HeNB. When Embodiment 1 is used, there is a problem that the same privately-owned MTCD as the HeNB has its operation restricted to the HeNB.

[0212] The solution in Variation 1 of Embodiment 1 is shown below. In this variation, the explanation will focus on the parts different from the solution in Embodiment 1, and for the parts not explained, it will be the same as in Embodiment 1.

[0213] Register the MTCD that does not want to be restricted with the same CSG-ID as the base station that does not want to be restricted. The base station notifies the mobile terminals under its umbrella of MTCD restriction information (hereinafter sometimes referred to as "unregistered MTCD restriction information") for MTCDs not registered in the same CSG as the self-base station. The unregistered MTCD restriction information corresponds to the unregistered restriction information.

[0214] Among the mobile terminals that have received the unregistered MTCD restriction information, the MTCDs not registered in the same CSG as the base station (hereinafter sometimes referred to as "CSG-unregistered MTCDs") operate according to the restrictions indicated by the unregistered MTCD restriction information. Among the mobile terminals that have received the unregistered MTCD restriction information, the mobile terminals that are not CSG-unregistered MTCDs, that is, normal UEs, and the MTCDs registered in the same CSG as the base station do not operate according to the restrictions indicated by the unregistered MTCD restriction information. Among the mobile terminals that have received the unregistered MTCD restriction information, the mobile terminals that are not CSG-unregistered MTCDs may operate normally.

[0215] As specific examples of the restrictions indicated by the unregistered MTCD restriction information, the following seven (1) to (7) are disclosed.

[0216] (1) Whether an MTCD unregistered with the same CSG as the home base station can access. As specific examples of access, the following five cases (a1) to (a5) are disclosed. (a1) Uplink control data transmission. (a2) Uplink traffic data transmission. This may be the transmission of user data. (a3) RACH transmission. (a4) Transmission of an RRC Connection Request. (a5) Combinations of (a1) to (a4) above.

[0217] (2) Whether an MTCD unregistered with the same CSG as the home base station can camp on to obtain normal services. In other words, whether the MTCD can be selected as a Suitable Cell.

[0218] (3) Whether an MTCD unregistered with the same CSG as the home base station can camp on to obtain limited services. In other words, whether the MTCD can be selected as an Acceptable cell. As specific examples of limited services, the following four cases (b1) to (b4) are disclosed. (b1) Making an emergency call. (b2) Receiving ETWS. (b3) Receiving CMAS. (b4) Combinations of (b1) to (b3) above.

[0219] (4) Whether an MTCD unregistered with the same CSG as the home base station is prohibited from being a candidate for cell selection and reselection. In other words, whether the cell is a Barred cell for the MTCD.

[0220] (5) Whether an MTCD unregistered with the same CSG as the home base station is prohibited from roaming in.

[0221] (6) Whether an MTCD unregistered with the same CSG as the home base station is prohibited from handing over in.

[0222] (7) Combinations of (1) to (6) above.

[0223] Disclose a specific example of a method for notifying unregistered MTCD restriction information from a base station to a mobile terminal under its umbrella. As notification information, unregistered MTCD restriction information is notified. Thereby, an effect that the mobile terminal can receive the unregistered MTCD restriction information regardless of the state of the mobile terminal, for example, regardless of whether the mobile terminal is in a standby state or a connected state, can be obtained. The specific example in the case of notifying as notification information shall be the same as in Embodiment 1.

[0224] When the unregistered MTCD restriction information indicates whether an unregistered MTCD in the same CSG as the home base station of the specific example (1) can access, as a method for notifying MTCD restriction information from the base station to the mobile terminal under its umbrella, an existing parameter, access class barring (ACB), may be used (see Non-Patent Document 2). By using the existing parameter, it is possible to avoid complication of the communication system.

[0225] Disclose the following two points (1) and (2) as the points where changes are required for the existing parameters.

[0226] (1) In the existing ACB, there is no distinction between an unregistered MTCD in the same CSG as the home base station and a mobile terminal that is not an unregistered MTCD in the same CSG as the home base station. Therefore, it is impossible to use the parameter ACB for the base station to distinguish between an MTCD registered in the same CSG as the home base station and a mobile terminal that is not an unregistered MTCD in the same CSG as the home base station and restrict the operation.

[0227] Therefore, in this modification example, the ACB for an unregistered MTCD in the same CSG as the home base station and the ACB for a mobile terminal that is not an unregistered MTCD in the same CSG as the home base station are separated. Thereby, it becomes possible for the base station to use the parameter ACB to distinguish between an unregistered MTCD in the same CSG as the home base station and a mobile terminal that is not an unregistered MTCD in the same CSG as the home base station and restrict the operation.

[0228] (2) 3GPP is considering congestion avoidance by MTCDs on the core network side (see Non-Patent Document 10). The content described in Non-Patent Document 10 will be explained. When congestion occurs due to MTCDs on the core network side, the core network side designates the exclusion of access by MTCDs to the base station. However, in the method described in Non-Patent Document 10, it is not possible to designate the exclusion of access by MTCDs not registered in the same CSG as the home base station, regardless of congestion caused by MTCDs on the core network side.

[0229] Therefore, in this modified example, even if congestion due to MTCDs on the core network side does not occur, the base station is configured to notify the mobile terminals under its umbrella of unregistered MTCD restriction information using ACB. For example, the base station is configured to notify the mobile terminals under its umbrella of unregistered MTCD restriction information using the parameter ACB even without an instruction from the core network side. Or the base station is configured to notify the mobile terminals under its umbrella of MTCD restriction information for MTCDs not registered in the same CSG as the home base station using the parameter ACB even without receiving an Overload Start from the core network side. As a result, the base station can notify the mobile terminals under its umbrella of restriction information for unregistered MTCDs using the parameter ACB, regardless of congestion on the core network side.

[0230] When the unregistered MTCD restriction information indicates whether an MTCD not registered in the same CSG as the home base station in the specific example (4) is prohibited from being a candidate for cell selection and reselection, as a method for notifying the unregistered MTCD restriction information from the base station to the mobile terminals under its umbrella, an existing parameter, cellbarred (sometimes simply referred to as "Barred"), may be used (see Non-Patent Document 2). By using an existing parameter, it is possible to avoid complicating the communication system.

[0231] Disclose the points that need to be changed for the existing parameters. In the existing Barred, there is no distinction between an MTCD not registered in the same CSG as the home base station and a mobile terminal not being an MTCD not registered in the same CSG as the home base station. Therefore, it is impossible to use the parameter Barred for the base station to distinguish between an MTCD not registered in the same CSG as the home base station and a mobile terminal not being an MTCD not registered in the same CSG as the home base station and restrict the operation.

[0232] Therefore, in this modification example, the Barred for an MTCD not registered in the same CSG as the home base station and the Barred for a mobile terminal not being an MTCD not registered in the same CSG as the home base station are separated. As a result, the base station can use the parameter Barred to distinguish between an MTCD not registered in the same CSG as the home base station and a mobile terminal not being an MTCD not registered in the same CSG as the home base station and restrict the operation.

[0233] Next, with reference to FIG. 16, a specific example of the sequence of the communication system in Modification Example 1 of Embodiment 1 will be described. FIG. 16 is a diagram showing the sequence of the communication system in Modification Example 1 of Embodiment 1. Since the sequence shown in FIG. 16 is similar to the sequence shown in FIG. 14, the same step numbers are assigned to the same steps, and the common description is omitted.

[0234] In this operation example, as a specific example of the restrictions indicated by the unregistered MTCD restriction information, the case where the MTCD of the specific example (2) can or cannot be selected as a suitable cell will be disclosed. Also, as a specific example of the method for determining the unregistered MTCD restriction information, the case where the HeNB restricts unregistered MTCDs in the same CSG as its own base station will be disclosed. Base stations that are not HeNBs, such as macro cells, etc., will disclose the case where they do not restrict unregistered MTCDs in the same CSG as their own base station. Also, the cell in which the mobile terminal receives the MTCD restriction information will be disclosed for the case of a cell that satisfies the cell selection criteria. Also, as a specific example of the timing when the mobile terminal reflects the unregistered MTCD restriction information, the time of cell selection will be disclosed. Also, the case where the MTCD reflects or confirms the unregistered MTCD restriction information will be disclosed. Assume that a mobile terminal (UE) exists within the coverage area of HeNB_A, which is a base station, and is performing a cell selection operation.

[0235] In this modified example, in the same manner as in the aforementioned Embodiment 1, after the processes of step ST1401 and step ST1402 shown in FIG. 14 are performed, the process proceeds to step ST1601. In step ST1601, HeNB_A notifies the unregistered MTCD restriction information as the MTCD restriction information. In this modified example, HeNB_A notifies the underling mobile terminals (UEs) that "unregistered MTCDs in the same CSG as its own base station cannot be selected as suitable cells" as the unregistered MTCD restriction information.

[0236] In step ST1602, HeNB_A notifies the UE of the CSG identity (CSG-ID) of its own base station. Then, in the same manner as in Embodiment 1, the processes of step ST1404 and step ST1405 shown in FIG. 14 are performed. Among the UEs, the MTCD proceeds to step ST1603, and the UEs other than the MTCD proceed to step ST1407.

[0237] In step ST1603, the MTCD determines whether it is registered in the same CSG as HeNB_A which is a HeNB. For this determination, a whitelist stored in a USIM or the like may be used. In step ST1603, if it is determined that the MTCD is registered in the same CSG as the HeNB, the process proceeds to step ST1407. If it is determined that the MTCD is not registered in the same CSG as the HeNB, that is, if it is determined as unregistered, the process proceeds to step ST1604. By performing the process of step 1603, the base station can restrict the operation of the MTCD that is not registered in the same CSG as the base station itself, in a form that distinguishes it from the MTCD registered in the same CSG as the base station itself.

[0238] In step ST1604, the UE determines whether the base station is restricting the operation of the MTCD that is not registered in the same CSG as the base station itself. In this operation example, it is determined whether the MTCD that is not registered in the same CSG as HeNB_A can be selected as a suitable cell. If the UE determines that the base station allows the MTCD that is not registered in the same CSG as the base station itself to be selected as a suitable cell, the process proceeds to step ST1407. If it is determined that the MTCD that is not registered in the same CSG as the base station itself cannot be selected as a suitable cell, the process returns to step ST1401. By performing the process of step ST1604, the base station can restrict the operation of the MTCD that is not registered in the same CSG as the base station itself.

[0239] According to Modification Example 1 of Embodiment 1 above, in addition to the effects of Embodiment 1, the following effects can be obtained. The base station can restrict the operation of the MTCD that is not registered in the same CSG as the base station itself, in a form that distinguishes it from a normal UE and the MTCD registered in the same CSG as the base station itself. For example, using this modification example, the HeNB can restrict the operation of the MTCD that is not registered in the same CSG as the base station itself, in a form that distinguishes it from a normal UE and the MTCD registered in the same CSG as the base station itself.

[0240] This can solve the problem that the HeNB is occupied by an MTCD unregistered in the same CSG as the home base station, making it impossible to accommodate normal UEs or MTCDs registered in the same CSG as the home base station. Therefore, the HeNB can maintain the provision of services to MTCDs registered in the same CSG as the HeNB and normal UEs.

[0241] This modified example can be used in combination with the aforementioned Embodiment 1.

[0242] Embodiment 1 Modified Example 2. The handover method disclosed in Non-Patent Document 1 will be described with reference to FIG. 17. FIG. 17 is a diagram showing the sequence of a communication system related to the handover method disclosed in Non-Patent Document 1.

[0243] In step ST1701, the source eNB, which is the serving base station, notifies measurement control information to a mobile terminal (UE) in a connected state.

[0244] In step ST1702, the mobile terminal performs cell measurements according to the measurement control information received in step ST1701.

[0245] In step ST1703, the mobile terminal notifies measurement reports to the source eNB, which is the serving base station, according to the measurement control information received in step ST1701.

[0246] In step ST1704, the source eNB, which is the serving base station, performs decision processing related to handover (hereinafter sometimes referred to as "handover decision processing") in consideration of the measurement reports received in step ST1703. Specific examples of the content of the handover decision processing include the decision on whether to perform handover and the decision on the target base station (hereinafter also referred to as "target eNB").

[0247] In step ST1705, the source eNB notifies the target eNB determined in step ST1704 of a Handover Request.

[0248] In step ST1706, the target eNB that received the handover request in step ST1705 determines whether it can accept the handover. If the target eNB determines in step ST1706 that it can accept the handover, it proceeds to step ST1707; if it determines that it cannot accept the handover, it proceeds to step ST1708.

[0249] In step ST1707, the target eNB sets a notification of the resources prepared for handover acceptance as a response message to the handover request from the source eNB.

[0250] In step ST1708, the target eNB sets a handover acceptance rejection as a response message to the handover request from the source eNB.

[0251] In step ST1709, the target eNB notifies the source eNB of a response message to the handover request.

[0252] In step ST1710, the source eNB determines whether the target eNB can accept the handover. For this determination, the response message to the handover request received from the target eNB in step ST1709 can be used. If the source eNB determines in step ST1710 that the target eNB can accept the handover, it proceeds to step ST1711; if it determines that the target eNB cannot accept the handover, it does not execute step ST1711.

[0253] In step ST1711, the source eNB notifies the mobile terminal that has notified the measurement report in step ST1703 of mobility control information.

[0254] In step ST1712, the mobile terminal detaches from the source eNB. In step ST1713, the mobile terminal establishes synchronization with the target eNB according to the mobility control information received in step ST1711.

[0255] Regarding the first problem to be solved in Modification 2 of Embodiment 1, it will be described below. When the above-described Embodiment 1 is used, the following problems occur. Consider the case where the mobile terminal in the connected state is an MTCD. Suppose there is a cell that restricts the MTCD around the serving base station of the MTCD. For example, suppose the MTCD is prohibited from handing over.

[0256] In the handover method shown in FIG. 17, the target eNB does not make a handover acceptance determination according to the MTCD restriction information of the cell in the determination of whether the handover in step ST1706 is acceptable. Therefore, even when the MTCD is restricted, if other conditions are met, the target eNB determines that the handover is acceptable. In that case, as shown in step ST1711 of FIG. 17 described above, mobility control information with the cell that restricts the MTCD as the target cell is notified from the serving base station to the MTCD.

[0257] The MTCD will be notified of a handover instruction from the serving cell to the cell that restricts the MTCD. The MTCD cannot determine whether it should handle the cell as the target cell that is the handover destination according to the instruction of the serving cell or should follow the MTCD restriction information notified from the cell. Thus, a problem occurs in that the communication system becomes unstable.

[0258] The solution to the first problem in Modification Example 2 of Embodiment 1 (hereinafter also referred to as the "first solution") is shown below. In this solution, the description will focus on the parts different from the solution in Embodiment 1, and for the parts not described, it shall be the same as in Embodiment 1.

[0259] The target eNB makes a handover acceptance possibility determination for the mobile terminal according to the MTCD restriction information of the cell. The target eNB may also make a handover acceptance possibility determination for the MTCD according to the MTCD restriction information of the cell. On the other hand, the target eNB may not make a handover acceptance possibility determination for the normal UE according to the MTCD restriction information of the cell.

[0260] Six specific examples (1) to (6) below are disclosed as specific examples of the handover acceptance possibility determination of the target eNB.

[0261] (1) Specific example when the MTCD restriction information indicates whether access to the MTCD is possible. When the MTCD restriction information indicates that access to the MTCD is possible, it is determined that handover acceptance is possible. When the MTCD restriction information indicates that access to the MTCD is impossible, it is determined that handover acceptance is impossible.

[0262] (2) Specific example when the MTCD restriction information indicates whether it can be selected as a suitable cell. When the MTCD restriction information indicates that it can be selected as a suitable cell, it is determined that handover acceptance is possible. When the MTCD restriction information indicates that it cannot be selected as a suitable cell, it is determined that handover acceptance is impossible.

[0263] (3) Specific examples when the MTCD restriction information indicates whether it is selectable as an acceptable cell. When the MTCD restriction information indicates that it is selectable as an acceptable cell, it is determined that handover is acceptable. When the MTCD restriction information indicates that it is not selectable as an acceptable cell, it is determined that handover is unacceptable.

[0264] (4) Specific examples when the MTCD restriction information indicates whether it is prohibited as a candidate for cell selection and reselection. When the MTCD restriction information indicates that it is not prohibited as a candidate for cell selection and reselection, it is determined that handover is acceptable. When the MTCD restriction information indicates that it is prohibited as a candidate for cell selection and reselection, it is determined that handover is unacceptable.

[0265] (5) Specific examples when the MTCD restriction information indicates whether the MTCD is prohibited from roaming in. When the MTCD restriction information indicates that the MTCD is not prohibited from roaming in, it is determined that handover is acceptable. When the handover to the cell is not roaming and the MTCD restriction information indicates that the MTCD is prohibited from roaming in, it is determined that handover is acceptable. When the handover to the cell is roaming and the MTCD restriction information indicates that the MTCD is prohibited from roaming in, it is determined that handover is unacceptable.

[0266] (6) Specific examples when the MTCD restriction information indicates whether the MTCD is prohibited from handing over in. When the MTCD restriction information indicates that the MTCD is not prohibited from handing over in, it is determined that handover is acceptable. When the MTCD restriction information indicates that the MTCD is prohibited from handing over in, it is determined that handover is unacceptable.

[0267] A specific example of a method for the source eNB to determine whether a mobile terminal is an MTCD is disclosed below. In 3GPP, an MTCD indicator is included in the UE Context (see 3GPP TS23.401 V10.1.0 (hereinafter referred to as "Non-Patent Document 11")). The target eNB may determine whether the mobile terminal is an MTCD using the UE Context received from the source eNB or the MME in the handover preparation process. Therefore, when the MTCD indicator is included in the UE Context, the source eNB determines that the mobile terminal is an MTCD, and when the MTCD indicator is not included in the UE Context, the source eNB determines that the mobile terminal is a normal UE.

[0268] According to the first solution in the second modification of Embodiment 1 described above, since the target eNB makes a handover acceptance determination according to the MTCD restriction information of the cell, it is possible to prevent the MTCD from being notified of a handover instruction from the serving cell to the cell that restricts the MTCD. Therefore, it is possible to prevent the communication system from becoming unstable.

[0269] Even when the first solution in the second modification of Embodiment 1 described above is used, the following problems occur. Consider the case where a mobile terminal in a connected state is an MTCD. Assume that there is a cell that restricts the MTCD around the serving base station of the MTCD. For example, assume that the MTCD is prohibited from handing over as a restriction.

[0270] Even when the first solution in the second modification of the foregoing Embodiment 1 is used, since the source eNB, which is the serving base station, does not perform handover determination processing according to the MTCD restriction information of the cell, even when the target eNB restricts the MTCD, the handover request is notified in step ST1705. This handover request will surely be rejected when the target eNB restricts the MTCD. In this way, a wasteful handover request notification that always results in a handover rejection because the target eNB restricts the MTCD occurs at the source eNB.

[0271] With the occurrence of the wasteful handover request notification at this source eNB, the reception of the wasteful handover request at the target eNB and the determination of whether the target eNB can accept the wasteful handover occur. Therefore, there arises a problem that the processing load of the base station increases and the handover control delay increases (hereinafter sometimes referred to as the "second problem").

[0272] A solution to the second problem in the second modification of Embodiment 1 (hereinafter also referred to as the "second solution") is shown below. In this solution, the description will focus on the parts different from the solution in Embodiment 1, and for the parts not described, it is the same as in Embodiment 1.

[0273] The mobile terminal notifies the serving base station of the MTCD restriction information of the cell that is the target of the measurement report. The serving base station that has received the MTCD restriction information performs handover determination processing in consideration of the restriction indicated by the MTCD restriction information of the cell that is the target of the measurement report. For example, the serving base station that has received the MTCD restriction information may determine the target cell in consideration of the restriction indicated by the MTCD restriction information of the cell that is the target of the measurement report.

[0274] Also, the serving base station that has received the MTCD restriction information may perform handover decision processing for the MTCD in consideration of the restrictions indicated by the MTCD restriction information of the target cell of the measurement report. For example, the serving base station that has received the MTCD restriction information may determine the target cell for the MTCD in consideration of the restrictions indicated by the MTCD restriction information of the target cell of the measurement report. In this case, the serving base station will perform handover decision processing for the MTCD restricted by the MTCD restriction information in consideration of the restrictions indicated by the MTCD restriction information. For normal UEs not restricted by the MTCD restriction information, the serving base station may perform handover decision processing assuming that they are not restricted by the MTCD restriction information. This can reduce the processing load on normal UEs of the serving base station.

[0275] A specific example of a method for the serving base station to determine whether the mobile terminal is an MTCD is disclosed below. In 3GPP, an MTCD indicator is included in the UE Context (see Non-Patent Document 11). Therefore, if the MTCD indicator is included in the UE Context, the serving base station determines that the mobile terminal is an MTCD, and if the MTCD indicator is not included in the UE Context, the serving base station determines that the mobile terminal is a normal UE.

[0276] As specific examples of cells where the mobile terminal receives MTCD restriction information during measurement, the following two cases (1) and (2) are disclosed. (1) The cell where measurement is performed. (2) The target cell of the measurement report. In the case of specific example (2), compared with specific example (1), the number of cells that need to receive MTCD restriction information is reduced. This can reduce the processing load of the mobile terminal, thus achieving low power consumption of the mobile terminal.

[0277] As specific examples of the mobile terminal that notifies the serving base station of the MTCD restriction information of the target cell of the measurement report, the following three cases (1) to (3) are disclosed.

[0278] (1) All mobile terminals.

[0279] (2) Only MTCDs. Even if normal UEs do not need to notify, it may be acceptable. As a result, only MTCDs restricted by MTCD restriction information will notify the MTCD restriction information. Therefore, the serving base station can determine that mobile terminals that have not notified MTCD restriction information are normal UEs, and assume that they are not restricted by the target cell for measurement reports, and can perform handover decision processing. Normal UEs do not need to receive MTCD restriction information and notify the serving base station. As a result, the processing load on normal UEs can be reduced, and low power consumption of normal UEs can be achieved.

[0280] (3) When the serving base station requests notification of MTCD restriction information of the target cell for measurement reports, the mobile terminal receives and notifies the MTCD restriction information. As a result, in cases where the serving cell does not perform handover decision processing considering the restrictions indicated by the MTCD restriction information, etc., the mobile terminal does not need to perform unnecessary notifications. Therefore, it is possible to construct a flexible communication system. The request for notification of MTCD restriction information may be made by the serving base station based on measurement control information. As a result, parameters related to measurement can be processed simultaneously by the mobile terminal, and the processing of the mobile terminal can be simplified.

[0281] Specific examples of methods for a mobile terminal to notify MTCD restriction information to the serving cell are disclosed as the following three cases (1) to (3).

[0282] (1) Perform it together with the measurement report. It may be simultaneous with the measurement report. It may be reported as part of the parameters in the measurement report. As a result, parameters related to handover decision processing can be processed simultaneously by the serving base station, and the processing of the serving base station can be simplified.

[0283] (2) It is carried out together with the notification of proximity indication disclosed in Non-Patent Document 2. It may also be simultaneous with the notification of proximity indication. It may be reported as part of the parameters within the proximity indication. Proximity indication means that a mobile terminal enters or leaves the vicinity of a cell existing in the whitelist within the mobile terminal. Therefore, by performing the notification of MTCD restriction information together with the notification of proximity indication, the serving cell can know that the mobile terminal exists near the cell where it is registered and the MTCD restriction information of that cell. As a result, the serving cell can simultaneously process the parameters related to the handover decision process, so that the processing of the serving base station can be simplified. The MTCD restriction information may be notified together with the indicator of the corresponding cell (also referred to as the cell identity). The cell indicator may be PCI or GCI. By notifying together with the cell indicator, the serving cell can determine which cell's MTCD restriction information it is even when proximity indications for multiple cells are notified.

[0284] (3) It is notified as a new message separate from the existing measurement report and proximity indication. As a specific example, it is notified periodically. The MTCD restriction information may be notified together with the indicator of the corresponding cell. The cell indicator may be PCI or GCI. By notifying together with the cell indicator, the serving base station can determine which cell's MTCD restriction information it is.

[0285] As specific examples of the handover decision process of the serving base station that has received the MTCD restriction information, considering the restrictions indicated by the MTCD restriction information, the following six items (1) to (6) are disclosed.

[0286] (1) Specific examples when the MTCD restriction information indicates whether access to the MTCD is possible. When the MTCD restriction information indicates that access to the MTCD is possible, it is determined that handover with the cell as the target cell is possible. It may also be determined that the cell can be selected as the target cell. When the MTCD restriction information indicates that access to the MTCD is impossible, it is determined that handover with the cell as the target cell is impossible. It may also be determined that the cell cannot be selected as the target cell.

[0287] (2) Specific examples when the MTCD restriction information indicates whether it can be selected as a suitable cell. When the MTCD restriction information indicates that it can be selected as a suitable cell, it is determined that handover with the cell as the target cell is possible. It may also be determined that the cell can be selected as the target cell. When the MTCD restriction information indicates that it cannot be selected as a suitable cell, it is determined that handover with the cell as the target cell is impossible. It may also be determined that the cell cannot be selected as the target cell.

[0288] (3) Specific examples when the MTCD restriction information indicates whether it can be selected as an acceptable cell. When the MTCD restriction information indicates that it can be selected as an acceptable cell, it is determined that handover with the cell as the target cell is possible. It may also be determined that the cell can be selected as the target cell. When the MTCD restriction information indicates that it cannot be selected as an acceptable cell, it is determined that handover with the cell as the target cell is impossible. It may also be determined that the cell cannot be selected as the target cell.

[0289] (4) Specific examples when the MTCD restriction information indicates whether the MTCD is prohibited as a candidate for cell selection and reselection. When the MTCD restriction information indicates that the MTCD is not prohibited as a candidate for cell selection and reselection, it is determined that handover with the cell as the target cell is possible. It may also be determined that the cell can be selected as the target cell. When the MTCD restriction information indicates that the MTCD is prohibited as a candidate for cell selection and reselection, it is determined that handover with the cell as the target cell is impossible. It may also be determined that the cell cannot be selected as the target cell.

[0290] (5) Specific examples when the MTCD restriction information indicates whether the MTCD is prohibited from roaming in. When the MTCD restriction information indicates that the MTCD is not prohibited from roaming in, it is determined that handover with the cell as the target cell is possible. It may also be determined that the cell can be selected as the target cell. When the handover to the cell is not roaming and the MTCD restriction information indicates that the MTCD is prohibited from roaming in, it is determined that handover with the cell as the target cell is possible. It may also be determined that the cell can be selected as the target cell. When the handover to the cell is roaming and the MTCD restriction information indicates that the MTCD is prohibited from roaming in, it is determined that handover with the cell as the target cell is impossible. It may also be determined that the cell cannot be selected as the target cell.

[0291] (6) Specific examples of the case where the MTCD restriction information indicates whether the MTCD is prohibited from handing over. When the MTCD restriction information indicates that the MTCD is not prohibited from handing over, it is determined that handover to the cell as the target cell is possible. It may be determined that the cell can be selected as the target cell. When the MTCD restriction information indicates that the MTCD is prohibited from handing over, it is determined that handover to the cell as the target cell is impossible. It may be determined that the cell cannot be selected as the target cell.

[0292] Next, with reference to FIGS. 18 and 19, a specific example of the sequence of the communication system in the second solution in Modification 2 of Embodiment 1 will be described. FIGS. 18 and 19 are diagrams showing the sequence of the communication system in the second solution in Modification 2 of Embodiment 1. FIG. 18 and FIG. 19 are connected at the position of the boundary line BL1. Since the sequences shown in FIGS. 18 and 19 are similar to the sequences shown in FIGS. 14 and 17, the same step numbers are assigned to the same steps, and the common description is omitted.

[0293] In this operation example, it is assumed that the MTCD with eNB_1 as the serving base station (source eNB) is moving closer to HeNB_A. Also, it is assumed that the measurement control information for the mobile terminal includes HeNB_A as the measurement target. As a specific example of the restriction indicated by the MTCD restriction information of HeNB_A, the case where the MTCD cannot be selected as a suitable cell is disclosed. Also, as a specific example of the cell in which the mobile terminal receives the MTCD restriction information during measurement, the target cell of the measurement report is disclosed. Also, as a specific example of the method by which the mobile terminal notifies the serving cell of the MTCD restriction information, the case of reporting as part of the parameters in the measurement report is disclosed. Also, the case where the serving base station that has received the MTCD restriction information performs handover determination processing for the MTCD in consideration of the restriction indicated by the MTCD restriction information of the target cell of the measurement report is disclosed.

[0294] In step ST1801, eNB_1 notifies the connected mobile terminal (UE) of measurement control information. The measurement control information includes HeNB_A as a measurement object. The carrier frequency of HeNB_A may be included in the measurement control information as a measurement object.

[0295] In step ST1802, the mobile terminal performs cell measurement according to the measurement control information received in step ST1801. The mobile terminal performs measurement of HeNB_A according to the measurement control information. The mobile terminal may perform measurement of the carrier frequency of HeNB_A according to the measurement control information.

[0296] In step ST1803, the mobile terminal determines whether the cell for which the measurement has been performed is the target cell for measurement reporting. This determination uses the measurement control information received in step ST1801. In this operation example, in step ST1803, the mobile terminal determines whether HeNB_A is the target cell for measurement reporting. If the mobile terminal determines that it is the target cell for measurement reporting, it proceeds to step ST1404; if it determines that it is not the target cell for measurement reporting, it returns to step ST1802. In this operation example, since the mobile terminal is moving closer to HeNB_A, it is determined that HeNB_A is the target cell for measurement reporting. Therefore, in step ST1803, the mobile terminal determines that HeNB_A is the target cell for measurement reporting and proceeds to step ST1404.

[0297] After the processing of step ST1404, in step ST1804, the mobile terminal notifies eNB_1 of Measurement Reports according to the measurement control information received in step ST1801. In this operation example, the mobile terminal notifies eNB_1 of the measurement report of HeNB_A. The measurement report includes the MTCD restriction information of HeNB_A. As the MTCD restriction information of HeNB_A, "MTCD cannot be selected as a Suitable Cell" is included.

[0298] In step ST1805, eNB_1 determines whether the mobile terminal that has notified the measurement report in step ST1804 is an MTCD. For this determination, the MTCD indicator in the UE Context may be used. In step ST1805, if eNB_1 determines that the mobile terminal is an MTCD, it proceeds to step ST1806, and if it determines that the mobile terminal is not an MTCD, it proceeds to step ST1704. By performing the processing of step ST1805, the handover decision processing for the MTCD can be performed in a form that distinguishes it from the normal UE according to the restrictions indicated by the MTCD restriction information.

[0299] In step ST1806, eNB_1 determines whether the target cell can be selected as the target cell for the measurement report. Specific examples of this determination are disclosed below. The determination is based on the MTCD restriction information of the target cell of the measurement report included in the measurement report received in step ST1804.

[0300] Specifically, when the MTCD restriction information indicates that the MTCD can be selected as a Suitable Cell, it is determined that the cell can be selected as the target cell. When the MTCD restriction information indicates that the MTCD cannot be selected as a Suitable Cell, it is determined that the cell cannot be selected as the target cell.

[0301] If, in step ST1806, eNB_1 determines that it is possible to select a target cell, it proceeds to step ST1704. If it determines that it is not possible to select a target cell, it does not execute the processes of step ST1704 and step ST1705.

[0302] If the processes of step ST1704 and step ST1705 are not executed, eNB_1 does not receive a response message to the handover request from HeNB_A in step ST1709. Therefore, in step ST1711, eNB_1 does not notify the mobile terminal, which reported a measurement report in step ST1804, of Mobility Control Information.

[0303] In this operation example, in step ST1804, eNB_1 receives, as the MTCD restriction information of HeNB_A, which is the target cell for the measurement report, "not selectable as a Suitable Cell for MTCD". Therefore, in step ST1806, eNB_1 determines that it is not possible to select the cell as a target cell and does not execute the processes of step ST1704 and step ST1705.

[0304] By performing the process of step ST1806 in this way, it is possible to reduce unnecessary notifications of handover requests that will surely result in handover rejection because the target eNB restricts the MTCD.

[0305] By the second solution in the second modification of Embodiment 1, the following effects can be obtained. The serving base station can perform handover determination processing according to the MTCD restriction information of the candidate cell of the handover destination. As a result, it is possible to reduce the notification of unnecessary handover requests that would always result in handover rejection because the candidate cell of the handover destination restricts MTCD. By reducing the notification of unnecessary handover requests in this serving cell, it is possible to reduce the reception of unnecessary handover requests at the target eNB and the determination of whether the target eNB can accept an unnecessary handover. Therefore, since the processing load of the base station can be reduced, the control delay of handover can be reduced.

[0306] The serving base station can use the MTCD restriction information of the target cell of the received measurement report for the following purposes. If it can be determined from the MTCD restriction information that the MTCD cannot select the cell as the target cell, the serving base station adjusts the measurement control information of the mobile terminal that has performed the measurement report if the mobile terminal is the MTCD. Among the mobile terminals under its umbrella, the measurement control information for the MTCD may be adjusted. Among the mobile terminals under its umbrella, the measurement control information of the MTCD in the connected state may be adjusted. A specific example of the adjustment of the measurement control information is to exclude the cell from the measurement target. As a result, it becomes possible to reduce the measurement by the MTCD for a cell that cannot be selected as the target cell. Therefore, low power consumption of the MTCD can be achieved.

[0307] As specific examples of a method for excluding a cell from a measurement target, the following two cases (1) and (2) are disclosed. (1) If a cell that restricts MTCD is included in the list of measurement target cells (also referred to as Listed cells or Neighboring cells) in the measurement control information disclosed in Non-Patent Document 2, the cell is deleted from the list. (2) A cell that restricts MTCD is included in the blacklist disclosed in Non-Patent Document 2. Cells listed in the blacklist are excluded from event evaluation and measurement reporting.

[0308] In the existing blacklist, there is no distinction between MTCD and normal UEs. In this modification example, the blacklist for MTCD and the blacklist for normal UEs may be separated. This enables the base station to use the blacklist to distinguish between normal UEs and MTCD and restrict operations accordingly.

[0309] In addition, this modification example can be applied to the ACB information notified from each cell disclosed in Non-Patent Document 2. As application examples, the following two cases (1) and (2) are disclosed. The information indicated by the ACB information does not have to be the MTCD restriction information shown in Embodiment 1 and Modification Example 1 of Embodiment 1.

[0310] (1) The mobile terminal notifies the serving base station of the ACB information of the measurement reporting target cell. The serving base station that has received the ACB information performs handover decision processing in consideration of the ACB information of the measurement reporting target cell. The serving base station that has received the ACB information may determine the target cell in consideration of the restrictions indicated by the ACB information of the measurement reporting target cell.

[0311] A specific example of the handover decision process is disclosed below. For a cell whose access is not restricted by the ACB information, it is determined that handover using the cell as the target cell is possible. It may also be determined that the cell can be selected as the target cell. For a cell whose access is restricted by the ACB information, it is determined that handover using the cell as the target cell is impossible. It may also be determined that the cell cannot be selected as the target cell.

[0312] As specific examples of the ACB information when access is restricted by the ACB information, the following two cases (a1) and (a2) are disclosed. (a1) The case where the access probability is "0". (a2) The case where the access probability is low. The case where the access probability is lower than the threshold value.

[0313] According to Application Example (1), the serving base station can perform a handover decision process according to the ACB information of the candidate cells for the handover destination. Therefore, it is possible to reduce the notification of unnecessary handover requests that are always rejected due to the candidate cells for the handover destination being access-restricted. By reducing the notification of unnecessary handover requests in this serving cell, it is possible to reduce the reception of unnecessary handover requests at the target eNB and the determination of whether the target eNB can accept an unnecessary handover. Therefore, the processing load of the base station can be reduced, and thus the control delay of the handover can be reduced.

[0314] (2) When it can be determined from the ACB information that the cell cannot be selected as the target cell, the measurement control information of the mobile terminal is adjusted. The measurement control information of the mobile terminals under the umbrella may be adjusted. Among the mobile terminals under the umbrella, the measurement control information of the connected mobile terminals may be adjusted. As a specific example of the adjustment of the measurement control information, removing the cell from the measurement target can be mentioned. This makes it possible to reduce the measurement of a cell that cannot be selected as the target cell due to access restriction. Therefore, power consumption of the mobile terminal can be reduced.

[0315] As specific examples of the method of excluding a cell from the measurement target, the following two cases (1) and (2) are disclosed. (1) When a cell with restricted access is included in the list of measurement target cells (also referred to as Listed cells or Neighboring cells) in the measurement control information disclosed in Non-Patent Document 2, the cell is deleted from the list. (2) A cell with restricted access is included in the blacklist disclosed in Non-Patent Document 2. Cells described in the blacklist are excluded from event evaluation and measurement reporting.

[0316] This modification example is not limited to the application examples described above, and may be used in other application examples. Further, this modification example can be used in combination with Embodiment 1 or Modification Example 1 of Embodiment 1 including other application examples.

[0317] Embodiment 1 Modification Example 3. In Modification Example 3 of Embodiment 1, another solution is disclosed for the same problem as in Modification Example 2 of Embodiment 1. The solution in Modification Example 3 of Embodiment 1 is shown below. In this modification example, the description will focus on the parts different from the solutions in Embodiment 1 and Modification Example 2 of Embodiment 1, and for the parts not described, it is the same as in Embodiment 1 and Modification Example 2 of Embodiment 1.

[0318] The mobile terminal that has received the MTCD restriction information makes a judgment considering the restrictions indicated by the MTCD restriction information. Specifically, the mobile terminal determines whether it is restricted from accessing the cell based on the MTCD restriction information of the cell that is the target of the measurement report. The mobile terminal notifies the serving base station of the judgment result. The serving base station that has received the judgment result performs handover decision processing considering the judgment result of the cell that is the target of the measurement report. The serving base station that has received the judgment result may determine a target cell considering the judgment result of the cell that is the target of the measurement report.

[0319] As specific examples of the determination results, the following three cases (1) to (3) are disclosed. (1) Information on whether or not there are restrictions. It may only notify that there are restrictions. On the contrary, it may only notify that there are no restrictions. (2) Information on whether or not handover is possible. It may only notify that handover is possible. On the contrary, it may only notify that handover is impossible. (3) Information on whether or not it is selectable as a target cell. It may only notify that it is selectable as a target cell. On the contrary, it may only notify that it is not selectable as a target cell.

[0320] When it is determined that there are restrictions, or when it is determined that handover is impossible, or when it is determined that it is not selectable as a target cell, the mobile terminal may not perform a measurement report. In that case, it may only notify the determination result, or it may not notify the determination result either. As a result, radio resources can be effectively utilized.

[0321] As a specific example of a method for the mobile terminal to notify the serving cell of the determination result on whether or not there are restrictions, the "specific example of a method for notifying the serving cell of MTCD restriction information" in Modification Example 2 of Embodiment 1 can be used.

[0322] As a specific example of a determination considering the restrictions indicated by the MTCD restriction information of the mobile terminal that has received the MTCD restriction information, the "specific example of a handover decision process considering the restrictions indicated by the MTCD restriction information of the serving base station that has received the MTCD restriction information" in Modification Example 2 of Embodiment 1 can be used.

[0323] As specific examples of the mobile terminal that notifies the serving base station of the determination result on whether or not its own mobile terminal is restricted with respect to the target cell of the measurement report, the following three cases (1) to (3) are disclosed.

[0324] (1) All mobile terminals.

[0325] (2) Only MTCDs. Normal UEs may not be required to notify. As a result, only the MTCDs restricted by the MTCD restriction information will notify the judgment result. Therefore, the serving base station may determine that a mobile terminal that has not notified the MTCD restriction information is a normal UE and perform handover decision processing on the assumption that it is not restricted by the target cell of the measurement report. This eliminates the need for normal UEs to receive MTCD restriction information, determine whether their own mobile terminals are restricted, and notify the serving base station. Therefore, the processing load on normal UEs can be reduced, and low power consumption of normal UEs can be achieved.

[0326] (3) When the serving base station requests the mobile terminal to notify the judgment result of whether its own mobile terminal is restricted with respect to the target cell of the measurement report, the mobile terminal receives the MTCD restriction information and notifies the judgment result of whether its own mobile terminal is restricted. This eliminates the need for the mobile terminal to send unnecessary notifications when the serving cell does not perform handover decision processing considering the restrictions indicated by the MTCD restriction information. Therefore, a flexible communication system can be constructed. The request for notification of MTCD restriction information may be made by the serving base station using measurement control information. This simplifies the processing of the mobile terminal because the mobile terminal can process the parameters related to measurement simultaneously.

[0327] Next, with reference to FIGS. 20 and 21, a specific example of the sequence of the communication system in Modification 3 of Embodiment 1 will be described. FIGS. 20 and 21 are diagrams showing the sequence of the communication system in Modification 3 of Embodiment 1. FIGS. 20 and 21 are connected at the position of the boundary line BL2. The sequences shown in FIGS. 20 and 21 are similar to the sequences shown in FIGS. 14 and 17 to 19. Therefore, the same step numbers are assigned to the same steps, and the common description is omitted.

[0328] In this operation example, assume that an MTCD with eNB_1 as the serving base station, i.e., the source eNB, is moving closer to HeNB_A. Also assume that the measurement control information for the mobile terminal includes HeNB_A as a measurement target. As a specific example of the restrictions indicated by the MTCD restriction information of HeNB_A, a case where the MTCD cannot be selected as a suitable cell will be disclosed. Also, as a specific example of the cell in which the mobile terminal receives the MTCD restriction information during measurement, the target cell for measurement reporting will be disclosed. Further, as a specific example of the mobile terminal that notifies the serving base station of the determination result as to whether or not the own mobile terminal is subject to restrictions with respect to the target cell for measurement reporting, the case of the MTCD will be disclosed. Also, as a specific example of the method by which the mobile terminal notifies the serving cell of the determination result as to whether or not the own mobile terminal is subject to restrictions with respect to the target cell for measurement reporting, the case of reporting as part of the parameters in the measurement report will be disclosed.

[0329] After the processes of step ST1801 to step ST1803 and step ST1403 are performed as described above, in step ST1901, the mobile terminal determines whether or not the own mobile terminal is an MTCD. For this determination, an MTCD indicator, which is information indicating that it is an MTCD stored in a USIM or the like, may be used. If the mobile terminal determines in step ST1901 that it is an MTCD, it proceeds to step ST1404, and if it determines that it is not an MTCD, it proceeds to step ST1905. By performing the process of step ST1901, in a normal UE, reception of the MTCD restriction information, determination as to whether or not the own mobile terminal is subject to restrictions, and notification to the serving base station can be made unnecessary.

[0330] After the process of step ST1404, in step ST1902, the mobile terminal determines whether or not the target cell for measurement reporting can be selected as a target cell. Specific examples of this determination will be disclosed below.

[0331] Determine based on the MTCD restriction information of the target cell of the measurement report received in step ST1404. If the MTCD restriction information indicates that the MTCD can be selected as a suitable cell, it is determined that the cell can be selected as the target cell. If the MTCD restriction information indicates that the MTCD cannot be selected as a suitable cell, it is determined that the cell cannot be selected as the target cell.

[0332] In step ST1902, if the mobile terminal determines that a cell can be selected as the target cell, it proceeds to step ST1904; if it determines that a cell cannot be selected as the target cell, it proceeds to step ST1903.

[0333] In this operation example, in step ST1404, the mobile terminal receives "MTCD cannot be selected as a suitable cell" as the MTCD restriction information of HeNB_A, which is the target cell of the measurement report. Therefore, in step ST1902, the mobile terminal determines that the cell cannot be selected as the target cell and proceeds to step ST1903.

[0334] In step ST1903, the mobile terminal sets in the measurement report the determination result that there are restrictions for the mobile terminal itself with respect to the target cell of the measurement report.

[0335] In step ST1904, the mobile terminal sets in the measurement report the determination result that there are no restrictions for the mobile terminal itself with respect to the target cell of the measurement report.

[0336] In step ST1905, the mobile terminal notifies eNB_1 of Measurement Reports according to the measurement control information received in step ST1801. The measurement report includes the determination result of whether the mobile terminal is restricted with respect to the cell targeted for the measurement report. In this operation example, the mobile terminal notifies the measurement report of HeNB_A. The measurement report includes the determination result that the mobile terminal has a restriction with respect to HeNB_A.

[0337] In step ST1906, eNB_1, which is the serving base station, performs handover determination processing in consideration of the measurement report received in step ST1905. In this operation example, in step ST1905, eNB_1 has received from the mobile terminal the determination result that the mobile terminal has a restriction with respect to HeNB_A. Based on this determination result, if eNB_1 does not determine to perform a handover with HeNB_A as the target cell, eNB_1 does not execute the processing of step ST1705. By performing the processing of step ST1906, it is possible to reduce the notification of unnecessary handover requests that will surely result in handover rejection because the target eNB restricts the MTCD.

[0338] According to Modification Example 3 of Embodiment 1, in addition to the effects of Modification Example 2 of Embodiment 1, the following effects can be obtained. The serving base station does not need to perform handover determination processing in consideration of the restriction indicated by the MTCD restriction information of the cell targeted for the measurement report. Thereby, the processing load on the serving base station can be reduced.

[0339] This modification example is not limited to the application examples described above, and may be used in other application examples. Further, this modification example can be used in combination with Embodiment 1, Modification Example 1 of Embodiment 1, or Modification Example 2 of Embodiment 1 including other application examples.

[0340] Embodiment 1 Modification Example 4. In Modification Example 4 of Embodiment 1, another solution is disclosed for the same problem as in Modification Example 2 of Embodiment 1. The solution in Modification Example 4 of Embodiment 1 is shown below. In this modification example, the description will focus on the parts that are different from the solutions in Embodiment 1 and Modification Example 2 of Embodiment 1, and for the parts not described, they will be the same as in Embodiment 1 and Modification Example 2 of Embodiment 1.

[0341] The base station notifies the MTCD restriction information of its own cell to neighboring cells. The MTCD restriction information is notified using the X2 interface. The cell that has received the MTCD restriction information and the measurement report from the mobile terminals under its umbrella performs handover decision processing in consideration of the content of the measurement report and the restrictions indicated by the MTCD restriction information of the target cell of the measurement report. Specifically, the target cell is determined in consideration of the content of the measurement report and the restrictions indicated by the MTCD restriction information of the target cell of the measurement report.

[0342] This can reduce the reception of unnecessary handover request notifications that would always result in handover rejection from the cell that has notified the MTCD restriction information of its own cell because the own cell restricts MTCD. By reducing the reception of unnecessary handover request notifications in this way at the base station, unnecessary determination of whether a handover can be accepted can be reduced. As a result, the processing load on the base station can be reduced, and thus the control delay of handover can be reduced.

[0343] As specific examples of the method for determining neighboring cells to which the base station notifies the MTCD restriction information of its own cell, the following four (1) to (4) are disclosed. The cell that notifies the MTCD restriction information of its own cell may be one or a plurality.

[0344] (1) It is determined based on the measurement results of the radio environment around the base station (hereinafter sometimes referred to as the "surrounding radio environment"). Specific examples of the surrounding radio environment include the measurement results of surrounding cells. Specific examples of the measurement results of surrounding cells include received quality, received power, path loss, etc. When the received quality or received power of a cell in the measurement results of the surrounding radio environment is equal to or greater than a predetermined threshold or greater than a predetermined threshold, the base station selects the cell as the cell to notify the MTCD restriction information of its own cell. Alternatively, when the path loss of a cell in the measurement results of the surrounding radio environment is less than or equal to a predetermined threshold, the base station selects the cell as the cell to notify the MTCD restriction information of its own cell. According to this method, when there is a cell with good received quality in the measurement in its own cell, it is simulated that the own cell may be selected as the handover destination of the mobile terminal under the umbrella of the cell with good received quality, and the cell with good received quality is selected as the notification destination of the MTCD restriction information of its own cell.

[0345] (2) It is determined based on the measurement reports from the mobile terminals under the umbrella of the base station. Specific examples of the measurement reports of the mobile terminals include received quality, received power, path loss, etc. When the received quality or received power of a cell in the measurement reports of the mobile terminals is equal to or greater than a predetermined threshold or greater than a predetermined threshold, the base station selects the cell as the cell to notify the MTCD restriction information of its own cell. Alternatively, when the path loss of a cell in the measurement reports of the mobile terminals is less than or equal to a predetermined threshold, the base station selects the cell as the cell to notify the MTCD restriction information of its own cell. In the specific example (1) of the determination method of the surrounding cells, it is determined based on the measurement results at the center of the cell coverage, while in this method, it can be determined based on the measurement results at all points within the cell coverage including the cell edge. Therefore, compared with the specific example (1) of the determination method of the surrounding cells, base stations that may select the own cell as the handover destination can be selected without omission.

[0346] Determine a cell that has been selected as a handover destination (target cell at the time of handover) of a mobile terminal under the coverage of a base station as a neighboring cell to which the MTCD restriction information of its own cell is notified.

[0347] (4) The combination of (1) to (3) above.

[0348] As specific examples of the timing for a base station to notify neighboring cells of the MTCD restriction information of its own cell, the following four cases (1) to (4) are disclosed.

[0349] (1) When the base station is installed. If the MTCD restriction information is statically determined, the number of notifications may be once, so the processing load on the base station can be reduced.

[0350] (2) When the MTCD restriction information is changed. If the MTCD restriction information is not statically determined, it can be reflected each time there is a change. Also, compared with the specific example (3) of the notification timing described later, the number of notifications is reduced, so the processing load on the base station can be reduced.

[0351] (3) Periodically. It is effective in that it is also possible to notify neighboring cells installed after the installation of its own cell or after the change of the MTCD restriction information of its own cell. Also, even if an error occurs during notification, correct information can be notified by notifying periodically.

[0352] (4) The combination of (1) to (3) above.

[0353] As specific examples of the method for notifying MTCD restriction information via the X2 interface, the following three cases (1) to (3) are disclosed.

[0354] (1) New X2 signaling or an X2 message is provided. Control X2 signaling may be provided. Also, X2 signaling that does not require a response message from the receiving base station may be provided. X2 signaling that does not require a response message is also referred to as "Class 2" (see 3GPP TS36.423 V9.4.0 (hereinafter referred to as "Non-Patent Document 12")). Also, X2 signaling that has nothing to do with the mobile terminal may be provided. X2 signaling that has nothing to do with the mobile terminal is also referred to as "non UE associated Signalling" (see Non-Patent Document 12). The parameter mapped to the newly provided X2 signaling is MTCD restriction information. The MTCD restriction information may be notified together with the indicator of the corresponding cell. The cell indicator may be PCI or GCI.

[0355] (2) New X2 signaling or an X2 message is provided. Control X2 signaling may be provided. Also, X2 signaling that requires a response message from the receiving base station may be provided. X2 signaling that requires a response message is also referred to as "Class 1" (see Non-Patent Document 12). Also, X2 signaling that has nothing to do with the mobile terminal may be provided. The parameter mapped to the newly provided X2 signaling is MTCD restriction information. The MTCD restriction information may be notified together with the indicator of the corresponding cell. The cell indicator may be PCI or GCI.

[0356] (3) Existing X2 signaling is used. Existing control X2 signaling may be used. Also, existing X2 signaling that has nothing to do with the mobile terminal may be used. The parameter that needs to be added to the existing X2 signaling is MTCD restriction information. Specific example (3) is effective in that there is no need to provide new signaling compared with specific examples (1) and (2), and it is possible to avoid the complication of the communication system. Next, as specific examples of the existing X2 signaling, the following two of (b1) and (b2) are disclosed.

[0357] (b1) "X2 SETUP REQUEST" (see Non-Patent Document 12). The purpose of "X2 SETUP REQUEST" is for two eNBs to exchange application-level data necessary for correctly sharing the X2 interface. The parameters already included are eNB-specific information such as global cell identifiers, PCI, etc. The MTCD restriction information of the base station is also base station-specific information. Therefore, by using "X2 SETUP REQUEST" to notify the surrounding cells of the MTCD restriction information, the receiving base station can obtain the base station-specific information at once. As a result, the processing load of the base station can be reduced, and the control delay as a communication system can be prevented.

[0358] (b2) "eNB Configuration Update" (see Non-Patent Document 12). The purpose of "eNB Configuration Update" is for two eNBs to update the application-level data necessary for correctly sharing the X2 interface. The parameters already included are eNB-specific information such as the PCI of the eNB. The MTCD restriction information of the base station is also base station-specific information. Therefore, by using "eNB Configuration Update" to notify the surrounding cells of the MTCD restriction information, the receiving base station can obtain the base station-specific information at once. As a result, the processing load of the base station can be reduced, and the control delay as a communication system can be prevented.

[0359] A specific example of the handover decision process of the serving base station that has received the MTCD restriction information, taking into account the restrictions indicated by the MTCD restriction information, is the same as the second modification example of Embodiment 1, so the description is omitted.

[0360] Next, with reference to FIGS. 22 and 23, a specific example of the sequence of the communication system in Modification 4 of Embodiment 1 will be described. FIGS. 22 and 23 are diagrams showing the sequence of the communication system in Modification 4 of Embodiment 1. FIG. 22 and FIG. 23 are connected at the position of the boundary line BL3. Since the sequences shown in FIGS. 22 and 23 are similar to the sequences shown in FIGS. 17 to 19, the same step numbers are assigned to the same steps, and the common description is omitted.

[0361] In this operation example, it is assumed that an MTCD with eNB_1 as the serving base station (source eNB) is moving closer to HeNB_A. It is assumed that HeNB_A has selected eNB_1 as a neighboring cell to which it notifies the MTCD restriction information of its own cell. As a specific example of the timing when the base station notifies the neighboring cell of the MTCD restriction information of its own cell, the case when it is installed is disclosed. As a specific example of the restriction indicated by the MTCD restriction information of HeNB_A, the case where the MTCD cannot be selected as a suitable cell is disclosed.

[0362] The processes of steps ST1801 to ST1803 and step ST1703 are performed as described above. Also, in step ST2001, HeNB_A is installed. In step ST2002, HeNB_A determines a neighboring cell that is the notification destination for notifying the MTCD restriction information of its own cell. In this operation example, it is assumed that HeNB_A has selected eNB_1 as a neighboring cell to which it notifies the MTCD restriction information of its own cell.

[0363] In step ST2003, HeNB_A notifies eNB_1 of the MTCD restriction information. In this operation example, "the MTCD cannot be selected as a suitable cell" is notified as the MTCD restriction information.

[0364] In step ST2004, eNB_1 determines whether the mobile terminal (UE) that notified the measurement report in step ST1703 is an MTCD. For this determination, the MTCD indicator in the UE Context may be used. In step ST2004, if eNB_1 determines that the mobile terminal is an MTCD, it proceeds to step ST2005; if it determines that the mobile terminal is not an MTCD, it proceeds to step ST1704. By performing the process of step ST2004, eNB_1 can perform handover decision processing for the MTCD in a form that distinguishes it from normal UEs according to the restrictions indicated by the MTCD restriction information.

[0365] In step ST2005, eNB_1 determines whether the cell targeted in the measurement report can be selected as the target cell. Specific examples of this determination are disclosed below. eNB_1 makes the determination based on the measurement report received from the mobile terminal (UE) in step ST1703 and the MTCD restriction information of the cells targeted in the measurement reports received from neighboring cells. As a specific example, eNB_1 makes the determination based on the measurement report received from the UE in step ST1703 for the neighboring cell HeNB_A and the MTCD restriction information received from HeNB_A in step ST2003.

[0366] If the MTCD restriction information indicates that the MTCD can be selected as a Suitable Cell, eNB_1 determines in step ST2005 that the cell can be selected as the target cell. If the MTCD restriction information indicates that the MTCD cannot be selected as a Suitable Cell, eNB_1 determines in step ST2005 that the cell cannot be selected as the target cell. If eNB_1 determines that the cell can be selected as the target cell, it proceeds to step ST1704; if it determines that the cell cannot be selected as the target cell, it does not execute the processes of steps ST1704 and ST1705.

[0367] In this operation example, in step ST2003, eNB_1 receives, as the MTCD restriction information of HeNB_A which is the target cell of the measurement report, "MTCD cannot be selected as a suitable cell". Therefore, in step ST2005, eNB_1 determines that it is impossible to select this cell as the target cell, and does not execute the processes of steps ST1704 and ST1705. By performing the process of step ST2005, it is possible to reduce the occurrence of a wasteful handover request notification that will surely result in a handover rejection because the target eNB restricts the MTCD.

[0368] According to Modification Example 4 of Embodiment 1, in addition to the effects of Modification Example 2 of Embodiment 1, the following effects can be obtained. Compared with Modification Example 2 and Modification Example 3 of Embodiment 1, there is no need to add a new function to the mobile terminal. Therefore, the processing load of the mobile terminal can be reduced, and low power consumption can be realized.

[0369] In 3GPP, it is being considered to avoid congestion caused by MTCD on the core network side (see Non-Patent Document 10). In that case, using this modification example, a base station that has obtained the MTCD restriction information of neighboring base stations may control the MTCD restriction information of its own base station. As specific examples of the control, the following three (1) to (3) are disclosed.

[0370] (1) Control to suppress the inflow of MTCD. When a neighboring base station restricts the MTCD, its own cell also restricts the MTCD. When a neighboring base station restricts the MTCD, the MTCD restricted by the neighboring cell is more likely to cause the own cell to perform cell reselection or the like. Therefore, when a neighboring base station restricts the MTCD, by also restricting the MTCD of its own cell, it is possible to prevent in advance the processing load of its own cell from soaring. When a neighboring base station does not restrict the MTCD, perform MTCD restriction according to the processing load and congestion status of its own cell.

[0371] (2) Control to accept the inflow of MTCDs. When a neighboring base station restricts MTCDs and the processing load of its own cell is low (lower than the threshold), the own cell does not restrict MTCDs. This increases the likelihood that MTCDs restricted by neighboring cells will reselect the own cell or the like. Therefore, the service for MTCDs can be continued. The same applies when there is spare radio resources in the own cell (less than the threshold). When a neighboring base station restricts MTCDs and the processing load of its own cell is high (higher than the threshold), MTCD restriction is performed according to the processing load and congestion situation of the own cell. When a neighboring base station does not restrict MTCDs, MTCD restriction is performed according to the processing load and congestion situation of the own cell.

[0372] (3) Adapt to neighboring cells. When a neighboring base station restricts MTCDs, the own cell also restricts MTCDs. Restrict MTCDs in the same way as neighboring cells. When a neighboring base station does not restrict MTCDs, the own cell also does not restrict MTCDs.

[0373] Using this modification example, a base station that has obtained the MTCD restriction information of a neighboring base station may control the MTCD restriction information of its own base station. This modification example may also be used for the access restriction information of the base station instead of the MTCD restriction information. In this case, the base station notifies the neighboring cells of the access restriction information of its own cell. A base station that has obtained the access control information of a neighboring base station performs handover decision processing in consideration of the content of the measurement report received from the mobile terminals under its umbrella and the restrictions indicated by the access restriction information of the target cell of the measurement report. Also, a base station that has obtained the access restriction information of a neighboring base station may control the access restriction of its own base station. A specific example of access restriction information is ACB.

[0374] This modification example is not limited to the application examples described above and may be used in other application examples. Also, this modification example can be used in combination with Embodiment 1, Modification Example 1 of Embodiment 1, Modification Example 2 of Embodiment 1, or Modification Example 3 of Embodiment 1, including other application examples.

[0375] Embodiment 1, Modification 5 In Modification 5 of Embodiment 1, another solution is disclosed for the same problem as in Modification 2 of Embodiment 1. The solution in Modification 5 of Embodiment 1 is shown below. In this modification, the description will focus on the parts that are different from the solutions in Embodiment 1, Modification 2 of Embodiment 1, and Modification 4 of Embodiment 1. For the parts not described, they shall be the same as in Embodiment 1, Modification 2 of Embodiment 1, and Modification 4 of Embodiment 1.

[0376] The base station notifies the MTCD restriction information of its own cell to neighboring cells. The MTCD restriction information may be notified using the S1 interface. The cell that has received the MTCD restriction information from the base station and the measurement report from the mobile terminals under its umbrella performs handover decision processing in consideration of the content of the measurement report and the restrictions indicated by the MTCD restriction information of the target cell of the measurement report. For example, the target cell is determined in consideration of the content of the measurement report and the restrictions indicated by the MTCD restriction information of the target cell of the measurement report.

[0377] This can reduce the receipt of unnecessary handover request notifications from the cell that has notified the MTCD restriction information of its own cell, which would otherwise always result in a handover rejection because the own cell restricts MTCD. By reducing the receipt of such unnecessary handover requests at the base station, unnecessary determination of whether a handover can be accepted can be reduced. Therefore, the processing load of the base station can be reduced, and the control delay of the handover can also be reduced.

[0378] Also, the base station notifies the MTCD restriction information of its own cell to a higher entity. The base station may notify the MTCD restriction information of its own cell to the higher entity using the S1 interface. The higher entity notifies the MTCD restriction information to the base station. The higher entity may notify the MTCD restriction information to the base station using the S1 interface. The MTCD restriction information notified by the higher entity may be information of one or more base stations.

[0379] As specific examples of the upper entity, the following two cases (1) and (2) are disclosed. (1) MME. (2) HeNBGW.

[0380] As a specific example of the timing at which the base station notifies the upper entity of the MTCD restriction information of its own cell, it is the same as the specific example of the timing at which the base station notifies the MTCD restriction information of its own cell to neighboring cells in Modification Example 4 of Embodiment 1.

[0381] As specific examples of the method by which the base station notifies the upper entity of the MTCD restriction information of its own cell using the S1 interface, the following three cases (1) to (3) are disclosed.

[0382] (1) New S1 signaling or an S1 message is provided. Control S1 signaling may be provided. Also, S1 signaling that does not require a response message from the receiving side such as MME, SGSN, etc. may be provided. S1 signaling that does not require a response message is also referred to as "Class 2" (see 3GPP TS36.413 V9.3.0 (hereinafter referred to as "Non-Patent Document 13")). Also, S1 signaling that is irrelevant to the mobile terminal may be provided. S1 signaling that is irrelevant to the mobile terminal is also referred to as "non UE associated Signalling" (see Non-Patent Document 13). The parameter mapped to the newly provided S1 signaling is the MTCD restriction information. The MTCD restriction information may be notified together with the indicator of the corresponding cell. The cell indicator may be PCI or GCI.

[0383] (2) Provide new S1 signaling or an S1 message. It is possible to provide S1 signaling for control purposes. Also, it is possible to provide S1 signaling that requires a response message from the receiving side such as MME or SGSN. The S1 signaling that requires a response message is also referred to as "Class 1" (see Non-Patent Document 13). Also, it is possible to provide S1 signaling that has nothing to do with the mobile terminal. The parameter mapped to the newly provided S1 signaling is MTCD restriction information. The MTCD restriction information may be notified together with the indicator of the corresponding cell. The cell indicator may be PCI or GCI.

[0384] (3) Use existing S1 signaling. It is possible to use existing S1 signaling for control purposes. Also, it is possible to use existing S1 signaling that has nothing to do with the mobile terminal. The parameter that needs to be added to the existing S1 signaling is MTCD restriction information. Specific example (3) is effective in that there is no need to provide new signaling as compared with specific examples (1) and (2), and it is possible to avoid complicating the communication system. Next, as specific examples of the existing S1 signaling, the following two, (a1) and (a2), are disclosed.

[0385] (a1) "S1 SETUP REQUEST" (see Non-Patent Document 13). The purpose of "S1 SETUP REQUEST" is for the eNB and the MME to exchange application-level data necessary for correctly sharing the S1 interface. The parameters already included are information specific to the base station, such as the CSG-ID of the eNB, the global cell identifier, and the TAC. The MTCD restriction information is also information specific to the base station. Therefore, by using "S1 SETUP REQUEST" to notify the MTCD restriction information to the core network side, the receiving-side MME can obtain the information specific to the base station at once. As a result, the processing load on the MME can be reduced, and the control delay of the communication system can be prevented.

[0386] (a2) "eNB Configuration Update" (see Non-Patent Document 13). The purpose of "eNB Configuration Update" is to update the application-level data necessary for the eNB and the MME to correctly share the S1 interface. The parameters already included are base station-specific information such as the CSG-ID and TAC of the eNB. The MTCD restriction information is also base station-specific information. Therefore, by using "eNB Configuration Update" to notify the core network side of the MTCD restriction information, the receiving side, the MME, can obtain the base station-specific information at once. This can reduce the processing load of the MME and prevent the control delay as a communication system.

[0387] As specific examples of the method for determining the cell that notifies the upper entity of the MTCD restriction information of the base station, the following two cases (1) and (2) are disclosed. The cell that notifies the MTCD restriction information of the base station may be one or a plurality. (1) Base stations under the upper entity. (2) Base stations within the same tracking area as the base station that has notified the MTCD restriction information.

[0388] As specific examples of the timing when the upper entity notifies the base station of the MTCD restriction information, the following four cases (1) to (4) are disclosed.

[0389] (1) When the base station is installed. It may also be when the base station is installed under the upper entity. It may also be when the base station is installed within the same tracking area as the base station that has notified the MTCD restriction information. In this method, when the MTCD restriction information is statically determined, the number of notifications may be once, so the processing load of the upper entity can be reduced.

[0390] (2) When the MTCD restriction information is changed. In this method, if the MTCD restriction information is not statically determined, it can be reflected each time there is a change. Also, compared with method (3), the number of notifications is reduced, so the processing load on the base station can be reduced.

[0391] (3) Periodic. In this method, even if an error occurs during notification, correct information can be notified by periodically notifying.

[0392] (4) A combination of the above (1) to (3).

[0393] As specific examples of the method in which the upper entity notifies the base station of the MTCD restriction information using the S1 interface, the following two (1) and (2) are disclosed.

[0394] (1) New S1 signaling or an S1 message is provided. The detailed description is the same as in specific examples (1) and (2) of the method in which the base station notifies the upper entity of the MTCD restriction information of its own cell using the S1 interface.

[0395] (2) Existing S1 signaling is used. It may be possible to use the existing S1 signaling for control. Also, it may be possible to use S1 signaling that has nothing to do with the existing mobile terminals. The parameter that needs to be added to the existing S1 signaling is the MTCD restriction information. Specific example (2) is effective in that there is no need to provide new signaling compared with specific example (1), and it is possible to avoid the complication of the communication system.

[0396] Next, as specific examples of the existing S1 signaling, the following two (a1) and (a2) are disclosed.

[0397] (a1) "S1 SETUP RESPONSE" (see Non-Patent Document 13). The purpose of "S1 SETUP RESPONSE" is for the eNB and the MME to exchange application-level data necessary for correctly sharing the S1 interface. "S1 SETUP RESPONSE" is a response signal to "S1 SETUP REQUEST". The parameters already included are MME-specific information such as PLMN Identity and MME Group ID. The MTCD restriction information of the subordinate base stations is also MME-specific information. Therefore, by using "S1 SETUP RESPONSE" to notify the base station of the MTCD restriction information, the receiving base station can obtain MME-specific information at once. As a result, the processing load on the base station can be reduced, and the control delay as a communication system can be prevented.

[0398] (a2) "MME Configuration Update" (see Non-Patent Document 13). The purpose of "MME Configuration Update" is for the eNB and the MME to update application-level data necessary for correctly sharing the S1 interface. The parameters already included are MME-specific information such as PLMN Identity and MME Group ID. The MTCD restriction information of the subordinate base stations is also MME-specific information. Therefore, by using "MME Configuration Update" to notify the base station of the MTCD restriction information, the receiving base station can obtain MME-specific information at once. As a result, the processing load on the base station can be reduced, and the control delay as a communication system can be prevented.

[0399] Next, with reference to FIGS. 24 and 25, a specific example of the sequence of the communication system in Modification 5 of Embodiment 1 will be described. FIGS. 24 and 25 are diagrams showing the sequence of the communication system in Modification 5 of Embodiment 1. FIG. 24 and FIG. 25 are connected at the position of the boundary line BL4. Since the sequences shown in FIGS. 24 and 25 are similar to the sequences shown in FIGS. 17 to 19, FIGS. 22, and 23, the same step numbers are assigned to the same steps, and the common description is omitted.

[0400] In this operation example, it is assumed that an MTCD with eNB_1 as the serving base station (source eNB) is moving closer to HeNB_A. It is assumed that the upper entity of HeNB_A has selected eNB_1 as the neighboring cell that notifies the MTCD restriction information of HeNB_A. As a specific example of the timing when the base station notifies the upper entity of the MTCD restriction information of its own cell, the case when it is installed is disclosed. As a specific example of the restriction indicated by the MTCD restriction information of HeNB_A, the case where the MTCD cannot be selected as a suitable cell is disclosed. As a specific example of the upper entity, the MME is disclosed. The case of a base station under the umbrella of the MME as the cell to which the MME notifies the MTCD restriction information received from the base station is disclosed. As the timing when the MME notifies the base station of the MTCD restriction information, the case when the base station is installed is disclosed. The case where the upper entity notifies the base station of the MTCD restriction information using "S1 SETUP RESPONSE" is disclosed.

[0401] The processes of steps ST1801 to ST1803 and step ST1703 are performed as described above. Also, in step ST2101, HeNB_A is installed. In step ST2102, HeNB_A notifies the upper entity, i.e., the MME, of the MTCD restriction information. In this operation example, HeNB_A notifies "the MTCD cannot be selected as a suitable cell" as the MTCD restriction information.

[0402] In step ST2103, eNB_1 is installed. In step ST2104, in order for eNB_1 to correctly share the S1 interface with the MME, eNB_1 notifies the upper entity, i.e., the MME, of an S1 setup request (S1 SETUP REQUEST) message.

[0403] In step ST2105, the MME determines the cell to which it will notify the received MTCD restriction information of HeNB_A. In this operation example, the MME notifies the MTCD restriction information of the received HeNB_A to the subordinate base stations. Also, in this operation example, the MME notifies the MTCD restriction information when the base station is installed. Since eNB_1 is installed under the MME, the MME notifies the MTCD restriction information of HeNB_A to eNB_1, that is, determines eNB_1 as the notification destination.

[0404] In step ST2106, the MME notifies eNB_1 of the MTCD restriction information of HeNB_A. The MTCD restriction information of HeNB_A and the MTCD restriction information of other cells may be notified together. In this operation example, the MME uses an S1 setup response (S1 SETUP RESPONSE) message to notify the MTCD restriction information. Specifically, the MME notifies eNB_1 of an S1 setup response message including the MTCD restriction information. In this operation example, the MME notifies "not selectable as a suitable cell for MTCD" as the MTCD restriction information.

[0405] Next, eNB_1 performs the process of step ST2004 as described above. If eNB_1 determines that the mobile terminal (UE) that notified the measurement report in step ST1703 is an MTCD, it proceeds to step ST2107; if it determines that it is not an MTCD, it proceeds to step ST1704.

[0406] In step ST2107, eNB_1 determines whether the cell to be measured can be selected as the target cell. Specific examples of this determination are disclosed below. The determination is made based on the measurement report received in step ST1703 and the MTCD restriction information of the cell to be measured received from the MME. In this operation example, the determination is made based on the measurement report for HeNB_A received in step ST1703 and the MTCD restriction information of HeNB_A received from the MME in step ST2106.

[0407] When the MTCD restriction information indicates that the MTCD can be selected as a suitable cell, eNB_1 determines that the cell can be selected as the target cell. When the MTCD restriction information indicates that the MTCD cannot be selected as a suitable cell, eNB_1 determines that the cell cannot be selected as the target cell. In step ST2107, if eNB_1 determines that a cell can be selected as the target cell, it proceeds to step ST1704; if it determines that the cell cannot be selected as the target cell, it does not execute the processes of steps ST1704 and ST1705. When proceeding to step ST1704, the processes of steps ST1704 to ST1711 are performed as described above.

[0408] In this operation example, in step ST2106, eNB_1 receives, as the MTCD restriction information of HeNB_A, which is the cell to be measured, "MTCD cannot be selected as a suitable cell". Therefore, eNB_1 determines in step ST2107 that the cell cannot be selected as the target cell and does not execute the processes of steps ST1704 and ST1705. By performing the process of step ST2107, it is possible to reduce the occurrence of unnecessary handover request notifications that would always result in handover rejection because the target eNB restricts the MTCD.

[0409] According to Modification Example 5 of Embodiment 1, the same effects as those of Modification Example 4 of Embodiment 1 can be obtained.

[0410] This modification example is not limited to the application examples described above, and may be used in other application examples. For example, in this modification example, in step ST1706, the target eNB, i.e., HeNB_A, determines whether the home base station can accept handover. This is not a limitation. For example, when handover is performed via the MME, the MME may determine whether the target eNB can accept handover in consideration of the MTCD restriction information acquired by the MME from the base station.

[0411] In addition, this modification example can be used in combination with Embodiment 1, Modification Example 1 of Embodiment 1, Modification Example 2 of Embodiment 1, Modification Example 3 of Embodiment 1, or Modification Example 4 of Embodiment 1, including other application examples.

[0412] Embodiment 1 Modification Example 6. In Modification Example 6 of this Embodiment 1, another solution is disclosed for the same problem as in Modification Example 2 of Embodiment 1. The solution in Modification Example 6 of Embodiment 1 is shown below. In this modification example, the description will focus on the parts different from the solutions in Embodiment 1, Modification Example 2 of Embodiment 1, Modification Example 4 of Embodiment 1, and Modification Example 5 of Embodiment 1, and for the parts not described, it shall be the same as in Embodiment 1, Modification Example 2 of Embodiment 1, Modification Example 4 of Embodiment 1, and Embodiment 5.

[0413] The base station notifies the upper entity of the MTCD restriction information of its own cell. The base station may notify the upper entity of the MTCD restriction information of its own cell using the S1 interface. The upper entity sets the mobile terminal context in the serving cell of the mobile terminal in consideration of the received MTCD restriction information. The upper entity may also set the mobile terminal context for the MTCD in the serving cell of the MTCD in consideration of the received MTCD restriction information.

[0414] The cell that receives the mobile terminal context and the measurement report from the mobile terminal under the umbrella performs handover decision processing in consideration of their contents. For example, a target cell is determined in consideration of the mobile terminal context and the measurement report from the mobile terminal under the umbrella.

[0415] By doing so, it is possible to reduce the base station from receiving a wasteful handover request notification from the cell that has notified the MTCD restriction information of its own cell, which will always result in a handover rejection because its own cell is restricting the MTCD. By reducing the reception of such wasteful handover requests by the base station, it is possible to reduce the wasteful determination of whether the base station can accept a handover. Therefore, the processing load of the base station can be reduced, and the control delay of the handover can also be reduced.

[0416] In this modification example, the case where the cell that has received the mobile terminal context and the measurement report from the mobile terminal under the umbrella performs handover decision processing in consideration of their contents has been described. However, the present invention is not limited to this. The cell that has received the mobile terminal context may perform an operation in consideration of the contents of the mobile terminal context.

[0417] In this modification example, the case where the mobile terminal context is set to the serving cell of the mobile terminal in consideration of the MTCD restriction information received by the upper entity has been described. However, the present invention is not limited to this, and the following may also be possible. Among the MTCD restriction information received by the upper entity, the mobile terminal context may be set to the serving cell of the mobile terminal in consideration of the MTCD restriction information of the base station belonging to the same CSG-ID as the mobile terminal. Also, among the MTCD restriction information received by the upper entity, the mobile terminal context may be set to the serving cell of the mobile terminal without considering the MTCD restriction information of the base station not belonging to the same CSG-ID as the mobile terminal. This can reduce the amount of information for control within the communication system.

[0418] The following discloses a specific example of when a higher-level entity sets the mobile terminal context to the serving cell of the mobile terminal in consideration of the received MTCD restriction information. Existing control S1 messages or S1 signaling may be used. A specific example of existing S1 signaling is the "INITIAL CONTEXT SETUP REQUEST" for initial context setup request (see Non-Patent Document 13).

[0419] As specific examples of when a higher-level entity notifies the content of the mobile terminal context to the serving cell in consideration of the received MTCD restriction information, the following two cases (1) and (2) are disclosed.

[0420] (1) A new parameter is provided in the mobile terminal context. As specific examples of the new parameter, the following three cases (a1) to (a3) are disclosed.

[0421] (a1) Map the MTCD restriction information. The MTCD restriction information may be notified together with the indicator of the corresponding cell. The cell indicator may be the PCI or the GCI. The serving cell that received the information may notify the information to the mobile terminal.

[0422] (a2) Map the information that "cannot be selected as a cell reselection destination". The information may be notified together with the indicator of the corresponding cell. The cell indicator may be the PCI or the GCI. The serving cell that received the information may notify the information to the mobile terminal. According to the specific example (a2), the MTCD can know in advance a cell that cannot be reselected due to being restricted by the MTCD before receiving the MTCD restriction information of the cell. Thereby, the power consumption of the MTCD can be reduced, and the control delay of cell reselection can be reduced.

[0423] (a3) Map the information of "cannot be set as the measurement target". This information may be notified together with the indicator of the corresponding cell. The indicator of the cell may be PCI or GCI. The serving cell may adjust the measurement control information of the mobile terminal in consideration of this information. For example, remove the cell that has received the notification of the information of "cannot be set as the measurement target" from the measurement targets in the measurement control information. As a specific example of the method of removing from the measurement targets, the same method as in Modification Example 2 of Embodiment 1 can be cited. Thereby, it is possible to reduce the MTCD from performing measurements on cells that cannot be selected as target cells. Therefore, low power consumption of the MTCD can be realized.

[0424] (2) Use the existing parameters in the "INITIAL CONTEXT SETUP REQUEST". For example, use the "Handover Restriction List IE". The purpose of the "Handover Restriction List IE" is to indicate roaming or access restriction. The points that need to be changed for the existing parameters are disclosed below. In the existing "Handover Restriction List IE", set the area where roaming or handover is prohibited. Specifically, the prohibited tracking area (Forbidden TACs) or the prohibited system (Forbidden inter RATs) is set. Therefore, it is impossible to notify the MTCD restriction information specific to the base station using this parameter "Handover Restriction List IE". Therefore, in this modification example, the information of the forbidden cell (Forbidden Cell) is added. A cell where roaming is prohibited and a cell where handover is prohibited may be provided respectively.

[0425] As specific examples of setting the mobile terminal context considering the MTCD restriction information, six examples of (1) to (6) below are disclosed.

[0426] (1) The restrictions indicated by the MTCD restriction information are whether the MTCD can access or not. When it is shown that access is impossible, the following five specific examples of setting the mobile terminal context are disclosed as (a1) to (a5). (a1) Make it impossible to select as a cell reselection destination. By this, it is possible to prevent in advance the reselection of a cell that becomes inaccessible. (a2) Make it impossible to set as a measurement target. By this, even if selected as a handover destination, it is possible to reduce the measurement for an inaccessible cell. (a3) Set as a cell where handover is prohibited. Make it impossible to select as a target cell. By this, it is possible to prevent in advance the selection of an inaccessible cell as a handover destination. (a4) Set as a cell where roaming is prohibited. By this, it is possible to prevent in advance the selection of an inaccessible cell as a roaming destination. (a5) A combination of the above (a1) to (a4).

[0427] (2) The restrictions indicated by the MTCD restriction information are whether the MTCD can camp on to obtain normal services or not. When it is shown that it is impossible to camp on to obtain normal services, the following five specific examples of setting the mobile terminal context are disclosed as (b1) to (b5). (b1) Make it impossible to select as a cell reselection destination. By this, it is possible to prevent in advance the reselection of a cell where normal services cannot be obtained. (b2) Make it impossible to set as a measurement target. By this, even if selected as a handover destination, it is possible to reduce the measurement for a cell where normal services cannot be obtained. (b3) Set as a cell where handover is prohibited. Make it impossible to select as a target cell. By this, it is possible to prevent in advance the selection of a cell where normal services cannot be obtained as a handover destination. (b4) Set as a cell where roaming is prohibited. By this, it is possible to prevent in advance the selection of a cell where normal services cannot be obtained as a roaming destination. (b5) A combination of the above (b1) to (b4).

[0428] (3) Whether the restriction indicated by the MTCD restriction information allows the MTCD to camp on to obtain limited services. When it is shown that camping on is not possible to obtain limited services, five specific examples of setting the mobile terminal context are disclosed as follows: (c1) Make it impossible to select as a cell reselection destination. This can prevent, in advance, reselection of a cell that cannot provide limited services. (c2) Make it impossible to set as a measurement target. This can reduce measurements for a cell that cannot provide limited services even if selected as a handover destination. (c3) Set as a cell where handover is prohibited. Make it impossible to select as a target cell. This can prevent, in advance, selection of a cell that cannot provide limited services as a handover destination. (c4) Set as a cell where roaming is prohibited. This can prevent, in advance, selection of a cell that cannot provide limited services as a roaming destination. (c5) A combination of the above (c1) to (c4).

[0429] (4) Whether the restriction indicated by the MTCD restriction information prohibits the MTCD from being a candidate for cell selection and reselection. When it is shown that being a candidate for cell selection and reselection is prohibited, five specific examples of setting the mobile terminal context are disclosed as follows: (d1) Make it impossible to select as a cell reselection destination. This can prevent, in advance, reselection of a cell before receiving the MTCD restriction information of the cell. (d2) Make it impossible to set as a measurement target. This can reduce measurements for a cell that cannot be selected as a cell reselection destination even if selected as a handover destination. (d3) Set as a cell where handover is prohibited. Make it impossible to select as a target cell. This can prevent, in advance, selection of a cell that cannot be selected as a cell reselection destination as a handover destination. (d4) Set as a cell where roaming is prohibited. This can prevent, in advance, selection of a cell that cannot be selected as a cell reselection destination as a roaming destination. (d5) A combination of the above (d1) to (d4).

[0430] (5) Whether the restriction indicated by the MTCD restriction information prohibits the MTCD from roaming. When it prohibits roaming, five specific examples of setting the mobile terminal context are disclosed as follows: (e1) It is set to be unselectable as a cell reselection destination. This can prevent, in advance, reselection of a cell that cannot be roamed to. (e2) It is set to be unconfigurable as a measurement target. This can reduce the measurement for a cell that cannot be roamed to, even if it is selected as a handover destination. (e3) It is set as a cell where handover is prohibited. It is set to be unselectable as a target cell. This can prevent, in advance, selection of a cell that cannot be roamed to as a handover destination. (e4) It is set as a cell where roaming is prohibited. (e5) A combination of the above (e1) to (e4).

[0431] (6) Whether the restriction indicated by the MTCD restriction information prohibits the MTCD from performing handover. When it prohibits handover, five specific examples of setting the mobile terminal context are disclosed as follows: (f1) It is set to be unselectable as a cell reselection destination. This can prevent, in advance, reselection of a cell that cannot be handed over to. (f2) It is set to be unconfigurable as a measurement target. This can reduce the measurement for a cell that cannot be handed over to, even if it is selected as a handover destination. (f3) It is set as a cell where handover is prohibited. It is set to be unselectable as a target cell. (f4) It is set as a cell where roaming is prohibited. This can prevent, in advance, selection of a cell that cannot be handed over to as a roaming destination. (f5) A combination of the above (f1) to (f4).

[0432] Among specific examples in which the upper entity notifies the content of the mobile terminal context in consideration of the received MTCD restriction information, when mapping the MTCD restriction information using (a1) of the specific example (1), the base station may consider the content of a specific example of setting the mobile terminal context in consideration of the MTCD restriction information.

[0433] Specific examples of the timing at which the upper entity notifies the mobile terminal context to the serving cell of the mobile terminal are disclosed below. The timing of setting the initial mobile terminal context.

[0434] Next, with reference to FIGS. 26 and 27, a specific example of the sequence of the communication system in Modification Example 6 of Embodiment 1 will be described. FIGS. 26 and 27 are diagrams showing the sequence of the communication system in Modification Example 6 of Embodiment 1. FIGS. 26 and 27 are connected at the position of the boundary line BL5. Since the sequences shown in FIGS. 26 and 27 are similar to the sequences shown in FIGS. 17 to 19 and FIGS. 22 to 25, the same step numbers are assigned to the same steps, and the common description is omitted.

[0435] In this operation example, it is assumed that an MTCD with eNB_1 as the serving base station (source eNB) is moving closer to HeNB_A. As a specific example of the timing at which the base station notifies the upper entity of the MTCD restriction information of its own cell, the case when it is installed is disclosed. As a specific example of the restriction indicated by the MTCD restriction information of HeNB_A, the case where it is shown that camping on is impossible to obtain normal service is disclosed. As a specific example of the upper entity, the MME is disclosed. As a specific example of setting the mobile terminal context by the upper entity in consideration of the MTCD restriction information, the case where it is assumed that it cannot be selected as the target cell when the MTCD restriction information indicates that camping on is impossible to obtain normal service is disclosed.

[0436] As described above, in step ST2101, HeNB_A is installed, and in step ST2102, MTCD restriction information is notified from HeNB_A to the MME, which is the upper entity. In step ST2201, connection processing is started between the UE and the core network side including eNB_1, which is the source eNB, and the MME.

[0437] In step ST2202, the MME determines the content of the mobile terminal context for the UE. The MME determines the content of the mobile terminal context in consideration of the MTCD restriction information received from the subordinate base stations. In this operation example, the MME determines the content of the mobile terminal context in consideration of the MTCD restriction information of HeNB_A received in step ST2102. The MTCD restriction information received from HeNB_A and other base stations may be considered together. In this operation example, the MTCD restriction information of HeNB_A indicates that it is impossible to camp on for obtaining normal services. Also, as the content of the mobile terminal context, it is determined that HeNB_A cannot be selected as the target cell.

[0438] In step ST2203, the MME notifies eNB_1, which is the serving cell of the mobile terminal, of the content of the mobile terminal context determined in step ST2202. Then, the processes of steps ST1801 to ST1803 and step ST1703 are performed as described above.

[0439] In step ST2204, eNB_1 determines whether the target cell of the measurement report can be selected as the target cell. A specific example of this determination is disclosed below. The determination is made based on the measurement report received in step ST1703 and the content of the mobile terminal context received from the MME in step ST2203. In step ST2204, if eNB_1 determines that it can be selected as the target cell, it proceeds to step ST1704, and if it determines that it cannot be selected as the target cell, it does not execute the processes of steps ST1704 and ST1705.

[0440] In this operation example, it is shown that in the context of the mobile terminal, selecting HeNB_A as the target cell is not possible. Therefore, eNB_1 determines that it is not possible to select this cell as the target cell in step ST2204, and does not execute the processes of steps ST1704 and ST1705. By performing the process of step ST2204, it is possible to reduce the notification of unnecessary handover requests that will surely result in a handover rejection because the target eNB restricts the MTCD.

[0441] According to Modification Example 6 of Embodiment 1, the same effects as those of Modification Example 4 of Embodiment 1 can be obtained.

[0442] Also, as disclosed in Embodiment 1, the MTCD restriction information can be used even when congestion occurs in the radio section by the MTCD or on the core network side. In that case, the following problems occur. The congestion in the radio section by the MTCD or on the core network side changes over time. Therefore, it is also conceivable that the MTCD restriction information of a certain cell changes during the connection of the mobile terminal.

[0443] Therefore, in this Modification Example 6, as a specific example of the timing at which the upper entity notifies the mobile terminal context to the serving cell of the mobile terminal, the timing of setting the initial mobile terminal context is disclosed.

[0444] However, after the initial mobile terminal context is set, when the MTCD restriction information of a certain cell changes in the direction of restricting the MTCD and this cell is selected as the target eNB, a problem occurs in that it is not possible to reduce the notification of unnecessary handover requests that will surely result in a handover rejection because this cell restricts the MTCD.

[0445] A solution is disclosed below. As a specific example of notifying the serving cell of the content of the mobile terminal context in consideration of the MTCD restriction information received by the upper entity, the following content is added to the content disclosed in Modification Example 6 of Embodiment 1. The content of the specific example disclosed in Modification Example 6 of Embodiment 1 is newly added to the modification (CONTEXT MODIFICATION) of the mobile terminal context disclosed in Non-Patent Document 13. A "Handover Restriction List IE" is newly added to the existing "CONTEXT MODIFICATION". As a result, even when the MTCD restriction information of a certain cell changes in the direction of restricting the MTCD after the initial mobile terminal context is set, it becomes possible to notify the serving cell of the information. Therefore, it is possible to reduce the notification of unnecessary handover requests that always result in handover rejection because the cell restricts the MTCD.

[0446] This modification example is not limited to the application examples described above, and may be used in other application examples. Also, this modification example can be used in combination with Embodiment 1, Modification Example 1 of Embodiment 1, Modification Example 2 of Embodiment 1, Modification Example 3 of Embodiment 1, Modification Example 4 of Embodiment 1, Modification Example 5 of Embodiment 1, including other application examples.

[0447] Embodiment 2. In this Embodiment 2, another solution is disclosed for the same problem as in the aforementioned Embodiment 1. The solution in Embodiment 2 is shown below. The MTCD restricts the selection of the HeNB as the connection destination. The restriction may be static or predetermined. A mobile terminal that is not an MTCD, that is, a normal UE, does not restrict the selection of the HeNB as the connection destination. The normal UE may operate as usual. As a result, the problem that the HeNB cannot accommodate normal UEs because the number of accommodated MTCDs reaches the maximum number of accommodable ones can be solved.

[0448] The mobile terminal determines whether to select a HeNB as a connection destination based on information for determining whether the base station is a HeNB. The information for the mobile terminal to determine whether the base station is a HeNB is information regarding the base station whose selection as a connection destination by the MTCD is restricted, corresponding to the base station information. As specific examples of the information for the mobile terminal to determine whether the base station is a HeNB, the following two cases (1) and (2) are disclosed.

[0449] (1) Use existing notification information related to the HeNB (see Non-Patent Document 2). As a specific example, there is SIB9, and more specifically, "hnb-name" in SIB9. As a specific example of the determination, if the notification information contains notification information related to the HeNB, the base station is determined to be a HeNB. If the notification information does not contain notification information related to the HeNB, the base station is determined not to be a HeNB. This specific example (1) has the advantage that it can avoid complicating the communication system in that it does not require a new indicator as compared with the following specific example (2).

[0450] (2) A new indicator for whether it is a HeNB is provided. The indicator may indicate that it is a HeNB or that it is not a HeNB. As a specific example of the determination, when it is notified that it is a HeNB, the base station is determined to be a HeNB. When it is notified that it is not a HeNB, the base station is determined not to be a HeNB. As specific examples of the notification method of the indicator, the following three cases (a1) to (a3) are disclosed. (a1) It is notified as notification information. By this, the mobile terminal can receive the indicator for whether it is a HeNB regardless of the state of the mobile terminal, that is, regardless of whether the mobile terminal is in the standby state or the connected state. (a2) A region where only the MTCD decodes is provided, and the indicator for whether it is a HeNB is mapped to that region. By this, a normal UE does not need to receive and decode the region. Therefore, no change to the existing 3GPP devices is required, and a communication system excellent in backward compatibility can be constructed. It may be a region related only to the MTCD. (a3) A combination of the above (a1) and (a2).

[0451] As specific examples of the cell in which the mobile terminal receives information for determining whether it is a HeNB, the following two cases (1) and (2) are disclosed. (1) The cell in which measurement is performed. (2) The cell that satisfies the cell selection criteria. In the specific example (2), compared with the specific example (1), the number of cells that need to receive information for determining whether it is a HeNB is reduced. Therefore, by using the specific example (2), the processing load of the mobile terminal can be reduced, and low power consumption of the mobile terminal can be realized.

[0452] As specific examples of the timing when the MTCD determines whether the base station is a HeNB, the following five cases (1) to (5) are disclosed. The specific examples disclosed below may be the timing when the mobile terminal checks the MTCD restriction information.

[0453] (1) When selecting a cell. In this case, the MTCD checks the information for determining whether it is a HeNB before cell selection, and checks whether the cell can be selected (camped on). If the cell is not a HeNB, the cell is selected. If the cell is a HeNB, the cell is removed from the cell selection candidates, and the operation is started to select another cell.

[0454] (2) When reselecting a cell. In this case, the MTCD checks the information for determining whether it is a HeNB before cell reselection, and checks whether the cell can be reselected (camped on). If the cell is not a HeNB, the cell is reselected. If the cell is a HeNB, the cell is removed from the cell reselection candidates, and the operation is started to reselect another cell.

[0455] (3) When accessing. In this case, the MTCD checks the information for determining whether it is a HeNB before access, and checks whether the cell is accessible. If the cell is not a HeNB, access is started by the cell. If the cell is a HeNB, access is aborted, or the cell reselection operation is started to select another accessible cell.

[0456] (4) Periodic. In this case, the MTCD receives and checks the information for determining whether it is a HeNB at a predetermined period.

[0457] (5) Combinations of (1) to (4) above.

[0458] The MTCD may check the information for determining whether it is a HeNB. A normal UE does not have to check the information for determining whether it is a HeNB. Thus, it is not necessary to change to a normal UE, and a communication system excellent in backward compatibility can be constructed.

[0459] As specific examples of the restrictions when the MTCD restricts the selection of a HeNB, seven of the following (1) to (7) are disclosed.

[0460] (1) The MTCD does not access the HeNB. Five specific examples of access are disclosed as follows: (a1) Uplink control data transmission. (a2) Uplink traffic data transmission, which may be the transmission of user data. (a3) RACH transmission. (a4) Transmission of an RRC connection request. (a5) A combination of (a1) to (a4) above.

[0461] (2) The MTCD does not camp on the HeNB to obtain normal services. In other words, the MTCD does not select the HeNB as a suitable cell.

[0462] (3) The MTCD does not camp on the HeNB to obtain limited services. In other words, the MTCD does not select the HeNB as an acceptable cell. Four specific examples of limited services are disclosed as follows: (b1) Initiation of an emergency call. (b2) Reception of ETWS. (b3) Reception of CMAS. (b4) A combination of (b1) to (b3) above.

[0463] (4) The MTCD excludes the HeNB from the candidates for cell selection and reselection. The MTCD does not perform cell selection and reselection on the HeNB.

[0464] (5) The MTCD excludes the HeNB from the candidates for roaming destinations. The MTCD does not select the HeNB as a roaming destination.

[0465] (6) The MTCD excludes the HeNB from the candidates for handover destinations. The MTCD does not select the HeNB as a handover destination. (7) A combination of (1) to (6) above.

[0466] When the MTCD restricts the selection of the HeNB, as a restriction, the above specific examples (1) to (7) may be combined such that one operation is restricted while one operation is not restricted. As specific examples of the combinations of the above specific examples (1) to (7), the following nine (B1) to (B9) are disclosed.

[0467] (B1) The MTCD does not access the HeNB, but the MTCD camps on the HeNB to obtain normal services.

[0468] (B2) The MTCD does not access the HeNB, but the MTCD camps on the HeNB to obtain limited services.

[0469] (B3) The MTCD does not access the HeNB, but the MTCD sets the HeNB as a candidate for cell selection and reselection.

[0470] (B4) The MTCD does not access the HeNB, but the MTCD selects the HeNB as a roaming destination.

[0471] (B5) The MTCD does not access the HeNB, but the MTCD selects the HeNB as a handover destination.

[0472] (B6) The MTCD does not camp on the HeNB to obtain normal services, but the MTCD camps on the HeNB to obtain limited services.

[0473] (B7) The MTCD does not camp on the HeNB to obtain normal services, but the MTCD sets the HeNB as a candidate for cell selection and reselection.

[0474] (B8) The MTCD does not camp on the HeNB to obtain normal services, but the MTCD selects the HeNB as a roaming destination.

[0475] (B9) The MTCD does not camp on the HeNB to obtain normal service, but the MTCD selects the HeNB as a handover target.

[0476] When restricting the MTCD from selecting the HeNB, there may be no restriction stricter than the restricted operation. In other words, if there is an operation that the MTCD makes impossible for the HeNB, a restriction stricter than the impossible operation may be made operable.

[0477] Among the specific examples of the restrictions when the aforementioned MTCD restricts selecting the HeNB, among specific examples (1) to (4), the restriction in specific example (1) is the loosest restriction, and the larger the number of the specific example, the stricter the restriction. For convenience, it will be described excluding specific examples (5), (6), and (7).

[0478] For example, when the restriction of "the MTCD does not access the HeNB" in specific example (1) is imposed, a restriction stricter than this restriction is considered not to be imposed. Therefore, the MTCD camps on the HeNB to obtain normal service, camps on the HeNB to obtain limited service, and the HeNB will be a candidate for cell selection and reselection.

[0479] It is not necessary to restrict the "MTCD" from selecting the HeNB. As specific examples, the following three of (1) to (3) are disclosed.

[0480] (1) Perform restricted operations according to the priority of the MTCD. This is effective when there is a distinction between a high-priority MTCD and a low-priority MTCD in a communication system. As specific examples of combinations with restrictions, the following two of (a1) and (a2) are disclosed. (a1) A low-priority MTCD is restricted from selecting the HeNB. (a2) Separate restrictions on selecting the HeNB are provided for high-priority MTCDs and low-priority MTCDs. For example, a high-priority MTCD is assumed not to access the HeNB, and a low-priority MTCD is assumed not to perform cell selection and reselection of the HeNB.

[0481] (2) Perform restricted operations according to the MTCD group. This is effective when an MTCD group is provided in the communication system. Specific examples are shown below. For example, assume there are MTCD group A and MTCD group B. Separate restrictions are provided for selecting HeNB for each MTCD group, that is, for MTCD group A and for MTCD group B. For example, assume that MTCD group A is not allowed to access the HeNB, and MTCD group B is not allowed to perform cell selection and reselection of the HeNB.

[0482] (3) Perform restricted operations according to the priority of the mobile terminal. This is effective when there is a distinction between high-priority mobile terminals and low-priority mobile terminals, rather than a distinction between whether it is an MTCD or not, in the communication system. As specific examples, the following two cases (b1) and (b2) are disclosed. (b1) Low-priority mobile terminals are restricted from selecting the HeNB. (b2) Separate restrictions are provided for selecting the HeNB for high-priority mobile terminals and low-priority mobile terminals. For example, assume that high-priority mobile terminals are not restricted from selecting the HeNB, and low-priority MTCDs are not allowed to perform cell selection and reselection of the HeNB.

[0483] The restrictions may be changed according to the state of the HeNB. For example, the restrictions on selecting the HeNB by the MTCD may be changed according to the state of the HeNB. As a specific example, for a service-providing HeNB installed within the coverage area of another cell, the MTCD is restricted from selecting the HeNB. Specific examples of the method by which the mobile terminal determines that the HeNB is installed within the coverage area of another cell are disclosed below. When there is a base station that meets the cell selection criteria in addition to the HeNB, it is determined that the HeNB is installed within the coverage area of another cell.

[0484] For an area-complementary HeNB, which is a HeNB installed outside the coverage area of other cells, the MTCD is not restricted from selecting the HeNB, or the restriction is looser than that for a service-providing HeNB, which is a HeNB installed within the coverage area of other cells. Specific examples of methods for a mobile terminal to determine that the HeNB is installed outside the coverage area of other cells are disclosed below. If there is no base station that meets the cell selection criteria other than the HeNB, it is determined that the HeNB is installed outside the coverage area of other cells.

[0485] Accordingly, for an area-complementary HeNB through which the mobile communication system service can be received only, the MTCD is not restricted from selecting the HeNB. Therefore, the service for the MTCD in such a situation can be continued. Also, for a service-providing HeNB through which the mobile communication system service can be received via other cells, the MTCD is restricted from selecting the HeNB. Therefore, the problem that the accommodation number reaches the allowable number due to the MTCD and the normal UEs cannot be accommodated can be solved.

[0486] When changing the restriction according to the state of the HeNB, the change in the state of the HeNB may trigger cell reselection of the MTCDs under the HeNB. Examples of the case where the state of the HeNB is changed include, for example, when other cells are installed around the HeNB that was installed outside the coverage area of other cells, and the state of the HeNB becomes one installed within the coverage area of other cells. In this case, for example, the MTCD changes from a state where it is not restricted from selecting the HeNB to a state where it is restricted from selecting the HeNB. Therefore, as described above, the change in the state of the HeNB triggers cell reselection of the MTCDs under the HeNB. Therefore, the MTCDs under the HeNB may start a cell reselection operation to select other cells where they can camp to obtain normal services.

[0487] Next, with reference to FIG. 28, a specific example of the sequence of the communication system in Embodiment 2 will be described. FIG. 28 is a diagram showing the sequence of the communication system in Embodiment 2. Since the sequence shown in FIG. 28 is similar to the sequence shown in FIG. 14, the same step numbers are assigned to the same steps, and the common description is omitted.

[0488] In this operation example, a case where the mobile terminal uses the existing notification information "hnb-name" as a specific example of the information for determining whether the base station is a HeNB will be disclosed. Also, a case where the cell in which the mobile terminal receives the information for determining whether the base station is a HeNB satisfies the cell selection criteria will be disclosed. Also, as a specific example of the timing for the mobile terminal to determine whether the base station is a HeNB, the time of cell selection will be disclosed. As a specific example of the restriction when restricting the MTCD from selecting a HeNB, a case where the MTCD does not select a HeNB as a suitable cell will be disclosed. Assume that a mobile terminal (UE) exists within the coverage of HeNB_A and is performing a cell selection operation.

[0489] The processes of step ST1401 and step ST1402 are performed as described above. In step ST2301, HeNB_A notifies the mobile terminals under its umbrella of the "hnb-name", which is the information for determining whether the base station of HeNB_A is a HeNB, as notification information by SIB9.

[0490] In step ST2302, the UE receives the information for determining whether the base station is a HeNB. Specifically, the UE receives the information for determining whether the base station that is determined to satisfy the cell selection criteria in step ST1402 is a HeNB. In this operation example, the UE receives the "hnb-name", which is the information for determining whether the base station of HeNB_A is a HeNB.

[0491] In step ST2303, the UE determines whether the self - moving terminal is an MTCD. For this determination, information indicating that it is an MTCD (MTCD indicator) stored in a USIM or the like may be used. If the UE determines in step ST2303 that it is an MTCD, it proceeds to step ST2304; if it determines that it is not an MTCD, it proceeds to step ST1407. By performing the process of step ST2303, the UE can restrict the operation of the MTCD in a form that differentiates it from a normal UE.

[0492] In step ST2304, the UE determines whether the cell is a HeNB. For this determination, the information for determining whether it is a HeNB received in step ST2301 is used. In this operation example, as the information for determining whether it is a HeNB, among the notification information, the HeNB - related notification information is used. As the information for determining whether it is a HeNB, "hnb - name" in the notification information may also be used. If the UE determines in step ST2304 that it is not a HeNB, it proceeds to step ST1407; if it determines that it is a HeNB, it returns to step ST1401.

[0493] In this operation example, HeNB_A is the HeNB that notifies "hnb - name" in step ST2301. Therefore, the UE determines in step ST2304 that it is a HeNB, and without performing cell selection in step ST1407, returns to step ST1401. By performing the process of step ST2304, the operation of the MTCD can be restricted.

[0494] According to Embodiment 2, the following effects can be obtained. It becomes possible to restrict the MTCD from selecting a HeNB in a form that differentiates it from a normal UE. Thereby, the problem that the number of accommodated HeNBs reaches the number that can be accommodated by the MTCD, the HeNB is occupied by the MTCD, and the normal UE cannot be accommodated can be solved. Therefore, the provision of services to the normal UE by the HeNB can be maintained.

[0495] Also, in Embodiment 2, different from Embodiment 1, MTCD restriction information, which is a new indicator notified from the base station to the mobile terminals under its umbrella, becomes unnecessary. As a result, it is possible to avoid the complication of the communication system and also effectively utilize radio resources.

[0496] For so-called local nodes such as HNB, pico eNB (LTE pico cell (EUTRAN pico cell)), pico NB (WCDMA pico cell (UTRAN pico cell)), relay, remote radio head (RRH), and nodes for hot zone cells, etc., the coverage is small, and the number of mobile terminals that can be accommodated is expected to be much smaller compared to the number of mobile terminals that can be accommodated in a macro cell. Therefore, similar to the HeNB, it is considered that the problems of Embodiment 1 occur. To solve this problem, it is also effective to use this embodiment for local nodes such as HNB, pico eNB, pico NB, relay, remote radio head, and nodes for hot zone cells. This can prevent normal UEs from becoming unable to be accommodated due to MTCD, ensure a margin for accommodating normal UEs, and maintain services for normal UEs.

[0497] Also, for macro cells such as eNB and NB, there may be cases where it is desired to prioritize the handling of normal UEs compared to MTCD. For example, it is a case where an event is held within the coverage and the use of a large number of normal UEs is expected. In such a case, it is effective to use this embodiment to solve the problems for macro cells and the like.

[0498] Embodiment 2 is not limited to the application examples described above and may be used in other application examples. Also, Embodiment 2 can be used in combination with Embodiment 1, Modification Example 1 of Embodiment 1, Modification Example 2 of Embodiment 1, Modification Example 3 of Embodiment 1, Modification Example 4 of Embodiment 1, Modification Example 5 of Embodiment 1, or Modification Example 6 of Embodiment 1, including other application examples.

[0499] Embodiment 2, Variation 1 The problem to be solved in Variation 1 of Embodiment 2 will be described below. When the aforementioned Embodiment 2 is used, the following problems occur. For example, consider the case of using Embodiment 2 in a privately-owned HeNB. A privately-owned MTCD that is the same as the HeNB has a problem that its operation to the HeNB is restricted.

[0500] The solution in Variation 1 of Embodiment 2 is shown below. In this variation, the description will focus on the parts different from the solution in Embodiment 2, and for the parts not described, it is the same as in Embodiment 2. Register the MTCD that does not want to be restricted with the same CSG-ID as the base station that does not want to be restricted. The MTCD is restricted from selecting a HeNB that is not registered in the same CSG. This restriction may be static or determined in advance. Mobile terminals other than the MTCD that is not registered in the same CSG as the HeNB, that is, normal UEs, and the MTCD that is registered in the same CSG as the HeNB are not restricted from selecting the HeNB. The normal UEs and the MTCDs registered in the same CSG as the HeNB may operate as normal.

[0501] Therefore, in this variation, the information for the mobile terminal to determine whether the base station is a HeNB indicates restricting the selection of a base station that is not registered in the same group as the MTCD, that is, a HeNB that is not registered in the same CSG as the MTCD.

[0502] As specific examples of the restrictions when an MTCD that is not registered in the same CSG as the HeNB is restricted from selecting the HeNB, the following seven (1) to (7) are disclosed.

[0503] (1) The MTCD does not access an HeNB that is not registered in the same CSG. Five specific examples of access are disclosed below as (a1) to (a5). (a1) Uplink control data transmission. (a2) Uplink traffic data transmission. This may be the transmission of user data. (a3) RACH transmission. (a4) Transmission of an RRC connection request. (a5) A combination of (a1) to (a4) above.

[0504] (2) The MTCD does not camp on an HeNB that is not registered in the same CSG in order to obtain normal services. In other words, the MTCD does not select an HeNB that is not registered in the same CSG as a suitable cell.

[0505] (3) The MTCD does not camp on an HeNB that is not registered in the same CSG in order to obtain limited services. In other words, the MTCD does not select an HeNB that is not registered in the same CSG as an acceptable cell. Four specific examples of limited services are disclosed below as (b1) to (b4). (b1) Making an emergency call. (b2) Receiving an ETWS. (b3) Receiving a CMAS. (b4) A combination of (b1) to (b3) above.

[0506] (4) The MTCD excludes an HeNB that is not registered in the same CSG from the candidates for cell selection and reselection. The MTCD does not perform cell selection and reselection on an HeNB that is not registered in the same CSG.

[0507] (5) The MTCD excludes an HeNB that is not registered in the same CSG from the candidates for roaming destinations. The MTCD does not select an HeNB that is not registered in the same CSG as a roaming destination.

[0508] (6) The MTCD excludes an HeNB that is not registered in the same CSG from the candidates for handover destinations. The MTCD does not select an HeNB that is not registered in the same CSG as a handover destination.

[0509] (7) A combination of (1) to (6) above.

[0510] Next, with reference to FIG. 29, a specific example of the sequence of the communication system in Modification 1 of Embodiment 2 will be described. FIG. 29 is a diagram showing the sequence of the communication system in Modification 1 of Embodiment 2. Since the sequence shown in FIG. 29 is similar to the sequences shown in FIGS. 14 and 28, the same step numbers are assigned to the same steps, and the common description is omitted.

[0511] In this operation example, a case where the mobile terminal uses the existing notification information "hnb-name" as a specific example of information for determining whether the base station is a HeNB will be disclosed. Also, a case where the cell in which the mobile terminal receives information for determining whether the base station is a HeNB satisfies the cell selection criteria will be disclosed. Further, as a specific example of the timing at which the mobile terminal determines whether the base station is a HeNB, the time of cell selection will be disclosed. As a specific example of the limitation when restricting the MTCD from selecting a HeNB, a case where the MTCD does not select a HeNB as a suitable cell will be disclosed. Assume that a mobile terminal (UE) exists within the coverage of HeNB_A and is performing a cell selection operation. The mobile terminal is assumed to be an MTCD and not registered in the same CSG as HeNB_A.

[0512] The processes of step ST1401, step ST1402, and step ST2301 are performed as described above. In step ST2401, HeNB_A notifies the "CSG-ID" as notification information to the mobile terminals under its umbrella (see Non-Patent Document 2). Next, the processes of step ST2302 and step ST2303 are performed as described above.

[0513] In step ST2402, the UE determines whether the mobile terminal is registered in the same CSG as the cell. This determination uses the "CSG-ID" of the cell received in step ST2401. In step ST2402, if the UE determines that it is registered in the same CSG, it proceeds to step ST1407; if it determines that it is not registered in the same CSG, it proceeds to step ST2304. By performing the process of step ST2402, MTCDs that do not want to be restricted by the HeNB, that is, MTCDs registered in the CSG of the HeNB, can be prevented from restricting the selection of the HeNB.

[0514] In this modification example, step ST2304 is provided after step ST2402, but the order of step ST2402 and step ST2304 is arbitrary, and step ST2304 may be provided before step ST2402.

[0515] According to Modification Example 1 of Embodiment 2, in addition to the effects of Embodiment 2, the following effects can be obtained. It becomes possible to restrict an MTCD not registered in the same CSG as the HeNB from selecting the HeNB in a form that distinguishes it from a normal UE and an MTCD registered in the same CSG as the HeNB. As a result, it is possible to prevent the number of accommodated devices of the HeNB from reaching the number of devices that can be accommodated by MTCDs not registered in the same CSG as the home base station, and to solve the problem that it becomes impossible to accommodate a normal UE or an MTCD registered in the same CSG as the home base station. Therefore, it is possible to maintain the provision of services by the HeNB to an MTCD registered in the same CSG as the HeNB and a normal UE.

[0516] This modification example is not limited to the application examples described above, and may be used in other application examples. Further, this modification example can be used in combination with Embodiment 1, Modification Example 1 of Embodiment 1, Modification Example 2 of Embodiment 1, Modification Example 3 of Embodiment 1, Modification Example 4 of Embodiment 1, Modification Example 5 of Embodiment 1, Modification Example 6 of Embodiment 1, or Embodiment 2, including other application examples.

[0517] Embodiment 2, Modification 2 The problem to be solved in Modification 2 of Embodiment 2 will be described below. When Embodiment 2 is used, the following problems occur. Consider the case where the mobile terminal in the connected state is the MTCD. Assume that a HeNB exists around the serving base station of the MTCD. For example, consider the case where the MTCD restricts the HeNB from being a handover destination candidate. In the handover method shown in FIG. 17 described above, the serving base station does not perform handover determination processing according to the selection restriction of the HeNB of the MTCD. Therefore, the serving base station (hereinafter sometimes referred to as "serving cell") performs handover determination processing with the HeNB as the target eNB if conditions other than the selection restriction of the HeNB of the MTCD are met. In that case, as shown in step ST1711 of FIG. 17 described above, mobility control information with the HeNB as the target cell is notified from the serving base station to the MTCD.

[0518] Although the MTCD restricts the HeNB from being a handover destination candidate, it will be notified of an instruction contrary to that restriction from the serving cell. The MTCD cannot determine whether the HeNB should be excluded from the handover destination candidates or should be treated as the target cell that is the handover destination. Thus, a problem occurs in that the communication system becomes unstable.

[0519] The solutions in Modification Example 2 of Embodiment 2 are shown below. In this modification example, the description will focus on the parts different from the solutions in Embodiment 2, and for the parts not described, they shall be the same as those in Embodiment 2. The mobile terminal notifies the serving base station of the information for determining whether the target cell of the measurement report is a HeNB. The mobile terminal may notify the serving base station of the information as to whether the target cell of the measurement report is a HeNB. The serving base station that has received the information for determining whether it is a HeNB performs handover decision processing in consideration of the information for determining whether the target cell of the measurement report is a HeNB. The serving base station that has received the MTCD restriction information may determine the target cell in consideration of the information for determining whether the target cell of the measurement report is a HeNB.

[0520] Also, the serving base station that has received the information for determining whether it is a HeNB may perform handover decision processing for the MTCD in consideration of the information for determining whether the target cell of the measurement report is a HeNB. The serving base station that has received the information for determining whether it is a HeNB may determine the target cell for the MTCD in consideration of the information for determining whether the target cell of the measurement report is a HeNB.

[0521] By doing so, the serving base station will perform handover decision processing for the MTCD with selection restrictions on the HeNB in consideration of the information for determining whether it is a HeNB. And for the normal UE, the serving base station may perform handover decision processing without considering the information for determining whether it is a HeNB on the assumption that it is not affected by the information for determining whether it is a HeNB. Thereby, the processing load of the serving base station for the normal UE can be reduced. A specific example of the method by which the serving base station determines whether the mobile terminal is an MTCD is the same as that in Modification Example 2 of Embodiment 1, so the description thereof is omitted.

[0522] When the mobile terminal makes a measurement, the following two specific examples of cells for receiving information for determining whether it is a HeNB are disclosed: (1) The cell where the measurement is performed. (2) The target cell of the measurement report. In the specific example (2), compared with the specific example (1), the number of cells that need to receive information for determining whether it is a HeNB is reduced. Therefore, the processing load of the mobile terminal can be reduced, and low power consumption of the mobile terminal can be achieved.

[0523] As specific examples of the mobile terminal for notifying the serving base station of information for determining whether the target cell of the measurement report is a HeNB, the following three (1) to (3) are disclosed.

[0524] (1) All mobile terminals.

[0525] (2) MTCD only. Normal UEs may not need to notify. As a result, only the MTCDs that restrict the selection of HeNBs will notify the information for determining whether it is a HeNB. Therefore, the serving base station can determine that the mobile terminals that have not notified the information for determining whether it is a HeNB are normal UEs and do not need to restrict the selection of the target cell of the measurement report, and can perform the handover decision process. As a result, normal UEs do not need to receive the information for determining whether it is a HeNB and notify the serving base station. Therefore, the processing load of normal UEs can be reduced, and low power consumption of the mobile terminal can be achieved.

[0526] (3) When the mobile terminal requests notification of information for determining whether the serving base station is the HeNB of the target cell of the measurement report, it receives and notifies the information for determining whether it is the HeNB. As a result, the mobile terminal does not need to issue unnecessary notifications, such as when it does not perform handover decision processing considering information for determining whether the serving cell is the HeNB. Therefore, it becomes possible to construct a flexible communication system. The request for notification of information for determining whether it is the HeNB may be made by the serving base station based on measurement control information. As a result, since the mobile terminal can simultaneously process parameters related to measurement, the processing of the mobile terminal can be simplified.

[0527] A specific example of the method for notifying the serving cell of the information for determining whether it is the HeNB is the same as the specific example of the method for the mobile terminal to notify the serving cell of the MTCD restriction information in Modification Example 2 of Embodiment 1, and thus the description is omitted.

[0528] A specific example of the information for determining whether it is the HeNB and a specific example of the determination based on the information are the same as those in Embodiment 2, and thus the description is omitted.

[0529] The following discloses a specific example of handover decision processing that takes into account information for determining whether a serving base station has received information for determining whether it is a HeNB. When a mobile terminal in a connected state is an MTCD and it is determined based on the information for determining whether it is a HeNB that the measurement target cell is a HeNB, it is determined that handover with the cell as the target cell is impossible. It may be determined that selection of the cell as the target cell is impossible. When a mobile terminal in a connected state is an MTCD and it is determined based on the information for determining whether it is a HeNB that the measurement target cell is not a HeNB, it is determined that handover with the cell as the target cell is possible. It may be determined that selection of the cell as the target cell is possible. When a mobile terminal in a connected state is a mobile terminal other than an MTCD, it is determined that handover with the cell as the target cell is possible. It may be determined that selection of the cell as the target cell is possible.

[0530] Next, with reference to FIGS. 30 and 31, a specific example of the sequence of the communication system in Modification 2 of Embodiment 2 will be described. FIGS. 30 and 31 are diagrams showing the sequence of the communication system in Modification 2 of Embodiment 2. Since the sequences shown in FIGS. 30 and 31 are similar to the sequences shown in FIGS. 17, 18, 19, and 28, the same step numbers are assigned to the same steps, and common descriptions are omitted.

[0531] In this operation example, assume that an MTCD with eNB_1 as the serving base station (source eNB) is moving closer to HeNB_A. Also assume that the measurement control information for the mobile terminal includes HeNB_A as a measurement target. In this operation example, a case where the mobile terminal uses the existing notification information "hnb - name" as a specific example of the information for determining whether the base station is a HeNB will be disclosed. Also, as a specific example of the cell for receiving the information for determining whether it is a HeNB when the mobile terminal measures, the target cell of the measurement report will be disclosed. Also, as a specific example of the method for the mobile terminal to notify the information for determining whether it is a HeNB to the serving cell, a case of reporting as part of the parameters in the measurement report will be disclosed. Also, a case where the serving base station that has received the information for determining whether it is a HeNB performs a handover decision process for the MTCD in consideration of the information for determining whether the target cell of the measurement report is a HeNB will be disclosed.

[0532] After the processes of step ST1801 to step ST1803, step ST2301, and step ST2302 are performed as described above, in step ST2501, the mobile terminal notifies eNB_1 of a measurement report according to the measurement control information received in step ST1801. In this operation example, the mobile terminal notifies a measurement report of HeNB_A. The measurement report includes information for determining whether HeNB_A is a HeNB. Also, the measurement report may include information on whether HeNB_A is a HeNB.

[0533] In step ST2502, eNB_1 determines whether the mobile terminal that has notified the measurement report in step ST2501 is an MTCD. For this determination, the MTCD indicator in the UE Context (UE context) may be used. If eNB_1 determines in step ST2502 that the mobile terminal is an MTCD, it proceeds to step ST2503; if it determines that the mobile terminal is not an MTCD, it proceeds to step ST1704. By performing the process of step ST2502, handover decision processing for the MTCD can be performed in a form that distinguishes it from a normal UE according to the restrictions indicated by the MTCD restriction information.

[0534] In step ST2503, eNB_1 determines whether the target cell of the measurement report is a HeNB. Specific examples of this determination are disclosed below. It is determined based on the information for determining whether the target cell of the measurement report included in the measurement report received in step ST2501 is a HeNB, or on the information indicating whether it is a HeNB. If eNB_1 determines in step ST2503 that the target cell is not a HeNB, it proceeds to step ST1704.

[0535] If eNB_1 determines in step ST2503 that the target cell is a HeNB, it does not execute the processes of steps ST1704 and ST1705. Therefore, eNB_1 does not receive a response message to the handover request from HeNB_A in step ST1709. That is, eNB_1 does not notify the mobility control information (Mobility Control Information) to the mobile terminal that has notified the measurement report in step ST2501.

[0536] In this operation example, at step ST2501, eNB_1 receives "being a HeNB" as information on whether HeNB_A, which is the cell to be measured, is a HeNB. Therefore, at step ST2503, it is determined that the cell is a HeNB, and the processes of step ST1704, step ST1705, and step ST1711 are not executed.

[0537] By performing the process of step ST2503 in this way, even though the MTCD restricts the HeNB from being a handover destination candidate, it is possible to prevent the serving cell from receiving notification of mobility control information that designates the HeNB as a target cell in violation of that restriction.

[0538] According to Modification Example 2 of Embodiment 2, the following effects can be obtained. The serving base station can perform handover determination processing according to information for determining whether a handover destination candidate cell is a HeNB. Therefore, when the handover destination candidate cell is a HeNB, even though the MTCD restricts the HeNB from being a handover destination candidate, it is possible to prevent the serving cell from receiving notification of mobility control information that designates the HeNB as a target cell in violation of that restriction. As a result, it becomes possible to construct a communication system with unified judgment and obtain a stable communication system.

[0539] The serving base station can use the information for determining whether the target cell of the received measurement report is a HeNB for the following purposes. From the information for determining whether it is a HeNB, when it is determined that the cell is a HeNB, if the mobile terminal that has performed the measurement report is an MTCD, the measurement control information of the mobile terminal is adjusted. Among the mobile terminals under the umbrella, the measurement control information of the MTCD may be adjusted. Among the mobile terminals under the umbrella, the measurement control information of the MTCD in the connected state may be adjusted. A specific example of the adjustment of the measurement control information is to exclude the cell from the measurement target. As a result, it is possible to reduce the measurement of cells for which the MTCD cannot be selected as the target cell. Therefore, power consumption reduction of the MTCD can be achieved. The specific example of the method of excluding from the measurement target is the same as the modification example 2 of the first embodiment, and thus the description thereof is omitted.

[0540] This modification example is not limited to the application examples described above, and may be used in other application examples. Further, this modification example can be used in combination with the first embodiment, the modification example 1 of the first embodiment, the modification example 2 of the first embodiment, the modification example 3 of the first embodiment, the modification example 4 of the first embodiment, the modification example 5 of the first embodiment, the modification example 6 of the first embodiment, the second embodiment, or the modification example 1 of the second embodiment, including other application examples.

[0541] Modification Example 3 of Embodiment 2. In the modification example 3 of the second embodiment, another solution is disclosed for the same problem as in the modification example 2 of the second embodiment. The solution in the modification example 3 of the second embodiment is shown below. In this modification example, the description will be centered on the parts different from the solutions in the second embodiment and the modification example 2 of the second embodiment, and the parts not described will be the same as those in the second embodiment and the modification example 2 of the second embodiment.

[0542] The mobile terminal determines whether it is restricted from the cell based on the information on whether the cell of the measurement report is a HeNB. The mobile terminal notifies the serving base station of the determination result on whether the mobile terminal is restricted. The serving base station that receives the determination result performs handover decision processing in consideration of the determination result of the cell of the measurement report. The serving base station that receives the determination result may determine a target cell in consideration of the determination result of the cell of the measurement report.

[0543] Specific examples of the determination result by the mobile terminal on whether the mobile terminal is restricted are the same as those in Modification Example 3 of Embodiment 1, and thus the description is omitted.

[0544] When the mobile terminal determines that it is restricted, or when it determines that handover is impossible, or when it determines that it is impossible to select the cell as a target cell, the mobile terminal may not perform a measurement report. In that case, only the determination result may be notified, or the determination result may not be notified either. Thereby, radio resources can be effectively utilized.

[0545] Specific examples of the method for notifying the serving cell of the determination result on whether it is restricted are the same as those in "Specific Examples of the Method for Notifying MTCD Restriction Information to the Serving Cell" in Modification Example 2 of Embodiment 1.

[0546] Specific examples of the determination on whether the mobile terminal is restricted, considering the information for determining whether the mobile terminal that has received the information for determining whether it is a HeNB is a HeNB, are disclosed below.

[0547] When the mobile terminal in the connected state is an MTCD and determines that the measurement target cell is a HeNB based on the information for determining whether it is a HeNB, it is determined as "with restriction". Alternatively, it may be determined that handover using the cell as a target cell is impossible. Alternatively, it may be determined that it is impossible to select the cell as a target cell. Alternatively, it may be determined not to perform a measurement report.

[0548] When the mobile terminal in the connected state is an MTCD and it is determined that the measurement target cell is not a HeNB based on the information for determining whether it is a HeNB, it is determined as "no restriction". Alternatively, it may be determined that a handover with the cell as the target cell is possible. Alternatively, it may be determined that the cell can be selected as the target cell. Alternatively, it may be determined to perform a measurement report.

[0549] When the mobile terminal in the connected state is a mobile terminal other than an MTCD, it is determined as "no restriction". Alternatively, it may be determined that a handover with the cell as the target cell is possible. Alternatively, it may be determined that the cell can be selected as the target cell. Alternatively, it may not be necessary to make a determination considering the information for determining whether it is a HeNB.

[0550] The following discloses a specific example of the handover decision process of the serving base station that has received the determination result of whether the self-mobile terminal by the mobile terminal is restricted, considering this information. When the determination result is "restricted", or "handover with the cell as the target cell is impossible", or "the cell cannot be selected as the target cell", it is determined that a handover with the target cell as the target cell is impossible. It may be determined that the cell cannot be selected as the target cell. When the determination result is "no restriction", or "handover with the cell as the target cell is possible", or "the cell can be selected as the target cell", it is determined that a handover with the target cell as the target cell is possible. It may be determined that the cell can be selected as the target cell.

[0551] Next, with reference to FIGS. 32 and 33, a specific example of the sequence of the communication system in Modification 3 of Embodiment 2 will be described. FIGS. 32 and 33 are diagrams showing the sequence of the communication system in Modification 3 of Embodiment 2. FIGS. 32 and 33 are connected at the position of the boundary line BL7. Since the sequences shown in FIGS. 32 and 33 are similar to the sequences shown in FIGS. 17 to 19 and FIG. 28, the same step numbers are assigned to the same steps, and the common description is omitted.

[0552] In this operation example, it is assumed that an MTCD with eNB_1 as the serving base station, which is the source eNB, is moving closer to HeNB_A. Also, it is assumed that the measurement control information for the mobile terminal includes HeNB_A as the measurement target. In this operation example, a case where the mobile terminal uses the existing notification information "hnb-name" as a specific example of the information for determining whether the base station is a HeNB will be disclosed. Also, as a specific example of the cell in which the mobile terminal receives the information for determining whether it is a HeNB during measurement, the target cell of the measurement report will be disclosed. When the mobile terminal determines that the target cell of the measurement report is a HeNB, the determination result of whether the own mobile terminal is restricted is set to "with restriction", and when it is determined that the target cell of the measurement report is not a HeNB, the determination result of whether the own mobile terminal is restricted is set to "without restriction". Also, a case of an MTCD will be disclosed as a specific example of the mobile terminal that notifies the serving base station of the determination result of whether the own mobile terminal is restricted. Also, as a specific example of the method of notifying the serving cell of the determination result of whether the own mobile terminal is restricted with respect to the target cell of the measurement report, a case of reporting as part of the parameters in the measurement report will be disclosed.

[0553] After the processes of steps ST1801 to ST1803 and step ST2301 are performed as described above, in step ST2601, the mobile terminal (UE) determines whether the self-mobile terminal is an MTCD. For this determination, an MTCD indicator, which is information indicating that it is an MTCD stored in a USIM or the like, may be used. In step ST2601, if the mobile terminal determines that it is an MTCD, it proceeds to step ST2302, and if it determines that it is not an MTCD, it proceeds to step ST2605. By performing the process of step ST2601, in a normal UE, reception of information for determining whether it is an HeNB, determination of whether the self-mobile terminal is restricted, and notification to the serving base station can be made unnecessary.

[0554] After the process of step ST2302 is performed as described above, in step ST2602, the mobile terminal determines whether the target cell of the measurement report is an HeNB. Specific examples of this determination are disclosed below. The determination is made based on the information for determining whether the target cell of the measurement report received in step ST2301 is an HeNB. In step ST2602, if the mobile terminal determines that it is an HeNB, it proceeds to step ST2603, and if it determines that it is not an HeNB, it proceeds to step ST2604.

[0555] In this operation example, in step ST2301, the mobile terminal has received "hnb-name" by SIB9 as the notification information of HeNB_A. Therefore, in step ST2602, the mobile terminal determines that HeNB_A is an HeNB and proceeds to step ST2603. In step ST2603, the mobile terminal sets, in the measurement report, the determination result that the self-mobile terminal has "restriction" for the target cell of the measurement report.

[0556] In step ST2604, the mobile terminal sets, in the measurement report, the determination result that the self-mobile terminal has "no restriction" for the target cell of the measurement report.

[0557] In step ST2605, the mobile terminal notifies eNB_1 of a measurement report according to the measurement control information received in step ST1801. The measurement report includes a determination result as to whether the mobile terminal is restricted with respect to the cell targeted for the measurement report. In this operation example, the mobile terminal notifies a measurement report of HeNB_A. The measurement report includes a determination result of "restricted" for the mobile terminal with respect to HeNB_A.

[0558] In step ST2606, the serving base station performs handover determination processing in consideration of the measurement report received in step ST2605. In this operation example, eNB_1 has received from the mobile terminal a determination result of "restricted" for the mobile terminal with respect to HeNB_A in step ST2605. Based on this determination result, if eNB_1 does not determine to perform a handover with HeNB_A as the target cell, eNB_1 does not execute the processing of step ST1705. Therefore, since eNB_1 does not receive a response message to the handover request from HeNB_A in step ST1709, eNB_1 does not notify the mobile terminal that notified the measurement report in step ST2605 of the mobility control information in step ST1711.

[0559] According to Modification Example 3 of Embodiment 2 above, in addition to the effect of Modification Example 2 of Embodiment 2, the following effect can be obtained. In the serving base station, it is not necessary to perform handover determination processing in consideration of information for determining whether the cell targeted for the measurement report is a HeNB. Thereby, the processing load on the serving base station can be reduced.

[0560] This modification example is not limited to the application examples described above, and may be used in other application examples. Further, this modification example can be used in combination with Embodiment 1, Modification Example 1 of Embodiment 1, Modification Example 2 of Embodiment 1, Modification Example 3 of Embodiment 1, Modification Example 4 of Embodiment 1, Modification Example 5 of Embodiment 1, Modification Example 6 of Embodiment 1, Embodiment 2, Modification Example 1 of Embodiment 2, or Modification Example 2 of Embodiment 2, including other application examples.

[0561] Even when the base station constitutes a plurality of cells, each of the above embodiments can be applied to each cell.

[0562] In each of the above embodiments, the LTE system and the LTE-Advanced (LTE-A) system have been mainly described. However, the communication system of the present invention is also applicable to other communication systems.

[0563] Although the present invention has been described in detail, the above description is illustrative in all aspects and the present invention is not limited thereto. Innumerable modification examples not illustrated can be assumed without departing from the scope of the present invention.

Description of Reference Numerals

[0564] 1301 to 1304 MTCD, 1305 NB / eNB, 1306 SGSN / MME, 1307 HLR / HSS, 1308 MTC Server, 1309 MTC User, 1310 API, 1311 to 1314 Uu Interface, 1315 IuPS / S1 Interface, 1316 Gr / S6a Interface, 1317 Communication Operator Area.

Claims

1. A communication system including a base station device and a plurality of communication terminal devices capable of wireless communication with the base station device, The base station device notifies, as system information, communication terminal devices present within a communicable range, operation restriction information relating to restricted operations of restricted terminal devices which are part of the communication terminal devices whose operations are restricted among the plurality of communication terminal devices; The communication terminal device that has been notified of the operational restriction information determines whether or not the device itself is a restricted terminal device based on information stored in a SIM (Subscriber Identity Module), and operates in accordance with the operational restriction information if it is determined to be a restricted terminal device; The information for changing the operational restriction information is notified using a paging message; The communication system, wherein the operation restriction information is information for restricting transmission of an RRC (Radio Resource Control) connection request signal from the restricted terminal device to the base station device.

2. 2. The communication system according to claim 1, wherein the operation restriction information is information for restricting access to the base station device by the restricted terminal device.

3. A base station device capable of wireless communication with a plurality of communication terminal devices, notifying communication terminal devices present within a communicable range of operation restriction information relating to restricted operations of restricted terminal devices which are part of the plurality of communication terminal devices and whose operations are restricted, as system information; The information for changing the operational restriction information is notified using a paging message; The base station device, wherein the operation restriction information is information for restricting transmission of an RRC (Radio Resource Control) connection request signal from the restricted terminal device to the base station device.

4. A communication terminal device capable of wireless communication with a base station device, The device judges whether or not the device is a restricted terminal device based on information stored in a SIM (Subscriber Identity Module), and if it is judged to be a restricted terminal device, operates based on operation restriction information notified as system information by the base station device; The information for changing the operational restriction information is notified using a paging message; The communication terminal device, wherein the operation restriction information is information for restricting transmission of an RRC (Radio Resource Control) connection request signal from the restricted terminal device to the base station device.

Images