Communication control device, communication control method, and terminal device

Abstract

The present disclosure relates to a communication control device, a communication control method, and a terminal device. [Problem] To be able to reduce the load on a user equipment (UE) in carrier aggregation. [Solution] A communication control device is provided, equipped with: an acquisition unit for acquiring synchronization relationship information indicating which of a plurality of frequency bands for wireless communication are synchronized with each other; and a controller for controlling the transmission of the synchronization relationship information to a terminal device. The plurality of frequency bands includes at least one frequency band in which a common reference signal is not transmitted in at least one subframe among subframes in wireless communication, the subframe being a unit of time.

Description

[0001] This application is a divisional application of the PCT application filed on September 10, 2013, with national application number 201380055674.5 and entitled "Communication Control Device, Program, Communication Control Method and Terminal Device", which has entered the Chinese national phase. Technical Field

[0002] This disclosure relates to a communication control device, program, communication control method, and terminal device. Background Technology

[0003] Currently, 4G radio communication systems have been standardized by the 3rd Generation Partnership Project (3GPP). In 4G, technologies such as carrier aggregation, relay, and multi-user multiple-input multiple-output (MU-MIMO) have been noted.

[0004] Specifically, carrier aggregation is a technique that enables the processing of a bandwidth of 20MHz × 5 = 100MHz by jointly processing, for example, five frequency bands each with a bandwidth of 20MHz. According to carrier aggregation, the maximum throughput is expected to increase. Various techniques related to this carrier aggregation have been studied.

[0005] For example, Patent Document 1 discloses a technique for suppressing throughput reduction by controlling the allocation of management slots for each component carrier (CC) based on the determination result of the urgency of the handover.

[0006] Reference List

[0007] Patent documents

[0008] Patent Document 1: JP 2011-120196A Summary of the Invention

[0009] Technical issues

[0010] On the other hand, in 3GPP Release 11, New Carrier Types (NCTs) have been studied as new component carriers besides legacy CCs (existing CCs) that can maintain backward compatibility. Here, NCTs are considered as new types of CCs and the types of CCs mentioned above. In addition, as NCTs, NCTs that are synchronized with existing CCs (Synchronous New Carrier Type: SNCT) and NCTs that are not synchronized with LCCs (Asynchronous New Carrier Type: UNCT) have been studied.

[0011] The SNCT synchronizes with any legacy CC. When a UE acquires the synchronization status of its UE in one of the mutually synchronized SNCTs and legacy CCs, the synchronization status information can be used in the other CC. In other words, the UE may not need to acquire the synchronization status of its UE in the other CC. When a UE monitors the synchronization status of its UE in one of the mutually synchronized SNCTs and legacy CCs, the monitoring results can be used in the other CC. In other words, the UE may not need to monitor the synchronization status of its UE in the other CC.

[0012] A UNCT does not synchronize with any legacy CC, but it can synchronize with another UNCT. Therefore, when a UE acquires the synchronization status of a UE in one of two or more mutually synchronized UNCTs within a single CC, the information about the synchronization status can be used in the other CCs. In other words, the UE may not need to acquire the synchronization status of UEs in other CCs. Similarly, when a UE monitors the synchronization status of a UE in one of two or more mutually synchronized UNCTs within a single CC, the monitoring results can be used in the other CCs. Again, the UE may not need to monitor the synchronization status of UEs in other CCs.

[0013] However, in order for the UE to use information about the UE's synchronization status in one CC for another CC, there is a concern that a large load will be imposed on the UE.

[0014] For example, since frequency bands separate from the SNCT can exist within legacy CCs, the SNCT is not synchronized with all legacy CCs. Therefore, the UE checks the synchronization between the SNCT and each of the multiple legacy CCs to use information about the UE's synchronization status within the legacy CCs for the SNCT. In this way, a large load may be imposed on the UE.

[0015] For example, there is a possibility that one UNCT may synchronize with another UNCT, but not all UNCTs are necessarily synchronized. Therefore, the UE checks the synchronization between UNCTs in order to apply information about the synchronization status of the UE in one UNCT to another UNCT. In this way, a large load may be imposed on the UE.

[0016] Initially, when the UE does not use information about the synchronization status of the UE in one CC for another CC, the UE obtains the synchronization status of the UE in each CC and needs to monitor the synchronization status of the UE in each CC. In this way, a large load may be imposed on the UE.

[0017] Therefore, it is desirable to provide a structure that can reduce the load on the UE in carrier aggregation.

[0018] Solution to the problem

[0019] According to this disclosure, a communication control apparatus is provided, comprising: an acquisition unit configured to acquire synchronization relationship information indicating which frequency bands among a plurality of frequency bands used for radio communication are synchronized with each other; and a control unit configured to control the transmission of the synchronization relationship information to a terminal device. The plurality of frequency bands includes one or more frequency bands that are not used to transmit a common reference signal in at least one subframe, which is a unit of time in radio communication.

[0020] According to this disclosure, a program is provided that causes a computer to function as: an acquisition unit configured to acquire synchronization relationship information indicating which frequency bands among a plurality of frequency bands used for radio communication are synchronized with each other; and a control unit configured to control the transmission of the synchronization relationship information to a terminal device. The plurality of frequency bands includes one or more frequency bands that are not used to transmit a common reference signal in at least one subframe, which is a unit of time in radio communication.

[0021] According to this disclosure, a communication control method is provided, the method comprising: acquiring synchronization relationship information indicating which frequency bands among a plurality of frequency bands used for radio communication are synchronized with each other; and controlling the transmission of the synchronization relationship information to a terminal device. The plurality of frequency bands includes one or more frequency bands that are not used to transmit a common reference signal in at least one subframe, which is a unit of time in radio communication.

[0022] According to this disclosure, a terminal device is provided, the terminal device comprising: an acquisition unit configured to acquire synchronization relationship information upon receiving synchronization relationship information indicating which frequency bands among a plurality of frequency bands used for radio communication are synchronized with each other; and a control unit configured to perform control based on the synchronization relationship information for the purpose of synchronization among the plurality of frequency bands. The plurality of frequency bands includes one or more frequency bands that are not used to transmit a common reference signal in at least one subframe, which is a unit of time in radio communication.

[0023] According to this disclosure, a communication control device is provided, comprising: a control unit configured to control the transmission of signals using multiple frequency bands for radio communication. The multiple frequency bands include two or more frequency bands that are not used to transmit a common reference signal in at least one subframe, which is a unit of time in radio communication. The control unit controls the transmission in such a way that the common reference signal is transmitted at different frequencies using at least two of the two or more frequency bands.

[0024] According to this disclosure, a terminal device is provided, the terminal device comprising: a control unit configured to select a frequency band for radio communication of the terminal device from a plurality of frequency bands used for radio communication. The plurality of frequency bands includes two or more frequency bands that have not been used to transmit a common reference signal in at least one subframe, which is a unit of time in radio communication. The common reference signal is transmitted at different frequencies using at least two of the two or more frequency bands.

[0025] Beneficial effects of the invention

[0026] According to embodiments of this disclosure, the load on the UE can be reduced during carrier aggregation. Attached Figure Description

[0027] Figure 1 This is an explanatory diagram showing an example of the PCC for each UE.

[0028] Figure 2 This is an explanatory diagram illustrating an example of CRS transmitted using CC on the downlink.

[0029] Figure 3 This is an explanatory diagram illustrating an example of NCT. Five CC 30s are shown in... Figure 3 middle.

[0030] Figure 4 This is an explanatory diagram illustrating an example of the reduction in CRS along the frequency direction.

[0031] Figure 5 This is an explanatory diagram illustrating an example of the decrease in CRS along the time direction.

[0032] Figure 6 This is an explanatory diagram illustrating an example of a schematic structure of a radio communication system according to the first embodiment.

[0033] Figure 7 This is an explanatory diagram illustrating an example of the details of multiple CCs used for radio communication.

[0034] Figure 8 This is an explanatory diagram illustrating the first example of the synchronization relationship between the synchronous NCT and the legacy CC.

[0035] Figure 9 It means and Figure 8 The diagram illustrates an example of synchronization relationship information corresponding to the first example of synchronization relationship shown in the figure.

[0036] Figure 10 This is a diagram illustrating the second example of the synchronization relationship between the synchronous NCT and the legacy CC.

[0037] Figure 11 It means and Figure 10 The second example of the synchronization relationship shown in the diagram is an explanatory illustration of the synchronization relationship information corresponding to that example.

[0038] Figure 12 This is an explanatory diagram illustrating the first example of the synchronization relationship between asynchronous NCTs.

[0039] Figure 13 It means and Figure 12 The diagram illustrates an example of synchronization relationship information corresponding to the first example of synchronization relationship shown in the figure.

[0040] Figure 14 This is a diagram illustrating the second example of the synchronization relationship between asynchronous NCTs.

[0041] Figure 15 It means and Figure 14 The second example of the synchronization relationship shown in the diagram is an explanatory illustration of the synchronization relationship information corresponding to that example.

[0042] Figure 16 This is an explanatory diagram illustrating an example of the synchronization relationship between all CCs.

[0043] Figure 17 It means and Figure 16 The diagram illustrates the examples of synchronization relationships shown in the image, along with examples of synchronization relationship information.

[0044] Figure 18 This is an explanatory diagram illustrating another example of the details of the plurality of CCs used for radio communication.

[0045] Figure 19 This is an explanatory diagram illustrating an example of the synchronization relationship between NCTs.

[0046] Figure 20 It means and Figure 19 The diagram illustrates the examples of synchronization relationships shown in the image, along with examples of synchronization relationship information.

[0047] Figure 21 This is a block diagram illustrating an example of the structure of an eNodeB according to the first embodiment.

[0048] Figure 22 This is a block diagram illustrating an example of the structure of a UE according to the first embodiment.

[0049] Figure 23A This is a flowchart illustrating an example of the communication control process of the eNodeB according to the first embodiment.

[0050] Figure 23B This is a flowchart illustrating an example of a communication control process of a UE according to a first embodiment of the present disclosure.

[0051] Figure 24 This is an explanatory diagram illustrating a first example of CRS transmission according to a first variant of the first embodiment.

[0052] Figure 25 This is an explanatory diagram illustrating a second example of CRS transmission according to a first variant of the first embodiment.

[0053] Figure 26 This is an explanatory diagram illustrating a first example of synchronous monitoring according to a second variant of the first embodiment.

[0054] Figure 27 This is an explanatory diagram illustrating a second example of CRS transmission according to a second variant of the first embodiment.

[0055] Figure 28 This is a flowchart illustrating an example of a schematic flow of the communication control processing of a UE according to a second variant of the first embodiment.

[0056] Figure 29 This is an explanatory diagram illustrating an example of NCT where the transmission frequency of CRS is uniformly set.

[0057] Figure 30 This is an explanatory diagram illustrating an example of NCT according to the second embodiment.

[0058] Figure 31 This is a block diagram illustrating an example of the structure of an eNodeB according to the second embodiment.

[0059] Figure 32 It means and Figure 30 The diagram illustrates an example of the synchronization determination information corresponding to NCT.

[0060] Figure 33 This is a block diagram illustrating an example of the structure of a UE according to the second embodiment.

[0061] Figure 34A This is a flowchart illustrating an example of the communication control process of the eNodeB according to the second embodiment.

[0062] Figure 34B This is a flowchart illustrating an example of a schematic flow of the communication control processing of a UE according to the second embodiment.

[0063] Figure 35 This is an explanatory diagram illustrating an example of the transmission timing of the CRS in two NCTs associated with different transmission frequencies of the CRS.

[0064] Figure 36This is an explanatory diagram illustrating an example of the transmission timing of the CRS in two NCTs associated with different transmission frequencies of the CRS according to a first variant of the second embodiment.

[0065] Figure 37 This is an explanatory diagram illustrating an example of the transmission frequency of the CRS in each CC according to the synchronization relationship between component carriers (CCs).

[0066] Figure 38 This is a block diagram illustrating a first example of an eNodeB structure to which the technology according to embodiments of the present disclosure can be applied.

[0067] Figure 39 This is a block diagram illustrating a second example of an eNodeB structure to which the technology according to embodiments of the present disclosure can be applied.

[0068] Figure 40 This is a block diagram illustrating an example of a schematic structure of a smartphone to which the technology according to embodiments of the present disclosure can be applied.

[0069] Figure 41 This is a block diagram illustrating an example of a schematic structure of a car navigation device to which the technology according to embodiments of the present disclosure can be applied. Detailed Implementation

[0070] The preferred embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that in this specification and the drawings, structural elements having substantially the same function and structure are denoted by the same reference numerals, and repeated explanations of these structural elements are omitted.

[0071] The descriptions will proceed in the following order.

[0072] 1.3GPP technologies for radio communication

[0073] 2. Schematic structure of a radio communication system

[0074] 3. First Embodiment

[0075] 3.1. Overview

[0076] 3.2. Specific examples of synchronizing relational information

[0077] 3.3. Structure of each device

[0078] 3.3.1. Structure of eNodeB

[0079] 3.3.2. UE Structure

[0080] 3.4. Processing flow

[0081] 3.5. Variation Example

[0082] 3.5.1. First Variation Example

[0083] 3.5.2. Second variant example

[0084] 4. Second Embodiment

[0085] 4.1. Overview

[0086] 4.2. Structure of each device

[0087] 4.2.1. Structure of eNodeB

[0088] 4.2.2. UE Structure

[0089] 4.3. Processing flow

[0090] 4.4. Variation Example

[0091] 4.4.1. First variant example

[0092] 4.4.2. Second variant example

[0093] 5. Application Examples

[0094] 5.1. Applications related to eNodeB

[0095] 5.2. Applications related to UE

[0096] 6. Conclusion

[0097] <<<Technologies for Radio Communication in 1.3GPP>>>

[0098] First, as a premise, the technologies used for radio communication in 3GPP will be described.

[0099] (Carrier aggregation in version 10)

[0100] - Component carrier

[0101] In carrier aggregation version 10, up to five component carriers (CCs) are bundled for use in a UE. Each CC has a bandwidth of up to 20 MHz. In carrier aggregation, continuous CCs along the frequency direction are used in some cases, and discrete CCs along the frequency direction are used in others. In carrier aggregation, it is possible to configure the CCs to be used for each UE.

[0102] -Main CC and Secondary CC

[0103] In carrier aggregation, one of the multiple carriers used by the UE is a special carrier. This special carrier is called the primary component carrier (PCC). The remaining carriers are called secondary component carriers (SCCs). The PCC can be different for each UE. The following will refer to... Figure 1 To describe this in more detail.

[0104] Figure 1 This is an explanatory diagram showing examples of PCCs for each UE. UE 20A, UE 20B, and five CCs 1 through 5 are shown in... Figure 1 In this example, UE 20A uses two CCs, CC 1 and CC 2. UE 20A uses CC 2 as its PCC. On the other hand, UE 20B uses two CCs, CC 2 and CC 4. UE 20B uses CC 4 as its PCC. In this way, each UE can use a different CC as its PCC.

[0105] Since the PCC is the most important of the multiple CCs, the CC with the most stable communication quality is preferred. Which CC is used as the PCC actually depends on how it is installed.

[0106] The CC initially used by the UE to establish a connection is the PCC within the UE. The SCC is added to the PCC. That is, the PCC is the primary frequency band and the SCC is the secondary frequency band. The SCC is changed by deleting an existing SCC and adding a new SCC. The PCC is changed in existing inter-frequency handover sequences. In carrier aggregation, the UE cannot use only an SCC; it must use a PCC.

[0107] PCC is also known as the primary cell. SCC is also known as the secondary cell.

[0108] - Obtain the UE's synchronization status in CRS

[0109] In carrier aggregation, a common reference signal (CRS) is transmitted using each carrier control center (CC). The UE obtains the synchronization state of the UE in each CC through the CRS. The common reference signal is also known as the cell-specific reference signal.

[0110] (Background of NCT version 11)

[0111] In carrier aggregation, from the perspective of ensuring backward compatibility, legacy UEs (i.e., existing UEs) can be considered to use each carrier aggregation (CC). However, research has begun on more efficient definitions of CCs that do not require legacy UEs to use. That is, research has begun on the definition of a new CC called New Carrier Type (NCT) or Additional Carrier.

[0112] The ultimate motivation for NCT is to reduce the overhead of CC. Overhead refers to radio resources other than those used for transmitting user data. In other words, overhead is the radio resources used for control. When overhead increases, the radio resources used for transmitting user data may decrease. Therefore, an increase in overhead is undesirable. One reason for overhead is the presence of CRS in each CC in the downlink. The following will refer to... Figure 2 To describe this in more detail.

[0113] Figure 2 This is an explanatory diagram illustrating an example of a CRS transmitted using CC on the downlink. Several radio resource blocks (RBs) corresponding to a 20MHz CC are shown. Figure 2 Each RB has a width of 12 subcarriers along the frequency direction and a width of 7 orthogonal frequency division multiplexing (OFDM) symbols along the time direction. CRS is transmitted using each RB. That is, CRS is transmitted using all RBs present in the bandwidth of the CC along the frequency direction and in each time slot along the time direction. Therefore, CRS is transmitted using each CC and each subframe.

[0114] One purpose of CRS is to obtain the synchronization status of the UE. Synchronization exists in two forms: timing synchronization (synchronization along the time direction) and frequency synchronization (synchronization along the frequency direction). The UE can obtain its synchronization status with high accuracy along both the frequency and time directions using CRS. CRS is used to continuously obtain and maintain the synchronization status.

[0115] Another purpose of CRS is to enable the UE to properly demodulate downlink signals. The UE demodulates different received signals based on the phase of CRS.

[0116] The Common Reference Signal (CRS) is the most basic Reference Signal (RS) introduced in Release 8. On the other hand, currently, there are RSs such as the Channel State Information-Reference Signal (CSI-RS) that are transmitted intermittently. This RS is used to demodulate downlink signals. Therefore, the current primary purpose of the CRS is to obtain the synchronization state of the UE. Thus, when the synchronization state can be obtained, the frequency of CRS transmission can be reduced.

[0117] (Reduction of CRS studied in NTC version 11)

[0118] -Types of NCT

[0119] As NCT was studied in version 11, there are generally two types of NCT.

[0120] One of the two types of NCTs is the NCT synchronized with the legacy CC (that is, the existing CC). When the UE obtains the synchronization state in the legacy CC through the synchronization process in the legacy CC, the UE also obtains the synchronization state in the NCT synchronized with the legacy CC. This type of NCT is called the Synchronous NCT (hereinafter referred to as "SNCT"). Here, the synchronization process is performed by receiving the CRS to perform frequency synchronization and timing synchronization.

[0121] The other type of NCT is the NCT that is not synchronized with the legacy CC. The UE needs to obtain the synchronization status in the NCT through the synchronization process in the NCT. This type of NCT is called an asynchronous NCT (hereinafter referred to as "UNCT"). Since synchronization processing is required in the UNCT, the CRS is sent in the UNCT.

[0122] As mentioned above, SNCT and UNCT exist as NCTs. The following will refer to... Figure 3 Describe specific examples of SNCT and UNCT.

[0123] Figure 3 This is an explanatory diagram illustrating an example of NCT. Five CC 30s are shown in... Figure 3 In this example, CC 30A and CC 30B are legacy CCs. CC 30A and CC 30B are synchronized with each other. CC 30C, CC 30D, and CC 30E are NCTs. More specifically, CC 30C is an SNCT synchronized with both CC 30A and CC 30B, which are legacy CCs. CC 30D and CC 30E are UNCTs synchronized with neither CC 30A nor CC 30B. In this example, CC 30D and CC 30E are not synchronized with each other.

[0124] - Reduction of CRS in asynchronous NCT

[0125] Since the CRS transmitted using legacy CC is sent to maintain synchronization and demodulate the received signal, the CRS is redundant. On the other hand, since the CIS-RS has been standardized as an RS for demodulation in versions after version 10, the CRS can be reduced. Therefore, the extent to which the CRS can be reduced while maintaining the synchronization state of the UE has been investigated. In particular, as a reduction of the CRS for asynchronous NCT (i.e., UNCT), the reduction of the CRS along the frequency direction and the reduction of the CRS along the time direction have been investigated.

[0126] As a reduction in the CRS along the frequency direction, for example, the number of RBs used to transmit the CRS is reduced to 6 RBs, 25 RBs, or 50 RBs. The following will refer to... Figure 4 Describe this in detail.

[0127] Figure 4 This is an explanatory diagram illustrating examples of CRS reduction along the frequency direction. The cases where the number of RBs used to transmit the CRS is reduced to 6 RBs along the frequency direction and the cases where the number of RBs used to transmit the CRS is reduced to 25 RBs along the frequency direction are shown in the diagram. Figure 4 In this way, instead of transmitting all the CRS in the RBs along the frequency direction, a limited number of CRS in the RBs are transmitted.

[0128] On the other hand, as a reduction in CRS along the time direction, for example, the CRS transmission period is considered to be 5ms or 10ms. (Refer to...) Figure 5 Describe this in detail.

[0129] Figure 5 This is an explanatory diagram illustrating an example of the reduction in CRS along the time direction. The cases where the CRS transmission period is 5ms and the CRS transmission period is 10ms are shown in... Figure 5 In this way, instead of sending the CRS of all time slots or subframes along the time direction, a limited number of subframes' CRSs are sent.

[0130] As described above, methods for reducing CRS in both the frequency and time directions have been investigated. As an evaluation of whether synchronization is maintained, an accuracy of approximately 500 Hz was assessed in an environment with an SNR of -8 dB. The results showed that, in an SNR environment of -8 dB, 25 RBs were required to transmit CRS every 5 ms.

[0131] -Reduction of CRS in synchronous NCT

[0132] On the other hand, since the Synchronous NCT (SNCT) is synchronized with the legacy CC, existing CRS can be largely deleted in the SNCT.

[0133] (Synchronous monitoring process)

[0134] The UE monitors its synchronization status based on the block error rate (BLER) of the Physical Downlink Control Channel (PDCCH). In other words, the UE detects synchronization deviations based on the BLER of the PDCCH. For example, the UE detects a synchronization deviation when the BLER of the PDCCH is equal to or greater than 10%.

[0135] A timer starts when a predetermined number of synchronization deviations are detected. Then, when the timer expires, a radio link failure (RLF) is identified. Upon identification of an RLF, the UE stops all transmissions for 40 ms from the start of RLF identification to avoid interfering with another UE. Afterward, the UE performs the RRC re-establishment procedure, including cell selection and random access.

[0136] The UE performs the aforementioned synchronization monitoring on the PCC, but not on the SCC. When no PDCCH is detected in the SCC, the UE disables the SCC.

[0137] <<<2. Schematic Structure of a Radio Communication System>>>

[0138] Next, we will refer to Figure 6 A schematic structure of a radio communication system according to a first embodiment of the present disclosure is described. Figure 6 This is an explanatory diagram illustrating an example of a schematic structure of a radio communication system according to a first embodiment of the present disclosure. The radio communication system conforms to a range of communication standards, such as Long Term Evolution (LTE). (Refer to...) Figure 6 The radio communication system includes eNodeB 100 and UE 200.

[0139] The eNodeB 100 performs radio communication with the UE 200 located within cell 10. For example, the eNodeB 100 uses multiple component carriers (CCs) to perform radio communication.

[0140] For example, the eNodeB 100 can use multiple carrier aggregation (CCs) to perform radio communication with a UE 200 simultaneously. In other words, the eNodeB 100 supports carrier aggregation.

[0141] Specifically, in the first embodiment, the plurality of CCs includes one or more CCs that were not used to transmit CRS in at least one subframe, which is a unit of time in radio communication. More specifically, for example, the plurality of CCs includes one or more NCTs.

[0142] UE 200 performs radio communication with eNodeB 100 of cell 10. For example, UE 200 can use multiple carrier aggregation (CCs) simultaneously in radio communication. Specifically, UE 200 can use multiple CCs simultaneously to perform radio communication with eNodeB 100 of cell 10. That is, UE 200 supports carrier aggregation.

[0143] The specific details will be described below in <<<3. First Embodiment>>> and <<<4. Second Embodiment>>>.

[0144] <<<3. First Embodiment>>>

[0145] Next, we will refer to Figures 7 to 28 A first embodiment of this disclosure is described.

[0146] <<3.1. Overview>>

[0147] First, an overview of the first embodiment of this disclosure will be described.

[0148] In 3GPP Release 11, as mentioned above, NCT has been studied as a new component carrier besides legacy CCs (existing CCs) that can maintain backward compatibility. Here, NCT is considered a new type of CC and the aforementioned type of CC. In addition, NCT synchronized with existing CCs (SNCT) and NCT not synchronized with LCCs (UNCT) have been studied as NCTs.

[0149] Because the SNCT is synchronized with any legacy CC, when the UE acquires the synchronization status of the UE in one of the mutually synchronized SNCTs and legacy CCs, the information about the synchronization status can be used in the other CC. In other words, the UE may not need to acquire the synchronization status of the UE in the other CC. Similarly, when the UE monitors the synchronization status of the UE in one of the mutually synchronized SNCTs and legacy CCs, the monitoring results can be used in the other CC. Again, the UE may not need to monitor the synchronization status of the UE in the other CC.

[0150] A UNCT does not synchronize with any legacy CC, but it can synchronize with another UNCT. Therefore, when a UE acquires the synchronization status of a UE in one of two or more mutually synchronized UNCTs within a single CC, the synchronization status information can be used in the other CCs. In other words, the UE may not need to acquire the synchronization status of UEs in other CCs. Similarly, when a UE monitors the synchronization status of a UE in one of two or more mutually synchronized UNCTs within a single CC, the monitoring results can be used in the other CCs. Again, the UE may not need to monitor the synchronization status of UEs in other CCs.

[0151] However, in order for the UE to use information about the UE's synchronization state in one CC for another CC, there is a concern that a large load will be imposed on the UE.

[0152] For example, since the frequency band separated from the SNCT can exist in the legacy CCs, the SNCT is not synchronized with all the legacy CCs. Therefore, the UE checks the synchronization between the SNCT and each of the multiple legacy CCs to use information about the UE's synchronization status in the legacy CCs for the SNCT. This check includes, for example, using information about the UE's synchronization status in the multiple legacy CCs to confirm whether data can be received in the NCT if there are no errors in the NCT. In this way, a large load is placed on the UE.

[0153] For example, there is a possibility that a UNCT may synchronize with another UNCT, but not all UNCTs are necessarily synchronized. Therefore, the UE checks the synchronization between UNCTs to use information about the synchronization status of the UE in one UNCT for another UNCT. This check includes, for example, using information about the synchronization status of the UE in multiple UNCTs to confirm whether data can be received in another UNCT without errors. In this way, a large load may be imposed on the UE.

[0154] Initially, when the UE does not use information about the synchronization status of the UE in one CC for another CC, the UE obtains the synchronization status of the UE in each CC and needs to monitor the synchronization status of the UE in each CC. In this way, a large load is imposed on the UE.

[0155] Therefore, in the first embodiment of this disclosure, the load on the UE can be reduced during carrier aggregation.

[0156] Specifically, according to the first embodiment, the plurality of CCs used for radio communication includes one or more CCs that are not used to transmit CRS in at least one subframe. More specifically, for example, the one or more CCs are one or more NCTs. In addition, the eNodeB 100-1 sends synchronization relationship information indicating which of the plurality of CCs are synchronized with each other to the UE 100-1.

[0157] <<3.2. Specific Examples of Synchronizing Relationship Information>>

[0158] Next, we will refer to Figures 7 to 20 Describe a specific example of the synchronization relationship information sent from the eNodeB to the UE.

[0159] (Synchronization relationship between legacy CC and synchronous NCT)

[0160] As described above, the plurality of CCs used for radio communication include one or more frequency bands not used to transmit CRS in at least one subframe. Additionally, for example, the plurality of CCs include one or more different CCs used to transmit CRS in each subframe. More specifically, for example, the plurality of CCs include one or more NCTs and one or more legacy CCs. The following will refer to... Figure 7 To describe this in more detail.

[0161] Figure 7 This is an explanatory diagram illustrating an example of the details of multiple CCs used for radio communication. Five CCs 30 used for radio communication are shown in... Figure 7For example, CC 30 is used for radio communications in cell 10. Of the five CC 30s, CC 30A and CC 30B are legacy CCs. CC 30C, CC 30D, and CC 30E are NCTs.

[0162] For example, synchronization relationship information indicates at least which frequency band among one or more frequency bands is synchronized with which of the one or more different frequency bands. More specifically, for example, synchronization relationship information indicates at least which NCT among one or more NCTs is synchronized with which legacy CC among one or more legacy CCs. In other words, synchronization relationship information indicates the synchronization relationship between NCTs and legacy CCs.

[0163] For example, the one or more CCs include one or more synchronization bands that are synchronized with any one of the one or more different frequency bands. Synchronization relationship information at least indicates which of the one or more synchronization bands is synchronized with which of the one or more different frequency bands. More specifically, for example, the one or more NCTs include one or more synchronous NCTs (i.e., SNCTs). Synchronization relationship information at least indicates which of the one or more SNCTs is synchronized with which of the one or more legacy CCs. In other words, synchronization relationship information indicates the synchronization relationship between SNCTs and legacy CCs. The following will refer to... Figure 8 and 9 The first concrete example describing this and will refer to Figure 10 and 11 A second concrete example illustrating this point.

[0164] Figure 8 This is an explanatory diagram illustrating the first example of the synchronization relationship between the synchronous NCT and the legacy CC. Like... Figure 7 Same, Figure 8 Two legacy CCs and three NCTs are shown. More specifically, CC 30C is a synchronous NCT (i.e., SNCT) that is synchronized with any legacy CC. In this example, CC 30C is synchronized with both CC 30A and CC 30B, which are legacy CCs. CC 30D and CC 30E are asynchronous NCTs (i.e., UNCT) that are not synchronized with any legacy CC.

[0165] Figure 9 It means and Figure 8 The diagram illustrates an example of synchronization relationship information corresponding to the first example of the synchronization relationship shown. Information indicating the synchronization relationship between the legacy CC and SNCT is shown as follows. Figure 9 The table in. Figure 8 In the example, CC 30C, as an SNCT, is synchronized with CC 30A and CC 30B, which are legacy CCs. Therefore, as Figure 9 As shown, the SYNC indicating synchronization is displayed in the columns corresponding to CC 30C and CC 30A, and in the columns corresponding to CC 30C and CC 30B. Synchronization relationship information indicates the synchronization relationship between SNCT and legacy CC in this manner, for example. Figure 9 In this illustration, synchronization relationship information is shown as a table for descriptive purposes, but the synchronization relationship information can be any type of information indicating the synchronization relationship between CCs. This also applies to the following figures.

[0166] Figure 10 This is a diagram illustrating a second example of the synchronization relationship between the synchronous NCT and the legacy CC. (See diagram for example.) Figure 10 As shown in the example, CC 30A and CC 30B, which are legacy CCs, are not synchronized with each other. CC 30C is synchronized with CC 30B, which is a legacy CC, but not with CC 30A, which is a legacy CC.

[0167] Figure 11 It means and Figure 10 The second example of the synchronization relationship shown in the diagram illustrates the example of synchronization relationship information. Figure 10 In the example, CC 30C, as an SNCT, is synchronized with CC 30B, as a legacy CC, but not with CC 30A, which is also a legacy CC. Therefore, as Figure 11 As shown, the SYNC indicating synchronization is only displayed in the column corresponding to CC 30C and CC 30B. Synchronization relationship information indicates the synchronization relationship between SNCT and legacy CC in this manner, for example.

[0168] exist Figure 9 and 11 In the example, the synchronization relationship information only indicates the synchronization relationship between the SNCT and the legacy CC, but the first embodiment is not limited to this. The synchronization relationship information can also indicate the synchronization relationship between the NCT and the legacy CC. That is, the synchronization relationship information can also indicate which legacy CC each NCT synchronizes with. In this case, the NCT that is not synchronized with any legacy CC in the synchronization relationship information is the UNCT. The NCT that is synchronized with any legacy CC in the synchronization relationship information is the SNCT.

[0169] By sending this synchronization relationship information, UE 200-1 does not need to individually verify which legacy CC is synchronized with the SNCT. For example, UE 200-1 can use information about the synchronization status of the legacy CC synchronized with the SNCT within the SNCT. In this way, the load on UE 200-1 can be reduced.

[0170] (Synchronization relationship between UNCTs)

[0171] For example, synchronization information indicates at least which frequency bands are synchronized with each other within the one or more frequency bands. More specifically, for example, synchronization information indicates at least which NCTs are synchronized with each other among the preceding one or more NCTs. In other words, synchronization information indicates the synchronization relationship between NCTs.

[0172] For example, the plurality of CCs includes one or more different CCs used to transmit CRS in each subframe. The one or more CCs include two or more asynchronous frequency bands that are not synchronized with any of the one or more different frequency bands. Synchronization relationship information at least indicates which of the two or more asynchronous frequency bands are synchronized with each other. Specifically, for example, the plurality of CCs includes one or more legacy CCs, and the one or more NCTs include two or more asynchronous CCs (i.e., UNCTs) that are not synchronized with any of the one or more legacy CCs. Synchronization relationship information at least indicates which of the two or more UNCTs are synchronized with each other. In other words, synchronization relationship information indicates the synchronization relationship between UNCTs. The following will refer to... Figure 12 and 13 The first concrete example describing this and will refer to Figure 14 and 15 A second concrete example illustrating this point.

[0173] Figure 12 This is an explanatory diagram illustrating the first example of a synchronization relationship between asynchronous NCTs. Like... Figure 7 Same, Figure 12 Two legacy CCs and three NCTs are shown. More specifically, CC 30D and CC 30E are non-synchronous NCTs (i.e., UNCTs) that are not synchronized with any legacy CC. In this example, CC 30D and CC 30E are not synchronized with each other. CC 30C is a synchronous NCT (i.e., SNCT) that is synchronized with one legacy CC.

[0174] Figure 13 It means and Figure 12 The diagram illustrates an example of synchronization relationship information corresponding to the first example of synchronization relationship shown. Information indicating the synchronization relationship between UNCTs is shown as... Figure 13 The table in. Figure 12 In the example, CC 30D and CC 30E, as UNCTs, are not synchronized with each other. Therefore, as... Figure 13 As shown, the SYNC indicating synchronization is not displayed in the column corresponding to CC30D and CC 30E. Synchronization relationship information indicates the synchronization relationship between UNCTs in this manner, for example.

[0175] Figure 14This is a diagram illustrating a second example of the synchronization relationship between asynchronous NCTs. (See diagram for example.) Figure 14 As shown in the image, in this example, CC 30D and CC 30E are synchronized with each other.

[0176] Figure 15 It means and Figure 14 The second example of the synchronization relationship shown in the diagram illustrates the example of synchronization relationship information. Figure 14 In the example, CC30D and CC 30E, acting as UNCTs, are synchronized with each other. Therefore, as... Figure 15 As shown, the SYNC indicating synchronization is displayed in the column corresponding to CC 30D and CC 30E. Synchronization relationship information indicates the synchronization relationship between UNCTs in this manner, for example.

[0177] By sending this synchronization relationship information, UE 200-1 does not need to individually verify which UNCT is synchronized with which UNCT. For example, UE 200-1 can use information about the synchronization status of one UNCT for another UNCT synchronized with that UNCT. In this way, the load on UE 200-1 can be reduced.

[0178] (Synchronization relationships between all CCs)

[0179] The above has described examples of synchronization relationship information indicating the synchronization relationship between legacy CCs and SNCTs, as well as the synchronization relationship between UNCTs. Synchronization relationships can be indicated in the synchronization relationship information indicating the synchronization relationship between all CCs. The following will refer to... Figure 16 and 17 Specific examples to illustrate this.

[0180] Figure 16 This is an explanatory diagram illustrating an example of the synchronization relationships between all CCs. (See also...) Figure 16 For example, CC 30A as a legacy CC, CC 30B as a legacy CC, and CC 30C as a SNCT are synchronized with each other. CC 30D and CC 30E as UNCTs are synchronized with each other.

[0181] Figure 17 It means and Figure 16 The diagram illustrates examples of synchronization relationships and their corresponding information. All synchronization relationships between CCs are shown in... Figure 17 In this example, the SYNC indicating synchronization is displayed in the columns corresponding to CC30A and CC 30B, CC 30A and CC 30C, CC 30B and CC 30C, and CC 30D and CC 30E. Synchronization relationship information indicates the synchronization relationship between CCs in this way, for example.

[0182] (There is no synchronization relationship between NCTs with legacy CC)

[0183] The examples of multiple CCs used for radio communication including legacy CCs have been described above, but legacy CCs may not be included in the multiple CCs. That is, each of the multiple CCs may be a CC that was not used to transmit CRS in at least one subframe. In other words, each of the multiple CCs may be an NCT. The following will refer to... Figure 18 To describe this in more detail.

[0184] Figure 18 This is another explanatory diagram illustrating the details of multiple CCs used for radio communication. Five CCs 30 used for radio communication are shown in... Figure 18 For example, CC 30 is used for radio communication in cell 10. Each of the five CC 30s is an NCT.

[0185] Synchronization relationship information indicates which CCs are synchronized with each other among the plurality of CCs. That is, in this example, the synchronization relationship information indicates which NCTs are synchronized with each other among the plurality of NCTs. The following will refer to... Figure 19 and 20 Specific examples to illustrate this.

[0186] Figure 19 This is an explanatory diagram illustrating an example of the synchronization relationship between NCTs. Like... Figure 18 Same, Figure 19 Five CCs are shown as NCT. In this example, CC 30G and CC 30H are synchronized with each other. CC 30I and CC 30J are synchronized with each other. The other combinations of CCs are not synchronized with each other.

[0187] Figure 20 It means and Figure 19 The diagram illustrates examples of synchronization relationships and their corresponding information. All synchronization relationships between CCs are shown in... Figure 20 In this example, the SYNC indicating synchronization is shown in the columns corresponding to CC 30G and CC 30H, and in the columns corresponding to CC 30I and CC 30J. Synchronization relationship information indicates the synchronization relationship between CCs in this way, for example.

[0188] By sending this synchronization relationship information, UE 200-1 does not need to individually verify which NCT is synchronizing with which NCT. For example, UE 200-1 can use information about the synchronization status of one NCT for another NCT that is synchronizing with that NCT. In this way, the load on UE 200-1 can be reduced.

[0189] <<3.3. Structure of Each Device>>

[0190] Next, examples of the structure of eNodeB 100-1 and UE 200-1 according to the first embodiment of this disclosure will be described.

[0191] <3.3.1. Structure of eNodeB>

[0192] First, refer to Figure 21 An example describing the structure of eNodeB100-1 according to a first embodiment of the present disclosure. Figure 21 This is a block diagram illustrating an example of the structure of eNodeB 100-1 according to a first embodiment of the present disclosure. (Refer to...) Figure 21 The eNodeB 100-1 includes an antenna unit 110, a radio communication unit 120, a network communication unit 130, a storage unit 140, and a control unit 150.

[0193] (Antenna Element 110)

[0194] Antenna unit 110 receives radio signals and outputs the received radio signals to radio communication unit 120. Antenna unit 110 transmits the transmission signal output by radio communication unit 120.

[0195] (Radio communication unit 120)

[0196] Radio communication unit 120 performs radio communication with UE 200-1 located within cell 10. For example, radio communication unit 120 performs radio communication using multiple CCs simultaneously.

[0197] For example, the radio communication unit 120 can simultaneously use multiple CCs to perform radio communication with a UE 200. That is, the eNodeB 100 supports carrier aggregation.

[0198] (Network communication unit 130)

[0199] Network communication unit 130 communicates with another communication node. For example, network communication unit 130 communicates with another eNodeB, mobility management entity (MME), etc.

[0200] (Storage Unit 140)

[0201] Storage unit 140 stores programs and data used for the operation of eNodeB 100-1.

[0202] For example, storage unit 140 stores synchronization relationship information indicating which CCs are synchronized with each other among a plurality of CCs used for radio communication. Specific examples of synchronization relationship information have been described above.

[0203] (Control Unit 150)

[0204] The control unit 150 provides various functions of the eNodeB 100-1.

[0205] Specifically, in the first embodiment, the control unit 150 acquires synchronization relationship information indicating which frequency bands among the plurality of CCs used for radio communication are synchronized with each other. More specifically, for example, the control unit 150 acquires synchronization relationship information stored in the storage unit 140.

[0206] Then, control unit 150 controls the transmission of synchronization relationship information to UE 200. More specifically, for example, control unit 150 generates system information including synchronization relationship information and causes radio communication unit 120 to transmit the system information. Thus, UE 200-1 is able to receive the synchronization relationship information. The synchronization relationship information can also be transmitted to UE 200-1 via radio resource control (RRC) signaling.

[0207] The plurality of CCs includes one or more CCs that were not used to transmit CRS in at least one subframe. More specifically, the plurality of CCs includes one or more NCTs.

[0208] As described above, by sending synchronization relationship information, the load on UE 200-1 can be reduced in carrier aggregation. That is, when synchronization relationship information is sent from eNodeB 100-1 to UE 200-1, UE 200-1 does not need to individually verify which CC is synchronized with which CC. For example, when mutually synchronized CCs exist (e.g., legacy CC and SNCT, UNCT and UNCT), UE 200-1 can use information about the synchronization status of UE 200-1 in one CC for the other CC. In this way, the load on UE 200-1 can be reduced.

[0209] <3.3.2. UE Structure>

[0210] First, refer to Figure 22 An example of the structure of UE 200-1 according to a first embodiment of the present disclosure is described. Figure 22 This is a block diagram illustrating an example of the structure of UE 200-1 according to a first embodiment of the present disclosure. (Refer to...) Figure 22 The UE 200-1 includes an antenna unit 210, a radio communication unit 220, a storage unit 230, and a control unit 240.

[0211] (Antenna element 210)

[0212] Antenna unit 210 receives radio signals and outputs the received radio signals to radio communication unit 220. Antenna unit 210 transmits the transmission signal output by radio communication unit 220.

[0213] (Radio communication unit 220)

[0214] Radio communication unit 220 performs radio communication with eNodeB 100-1 of cell 10. For example, radio communication unit 220 can use multiple CCs simultaneously. Specifically, radio communication unit 220 can use multiple CCs simultaneously to perform radio communication with eNodeB 100-1. That is, UE 200-1 supports carrier aggregation.

[0215] (Storage unit 230)

[0216] Storage unit 230 stores programs and data for the operation of UE 200-1.

[0217] For example, storage unit 230 stores synchronization relationship information indicating which CCs are synchronized with each other among a plurality of CCs used for radio communication. Specifically, storage unit 230 stores the synchronization relationship information, for example, when control unit 240 acquires the synchronization relationship information.

[0218] (Control Unit 240)

[0219] The control unit 240 provides various functions of the UE 200-1.

[0220] Specifically, in the first embodiment, when synchronization relationship information indicating which CCs among a plurality of CCs used for radio communication are synchronized with each other is received, the control unit 240 acquires the synchronization relationship information. Specifically, for example, when the eNodeB 100-1 transmits system information including synchronization relationship information, the radio communication unit 220 receives the system information. Then, the control unit 240 acquires the synchronization relationship information from the received system information.

[0221] Control unit 240 performs control based on synchronization relationship information for the purpose of synchronization among the plurality of CCs.

[0222] For example, control unit 240 designates mutually synchronized control rooms (CCs) based on synchronization relationship information. Control unit 240 acquires the synchronization status of UE 200-1 in some of the mutually synchronized CCs and applies the synchronization status information to the remaining CCs. More specifically, for example, control unit 240 acquires the synchronization status of UE 200-1 in one of the mutually synchronized CCs via a synchronization record (CRS). Then, control unit 240 applies the acquired synchronization status information of UE 200-1 in said one CC to the remaining CCs. Therefore, control unit 240 can acquire the synchronization status of UE 200-1 in the remaining CCs without using a CRS. That is, the load on UE 200-1 is reduced.

[0223] The plurality of CCs includes one or more CCs that were not used to transmit a common reference signal in at least one subframe. Specifically, for example, the plurality of CCs includes one or more NCTs. CCs that are synchronized with each other are, for example, legacy CCs and SNCTs or two or more UNCTs.

[0224] <<3.4. Processing Flow>>

[0225] Next, we will refer to Figure 23A and 23B An example of communication control processing according to a first embodiment of the present disclosure is described.

[0226] (Communication control processing on the eNodeB side)

[0227] Figure 23A This is a flowchart illustrating an example of a communication control process of eNodeB 100-1 according to a first embodiment of the present disclosure.

[0228] In step S401, the control unit 150 acquires the synchronization relationship information stored in the storage unit 140.

[0229] Next, in step S403, the control unit 150 generates system information including synchronization relationship information.

[0230] Then, in step S405, the control unit 150 causes the radio communication unit 120 to transmit system information including synchronization relationship information. That is, the radio communication unit 120 transmits system information including synchronization relationship information. Then, the process returns to step S401.

[0231] (Communication control processing on the UE side)

[0232] Figure 23B This is a flowchart illustrating an example of a communication control process of UE 200-1 according to a first embodiment of the present disclosure.

[0233] In step S421, when eNodeB 100-1 sends system information including synchronization relationship information, radio communication unit 220 receives the system information.

[0234] In step S423, the control unit 240 obtains synchronization relationship information from the received system information.

[0235] In step S425, the control unit 240 performs control based on the synchronization relationship information for the purpose of synchronization among the plurality of CCs. Then, the process returns to step S421.

[0236] <<3.5. Variation Example>>

[0237] Next, we will refer to Figures 24 to 28 First and second variations of the first embodiment of this disclosure are described.

[0238] <3.5.1. First Variation Example>

[0239] First, refer to Figure 24 and 25 A first variant of the first embodiment is described.

[0240] (Overview)

[0241] In the prior art, CRS is sent using each CC. For this reason, even when using NCT, it is possible to send CRS using each NCT as in the prior art.

[0242] However, as described above, when UE 200-1 acquires the synchronization status of a certain UNCT, UE 200-1 can use the information about UE 200-1's synchronization status for another UNCT synchronized with that UNCT. Therefore, from the viewpoint of efficient use of radio resources, it is undesirable to use each of the two or more mutually synchronized UNCTs to transmit CRS.

[0243] When each of the plurality of CCs used for radio communication is an NCT (that is, when there are no legacy CCs) and UE 200-1 obtains the synchronization state of UE 200-1 in a certain NCT, UE 200-1 can use the information about the synchronization state for another NCT synchronized with that NCT. Therefore, from the viewpoint of efficient use of radio resources, it is undesirable to use each of the two or more mutually synchronized NCTs to transmit CRS.

[0244] Therefore, in a first variant of the first embodiment, the one or more CCs not used to transmit CRS in at least one subframe include two or more mutually synchronized CCs. CRS is transmitted using some of the two or more CCs in at least one subframe, and the remaining CCs are not used.

[0245] Therefore, radio resources can be used efficiently. In other words, the radio resources used for transmitting control signals can be reduced.

[0246] (Specific example of CRS sending)

[0247] Specifically, for example, the NCTs included in multiple CCs used for radio communication include two or more mutually synchronized NCTs. When there is no legacy CC, the two or more NCTs are, for example, two or more UNCTs or two or more NCTs. A CRS is transmitted using some of the two or more NCTs, and the remaining NCTs are not used to transmit the CRS. The following will refer to... Figure 24 and 25 Specific examples to illustrate this.

[0248] Figure 24 This is an explanatory diagram illustrating a first example of CRS transmission according to a first variant of the first embodiment. Five CCs 30 for radio communication are shown in... Figure 24 In this example, among the five CC 30s, CC 30A and CC 30B are legacy CCs, and CC 30C, CC 30D, and CC 30E are NCTs. More specifically, CC 30D and CC 30E are asynchronous NCTs (i.e., UNCTs) that are not synchronized with any legacy CCs. In this example, CC 30D and CC 30E, as UNCTs, are synchronized with each other. In this case, CRS is sent using CC 30D, but not using CC 30E. UE 200-1 obtains the synchronization status of UE 200-1 in CC 30D and uses the information about the synchronization status in CC 30E.

[0249] Figure 25 This is an explanatory diagram illustrating a second example of CRS transmission according to a first variant of the first embodiment. Five CCs 30 for radio communication are shown in... Figure 25In this example, each of the five CC 30s is an NCT. Here, CC 30G and CC 30H are synchronized with each other. CC 30I and CC 30J are synchronized with each other. The other combinations of CCs are not synchronized with each other. In this case, CRS is sent using CC 30F, CC 30H, and CC 30I, but not using CC 30G and CC 30J. UE 200-1 obtains the synchronization status of UE 200-1 in CC 30H and uses the information about the synchronization status in CC 30G. UE 200-1 obtains the synchronization status of UE 200-1 in CC 30I and uses the information about the synchronization status in CC 30J.

[0250] (Structure of each device)

[0251] -eNodeB 100-1: Control Unit 150

[0252] The control unit 150 of the eNodeB 100 controls the transmission of signals in each CC, such that in at least one subframe, some of the two or more mutually synchronized CCs are used to transmit the CRS, and the remaining CCs are not used to transmit the CRS.

[0253] More specifically, for example, the control unit 150 of the eNodeB 100 causes the radio communication unit 120 to transmit the CRS using some of the two or more mutually synchronized NCTs. The control unit 150 causes the radio communication unit 120 to transmit the CRS without using the remaining NCTs of the two or more NCTs.

[0254] As an example, control unit 150 causes radio communication unit 120 to transmit the CRS using each NCT according to the CRS transmission settings. These settings include, for example, the CRS transmission period along the time direction, the CRS transmission target RB along the frequency direction, and the transmission position within the RB. Radio communication unit 120 transmits the CRS using each NCT according to the CRS transmission settings. Specifically, for example, signal-to-resource element (RE) mapping is performed by radio communication unit 120. Radio communication unit 120 maps the CRS to REs according to the CRS transmission settings. Subsequently, radio communication unit 120 transmits the CRS.

[0255] As another example, the mapping of the signal to the RE can be performed by the control unit 150. The control unit 150 can map the CRS to the RE according to a predetermined transmission frequency of the CRS. The radio communication unit 120 can transmit the CRS using the RE. In this case, for example, the control unit 150 includes communication processing circuitry configured to perform some processing of the physical layer of the radio communication protocol.

[0256] The control unit 150 controls the transmission of signals in this manner, for example.

[0257] -eNodeB 100-1: Radio Communication Unit 120

[0258] The radio communication unit 120 of the eNodeB 100 transmits a CRS using some of two or more mutually synchronized CCs in at least one subframe, and does not use the remaining CCs among the two or more CCs to transmit the CRS. More specifically, for example, the radio communication unit 120 of the eNodeB 100 transmits the CRS using some of the two or more mutually synchronized NCTs. The radio communication unit 120 does not use the remaining NCTs among the two or more NCTs to transmit the CRS.

[0259] <3.5.2. Second Variation Example>

[0260] First, refer to Figures 26 to 28 A second variation of the first embodiment is described.

[0261] (Overview)

[0262] In the first embodiment, as described above, UE 200-1 performs control based on synchronization relationship information for the purpose of synchronization among multiple CCs used for radio communication. For example, UE 200-1 obtains the synchronization status of UE 200-1 in some of the mutually synchronized CCs via CRS. Then, UE 200-1 uses the obtained information about the synchronization status of UE 200-1 in some CCs for the remaining CCs.

[0263] In a second variation of the first embodiment, the one or more CCs not used to transmit CRS in at least one subframe include two or more mutually synchronized CCs. UE 200-1 monitors the synchronization status of UE 200-1 in some of the two or more CCs, and does not monitor the synchronization status of UE 200-1 in the remaining two or more CCs.

[0264] For example, UE 200-1 uses the monitoring results of the synchronization status of UE 200 in some CCs for the rest of the CCs.

[0265] As described above, when there are mutually synchronized NCTs and UE 200-1 monitors the synchronization status of UE 200-1 in some NCTs, UE 200-1 may not need to monitor the synchronization status of UE 200-1 in the remaining CCs. In this way, the load on UE 200-1 can be reduced.

[0266] (Specific examples of synchronous monitoring)

[0267] Specifically, for example, the plurality of CCs used for radio communication include two or more mutually synchronized NCTs. The two or more NCTs are, for example, two or more UNCTs, or, when there is no legacy CC, two or more NCTs. UE 200-1 monitors the synchronization status of UE 200-1 in some of the two or more NCTs. On the other hand, UE 200-1 does not monitor the synchronization status of UE 200-1 in the remaining NCTs among the two or more NCTs. Hereinafter, reference will be made to... Figure 26 and 27 Specific examples to illustrate this.

[0268] Figure 26 This is an explanatory diagram illustrating a first example of synchronous monitoring according to a second variant of the first embodiment. Five CCs 30 for radio communication are shown in... Figure 26 In this example, among the five CC 30s, CC 30A and CC 30B are legacy CCs, and CC 30C, CC 30D, and CC 30E are non-synchronous NCTs (NCTs). More specifically, CC 30D and CC 30E are non-synchronous NCTs (i.e., UNCTs) that are not synchronized with any legacy CCs. In this example, CC 30D and CC 30E, as UNCTs, are synchronized with each other. In this case, UE 200-1 monitors the synchronization status of UE 200-1 in CC 30D, but does not monitor the synchronization status of UE 200-1 in CC 30E. UE 200-1 uses the monitoring results of the synchronization status of UE 200-1 in CC 30D for CC 30E.

[0269] Figure 27 This is an explanatory diagram illustrating a second example of CRS transmission according to a second variant of the first embodiment. (Refer to...) Figure 27 Five CC 30s used for radio communication are shown. In this example, all five CC 30s are NCTs. Here, CC 30G and CC 30H are synchronized with each other. CC 30I and CC 30J are synchronized with each other. The other combinations of CCs are not synchronized with each other. In this case, UE 200-1 monitors the synchronization status of UE 200-1 in CC 30F, CC 30H, and CC 30I, but does not monitor the synchronization status of UE 200-1 in CC 30G and CC 30J. UE 200-1 uses the monitoring results of the synchronization status of UE 200 in CC 30H for CC 30G. UE 200-1 uses the monitoring results of the synchronization status of UE 200 in CC 30I for CC 30J.

[0270] (Structure of each device)

[0271] -UE 200-1: Control Unit 240

[0272] The control unit 240 of UE 200-1 performs control for the purpose of synchronization among the plurality of CCs based on synchronization relationship information. In particular, in a second variant of the first embodiment, the control unit 240 monitors the synchronization status of UE 200-1 in some of the two or more CCs, and does not monitor the synchronization status of UE 200-1 in the remaining CCs.

[0273] For example, control unit 240 designates mutually synchronized NCTs based on synchronization relationship information. Control unit 240 monitors the synchronization status of UE 200-1 in some CCs within the mutually synchronized NCTs, but does not monitor the synchronization status of UE 200-1 in the remaining NCTs. More specifically, for example, control unit 240 monitors the presence of synchronization issues in some NCTs based on the BLER of the PDCCH. In other words, UE 200-1 detects synchronization deviations in some NCTs based on the BLER of the PDCCH. For example, UE 200-1 detects a synchronization deviation when the BLER is less than a predetermined value (e.g., 10%).

[0274] When UE 200-1 detects a predetermined number of synchronization deviations, the timer starts. Subsequently, when UE 200-1 detects a synchronization state before the timer expires, UE 200-1 stops the timer. The reason for stopping the timer in this way is that if an NCT is immediately disabled due to a detected synchronization deviation, it has a significant impact on other NCTs that are synchronized with that NCT.

[0275] When the timer expires, UE 200-1 disables the NCT. UE 200-1 also similarly uses information about the synchronization status of UE 200-1 in the NCT to disable the NCT.

[0276] The existing SCC (that is, the SCC of carrier aggregation in version 10) is disabled only when no PDCCH is detected. On the other hand, through the above synchronization and monitoring processes, even if the synchronization monitoring target NCT synchronized with other NCTs is an SCC, the synchronization monitoring target NCT is not disabled simply because no PDCCH is detected. Therefore, since the synchronization monitoring target NCT is not simply disabled, it is difficult to have an adverse effect on other NCTs synchronized with the NCT.

[0277] For example, as in existing SCC technology, NCTs that are not synchronized with any NCT ​​are disabled by UE 200-1. That is, UE 200-1 disables NCTs that are not synchronized with any NCT ​​only when no PDCCH is detected.

[0278] (Processing flow)

[0279] Next, we will refer to Figure 28 An example of communication control processing of UE 200-1 according to a second variant of the first embodiment is described. Figure 28 This is a flowchart illustrating an example of a schematic flow of the communication control process of UE 200-1 according to a second variant of the first embodiment.

[0280] In step S501, the control unit 240 monitors the synchronization status of UE 200-1 in one of the mutually synchronized NCTs, and does not monitor the synchronization status of UE 200-1 in the other CCs.

[0281] In step S503, the control unit 240 determines whether a synchronization state of UE 200-1 is detected in the synchronization monitoring target NCT. If no synchronization state is detected, the process proceeds to step S505. Otherwise (that is, when a synchronization deviation is detected), the process proceeds to step S507.

[0282] In step S505, if the timer has already started, the control unit 240 stops the timer. Then, the process returns to step S501.

[0283] In step S507, the control unit 240 determines whether the timer has been started. If the timer has been started, the process proceeds to step S511. Otherwise, the process proceeds to step S509.

[0284] In step S509, the control unit 240 starts the timer.

[0285] In step S511, the control unit 240 determines whether the timer has expired. If the timer expires, the process proceeds to step S513. Otherwise, the process returns to step S501.

[0286] In step S513, the control unit 240 disables the synchronous monitoring target NCT. In step S515, the control unit 240 disables the NCT synchronized with the synchronous monitoring target NCT.

[0287] In step S517, the control unit 240 performs a reconnection process for the disabled NCT. When the NCT is activated, the process returns to step S501.

[0288] Referenced Figures 7 to 28 A first embodiment of this disclosure is described. According to the first embodiment, the load on the UE can be reduced in carrier aggregation.

[0289] <<<4. Second Embodiment>>>

[0290] Next, we will refer to Figures 29 to 37 A second embodiment of this disclosure is described.

[0291] <<4.1. Overview>>

[0292] First, an overview of the second embodiment of this disclosure will be described.

[0293] In 3GPP Release 11, as mentioned above, NCT has been studied as a new component carrier that can maintain backward compatibility, in addition to legacy CC (which already exists). The main motivation for NCT is to reduce the overhead of CC (that is, to reduce the radio resources used for control).

[0294] To reduce overhead, the extent to which CRS can be reduced while maintaining the UE's synchronization state has been investigated. It was found that in an environment with an SNR of -8dB, CRS must be transmitted every 5ms using 25 RBs.

[0295] However, in reality, since SNR varies depending on location within the cell, it's possible that even if a UE located at a certain location within the cell has an SNR of -8dB, a UE closer to the cell center might have an SNR of 10dB. Therefore, for example, when CRS is transmitted uniformly every 5ms using 25 RBs in the NCT, many CRSs across the entire NCT might be transmitted due to UEs in poorer environments. Consequently, there are concerns that overhead may not be adequately reduced.

[0296] Therefore, in the second embodiment of this disclosure, the overhead caused by the common reference signal (CRS) can be further reduced while acquiring the synchronization state of the terminal device (UE).

[0297] Specifically, in the second embodiment, the plurality of CCs used for radio communication include two or more CCs that are not used to transmit CRS in at least one subframe. More specifically, for example, the two or more CCs are, for example, two or more NCTs. Then, CRS is transmitted between at least two of the two or more CCs at different frequencies. Hereinafter, reference will be made to... Figure 29 and 30 Specific examples to illustrate this.

[0298] Figure 29 This is an explanatory diagram illustrating an example of NCT where the transmission frequency of CRS is uniformly set. Five CC 30s for radio communication are shown in... Figure 29 In the five CC 30s, CC 30K is a legacy CC and the other CC 30s are NCTs. In the NCTs, CRS is transmitted uniformly every 5ms using 25 RBs.

[0299] Figure 30This is an explanatory diagram illustrating an example of NCT according to a second embodiment of the present disclosure. Like Figure 29 Same, Figure 30 This indicates five CC 30s used for radio communication. Of the five CC 30s, CC 30K is a legacy CC, and the other CC 30s are NCTs. In CC 30L and CC 30O, a CRS is transmitted every 5 ms using 25 RBs. In CC 30M and CC 30N, a CRS is transmitted every 10 ms using 6 RBs. Figure 30 In the example shown, with Figure 29 Compared to the examples shown, this reduces the overhead caused by CRS in the CC 30M and CC 30N even more.

[0300] In this way, when there are NCTs used to transmit CRS at different frequencies, UE 200 can selectively use the NCT according to the environment. For example, UE 200 in an environment with low SNR uses the NCT used to transmit CRS at a higher frequency. UE 300 in an environment with high SNR uses the NCT used to transmit CRS at a lower frequency. As a result, UE 200 can obtain its own synchronization status. (See reference...) Figure 30 As mentioned above, this can reduce the expenses caused by CRS.

[0301] <<4.2. Structure of Each Device>>

[0302] Next, examples of eNodeB 100-2 and UE 200-2 according to a second embodiment of this disclosure will be described.

[0303] <4.2.1. Structure of eNodeB>

[0304] First, refer to Figure 31 and 32 An example describing the structure of eNodeB 100-2 according to a second embodiment of the present disclosure. Figure 31 This is a block diagram illustrating an example of the structure of the eNodeB 100-2 according to a second embodiment of the present disclosure. (Refer to...) Figure 31 The eNodeB 100-2 includes an antenna unit 110, a radio communication unit 120, a network communication unit 130, a storage unit 141, and a control unit 151.

[0305] Here, there are no differences in the antenna unit 110, radio communication unit 120, and network communication unit 130 between the first and second embodiments. Therefore, the storage unit 141 and the control unit 151 will be described here.

[0306] (Storage unit 141)

[0307] Storage unit 141 stores programs and data used for the operation of eNodeB 100-2.

[0308] For example, storage unit 141 stores synchronization capability determination information for determining whether UE 200-2 can synchronize in each of the two or more frequency bands not used to transmit CRS in at least one subframe. More specifically, for example, the synchronization capability determination information is information used to determine whether UE 200-2 can synchronize in each of the two or more NCTs. Specific examples of synchronization capability determination information will be described below.

[0309] (Control Unit 151)

[0310] The control unit 151 provides various functions for the eNodeB 100-2.

[0311] - Signal transmission control related to CRS

[0312] Specifically, in the second embodiment, the control unit 151 controls the transmission of signals in the plurality of CCs used for radio communication. The plurality of CCs includes two or more CCs that are not used to transmit CRS in at least one subframe. The control unit 151 controls the transmission such that CRS is transmitted at mutually different frequencies in at least two of the two or more CCs.

[0313] More specifically, for example, the control unit 151 controls the transmission of signals such that at least two of the two or more NCTs transmit CRS at different frequencies. For example, the control unit 151 controls the transmission of signals such that CRS is transmitted every 5 ms using 25 RBs in one NCT and every 10 ms using 6 RBs in another NCT.

[0314] As an example, control unit 151 causes radio communication unit 120 to transmit the CRS using each NCT according to the CRS transmission settings. These settings include, for example, the CRS transmission period along the time direction, the CRS transmission target RB along the frequency direction, and the transmission position within the RB. Radio communication unit 120 transmits the CRS using each NCT according to the CRS transmission settings. Specifically, for example, signal-to-resource element (RE) mapping is performed by radio communication unit 120. Radio communication unit 120 maps the CRS to REs according to the CRS transmission settings. Subsequently, radio communication unit 120 transmits the CRS.

[0315] As another example, the mapping of the signal to the RE can be performed by the control unit 151. The control unit 151 can map the CRS to the RE according to a predetermined CRS transmission frequency. The radio communication unit 120 can transmit the CRS using the RE.

[0316] Control unit 151 controls the transmission of signals in this manner, for example.

[0317] - Synchronization capability determines the transmission of information

[0318] Control unit 151 acquires synchronization capability determination information for determining whether UE 200-2 can synchronize in each of the two or more frequency bands not used to transmit CRS in at least one subframe. More specifically, for example, the synchronization capability determination information is information for determining whether UE 200-2 can synchronize in each of the two or more NCTs. Control unit 151 acquires the synchronization capability determination information stored in storage unit 141.

[0319] Control unit 151 controls the transmission of synchronization capability determination information to UE 200-2. More specifically, for example, control unit 151 generates system information including synchronization capability determination information and causes radio communication unit 120 to transmit the system information. Thus, UE 200-2 is able to receive the synchronization capability determination information. The synchronization capability determination information can be transmitted to UE 200-2 via RRC signaling.

[0320] When this information is provided, UE 200-2 can determine which NCT is needed to achieve synchronization, even though the transmission frequency of CRS varies depending on the NCT. Therefore, UE 200-2 can more reliably achieve synchronization without using trial and error by selecting and using the appropriate NCT based on the environment (that is, establishing a connection with eNodeB 100-1 in the appropriate NCT).

[0321] For example, synchronization capability determination information includes information about the transmission frequency of the CRS in each of the two or more CCs that were not used to transmit the CRS in at least one subframe. More specifically, for example, synchronization capability determination information includes information about the transmission frequency of the CRS in each of the two or more CCs. The transmission frequency includes one or both of the frequency along the time direction and the frequency along the frequency direction. Hereinafter, reference will be made to... Figure 32 Describe specific examples of how synchronization capabilities determine information.

[0322] Figure 32 It means and Figure 30 The diagram illustrates an example of synchronization determination information corresponding to an NCT. The transmission frequency of the CRS in each NCT is shown in the diagram. Figure 32 In China. (See reference...) Figure 30The transmission frequency of the CRS in CC 30L and CC 30O, which are part of the NCT, is a period of 5 ms in the time direction and a width of 25 RBs in the frequency direction. The transmission frequency of the CRS in CC 30M and CC 30N is a period of 10 ms in the time direction and a width of 6 RBs in the frequency direction. The synchronization capability determination information includes, for example, information indicating the transmission frequency of the CRS in each NCT in this manner. Of course, the synchronization capability determination information does not necessarily include a specific value of the CRS transmission frequency. For example, the synchronization capability determination information includes identification information (e.g., ID) for identifying the transmission frequency of the CRS.

[0323] When this information is provided, UE 200-2 can know the transmission frequency of the CRS in each NCT. Therefore, UE 200-2 can more reliably achieve synchronization without using trial and error by selecting an appropriate CRS transmission frequency based on the environment and using the CRS associated with that transmission frequency.

[0324] Synchronization capability determination information may include information about the recommended communication quality for each of the two or more CCs that were not used to transmit CRS in at least one subframe. For example, in Figure 30 and 32 In the example, synchronization capability determination information may include a recommended SNR (e.g., SNR = -8dB) as information about the recommended communication quality in CC 30L and CC 30O.

[0325] When this information is provided, UE 200-2 is able to determine the level of communication quality (e.g., SNR) required to achieve synchronization in each NCT. Therefore, UE 200-2 can more reliably achieve synchronization without using trial and error by selecting an appropriate NCT based on the actual SNR in each NCT and using that NCT.

[0326] Synchronization capability determination information may include information regarding power control for each of the two or more CCs that were not used to transmit CRS in at least one subframe. For example, synchronization capability determination information may include information indicating whether a power boost is applied in two or more NCTs.

[0327] When this information is provided, UE 200-2 can determine which NCT is needed to more easily achieve a synchronized state. Therefore, UE 200-2 can more reliably achieve a synchronized state without using trial and error by selecting and using the appropriate NCT.

[0328] - Assign CC to UE

[0329] For example, control unit 151 selects a CC for radio communication of UE 200-2 from among a plurality of CCs used for radio communication.

[0330] Specifically, for example, control unit 151 selects the SCC for radio communication of UE 200-2. Here, control unit 151 selects the SCC for radio communication of UE 200-2 based on, for example, the SNR of UE 200-2 in each CC and the transmission frequency of CRS in each CC. For example, control unit 151 selects the NCT used to transmit CRS at a higher frequency (e.g., 5ms and 25 RBs) as the SCC for UE 200-2 existing in an environment with low SNR. Control unit 151 selects the NCT used to transmit CRS at a lower frequency (e.g., 10ms and 6 RBs) as the SCC for UE 200-2 existing in an environment with high SNR. As a result of the selection, UE 200-2 is able to achieve a synchronization state in the selected CC.

[0331] Even within the same UE 200-2, the SNR varies depending on the CC, but significantly varies depending on the location of the UE 200-2. For example, depending on the fading environment of the UE 200-2, in some cases, there can be a difference of approximately 10 dB between the SNR for one CC and the SNR for another CC. The difference in SNR caused by the CC can be increased due to the location of the UE 200-2. Therefore, for example, when the UE 200-2 is far from the center of cell 10 (e.g., with a large timing advance value), the control unit 151 may select the NCT used to transmit the CRS at a higher frequency (e.g., 5 ms and 25 RBs) as the SCC of the UE 200-2. When the UE 200-2 is close to the center of cell 10 (e.g., with a small timing advance value), the control unit 151 may select the NCT used to transmit the CRS at a lower frequency (e.g., 10 ms and 6 RBs) as the SCC of the UE 200-2.

[0332] For a specific UE 200-2, in some cases, the SNR of the first NCT associated with a lower frequency (e.g., 10 ms and 6 RBs) is significantly greater than the SNR of the second NCT associated with a higher frequency (e.g., 5 ms and 25 RBs). In this case, the control unit 151 may select the first NCT as the SCC of the specific UE 200-2.

[0333] -Dynamic change of CRS transmission frequency in NCT

[0334] Control unit 151 can change the transmission frequency of CRS in each NCT. More specifically, for example, control unit 151 acquires the SNR for each UE 200-2 (e.g., the SNR of each UE 200-2 in the legacy CC). Then, control unit 151 determines the transmission frequency of CRS in each NCT based on the distribution of the acquired SNR. Thus, a more suitable transmission frequency can be set according to the environment of cell 10.

[0335] <4.2.2. UE Structure>

[0336] First, refer to Figure 33 An example of UE 200-2 according to a second embodiment of the present disclosure is described. Figure 33 This is a block diagram illustrating an example of the structure of UE 200-2 according to the second embodiment. (Refer to...) Figure 33 The UE 200-2 includes an antenna unit 210, a radio communication unit 220, a storage unit 231, and a control unit 241.

[0337] (Storage unit 231)

[0338] Storage unit 230 stores programs and data for the operation of UE 200-2.

[0339] For example, storage unit 231 stores synchronization capability determination information for determining whether UE 200-2 can synchronize in each of the two or more frequency bands not used to transmit CRS in at least one subframe. Specifically, for example, the synchronization capability determination information is information used to determine whether UE 200-2 can synchronize in each of the two or more NCTs. Storage unit 231 stores the synchronization capability determination information when control unit 241 acquires it.

[0340] (Control Unit 241)

[0341] - Selection of CC for radio communication

[0342] The control unit 241 provides various functions of the UE 200-2.

[0343] Specifically, in the second embodiment, the control unit 241 selects a CC for radio communication of UE 200-2 from a plurality of CCs used for radio communication. The plurality of CCs includes two or more CCs that were not used to transmit CRS in at least one subframe. CRS is transmitted at mutually different frequencies in at least two of the two or more CCs.

[0344] More specifically, for example, the plurality of CCs includes two or more NCTs. At least two of the two or more NCTs transmit CRS at mutually different frequencies. Control unit 241 selects a suitable CC for UE 200-2 and uses that CC to establish a connection with eNodeB 100-2. The CC selected by UE 200-2 for this connection is used by UE 200-2 as PCC, for example, in this manner.

[0345] - Selection of CC based on synchronization capability

[0346] When the control unit 241 receives synchronization capability determination information used to determine whether UE 200-2 can synchronize in each of the two or more frequency bands, it acquires the synchronization capability determination information. Specifically, for example, the synchronization capability determination information is information used to determine whether UE 200-2 can synchronize in each of the two or more NCTs. When eNodeB 100-2 transmits system information including the synchronization capability determination information, the radio communication unit 220 receives the system information. Then, the control unit 241 acquires the synchronization capability determination information from the received system information.

[0347] Control unit 241 selects a CC for radio communication of UE 200-2 from among the plurality of CCs based on synchronization capability determination information. Specifically, for example, control unit 241 measures signal strength by transmitting CRS in each CC. Control unit 241 calculates SNR based on signal strength and noise power. Control unit 241 selects a suitable CC based on synchronization capability determination information (e.g., CRS transmission frequency) and SNR in each CC. For example, UE 200-2, existing in an environment with low SNR, selects an NCT for transmitting CRS at a higher frequency (e.g., 5ms and 25 RBs) and uses this NCT to establish a connection with eNodeB 100-2. UE 300, existing in an environment with high SNR, selects an NCT for transmitting CRS at a lower frequency (e.g., 10ms and 6 RBs) and uses this NCT to establish a connection with eNodeB 100-2. As a result, UE 200 is able to obtain the synchronization state of UE 200 in the selected CC.

[0348] For example, when UE 200-2 is far from the center of cell 10 (e.g., with a large timing advance value), control unit 241 may select an NCT to transmit CRS at a higher frequency (e.g., 5ms and 25 RBs). When UE 200-2 is close to the center of cell 10 (e.g., with a small timing advance value), control unit 241 may select an NCT to transmit CRS at a lower frequency (e.g., 10ms and 6 RBs). However, when the SNR of the first NCT associated with the lower frequency (e.g., 10ms and 6 RBs) CRS is significantly greater than the SNR of the second NCT associated with the higher frequency (e.g., 5ms and 25 RBs) CRS, UE 200-2 may select the first NCT.

[0349] When the synchronization capability determination information includes a recommended SNR, the control unit 241 may select an NCT associated with an SNR equal to or greater than the recommended SNR. When the synchronization capability determination information includes information indicating whether to apply a power boost, the control unit 241 may select an NCT taking that information into account.

[0350] <<4.3. Processing Flow>>

[0351] Next, we will refer to Figure 34A and 34B An example of communication control processing according to a first embodiment of the present disclosure is described.

[0352] (Communication control processing on the eNodeB side)

[0353] Figure 34A This is a flowchart illustrating an example of the communication control process of the eNodeB 100-2 according to the second embodiment. This communication control process is performed to send synchronization capability determination information.

[0354] In step S701, the control unit 151 acquires the synchronization capability determination information stored in the storage unit 141.

[0355] Next, in step S703, the control unit 151 generates system information including synchronization capability determination information.

[0356] In step S705, the control unit 151 causes the radio communication unit 120 to send system information including synchronization capability determination information. That is, the radio communication unit 120 sends system information including synchronization capability determination information. Then, the process returns to step S701.

[0357] (Communication control processing on the UE side)

[0358] Figure 34BThis is a flowchart illustrating an example of a schematic flow of the communication control process of UE 200-2 according to the second embodiment. This communication control process is performed to determine the information selection CC based on synchronization capability.

[0359] In step S721, when eNodeB 100-1 sends system information including synchronization capability determination information, radio communication unit 220 receives the system information.

[0360] In step S723, the control unit 241 obtains synchronization capability determination information from the received system information.

[0361] In step S725, the control unit 240 selects a CC for radio communication of the UE from the plurality of CCs based on synchronization capability determination information. Then, the process ends.

[0362] <<4.4. Variation Example>>

[0363] Next, we will refer to Figures 35 to 37 First and second variations of the first embodiment of this disclosure are described.

[0364] <4.4.1. First Variation Example>

[0365] First, refer to Figure 35 and 36 A first variant of the second embodiment is described.

[0366] (Overview)

[0367] In the second embodiment, as described above, the transmission frequency of the CRS can differ between NCTs. Therefore, in some cases, the transmission frequency of the CRS along the time direction also differs between NCTs. Hereinafter, reference will be made to... Figure 35 Specific examples to illustrate this.

[0368] Figure 35 This is an explanatory diagram illustrating examples of CRS transmission timing in two NCTs associated with different CRS transmission frequencies. The transmission timings of the CRS in the NCT that transmits CRS along the time direction at a period of 5 ms and the transmission timings of the CRS in the NCT that transmit CRS along the time direction at a period of 10 ms are shown. Figure 35 Therefore, for example, when the transmission frequency of CRS along the time direction differs between NCTs, there is a possibility that the transmission timing of CRS (e.g., the subframes for transmitting CRS) may deviate between NCTs. As a result, the power consumption of UE 200-2 increases due to the increased operating time of UE 200-2.

[0369] Therefore, in the first variant, some or all of the subframes for transmitting the CRS using the NCT (Network Transmission Center) at a lower frequency along the time direction are subframes for transmitting the CRS using the CC (Network Transmission Center) at a higher frequency. That is, the subframes for transmitting the CRS are matched as closely as possible between the NCTs. The following will refer to... Figure 36 Specific examples to illustrate this.

[0370] Figure 36 This is an explanatory diagram illustrating an example of the CRS transmission timing in two NCTs associated with different CRS transmission frequencies according to a first variant of the second embodiment. The transmission timings of the CRS in the NCT that transmits the CRS at a period of 5 ms along the time direction and the transmission timings of the CRS in the NCT that transmit the CRS at a period of 10 ms along the time direction are shown. Figure 36 In this example, all the transmission timings (subframes for transmitting CRS) of the CRS in the NCT used to transmit CRS at a period of 10ms match some of the transmission timings (subframes for transmitting CRS) of the CRS in the NCT used to transmit CRS at a period of 5ms. Figure 35 Compared to the examples shown in [the text], in [the text] Figure 36 In the example shown, fewer subframes are sent for CRS.

[0371] Therefore, by reducing the operating time of UE 200-2, it is possible to prevent an increase in the power consumption of UE 200-2.

[0372] (Structure of each device)

[0373] -eNodeB 100-2: Control Unit 151

[0374] The two or more CCs not used to transmit CRS in at least one subframe include a low-frequency CC used to transmit CRS at a first frequency along the time direction and a high-frequency CC used to transmit CRS at a second frequency higher than the first frequency along the time direction. More specifically, for example, two or more NCTs include, for example, an NCT used to transmit CRS every 10 ms using 6 RBs and an NCT used to transmit CRS every 5 ms using 25 RBs.

[0375] Control unit 151 controls the transmission such that some or all subframes of CRS transmission using low-frequency CC are changed to subframes of CRS transmission using high-frequency CC. More specifically, for example, control unit 151 controls the transmission such that all subframes of CRS transmission using NCT with 6 RBs every 10 ms are changed to subframes of CRS transmission using NCT with 25 RBs every 5 ms.

[0376] <4.4.2. Second Variation Example>

[0377] Next, we will refer to Figure 37 A second variation of the second embodiment is described.

[0378] (Overview)

[0379] As described above, NCTs that are synchronized with an existing CC (SNCT) and NCTs that are not synchronized with an LCC (UNCT) have been studied as NCTs. As described in the first embodiment, information about the synchronization status of UE 200 in some of the mutually synchronized UNCTs can also be used in the remaining UNCTs.

[0380] However, for example, if the CRS transmission frequency in one of the synchronized UNCTs is low (e.g., CRS is transmitted every 10ms using 6 RBs) and UE 200 exists in an environment with low SNR, there is a possibility that the synchronization state is not achieved in said one UNCT. As a result, there is concern that UE 200 may not use UNCTs in radio communications.

[0381] Therefore, in the second variant, the CRS is transmitted at different frequencies in the mutually synchronized frequency bands of the mutually synchronized NCTs. (Refer to...) Figure 37 Specific examples to illustrate this.

[0382] Figure 37 This is an explanatory diagram illustrating an example of the transmission frequency of the CRS in each CC according to the synchronization relationship between component carriers (CCs). Five CCs 30 used for radio communication are shown in... Figure 37 In this configuration, among the five CC 30s, CC 30K is a legacy CC and the other CC 30s are NCTs. CC 30L and CC 30M are synchronized with each other. CC 30N and CC 30O are synchronized with each other. In this configuration, for example, CRS is sent every 5ms using 25 RBs in CC 30L, and every 10ms using 6 RBs in CC 30M. CRS is sent every 5ms using 25 RBs in CC 30O, and every 10ms using 6 RBs in CC 30N.

[0383] Because UE 200-2 can more reliably achieve synchronization in one of the mutually synchronized NCTs through CRS transmission, it can use NCTs more reliably. For example, even in environments with poor communication quality, UE 200-2 can achieve synchronization in an NCT associated with a higher CRS transmission frequency. UE 200-2 can then use information about the synchronization status in another NCT.

[0384] (Structure of each device)

[0385] -eNodeB 100-2: Control Unit 151

[0386] Control unit 151 controls the transmission of signals such that CRS is transmitted at different frequencies in at least two or more mutually synchronized CCs that are not used to transmit the common reference signal in at least one subframe. More specifically, for example, when there are mutually synchronized first and second NCTs, control unit 151 causes radio communication unit 120 to transmit CRS every 10 ms using 6 RBs in the first NCT and every 5 ms using 25 RBs in the second NCT.

[0387] <<<5. Application Examples>>>

[0388] The technology related to this disclosure can be applied to a variety of products. For example, the eNodeB100 can be implemented as an eNodeB800, which includes a main body (also referred to as a base station device) for controlling radio communications and an antenna. Alternatively, the eNodeB100 can be implemented as an eNodeB830, which includes a main body for controlling radio communications, one or more remote radio heads (RRHs) located at a different location from the main body, and an antenna.

[0389] Additionally, UE 200 can be implemented as, for example, a mobile terminal (such as a smartphone, tablet PC, laptop PC, portable game console, portable / don't mobile router, or digital camera) or as an in-vehicle terminal (such as a car navigation device). Furthermore, UE 200 can also be implemented as a terminal performing machine-to-machine (M2M) communication (also referred to as a machine-type communication (MTC) terminal). Additionally, UE 200 can be a radio communication module (e.g., an integrated circuit module constructed on a single die) installed on these terminals.

[0390] <<5.1. Applications Related to eNodeB>>

[0391] (First Application)

[0392] Figure 38 This is a block diagram illustrating a first example of a schematic structure of an eNodeB to which the technology according to embodiments of the present disclosure can be applied. The eNodeB 800 includes one or more antennas 810 and a base station device 820. Each antenna 810 and base station device 820 can be connected to each other via RF cables.

[0393] Each antenna 810 includes one or more antenna elements (e.g., multiple antenna elements constituting a MIMO antenna) and is used by the base station device 820 to transmit and receive radio signals. Figure 38 As shown, the eNodeB 800 may include a plurality of antennas 810, and the plurality of antennas 810 may each correspond to, for example, a plurality of frequency bands used by the eNodeB 800. It should be noted that, although Figure 38 An example of an eNodeB 800 including multiple antennas 810 is shown, but an eNodeB 800 may also include a single antenna 810.

[0394] The base station device 820 is equipped with a controller 821, a memory 822, a network interface 823, and a radio communication interface 825.

[0395] The controller 821 may be, for example, a CPU or a DSP, and enables various high-level functions of the base station device 820. For example, the controller 821 generates data packets based on data in signals processed by the radio communication interface 825, and forwards the generated packets via the network interface 823. The controller 821 can also generate bundled packets by bundling data from multiple baseband processors, and forward the generated bundled packets. Additionally, the controller 821 may include logical functions for performing control (such as Radio Resource Control (RRC), Radio Bearer Control, Mobility Management, License Control, or Scheduling). Furthermore, this control can be performed in cooperation with nearby eNodeBs or core network nodes. The memory 822 includes RAM and ROM, and stores programs executed by the controller 821, as well as various control data (such as, for example, terminal lists, transmit power data, and scheduling data).

[0396] Network interface 823 is a communication interface for connecting base station device 820 to core network 824. Controller 821 can also communicate with core network node or another eNodeB via network interface 823. In this case, eNodeB 800 and core network node or other eNodeBs can be connected to each other via a logical interface (e.g., S1 interface or X2 interface). Network interface 823 can also be a wired communication interface or a wireless communication interface for wireless backhaul. When network interface 823 is a wireless communication interface, it can use a higher frequency band than that used by radio communication interface 825 for wireless communication.

[0397] The radio communication interface 825 supports cellular communication schemes such as LTE or LTE-Advanced and provides radio connectivity with terminals located within the cell of the eNodeB 800 via antenna 810. Typically, the radio communication interface 825 may include a baseband (BB) processor 826, RF circuitry 827, etc. For example, the BB processor 826 may perform processing such as encoding / decoding, modulation / demodulation, and multiplexing / demultiplexing, and perform various signal processing at each layer (e.g., L1, Media Access Control (MAC), Radio Link Control (RLC), and Packet Data Convergence Protocol (PDCP)). The BB processor 826 may also replace the controller 821, including some or all of the logic functions discussed above. The BB processor 826 may be a module including a memory storing communication control programs, a processor executing such programs, and related circuitry. The functionality of the BB processor 826 can also be modified by updating the program. Furthermore, the module may be a card or chip inserted into a slot in the base station device 820 or a chip mounted on said card or chip. Meanwhile, the RF circuit 827 may include components such as mixers, filters, and amplifiers, and transmits or receives radio signals via antenna 810.

[0398] like Figure 38 As shown, the radio communication interface 825 may also include a plurality of BB processors 826, and the plurality of BB processors 826 may each correspond to a plurality of frequency bands, for example, used by the eNodeB 800. Additionally, as... Figure 38 As shown, the radio communication interface 825 may also include multiple RF circuits 827, and for example, the multiple RF circuits 827 may each correspond to multiple antenna elements. It should be noted that, although... Figure 38 An example of a radio communication interface 825 is shown, which includes multiple BB processors 826 and multiple RF circuits 827, but the radio communication interface 825 may also include a single BB processor 826 or a single RF circuit 827.

[0399] (Second Application)

[0400] Figure 39 This is a block diagram illustrating a second example of an eNodeB structure to which the technology according to embodiments of the present disclosure can be applied. The eNodeB 830 includes one or more antennas 840, a base station device 850, and an RRH 860. The respective antennas 840 and RRH 860 can be connected to each other via RF cables. Furthermore, the base station device 850 and RRH 860 can be connected to each other via a high-speed link such as an optical fiber.

[0401] Each antenna 840 includes one or more antenna elements (e.g., multiple antenna elements constituting a MIMO antenna) and is used by the RRH 860 to transmit and receive radio signals. Figure 39 As shown, the eNodeB 830 may include a plurality of antennas 840, and the plurality of antennas 840 may each correspond to, for example, a plurality of frequency bands used by the eNodeB 830. It should be noted that, although Figure 39 An example of an eNodeB 830 including multiple antennas 840 is shown, but an eNodeB 830 may also include a single antenna 840.

[0402] The base station device 850 is equipped with a controller 851, a memory 852, a network interface 853, a radio communication interface 855, and a connection interface 857. The controller 851, memory 852, and network interface 853 are similar to those in reference [reference missing]. Figure 38 The controller 821, memory 822, and network interface 823 are described.

[0403] The radio communication interface 855 supports cellular communication schemes (such as LTE or LTE-Advanced) and provides radio connectivity to terminals located in the sector corresponding to the RRH 860 via the RRH 860 and antenna 840. Typically, the radio communication interface 855 may include a BB processor 856, etc. Except for the RF circuitry 864 connected to the RRH 860 via the connection interface 857, the BB processor 856 is similar to the reference... Figure 38 The BB processor 826 is described. (e.g.) Figure 39 As shown, the radio communication interface 855 may also include a plurality of BB processors 856, and the plurality of BB processors 856 may each correspond to a plurality of frequency bands, for example, used by the eNodeB 830. It should be noted that, although Figure 39 An example of a radio communication interface 855 including multiple BB processors 856 is shown, but the radio communication interface 855 may also include a single BB processor 856.

[0404] Connection interface 857 is an interface for connecting base station device 850 (radio communication interface 855) to RRH 860. Connection interface 857 can also be a communication module for connecting base station device 850 (radio communication interface 855) and RRH 860 on a high-speed link.

[0405] In addition, the RRH 860 is equipped with a connection interface 861 and a radio communication interface 863.

[0406] Connection interface 861 is an interface for connecting RRH 860 (radio communication interface 863) to base station device 850. Connection interface 861 can also be a communication module for communication on a high-speed link.

[0407] Radio communication interface 863 transmits and receives radio signals via antenna 840. Typically, radio communication interface 863 may include RF circuitry 864. RF circuitry 864 may include components such as mixers, filters, and amplifiers, and transmits or receives radio signals via antenna 840. Figure 39 As shown, the radio communication interface 863 may also include multiple RF circuits 864, and for example, the multiple RF circuits 864 may each correspond to multiple antenna elements. It should be noted that, although... Figure 39 An example of a radio communication interface 863 including multiple RF circuits 864 is shown, but the radio communication interface 863 may also include a single RF circuit 864.

[0408] exist Figure 38 and 39 In the eNodeB 800 and eNodeB 830 shown, refer to Figure 21 The control unit 150 described and referenced Figure 31 The described control unit 151 may be implemented in radio communication interface 825, radio communication interface 855, and / or radio communication interface 863. Furthermore, at least some of these functions may also be implemented in controller 821 and controller 851.

[0409] <<5.2. Applications Related to UE>>

[0410] (First Application)

[0411] Figure 40 This is a block diagram illustrating an example of a schematic structure of a smartphone 900 to which the technology according to embodiments of the present disclosure can be applied. The smartphone 900 is equipped with a processor 901, a memory 902, a memory 903, an external connection interface 904, a camera 906, a sensor 907, a microphone 908, an input device 909, a display device 910, a speaker 911, a radio communication interface 912, one or more antenna switches 915, one or more antennas 916, a bus 917, a battery 918, and an auxiliary controller 919.

[0412] Processor 901 may be, for example, a CPU or a system-on-a-chip (SoC), and controls functions in the application layer and other layers of smartphone 900. Memory 902 includes RAM and ROM, and stores programs and data executed by processor 901. Memory 903 may include storage media such as semiconductor memory or hard disk. External connection interface 904 is an interface for connecting externally connected devices (such as memory cards or Universal Serial Bus (USB) devices) to smartphone 900.

[0413] Camera 906 includes an image sensor (such as a charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) sensor) and produces captured images. Sensor 907 may include, for example, a sensor array, such as a positioning sensor, a gyroscope sensor, a geomagnetic sensor, and an accelerometer. Microphone 908 converts audio input to smartphone 900 into audio signals. Input device 909 includes means such as touch sensors, keys, keyboards, buttons, or switches for detecting touches on the screen of display device 910, and receives operations or information input from the user. Display device 910 includes a screen (such as a liquid crystal display (LCD) or organic light-emitting diode (OLED) display) and displays the output image of smartphone 900. Speaker 911 converts the audio signals output from smartphone 900 into audio.

[0414] The radio communication interface 912 supports cellular communication schemes (such as LTE or LTE-Advanced) and performs radio communication. Typically, the radio communication interface 912 may include a BB processor 913, RF circuitry 914, etc. For example, the BB processor 913 may perform processes such as encoding / decoding, modulation / demodulation, and multiplexing / demultiplexing, and perform various signal processing for radio communication. Meanwhile, the RF circuitry 914 may include components such as mixers, filters, and amplifiers, and transmits or receives radio signals via antenna 916. The radio communication interface 912 may also be a single-chip module integrating the BB processor 913 and RF circuitry 914. The radio communication interface 912 may also include multiple BB processors 913 and multiple RF circuits 914, such as... Figure 40 As shown in the image. It should be noted that, although... Figure 40 An example of a radio communication interface 912 including multiple BB processors 913 and multiple RF circuits 914 is shown, but the radio communication interface 912 may also include a single BB processor 913 or a single RF circuit 914.

[0415] In addition to cellular communication schemes, the radio communication interface 912 can also support other types of radio communication schemes, such as short-range wireless communication schemes, near-field wireless communication schemes, or wireless local area network (LAN) schemes. In this case, a BB processor 913 and an RF circuit 914 can be included for each radio communication scheme.

[0416] Each antenna switch 915 switches the destination of antenna 916 among multiple circuits (e.g., circuits for different radio communication schemes) included in the radio communication interface 912.

[0417] Each antenna 916 includes one or more antenna elements (e.g., multiple antenna elements constituting a MIMO antenna) and is used by a radio communication interface 912 to transmit and receive radio signals. The smartphone 900 may also include multiple antennas 916, such as... Figure 40 As shown in the image. It should be noted that, although... Figure 40 An example of a smartphone 900 including multiple antennas 916 is shown, but the smartphone 900 may also include a single antenna 916.

[0418] Additionally, the smartphone 900 may be equipped with an antenna 916 for each radio communication scheme. In this case, the antenna switch 915 can be omitted from the structure of the smartphone 900.

[0419] Bus 917 interconnects processor 901, memory 902, memory 903, external connection interface 904, camera 906, sensor 907, microphone 908, input device 909, display device 910, speaker 911, radio communication interface 912, and auxiliary controller 919. Battery 918 provides power via power lines shown in dashed lines in the accompanying drawings. Figure 40 The various blocks of the smartphone 900 are shown. For example, the auxiliary controller 919 enables the smartphone 900 to operate with minimal functionality while in sleep mode.

[0420] exist Figure 40 Among the smartphones shown in the image 900, refer to... Figure 22 The control unit 240 described and the reference Figure 33 The described control unit 241 can be implemented in the radio communication interface 912. Additionally, at least some of these functions can be implemented in the processor 901 or the auxiliary controller 919.

[0421] (Second Application)

[0422] Figure 41 This is a block diagram illustrating an example of a schematic structure of a car navigation device 920 to which the technology according to embodiments of the present disclosure can be applied. The car navigation device 920 is equipped with a processor 921, a memory 922, a Global Positioning System (GPS) module 924, a sensor 925, a data interface 926, a content player 927, a storage medium interface 928, an input device 929, a display device 930, a speaker 931, a radio communication interface 933, one or more antenna switches 936, one or more antennas 937, and a battery 938.

[0423] The processor 921 may be, for example, a CPU or a SoC, and controls the car navigation function and other functions of the car navigation device 920. The memory 922 includes RAM and ROM, and stores programs and data executed by the processor 921.

[0424] GPS module 924 measures the position (e.g., latitude, longitude, and altitude) of vehicle navigation device 920 using GPS signals received from GPS satellites. Sensor 925 may include, for example, a sensor array such as a gyroscope sensor, a geomagnetic sensor, and a barometric pressure sensor. Data interface 926 is connected to vehicle network 941 via a port not shown in the figure and acquires data generated on the vehicle side, such as vehicle speed data.

[0425] Content player 927 plays content stored on a storage medium (e.g., CD or DVD) inserted into storage medium interface 928. Input device 929 includes means such as a touch sensor, button, or switch for detecting touch on the screen of display device 930, and receives operations or information input from the user. Display device 930 includes a screen such as an LCD or OLED display and displays images of navigation functions or playback content. Speaker 931 outputs audio of navigation functions or playback content.

[0426] The radio communication interface 933 supports cellular communication schemes (such as LTE or LTE-Advanced) and performs radio communication. Typically, the radio communication interface 933 may include a BB processor 934, RF circuitry 935, etc. For example, the BB processor 934 may perform processes such as encoding / decoding, modulation / demodulation, and multiplexing / demultiplexing, and perform various signal processing for radio communication. Meanwhile, the RF circuitry 935 may include components such as mixers, filters, and amplifiers, and transmits or receives radio signals via antenna 937. The radio communication interface 933 may also be a single-chip module integrating the BB processor 934 and RF circuitry 935. The radio communication interface 933 may also include multiple BB processors 934 and multiple RF circuits 935, such as... Figure 41 As shown in the image. It should be noted that, although... Figure 41 An example of a radio communication interface 933 is shown, which includes multiple BB processors 934 and multiple RF circuits 935, but the radio communication interface 933 may also include a single BB processor 934 or a single RF circuit 935.

[0427] In addition to cellular communication schemes, the radio communication interface 933 can also support other types of radio communication schemes (such as short-range wireless communication schemes, near-field wireless communication schemes, or wireless LAN schemes). In this case, a BB processor 934 and an RF circuit 935 can be included for each radio communication scheme.

[0428] Each antenna switch 936 switches the destination of antenna 937 among multiple circuits (e.g., circuits for different radio communication schemes) included in the radio communication interface 933.

[0429] Each antenna 937 includes one or more antenna elements (e.g., multiple antenna elements constituting a MIMO antenna) and is used by a radio communication interface 933 to transmit and receive radio signals. The car navigation device 920 may also include multiple antennas 937, such as... Figure 41 As shown in the image. It should be noted that, although... Figure 41 An example of a car navigation device 920 including multiple antennas 937 is shown, but the car navigation device 920 may also include a single antenna 937.

[0430] Additionally, the car navigation device 920 may also be equipped with an antenna 937 for each radio communication scheme. In this case, the antenna switch 936 can be omitted from the structure of the car navigation device 920.

[0431] Battery 938 supplies power via the power lines shown in the accompanying drawings, partially indicated by dashed lines. Figure 41 The various blocks of the car navigation device 920 are shown in the diagram. Additionally, the battery 938 stores power supplied from the vehicle.

[0432] exist Figure 41 In the car navigation device 920 shown, refer to Figure 22 The control unit 240 described and the reference Figure 33 The described control unit 241 can be implemented in the radio communication interface 933. Furthermore, at least some of these functions can also be implemented in the processor 921.

[0433] Additionally, the technology according to this disclosure can also be implemented as an in-vehicle system (or vehicle) 940 including one or more blocks of the car navigation device 920 discussed above, an in-vehicle network 941, and a vehicle-side module 942. The vehicle-side module 942 generates vehicle-side data (such as vehicle speed, engine speed, or fault information) and outputs the generated data to the in-vehicle network 941.

[0434] <<<6. Conclusion>>>

[0435] The above has been referred to Figures 1 to 37 This disclosure describes a communication apparatus and process according to embodiments thereof. In a first embodiment of this disclosure, synchronization relationship information indicating which frequency bands among a plurality of CCs used for radio communication are synchronized with each other is acquired. Then, the synchronization relationship information is controlled to be sent to the UE 200.

[0436] This reduces the load on UE 200 during carrier aggregation. In other words, when synchronization relationship information is sent from eNodeB 100 to UE 200, UE 200 does not need to individually verify which CC is synchronized with which CC. For example, when mutually synchronized CCs exist (e.g., legacy CCs and SNCT, UNCTs and UNCTs), UE 200 can use information about the synchronization status of UE 200 in one CC for the other CC. In this way, the load on UE 200 is reduced.

[0437] For example, the plurality of CCs includes one or more different CCs used to transmit CRS in each subframe. Synchronization relationship information at least indicates which of the one or more frequency bands is synchronized with which of the one or more frequency bands.

[0438] For example, the one or more CCs include one or more synchronization bands that are synchronized with any one of the one or more different frequency bands. Synchronization relationship information at least indicates which of the one or more synchronization bands is synchronized with which of the one or more different frequency bands.

[0439] Therefore, UE 200 does not need to check which legacy CC is synchronized with the SNCT individually. For example, UE 200 can use information about the synchronization status of the legacy CC synchronized with the SNCT in the SNCT. In this way, the load on UE 200 can be reduced.

[0440] For example, synchronization information at least indicates which frequency bands are synchronized with each other among the one or more frequency bands.

[0441] For example, the plurality of CCs includes one or more different CCs used to transmit CRS in each subframe. The one or more CCs include two or more asynchronous frequency bands that are not synchronized with any of the one or more different frequency bands. Synchronization relationship information at least indicates which of the two or more asynchronous frequency bands are synchronized with each other.

[0442] Therefore, UE 200 does not need to check which UNCT is synchronized with which UNCT separately. For example, UE 200 can use information about the synchronization status of one UNCT for another UNCT synchronized with that UNCT. In this way, the load on UE 200-1 can be reduced.

[0443] Each of the plurality of CCs may be a CC that was not used to transmit CRS in at least one subframe.

[0444] Therefore, UE 200-1 does not need to individually verify which NCT is synchronized with which NCT. For example, UE 200-1 can use information about the synchronization status of one NCT for another NCT synchronized with that NCT. In this way, the load on UE 200-1 can be reduced.

[0445] For example, in a first variant of the first embodiment, the one or more CCs not used to transmit CRS in at least one subframe include two or more mutually synchronized CCs. CRS is transmitted using some of the two or more CCs in at least one subframe, and the remaining CCs are not used.

[0446] Thus, radio resources can be used efficiently. In other words, the radio resources used to transmit control signals can be reduced.

[0447] For example, in a first variant of the first embodiment, the one or more CCs not used to transmit CRS in at least one subframe include two or more mutually synchronized CCs. UE 200-1 monitors the synchronization status of UE 200 in some of the two or more CCs, and does not monitor the synchronization status of UE 200 in the remaining two or more CCs.

[0448] Therefore, when there are mutually synchronized NCTs and UE 200 monitors the synchronization status of UE 200 in some NCTs, UE 200 does not need to monitor the synchronization status of UE 200 in the remaining CCs. In this way, the load on UE 200 can be reduced.

[0449] In a second embodiment of this disclosure, the plurality of CCs used for radio communication include two or more CCs that are not used to transmit CRS in at least one subframe. At least two of the two or more CCs transmit CRS at mutually different frequencies.

[0450] In this way, when there are NCTs used to transmit CRS at different frequencies, UE 200 can selectively use the NCT according to the environment. For example, UE 200 in an environment with low SNR uses the NCT used to transmit CRS at a higher frequency. UE 300 in an environment with high SNR uses the NCT used to transmit CRS at a lower frequency. As a result, UE 200 can obtain its own synchronization state. In addition, the overhead caused by CRS can be reduced.

[0451] For example, synchronization capability determination information is acquired to determine whether UE 200 can synchronize in each of the two or more frequency bands that are not used to transmit CRS in at least one subframe. The control sends the synchronization capability determination information to UE 200-2.

[0452] When this information is provided, even though the transmission frequency of CRS varies due to NCT, UE 200 is able to know which NCT is required to achieve the synchronization state. Therefore, UE 200 can more reliably achieve the synchronization state without using trial and error by selecting and using the appropriate NCT based on the environment (that is, establishing a connection with eNodeB 100-1 in the appropriate NCT).

[0453] For example, synchronization capability determination information includes information about the transmission frequency of CRS in each of the two or more CCs that were not used to transmit CRS in at least one subframe.

[0454] When this information is provided, UE 200 is able to know the transmission frequency of the CRS in each NCT. Therefore, UE 200 can more reliably achieve synchronization without using trial and error by selecting an appropriate CRS transmission frequency based on the environment and using the CRS associated with that transmission frequency.

[0455] Synchronization capability determination information may include information about the recommended communication quality for each of the two or more CCs that were not used to transmit CRS in at least one subframe.

[0456] When this information is provided, UE 200 is able to determine the level of communication quality (e.g., SNR) required to achieve a synchronized state in each NCT. Therefore, UE 200 can more reliably achieve a synchronized state without using trial and error by selecting an appropriate NCT based on the actual SNR in each NCT and using that NCT.

[0457] Synchronization capability determination information may include information about the power control of each of the two or more CCs that were not used to transmit CRS in at least one subframe.

[0458] When this information is provided, UE 200 is able to know which NCT is needed to more easily achieve a synchronized state. Therefore, UE 200 can more reliably achieve a synchronized state without using trial and error by selecting and using the appropriate NCT.

[0459] For example, in a first variant of the second embodiment, the two or more CCs not used to transmit CRS in at least one subframe include a low-frequency CC used to transmit CRS at a first frequency along the time direction and a high-frequency CC used to transmit CRS at a second frequency higher than the first frequency along the time direction. The control unit 151 controls the transmission such that some or all of the subframes using the low-frequency CC to transmit CRS become subframes using the high-frequency CC to transmit CRS.

[0460] Therefore, by reducing the operating time of UE 200, it is possible to prevent an increase in the power consumption of UE 200.

[0461] For example, in a second variation of the second embodiment, CRS is transmitted at different frequencies in at least two or more mutually synchronized CCs among the two or more CCs that are not used to transmit the common reference signal in at least one subframe.

[0462] Because UE 200 can more reliably achieve synchronization in one of the mutually synchronized NCTs through CRS transmission, NCTs can be used more reliably. For example, even in environments with poor communication quality, UE 200 can achieve synchronization in an NCT associated with a higher CRS transmission frequency. UE 200 can then use information about the synchronization state in another NCT.

[0463] Preferred embodiments of the present disclosure have been described above with reference to the accompanying drawings, but the present disclosure is by no means limited to the examples described above. Various changes and modifications will be apparent to those skilled in the art within the scope of the appended claims, and it should be understood that they will naturally fall within the technical scope of this disclosure.

[0464] For example, an example has been described where the multiple frequency bands (CCs) used for radio communication are used by a single base station (eNodeB), but embodiments of this disclosure are not limited thereto. For example, each of the multiple frequency bands used for radio communication may be used by any one of the multiple base stations. For example, each of the multiple frequency bands may be used by any one of the base stations of a macro cell and any base station of a small cell that partially or completely overlaps with the macro cell. In this case, the frequency bands used by different base stations may be used simultaneously by a terminal device (e.g., a UE). That is, carrier aggregation reaching multiple base stations can be performed.

[0465] In the second embodiment, an example of a terminal device (UE) using multiple frequency bands simultaneously has been described, but the embodiments of this disclosure are not limited thereto. In the case described in the second embodiment, the terminal device may use any one of the multiple frequency bands. That is, the terminal device may not support carrier aggregation.

[0466] The fact that frequency bands are far apart has been described as a reason for frequency bands not being synchronized with each other, but this is not the only reason. For example, another reason is that frequency bands may not be synchronized with each other. For instance, in some cases, some frequency bands can be used by a certain base station (e.g., a macro cell base station). The remaining frequency bands can be used by another base station (e.g., a small cell base station). In this case, there is a possibility that the frequency band used by the one base station is not synchronized with the frequency band used by the other base station.

[0467] Examples of radio communication systems conforming to a range of LTE communication standards have been described, but embodiments of this disclosure are not limited to these examples. For instance, the radio communication system may be a system conforming to other communication standards. In this case, instead of an eNodeB, the base station included in the radio communication system may be implemented as different types of base stations, such as a NodeB or a Base Transceiver Station (BTS). Instead of a UE, the terminal device included in the radio communication system may be implemented as different types of terminal devices, such as a Mobile Station (MS).

[0468] Furthermore, the processing steps in the communication control process described in this specification are not strictly limited to being executed in the chronological order that conforms to the order depicted in the flowchart. For example, the processing steps in the communication control process may be executed in a different order than that described herein as a flowchart, and may also be executed in parallel.

[0469] Additionally, computer programs can be created to enable hardware (such as CPU, ROM, and RAM) built into a communication control device or terminal device to function similarly to each structural element of the aforementioned communication control device or terminal device.

[0470] Alternatively, this technology can also be constructed as follows.

[0471] (1) A communication control device, comprising:

[0472] The acquisition unit is configured to acquire synchronization relationship information indicating which frequency bands among multiple frequency bands used for radio communication are synchronized with each other; and

[0473] The control unit is configured to control the transmission of the synchronization relationship information to the terminal device.

[0474] The plurality of frequency bands include one or more frequency bands that are not used to transmit a common reference signal in at least one subframe, which is a unit of time in radio communication.

[0475] (2) The communication control apparatus as described in (1), wherein the plurality of frequency bands includes one or more different frequency bands used to transmit a common reference signal in each subframe, and

[0476] The synchronization relationship information indicates at least which of the one or more frequency bands is synchronized with which of the one or more different frequency bands.

[0477] (3) The communication control device as described in (2), wherein the one or more frequency bands include one or more synchronization frequency bands synchronized with one of the one or more different frequency bands, and

[0478] The synchronization relationship information indicates at least which of the one or more synchronization frequency bands is synchronized with which of the one or more different frequency bands.

[0479] (4) The communication control device as described in any one of (1) to (3), wherein the synchronization relationship information indicates at least which of the one or more frequency bands are synchronized with each other.

[0480] (5) The communication control apparatus as described in (4), wherein the plurality of frequency bands includes one or more different frequency bands used to transmit a common reference signal in each subframe, and

[0481] The one or more frequency bands mentioned above include two or more asynchronous frequency bands that are not synchronized with the one or more different frequency bands, and

[0482] The synchronization relationship information indicates at least which frequency bands among the two or more asynchronous frequency bands are synchronized with each other.

[0483] (6) The communication control device as described in (4), wherein each of the plurality of frequency bands is a frequency band that is not used to transmit a common reference signal in at least one subframe within a subframe.

[0484] (7) The communication control device as described in (1), wherein the one or more frequency bands include two or more frequency bands that are synchronized with each other, and

[0485] In at least one subframe, a common reference signal is transmitted using some of the two or more frequency bands, and in all subframes, the remaining frequency bands of the two or more frequency bands are not used to transmit the common reference signal.

[0486] (8) The communication control device as described in (1), wherein the one or more frequency bands include two or more frequency bands that are synchronized with each other, and

[0487] The terminal device monitors the synchronization status of terminal devices in some of the two or more frequency bands, but does not monitor the synchronization status of terminal devices in the remaining frequency bands.

[0488] (9) The communication control device as described in (1), wherein the control unit controls the transmission of signals utilizing the plurality of frequency bands.

[0489] The plurality of frequency bands includes two or more frequency bands that are not used to transmit a common reference signal in at least one subframe, which is a unit of time in radio communication, and

[0490] The control unit controls the transmission in such a way that it transmits a common reference signal at different frequencies using at least two of the two or more frequency bands.

[0491] (10) The communication control device as described in (9), wherein the two or more frequency bands include a low-frequency frequency band for transmitting a common reference signal at a first frequency along the time direction and a high-frequency frequency band for transmitting a common reference signal at a second frequency higher than the first frequency along the time direction, and

[0492] The control unit controls the transmission in such a way that some or all of the subframes that transmit the common reference signal using a low-frequency band are subframes that transmit the common reference signal using a high-frequency band.

[0493] (11) The communication control device as described in (9), wherein the acquisition unit acquires synchronization capability determination information for determining whether the terminal device is capable of synchronizing in each of the two or more frequency bands, and

[0494] The control unit controls the sending of synchronization capability determination information to the terminal device.

[0495] (12) The communication control device as described in (11), wherein the synchronization capability determination information includes information about the transmission frequency of a common reference signal in each of the two or more frequency bands.

[0496] (13) The communication control device as described in (11) or (12), wherein the synchronization capability determination information includes information about the recommended communication quality in each of the two or more frequency bands.

[0497] (14) The communication control device as described in any one of (11) to (13), wherein the synchronization capability determination information includes information regarding power control for each of the two or more frequency bands.

[0498] (15) A communication control device as described in any of (9) to (14), wherein the control unit controls the transmission in such a way that a common reference signal is transmitted at different frequencies in at least two mutually synchronized frequency bands of the two or more frequency bands.

[0499] (16) A program that enables a computer to function as:

[0500] The acquisition unit is configured to acquire synchronization relationship information indicating which frequency bands among multiple frequency bands used for radio communication are synchronized with each other; and

[0501] The control unit is configured to control the transmission of synchronization relationship information to the terminal device.

[0502] The plurality of frequency bands include one or more frequency bands that are not used to transmit a common reference signal in at least one subframe, which is a unit of time in radio communication.

[0503] (17) A communication control method, comprising:

[0504] Acquire synchronization relationship information indicating which frequency bands are synchronized with each other among multiple frequency bands used for radio communication; and

[0505] The control system sends synchronization relationship information to the terminal device.

[0506] The plurality of frequency bands include one or more frequency bands that are not used to transmit a common reference signal in at least one subframe, which is a unit of time in radio communication.

[0507] (18) A terminal device, comprising:

[0508] The acquisition unit is configured to acquire the synchronization relationship information when it receives synchronization relationship information indicating which frequency bands among a plurality of frequency bands used for radio communication are synchronized with each other;

[0509] The control unit is configured to perform control based on synchronization relationship information for the purpose of synchronization across the multiple frequency bands.

[0510] The plurality of frequency bands include one or more frequency bands that are not used to transmit a common reference signal in at least one subframe, which is a unit of time in radio communication.

[0511] (19) A communication control device, comprising:

[0512] The control unit is configured to control the transmission of signals in multiple frequency bands used for radio communication.

[0513] The plurality of frequency bands includes two or more frequency bands that are not used to transmit a common reference signal in at least one subframe, which is a unit of time in radio communication, and

[0514] The control unit controls the transmission in such a way that it transmits a common reference signal at different frequencies using at least two of the two or more frequency bands.

[0515] (20) A terminal device, comprising:

[0516] The control unit is configured to select, from a plurality of frequency bands used for radio communication, the frequency band for radio communication of the terminal device.

[0517] The plurality of frequency bands includes two or more frequency bands that are not used to transmit a common reference signal in at least one subframe, which is a unit of time in radio communication, and

[0518] A common reference signal is transmitted at different frequencies using at least two of the two or more frequency bands.

[0519] List of reference numerals

[0520] 10 communities

[0521] 30-component carrier (CC)

[0522] 100eNodeB

[0523] 110 antenna elements

[0524] 120 radio communication unit

[0525] 130 Network Communication Unit

[0526] Storage units 140 and 141

[0527] 150, 151 control units

[0528] 200 User Equipment (UE)

[0529] 210 antenna elements

[0530] 220 radio communication unit

[0531] Storage units 230 and 231

[0532] Control units 240 and 241

Claims

1. A communication control device, comprising: At least one processor is configured as follows: The system sends synchronization relationship information to the terminal, indicating which frequency bands among multiple frequency bands used for radio communication are synchronized with each other, so that the terminal synchronizes the multiple frequency bands based on the synchronization relationship information. Signals are transmitted using the plurality of frequency bands, wherein the plurality of frequency bands includes at least two frequency bands that are not used to transmit a common reference signal in at least one of a plurality of subframes that are units of time in radio communication, and A common reference signal is transmitted at different intervals using at least two of the multiple frequency bands.

2. The communication control device as described in claim 1, The at least two frequency bands include a low-frequency band for transmitting a common reference signal at a first frequency along the time direction and a high-frequency band for transmitting the common reference signal at a second frequency higher than the first frequency along the time direction. Some or all of the subframes that use low-frequency bands to transmit common reference signals are subframes that use high-frequency bands to transmit common reference signals.

3. The communication control device as claimed in claim 1, wherein the at least one processor is further configured to: Acquire synchronization capability determination information to determine whether the terminal device is capable of synchronization in each of the at least two frequency bands, and The synchronization capability determination information is sent to the terminal device.

4. The communication control device of claim 3, wherein the synchronization capability determination information includes information about the transmission frequency of a common reference signal in each of the at least two frequency bands.

5. The communication control device of claim 3, wherein the synchronization capability determination information includes information regarding the recommended communication quality in each of the at least two frequency bands.

6. The communication control apparatus of claim 3, wherein the synchronization capability determination information includes information regarding power control for each of the at least two frequency bands.

7. The communication control apparatus of claim 1, wherein a common reference signal is transmitted at different intervals in at least two mutually synchronized frequency bands.

8. A communication control method, comprising: The system sends synchronization relationship information to the terminal, indicating which frequency bands among multiple frequency bands used for radio communication are synchronized with each other, so that the terminal synchronizes the multiple frequency bands based on the synchronization relationship information. Signals are transmitted using the plurality of frequency bands, wherein the plurality of frequency bands includes at least two frequency bands that are not used to transmit a common reference signal in at least one of a plurality of subframes that are units of time in radio communication, and A common reference signal is transmitted at different intervals using at least two of the multiple frequency bands.

9. The communication control method as described in claim 8, The at least two frequency bands include a low-frequency band for transmitting a common reference signal at a first frequency along the time direction and a high-frequency band for transmitting the common reference signal at a second frequency higher than the first frequency along the time direction. Some or all of the subframes that use low-frequency bands to transmit common reference signals are subframes that use high-frequency bands to transmit common reference signals.

10. The communication control method as described in claim 8, further comprising: Acquire synchronization capability determination information to determine whether the terminal device is capable of synchronization in each of the at least two frequency bands, and The synchronization capability determination information is sent to the terminal device.

11. The communication control method of claim 10, wherein the synchronization capability determination information includes information about the transmission frequency of a common reference signal in each of the at least two frequency bands.

12. The communication control method of claim 10, wherein the synchronization capability determination information includes information about the recommended communication quality in each of the at least two frequency bands.

13. The communication control method of claim 10, wherein the synchronization capability determination information includes information regarding power control for each of the at least two frequency bands.

14. The communication control method of claim 8, wherein a common reference signal is transmitted at different intervals in at least two mutually synchronized frequency bands.

15. A terminal device, comprising: At least one processor is configured as follows: Receive synchronization relationship information indicating which frequency bands among multiple frequency bands used for radio communication are synchronized with each other; The multiple frequency bands are synchronized based on synchronization relationship information; Signals are received using the plurality of frequency bands, wherein the plurality of frequency bands include at least two frequency bands that are not used to transmit a common reference signal in at least one of a plurality of subframes that are units of time in radio communication; and A common reference signal is received using at least two of the multiple frequency bands at different intervals.

16. A method for a terminal device, comprising: Receive synchronization relationship information indicating which frequency bands among multiple frequency bands used for radio communication are synchronized with each other; The multiple frequency bands are synchronized based on synchronization relationship information; Signals are received using the plurality of frequency bands, wherein the plurality of frequency bands include at least two frequency bands that are not used to transmit a common reference signal in at least one of a plurality of subframes that are units of time in radio communication; and A common reference signal is received using at least two of the multiple frequency bands at different intervals.

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