Terminal device, control method, and program for achieving power saving in communication systems

Abstract

This invention provides a base station device, terminal device, control method, and program for efficiently operating a power-saving function that involves stopping the transmission of the Synchronization Signal / Physical Broadcast Channel block (SSB) and System Information Block Type 1 (SIB1). [Solution] In a wireless communication network in which communication services are provided to terminal devices using at least one of a plurality of cells, if the transmission of system information is stopped in the first cell (low-power cell) among the plurality of cells, the first base station device notifies terminal devices located in the cell provided by the first base station device of information regarding the second cell (anchor cell) to which the system information that has been stopped from being transmitted in the first cell (low-power cell) is transmitted.

Description

Technical Field

[0001] The present invention relates to a control technique for realizing wireless communication with low power consumption.

Background Art

[0002] In the 3rd Generation Partnership Project (3GPP (registered trademark)), suppressing the power consumption of the network has been discussed as an important issue. In Non-Patent Document 1, it has been proposed to stop the transmission of at least a part of the Synchronization Signal / Physical Broadcast Channel block (SSB) and System Information Block Type1 (SIB1), which are always transmitted for each component carrier (CC), in some CCs to achieve power saving. In Non-Patent Document 1, it has been proposed that information for connecting to a CC in which the transmission of at least a part of SSB and SIB1 is stopped is transmitted in other CCs. Throughout this embodiment, "CC" may be read as "cell".

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The operation method of the power saving function as described above is not clear at present, and a technique for efficiently operating this is required.

Means for Solving the Problems

[0005] The present invention provides a technique for efficiently operating a power saving function by stopping the transmission of SSB and SIB1 in some cells.

[0007] A terminal device according to one aspect of the present invention is a terminal device in a wireless communication network to which communication services are provided using at least one of a plurality of cells, For each adjacent cell to the cell in which the terminal device is located, the terminal device acquires configuration information for receiving system information that is transmitted upon request for power saving purposes. do acquisition means and When the power saving function in a base station device that provides power-saving cells stops, it receives updated configuration information corresponding to the cessation of the power saving function. do Received It has means and, [Effects of the Invention]

[0008] According to the present invention, the power saving function by stopping SSB and SIB1 transmission can be operated efficiently. [Brief explanation of the drawing]

[0009] [Figure 1] This diagram shows an example of a wireless communication network configuration. [Figure 2] This figure shows an example of information that is notified to a terminal device. [Figure 3] This figure shows an example of the device's hardware configuration. [Figure 4] This figure shows an example of the functional configuration of a base station device. [Figure 5] This figure shows an example of the functional configuration of a terminal device. [Figure 6] This diagram shows an example of the processing flow performed in a wireless communication network. [Figure 7] This diagram shows an example of the processing flow performed in a wireless communication network. [Modes for carrying out the invention]

[0010] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more of the features described in the embodiments may be combined in any way. Furthermore, identical or similar configurations will be given the same reference numeral, and redundant descriptions will be omitted.

[0011] (Network configuration) Figure 1 shows an example of the configuration of a wireless communication network according to this embodiment. This wireless communication network is, for example, a cellular communication system compliant with the cellular communication standard of the Third Generation Partnership Project (3GPP®). The wireless communication network is composed of, for example, base station devices 101 to 103 and a terminal device 121, and any of the multiple base station devices establish a connection with the terminal device 121 to provide wireless communication services. Here, for example, base station device 101 provides the first cell 111, base station device 102 provides the second cell 112, and base station device 103 provides the third cell 113. Here, "cell" may be read as component carrier (CC). Here, the first cell 111 to the third cell 113 may be provided using different frequencies (CC), or they may be provided using the same CC. In Figure 1, for the sake of simplicity, only three base station devices and one terminal device are shown, but of course there can be many more base station devices and terminal devices. Furthermore, a single base station device may provide multiple cells (multiple CCs). Alternatively, a single base station device may provide multiple cells (CCs) using radio transceivers located at different positions. Multiple base station devices may be configured to communicate with each other for the exchange of control information via, for example, an Xn interface or an S1 interface.

[0012] Conventionally, base station devices 101 to 103 are configured to transmit a Synchronization Signal / Physical Broadcast Channel block (SSB) and System Information Block Type 1 (SIB1) in each of the multiple cells (CCs). That is, SSB and SIB1 are transmitted periodically in each cell. Therefore, base station devices 101 to 103 consume power to transmit the SSB and SIB1.

[0013] In contrast, as described in Non-Patent Document 1, power consumption in the second cell can be reduced by transmitting connection information for the second cell (e.g., Master Information Block (MIB) and SIB1) in a first cell different from the second cell, without transmitting SSB or SIB1 in the second cell (CC). On the other hand, in this case, when the terminal device 121 searches for a connection destination in the second cell, since MIB and SIB1 are not transmitted in the second cell, if it only observes the wireless signal of this second cell, it cannot establish a connection or wait for a connection in the second cell. In other words, unless the terminal device 121 performs observation processing in the first cell where the MIB and SIB1 of the second cell are transmitted, it cannot acquire information about the second cell and therefore cannot establish a connection or wait for a connection in the second cell.

[0014] Here, for example, suppose that the base station device 102 has stopped transmitting system information such as MIB and SIB1 in the second cell 112. In this case, the terminal device 121 may have to observe radio signals transmitted in many cells in order to identify other cells that are transmitting MIB and SIB1 for the second cell 112. Therefore, if there are many cells available around the terminal device 121, it may take a long time for the terminal device 121 to acquire information about the second cell 112. For example, in Figure 1, if the terminal device 121 does not know whether the system information that has been stopped from being transmitted in the second cell 112 is being transmitted in the first cell 111 or the third cell 113, it needs to observe the radio signals sent from the base station device in each cell.

[0015] In this embodiment, in view of these circumstances, the terminal device 121 is notified of information regarding the cell in which system information that has been stopped from being transmitted in the second cell 112 is being transmitted in the cell where the terminal device 121 is located (camp on). For example, suppose the terminal device 121 is located in the first cell 111, and system information (MIB or SIB1) for the second cell 112 is being transmitted in the third cell 113. In this case, information is provided in the first cell 111 that enables the terminal device 121 to identify that system information for the second cell is being transmitted in the third cell 113. This information may include, for example, information indicating a cell that has a power-saving function that stops the transmission of system information. This information may be provided as information that associates information for identifying a cell, such as Physical Cell identity or Cell identity, with information indicating the presence or absence of a power-saving function. In the example shown in Figure 1, the identifier of the second cell 112 and information indicating that it has a power-saving function are associated and notified to the terminal device 121 from the first cell 111. This information may also include, for example, information indicating whether the power-saving function is enabled in the cell having such a power-saving function. For example, in one example, the first cell 111 may have a power-saving function, but it may not be enabled. In this case, information associating the identification information of the first cell 111, the fact that it has a power-saving function, and that the power-saving function is disabled may be notified from the first cell 111 to the terminal device 121.

[0016] Furthermore, this information includes information indicating the cell that provides system information when transmission is stopped due to a power-saving function. This information may be, for example, frequency information. In one example, system information for cells with the power-saving function enabled may be provided for all cells at a particular frequency, in which case information indicating that particular frequency may be provided as information indicating the cell that provides system information when transmission is stopped due to a power-saving function. In this case, identification information for the specific cell may not be included. For example, information on the frequency provided by the third cell 113 may be notified as information indicating the third cell 113 that provides system information when transmission is stopped in the second cell 112. The information indicating the frequency may be an ARFCN (Absolute Radio Frequency Channel Number). In addition to, or instead of, frequency information, identification information that identifies individual cells may be provided as information indicating the cell that provides system information when transmission is stopped. There may be multiple cells that provide system information when transmission is stopped, and in some cases only frequency information may be notified, while in other cases cell identification information may be notified. Furthermore, the third cell 113 may also provide the information notified by the first cell 111 as described above. That is, the third cell 113 is also notified that the second cell 112 has a power-saving function, that this function is enabled in the second cell 112, and that system information whose transmission has been stopped in the second cell 112 is provided in the third cell 113.

[0017] Figure 2 shows an example of the information provided. Hereinafter, a cell that provides system information for which transmission has been stopped may be referred to as an "anchor cell". In the example of Figure 2, the first cell 111 has a power saving function, but it is shown that the power saving function is not activated. Also, when the power saving function of the first cell 111 is activated and the transmission of system information is stopped, the system information is provided in the cell of ARFCN0. Here, the cell of ARFCN0 (not shown) provides system information when transmission is stopped in all cells included in the area where this information is provided. As the first anchor cell, only frequency information may be notified. For this reason, information for identifying a specific cell may not be included. Also, as the second anchor cell, the identification information of the third cell 113 of ARFCN1, for example, may be notified for the system information. In one example, it may be assumed that the cell of ARFCN1 does not provide system information for which transmission has been stopped in cells other than the third cell 113. In this case, cell identification information may be notified as anchor cell information. Note that only the cell identification information may be notified and frequency information may not be notified. Note that since the power saving function of the first cell 111 is not activated, the system information of the first cell 111 is transmitted in the first cell 111 and is not normally transmitted in the anchor cell. However, this is just an example, and even if the power saving function is not activated, system information may be provided in the anchor cell. Also, in the example of Figure 2, the second cell 112 has a power saving function, and it is shown that the power saving function is activated. And it is shown that the anchor cell of the second cell 112 is the same as the anchor cell of the first cell 111. Since the second cell 112 has the power saving function activated, system information is provided in the anchor cell. In the example of Figure 2, the third cell 113 is shown not to have a power saving function. For this reason, in the third cell 113, the power saving function is not activated, and there is no anchor cell setting either.

[0018] For example, in the first cell 111, information excluding the information related to the first cell 111 may be notified to the terminal device 121. Similarly, in the third cell 113, information excluding the information related to the third cell 113 may be notified to surrounding terminal devices. Of course, information including the information related to the first cell 111 may be notified in the first cell 111, and information including the information related to the third cell 113 may be notified in the third cell 113. Note that FIG. 2 shows only information related to three cells, but it is not limited thereto. That is, since the information notified to the terminal device in each cell includes information of cells around that cell (and information of that cell as necessary), when a large number of cells are present around, information related to those large number of cells will be notified. Note that the surrounding cells may be only adjacent cells, or may include cells other than adjacent cells within a certain distance range.

[0019] When the terminal device receives this information, for the second cell 112, when acquiring system information whose transmission is stopped, the terminal device acquires the information in the anchor cell. In one example, when the cell in which the terminal device is located is the anchor cell, the terminal device receives the information in that cell. On the other hand, when the cell in which the terminal device is not located is the anchor cell, the terminal device moves to the anchor cell and can receive the information in that anchor cell.

[0020] This section describes how a terminal device can acquire system information that has been disabled in other cells (hereinafter referred to as "power-saving cells") that have power-saving functions and whose power-saving functions are enabled, when the cell in which the terminal device is located is an anchor cell. For example, an anchor cell may periodically broadcast the disabled system information. In this case, the anchor cell may transmit the cell identifier of the power-saving cell in association with the disabled system information, such as the MIB and SIB1 of the power-saving cell. In addition to the MIB and SIB1, the anchor cell may also transmit some or all of the SIBx (x≧2) other than SIB1. Furthermore, the anchor cell may also transmit the scheduling information (SI-SchedulingInfo) of the power-saving cell's SIB. The terminal device can use the schedulingInfoList included in the SI-SchedulingInfo provided along with the power-saving cell's identification information to recognize whether the MIB, SIB1, or SIBx (x≧2) of the power-saving cell is being broadcast. The terminal device then receives the transport block on which the respective information is transmitted and can receive the MIB or SIB as needed. The base station device of the anchor cell broadcasts the MIB and SIB of low-power cells set to "Broadcasting" in schedulingInfoList. On the other hand, the base station device of the anchor cell does not broadcast the MIB and SIB of low-power cells set to "notBroadcasting" in schedulingInfoList.

[0021] Furthermore, the anchor cell base station equipment may provide MIBs and SIBs of low-power cells set to "notBroadcasting" in schedulingInfoList to terminal devices when it receives a request signal from those terminal devices. The request signal may be, for example, an RRCSystemInfoRequest message, which is a message at the Radio Resource Control (RRC) layer. Terminal devices may request the base station equipment to obtain system information set to "notBroadcasting" in schedulingInfoList using the RRCSystemInfoRequest message. Note that the anchor cell base station equipment does not have to broadcast all of the low-power cells' MIBs and SIBs. In this case, when a terminal device obtains the identification information of the low-power cell and a schedulingInfoList in which all MIBs and SIBs are set to "notBroadcasting", it can receive the MIBs and SIBs by sending a request signal specifying the system information to be requested.

[0022] Furthermore, when the anchor cell's base station equipment establishes a connection with a terminal device, it may provide the terminal device with system information about power-saving cells that have not been transmitted. For example, when a terminal device transitions from the RRC_Idle state to the RRC_Connected state in the anchor cell, the anchor cell's base station equipment may provide the terminal device with untransmitted system information about power-saving cells, for example, through a separate RRC message. The terminal device may request the anchor cell to provide system information that is indicated in SI-SchedulingInfo as not being broadcast (set to "notBroadcasting") by sending a UEInformationRequest. The anchor cell's base station equipment may provide system information about power-saving cells that are not broadcast using dedicatedSIB1-Delivery and dedicatedSystemInformationDelivery included in UEInformationResponse. Note that an anchor cell may function as an anchor cell for multiple power-saving cells, in which case the terminal device may obtain untransmitted system information from the anchor cell's base station equipment for multiple power-saving cells. For example, a terminal device may request information from an anchor cell for each of several low-power cells using individual RRC messages such as UEInformationRequest. The terminal device may, for example, send a request signal to the base station device of the anchor cell, associating the identification information of the low-power cell with the type of system information being requested, and obtain the necessary information.

[0023] As described above, if a cell in which the terminal device is not located is an anchor cell, the terminal device may move to the anchor cell and receive information there. Here, for example, the terminal device may move to the anchor cell and acquire information before deciding to reselect a cell to a power-saving cell, or it may move to the anchor cell and acquire information after deciding to reselect a cell to a power-saving cell.

[0024] For example, suppose the terminal device 121 recognizes, based on a signal received in the first cell 111 where it is located, that the second cell 112 has a power-saving function and has enabled that function, and that the anchor cell of the second cell 112 is the third cell 113. In this case, even if the measurement result of the radio signal of the second cell 112, which is a power-saving cell, does not satisfy predetermined conditions such as the conditions for cell selection or cell re-selection, the terminal device can measure the radio quality of the SSB and SIB of the third cell 113, which is the anchor cell. Then, if the measurement result of the SSB and SIB of the third cell 113 satisfies predetermined conditions (for example, if the radio quality is sufficiently good), the terminal device can decode the SSB and SIB of the third cell 113 and obtain the system information of the second cell 112. Furthermore, if multiple anchor cells are specified, the terminal device may identify one of those anchor cells that satisfies certain conditions and decode the SSB and SIB transmitted from that cell. Here, the first cell 111 may notify the terminal device of the timing for receiving information transmitted by the third cell 113, which is the anchor cell. The terminal device will remain in the area of ​​the first cell 111 and receive the signal transmitted by the third cell 113. At the reception timing notified by the first cell 111, the terminal device will stop receiving signals in the first cell 111 and execute the process of receiving information transmitted by the third cell 113. For this reason, the first cell 111 may instruct the reception timing to receive information from the anchor cell at a time other than when it transmits a paging signal. Also, if the terminal device is instructed to receive information from the anchor cell at the time it transmits a paging signal, it may decide whether to perform paging signal reception or information reception from the anchor cell.

[0025] The terminal device 121 is configured to receive a value indicating the priority of cell selection from the first cell 111 that is currently in the area, as in the conventional configuration. When the wireless quality of the first cell 111 that is currently in the area deteriorates below a predetermined reference level, the terminal device 121 measures the wireless quality of an adjacent cell with a lower priority than the first cell 111 that is currently in the area. Here, for example, depending on the relationship between the priority of the second cell 112, which is in a power-saving state, and the priority of the third cell 113, which is the anchor cell, a situation may arise where only the wireless signal of the second cell 112, which is in a power-saving state, is measured, and the wireless signal of the third cell 113, which is the anchor cell, is not measured. For example, if the priority of the second cell 112 is greater than or equal to the priority of the first cell 111, and the priority of the third cell 113 is lower than the priority of the first cell 111, and the wireless quality of the first cell 111 is not below a predetermined value, then the second cell 112 is measured, but the third cell 113 is not measured. In this case, the terminal device 121 can measure some of the signals transmitted from the second cell 112, but it does not measure the third cell 113, and therefore it may not be able to obtain system information that transmission has been stopped in the second cell 112. For this reason, in this embodiment, for example, the terminal device may be configured to measure the anchor cell when it starts measuring the power-saving cell, regardless of the priority of the anchor cell. Alternatively, the terminal device may change the priority of the anchor cell instructed by the base station device to the priority of the power-saving cell. This ensures that the terminal device can reliably obtain system information about the power-saving cell when it is measured. The priority information is notified to the terminal device by cellReselectionPriority specified in SIB2, SIB3, SIB4, or the RRC Release message.

[0026] Furthermore, the terminal device may decode the anchor cell's SSB and SIB regardless of the anchor cell's synchronization signal or SSB radio quality. For example, the terminal device may start the SSB and SIB decoding process of the anchor cell when the radio quality of the power-saving cell meets the criteria for cell re-selection. If the terminal device fails to decode the SSB and SIB after attempting to decode them regardless of the anchor cell's radio quality, it may re-execute the acquisition and decoding of the information after a certain period of time has elapsed. In addition, if the terminal device fails to complete the reception process of the power-saving cell's system information in the anchor cell for a predetermined number of consecutive times or over a predetermined period of time, it may exclude the power-saving cell associated with that anchor cell from the target of cell selection and cell re-selection. The predetermined number of times or predetermined period may be notified to the terminal device from the first cell 111 in which the terminal device is located. If there are multiple anchor cells, the terminal device may use a different anchor cell from the one that failed to decode the information as the anchor cell for the power-saving cell.

[0027] Furthermore, the terminal device may attempt to decode the SSB and SIB of the third cell 113, which is an anchor cell, if the measurement result of the radio signal of the second cell 112, which is a low-power cell, satisfies predetermined conditions such as the conditions for targeting cell selection or cell re-selection. In other words, the terminal device may attempt to decode the SSB and SIB of the third cell 113 when it has determined that the second cell 112 is the destination cell through cell selection or cell re-selection. The terminal device may also attempt to decode the SSB and SIB of the third cell 113 even if the measurement result of the radio signal of the second cell 112 satisfies predetermined conditions, but before it has been determined that it is the destination cell through cell selection or cell re-selection. In addition, the terminal device may attempt to decode the SSB and SIB of the third cell 113 if both the measurement result of the radio signal of the second cell 112, which is a low-power cell, and the measurement result of the radio signal of the third cell 113, which is an anchor cell, satisfy predetermined conditions. For example, the terminal device may decode the SSB and SIB of the third cell 113 when the second cell 112 satisfies the conditions for cell selection and cell re-selection, and the wireless quality is sufficiently good to enable decoding of the SSB and SIB of the third cell.

[0028] In one example, the terminal device measures the wireless quality of the second cell 112 in a power-saving state, and can also measure the wireless quality of the third cell 113, which is the anchor cell of the second cell 112, regardless of the wireless quality of the second cell 112. When the second cell 112 satisfies the cell movement conditions, the terminal device performs SSB or SIB decoding of the third cell 113 if the wireless quality of the third cell 113 is above a predetermined threshold. On the other hand, if the wireless quality of the wireless signal of the third cell 113 is below a predetermined threshold, the terminal device does not decode the SSB or SIB of the third cell 113. Subsequently, if the second cell 112 still satisfies the cell movement conditions and the wireless quality of the wireless signal of the third cell 113 becomes above a predetermined threshold, the terminal device may perform SSB or SIB decoding of the third cell 113. The predetermined threshold here may be notified to the terminal device from the first cell 111 where the terminal device is located. This prevents wasting power in the terminal device by performing unnecessary decoding processing in situations where the wireless quality of the third cell 113 is poor and there is a high probability of failure in decoding the SSB or SIB of the third cell 113.

[0029] Furthermore, the terminal device may prevent decoding of the SSB and SIB of the third cell 113, which is an anchor cell, before the second cell 112, which is a low-power cell, meets the criteria for cell selection or cell re-selection. That is, the terminal device may start receiving the SSB of the third cell 113 and decode the SIB depending on whether the radio quality of the second cell 112 meets the criteria for cell selection or cell re-selection. The terminal device attempts to decode the SSB and SIB of the third cell 113, provided that the second cell 112 meets the conditions for moving to a cell in the area. Furthermore, if a predetermined period of time has elapsed without successful decoding of the SSB and SIB of the third cell 113, the terminal device may decide not to make the second cell 112 a destination cell for cell selection or cell re-selection. Furthermore, even before the predetermined period has elapsed, if the second cell 112 does not meet the conditions for moving to a cell in the area (for example, if the wireless quality does not meet the standard) before the decoding of the SSB and SIB of the third cell 113 is successful, the terminal device may decide not to make the second cell 112 a destination cell for cell selection or cell re-selection. In this case, after the terminal device has started the system information reception process for the second cell 112, it stops the system information reception process for the second cell 112 in accordance with the change in the state of the second cell 112. In addition, the terminal device may decide not to make the second cell 112 a destination cell for cell selection or cell re-selection if the number of attempts to decode the SSB of the third cell 113 reaches a predetermined number without successful decoding, or if the second cell 112 changes to a state that does not meet the conditions for moving to a cell in the area before the number of decoding attempts reaches a predetermined number. The predetermined period or number of times mentioned here may be notified, for example, from the base station equipment of the first cell 111 to the terminal equipment.

[0030] The condition for a cell to move due to cell selection or cell re-selection is that there is an adjacent cell whose wireless quality is above a certain value within a certain period of time. The terminal device recognizes cells that satisfy this condition as candidate cells for cell re-selection. The terminal device ranks cells that satisfy the cell movement condition based on cell selection priority and wireless quality such as reference signal received power (RSRP), triggered by measurements of adjacent cells and serving cells. The rank is set higher for higher priority and higher for higher wireless quality. The terminal device then starts cell re-selection to the cell with the highest rank. The terminal device obtains the aforementioned certain period as Treselection and the aforementioned certain value as Thresh from the cells currently in the area.

[0031] Furthermore, if the terminal device does not have information on power-saving cells that have stopped transmitting, such as when the cell it is currently in is not an anchor cell, it may request the network to disable the power-saving function in the power-saving cell in order to obtain the necessary information directly from the power-saving cell instead of the anchor cell. For example, if the radio quality of the signal transmitted by the power-saving cell satisfies the movement conditions of the cell in which it is located, the terminal device sends a message to the base station device of the cell in which it is located to request that the power-saving function in the power-saving cell be disabled. Upon receiving this message, the base station device of the cell in which it is located sends a message to the base station device providing the power-saving cell to request that the power-saving function be disabled. Here, generally, when a certain quality degradation is confirmed in the cell in which it is located, the terminal device starts measuring the radio quality of cells with a lower cell selection priority than the cell in which it is located. At this time, if the cell selection priority of the power-saving cell is set lower than that of the cell in which it is located, the terminal device may request that the power-saving function of that power-saving cell be disabled when it is confirmed that the radio quality of the cell in which it is located has deteriorated and it starts measuring the radio quality of the power-saving cell. Furthermore, if the terminal device already holds information for transmitting an uplink signal to a power-saving cell, it may send the request message to the power-saving cell rather than to the cell in the area. Also, the terminal device may request the deactivation of the power-saving function of multiple power-saving cells collectively with a single uplink signal (for example, a single RRC message such as RRCSystemInfoRequest).

[0032] When a base station device in a power-saving cell receives a request to stop the power-saving function, it determines whether to resume transmitting system information such as MIB and SIB1, which had been stopped. If the base station device determines to resume transmitting system information, it notifies the base station device of the adjacent cell that the power-saving function has been stopped. The adjacent cell here may be the cell where the terminal device that sent the request to stop the power-saving function is located. The adjacent cell here may also include, for example, an anchor cell. However, it is not limited to these, and all base station devices that have notified terminal devices that the power-saving function has been stopped for a power-saving cell, including information indicating that the power-saving function is enabled or that it is an anchor cell (information as shown in Figure 2), may be notified that the power-saving function has been stopped. When the base station device of the cell in the area receives the notification of the power-saving function being stopped from the power-saving cell, it changes the information indicating the power-saving function's enabled status in the information as shown in Figure 2 and begins transmitting the updated information. By receiving this information, the terminal device can determine that the power-saving cell has stopped its power-saving function and started operating as a normal cell. Furthermore, a separate notification may be sent to the terminal device indicating that the power-saving cell has stopped its power-saving function. The terminal device can receive system information for the cell from the cell that has stopped its power-saving function. On the other hand, the base station device of the anchor cell may stop distributing system information for the power-saving cell. However, it is not limited to this, and the base station device of the anchor cell may continue distributing system information for the power-saving cell.

[0033] Furthermore, if the base station equipment of a power-saving cell determines that it will not resume transmitting system information, it may transmit information that can identify, for example, that the request is being rejected or that the power-saving function is being maintained, to the base station equipment or terminal equipment of the cell where the terminal equipment that sent the request signal is located. In this case, the terminal equipment may obtain the system information of the power-saving cell from the anchor cell as described above. The terminal equipment may also decide not to include the power-saving cell in the selection or re-selection process. In this case, the terminal equipment may exclude the power-saving cell from the selection or re-selection process for a predetermined period. In addition, if the terminal equipment does not receive notification that it will resume transmitting system information after sending the request signal described above for a predetermined period, it may determine that the power-saving cell has maintained its power-saving function and obtain the system information of that power-saving cell from the anchor cell. That is, if the terminal equipment does not receive notification that it will resume transmitting system information after sending the request signal described above for a predetermined period, it may perform the same processing as when it receives information that can identify that the request is being rejected or that the power-saving function is being maintained.

[0034] Furthermore, the base station equipment for a power-saving cell may be configured to determine whether to disable the power-saving function and resume transmitting system information if it receives a predetermined number of requests to disable the power-saving function from multiple terminal devices within a predetermined period. However, this is just one example, and the decision of whether or not to disable the power-saving function may be made based on other criteria. For example, the base station equipment for a power-saving cell may determine not to disable the power-saving function if the percentage of time during which the power-saving function was enabled within a predetermined period is less than or equal to a predetermined value.

[0035] Furthermore, if a terminal device moves to a cell that has transitioned from a power-saving cell to a normal cell (by performing cell reselection) and has completed receiving the necessary broadcast information in that cell, it may request the base station device of that cell to enable the power-saving function. In this case, when the base station device of that cell receives the request to enable the power-saving function, it will determine whether or not to enable the power-saving function. If the base station device of that cell determines to enable the power-saving function, it will enable the power-saving function and stop transmitting at least a portion of the system information that was being transmitted. The base station device of that cell will also notify the base station devices of adjacent cells, such as the cell in which the terminal device was located before cell reselection, that the power-saving function has been enabled. Based on the information received, the base station device of the adjacent cell will update the information shown in Figure 2, which is notified to the terminal device, to indicate that the power-saving function has been enabled in the cell from which the information was transmitted, and will send out the updated signal. In this way, the terminal device can efficiently acquire system information from each cell while saving power throughout the entire system.

[0036] The information shown in Figure 2 can be transmitted, for example, in each cell that is not currently running a power-saving function, using either System Information Block Type 2 (SIB2), System Information Block Type 3 (SIB3), or System Information Block Type 4 (SIB4). Conventionally, a terminal device receives SIB2 to SIB4 transmitted from the base station device in the cell it is currently in service with and obtains information about adjacent cells. This information about adjacent cells can be reused to notify the presence or absence of the power-saving function, its activation status, and anchor cell information. When the terminal device obtains this information about adjacent cells, it measures the wireless quality of the adjacent cell based on that information. For example, the information about adjacent cells may include cell selection priority information, and the terminal device may periodically measure the wireless quality of adjacent cells with a higher cell selection priority than the cell it is currently in service with, and measure the wireless quality of adjacent cells with a lower cell selection priority than the cell it is currently in service with only when the wireless quality of the cell it is currently in service has deteriorated below a threshold.

[0037] (Device configuration) Figure 3 illustrates an example of the hardware configuration of a base station device and a terminal device. In one example, the base station device and terminal device consist of a processor 301, ROM 302, RAM 303, storage device 304, and communication circuit 305. The processor 301 is a computer consisting of one or more processing circuits, such as a general-purpose CPU (Central Processing Unit) or ASIC (Application-Specific Integrated Circuit), and executes the overall processing of the device and the aforementioned processing by reading and executing programs stored in the ROM 302 and storage device 304. The ROM 302 is a read-only memory that stores information such as programs and various parameters related to the processing performed by the base station device and terminal device. The RAM 303 functions as a workspace when the processor 301 executes programs and is a random-access memory that stores temporary information. The storage device 304 consists of, for example, a removable external storage device. The communication circuit 305 consists of, for example, a circuit for LTE or 5G wireless communication. Although Figure 3 shows one communication circuit 305, the base station device and terminal device may have multiple communication circuits. For example, base station equipment and terminal equipment may have a common antenna for both LTE and 5G wireless communication circuits. Alternatively, base station equipment and terminal equipment may have separate antennas for LTE and 5G. Furthermore, base station equipment may also have a wired communication circuit used for communication with other base station equipment or core network nodes. Terminal equipment may also have a communication circuit for other wireless communication networks such as Wi-Fi. Additionally, base station equipment and terminal equipment may have separate communication circuits 305 for each of the multiple usable frequency bands, or they may have a common communication circuit 305 for at least a portion of those frequency bands.

[0038] Figure 4 shows an example of the functional configuration of a base station device. The base station device is composed of, for example, a cell information acquisition unit 401, a cell information notification unit 402, and a system information provision unit 403. Note that Figure 4 shows only the functions particularly relevant to this embodiment, and various other functions that the base station device may have are omitted from the illustration. For example, the base station device naturally has other functions that LTE and 5G base station devices generally have. Also, the functional blocks in Figure 4 are shown schematically, and each functional block may be implemented as an integrated unit or further subdivided. Furthermore, each function in Figure 4 may be implemented, for example, by the processor 301 executing a program stored in the ROM 302 or storage device 304, or by a processor located inside the communication circuit 305 executing predetermined software. Note that the details of the processing performed by each functional unit will not be explained in detail here, and only the general functions will be outlined.

[0039] The cell information acquisition unit 401 exchanges information with adjacent cells regarding whether its own device supports the power saving function, whether the power saving function is enabled if it is supported, and information about the anchor cell if the power saving function is enabled. For example, the base station device of the first cell 111 acquires information from the base station device of the second cell 112 that the power saving function is supported and enabled in the second cell 112, and that the anchor cell is the third cell 113. The base station device of the first cell 111 may also receive notification from the base station device of the third cell 113 that the third cell 113 does not support the power saving function. Furthermore, the base station device of the first cell 111 may notify the base station devices of the second cell 112 and the base station devices of the third cell 113 that the first cell 111 supports the power saving function but has not enabled it, and that the anchor cell if enabled is the third cell 113. Furthermore, at least some of this information may be obtained at each base station device not through information exchange between base station devices, but for example, by pre-configuration by the telecommunications carrier. For example, information indicating whether or not a power saving function is supported and anchor cell information may be pre-configured, and only the information indicating whether or not the power saving function is enabled may be exchanged between base station devices. Pre-configuration by the telecommunications carrier may be notified to each base station device via the network from a predetermined control device (not shown), for example.

[0040] The cell information notification unit 402 aggregates the information acquired by the cell information acquisition unit 401 and notifies the terminal device. The information notified here is, for example, the information shown in Figure 2. In addition, the cell information notification unit 402 may further notify information indicating the priority for each adjacent cell for the terminal device to perform cell selection / cell re-selection, as in the conventional method.

[0041] The system information provision unit 403 provides information such as MIBs and SIBs of the cells it provides, and also provides system information such as MIBs and SIBs that are not transmitted in the power-saving cell when the cell it provides becomes an anchor cell for other cells. If the system information provision unit 403 is not functioning as an anchor cell for the power-saving cell, it may only send the system information of the cell it provides. Furthermore, when the power-saving function is used in the device, the system information provision unit 403 may stop the transmission of some system information and transmit only some signals, such as synchronization signals.

[0042] Figure 5 shows an example of the functional configuration of a terminal device. The terminal device is composed of, for example, an information acquisition unit 501 and a cell selection processing unit 502. Note that Figure 5 shows only the functions particularly relevant to this embodiment, and various other functions that the terminal device may have are omitted from the illustration. For example, the terminal device naturally has other functions that LTE and 5G terminal devices generally have. Also, the functional blocks in Figure 5 are shown schematically, and each functional block may be implemented as an integrated unit or further subdivided. Furthermore, each function in Figure 5 may be implemented, for example, by the processor 301 executing a program stored in the ROM 302 or storage device 304, or by a processor located inside the communication circuit 305 executing predetermined software. Note that the details of the processing performed by each functional unit will not be explained in detail here, and only the general functions will be outlined.

[0043] The information acquisition unit 501 acquires various information, such as system information, from surrounding base station equipment. For example, the information acquisition unit 501 acquires system information transmitted from the base station equipment of the cell in which it is located. The information acquisition unit 501 also acquires system information of cells adjacent to the cell in which it is located. Here, for example, the information acquisition unit 501 acquires from the base station equipment of the cell in which it is located whether one or more adjacent cells have a power saving function, whether that function is enabled if they have a power saving function, and information that can identify the anchor cell to which system information is transmitted if the power saving function is enabled. When the information acquisition unit 501 acquires system information that has been stopped from being transmitted in a power saving cell that has a power saving function and has that power saving function enabled, it acquires that system information from the anchor cell. The cell selection processing unit 502 performs cell selection or cell re-selection based on the measurement results of radio signals from surrounding base station equipment. Furthermore, the cell selection processing unit 502 may decide whether or not to include a power-saving cell in the selection / re-selection process based on whether or not it was possible to obtain system information from the anchor cell indicating that transmission has been stopped. The cell selection processing unit 502 may also perform a process to obtain system information from a power-saving cell, regardless of the priority of the anchor cell's selection. In addition, if the first priority of the anchor cell's selection is lower than the second priority of the power-saving cell's selection, the cell selection processing unit 502 may treat the first priority as the same as the second priority and include it in the measurement. Furthermore, the cell selection processing unit 502 may decide whether or not to include a power-saving cell in the selection / re-selection process based on whether or not the power-saving function has been stopped in response to a request to stop the power-saving function.

[0044] (Process flow) Next, an example of the processing flow executed in the wireless communication system of this embodiment will be explained using Figure 6. Here, we will describe an example where the cell in which the terminal device is located and the anchor cell of the power-saving cell are different, and the terminal device receives system information from the anchor cell whose transmission has been stopped in the power-saving cell. First, the terminal device obtains information about adjacent cells from the base station device of the cell in which it is located (S601). As described above, the information here includes, for each adjacent cell, the cell identifier, whether or not the cell supports the power-saving function, whether or not the power-saving function is enabled if it is supported, and information about the anchor cell from which the transmission of system information whose transmission has been stopped if the power-saving function is enabled is transmitted. The terminal device measures the radio signal transmitted from the base station device of the power-saving cell and may, for example, obtain only some of the system information whose transmission has not been stopped (S602). Note that the base station device of the power-saving cell does not have to transmit all of the system information, and the terminal device may only measure the radio quality for the power-saving cell. Subsequently, the terminal device obtains system information from the base station device of the anchor cell, based on the information acquired in S601, regarding the system that has stopped transmitting in the power-saving cell (S603).

[0045] Figure 7 shows an example of the processing flow when a terminal device sends a message to the base station device of a power-saving cell requesting the deactivation of its power-saving function. Similar to S601, the terminal device obtains information about adjacent cells from the cell it is currently in service with (S701). Then, if the terminal device needs to obtain system information for the power-saving cell, it sends a message to the power-saving cell requesting the deactivation of its power-saving function (S702). Although Figure 7 shows an example of processing when the message is sent directly to the power-saving cell, the message may also be sent from the terminal device to the base station device of the cell it is currently in service with, and then forwarded from the base station device of the cell it is currently in service with to the base station device of the power-saving cell. When the base station device of the power-saving cell receives the message, it determines whether or not to deactivate its power-saving function. If the base station device of the power-saving cell does not deactivate its power-saving function, the terminal device can obtain information about the power-saving cell from the anchor cell using the processing shown in Figure 6. On the other hand, if the base station device of the power-saving cell deactivates its power-saving function (S703), the terminal device can obtain system information for that cell from that base station device (S704).

[0046] By acquiring this system information, the terminal device can perform cell reselection and reside in a low-power cell.

[0047] As described above, by stopping the transmission of system information from some cells, power consumption can be reduced while still allowing terminal devices to be located in those cells, enabling efficient system operation. Therefore, it becomes possible to contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote sustainable industrialization and foster innovation."

[0048] The invention is not limited to the embodiments described above, and various modifications and changes are possible within the scope of the gist of the invention.

Claims

1. In a wireless communication network in which communication services are provided to a terminal device using at least one of a plurality of cells, the terminal device is: For each adjacent cell adjacent to the cell in which the terminal device is located, an acquisition means for acquiring setting information for the terminal device to receive system information transmitted upon request for power saving purposes, In a base station device that provides a power-saving cell, when the power-saving function stops, a receiving means receives updated configuration information corresponding to the cessation of the power-saving function, A terminal device characterized by having the following features.

2. The terminal device according to Claim 1, further comprising a transmission means for transmitting a request message to the base station device providing the power-saving cell, requesting the cessation of the power-saving function when the radio quality of the signal transmitted in the power-saving cell satisfies the movement conditions of the cell in service.

3. The terminal device according to claim 2, wherein the transmitting means transmits the request message when the radio quality of the signal transmitted in the low-power cell satisfies the movement conditions of the cell in service and has prior information for transmitting an uplink signal to the low-power cell.

4. The terminal device according to claim 2, further comprising means for excluding the power-saving cell from the target and performing cell selection or cell reselection if no notification of resuming transmission of system information is received for a predetermined period after the request message has been sent.

5. The terminal device according to claim 1, further comprising means for excluding the power-saving cell from the target and performing cell selection or cell reselection if the system information reception process for the power-saving cell is not completed within a predetermined period.

6. The terminal device according to claim 5, characterized in that it has means for obtaining information indicating the predetermined period from a base station device that provides the cell in service area.

7. The terminal device according to claim 1, characterized in that the acquisition means acquires the setting information from a base station device that provides the cell in the area.

8. The terminal device according to claim 1, wherein the setting information includes information on whether or not a power saving function that stops the periodic transmission of system information is enabled.

9. A control method performed by a terminal device in a wireless communication network in which communication services are provided to a terminal device using at least one of a plurality of cells, For each adjacent cell adjacent to the cell in which the terminal device is located, an acquisition step is made to acquire setting information for the terminal device to receive system information that is transmitted upon request for power saving purposes. In a base station device that provides a power-saving cell, when the power-saving function stops, a receiving step is performed to receive updated configuration information corresponding to the cessation of the power-saving function. A control method characterized by including

10. A program for causing a computer provided in a terminal device to execute the control method described in claim 9, in a wireless communication network where communication services are provided to the terminal device using at least one of a plurality of cells.

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