Base station, network device, communication method, and program for efficiently performing paging

Abstract

To provide a base station, a network device, a communication method, and a program for efficiently performing paging in a mobile communication system.SOLUTION: In a mobile communication system, a base station 112 capable of forming multiple beams having a common tracking area code defined in the cellular communication standard of the Third Generation Partnership Project, includes control means for identifying one or more first beams 144 included in the multiple beams and identified corresponding to the location of a terminal 101 at the time of location registration, and for controlling the distribution of a paging signal, and when a predetermined condition is satisfied, the paging signal is distributed using the first beam 144, and the paging signal is not distributed using second beams 145, 146 different from the first beam 144.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a technique for efficiently performing paging.

Background Art

[0002] In the 5th generation mobile communication system (5G) of the 3rd Generation Partnership Project (3GPP), by applying transmission beamforming at a base station, it is possible to concentrate the reception intensity of a signal in a specific direction and extend the communication distance. On the other hand, since the reception intensity decreases in other directions and the range where the signal reaches becomes narrow, multi-beam operation is performed to form coverage using a plurality of beams. For example, Non-Patent Document 1 defines a paging distribution method in a multi-beam base station capable of forming a plurality of beams.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Non-Patent Document 1, it is stipulated that a base station transmits the same paging signal for all beams. According to this regulation, when a base station distributes a paging signal in all beams, the overhead increases. As a result, the resources available for data transmission decrease, and the actual throughput decreases. The present invention provides a technique for efficiently performing paging in a mobile communication system and enabling effective utilization of resources.

Means for Solving the Problems

[0005] A base station according to an aspect of the present invention is a base station capable of forming a plurality of beams having a common tracking area code defined in a cellular communication standard of the Third Generation Partnership Project (3GPP), the base station comprising: specifying means for specifying one or more of the first beams corresponding to the position at the time of location registration of a terminal; and control means for controlling the distribution of paging signals, the control means performing the distribution of the paging signals using the first beam and not performing the distribution of the paging signals using a second beam different from the first beam when a predetermined condition is satisfied.

[0006] A network device according to an aspect of the present invention communicates with a base station capable of forming a plurality of beams having a common tracking area code defined in a cellular communication standard of the Third Generation Partnership Project (3GPP), and operates as an Access and Mobility Function, the network device including notification means for giving a notification for causing the base station to execute predetermined control of the distribution of paging signals when a predetermined condition is satisfied, the predetermined control being to perform the distribution of the paging signals using one or more first beams determined from among the plurality of beams based on position information at the time of location registration of a terminal and not to perform the distribution of the paging signals using a second beam different from the first beam among the plurality of beams.

Advantages of the Invention

[0007] According to the present invention, in a mobile communication system, by performing paging efficiently, effective use of resources becomes possible.

Brief Description of the Drawings

[0008]

Figure 1

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Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of the features described in the embodiments are essential to the invention. Two or more of the plurality of features described in the embodiments may be arbitrarily combined. Also, the same or similar configurations are given the same reference numerals, and duplicate explanations are omitted.

[0010] (System Configuration) Fig. 1 shows a configuration example of a mobile communication system according to this embodiment. The mobile communication system is, for example, a cellular communication system compliant with the cellular communication standard of the 3rd Generation Partnership Project (3GPP (registered trademark)). However, it is not limited to this, and the following discussion can be applied to a mobile communication system compliant with any wireless communication standard. The mobile communication system includes, for example, terminal 101, base stations 111, 112, 113, 114, and 115, and AMF 121. AMF is an abbreviation for Access and Mobility Management Function. Note that base stations 111 to 115 may be collectively referred to as base station 110. TAa 131 and TAb 132 are units of areas used to manage the location information of terminal 101. TA is an abbreviation for Tracking Area. Each TA may include a plurality of base stations 110. For example, TAa 131 includes base stations 111, 112, and 113. Also, TAb 132 includes base stations 114 and 115. Note that each TA may include four or more base stations 110. Beams 141 to 143 are beams formed by base station 111. Also, beams 144 to 146 are beams formed by base station 112. Each of beams 141 to 146 is formed to cover different areas. Also, the areas covered by each beam may partially overlap, for example, like beam 141 and beam 144. Note that beams 141 to 143 and beams 144 to 146 each show a part of a plurality of beams formed by base station 111 and base station 112, respectively, and each base station may form four or more beams.

[0011] Terminal 101 is a terminal used by a user and exchanges radio signals with base station 110 via a wireless medium. Terminal 101 can be called User Equipment (UE). Terminal 101 includes, for example, smartphones, mobile phones, personal computers, tablet terminals, wearable terminals, IoT (Internet of Things) terminals, etc. In FIG. 1, an example is shown where terminal 101 and base station 111 are communicating via a wireless medium. However, two or more terminals 101 may be connected to one base station 110, and one terminal may be connected to two or more base stations 110. Base station 110 exchanges radio signals with terminal 101 via a wireless medium. Base station 110 includes, for example, gNB (next Generation Node B), eNB (evolved Node B), etc. The range within which communication with base station 110 is possible, provided by base station 110, is called a cell. Also, base station 110 can communicate with terminal 101 using beams formed by a plurality of antennas. Forming a beam can be called beamforming. Base station 110 can simultaneously form a plurality of beams using beamforming. In this case, a plurality of cells with different covered areas can be simultaneously provided by one base station 110. That is, a plurality of cells may be formed by each beam, or one cell using a plurality of beams may be formed by one base station 110. In FIG. 1, base station 111 forms a plurality of beams including beam 141 to beam 143, and terminal 101 communicates with base station 111 using beam 141 among them. On the other hand, terminal 101 can also receive signals transmitted using beam 144 formed by base station 112. Also, as terminal 101 moves, terminal 101 can receive signals transmitted by each of beam 141 to beam 146, and can also receive signals transmitted by each of base stations 113 to 115. Each of base stations 110 is connected to AMF 121 via a wired network or a wireless network (not shown).

[0012] The AMF 121 performs procedures and management such as the registration, connection, and movement of the terminal 101 to / from the network. For example, when the terminal 101 is registered to the network, the AMF 121 assigns a registration area to the terminal 101. The registration area can be composed of a plurality of tracking areas (TAs). Each tracking area can be composed of cells provided by a plurality of base stations 110. In FIG. 1, a plurality of base stations 110 including base stations 111, 112, and 113 constitute a tracking area (TA) a131, and a plurality of base stations 110 including base stations 113 and 114 constitute a TA b132. The TA a131 and the TA b132 can be collectively referred to as TA 130. A common tracking area code (TAC) is assigned to each of the base stations 110 that constitute the same tracking area. Note that a tracking area identifier (TAI) composed of adding an MCC (Mobility Country Code) and an MNC (Mobile Network Code) to the TAC may be used to identify the tracking area. When the base station 110 uses a plurality of beams simultaneously, each of the cells provided by each beam may belong to the same TA 130, or each may belong to a different TA 130. When the terminal 101 is present within any TA 130, the position of the terminal 101 can be associated with the TA 130 and managed by the AMF 121. The fact that the terminal 101 is present within the TA 130 is also expressed as the terminal 101 being in the TA 130. As an example, when communication traffic destined for the terminal 101 in the idle state occurs, all the base stations 110 that constitute the TA 130 associated with and registered to this terminal 101 perform a call (paging) to this terminal 101. Also, when the terminal 101 detects that it has gone outside the registration area assigned to its own device, it starts a registration update procedure. In this case, the AMF 121 can assign a new registration area to the terminal 101.

[0013] Figure 2 shows an example of a sequence when the terminal 101 registers with the network. For example, the information of the terminal 101 including location information can be registered and managed in the AMF 121 through a sequence like this example. First, the terminal 101 detects a synchronization signal periodically transmitted by the base station 110 and obtains notification information (S201). The synchronization signal can be composed of two signals, a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS). Also, the notification information can include regulation information for the terminal 101 to connect to the base station 110, common channel information, random access channel information, etc. Note that the base station 110 can transmit an SS / PBCH block composed of the synchronization signal and the notification information. Subsequently, the terminal 101 can receive System Information Block (SIB) 1 to obtain system parameters necessary for a random access procedure to connect to the base station 110. SIB1 can include uplink carrier information, random access signal configuration information, etc. Based on the information obtained by SIB1, the terminal 101 executes a random access procedure and connects to the base station 110 (S202). Subsequently, the terminal 101 transmits an RRC (Radio Resource Control) connection request (RRC SetupReq) to exchange RRC messages with the base station 110 (S203). When the terminal 101 receives an RRC connection setup (RRC Setup) from the base station 110 (S204), it transmits an RRC connection setup complete (RRC SetupComplete) to the base station 110 (S205). Through the above procedures, the terminal 101 can exchange RRC messages with the base station 110. The terminal 101 can communicate with network functions such as the AMF 121 using RRC messages. For example, the terminal 101 can include a registration request in the signal of RRC connection setup complete and transmit it. The registration request can be transmitted as a NAS (Non-Access Stratum) signal message for communication between the terminal 101 and the AMF 121. The base station 110 forwards the registration request received from the terminal 101 to the AMF 121 (S206).The base station 110 can transfer an encapsulated registration request (NAS signal message) to the AMF 121 using the NG-AP (NG Application Protocol) for communication between the base station 110 and the AMF 121. In this case, the base station 110 can use the Initial UE Message as an NG-AP message. The registration request may include an NR CGI (New Radio Cell Global Identity) and a tracking area identifier (TAI) as information regarding the location of the terminal 101 (NR user Location Information). The NR CGI is composed of a PLMN (Public Land Mobile Network) Identity and an NR Cell Identity. Also, the TAI is composed of a PLMN Identity and a TAC. Further, in the case of the first registration procedure of the terminal 101, the registration type (5GS registration type) included in the registration request may be indicated as an initial registration. When the AMF 121 registers the information of the terminal 101 in its own device, it transmits a NAS signal message of Registration Accept to the base station 110 (S207). The Registration Accept may include a TAI list notifying all TAIs included in the registration area assigned to the terminal 101, and information (T3512 value) specifying the period for which the location registration procedure should be executed when the terminal 101 is in any TA130 included in the registration area. The AMF 121 can transmit the NAS signal message of Registration Accept using the Downlink NAS Transport of the NG-AP. The base station 110 transfers the NAS signal message of Registration Accept to the terminal 101 using the RRC DL Information Transfer message (S208). The terminal 101 transmits a NAS signal message of Registration Complete to the base station 101 using the RRC UL Information Transfer message (S209).The base station 110 transfers the NAS signal message indicating the completion of registration to the AMF 121 using the Uplink NAS Transport of the NG-AP (S210). When the NAS signal message indicating the completion of registration is received by the AMF 121, the registration of the terminal 101 to the network is completed.

[0014] Even after the registration of the terminal 101 to the network is completed, the terminal 101 performs periodic registration updates. For example, when the connection state with the base station 110 transitions to the Idle state (waiting state), the terminal 101 sets a timer based on the T3512 value indicated by the AMF 121 in the registration reception, and can notify the AMF 121 of the information on the TA in which it is located when the timer expires. The procedure for the terminal 101 to perform periodic registration updates is the same as the procedure shown in FIG. 2, and the difference may be that the registration type included in the registration request in S205 indicates periodic registration updating. Also, after the registration update is completed, the terminal 101 can release the context information used for the communication for the registration update. On the other hand, when the terminal 101 moves outside the registration area in the Idle state, it can update the registration (Mobility registration Update). In this case, after moving outside the registration area, the terminal 101 performs cell reselection. The cell reselection can be performed by detecting the synchronization signal and acquiring the notification information, similar to S201 in FIG. 2. The terminal 101 can connect to the reselected cell using the random access procedure and perform the registration update by executing the procedures after S202. Note that the difference from the procedure in the case of the initial registration may be that the registration type included in the registration request in S205 indicates Mobility registration updating.

[0015] When the base station 110 uses a plurality of beams, the base station 110 transmits an SS / PBCH block for each beam. For example, the base station 110 can transmit an SS / PBCH block for each beam at each of a plurality of candidate positions for transmitting an SS / PBCH block provided in one radio frame. The terminal 101 can perform symbol timing synchronization and Local ID detection using the PSS transmitted by each beam at each candidate position, and can execute radio frame synchronization and cell group ID detection using the SSS. The terminal 101 can obtain the physical ID (PCI) of the cell based on a combination of this information. Also, the terminal 101 can measure the received power of the cell (which may also be called Reference Signal Receive Power, RSRP) and the received quality (which may also be called Reference Signal Receive Quality, RSRQ), etc. based on the received SSS. The terminal 101 can select an optimal beam based on the measured received power and received quality. Also, the terminal 101 performs a random access procedure to the base station 110 and executes a registration update using a random access channel (RACH) associated with the selected beam (or the SS / PBCH block associated with the beam). That is, the base station 110 can recognize the beam selected by the terminal 101 based on the random access channel used by the terminal 101.

[0016] FIG. 3 shows an example of a sequence when paging an idle terminal 101. For the same processing as in FIG. 2, the same reference numerals are assigned and the description is omitted. First, the idle terminal 101 executes an intermittent reception operation in which it periodically performs a reception operation (S301 to S303). The intermittent reception operation may be called DRX (Discontinous Reception). Also, the period for executing the intermittent reception operation may be called a DRX cycle. Also, the period during which the terminal 101 periodically performs a reception operation in order to receive a paging signal may be called a paging occasion (PO). When communication traffic destined for the terminal 101 occurs, the AMF 121 transmits a paging request to the base station 110 using an NG-AP Paging request (S304). The paging request may be transmitted to all the base stations 110 constituting the registration area assigned to the terminal 101 that is the paging target. For example, in the configuration of FIG. 1, the paging request is distributed to the base stations 111, 112, and 113 constituting the TAa131 included in the registration area assigned to the terminal 101, and is not distributed to the base stations 114 and 115 not included in the registration area. The paging request may include an identifier (UE Paging Identity) for identifying the terminal 101 and information (such as TAI) for identifying the base station that is the paging destination. When the base station 110 that has received the paging request is the target of the paging request, it executes paging using an RRC Paging message (S305). The base station 110 may arrange a paging occasion in the DRX cycle and transmit a paging signal (RRC message) including a UE-list. The UE-list is a list of identifiers for identifying the terminal 101 that is the paging target, and the identifier for identifying the terminal 101 may be a 5G-S-TMSI (Temporary Mobile Subscription Identifier), an IMSI (International Mobile Subscription Identifier), or the like.Similar to FIG. 2, the terminal 101 executes a random access procedure (S202) and an RRC connection setup procedure (S203 to S205), and transmits a NAS signal message of a service request to the AMF 121 using the established RRC connection. The NAS signal message of the service request can be transmitted encapsulated in an RRC connection setup completion message. The base station 110 can transfer the NAS signal message of the service request to the AMF 121 using the Initial UE Message of the NG-AP. Through such a procedure, the AMF 121 identifies the base station 110 that can deliver communication traffic to the terminal 101.

[0017] When the base station 110 provides a cell using multiple beams by beamforming, the base station 110 transmits a paging signal using each beam. For example, if the base station 110 can form 64 mutually different beams, the base station 110 can transmit the same paging signal a total of 64 times (once for each beam). Also, since the terminal 101 cannot receive the paging signals transmitted by multiple beams simultaneously, it is necessary to adjust so that the periods of transmitting the paging signal in each beam do not overlap. As a result, the resources required to transmit the paging signal increase, and the frequency resources may not be used efficiently. FIG. 4 schematically shows an example of the relationship between the radio frame and the paging occasion in the base station 110 when beamforming is not performed. In one cycle of the DRX cycle (for example, 1280 ms (milliseconds)), a plurality of radio frames in which paging occasions are set can be transmitted. One radio frame can be, for example, 10 ms long. A radio frame in which a paging occasion is set can be called a paging frame (PF). The paging frame including the paging occasion assigned to the terminal 101 can be specified, for example, as follows. That is, the SFN (Sequence Frame Number) specifying each paging frame is specified by (SFN + PF_offset) mod T = (T div N) * (UE_ID mod N). Here, T is the DRX cycle of the terminal 101, N is the total number of paging frames in the DRX cycle, PF_offset is an offset for determining PF, and UE_ID is 5G - S - TMSI mod 1024. For example, when T = 1280 (ms) and N = 128, as shown in FIG. 4, each radio frame can include one paging occasion. Note that when T is indicated in units of radio frames, T = 128 (radio frames) can be obtained. When performing the discontinuous reception operation in one DRX cycle, the terminal 101 can monitor one paging occasion at the SFN specified as described above.On the other hand, a base station that uses a plurality of beams by beamforming can transmit the same message in each beam. FIG. 5 schematically shows an example of the relationship between a radio frame and a paging occasion in a base station 110 that uses 64 beams. Different from the example of FIG. 4, the base station 110 can set a paging occasion corresponding to each beam in each paging frame. For example, when the base station 110 uses 64 beams, 64 paging occasions can be set, and the terminal 101 can monitor one or more of the paging occasions corresponding to each beam in the SFN specified as described above. In this way, as the number of beams used by the base station 110 increases, the frequency resources consumed for transmitting the paging signal increase.

[0018] In view of such circumstances, in this embodiment, between the base station 110 capable of forming a plurality of beams and the terminal 101, one or more first beams specified corresponding to the position at the time of registration or registration update (hereinafter referred to as position registration) of the position information of the terminal 101 are specified. Then, when a predetermined condition is satisfied, the base station 110 transmits a paging signal using the first beam, and executes transmission control of the paging signal so as not to distribute the paging signal using a second beam different from the first beam. Note that the first beam and the second beam belong to the same TA and have a common tracking area code. The one or more first beams specified corresponding to the position at the time of position registration of the terminal 101 may be, for example, beams associated with the RACH used when the terminal 101 performs position registration. Also, the one or more first beams specified corresponding to the position at the time of position registration of the terminal 101 may be beams including the position of this terminal 101 in the coverage based on the position information of the terminal 101. Further, the one or more first beams specified corresponding to the position at the time of position registration of the terminal 101 may be one or more beams associated with these beams. The one or more first beams specified corresponding to the position at the time of position registration of the terminal 101 are not limited to the above, and may be various beams described in this specification. For example, the base station 110 may use, as the first beam, a beam associated with the random access channel used when the terminal 101 performs position registration. Note that when it is assumed that the terminal 101 moves, the base station 110 predicts the moving destination of the terminal based on the position of the terminal 101 when the terminal 102 performs position registration, and may use the moving destination as the position at the time of the above-described position registration of the terminal 101 for specifying the first beam. The first beam specified in this way may also be included in the one or more first beams specified corresponding to the position at the time of position registration of the terminal 101. In this way, the base station 110 may transmit a paging signal using only the beam selected by the terminal 101 as the optimal beam.Therefore, the number of slots in which a paging occasion is set to transmit a paging signal is significantly reduced, and since it can be used for other purposes such as transmitting data signals, it becomes possible to efficiently utilize frequency resources. In the case of this example, for instance, in FIG. 5, the number of slots in which a paging occasion is set is one. Hereinafter, when the base station 110 transmits a paging signal using a first beam and executes transmission control of the paging signal so as not to distribute the paging signal using a second beam different from the first beam, it may be referred to as distribution of the paging signal using only the first beam.

[0019] The base station 110 can determine the beam selected by the terminal 101 during location registration and one or more beams associated with this beam as the first beam, and can distribute paging signals using only the first beam. For example, when the number of beams formed by the base station 110 increases, the area covered by one beam becomes narrower. Therefore, if a paging signal is transmitted using only one beam, the possibility that the terminal 101 cannot receive the paging signal becomes high. Thus, the base station 110 can use the beam selected by the terminal 101 during location registration and one or more beams associated with this beam as the first beam. For example, the base station 110 can associate one or more beams composed of a predetermined number of beams (for example, selected in order from those with a close spatial distance between beams) formed spatially near the beam selected by the terminal 101 during location registration, and determine them as the first beam. By transmitting a paging signal using the beam selected by the terminal 101 during location registration and the surrounding beams, the possibility that the terminal 101 can receive the paging signal can be increased. Also, by performing paging using only a part of the many beams that the base station 110 can form, compared with performing paging using all beams, the number of slots in which paging occasions are set can be reduced, so that frequency resources can be effectively utilized. Also, the base station 110 can determine the beam selected by the terminal 101 during location registration and one or more beams pre-associated with this as the first beam. For example, the base station 110 can create a group of a plurality of pre-associated beams in advance, and can determine the group including the beam selected by the terminal 101 during location registration as the first beam. A group of beams composed of a plurality of beams can be called a beam set. As an example, a beam set can be composed of a plurality of beams whose coverage partially overlaps. Also, a beam set can be composed of a plurality of beams detected in measurements performed by the terminal 101 (for example, measurements of RSRP and RSRQ during location registration, etc.). Furthermore, a beam set can be composed of a plurality of beams designed to include a predetermined geographical location in the coverage.Also, the beam set can be composed of a plurality of beams with high correlation in the location registration history of the terminal 101. For example, when the terminal 101 performs location registration using a specific beam, other beams used in location registration within a certain period before and after that can be selected as beams with high correlation with that specific beam. In this case, not only the location registration history of one terminal 101 but also the location registration histories of a plurality of terminals 101 can be used. Note that the beam set may be composed of a determined combination of beams by an operator of a network or system, etc. By associating a plurality of beams in advance, it becomes possible to select beams promptly compared to the case of dynamically associating a plurality of beams, and the computational load at the base station 110 can also be reduced.

[0020] When the base station 110 satisfies a predetermined condition, it distributes a paging signal using only the first beam. When the terminal 101 is a terminal without movement (a terminal with a fixed position), even if the beam for distributing the paging signal is limited, the paging signal is likely to be received. On the other hand, when the terminal 101 is a terminal with movement, limiting the beam for distributing the paging signal increases the possibility of failure to receive the paging signal. Therefore, the base station 110 sets as a predetermined condition that it is within a predetermined period after identifying the first beam, and when this condition is satisfied, it can distribute a paging signal using only the first beam. Even if the terminal 101 is a terminal with movement, within a certain period after the base station 110 acquires information from the terminal 101, the terminal 101 is likely to be within the area covered by the first beam. Therefore, by distributing a paging signal using only the first beam only within the period when the terminal 101 is likely to be present, the base station 110 can reduce the number of slots in which a paging occasion is set while maintaining the possibility that the terminal 101 can receive the paging signal. For example, the base station 110 can identify the first beam based on the beam associated with the RACH used for random access when the terminal 101 performs random access for location registration. Also, when the terminal 101 periodically measures beams and notifies the measurement results to the base station 101, the base station 101 can identify the first beam based on this measurement result. When the base station 110 transmits a paging signal using a beam set, it can determine the beam set associated with the identified beam as the first beam. Note that the base station 110 may set as a predetermined condition that it is within a predetermined period after the location registration of the terminal 101 is completed. The base station 110 is not limited to these, and can set as a predetermined condition that it is within a certain time after the terminal 101 notifies the base station 110 of the information of the beam it captures.

[0021] The predetermined conditions are not limited to the above, and other methods may be used. For example, when information on a specific one beam is notified from the terminal 101 for a predetermined number of consecutive times (for example, when the terminal 101 performs location registration using a specific one beam), it may be considered that the predetermined conditions are satisfied. When a specific one beam is continuously selected for a predetermined number of times, the possibility that the terminal 101 is a terminal without movement increases. By distributing a paging signal using only the first beam to such a terminal 101, it becomes possible to effectively utilize frequency resources while suppressing the possibility that the terminal 101 cannot receive the paging signal. When the base station 110 distributes a paging signal using a beam set, it may be considered that the predetermined conditions are satisfied when any of the plurality of beams included in one beam set is used for location registration continuously for a predetermined number of times, or when it is reported as the optimal beam based on the measurement of the terminal 101. For example, in FIG. 1, when the beam set is composed of beams 141 to 143, if the terminal 101 performs location registration continuously for a predetermined number of times while moving between these beams, the predetermined conditions are satisfied, and this beam set can be selected as the first beam. Thereby, even when the mobility of the terminal 101 is not high and it moves between a plurality of beams within one beam set, the present technology can be applied and the resource utilization efficiency can be improved. Further, when the position estimation of the terminal 101 is periodically performed, the base station 110 may use, as the predetermined condition, that it is within a certain period after this position estimation is performed, or that the change in the position of the terminal 101 is within a predetermined range (for example, the result of each position estimation is included in a circle with a predetermined radius) for a predetermined number of consecutive times. For the position estimation of the terminal 101, TDOA (Time Difference of Arrival), AoA (Angle of Arrival), AoD (Angle of Departure), etc. may be used. Also, GNSS (Global Navigation Satellite System) etc. may be used as the position estimation method. Note that the base station 110 may use a combination of the above predetermined conditions.By combining a plurality of conditions, it becomes possible to surely deliver a paging signal to the terminal 101.

[0022] FIG. 6 shows a sequence example when the base station 110 determines a predetermined condition and distributes a paging signal to the terminal 101 using the first beam. Here, it is assumed that the registration of the location information in the AMF 121 has been completed for the terminal 101, and the terminal 101 is performing an intermittent reception operation while periodically updating the location information. Regarding the location registration of the terminal 101, for the same processing as in FIG. 2, the same reference numbers are assigned and the description is omitted. First, when the timer based on the T3512 value indicated by the AMF 121 expires in the registration acceptance, the terminal 101 notifies the AMF 121 of the information on the TA in which it is located. The procedures S201 to S206 for the terminal 101 to perform periodic registration updates are the same as the procedures shown in FIG. 2. The base station 110 transmits a synchronization signal and notification information using each beam formed by the self-device, and the terminal 101 measures the signals transmitted in each beam and selects an optimal beam (S201). Subsequently, the terminal 101 executes a random access procedure (S202) using the RACH corresponding to the selected beam, accesses the base station 110, and requests an update of the location information (S203 to S206). The procedure for updating the location registration of the terminal 101 is the same as in FIG. 2, so the description is omitted. On the other hand, the base station 110 identifies and stores the beam selected by the terminal 101 based on the RACH used by the terminal 101. Further, the base station 110 determines and stores the first beam based on this beam. Then, when data destined for the terminal 101 is generated (S601), the AMF 121 issues a paging request to the base station 110 based on the registered location information of the terminal 101 (S602). The base station 110 determines whether or not a predetermined condition is satisfied for the first beam for the terminal 101 stored in the self-device (S603). For example, the base station 110 can determine whether or not a predetermined condition is satisfied by evaluating whether or not the time elapsed since the first beam was determined is within a threshold value. When the predetermined condition is satisfied, the base station 110 distributes a paging signal using only the first beam (S607). On the other hand, the terminal 101 is performing an intermittent reception operation (S604 to S606), and receives a paging signal (RRC Paging) transmitted from the base station 110 in the paging occasion of S606.Since the sequence after the terminal 101 receives the paging signal is the same as the sequence after S303 in FIG. 3, the description thereof is omitted.

[0023] On the other hand, when a predetermined condition is not satisfied, the base station 110 can transmit a paging signal using the first beam and the second beam. For example, when a certain period of time has elapsed since the terminal 101 performed location registration, it is highly likely that the terminal 101 has moved outside the coverage of the first beam. In this case, if the paging signal is distributed using only the first beam, there is a high possibility that the terminal 101 cannot receive the paging signal. Therefore, when a predetermined condition is not satisfied, the base station 110 can transmit a paging signal using all the beams including the second beam. This increases the possibility that the terminal 101 can receive the paging signal. Also, even when a predetermined condition is satisfied, if the base station 110 does not receive a response (for example, a NAS message including a service request) to the paging signal from the terminal 101 within a predetermined period as a result of performing the distribution of the paging signal using only the first beam, the base station 110 can transmit (or retransmit) the paging signal using the first beam and the second beam. This makes it possible to promptly notify the terminal 101 of the paging signal even when the terminal 101 has moved outside the coverage of the first beam. For example, the base station 110 can transmit the paging signal using the first beam and the second beam when, after performing the distribution of the paging signal using only the first beam, no response is received even after repeatedly transmitting the paging signal over a plurality of paging occasions.

[0024] Note that the base station 110 may perform paging signal distribution using only the first beam based on the notification from the AMF 121. For example, depending on the communication traffic and resource utilization status in the cell provided by the base station 110, the priority order between reliably notifying the paging signal and suppressing the resource usage due to the paging signal distribution may change. Also, due to the location where the base station 110 is deployed, updates to the network and system operation policies, etc., the priority order between reliably notifying the paging signal for each base station 110 and suppressing the resource usage due to the paging signal distribution may change. In response to such differences and changes in the situation, the AMF 121 notifies the base station 110 whether to permit the distribution of the paging signal using only the first beam. Thereby, it becomes possible to effectively utilize the frequency resources while considering the operational priorities of the network and system. Also, instead of the base station 110, the AMF 121 can determine whether a predetermined condition for distributing the paging signal using only the first beam is satisfied. By the AMF 121 determining whether the predetermined condition is satisfied, the processing load for the base station 110 to individually perform condition determination can be reduced. Also, when the condition is changed when performing determination using the same condition throughout the network and system, or when performing determination by setting different conditions for each individual base station 110, the procedure for notifying each base station 110 of the condition change or setting can be omitted. Also, by the AMF 121 determining whether the predetermined condition is satisfied, as will be described later, it becomes possible to determine the predetermined condition across a plurality of base stations 110. Hereinafter, an example in which the base station controls the distribution of the paging signal based on the notification from the AMF 121 will be described.

[0025] First, it is determined whether or not a predetermined condition for the distribution of a paging signal using only the first beam is satisfied by the AMF 121. Based on the determination result, an example in which the base station 110 controls the distribution of the paging signal will be described. FIG. 7 shows a sequence example when the AMF 121 determines a predetermined condition and instructs the base station 110 to distribute a paging signal to the terminal 101 using the first beam. Similar to FIG. 6, it is assumed that the terminal 101 has completed the registration of position information in the AMF 121 and is performing an intermittent reception operation while periodically updating the position information. Regarding the same processing as in FIG. 6, the same reference numerals are given and the description is omitted. In FIG. 7, the sequences up to S201 to S205 are the same as in FIG. 6. That is, the base station 110 identifies the beam selected by the terminal 101 based on the RACH used by the terminal 101 (S202). Then, the base station 110 notifies the AMF 121 of a message including the information of the identified beam (S701). For example, the base station 110 can notify the AMF 121 by including information (such as tci-StateId, qci-Type, ssb index, etc.) for identifying the beam in the NG-AP's Initial UE Message for updating the position information of the terminal 101. The AMF 121 can store the received beam information and use it for determining whether or not a predetermined condition is satisfied. Note that the method by which the base station 110 notifies the AMF 121 of the information of the identified beam is not limited to the Initial UE Message, and for example, a new message may be defined. Also, the information for identifying the beam is not limited to tci-StateId, qci-Type, and ssb index, and may have another name. Further, the base station 110 may identify the first beam based on the beam selected by the terminal 101 and notify the AMF 121. In this case, the AMF 121 can determine whether or not a predetermined condition is satisfied based on the first beam notified by the base station 110. Here, when data destined for the terminal 101 is generated (S601), the AMF 121 determines whether or not a predetermined condition is satisfied based on the beam information of the terminal 101 stored in its own device (S702).For example, the determination of the predetermined condition in the AMF 121 may be the same as the determination of the predetermined condition in the base station 110 described above. When the AMF 121 determines that the predetermined condition is satisfied, it instructs the base station 110 to distribute a paging signal using only the first beam (S703). For example, the AMF 121 may include an instruction to distribute a paging signal using only the first beam in the NG-AP's Paging request for making a paging request to the base station 110. As an example, the AMF 121 may implicitly notify the instruction by including information (such as tci-StateId, qci-Type, ssb index, etc.) for specifying the first beam in the Paging request. Further, the AMF 121 may notify an explicit instruction separately from the information for specifying the first beam. Note that the method by which the AMF 121 notifies the instruction to the base station 110 is not limited to the Paging request, and for example, a new message may be defined in the NG-AP. Also, the information for specifying the first beam is not limited to tci-StateId, qci-Type, ssb index, etc., and may have another name. When the base station 110 receives an instruction from the AMF 121, it executes the distribution of the paging signal according to the instruction. Since the operations after S604 are the same as those in FIG. 6, the description thereof is omitted. Note that the AMF 121 may instruct the base station 110 to distribute a paging signal using only the first beam, and the base station 110 may determine the first beam and distribute the paging signal. Thereby, the processing load for the AMF 121 to individually determine the first beam for all the terminals 101 is reduced. Also, even when the AMF 121 determines the first beam, the notification of the first beam from the AMF 121 to the base station 110 and the instruction to determine the first beam and distribute the paging signal may be performed at different timings. In this case, the AMF 121 may notify the corresponding base station 110 each time it determines the first beam. Further, when making a paging request to each base station 110, the AMF 121 may give an instruction as to whether to distribute a paging signal using only the first beam.When the base station 110 that has received an instruction from AMF121 forms a first beam associated with the terminal 101 that is the target of paging, it distributes a paging signal using this first beam. On the other hand, when the base station 110 does not form a first beam associated with the terminal 101 that is the target of paging, it may not distribute the paging signal.

[0026] When the AMF 121 determines the first beam, the AMF 121 may determine the first beam by combining the beams formed by each of the plurality of base stations 110. For example, when the base station 111 and the base station 112 in FIG. 1 are arranged close to each other geographically, a part of the coverage of the beams formed by each base station may overlap. In this case, the AMF 121 combines the beams of the plurality of base stations 110 to form a beam set, requests each base station 110 to distribute a paging signal using only the first beam, and may specify the first beam included in the beam formed by each base station. As a result, the paging signal is distributed using more beams, increasing the likelihood that the terminal 101 can receive the paging signal. In the case of FIG. 1, the AMF 121 may form a beam set including, for example, beam 141 and beam 144. As an example, the AMF 121 may create a beam set of a plurality of pre-associated beams in advance and determine, as the first beam, the beam set including the beam selected by the terminal 101 during location registration. As an example, the beam set set by the AMF 121 may be composed of a plurality of beams whose coverage partially overlaps each other. Further, the beam set may be composed of a plurality of beams detected in the measurement performed by the terminal 101 (for example, measurement of RSRP and RSRQ during location registration). For example, the terminal 101 at a specific location measures the SSS transmitted in each beam of each base station 110 and provides the AMF 121 with information on the beams exceeding a predetermined threshold. The AMF 121 may perform association of a plurality of beams using the measurement results by the terminal 101. Furthermore, the beam set may be composed of a plurality of beams designed to include a predetermined geographical location in the coverage. For example, the AMF 121 may form a beam set based on the geographical location of each base station 110 and the direction of the beam formed by that base station 110. Also, the beam set may be composed of a plurality of beams having a high correlation in the location registration history of the terminal 101. When the coverage of the beams formed by the plurality of base stations 101 overlaps, even if the movement distance of the terminal 101 is small, different base stations 110 may be used every time the location information is updated.When AMF121 forms a beam set by combining beams formed by a plurality of base stations 110, even when the terminal 101 moves across the base stations 110, if it is a movement between beams within one beam set, this technology can be applied and the resource utilization efficiency can be improved. For example, AMF121 may consider that a predetermined condition is satisfied when any of a plurality of beams formed by different base stations 110 included in one beam set is used for location registration continuously for a predetermined number of times.

[0027] AMF121 may send a notification to the base station 110 permitting the distribution of a paging signal using only the first beam. For example, AMF121 may send a notification permitting the distribution of a paging signal using only the first beam when the communication traffic or resource utilization rate exceeds a threshold in the cell provided by the base station 110. The base station 110 that receives this notification will send a paging signal using only some of the beams that the device can form when a predetermined condition is satisfied. Thus, it becomes possible to transmit a data signal or the like using the resources released from the distribution of the paging signal. Also, AMF121 may send a notification permitting the distribution of a paging signal based on a request from the base station 110. For example, the base station 110 may send a request to AMF121 when it detects that the communication traffic or resource utilization rate exceeds a threshold in the cell provided by the device. Further, AMF121 may send a notification uniformly permitting or prohibiting the distribution of a paging signal using only the first beam to all or some of the base stations 110 connected to the device itself. This enables the execution of control reflecting network operation policies such as switching between reliably notifying the paging signal and efficiently using resources while delegating the determination of whether to distribute a paging signal using only the first beam for each base station 110. The notification from AMF121 can be distributed by an NG-AP message.

[0028] When AMF121 meets the predetermined conditions for the distribution of paging signals using only the first beam, it can send a paging request only to the base station 110 that forms this first beam. As a result, other base stations 110 included in the same TAI do not need to send paging signals, so it becomes possible to effectively utilize resources as a whole network. On the other hand, even when the predetermined conditions are met, AMF121 can notify a paging request to all base stations 110 included in the TAI. In this case, when the base station 110 can form the first beam for the terminal 101 to be paged, it can perform the distribution of the paging signal using only the first beam. When it cannot form the first beam, it may perform the distribution of the paging signal using all the beams that the device itself can form, or it may not perform the distribution of the paging signal. Thereby, when the number of base stations 110 connected to AMF121 is large, the processing load for AMF121 to identify the base station 110 to which the paging request is to be sent is reduced. Note that AMF121 may limit the base station 110 to which the paging request is to be sent using conditions different from the predetermined conditions for the distribution of paging signals using only the first beam. By separately setting the conditions for distributing paging signals using only the first beam and the conditions for limiting the base station 110 to which the paging request is notified, it becomes possible to flexibly adjust ensuring the notification of paging signals and effectively utilizing resources. For example, AMF121 can send a paging request only to the base station 110 that performs the distribution of the paging signal using only the first beam when it is within a certain period after the location registration of the terminal 101 is completed. Also, when a specific one base station 110 has been the connection destination during the location registration of the terminal 101 for a predetermined number of consecutive times (for example, when the same NR CGI is received), AMF121 can make a paging request only to this specific one base station 110. Since a specific one base station 110 is continuously selected for a predetermined number of times, the possibility that the terminal 101 is a terminal without movement becomes high, so the possibility of receiving paging can be maintained. Note that AMF121 can use a combination of the above-mentioned predetermined conditions.By combining multiple conditions, it becomes possible to surely deliver a paging signal to the terminal 101. Further, among a plurality of base stations 110 that distribute a paging signal using only the first beam, when the communication traffic volume and the resource usage amount in the cells provided by some of them exceed a predetermined threshold, the AMF 121 may not issue a paging request to that base station 110. As a result, distribution of the paging signal and exchange of messages with the terminal 101 are executed using base stations other than this base station 110. Therefore, an increase in the communication traffic load in this base station 110 can be avoided. (Circuit Configuration) Next, a configuration example of the base station 110 and the AMF 121 as described above will be described. FIG. 8 is a diagram showing the hardware configuration of the base station 110 and the AMF 121. The base station 110 and the AMF 121 are configured to include, in one example, a processor 801, a ROM 802, a RAM 803, a storage device 804, and a communication circuit 805. The processor 801 is a computer including one or more processing circuits such as a general-purpose CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit). The processor 801 reads and executes programs stored in the ROM 802 and the storage device 804 to execute the overall processing of the device and each of the above-described processes. The ROM 802 is a read-only memory in which information such as programs and various parameters related to the processes executed by the base station 110 and the AMF 121 are recorded. The RAM 803 functions as a work space when the processor 801 executes a program, and is a random access memory in which temporary information is recorded. The storage device 804 is configured by, for example, a removable external storage device or the like. The communication circuit 805 is configured to include, for example, a circuit for communicating with other devices. (Functional Configuration) FIG. 9 is a diagram showing a functional configuration example of the base station 110. The base station 110 includes, as its functions, for example, a beam forming unit 901, a beam specifying unit 902, a paging control unit 903, and an information communication unit 904. FIG. 9 shows the functional configuration of the base station 110 according to the present embodiment, and for example, the general configuration of the base station is omitted. These functional units can be realized, for example, by a processor 801 executing programs stored in a ROM 802 and a storage device 804 and controlling a communication circuit 805 as necessary. However, the present invention is not limited to this, and for example, dedicated hardware for realizing each function may be provided.

[0029] The beam forming unit 901 forms a plurality of beams that cover different areas. For example, the beam forming unit 901 can form a plurality of beams by controlling a plurality of antennas (not shown) connected to the communication circuit 805. Also, the beam forming unit 901 uses the formed beams to transmit signals such as synchronization signals and notification information, and to transmit and receive signals (paging signals, RRC messages, data, etc.) with the terminal 101. The beam identification unit 902 identifies the first beam. For example, the beam identification unit 902 can identify the optimal beam with the terminal 101 based on the RACH received by the beam forming unit 901 from the terminal 101. Also, the beam identification unit 902 can identify the first beam by one or more beams (beam sets, etc.) associated with this beam. The paging control unit 903 controls the distribution of paging signals. For example, the paging control unit 903 determines whether a predetermined condition is satisfied, and if the predetermined condition is satisfied, it transmits a paging signal using the first beam and controls the beam forming unit 901 so as not to distribute the paging signal using the second beam. Also, when the predetermined condition is not satisfied, the paging control unit 903 controls the beam forming unit 901 to distribute the paging signal using the first beam and the second beam. The paging control unit 903 can control the distribution of paging signals based on the notification from the AMF 121 received by the information communication unit 904. For example, the paging control unit 903 can execute the determination of whether a predetermined condition is satisfied only when there is permission from the AMF 121. Also, when receiving an instruction from the AMF 121, the paging control unit 903 can control the beam forming unit 901 to execute the distribution of the paging signal using only the first beam. The information communication unit 904 executes communication with the AMF 121 via the communication circuit 805. For example, the information communication unit 904 notifies the AMF 121 of information identifying the beam corresponding to the RACH used by the terminal 101. Also, the information communication unit 904 receives a notification for controlling the distribution of paging signals from the AMF 121. For example, the information communication unit 904 can receive a permission notification from the AMF 121 indicating that the distribution of the paging signal using only the first beam may be performed.In addition, the information communication unit 904 may receive an instruction from the AMF 121 to distribute a paging signal using only the first beam. Further, the information communication unit 904 may receive information identifying the first beam from the AMF 121.

[0030] FIG. 10 is a diagram showing a functional configuration example of the AMF 121. The AMF 121 includes, as its functions, for example, an information notification unit 1001, an information acquisition unit 1002, a beam identification unit 1003, and a condition determination unit 1004. FIG. 10 shows the functional configuration of the AMF 121 in the present embodiment, and for example, the general configuration of the AMF is omitted. Note that these functional units can be realized, for example, by the processor 801 executing programs stored in the ROM 802 and the storage device 804 and controlling the communication circuit 805 as necessary. However, it is not limited thereto, and for example, dedicated hardware for realizing each function may be prepared.

[0031] The information notification unit 1001 notifies, via the communication circuit 805, a paging request to the base station 110 and a notification for controlling the distribution of the paging signal. For example, based on the determination result of the condition determination unit 1004, the information notification unit 1001 may notify the base station 110 of an instruction on whether to execute the distribution of the paging signal using only the first beam. In addition, the information notification unit 1001 may notify the base station 110 of the first beam identified by the beam identification unit 1003. Further, the information notification unit 1001 may notify the base station 110 of permission to execute the distribution of the paging signal using only the first beam. The information acquisition unit 1002 acquires, from the base station 110, information identifying the beam corresponding to the RACH used by the terminal 101. The beam identification unit 1003 determines the first beam based on the information identifying the beam acquired by the information acquisition unit 1002. The condition determination unit 1004 determines whether a predetermined condition for distributing the paging signal using only the first beam is satisfied. The condition determination unit 1004 may notify the determination result to the base station 110 via the information notification unit 1001.

[0032] As described above, according to this embodiment, between the base station 110 capable of forming a plurality of beams and the terminal 101, one or more first beams specified corresponding to the position when the position registration of the terminal 101 is performed are specified. Then, when a predetermined condition is satisfied, the base station 110 transmits a paging signal using the first beam, and executes paging signal distribution control so as not to distribute a paging signal using a second beam different from the first beam. Thereby, the base station 110 can transmit a paging signal using only the beam selected by the terminal 101 as an optimal beam. For this reason, since the slots in which paging occasions are set to transmit paging signals are significantly reduced, it becomes possible to efficiently use frequency resources. Also, when a predetermined condition is satisfied, the above-described paging signal distribution control is executed. For this reason, since the possibility of receiving a paging signal can be maintained, it becomes possible to effectively use frequency resources while suppressing deterioration of communication quality. Therefore, it becomes possible to contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, "Build resilient infrastructure, promote sustainable industrialization, and foster innovation."

[0033] The invention is not limited to the above embodiment, and various modifications and changes are possible within the scope of the gist of the invention.

Description of Reference Numerals

[0034] 101: Terminal, 111: Base Station, 112: Base Station, 113: Base Station, 114: Base Station, 115: Base Station, 121: AMF

Claims

1. A base station capable of forming a plurality of beams with a common Tracking Area Code defined in the cellular communication standard of the Third Generation Partnership Project (3GPP), a specifying means for specifying one or more of the first beams included in the plurality of beams, the one or more first beams being specified corresponding to a position at the time of location registration of a terminal, a control means for controlling the distribution of paging signals, the control means performing the control of distributing the paging signals using the first beam and not distributing the paging signals using a second beam different from the first beam when a predetermined condition is satisfied. The base station is characterized by the above.

2. The base station further includes a notification means for notifying a network device of any one or more of the position information at the time of location registration of the terminal, information indicating a beam used at the time of location registration of the terminal, or information indicating the first beam specified by the specifying means. The base station according to claim 1, characterized by the above.

3. The specifying means acquires information for designating the first beam from a network device. The base station according to claim 1, characterized by the above.

4. When the predetermined condition is not satisfied, the control means performs the control of distributing the paging signals using the first beam and the second beam. The base station according to any one of claims 1 to 3, characterized by the above.

5. When the control means receives an instruction from a network device that it should perform the control of distributing the paging signals using the first beam and not distributing the paging signals using the second beam, the control means performs the control. The base station according to claim 1, characterized by the above.

6. The control means determines whether the predetermined condition is satisfied, and when the predetermined condition is satisfied, the control means performs the control of distributing the paging signals using the first beam and not distributing the paging signals using the second beam. The base station according to claim 1, characterized by the above.

7. When any one or more of the following conditions are met, the control means determines that the predetermined condition is satisfied: the time elapsed since the identification of the first beam is shorter than a predetermined threshold value; the position registration of the terminal has been performed using a specific one beam for a predetermined number of consecutive times; or the change in the position information of the terminal has been detected within a predetermined range over a predetermined period or for a predetermined number of consecutive times. The base station according to claim 6, characterized in that.

8. When the control means receives permission from the network to execute the control of distributing the paging signal using the first beam and not distributing the paging signal using the second beam from the network device, the control means makes the determination. The base station according to claim 6 or 7, characterized in that.

9. A network device that communicates with a base station capable of forming a plurality of beams having a common tracking area code defined in the cellular communication standard of the Third Generation Partnership Project (3GPP) and operates as an Access and Mobility Function, including notification means for notifying the base station to execute predetermined control of distributing the paging signal when a predetermined condition is satisfied, wherein the predetermined control is to distribute the paging signal using one or more first beams determined from among the plurality of beams based on the position information at the time of position registration of the terminal and not to distribute the paging signal using a second beam different from the first beam among the plurality of beams. The network device is characterized in that.

10. further comprising acquisition means for acquiring information indicating the first beam specified by the base station from the base station. The network device according to claim 9, characterized in that.

11. acquisition means for acquiring any one or more of the position information at the time of position registration of the terminal or information indicating the beam used at the time of position registration of the terminal from the base station; further comprising specifying means for specifying the first beam using the position information at the time of position registration of the terminal or information indicating the beam used at the time of position registration of the terminal; and the notification means performs the notification including information indicating the first beam specified by the specifying means. The network device according to claim 9, characterized in that...

12. further comprising determination means for determining whether or not the predetermined condition is satisfied, wherein the notification means, when the predetermined condition is satisfied, performs notification including an instruction for causing the base station to perform control to distribute the paging signal using the first beam and not to distribute the paging signal using the second beam, and when the predetermined condition is not satisfied, performs notification including an instruction for causing the base station to perform control to distribute the paging signal using the first beam and the second beam The network device according to claim 9, characterized in that...

13. the determination means determines that the predetermined condition is satisfied when any one or more of the following are satisfied: the time elapsed since the first beam was specified is shorter than a predetermined threshold value; terminal location registration has been performed using a specific one beam for a predetermined number of consecutive times; or it has been detected that the change in the location information of the terminal is within a predetermined range over a predetermined period or for a predetermined number of consecutive times The network device according to claim 12, characterized in that...

14. A communication method executed by a base station capable of forming a plurality of beams, wherein the tracking area codes defined in the cellular communication standard of the 3rd Generation Partnership Project (3GPP) are common, a specifying step of specifying one or more of the first beams included in the plurality of beams, the first beam being specified corresponding to the location at the time of terminal location registration; a control step of a control means for controlling the distribution of a paging signal, the control step performing control to distribute the paging signal using the first beam and not to distribute the paging signal using a second beam different from the first beam when a predetermined condition is satisfied A communication method, characterized in that...

15. A communication method executed by a network device that communicates with a base station capable of forming a plurality of beams having common tracking area codes defined in the cellular communication standard of the 3rd Generation Partnership Project (3GPP) and operates as an Access and Mobility Management Function including a notification step of notifying the base station to perform predetermined control of paging signal distribution when a predetermined condition is satisfied; wherein the predetermined control is to perform paging signal distribution using one or more first beams determined from among the plurality of beams based on position information at the time of terminal location registration, and not to perform paging signal distribution using a second beam different from the first beam among the plurality of beams; A communication method characterized by the above.

16. In a computer provided in a base station capable of forming a plurality of beams that share a tracking area code defined in the cellular communication standard of the Third Generation Partnership Project (3GPP), identifying one or more of the first beams included in the plurality of beams, the first beams being identified corresponding to the position at the time of terminal location registration; a control means for controlling the distribution of paging signals, which, when a predetermined condition is satisfied, causes the above control to be performed, that is, to perform paging signal distribution using the first beam and not to perform paging signal distribution using a second beam different from the first beam; A program for this purpose.

17. In a computer provided in a network device that communicates with a base station capable of forming a plurality of beams that share a tracking area code defined in the cellular communication standard of the Third Generation Partnership Project (3GPP) and operates as an Access and Mobility Management Function, a program for causing the base station to be notified to perform predetermined control of paging signal distribution when a predetermined condition is satisfied, wherein the predetermined control is to perform paging signal distribution using one or more first beams determined from among the plurality of beams based on position information at the time of terminal location registration, and not to perform paging signal distribution using a second beam different from the first beam among the plurality of beams; A program.

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