Communication management device and communication management method

Abstract

A communication management device according to the present invention manages a plurality of tracking areas including a communication area of at least one base station from among a plurality of base stations, and a plurality of tracking area lists that each include at least one tracking area from among the plurality of tracking areas. A first determination unit determines a tracking area list to which each of the plurality of base stations belongs by obtaining a first solution that satisfies at least one of: minimization of the number of transmission of a paging signal in each of the plurality of tracking area lists; and minimization of the number of transmissions of a position registration signal transmitted when a communication terminal has moved between base stations belonging to different tracking area lists. A second determination unit determines a tracking area to which a base station belonging to one tracking area list belongs by obtaining a second solution that satisfies minimization of the number of transmissions of a paging signal in the one tracking area list.

Description

Communication management device and communication management method

[0001] The present invention relates to a communication management device and a communication management method.

[0002] Conventionally, calling (paging) of a communication terminal is performed using a tracking area (TA) and a tracking area list (TA-List). For example, Patent Document 1 below discloses a method for providing a communication terminal with a tracking area list according to its mobility characteristics. An area number acquisition means references a history information storage means and acquires the number of tracking areas in which the terminal has been present within a predetermined time period. A determination means determines whether the acquired number of tracking areas is equal to or greater than a threshold. If it is determined that the number of tracking areas is equal to or less than the threshold, a list generation means generates a first tracking area list based on the tracking areas stored in the history information storage means. If it is determined that the number of tracking areas is equal to or less than the threshold, a transmission means transmits the first tracking area list to the terminal. If it is determined that the number of tracking areas is greater than the threshold, a transmission means transmits a second tracking area list to the terminal.

[0003] Japanese Patent Application Laid-Open No. 2022-003719

[0004] In order to reduce the number of paging signals sent when a communication terminal is called, efforts are being made to optimize the tracking area to which a base station belongs and the tracking area list. However, in the optimization problem described above, quadratic and cubic terms are included in the objective function, and the problem scale increases in proportion to the number of base stations.

[0005] An object of the present invention is to efficiently optimize the tracking area to which a base station belongs and the tracking area list.

[0006] a first determination unit that determines to which of the plurality of tracking area lists each of the plurality of base stations belongs; and a second determination unit that determines to which of the at least one tracking area included in the one tracking area list a base station belonging to one of the plurality of tracking area lists belongs, wherein the first determination unit determines the tracking area list to which each of the plurality of base stations belongs by finding a first solution that satisfies at least one of minimizing the number of paging signal transmissions in each of the plurality of tracking area lists and minimizing the number of location registration signal transmissions that are transmitted when a communication terminal moves between base stations that belong to different tracking area lists; and the second determination unit determines the tracking area to which the base station belonging to the one tracking area list belongs by finding a second solution that satisfies minimizing the number of paging signal transmissions in the one tracking area list.

[0007] A communication management method according to one embodiment of the present invention manages a plurality of tracking areas including a communication area of ​​at least one base station among a plurality of base stations and a plurality of tracking area lists including at least one of the plurality of tracking areas, determines a tracking area list to which each of the plurality of base stations belongs by finding a first solution that satisfies at least one of minimizing the number of transmissions of all paging signals in each of the plurality of tracking area lists and minimizing the number of transmissions of location registration signals transmitted when a communication terminal moves between base stations belonging to different tracking area lists, and determines a tracking area to which a base station belonging to one tracking area list belongs by finding a second solution that satisfies minimizing the number of transmissions of paging signals in one tracking area list among the plurality of tracking area lists.

[0008] According to one aspect of the present invention, it is possible to efficiently optimize the tracking area to which a base station belongs and the tracking area list.

[0009] FIG. 1 is a schematic diagram showing a communication system 1 managed by a communication management device 10 according to an embodiment. FIG. 1 is a schematic diagram showing a paging method in the communication system 1. FIG. 1 is a schematic diagram showing a paging method in the communication system 1. FIG. 1 is a schematic diagram showing a location registration signal RS. FIG. 1 is a schematic diagram showing an example of first determination information. FIG. 2 is a block diagram showing the configuration of the communication management device 10. FIG. 2 is a diagram showing a schematic relationship between the position of a base station S and a tracking area TA. FIG. 3 is a table showing the belonging of a tracking area TA of a base station S. FIG. 3 is a table showing the belonging of a tracking area TA of a base station S. FIG. 4 is a flowchart showing the operation of a processing device 105 of the communication management device 10. FIG. 4 is a block diagram showing the configuration of a communication management device 10A according to a first modified example.

[0010] A. Embodiment A-1. Overall Configuration Fig. 1 is a schematic diagram showing a communication system 1 managed by a communication management device 10 according to an embodiment. The communication system 1 is a wireless communication system using, for example, LTE (Long Term Evolution). The communication system 1 includes a communication terminal 20, an MME (Mobility Management Entity) 30, and multiple base stations S (S1 to S5 are shown in Fig. 1).

[0011] The communication terminal 20 is a mobile terminal such as a smartphone, an in-vehicle device, or an IoT (Internet of Things) device. The communication terminal 20 may also be referred to as a user equipment (UE).

[0012] The base stations S constitute a radio access network (RAN) in the communication system 1 that performs wireless communication with the communication terminals 20. The base stations S may also be referred to as eNBs (evolved Node Bs). The base stations S (S1 to S5) shown in FIG. 1 wirelessly communicate with the communication terminals 20 located within their respective communication areas E (E1 to E5) called cells. In the RAN, the communication areas E of the many base stations S form the communication area of ​​the network. In this embodiment, only a few base stations S are shown, but in reality, hundreds to thousands of base stations S are deployed in the communication system 1.

[0013] The MME 30 is a node that constitutes a control plane (C-Plane) in the core network (CN) of the communication system 1. The MME 30 and each base station S are connected by a line called a backhaul. In FIG. 1 , the connection between the MME 30 and each base station S is omitted from the illustration. The MME 30 performs various controls in the communication system 1, such as registering the communication terminal 20 in the core network and managing the mobility of the communication terminal 20.

[0014] 2 to 4 are schematic diagrams illustrating a paging method in communication system 1. The upper parts of FIGS. 2 to 4 schematically show communication areas E1 to E9 of base stations S1 to S9. As shown by the dotted lines, it is assumed that communication terminal 20 was located in communication area E5 of base station S5 when the previous incoming call ended (when the call ended). In other words, the base station S last accessed by communication terminal 20 is base station S5. Meanwhile, as shown by the solid lines, it is assumed that communication terminal 20 is currently located in communication area E1 of base station S1.

[0015] The lower parts of Figures 2 to 4 schematically show tracking areas TA to which base stations S1 to S9 belong. In the example shown in the figures, tracking area list L1 (denoted as "TA-List1" in the figures) includes tracking areas TA1 to TA3. Tracking area TA1 contains base stations S1 to S3. In other words, base stations S1 to S3 belong to tracking area TA1. Base stations S1 to S3 belong to tracking area list L1. Furthermore, tracking area TA2 contains base stations S4 to S6. Tracking area TA3 contains base stations S7 to S9.

[0016] Here, a case where an incoming call request is made to the communication terminal 20 will be considered. The incoming call request includes, for example, receiving a message using a message application and a push notification from a social networking service (SNS) application or the like. When an incoming call request is made to the communication terminal 20, the MME 30 first causes a paging signal to be transmitted from the base station S5 last accessed by the communication terminal 20 (see FIG. 2 ). Hereinafter, the transmission of a paging signal from the base station S5 last accessed by the communication terminal 20 will be referred to as a “first paging,” and the paging signal transmitted in the first paging will be referred to as a “first paging signal.” The “first paging” may also be referred to as a “first paging (initial paging).” The “first paging signal” may also be referred to as a “first paging signal.” In the example shown in FIG. 2 , the communication terminal 20 is not located in the communication area E5 of the base station S5, so the incoming call request by the first paging signal fails.

[0017] If the call reception request by the first paging signal fails, the MME 30 causes all base stations S belonging to the tracking area TA to which the base station S5 (the base station S that transmitted the first paging signal) belongs to transmit paging signals (see FIG. 3 ). Hereinafter, transmitting paging signals from all base stations S in the tracking area TA to which the base station S that transmitted the first paging signal belongs will be referred to as "second paging," and the paging signal transmitted in the second paging will be referred to as "second paging signal." The term "second paging" may also be referred to as "retransmission paging." The term "second paging signal" may also be referred to as "retransmission paging signal." In the example shown in FIG. 3 , the base station S5 belongs to the tracking area TA2. Therefore, the second paging signal is transmitted to the communication areas E4 to E6 of the base stations S4 to S6. In the example shown in FIG. 3 , the communication terminal 20 is not located in the communication areas E4 to E6 of the base stations S4 to S6, so the call reception request by the second paging signal fails.

[0018] If the call reception request by the second paging signal fails, the MME 30 causes all base stations S in the tracking area list L that includes the tracking area TA2 (the tracking area TA that transmitted the second paging signal) to transmit paging signals (see FIG. 4 ). Hereinafter, transmitting paging signals from all base stations S in the tracking area list L that includes the tracking area TA that transmitted the second paging signal is referred to as "third paging," and the paging signal transmitted in the third paging is referred to as the "third paging signal." The term "third paging" may also be referred to as "re-resend paging." The term "third paging signal" may also be referred to as "re-resend paging signal." In the example shown in FIG. 4 , the tracking area TA2 is included in the tracking area list L1. Therefore, the third paging signal is transmitted to the communication areas E1 to E9 of the base stations S1 to S9 that belong to the tracking area list L1. In the example shown in FIG. 4 , since the communication terminal 20 is located in the communication area E1 of the base station S1, the call reception request is successful by the third paging signal.

[0019] In addition, if the incoming call request fails even with the third paging signal, MME 30 causes paging signals to be transmitted not only from base stations S in the tracking area list L1 but also from base stations S belonging to other tracking area lists L adjacent to tracking area list L1 (for example, tracking area list L2 shown in Figure 5).

[0020] In this way, if the call reception request at communication terminal 20 fails, the transmission range of the paging signal expands, and the processing load at each base station S increases. For example, considering the number of paging signal transmissions at base stations S1 to S9, if the call reception is successful at the first paging, the total number of paging signal transmissions is 1 (first paging signal from base station S5). If the call reception is successful at the second paging, the total number of paging signal transmissions is 4 (first paging signal from base station S5 + second paging signals from base stations S4 to S6). If the call reception is successful at the third paging, the total number of paging signal transmissions is 13 (first paging signal from base station S5 + second paging signals from base stations S4 to S6 + third paging signal from base stations S1 to S9).

[0021] Furthermore, the greater the number of communication terminals 20 in the communication system 1, the greater the number of paging signals transmitted, resulting in a larger processing load at each base station S. If the processing load exceeds the processing capacity of the base station S, communication failure may occur, and it is therefore desirable to reduce the number of paging signals transmitted throughout the communication system 1. One example of a measure to reduce the number of paging signals transmitted is to set a tracking area TA so that, even when the communication terminal 20 moves, it is more likely to be located in the same tracking area TA before and after the movement.

[0022] Another signal generated in the communication system 1 is a location registration signal RS. The location registration signal RS is transmitted to the MME 30 when the communication terminal 20 moves between communication areas E of base stations S that belong to different tracking area lists L.

[0023] Fig. 5 is a schematic diagram showing a location registration signal RS. In addition to the base stations S1 to S9 belonging to the tracking area list L1 shown in Fig. 2 etc., Fig. 5 also shows base stations S10 to S14 belonging to the tracking area list L2 (denoted as "TA-List2" in the figure). The tracking area list L2 includes tracking areas TA4 to TA5. The tracking area TA4 contains base stations S10 to S12. In other words, the base stations S10 to S12 belong to the tracking area TA4. Furthermore, the tracking area TA5 contains base stations S13 to S14.

[0024] 5 , when communication terminal 20 moves from communication area E9 of base station S9 belonging to tracking area list L1 to communication area E10 of base station S10 belonging to tracking area list L2, communication terminal 20 transmits a location registration signal RS to MME 30. The location registration signal RS is transmitted to MME 30 via base station S. Therefore, an increase in the number of location registration signals RS transmitted is one factor that increases the processing load of base station S.

[0025] One possible measure for transmitting the location registration signal RS is to increase the number of base stations S belonging to one tracking area list L. On the other hand, since the third paging signal is transmitted to all base stations S belonging to one tracking area list L, it is predicted that the greater the number of base stations S belonging to one tracking area list L, the greater the number of transmitted paging signals. In other words, there is a trade-off between the number of transmitted location registration signals RS and the number of transmitted paging signals.

[0026] A-2. Communication Management Device Fig. 6 is a block diagram showing the configuration of the communication management device 10. The communication management device 10 is, for example, an information processing terminal owned by a business operator (telecommunications carrier) that manages and operates the communication system 1. More specifically, the communication management device 10 is, for example, a quantum computer, or a computer that is connected to a quantum computer and can cause the quantum computer to execute specific processing.

[0027] The communication management device 10 includes a display device 101, an input device 102, a communication device 103, a storage device 104, a processing device 105, and a bus 120 that interconnects these devices.

[0028] The display device 101 is a display device (for example, various display panels such as a liquid crystal display panel or an organic EL display panel) that displays information to the outside. The input device 102 is an input device (for example, a keyboard, a mouse, a microphone, a switch, a button, or a sensor) that accepts input from the outside. The display device 101 and the input device 102 may be integrated into one device (for example, a touch panel). The communication device 103 has an interface that can be connected to a network, and communicates with other devices connected to the network using wireless or wired communication.

[0029] The storage device 104 is a recording medium readable by the processing device 105. The storage device 104 includes, for example, a nonvolatile memory and a volatile memory. The nonvolatile memory is, for example, a read-only memory (ROM), an erasable programmable read-only memory (EPROM), and an electrically erasable programmable read-only memory (EEPROM). The volatile memory is, for example, a random access memory (RAM). The storage device 104 stores a program PG1. The program PG1 is a program for operating the communication management device 10.

[0030] The processing device 105 includes one or more central processing units (CPUs). The one or more CPUs are examples of one or more processors. Each of the processors and CPUs is an example of a computer. The processing device 105 reads a program PG1 from the storage device 104. By executing the program PG1, the processing device 105 functions as a management unit 111, a first determination unit 112, a second determination unit 113, and a first correction unit 114.

[0031] The management unit 111, the first determination unit 112, the second determination unit 113, and the first correction unit 114 may be configured by circuits such as a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), and an FPGA (Field Programmable Gate Array).

[0032] The management unit 111 manages a plurality of tracking areas TA including the communication area E of at least one base station S among the plurality of base stations S, and a plurality of tracking area lists L each including at least one tracking area TA among the plurality of tracking areas TA.

[0033] Taking base station S shown in FIGS. 2 to 5 as an example, communication system 1 has at least two tracking area lists L1 and L2. Tracking area list L1 includes tracking areas TA1 to TA3. Tracking area TA1 includes communication areas E1 to E3 of base stations S1 to S3. Tracking area TA2 includes communication areas E4 to E6 of base stations S4 to S6. Tracking area TA3 includes communication areas E7 to E9 of base stations S7 to S9. Furthermore, tracking area list L2 includes tracking areas TA4 to TA5. Tracking area TA4 includes communication areas E10 to E12 of base stations S10 to S12. Tracking area TA5 includes communication areas E13 to E14 of base stations S13 to S14.

[0034] The management unit 111 manages these tracking area lists L1 to L2 and tracking areas TA1 to T5. "Manage" refers to notifying each base station S of the tracking area TA and tracking area list L determined by, for example, a first determination unit 112, a second determination unit 113, and a first correction unit 114, which will be described later.

[0035] The first determination unit 112 determines to which of the multiple tracking area lists L each of the multiple base stations S belongs. In the present embodiment, the first determination unit 112 determines the tracking area list L to which each of the multiple base stations S belongs by obtaining a first solution that satisfies at least one of minimizing the number of paging signal transmissions in each of the multiple tracking area lists L and minimizing the number of location registration signals RS transmitted when the communication terminal 20 moves between tracking areas TA belonging to different tracking area lists L. In the present embodiment, the first determination unit 112 determines the tracking area list L to which each of the multiple base stations S belongs by obtaining, as the first solution, a solution that satisfies minimizing the number of paging signal transmissions and minimizing the number of location registration signals in each of the multiple tracking area lists L. Furthermore, the first determination unit 112 may determine the tracking area list L to which each of the multiple base stations S belongs by obtaining, as the first solution, a solution that further satisfies equalizing the number of initial paging signal transmissions in each of the multiple tracking area lists L.

[0036] Hereinafter, "minimizing the number of paging signal transmissions in each of the multiple tracking area lists L" may be expressed as "minimizing all paging signals." "Minimizing the number of location registration signal RS transmissions" may be expressed as "minimizing location registration signal RS." "Uniformizing the number of initial paging signal transmissions in each of the multiple tracking area lists L" may be expressed as "uniformizing first paging signals."

[0037] The second determination unit 113 determines to which of at least one tracking area TA included in one tracking area list L a base station belonging to one of the multiple tracking area lists L belongs. The second determination unit 113 determines the tracking area TA to which the base station S belonging to the one tracking area list L belongs by finding a second solution that minimizes the number of paging signal transmissions in the one tracking area list L.

[0038] The first determination unit 112 and the second determination unit 113 obtain the first and second solutions using, for example, quantum annealing. Quantum annealing is known to quickly obtain good solutions to combinatorial optimization problems. Quantum annealing is performed in the following steps: [1] converting the objective function to a QUBO (Quadratic Unconstrained Binary Optimization) format; [2] mapping to a circuit; and [3] performing quantum annealing. If the communication management device 10 is a quantum computer, the first determination unit 112 and the second determination unit 113 may perform the above steps [1] to [3]. Furthermore, if the communication management device 10 is a computer connected to a quantum computer, the first determination unit 112 and the second determination unit 113 may request the quantum computer to perform step [3] to obtain the first and second solutions.

[0039] In the mapping to the circuit in step [2], if there is a problem in which multiple variables are all interrelated, it is necessary to generate a topology in which the quantum bit into which each variable is embedded is connected to all other quantum bits. However, due to the current limitations of machine configuration, one variable is configured with multiple quantum bits to realize the topology. In the optimization problem of base stations S handled in this embodiment, for example, the number of base stations S is 300, the number of tracking areas TA is 10, the number of tracking area lists L is 3, etc., and the problem scale is large. Therefore, there is a shortage of quantum bits, and mapping cannot be done at once.

[0040] Therefore, in this embodiment, the processing is divided into two stages, with the first determination unit 112 determining which tracking area list L each base station S belongs to, and the second determination unit 113 determining which tracking area TA each base station S belongs to. This makes it possible to divide the problem into a scale that can be solved by a quantum computer.

[0041] The following describes in detail the processing by the first determination unit 112 and the second determination unit 113. The processing by the first determination unit 112 may be referred to as "optimization of the tracking area list L" or simply as "optimization." Furthermore, the processing by the second determination unit 113 may be referred to as "optimization of the tracking area TA" or simply as "optimization."

[0042] The following explanation is based on the following assumptions: [1] Generally, communication of one base station S is configured using multiple sectors, but sectors are not taken into consideration in this optimization (sectors within one base station S are assumed to belong to the same tracking area TA). [2] Only the first re-transmission of a paging signal (third paging) is taken into consideration, and the third re-transmission (fourth paging) and beyond are not taken into consideration. [3] A paging method for data communication is used. [4] Movement of communication terminal 20 is counted in units of communication area E of base station S.

[0043] Of the base stations S in the communication system 1, the number of base stations S to be optimized this time is assumed to be e (e is an integer equal to or greater than 1). One or more tracking area lists L to be optimized are assumed to be A = {a, b, ...}. a, b, etc. indicate individual tracking area lists L. The tracking area list L indicated by a is referred to as the "ath tracking area list L". The tracking area list L indicated by b is referred to as the "bth tracking area list L". The number of tracking area lists L to be optimized is indicated as |A|. The number of tracking areas in each tracking area list L is indicated as |a|, |b|, ... The number of tracking areas TA in the tracking area list L to be optimized is f ｓｕｍ This is shown as (=|a|+|b|+...).

[0044] Next, the data for the simulation will be described. In this embodiment, a mobility model M of the communication terminal 20 is used for the simulation of the paging signal. Ｐ The moving model M Ｐ is generated using statistical values ​​indicating the hourly movement status of the communication terminal 20. Ｐ is a matrix with e rows and e columns as shown in the following formula (1). Ｐ can be rephrased as a movement matrix. Ｐ The elements (components) of m ｐ ｋ，ｉ k and i are integers from 1 to e. ｐ ｋ，ｉis the total number of communication terminals 20 that were located in the communication area E of the kth base station S when the Nth (N is an integer greater than or equal to 1) incoming call ended and moved to the i-th base station S when the N+1th incoming call was received.

[0045]

[0046] In this embodiment, a movement model M of the communication terminal 20 is used for simulating the location registration signal RS. Ｌ The moving model M Ｌ is generated using statistical values ​​indicating the hourly movement status of the communication terminal 20. Ｌ is a matrix with e rows and e columns as shown in the following formula (2). Ｌ can be rephrased as a movement matrix. Ｌ The elements (components) of m Ｌ ｋ，ｉ k and i are integers from 1 to e. Ｌ ｋ，ｉ is the total number of communication terminals 20 that have moved from the communication area E of the kth base station S to the i-th base station S.

[0047]

[0048] The tracking area list L and the tracking area TA of each of the e base stations S are represented by a matrix X shown in the following formula (3). The matrix X has e rows and f ｓｕｍ In the following formula (3), for the sake of simplicity, it is assumed that the optimization targets are two tracking area lists L, the a-th tracking area list L and the b-th tracking area list L. The elements (components) of the matrix X are, for example, x ａ ｉ，ｊ It is written as x ａ ｉ，ｊ indicates a flag = {1, 0} indicating whether the i-th base station S belongs to the j-th tracking area TA of the a-th tracking area list L. Since each base station S belongs to only one tracking area list L and tracking area TA, the total value in the horizontal direction (rows) of matrix X is restricted to 1, as shown in the following formula (4).

[0049]

[0050] [Processing of first determination unit 112] [Minimization of all paging signals] The matrix X' shown in the following formula (5) is a matrix with e rows and |A| columns indicating to which tracking area list L each base station S belongs. As described above, in this embodiment, the targets of optimization are the a-th tracking area list L and the b-th tracking area list L, and therefore the following formula (5) shows the case where |A|=2. The elements of the matrix X' are, for example, x' ａ ｉ It is written as x' ａ ｉ indicates a flag={1, 0} indicating whether the i-th base station S belongs to the a-th tracking area list L. As shown in the following formula (6), x' ａ ｉ is a base station S belonging to a tracking area TA in the a-th tracking area list L.

[0051]

[0052] The total number D of first paging signals received by the base station S belonging to the a-th tracking area list L ａ is expressed by the following formula (8): ａ The parameter (p ｋ ) is expressed by the following formula (7): ｋ indicates the number of times that the position of the communication terminal 20 was within the communication area E of the k-th base station S when the previous call was ended. ｋ is the number of occurrences of the first paging signal targeted at the kth base station S.

[0053]

[0054] The total number D' of second paging signals received by the base station S belonging to the a-th tracking area list L ａ is expressed by the following formula (15): ａ The parameters for R are shown in the following equations (9) to (14). ２ is a matrix of e rows and e columns indicating whether the base stations S are different from each other.２ ｋ，ｉ is a flag indicating whether the kth base station S and the i-th base station S are different base stations S. More specifically, if the kth base station S and the i-th base station S are different base stations S, it takes on a value of 1, and if the kth base station S and the i-th base station S are the same base station S, it takes on a value of 0.

[0055] P' shown in formula (11) ｋ indicates the number of times that the position of the communication terminal 20 at the time of the previous call termination was within the communication area of ​​the k-th base station S, and the position of the communication terminal 20 at the time of the current call termination was not within the communication area of ​​the k-th base station S. In other words, P' ｋ is the number of occurrences of the second paging signal targeted at the kth base station S.

[0056] A shown in the following formula (12) ａ ｊ is the number of base stations S belonging to the j-th tracking area TA in the a-th tracking area list L. B ａ ｊ is the number of second paging signals received by each base station S belonging to the j-th tracking area TA in the a-th tracking area list L. C shown in the following equation (14) ａ ｊ is the total number of receptions of the second paging signal from the base station S belonging to the a-th tracking area list L.

[0057]

[0058]

[0059] The total number H of receptions of the third paging signal at the base station S belonging to the a-th tracking area list L ａ is expressed by the following formula (20): ａ The parameters related to are shown in the following equations (16) to (19). ａ is a matrix with e rows and e columns indicating whether the base stations S belonging to the a-th tracking area list L belong to different tracking areas TA. ａｋ，ｉ is a flag indicating whether the kth base station S and the i-th base station S in the a-th tracking area list L belong to different tracking areas TA. More specifically, if the kth base station S and the i-th base station S belong to different tracking areas TA, the flag takes on 1, and if the kth base station S and the i-th base station S belong to the same tracking area TA, the flag takes on 0.

[0060] G shown in formula (18) ａ is the total number of times the third paging signal occurs in the a-th tracking area list L. e shown in equation (19) ａ is the number of base stations S in the a-th tracking area list L.

[0061]

[0062]

[0063] From the above, the total number of paging signals received by the base station S belonging to the a-th tracking area list L is calculated as Y ａ is given by the following equation (21). The total number Y of paging signals received at all base stations S belonging to the tracking area list L to be optimized is given by the following equation (22). α in equation (22) is a weighting coefficient for the number of paging signals in each tracking area list L, and is specified during optimization calculations. The solution that minimizes Y is the solution that satisfies the "minimization of all paging signals."

[0064]

[0065] [Minimization of location registration signal RS] The total number of times the location registration signal RS is generated G Ｌ is expressed by the following formula (25): Ｌ The parameters related to are shown in the following equations (23) to (24). Ｌ is a matrix of e rows and e columns indicating whether or not the base stations S belong to different tracking area lists L. Ｌ ｋ，ｉis a flag indicating whether the kth base station S and the ith base station S belong to different tracking area lists L. More specifically, if the kth base station S and the ith base station S belong to different tracking area lists L, it takes 1, and if the kth base station S and the ith base station S belong to the same tracking area list L, it takes 0. G Ｌ The solution that minimizes is the solution that satisfies the "minimization of the location registration signal RS."

[0066]

[0067] [Uniformization of First Paging Signals] The total number D of first paging signals received by the base stations S belonging to the a-th tracking area list L is ａ is shown in the above formula (8). Similarly, the total number of receptions of the first paging signal at the base station S belonging to the b-th tracking area list L is expressed as D ｂ Let us assume that: (D ａ -D ｂ ) ２ The solution that minimizes is the solution that satisfies the "uniformity of the first paging signal".

[0068] From the above, the first determination unit 112 determines a solution that minimizes the equation f1 shown in the following equation (26) as the first solution. In equation (26), Y is a term related to minimizing all paging signals, and G Ｌ is a term related to minimizing the location registration signal RS, and (D ａ -D ｂ ) ２ is a term relating to equalization of the first paging signal. α is a weighting coefficient for the term of all paging signals. β is a weighting coefficient for the term of the location registration signal RS. γ is a weighting coefficient for the term of the first paging signal.

[0069]

[0070] [Processing of Second Determination Unit 113] The second determination unit 113 determines to which tracking area TA each base station S belongs. As described above, the second determination unit 113 determines the tracking area TA to which the base station S belonging to one tracking area list L belongs by finding the second solution that minimizes the number of transmissions of all paging signals in the one tracking area list L.

[0071] [Minimizing all paging signals] The following description will be given taking the a-th tracking area list L as an example. The matrix X'' shown in the following equation (27) is a matrix with e rows and |a| columns indicating to which tracking area TA each base station S belongs. In this embodiment, for convenience of explanation, it is assumed that the a-th tracking area list L includes two tracking areas TA, c and d (hereinafter referred to as the c-th tracking area TA and the d-th tracking area TA). Therefore, the following equation (27) shows the case where |a|=2. The elements of the matrix X'' are, for example, x'' ｃ ｉ It is written as x'' ｃ ｉ indicates a flag={1, 0} indicating whether the i-th base station S belongs to the c-th tracking area TA.

[0072]

[0073] The total number of receptions D of the first paging signal at the base station S belonging to the c-th tracking area TA ｃ is expressed by the following formula (29): ｃ The parameter (p ｋ ) is expressed by the following formula (28): ｋ indicates the number of times that the position of the communication terminal 20 was within the communication area of ​​the k-th base station S when the previous call was ended. ｋ is the number of occurrences of the first paging signal targeted at the kth base station S.

[0074]

[0075] The total number D' of second paging signals received by the base station S belonging to the c-th tracking area TAｃ is expressed by the following equation (36): In equation (36), |c| is the number of base stations belonging to the c-th tracking area TA. D' ｃ The parameters for R are shown in the following formulas (30) to (35). ２ is a matrix of e rows and e columns indicating whether the base stations S are different from each other. ２ ｋ，ｉ is a flag indicating whether the kth base station S and the i-th base station S are different base stations S. More specifically, if the kth base station S and the i-th base station S are different base stations S, it takes on a value of 1, and if the kth base station S and the i-th base station S are the same base station S, it takes on a value of 0.

[0076] P' shown in the following formula (32) ｋ indicates the number of times that the position of the communication terminal 20 at the time of the previous call termination was within the communication area of ​​the k-th base station S, and the position of the communication terminal 20 at the time of the current call termination was not within the communication area of ​​the k-th base station S. In other words, P' ｋ is the number of occurrences of the second paging signal targeted at the kth base station S.

[0077] A shown in the following formula (33) ｃ ｊ is the number of base stations S belonging to the c-th tracking area TA. ｃ ｊ is the number of second paging signals received by each base station S belonging to the c-th tracking area TA. ｃ ｊ is the total number of receptions of the second paging signal from the base station S belonging to the c-th tracking area TA.

[0078]

[0079]

[0080] The total number H of receptions of the third paging signal at the base station S belonging to the c-th tracking area TA ｃcan be expressed as the following equation (39): The total number of receptions of the third paging signal is the same for base stations S belonging to the same tracking area list L. However, if the tracking area list L includes a base station S with a high reception failure rate (described later), or if the number of base stations S in the tracking area list L is relatively large (if the size of the tracking area list L is large), the total number of receptions of the third paging signal will be relatively large compared to base stations S in other tracking area lists L.

[0081] H ｃ The parameters for M' are shown in the following equations (37) and (38). Ｐ is a mobility model of the communication terminal 20. Ｐ is generated using statistical values ​​indicating the movement status of the communication terminal 20 within the tracking area TA. Ｐ The elements (components) of m' ｐ ｋ，ｉ where k and i are integers from 1 to e. ｐ ｋ，ｉ is the total number of communication terminals 20 that were located in the communication area E of the kth base station S when the Nth incoming call was ended and moved to the i-th base station S when the N+1th incoming call was ended. e ａ is the number of base stations S in the c-th tracking area TA (a constant).

[0082]

[0083] From the above, the total number of paging signals received by the base station S belonging to the c-th tracking area TA is calculated as Y ｃ is given by the following equation (40). Then, the total number Yt of paging signals received by all base stations S belonging to the a-th tracking area list L is given by the following equation (41). δ in equation (41) is a weighting coefficient for the number of paging signals in each tracking area TA, and is specified during optimization calculation. The solution that minimizes Yt is the second solution that satisfies the "minimization of all paging signals."

[0084]

[0085] The first correction unit 114 corrects the tracking area TA to which the base station S belonging to one tracking area list L determined by the second determination unit 113 belongs, based on the position of the base station S belonging to the one tracking area list L. If the solution obtained by the above calculation is a local solution, a counterintuitive optimization result may occur. Specifically, for example, two base stations S located close to each other may belong to different tracking areas TA, or a base station S located far away from the other base stations S may exist among multiple base stations S belonging to the same tracking area TA. The first correction unit 114 corrects the optimization result using the position information of each base station S. This can further improve the accuracy of the optimization result, and further reduction in paging signals and the like can be expected. Note that "correction" may also be referred to as "re-optimization."

[0086] The first correction unit 114 first selects a base station S to be corrected. Then, the first correction unit 114 sets the belonging of the tracking area TA of the base station S selected as the correction target as a variable, and the belonging of the tracking areas TA of the other base stations S as constants, and corrects the tracking area TA to which the base station S belongs by performing the calculations of the above formulas (27) to (41).

[0087] A method for selecting a base station S to be corrected will be described below. The first correction unit 114 acquires latitude and longitude information of the base station S to be optimized. The latitude and longitude information of the base station S is an example of information indicating the position of the base station S. The first correction unit 114 groups the latitude and longitude information of the base stations S belonging to each tracking area TA to determine the center of gravity of each tracking area TA. The center of gravity of the tracking area TA may be, for example, a position where the sum of the distances from each base station S belonging to the tracking area TA is minimum. Furthermore, the first correction unit 114 calculates the distances between the center of gravity of the tracking area TA and all base stations S belonging to the tracking area TA. The first correction unit 114 selects a base station S that satisfies the following [Condition 1] or [Condition 2] as the base station S to be corrected.

[0088] [Condition 1] If the distance between two base stations S is less than d [m] and the base stations belong to different tracking areas TA, these two base stations S are subject to correction. In other words, the first correction unit 114 selects a first base station S and a second base station S from the base stations S belonging to one tracking area list L, and corrects the tracking area TA to which the first base station S and the second base station S belong if the distance between the positions of the first base station S and the second base station S is less than a predetermined distance and the first base station S and the second base station S belong to different tracking areas TA.

[0089] More specifically, the first correction unit 114 calculates the distance between any two base stations S among the base stations S to be optimized using spherical trigonometry. Base stations S whose calculated distance is equal to or less than d [m] and which belong to different tracking areas TA after optimization are extracted without overlapping and are subject to correction. This allows re-optimization to be performed on base stations S that are assigned to different tracking areas TA despite being located in geographically close locations.

[0090] [Condition 2] The base station S that ranks highest when sorted by distance from the center of gravity of the tracking area TA is the target of correction. In other words, the first correction unit 114 identifies a predetermined number of base stations S that belong to one tracking area TA in order of furthest from the center of gravity of the tracking area TA, and corrects the tracking area to which the predetermined number of base stations S belong.

[0091] More specifically, the first correction unit 114 calculates the distance between each base station S and the center of gravity of the tracking area TA to which the base station S belongs by spherical trigonometry. The first correction unit 114 targets a predetermined number of base stations that are farthest from the center of gravity as correction targets. This allows re-optimization to be performed on base stations S that are farthest from the center of gravity of the tracking area TA to which they belong.

[0092] The number of base stations S to be corrected may be determined in advance. For example, let the number of base stations S to be corrected be N. When the problem scale (number of base stations S to be optimized x total number of tracking areas TA assigned to the base stations S to be optimized (hereinafter referred to as "total number of assigned TAs")) is 5000 variables or less, for example, N = number of base stations S to be optimized x 50%. When the problem scale is more than 5000 variables, for example, N = 5000 / total number of assigned TAs.

[0093] Furthermore, the base station S that satisfies condition 2 may be selected from the base stations S that do not satisfy condition 1. In this case, first, the base station S that satisfies condition 1 is selected from the e base stations S to be optimized. Assume that there are m base stations S that satisfy condition 1. Next, of the e-m base stations S that do not satisfy condition 1, the top N-m base stations that are farthest from the center of gravity are selected as the base stations S that satisfy condition 2.

[0094] FIG. 7 is a diagram schematically showing the relationship between the position of base station S and tracking area TA. FIGS. 8A and 8B are tables showing the tracking area TA to which base station S belongs. In FIG. 7, base stations S1 to S8 are shown in a tracking area list L1 (denoted as "TA-List1" in the figure). It is assumed that the second determination unit 113 has determined that base stations S1 to S3 and S7 belong to tracking area TA-B, base stations S4 and S5 belong to tracking area TA-C, and base stations S6 and S8 belong to tracking area TA-D. The star mark in each tracking area TA indicates the center of gravity of that tracking area TA.

[0095] 8A, if the number at the intersection of a base station name and a tracking area name is "1", this indicates that the base station S belongs to the tracking area TA. For example, base station S1 belongs to tracking area TA-B.

[0096] The first correction unit 114 selects a base station S that satisfies the above conditions 1 and 2 from among the base stations S1 to S8. For example, the distance between base station S5 and base station S6 is close (distance d [m] or less), but they belong to different tracking areas TA. Therefore, base stations S5 and S6 satisfy the above condition 1 and are determined to be targets for correction. Furthermore, the distance from the center of gravity of tracking area TA-B of base station S7 is farther than the other base stations S1 to S3 that belong to the same tracking area TA-B. Therefore, base station S8 satisfies the above condition 2 and is determined to be a target for correction.

[0097] 8B, the first correction unit 114 performs the calculations of the above formulas (27) to (41) using the tracking area TA to which the base stations S5 to S7 that are the subject of correction belong as a variable (denoted as x in the figure) and the tracking areas TA to which the other base stations S1 to S4 and S8 belong as constants. This makes it possible to more accurately optimize the tracking area TA to which the base station S belongs.

[0098] 9 is a flowchart showing the operation of the processing device 105 of the communication management device 10. The processing device 105 determines various parameters (e.g., a movement model M) required for calculations in the first determination unit 112 and the second determination unit 113. Ｐ , M Ｌ etc.) are acquired (step S100).

[0099] The processing device 105 functions as a first determination unit 112 and determines the tracking area list L to which each of the multiple base stations S belongs by finding a first solution that satisfies the uniformity of the initial paging signal, the minimization of the paging signal, and the minimization of the location registration signal RS (step S102).

[0100] In addition, the processing device 105 functions as a second determination unit 113 and determines the tracking area TA to which each base station S belongs by finding a second solution that satisfies the minimization of paging signals in one tracking area list L (step S104).

[0101] The processing device 105 functions as the first correction unit 114 and corrects the tracking area TA to which each base station S belongs based on the position of each base station S (step S106). Thereafter, the processing device 105 outputs the optimization processing result indicating the tracking area TA to which each base station S belongs and the tracking area list L (step S108), and ends the processing of this flowchart.

[0102] As described above, when optimizing the tracking area TA and tracking area list L to which the base station S belongs, the communication management device 10 according to the embodiment first determines the tracking area list L to which each base station S belongs, and then determines the tracking area TA to which each base station S belongs. By dividing the processing into two stages, a solution can be obtained even when the number of base stations S is large and the problem is large in scale.

[0103] Furthermore, the communication management device 10 uses quantum annealing to determine the tracking area list L and tracking area TA to which each base station S belongs. This allows the calculation time to be dramatically reduced compared to a classical computer, and allows the device 10 to solve problems that cannot be solved by a classical computer.

[0104] Furthermore, the communication management device 10 corrects the tracking area TA to which each base station S belongs, based on the position of each base station S. Therefore, even if a counterintuitive optimization result occurs, such as when the solution obtained by the calculation is a local solution, re-optimization can be performed, and the tracking area TA to which the base station S belongs can be optimized with greater precision.

[0105] B: Modifications B1: First Modification In the above-described embodiment, the assignment of a base station S to the tracking area list L is determined so as to satisfy the requirements of minimizing all paging signals, minimizing the location registration signal RS, and uniforming the first paging signal. In addition to this, the assignment of a base station S to the tracking area list L may be determined taking into account the failure rate of incoming calls.

[0106] 10 is a block diagram showing the configuration of a communication management device 10A according to the first modification. In addition to the configuration of the communication management device 10 described above, the communication management device 10A according to the first modification includes a second correction unit 115. The second correction unit 115 corrects the tracking area list L to which each of the plurality of base stations S determined by the first determination unit 112 belongs, based on the failure rate of paging signal reception at each of the plurality of base stations S.

[0107] As described above, the paging signal is transmitted multiple times while expanding the transmission area. The third paging signal is transmitted to all base stations S in the tracking area list L, but if the destination communication terminal 20 is unable to receive radio waves, a fourth paging signal (hereinafter referred to as the "fourth paging signal") is transmitted.

[0108] The fourth paging signal is transmitted from all base stations S in the tracking area list L. Therefore, when the fourth paging signal is transmitted, the total number of paging signal transmissions in one tracking area list L is approximately twice the total number of paging signal transmissions up to the third paging signal. For example, assume that there are 30 base stations S in the tracking area TA to which a certain base station S belongs, and that there are 300 base stations S in the tracking area list L. In this case, the total number of transmissions up to the third paging signal is 331 (the first paging signal 1 + the second paging signal 30 + the third paging signal 300), whereas the total number of transmissions after the transmission of the fourth paging signal becomes 631 (the above 331 + the fourth paging signal 300). A total of 631 paging signals are transmitted to check the coverage status of one communication terminal 20. As such, the majority of paging signals transmitted from base stations S are due to failed incoming call requests. Therefore, it is desirable to optimize the tracking area list L taking into account failed incoming call requests.

[0109] In the first modification, it is defined that the "incoming call is successful" when the destination terminal responds to any of the first to third paging signals (when paging is completed), and that the "incoming call is unsuccessful" when a fourth paging signal is transmitted (when paging is not completed). The second correction unit 115 calculates the belonging state of the plurality of base stations S to the tracking area list L determined by the first determination unit 112 and the mobility model M Ｐ and simulate paging signals generated in each tracking area list L. Then, the second correction unit 115 calculates the failure rate of each base station S using the following equation (42). In the following equation (42), the number of successful outgoing calls is the number of paging signals originating from successful incoming requests among the paging signals transmitted from one base station S. Also, the number of failure outgoing calls is the total number of paging signals transmitted from one base station S minus the number of successful outgoing calls.

[0110] Failure rate = (number of failed calls) / (number of successful calls + number of failed calls) (42)

[0111] Examples of reasons why the destination communication terminal 20 cannot receive radio waves include the communication terminal 20 being powered off, the communication terminal 20 being in an out-of-service area, or the communication terminal 20 being located around a building that makes it difficult for radio waves to connect. Of these reasons, the out-of-service area and the building that makes it difficult for radio waves to connect are fixed conditions, so the failure rate varies for each base station S. Therefore, the second correction unit 115 calculates the failure rate for each base station S and adjusts the assignment to the tracking area list L so that base stations S with high failure rates are not concentrated in some tracking area lists L.

[0112] As an example, the second correction unit 115 may divide or reorganize N tracking area lists L (N is an integer equal to or greater than 1) including a tracking area list L to which a base station S with a high failure rate belongs, into N+1 or more tracking area lists L. This reduces the total number of paging signals transmitted in one tracking area list L. In this case, it is preferable to prevent the number of belonging base stations S from varying too much among the N+1 or more tracking area lists L (or all tracking area lists L managed by the telecommunications carrier) after the division or reorganization. In other words, it is preferable to perform the division or reorganization so that the number of belonging base stations S in one tracking area list L is within a predetermined range.

[0113] As another example, the second correction unit 115 may assign base stations S with high failure rates to different tracking area lists L so that the average failure rate of the base stations S belonging to each tracking area list L is within a certain range.

[0114] According to the first modification, the failure rate of incoming calls is taken into consideration when determining whether a base station S should belong to the tracking area list L. This distributes the processing load resulting from failed incoming call requests, which account for a large portion of paging signals, and improves the processing efficiency of the communication system 1.

[0115] In addition, the second correction unit 115 may correct the tracking area TA to which each of the multiple base stations S determined by the second determination unit 113 belongs, based on the failure rate of paging signal reception at each of the multiple base stations S.

[0116] B2: Second Modification Based on the failure rate described in the first modification, for example, the tracking area TA to which each base station S belongs in the currently operated tracking area list L may be optimized. That is, the communication management device 10 may include a management unit 111 that manages multiple tracking areas TA including the communication area of ​​at least one base station among the multiple base stations S and multiple tracking area lists L, each including at least one tracking area TA among the multiple tracking areas TA, and a third determination unit (not shown) that determines to which of at least one tracking area TA included in the tracking area list L a base station S belonging to one of the multiple tracking area lists L belongs. In this case, the third determination unit determines the tracking area TA to which a base station S belonging to one tracking area list L belongs, based on a mobility model MP that indicates the movement status of the communication terminal 20 within one tracking area list L and the failure rate of paging signal reception at each of the multiple base stations S.

[0117] Specifically, the third determination unit determines, for example, the belonging state of each base station S currently in operation to the tracking area list L and the mobility model M Ｐ and simulates a paging signal generated in each tracking area list L. The third determination unit calculates the failure rate of each base station S using the above formula (42). The third determination unit determines the membership of each base station S to a tracking area TA so that there is no large variation in the failure rates of the base stations S belonging to each tracking area TA.

[0118] According to the second modification, the tracking area TA of a base station S is determined taking into consideration the failure rate of incoming calls. This distributes the processing load resulting from failed incoming call requests, which account for a large portion of paging signals, and improves the processing efficiency of the communication system 1.

[0119] B3: Third Modification In the above-described embodiment, the tracking area list L and the tracking area TA to which each base station S belongs are optimized regardless of the current state of each base station S belonging to the tracking area list L and the tracking area TA (hereinafter referred to as the "current belonging state"). On the other hand, optimization may be performed based on the current belonging state.

[0120] Specifically, the first determination unit 112 determines whether the current belonging state and the movement model M Ｐ and M Ｌ Then, the first determination unit 112 calculates the number of paging signal transmissions and the number of location registration signal transmissions based on the above. Then, the first determination unit 112 calculates a first solution under the constraint that one of the number of paging signal transmissions and the number of location registration signal transmissions is minimized, and the other of the number of paging signal transmissions and the number of location registration signal transmissions is kept at the same level as the current belonging state.

[0121] First, consider the case where a constraint is set to minimize the number of location registration signal transmissions and to keep the number of paging signal transmissions at the same level as the current belonging state. When only the number of location registration signal transmissions is minimized, the coefficients α and γ in the above equation (26) are set to 0. Furthermore, as for the constraint, for example, a solution is searched for in which the number of paging signal transmissions after optimization is less than the number of paging signal transmissions in the current belonging state. The number of paging signal transmissions in the current belonging state is determined by the current belonging state and the mobility model M Ｐ In addition, the number of paging signal transmissions after optimization is calculated by substituting the following equation (21): Ｐ and are substituted into the above equation (21).

[0122] Next, consider the case where a constraint is set to minimize the number of paging signal transmissions and to keep the number of location registration signal transmissions at the same level as the current belonging state. When only the number of paging signal transmissions is minimized, the coefficients β and γ in the above equation (26) are set to 0. Furthermore, as for the constraint, for example, a solution is searched for in which the number of location registration signal transmissions after optimization is less than the number of location registration signal transmissions in the current belonging state. The number of location registration signal transmissions in the current belonging state is determined by the current belonging state and the mobility model M Ｌ In addition, the number of transmissions of location registration signals after optimization is calculated by substituting the following equation (25): Ｌ and are substituted into the above equation (25).

[0123] That is, in the third modification, the first determination unit 112 determines a provisional state of belonging to each of the plurality of base stations S in the tracking area TA and the tracking area list L, and calculates the number of transmissions of paging signals and the number of transmissions of location registration signals in each of the plurality of tracking area lists L in the provisional belonging state based on a movement model M indicating the movement status of the communication terminal 20. Ｐ and M Ｌ The first determination unit 112 determines, as a first solution, the tracking area list L to which each of the plurality of base stations S belongs by finding a solution in which one of the number of paging signal transmissions or the number of location registration signal transmissions in each of the plurality of tracking area lists L is minimized and the other of the number of paging signal transmissions or the number of location registration signals is at the same level as the number of transmissions in the provisional belonging state. The provisional belonging state is, for example, the current belonging state.

[0124] According to the third modification, it is possible to optimize the affiliation of each base station S to the tracking area TA and the tracking area list L based on the current affiliation state. This reduces the processing load on the communication management device 10 and improves the processing efficiency in the communication system 1 without making large-scale changes to affiliation.

[0125] C: Others (1) In the above-described embodiment, ROM, RAM, etc. are given as examples of storage device 104, but storage device 104 may also be a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray (registered trademark) disk), a smart card, a flash memory device (e.g., a card, a stick, a key drive), a CD-ROM (Compact Disc-ROM), a register, a removable disk, a hard disk, a floppy (registered trademark) disk, a magnetic strip, a database, a server, or other suitable storage medium.

[0126] (2) In the above-described embodiments, the described information, signals, etc. may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0127] (3) In the above-described embodiment, input and output information may be stored in a specific location (for example, a memory) or may be managed using a management table. Input and output information may be overwritten, updated, or added to. Output information may be deleted. Input information may be transmitted to another device.

[0128] (4) In the above-described embodiment, the determination may be made based on a value represented by one bit (0 or 1), a Boolean value (true or false), or a comparison of numerical values ​​(e.g., a comparison with a predetermined value).

[0129] (5) The order of the process procedures, sequences, flowcharts, etc. illustrated in the above-described embodiments may be rearranged unless it is consistent. For example, the methods described in this disclosure present elements of various steps using an example order, and are not limited to the particular order presented.

[0130] (6) Each function illustrated in FIG. 6 is realized by any combination of hardware and / or software. Furthermore, the method for realizing each functional block is not particularly limited. That is, each functional block may be realized using a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are directly or indirectly connected (e.g., wired, wireless, etc.) and these multiple devices. A functional block may be realized by combining software with the single device or multiple devices.

[0131] (7) The programs exemplified in the above-described embodiments should be broadly construed to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., regardless of whether they are called software, firmware, middleware, microcode, hardware description language, or by other names.

[0132] Software, instructions, information, etc. may also be transmitted or received over a transmission medium. For example, if software is transmitted from a website, server, or other remote source using wired technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and / or wireless technologies (such as infrared, microwave), then these wired and / or wireless technologies are included within the definition of transmission media.

[0133] (8) In each of the foregoing embodiments, the terms "system" and "network" are used interchangeably.

[0134] (9) The information, parameters, etc. described in this disclosure may be expressed using absolute values, relative values ​​from a predetermined value, or corresponding other information.

[0135] (10) In the above-described embodiments, the portable device may be a mobile station (MS). Those skilled in the art may also refer to a mobile station as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other appropriate terminology. In this disclosure, the terms "mobile station," "user terminal," "user equipment (UE)," "terminal," etc. may be used interchangeably.

[0136] (11) In the above-described embodiments, the terms "connected," "coupled," or any variation thereof refers to any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are "connected" or "coupled" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access." As used in this disclosure, two elements may be considered to be "connected" or "coupled" to each other using at least one of one or more wires, cables, and printed electrical connections, as well as electromagnetic energy having wavelengths in the radio frequency range, microwave range, and optical (both visible and invisible) range, as some non-limiting and non-exhaustive examples.

[0137] (12) In the above embodiments, the phrase "based on" does not mean "based only on," unless otherwise specified. In other words, the phrase "based on" means both "based only on" and "based at least on."

[0138] (13) As used in this disclosure, the terms "determining" and "determining" may encompass a wide variety of actions. "Determining" and "determining" may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, inquiring (e.g., searching in a table, database, or other data structure), ascertaining something as "determining" or "determining," and the like. Furthermore, "judgment" and "decision" may include regarding receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, and accessing (e.g., accessing data in memory) as having been "judgment" or "decision." Furthermore, "judgment" and "decision" may include regarding resolving, selecting, choosing, establishing, comparing, etc. as having been "judgment" or "decision." In other words, "judgment" and "decision" may include regarding some action as having been "judgment" or "decision." Furthermore, "judgment (decision)" may be interpreted as "assuming," "expecting," "considering," etc.

[0139] (14) In the above embodiments, when "include," "including," and variations thereof are used, these terms are intended to be inclusive, similar to the term "comprising." Furthermore, the term "or," as used in this disclosure, is not intended to be an exclusive or.

[0140] (15) In this disclosure, when articles are added by translation, such as a, an, and the in English, the disclosure may include the noun following these articles being plural.

[0141] (16) In this disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "combined" may also be interpreted in the same way as "different."

[0142] (17) The aspects / embodiments described in this disclosure may be used alone, in combination, or switched depending on the implementation. Notification of predetermined information (e.g., notification that "X is true") is not limited to being explicit, but may be implicit (e.g., not notifying the predetermined information).

[0143] 1...communication system, 10, 10A...communication management device, 20...communication terminal, 101...display device, 102...input device, 103...communication device, 104...storage device, 105...processing device, 111...management unit, 112...first determination unit, 113...second determination unit, 114...first correction unit, 115...second correction unit, E (E1 to E14)...communication area, L (L1, L2)...tracking area list, PG1...program, S (S1 to S14)...base station, TA (TA1 to TA5)...tracking area.

Claims

1. A management unit that manages a plurality of tracking areas including the communication area of at least one base station among a plurality of base stations, and a plurality of tracking area lists each including at least one tracking area among the plurality of tracking areas; a first determination unit that determines, for each of the plurality of base stations, to which of the plurality of tracking area lists it belongs; and a second determination unit that determines, for a base station belonging to one of the plurality of tracking area lists, to which of the at least one tracking area included in the one tracking area list it belongs. The first determination unit determines the tracking area list to which each of the plurality of base stations belongs by obtaining a first solution that satisfies at least one of minimizing the number of paging signals transmitted in each of the plurality of tracking area lists and minimizing the number of location registration signals transmitted when a communication terminal moves between base stations belonging to different tracking area lists. The second determination unit determines the tracking area to which the base station belonging to the one tracking area list belongs by obtaining a second solution that satisfies minimizing the number of paging signals transmitted in the one tracking area list. A communication management device.

2. The communication management device according to claim 1, wherein the first determination unit determines the tracking area list to which each of the plurality of base stations belongs by obtaining, as the first solution, a solution that satisfies both minimizing the number of paging signals transmitted in each of the plurality of tracking area lists and minimizing the number of location registration signals transmitted.

3. The communication management device according to claim 2, wherein the first determination unit determines the tracking area list to which each of the plurality of base stations belongs by obtaining, as the first solution, a solution that further satisfies equalizing the number of initial paging signals transmitted in each of the plurality of tracking area lists.

4. The first determination unit determines the tracking area of each of the plurality of base stations and the provisional belonging state to the tracking area list, and calculates, based on a movement model indicating the movement state of the communication terminal, the number of paging signals transmitted in each of the plurality of tracking area lists and the number of location registration signals transmitted in the provisional belonging. As the first solution, a solution is obtained in which one of the number of paging signals transmitted in each of the plurality of tracking area lists or the number of location registration signals transmitted is minimized, and the other of the number of paging signals transmitted in each of the plurality of tracking area lists or the number of location registration signals transmitted is at the same level as the number of transmissions in the provisional belonging, thereby determining the tracking area list to which each of the plurality of base stations belongs. The communication management device according to claim 1.

5. The communication management device according to claim 1, further comprising a first correction unit that corrects the tracking area to which the base station belonging to the one tracking area list determined by the second determination unit belongs, based on the position of the base station belonging to the one tracking area list.

6. The first correction unit selects a first base station and a second base station from the base stations belonging to the one tracking area list, and corrects the tracking areas to which the first base station and the second base station belong when the distance between the position of the first base station and the position of the second base station is less than a predetermined distance and the first base station and the second base station belong to different tracking areas. The communication management device according to claim 5.

7. The first correction unit identifies a predetermined number of base stations in descending order of distance from the centroid position of the one tracking area for the base stations belonging to the one tracking area, and corrects the tracking areas to which the predetermined number of base stations belong. The communication management device according to claim 5.

8. The communication management device according to claim 1, further comprising a second correction unit that corrects the tracking area list to which each of the plurality of base stations determined by the first determination unit belongs, based on the incoming call failure rate of the paging signal in each of the plurality of base stations.

9. A communication management apparatus comprising: a management unit that manages a plurality of tracking areas including a communication area of at least one base station among a plurality of base stations, and a plurality of tracking area lists each including at least one tracking area among the plurality of tracking areas; and a third determination unit that determines to which of the at least one tracking area included in the one tracking area list the base station belonging to the one tracking area list belongs, wherein the third determination unit determines the tracking area to which the base station belonging to the one tracking area list belongs based on a movement model indicating a movement status of a communication terminal within the one tracking area list and a paging signal incoming failure rate at each of the plurality of base stations.

10. A communication management method for determining a tracking area list to which each of a plurality of base stations belongs by obtaining a first solution that satisfies at least one of minimization of the number of paging signals transmitted in each of the plurality of tracking area lists and minimization of the number of location registration signals transmitted when a communication terminal moves between base stations belonging to different tracking area lists, and for determining a tracking area to which a base station belonging to one of the plurality of tracking area lists belongs by obtaining a second solution that satisfies minimization of the number of paging signals transmitted in the one tracking area list.

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