Wireless device

Abstract

To maintain a tracking by a core network in the case where a grouping method is used for managing a mobile body.SOLUTION: A wireless device of an embodiment comprises: a group management part that generates a transmission signal containing locus information and transmits it, receives a response signal replied from the other wireless device, generates a group list including an ID of the other wireless device, and transmits a registration request of position information of itself and the other wireless devices to a core network on the basis of the group list; and a group determination part that receives the signal including the locus information of the movement of the other wireless device from the other wireless device, generates correlation information indicating a correlation of both of them on the basis of the locus information of the movement of the itself and the locus information of the movement of the other wireless device, determines whether or not it is belonged to a group formed by the other wireless device on the basis of the correlation information, and transmits the response signal containing the ID of the itself in the case where it is belonged to a result group obtained by being determined.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present invention relates to a wireless device. [Background technology]

[0002] Mobility management is an important function in cellular networks. It is the process by which the core network (CN) tracks the location of the user equipment (UE), and has two components: registration and paging.

[0003] Registration is the process by which a user equipment (UE) reports its location information to a core network (CN). In current 4G LTE (Long-Term Evolution) and EPC (Evolved Packet Core) systems, cells (i.e., Evolved Node Bs (eNBs)) are grouped to form tracking areas (TAs) that manage the movement of mobile objects. Each cell is assigned to one tracking area (TA), and each user equipment (UE) registers with one tracking area (TA). When a user equipment (UE) moves from one tracking area (TA) to another, the user equipment (UE) reports (registers) its latest location information to the core network (CN).

[0004] The procedure of registering location information to the core network CN is called Tracking Area Update in LTE / EPC. The user equipment UE needs to perform the registration or tracking area update procedure when it moves to a new tracking area TA, when the tracking area update timer expires, etc. The tracking areas TA are further grouped to form a Tracking Area List. Since the Tracking Area List contains multiple tracking areas TA, the user equipment UE can freely move between these tracking areas TA without performing the Tracking Area Update procedure. When the user equipment UE moves to another tracking area TA that is not included in the current Tracking Area List, the user equipment UE needs to complete the Tracking Area Update procedure.

[0005] Paging (Call termination) is a procedure for routing incoming data or calls to a user equipment (UE). When the core network CN (including the Mobility Management Entity (MME)) receives a call or data for the user equipment (UE), the core network CN sends a paging message in all cells that belong to the tracking area (TA) where the user equipment (UE) was recently registered. When the user equipment (UE) receives the paging message, a connection is established through the cell where the user equipment (UE) responds to the paging message. The purpose of mobility management is for the core network CN to accurately track the user equipment (UE). For this purpose, the user equipment (UE) periodically reports its location information.

[0006] The core network CN updates the reported information from time to time. If the location information in the core network CN is inaccurate, the core network CN cannot correctly forward the call to the user equipment UE.

[0007] Considering the case where the user equipment UE is not a so-called mobile phone but an equipment (M2M device) that performs M2M communication (Machine to Machine), the M2M network generally refers to a large number of M2M devices in a cellular network, and refers to hundreds of M2M devices. Therefore, in the M2M network, millions of devices will be connected to the mobile communication system in addition to the current mobile subscribers. Mobility management for a large number of devices will be a significant burden for the mobile network.

[0008] One solution to reduce mobility management related communications, especially registration related communications, is the grouping approach. In the grouping approach, M2M devices (or user equipments UE) with similar mobility patterns are grouped together and one of the devices is selected as a group leader (GL). When the group moves to a new tracking area TA, only the group leader GL performs the registration operation on behalf of the group. In this way, this approach can reduce the concentration of communications due to registration and location updates.

[0009] However, this method has a problem of being overly dependent on the group leader GL for registration and paging functions. If the group leader GL leaves the group or cannot establish a registration procedure (or a tracking area update procedure) due to interference, terminal power shortage, etc., the core network CN fails to track the entire group. In addition, the grouping method does not have a mechanism for detecting the departure of a user equipment UE or device, so if a member user equipment UE or M2M device deviates from the group's trajectory, the core network CN cannot detect the departure. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent Publication No. 2018-093537 Summary of the Invention [Problem to be solved by the invention]

[0011] In this way, in the conventional wireless device, even if the grouping method is used, there is a possibility that the core network will fail to track it. The present embodiment has been made to solve this problem, and aims to provide a wireless device that allows the core network to maintain tracking even if the grouping method is used to manage moving objects. [Means for solving the problem]

[0012] A wireless device according to an embodiment is a wireless device that connects to a base station in a core network that manages the positions of the connection partners of the base station in units of tracking areas including the communication areas of the base stations. The wireless device includes a first wireless interface that communicates with the core network via the base station, a second wireless interface that communicates with other wireless devices located in a common tracking area, a positioning unit that generates trajectory information of the wireless device's own movement based on its own past position information, and a group management unit that generates a transmission signal including the trajectory information at a predetermined timing and transmits it via the second wireless interface, receives a response signal returned from the other wireless devices in response to the transmission signal via the second wireless interface, generates a group list including IDs of the other wireless devices that returned the response signals, and transmits a registration request for position information of the wireless device itself and the other wireless devices that returned the response signals to the core network via the first wireless interface based on the group list. The wireless device also includes a group determination unit that receives a signal including movement trajectory information of another wireless device from the other wireless device via the second wireless interface, generates correlation information indicating a correlation between its own movement trajectory information and the movement trajectory information of the other wireless device based on the movement trajectory information of the other wireless device, determines whether or not the wireless device belongs to a group formed by the other wireless device based on the correlation information, and transmits a response signal including its own ID via the second wireless interface if the determination results in the wireless device belonging to the group. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing an overview of a cellular network. [Diagram 2] FIG. 2 illustrates receiving a call in a cellular network. [Diagram 3] FIG. 1 illustrates an M2M device moving in a cellular network. [Figure 4] FIG. 13 is a diagram showing a state in which a device has left a group of M2M devices. [Diagram 5] FIG. 11 is a diagram showing how a device leaves a group of M2M devices. [Figure 6] FIG. 13 is a diagram showing how grouped devices move. [Figure 7] FIG. 1 is a diagram illustrating a configuration of a device according to an embodiment. [Figure 8] FIG. 11 is a diagram illustrating a device grouping operation according to an embodiment. [Figure 9] FIG. 11 is a diagram illustrating a device grouping operation according to an embodiment. [Figure 10] FIG. 11 is a diagram showing a communication procedure in a device grouping operation. [Figure 11] FIG. 1 is a diagram showing two devices moving. [Figure 12] 11A and 11B are diagrams illustrating effects of the device according to the embodiment. [Figure 13] 11A and 11B are diagrams illustrating effects of the device according to the embodiment. [Figure 14] 11A and 11B are diagrams illustrating effects of the device according to the embodiment. [Figure 15] 11A and 11B are diagrams illustrating effects of the device according to the embodiment. [Figure 16] 11A and 11B are diagrams illustrating effects of the device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (Cellular Network Overview) A cellular network according to an embodiment will be described with reference to Fig. 1. As shown in Fig. 1, the cellular network NW according to the embodiment has a core network CN. The core network CN is a so-called backbone network, and a user equipment UE belongs to the core network CN. The core network has a system for managing location information of the user equipment UE in order to send a paging message to the user equipment UE.

[0015] The cellular network NW of the embodiment includes base stations eNB1 to eNB5. The base stations eNB1 to eNB5 are connected to a core network CN. In the example shown in FIG. 1, the communication areas (cells) of the base stations eNB1 and eNB2 each constitute a tracking area TA1. Similarly, the communication areas of the base stations eNB3 to eNB5 each constitute a tracking area TA2.

[0016] A tracking area TA is an area that is a unit for tracking a user equipment UE, which is a terminal of a cellular network. Each cell, which is a communication area of ​​each base station, is assigned to one of the tracking areas TA. The user equipment UE registers with the core network CN as being located in one of the tracking areas TA. Even if the user equipment UE moves from the cell of the base station eNB1 to the cell of the base station eNB2, the user equipment UE remains located in the tracking area TA1. On the other hand, if the user equipment UE moves from the cell of the base station eNB2 to the cell of the base station eNB3, the user equipment UE moves from the tracking area TA1 to the tracking area TA2. The core network CN manages the location and movement of the user equipment UE in units of tracking areas.

[0017] When the user equipment UE moves from a tracking area TA1 to a tracking area TA2, for example, the user equipment UE reports its latest location information to the core network CN. The location information can be expressed as the ID of the tracking area TA. In the example shown in Figure 1, the user equipment UE after moving reports the tracking area TA2 to the core network CN as its latest location information.

[0018] Next, a flow of a call received by a user equipment UE in a cellular network NW according to an embodiment (flow of incoming communication) will be described with reference to Figures 1 and 2. When the core network CN receives a call to the user equipment UE, the core network CN transmits a paging message of the user equipment UE to base stations of all cells belonging to the tracking area TA in which the user equipment UE was last registered (dash-dotted line in Figure 2). When the user equipment UE receives the paging message, a connection is established through the base station of the cell in which the user equipment UE responds to the paging message (solid line in Figure 2).

[0019] In the example shown in Figures 1 and 2, the user equipment UE after moving reports the tracking area TA2 to the core network CN as location information, so a call to the user equipment UE received by the core network CN is sent to all communication areas of base stations eNB3 to eNB5 belonging to the tracking area TA2 (dashed line in Figure 2). When the user equipment UE receives the call message, it establishes a connection through the base station eNB3 of the cell to which it belongs. Subsequent communication of the user equipment UE is performed via the base station eNB3 (solid line arrow in Figure 2).

[0020] (If the user equipment is an M2M device) With reference to FIG. 3, a case where a certain number of user equipments UE move together like M2M devices will be described. Consider a case where the user equipments UE are not so-called mobile phones but devices (M2M devices) that perform M2M communication (Machine to Machine). In this case, the number of M2M devices referenced in the cellular network NW is generally large, and hundreds of M2M devices may be referenced. Therefore, in the cellular network to which the M2M devices belong, millions of M2M devices will be connected to the cellular network in addition to the current mobile subscribers. Mobility management of a large number of devices is a significant burden for the core network CN and base stations. The example shown in FIG. 3 shows a situation in which, when multiple user equipments UE move from a tracking area TA1 to a tracking area TA2, each of the user equipments UE reports its own location information to the core network CN via the base station eNB3. In this case, the burden on the base station eNB3 and the core network CN becomes extremely large.

[0021] Therefore, in the cellular network of the embodiment, the user equipment UE first forms a group represented by a group leader GL. This group is configured with user equipment UE members that have similar movement trajectories.

[0022] (Grouping criteria) The criteria for grouping user equipments UE will be described below. Assume that there are M M2M devices m as shown in Equation 1.

number

[0023] M2M Devices x Tracking area TA i From tracking area TA j At time t, device m x The movement is expressed as in Equation 2.

number

number

number

[0024] Device m x The device m that contains the K (K>0) nearest tracking areas TA visited by x The locus of ρ x If we define (K), this can be expressed as equation 5.

number

number

number

[0025] In the cellular network of the embodiment, the user equipment UE determines whether or not grouping is appropriate based on the correlation between its own trajectory and the trajectories of other user equipment.

[0026] (User Equipment UE Grouping Procedure) Next, a grouping procedure of user equipment UE in the embodiment will be described. The grouping procedure is performed by out-of-band communication. That is, communication between M2M devices can be performed via an unlicensed communication standard (band) rather than a communication standard via a licensed base station. Any M2M device can act as a group leader GL in a group and can initiate the grouping procedure by broadcasting its movement pattern.

[0027] M2M Devicesx If device m starts the grouping procedure, x is the self-ID and the trajectory ρ x Broadcast a grouping message including (K) to other M2M devices m y When device m receives the message, y is the received trajectory ρ x (K) and the locus of self ρ y By comparing the values ​​of (K), the group leader GL device m x If the result of the calculation using Equation 6 and Equation 7 is C x,y If (K)=1, then device m y is the device m x It can be determined that there is a correlation between the movement and

[0028] Device m y is the result of the determination of device m x If there is a correlation between device m and the group, the group registration message including its own device ID is sent to device m. x This sends the y is the device m x This means that you will belong to a group with GL as the group leader.

[0029] If many devices that meet the correlation criteria for mobility send group registration messages at the same time, message collisions will occur, making it difficult to establish grouping. A pre-backoff window scheme can be applied to address this message collision problem.

[0030] The pre-backoff window method reduces collisions by having each device perform a random backoff before sending a group registration message. A device responding to a grouping message selects a random backoff in the range of 0 to Wb, where Wb is the backoff window for a predetermined time slot. A device responding to a grouping message transmits a group registration message with a time difference according to the backoff value selected by each device. This makes it possible to reduce collisions of group registration messages.

[0031] As described above, if each of the grouped user equipments reports its own location information to the core network CN, the network load will be large. Therefore, in the cellular network of the embodiment, among the grouped user equipments UE, only the group leader GL that represents the group reports the location information of its own group to the core network CN.

[0032] Device m that has become the group leader GL x The group registration message is received from multiple devices distributed in time during the time Wb, and the group formation procedure is performed. Due to the pre-backoff window scheme, many devices can receive the group registration message from device m. x The transmission to device m is successful, but x is a group registration message that contains only r group registration messages (r≦r max ) to form a group. max is a preset value that defines the maximum number of group members.

[0033] Group leader device m x The device records the group registration message and broadcasts a group acknowledgment (ACK) containing a list of the group member IDs. If a device receives the group acknowledgment and its own ID is included in the group acknowledgment, it can know that it has joined the group.

[0034] If the group receipt notification does not include the device's own ID, the device is x Therefore, the M2M device that has sent the group registration message but is not included in the list can form a group through a further grouping procedure, i.e., it can become the group leader.

[0035] (Registering and updating location information of grouped user devices) As with normal mobility management, grouped M2M devices also require a location registration procedure. That is, an M2M device registers its location information when (1) it moves to a new tracking area TA or (2) the timer expires. update When time has elapsed, the mobile station must report its location information to the core network CN.

[0036] When an M2M device belonging to a group moves to a new tracking area TA while still belonging to the group, only the group leader GL of the group can execute the registration procedure or the update procedure on behalf of the group. That is, when a group of M2M devices moves to a new tracking area TA, only the group leader GL executes the registration procedure or the tracking area update procedure. In the registration procedure or the tracking area update procedure, a tracking area update message transmitted by the device serving as the group leader GL includes a list of the IDs of the group members. Therefore, the core network CN can register and update the location information of each device belonging to the group by receiving a tracking area update message from the group leader GL. When the core network CN receives a tracking area update message from the group leader GL, it returns a tracking area update acceptance message to the device serving as the group leader GL. The device serving as the group leader GL transfers the tracking area update acceptance message to the members of the group. By receiving the tracking area update acceptance message, the device serving as the group member knows that its location information has been registered or updated in the core network CN.

[0037] The M2M device has an update timer that counts the time since it joined the group. When the count value of the update timer reaches a predetermined value T update When the update timer reaches the value T update After this time, the M2M device cancels its current group membership and performs the grouping procedure again, which allows to detect when a group member device leaves the group by periodically updating the grouping.

[0038] It is not necessary for the original group leader GL to re-execute the grouping procedure. It is also possible to re-execute it immediately after removing the GL from the group. However, since there is a possibility that the grouping procedure will be delayed if procedures to become the group leader GL are concentrated at the same time, it is desirable to have a configuration in which the grouping procedure is started with a random time difference based on the IDs of each M2M device. This makes it possible to equalize the M2M devices that become group leader GLs.

[0039] When the groups are reconstituted, the new group leader GL for each group performs a registration procedure with the core network CN.

[0040] Once the location information registration and update for each group is completed, the M2M devices belonging to the group can receive calls from the core network CN. The call procedure can be realized by sending an individual call message from the core network CN to the device, or a group call message using the group call mechanism. When the M2M device receives the call message, the device establishes a connection in response to the call message.

[0041] (Detection of departure) When a group moves to a new tracking area TA, some of the trajectories of members may leave the group. For example, as shown in Figure 4, i Tracking area TA i From tracking area TAj and move to member device m k (m k ∈G i ) is in the tracking area TA k Consider the case where we move to (k≠j).

[0042] Device m k Since device m is a member device, it does not execute the registration procedure and waits for a tracking area update acceptance message from the group leader GL. Therefore, if device m k is a given time interval T update If device m does not receive an update acceptance message from the group leader GL after the elapse of k In this case, device m k , GL, the group leader, k Execute a new grouping procedure by broadcasting (K) and the ID.

[0043] Similarly, a device that has left a group or does not belong to a group can join the group by becoming the group leader GL according to the above procedure or by responding to a group registration message from the group leader GL. After grouping, the device m that has become the new group leader GL k sends a registration message to the core network CN.

[0044] The group leader GL device m performs the new grouping procedure. k sends a modified tracking area update message to the core network CN. As a result, the core network CN notifies the device m kThe location information received from the group leader of the old group Gi and the location information received from the group leader of the current group Gk will be different. The core network CN operates to avoid confusion and false alarms by giving priority to the information in the revised registration message (the newly received information). Through the above process, the location information of the device that has left is updated in the core network CN.

[0045] The same applies when the group leader GL leaves the group. For example, as shown in FIG. i Tracking area TA i From tracking area TA j The group leader GL moves to the tracking area TA k When moving to (k≠j), the group can be updated by the same procedure.

[0046] (Configuration of the embodiment) Next, a wireless device according to an embodiment will be described with reference to Fig. 6 to Fig. 11. The wireless device according to the embodiment is an M2M device that performs so-called M2M communication, and multiple devices move along similar trajectories. As shown in Fig. 6, for example, multiple devices move by the same transportation means, and the devices perform operations such as registration with the core network CN.

[0047] Fig. 7 shows the configuration of a wireless device according to an embodiment. As shown in Fig. 7, wireless devices 1a to 1e according to an embodiment have at least a part of a common configuration, and communicate with a base station eNB and other wireless devices. In the following description, the configuration of the wireless device 1a will be described as a representative, and the common configuration of the wireless devices 1b to 1e will not be illustrated or described. As shown in Fig. 7, the wireless device 1a according to an embodiment has a wireless interface (wireless I / F) 10a, a terminal communication unit 11a, a group management unit 12a, a positioning unit 13a, a group determination unit 14a, and a storage unit 15a.

[0048] The wireless interface 10a converts data transmitted by the wireless device 1a into a transmission signal to be sent to the antenna ANT, and converts a signal received by the antenna ANT into received data. The wireless interface 10a supports a first standard for the wireless device 1a to transmit and receive voice and data through the base station eNB, and a second standard for transmitting and receiving grouping messages with other nearby wireless devices 1b to 1e.

[0049] The terminal communication unit 11a is a calculation block corresponding to a first standard. The terminal communication unit 11a generates transmission data and decodes reception data. The first standard to which the terminal communication unit 11a conforms is, for example, a standard used in a cellular network NW, and examples of the standard include the LTE and 5G standards. The terminal communication unit 11a mainly processes transmission and reception data communicated with the base station eNB.

[0050] The group management unit 12a is a calculation block that manages the group to which the wireless device 1a belongs. The group management unit 12a executes a group management procedure when the group management unit 12a becomes the group leader GL. When communicating with other wireless devices through the group management unit 12a, the wireless interface 10a can use the second standard.

[0051] The positioning unit 13a is a calculation block that acquires the position information of the wireless device 1a. The positioning unit 13a may acquire the position information by itself using a means such as a GPS, or may manage the tracking area TA to which the base station eNB with which the wireless interface 10a communicates as the position information. The positioning unit 13a calculates trajectory information on the trajectory that the wireless device 1a has moved based on its own past position information, and stores the trajectory information in the storage unit 15a.

[0052] The group determination unit 14a is a calculation block that, when receiving a grouping message transmitted by another wireless device 1b to 1e as the group leader GL, determines whether or not the wireless device belongs to the group related to the grouping message. The group determination unit 14a performs a comparison calculation between its own trajectory information generated by the positioning unit 13a and trajectory information included in the received grouping message to determine whether or not the wireless device belongs to the group. When communicating with another wireless device using the group determination unit 14a, the wireless interface 14a can use the second standard.

[0053] The storage unit 15a is a non-volatile memory that stores therein information about the group managed by the group management unit 12a, and location information and trajectory information managed by the positioning unit 13a.

[0054] Next, the operation of the wireless device of the embodiment will be described with reference to Figures 7 to 10. Here, the description will be made assuming that the wireless device 1a executes a grouping procedure and determines whether or not the wireless device 1b belongs to the group of the wireless device 1a.

[0055] The positioning unit 13a acquires information on the base station cell to which the wireless device 1a belongs and the tracking area TA via the wireless interface 10a. The positioning unit 13a associates the acquired information on the tracking area TA with time information to generate a trajectory ρ x (k) is generated and stored in the storage unit 15a (S100). x (k) constitutes trajectory information regarding the movement of the wireless device 1a.

[0056] The group management unit 12a manages whether the wireless device 1a belongs to a group. When a predetermined time has passed while the wireless device 1a does not belong to a group, or when the wireless device 1a is removed from the group to which it belonged, the group management unit 12a reads out trajectory information about its own movement stored in the storage unit 15a, and generates a transmission signal including the trajectory information and its own ID. The wireless interface 10a transmits the generated transmission signal based on the second standard (S110). As shown in FIG. 10, the transmission signal transmitted by the wireless device 1a is received by the other wireless devices 1b to 1e.

[0057] The group management unit 12a W If there is no response, the wireless interface 10a repeats transmitting a transmission signal including its own ID and trajectory information (No in S120).

[0058] At a given time T W If the group management unit 12a receives a response signal dID as a group registration message from another wireless device before the time has elapsed (Yes in S120), the group management unit 12a generates a list of IDs of the other wireless devices that have issued response signals (group list) based on the received response signal dID and stores the list in the storage unit 15a (S130). In the example shown in Fig. 10, response signals dID are transmitted from the wireless devices 1b to 1d, but no response signal is issued from the wireless device 1e. This means that the wireless device 1e has been determined not to belong to a group because there is a low correlation between the trajectory information of the wireless device 1a and the trajectory information of the wireless device 1e.

[0059] When the group list is generated, the wireless interface 10a transmits a group acknowledgement (ACK) to the other wireless devices that have issued response signals (S140). This group acknowledgement indicates that the wireless device has joined the group as a group member. In the example shown in Fig. 10, the wireless device 1a transmits a group acknowledgement to the wireless devices 1b to 1d that have transmitted the response signals dID.

[0060] At this stage, the wireless device 1a becomes the group leader GL of the group whose members are the wireless device 1a itself and the other wireless devices 1b to 1d. The group management unit 12a transmits a tracking area update message including a list of IDs of the wireless device 1a itself and the other wireless devices 1b to 1d that are group members to the base station eNB (S150). The base station eNB transfers the received group update information to the core network CN. The core network CN is the backbone of the network and includes a database that manages wireless devices that belong to the tracking network TA, so it updates the tracking area TA information in the database using the received group update information. When the update of the tracking area is completed, the core network CN sends update acceptance information to the base station eNB, and the base station eNB transfers the update acceptance information to the wireless device 1a.

[0061] When the update acceptance information is received, the wireless interface 10a transfers the update acceptance information to the other wireless devices 1b to 1d that are group members (S160). When the update acceptance information is received, the other wireless devices 1b to 1d become aware that they have been registered as group members.

[0062] In this embodiment, the wireless device that becomes the group leader GL transmits its own trajectory information to the other wireless devices, and grouping is performed based on the response signal returned by the wireless device that is determined to be suitable for grouping based on the trajectory information. Therefore, since it is highly likely that the grouped wireless devices move along a similar trajectory, the core network CN appropriately manages the movement. In addition, the grouping procedure is triggered by the group leader GL issuing its own trajectory information, so that the grouping can proceed autonomously without the involvement of the core network CN or the like. In addition, since the wireless device that becomes the group leader GL after grouping transmits a tracking area update message, it is possible to suppress the concentration of communication due to the update of location information, etc.

[0063] Next, the operation of the wireless device 1b will be described as a representative of the wireless devices 1b to 1e that are group members in the grouping procedure.

[0064] The positioning unit 13b acquires information on the base station cell to which the wireless device 1b belongs and the tracking area TA via the wireless interface 10b. The positioning unit 13b associates the acquired information on the tracking area TA with time information to generate a trajectory ρ y (k) is generated and stored in the storage unit 15b (S200). y (k) constitutes trajectory information regarding the movement of the wireless device 1b.

[0065] The wireless interface 10b receives the trajectory information (trajectory ρ x When the grouping message including the trajectory information (trajectory ρ x (k)) and the own trajectory information (trajectory ρ y Based on (k), the correlation C between the wireless device 1a that transmitted the grouping message and itself is x,y (k) is calculated (S220).

[0066] Calculated correlation C x,y If (k) is "0" (No in S230), the group determination unit 14b does not generate a response signal, and the wireless interface 10b ends the process without transmitting anything. This is because the correlation with the wireless device 1a is low, and it is not appropriate for them to belong to the same group. In the example shown in Fig. 10, this corresponds to the wireless device 1e, and the process ends without transmitting a response signal dID.

[0067] Calculated correlation C x,yIf (k) is "1" (Yes in S230), the group determination unit 14b generates a response signal dID, and the wireless interface 10b transmits the response signal dID to the wireless device 1a (S240). This means that the wireless device 1b has a high correlation with the wireless device 1a, and it is appropriate for them to belong to the same group. In the example shown in Fig. 10, the wireless devices 10b to 10d transmit response signals dID to the wireless device 1a.

[0068] After transmitting the response signal dID, the wireless interface 10b waits for the reception of a group acknowledgement (S250). w If the group acknowledgment is not received within this period, the wireless interface 10b retransmits the response signal dID (No in S250).

[0069] When receiving the group reception notification (Yes in S250), the group determination unit 14b stores the ID of the wireless device 1a as the group leader GL in the storage unit 15b (S260). This allows the wireless device 1b to know that it has joined a group in which the wireless device 1a is the group leader GL.

[0070] After that, the wireless interface 10b receives the tracking area update acceptance information (S270). This allows the group determination unit 14b to know that it has been recorded in the core network CN that the wireless device 1b belongs to a group whose group leader GL is the wireless device 1a.

[0071] Through this series of operations, a group is formed with the wireless device 1a as the group leader GL and the wireless devices 1a to 1d as the group members, and the grouping information is recorded in the core network CN. This enables the core network CN to track the locations of the wireless devices 1a to 1d, and enables the wireless devices 1a to 1d to receive calls from the core network.

[0072] (Assessment of correlation) With reference to FIG. 11, the determination of correlation between M2M devices in the embodiment will be described. When two devices take a similar movement path (trajectory) in terms of time and location, the two devices are defined as being correlated. For example, when a device m x and device m y The trajectories of J x , J y Then, it can be expressed as follows:

number

number

[0073] The trajectory ρ(k) is represented as the set of k tracking areas TA visited by the device.

number

[0074] time t i TA i Device m x ρ i x Then, the correlation between two users can be estimated as follows:

number

number

[0075] M2M Devices x is that ρ x (k) is broadcast to the neighboring devices. At this time, device m x declares itself to be the group leader. y is the device m x ρ broadcast by x Receive (k).

[0076] Device m y is the device m x If C=1, then the correlation with device m y is the device m x It is determined that there is a correlation between device m and the moving object. y sends the response signal ID to device m x Send to join the group.

[0077] When a group enters a new tracking area TA, only the device that is the group leader GL performs registration (TAU procedure). The tracking area update message that the device that is the group leader GL sends to the core network CN contains the IDs of the member devices. Grouping is performed at a predetermined timing T update The grouping procedure is performed every time. At that time, any device that was a member may start the grouping procedure. When the grouping procedure is re-executed, the group leader GL at that time sends updated registration information to the core network CN.

[0078] The core network CN records the location information of each device in the group in units of a tracking area TA. When a call or data arrives for a specific device, the core network CN transfers it to the device via the corresponding tracking area TA.

[0079] (Evaluation of the embodiment) The embodiment was evaluated using two methods. The first method was the Signaling Reduction Ratio (SSR), which is expressed by the following formula:

number

[0080] The second is the page miss ratio (PMR), which is expressed by the following formula:

number

[0081] Simulations were performed for two movement models. The first movement model is a random walk model. In the random walk model, devices move independently and randomly to adjacent tracking areas TA, and there is no correlation between the movements of individual devices. The second movement model is a planned transportation model. In the transportation model, multiple devices are loaded onto a moving object such as a vehicle or container. The moving object can individually determine the tracking area TA to move to and the duration of stay, but moves along a predetermined trajectory such as on a road. There is a strong correlation between the movements of devices loaded onto the same moving object.

[0082] (Effect of K) Figure 12 shows the impact of the index K. Index K is the criterion for grouping. When two devices are grouped, the number of past changes in the tracking area TA that they have in common is the index K. A large index K indicates that devices with higher correlation are grouped together. A large index K also means fewer dropouts, and the PMR value is smaller. In the random walk model, when index K is large, the SRR is also small, and there is little benefit to grouping SRR.

[0083] (T update (Effect of Fig. 13 shows the influence of the grouping update timing. In the transportation model, all devices update their groups at each update timing. As shown in Fig. 13, in the embodiment, the PMR is small in both the random walk model and the transportation model, and it can be seen that the mechanism of periodically updating the grouping is working effectively.

[0084] (Effect of average visit time) Fig. 14 shows the influence of the average stay time, which is the average of the stay time in a certain tracking area TA. If the average stay time is short, the device frequently changes the tracking area TA. As shown in Fig. 14, in the embodiment, regardless of the length of stay time in the tracking area TA, the PMR is a small value.

[0085] (Effect of paging message arrival rate) Figure 15 shows the effect of the arrival rate of the paging from the core network CN. As shown in Figure 15, the paging message arrival rate is not related to the grouping registration. In the embodiment, the PMR is small regardless of the paging message arrival rate, which is because the departure detection function is working effectively.

[0086] (Maximum effect of SSR at acceptable PMR) As shown in Fig. 16, the index K and the communication timing Tupdate By configuring it appropriately, you can significantly reduce the number of registration messages.

[0087] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0088] 1a to 1e: wireless devices, 10a to 10b...wireless interface, 11a to 11b... terminal communication unit, 12a~12b…Group Management Department, 13a to 13b...positioning unit, 14a to 14b... group determination unit, 15a~15b...Storage section, eNB...Base station, CN: Core network, TA...Tracking area.

Claims

1. A wireless device connected to a base station in a core network that manages a location of a connection partner of the base station in units of a tracking area including a communication area of ​​the base station, comprising: a first radio interface for communicating with the core network via the base station; a second wireless interface for communicating with other wireless devices located in the common tracking area; a positioning unit that generates trajectory information of the user's own movement based on past position information of the user; generating a transmission signal including the trajectory information at a predetermined timing and transmitting the transmission signal to the other wireless device via the second wireless interface; receiving, via the second wireless interface, a response signal sent back from the other wireless device in response to the transmission signal; generating a group list including IDs of the other wireless devices that have returned the response signals; transmitting a request for registration of location information of the wireless device itself and the other wireless device that has returned the response signal to the core network via the first wireless interface based on the group list; Group Management Department and receiving a signal including trajectory information of a movement of the other wireless device from the other wireless device via the second wireless interface; generating correlation information indicating a correlation between the trajectory information of the own movement and the trajectory information of the other wireless device based on the trajectory information of the movement of the own wireless device and the trajectory information of the movement of the other wireless device; determining whether the wireless device belongs to a group including the other wireless device based on the correlation information; If the result of the determination indicates that the device belongs to the group, the device transmits a response signal including its own ID via the second wireless interface. A group determination unit; A wireless device comprising:

2. A wireless device connected to a base station in a core network that manages a location of a connection partner of the base station in units of a tracking area including a communication area of ​​the base station, comprising: a first radio interface for communicating with the core network via the base station; a second wireless interface for communicating with other wireless devices located in the common tracking area; a positioning unit that generates trajectory information of the user's own movement based on past position information of the user; generating a transmission signal including the trajectory information at a predetermined timing and transmitting the transmission signal to the other wireless device via the second wireless interface; receiving, via the second wireless interface, a response signal sent back from the other wireless device in response to the transmission signal; generating a group list including IDs of the other wireless devices that have returned the response signals; transmitting a registration request for location information of the wireless device itself and the other wireless device that has returned the response signal to the core network via the first wireless interface based on the group list; Group Management Department and A wireless device comprising:

3. A wireless device connected to a base station in a core network that manages a location of a connection partner of the base station in units of a tracking area including a communication area of ​​the base station, comprising: a first radio interface for communicating with the core network via the base station; a second wireless interface for communicating with other wireless devices located in the common tracking area; a positioning unit that generates trajectory information of the user's own movement based on past position information of the user; receiving a signal including trajectory information of a movement of the other wireless device from the other wireless device via the second wireless interface; generating correlation information indicating a correlation between the trajectory information of the own movement and the trajectory information of the other wireless device based on the trajectory information of the movement of the own wireless device and the trajectory information of the movement of the other wireless device; determining whether the wireless device belongs to a group including the other wireless device based on the correlation information; If the result of the determination indicates that the device belongs to the group, the device transmits a response signal including its own ID via the second wireless interface. A group determination unit; A wireless device comprising:

4. 4. The wireless device according to claim 1, wherein the positioning unit acquires, as the location information, identification information of a tracking area including a communication area of ​​the base station connected via the first wireless interface.

5. 4. The wireless device according to claim 1, wherein, after transmitting the response signal, the group determination unit receives update acceptance information indicating that the location information of the wireless device has been registered in the core network.

6. 3. The wireless device according to claim 1, wherein the group management unit regenerates the transmission signal after a predetermined period of time has elapsed since transmitting the registration request, and transmits the transmission signal to the other wireless devices via the second wireless interface.

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