JP2020096218A - Mobile communication network control device, proximity information server, mobile communication network, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for appropriately updating proximity information. A mobile communication network control device that controls to provide relay communication between a first user device connected to a first base station and a second user device connected to a second base station is a first. When a relay communication establishment request is received from the user device and the establishment request is received, the proximity information server receives the first proximity information including information about one or more second user devices located within a predetermined range from the first user device. Acquire and acquire radio quality information between the first user device and the second user device from one or more second user devices based on the first proximity information, and one or more based on the radio quality information. It is determined whether or not there is a relay terminal that provides relay communication from the second user equipment of the above, and if it is not determined that the relay terminal does not exist, proximity information different from the first proximity information is sent to the proximity information server. Request. [Selection diagram] Fig. 1

Description

The present invention relates to a relay communication technique using a user equipment in a mobile communication network.

In the fifth-generation mobile communication system (5G), under the control of a macrocell base station (large cell station), a non-standalone one that accommodates a terminal in a small cell base station (small cell station) capable of large-capacity communication. (NSA) configuration is assumed. In the NSA configuration, relay communication is used to accommodate the traffic of terminals outside the communication range of the small cell station in the small cell station. The relay communication does not exist in the small cell provided by the small cell station, but the terminal (remote user equipment) existing in the macro cell provided by the large cell station does not exist in the small cell (candidate). It is realized by relay connection to a small cell station via at least one (relay terminal) of user equipment). As a result, the number of terminals accommodated in the large cell station can be increased. In addition, by considering the wireless quality information between the terminals and selecting the relay terminal from the candidate user apparatuses located in the small cell, the effect of accommodating traffic in the small cell station by the relay communication can be enhanced.

Until now, as a method of selecting a relay terminal for relay communication in consideration of wireless quality information, a remote user apparatus transmits a notification signal, receives a feedback signal from a candidate user apparatus that has received the notification signal, and performs relay communication. A method of selecting a relay terminal for establishing has been proposed. However, in a congested environment in an urban area, the probability that the notification signal transmitted by the remote user equipment and the feedback signal from the candidate user equipment collide is high, and the remote user equipment efficiently collects the wireless quality information and relay terminal Difficult to choose.

On the other hand, as another method of selecting a relay terminal for relay communication in consideration of wireless quality information, a mobile communication network including a large cell station transmits a notification signal transmitted by a remote user device or a candidate user device. Central control has been proposed to control the radio resources for the feedback signal. This makes it possible to avoid collision of the notification signal and the feedback signal, so that it is possible to efficiently collect the wireless quality information even in a congested environment. However, the transmission of the radio resource control signal for collecting radio quality information by the large cell station shares resources for other communication of the large cell station, and therefore, depending on the number of terminals, most of the communication resources of the large cell station are The radio resource control signal may occupy and deteriorate the communication performance of the large cell station.

For example, in Non-Patent Document 2, by using the proximity information (Non-Patent Document 1) defined in LTE and limiting the transmission destination of the radio resource control signal to a candidate user device existing in the proximity area of the remote user device, Techniques have been proposed to reduce the amount of radio resource control signals. According to this, the Radio Resource Control Configuration (RRC Conf) that instructs the candidate user apparatus to measure the broadcast signal of the remote user apparatus and the Device-to-device Measurement Report (D2D MR) that reports the measurement result from the candidate user apparatus. Signaling for the can be reduced.

3GPP TS23.303; Technical Specification Groups Services and System Aspects; Proximity-based services (ProSe); Stage 2 (Release 15). Koichiro Kitagawa, et al., "Study on signal amount reduction method for relay communication between 5G terminals", Proc. of the 26th multimedia communication and distributed processing workshop, 90-96, October 31, 2018.

However, when the update of the information (proximity) about the positions of the remote user apparatus and the candidate user apparatus is slow, and the like, the proximity of the mobile communication network and the actual remote user apparatus and the candidate user apparatus are compared. Proximity may vary. In such a case, a relay terminal will be selected from the candidate user apparatus list included in the incorrect proximity information, and an appropriate relay terminal may not be selected.

The present invention provides a technique for appropriately updating proximity information.

According to one aspect of the present invention, a controller of a mobile communication network for controlling to provide relay communication between a first user equipment connected to a first base station and a second user equipment connected to a second base station. Is a reception unit that receives a request for establishing relay communication from the first user device, and one or more second users located within a predetermined range from the first user device from the proximity information server when receiving the request for establishment. A first acquisition unit that acquires first proximity information including information about a device, and one or more second user devices based on the first proximity information, from the first user device and the second user device. Second acquisition means for acquiring wireless quality information between the two, and whether or not there is a relay terminal that provides the relay communication from among the one or more second user devices based on the wireless quality information. Determination means for determining, and requesting means for requesting proximity information different from the first proximity information to the proximity information server when the determination means does not determine that the relay terminal exists, And

According to the present invention, it is possible to provide a technique for appropriately updating proximity information.

The figure which shows the mobile communication network which concerns on one Embodiment. FIG. 6 is a sequence diagram illustrating proximity-based signaling according to one embodiment. FIG. 6 is a sequence diagram illustrating proximity-based signaling according to one embodiment. The sequence diagram of the proximity information update process which concerns on 1st Embodiment. The sequence diagram of the proximity information update process which concerns on 2nd Embodiment. The figure which shows the multi-layer proximity degree which concerns on 3rd Embodiment. The sequence diagram of the proximity information update process which concerns on 3rd Embodiment.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. The following embodiments are exemplifications, and the present invention is not limited to the contents of the embodiments. Further, in each of the following drawings, components that are not necessary for explaining the embodiment are omitted from the drawings.

<PF-based communication control>
FIG. 1 is a configuration diagram of a mobile communication network for explaining the present embodiment. The mobile communication network includes a large cell station 101, small cell stations 111 and 112, a network device 121, and a Proximity-based Service (ProSe) Function Server (PFS) 122 as components.

The large cell station 101 is a macro base station that has a coverage (macro cell) 102 and controls PF-based communication via the small cell station 111 or 112. The small cell stations 111 and 112 have small coverages (small cells) 113 and 114 as compared with the large cell station 101, and are 5G-compatible small base stations capable of accommodating relay communication.

The network device 121 is a control device having a function of Access and Mobility Function (AMF) that manages mobility of user terminals (UE) accommodated in the large cell station 101 and the small cell stations 111 and 112, for example. In one example, the network device 121 may have another function such as a Session Management Function (SMF) that manages session management. The PFS 122 is a proximity information server that manages the proximity of UEs or the position of a UE within a coverage area.

Here, an operation in which the mobile communication network selects a relay terminal from UE 131 and UE 132 which are candidate user devices in order for UE 141 to perform relay communication will be described. In the present specification, a UE located outside the small cell and requesting relay communication is a remote user apparatus (remote UE), a UE located in a small cell and located in a predetermined range from the remote user apparatus is a candidate user apparatus. (Candidate UE). A UE that provides relay communication to a remote user equipment is called a relay terminal.

The UEs 131 and 133 are UEs located within the coverage 113 of the small cell station 111, and the UEs 132 and 134 are UEs located within the coverage 114 of the small cell station 112. The UEs 131 and 132 are located within the proximity range 142 of the remote UE 141. That is, the UE 131 is a candidate user device located in the small cell 113 provided by the small cell station 111, and the UE 132 is a candidate user device located in the small cell 114 provided by the small cell station 112.

The UE 141 is a remote user equipment located in the macro cell 102 of the large cell station 101 but not in the small cells 113 and 114.

In FIG. 2, a solid line connecting the large cell station 101, the small cell stations 111 and 112, and the network device 121, and a solid line connecting the network device 121 and the PFS 122 indicate communication lines connecting the components of the mobile communication network. ing. Note that, in FIG. 2, other communication lines or components are not shown for simplification of the drawing. For example, there may be more than two small cell stations, and one network device 121 may be connected to two or more large cell stations 101.

Further, the network device 14 can be realized not by one device but by a plurality of devices distributed and arranged at a plurality of places. The present invention is not limited to the 5G system, but can be applied to a mobile communication system according to any standard.

Here, with reference to FIG. 2, a sequence in which the mobile communication network controls relay communication will be described.

First, in S201, the remote UE 141 transmits an establishment request (session request) for requesting establishment or switching of a relay communication session to the large cell station 101. The large cell station 101 that has received the establishment request transfers the request to the network device 121 in S202.

Upon receiving the session request in S203, the network device 121 transmits a proximity information request (Proximity Information Request) to the PFS 122. The PFS 122 that has received the proximity information request relates to a candidate user device located within a predetermined range (for example, the proximity range 145 of FIG. 1) from the remote UE 141 that has transmitted the session request as a proximity information response (Proximity Information Response) in S204. The information is transmitted to the network device 121.

Subsequently, in S205, the network device 121 instructs the large cell station 101 to transmit a Radio Resource Control Reconfiguration (RRC Reconf) signal to the candidate user devices included in the proximity information response received in S204. The large cell station 101 having received the transmission instruction of the RRC Reconf signal transmits the RRC Reconf signal to the candidate user apparatuses 131 and 132 directly or via the small cell stations 111 and 112 in S206. The RRC Reconf signal includes information indicating at least one of a radio resource for transmitting a broadcast signal from the remote UE 141 and a radio resource for transmitting radio quality information from the candidate user apparatus to the large cell station 101. The candidate user apparatuses 131 and 132 that have received the RRC Reconf signal receive the notification signal transmitted from the remote UE 141 in S207. That is, the RRC Reconf signal transmitted in S206 is a request for measuring the radio quality between the remote user equipment and the candidate user equipment for the candidate user equipment. Subsequently, in S208, the candidate user devices 131 and 132 inform the large cell station 101 of a device-to-device measurement report (D2D MR) signal including information about the radio quality between the remote UE 141 and each of the candidate user devices 131 and 132. To send. The RRC Reconf signal and the D2D MR signal are transmitted for each terminal in a radio resource area (Shared channel) for data transmission.

The large cell station 101 having received the D2D MR signal transmits a Relay UE Report including the D2D MR to the network device 121 in S209 based on the D2D MR received in S208.

After that, the network device 121 selects a relay terminal for providing relay communication based on the received Relay UE Report, and transmits information on the relay terminal to the large cell station 101 in S210. The large cell station 101 transmits a Relay UE Configuration signal to the selected relay terminal in S211. The relay terminal establishes communication with the remote UE 141 in S212, and performs relay communication in S213.

As described above, by transmitting/receiving the RRC Reconf signal and the D2D MR signal to/from a limited number of candidate user apparatuses based on the proximity, the mobile communication network reduces signaling while A relay terminal can be selected to provide relay communication to the remote user equipment.

Here, when the proximity information provided by the PFS 122 to the network device 121 is old, the remote UE 141 moves, the radio quality between the remote UE 141 and the candidate user device changes significantly, and the mobile communication network performs relay communication to the remote UE 141. It may not be possible to select a relay terminal to provide. Here, with reference to FIG. 3, the radio quality between the candidate user equipment and the remote UE 141 included in the proximity information response provided by the PFS 122 in S204 of FIG. 2 changes, and the large cell station 101 selects the relay terminal. A process that may occur when the process cannot be performed will be described. The description of the same processing as that in FIG. 2 is omitted.

In S204, if the wireless environment between the candidate user equipment included in the proximity information response provided by the PFS122 and the remote UE 141 has changed significantly, in S207, the candidate user equipment cannot receive the notification signal from the remote UE 141. Good. In such a case, the candidate user apparatus does not transmit the D2D MR signal in S208 because it waits until the notification signal is detected. Alternatively, the candidate user equipment transmits a D2D MR signal notifying that the broadcast signal has not been detected in the RRC Reconf instructed in S206.

Subsequently, the large cell station 101 transmits to the network device 121 a notification indicating that information necessary for selecting a relay terminal has not been collected. Alternatively, the large cell station 101 holds the notification of S309 until it receives D2D MRs from all candidate user devices.

The network device 121 transmits the RRC Reconf in S205 and does not receive from the large cell station 101 the information capable of selecting a relay terminal for providing relay communication within a predetermined period, or the wireless quality information from the candidate user device. When a notification indicating that the session requests have not been collected is received in S309, a Session establishment failure signal for rejecting the session request is transmitted to the large cell station 101 in S310. Upon receiving the session establishment failure signal, the large cell station 101 notifies the remote UE 141 in S311 that the relay communication establishment process is to be stopped.

<First Embodiment>
A first embodiment will be described with reference to FIG. 4 in which the network device 121 that has determined that relay communication cannot be provided transmits a recovery signal for triggering the update of the proximity information of the remote user device 121. Note that the same reference numerals are used for the same processes as those in FIGS. 2 and 3, and description thereof will be omitted.

In S201, the remote UE 141 transmitted the session request, but in S204, the PFS122 provided inaccurate proximity information, and thus it is indicated in S309 that the large cell station did not collect the wireless quality information from the candidate user apparatus to the network apparatus. A case where the notification is transmitted will be described.

In this case, the network device 121 according to the present embodiment transmits the recovery signal to the PFS 122 in S410. Upon receiving the recovery signal, the PFS 122 determines that different proximity information is required to select the relay terminal. In this case, the PFS 122 determines that the proximity information needs to be updated.

Upon receiving the recovery signal, the PFS 122 transmits a proximity measurement request to the large cell station 101 in S411. In S412, the large cell station 101 instructs the UE in the macro cell including at least the remote UE 141 to measure the proximity. Subsequently, the large cell station 101 receives the D2D MR from the UE that has instructed the proximity measurement in S413, and transmits the latest proximity information to the PFS 122 in S414. The PFS 122 received from the large cell station 101 in S414 updates the proximity information, provides the updated proximity information to the network device 121 in the same manner as in S204, and selects S205 to select the relay terminal for providing the relay communication. The processing of S208 is executed. The large cell station 101 may transmit information necessary for creating the latest proximity information to the PFS 122 in S414, and the PFS 122 may generate the proximity information based on the received information.

As described above, when the selection of the relay terminal fails, the network device 121 determines that the UE has moved and the wireless environment has changed after the PFS 122 acquires the proximity information, and transmits the recovery signal to the PFS 122. By causing the FS 122 to update the proximity information and providing the updated proximity information, it is possible to select a relay terminal that provides relay communication.

<Second Embodiment>
In the first embodiment, the PFS 122 can update the proximity information by receiving, from the network device 121, a recovery signal indicating that different proximity information is requested because the selection of the relay terminal has failed. In the second embodiment, a PFS 122 that receives a recovery signal from the network device 121 and determines whether to update proximity information will be described with reference to FIG. Note that the same reference numerals are used for the same processes as those in FIGS. 2 to 4, and the description thereof will be omitted.

Upon receiving the recovery signal from the network device 121 in S410, the PFS 122 advances the process to S511, and performs a process (update determination process) of determining whether the proximity information needs to be updated.

In one example, the update determination process performs the update determination process based on whether it is within a predetermined time. For example, the PFS 122 may determine that the proximity information needs to be updated when 1 second or more has elapsed since the PFS 122 immediately updated the proximity information. If one second or more has not elapsed since the proximity information was updated immediately before, the proximity does not change, and the selection of the relay terminal fails due to the radio environment around the UE such as noise intensity. Therefore, it may be determined that the update of the proximity information is unnecessary.

In addition, in one example, the update determination process is performed based on the speeds or the relative speeds of the remote UE 141 and the candidate user devices 131 and 132. For example, the UE may include its own speed in the D2D MR and transmit to the large cell station 101. In such a case, the large cell station 101 may transmit the information regarding the speed of any of the UEs in the macro cell to the PFS 122 by including it in the recovery signal. Based on the received information about the speed, the PFS 122 determines that the update of the proximity information is unnecessary if the remote user equipment in the macro cell is at a predetermined speed or higher, and if the speed is less than the predetermined speed, May determine that the proximity information needs to be updated. Further, the PFS 122 transmits the RRC Reconf signal to the candidate user equipment when the candidate user equipment in the macro cell is at a predetermined speed or higher, and does not transmit the RRC Reconf signal when the candidate user equipment in the macro cell is less than the predetermined speed. The proximity information response may be changed as follows. That is, in S511, the necessity of updating the proximity information may be determined for each UE.

When the PFS 122 determines in S511 that the proximity information can be updated, the PFS 122 updates the proximity information by the same process as the process described with reference to S411 to S414 in FIG. On the other hand, when the PFS 122 determines in S511 that updating of the proximity information is unnecessary, the PFS 122 transmits an update interruption signal notifying the large cell station 101 of rejection of the update of the proximity information in S512. The large cell station 101 having received the update interruption signal in S512 transmits the update interruption signal to the remote UE 141.

<Third Embodiment>
In the first and second embodiments, the proximity information can be updated when a relay terminal located within the proximity range cannot be selected in order to provide relay communication. In an example, when a relay terminal for providing relay communication cannot be selected, the proximity range may be changed and it may be determined whether the relay terminal can be selected from the candidate user devices located in the changed proximity range. In the third embodiment, an operation of a mobile communication network capable of increasing or decreasing the number of candidate user devices by expanding the proximity range until selecting a relay terminal will be described.

A proximity range including a plurality of layers will be described with reference to FIG. In FIG. 6, four layers shown as layers 601 to 604 are set as the proximity from the remote UE 141. The layer 601 is closest to the remote UE 141 and leaves the remote UE 141 in the order of layers 602, 603, 604. The proximity to the remote UE 141 is not limited to the physical distance, and may be determined according to radio wave loss or RSSI, and thus the layers 601 to 604 do not have to be circular.

For example, a UE whose reception strength of the notification signal transmitted by the remote UE 141 is larger than -30 dBm belongs to the layer 601, and a UE whose reception strength is equal to or smaller than -30 dBm and larger than -40 dBm is a candidate user apparatus belonging to the layer 602. A UE whose reception strength of the broadcast signal is -40 dBm or less and greater than -50 dBm belongs to layer 603, and a UE whose reception strength is -50 dBm or less and greater than -60 dBm is a candidate user apparatus belonging to layer 604. UEs below -60 dBm are not candidate user equipments.

Next, with reference to FIG. 7, a process for selecting a relay terminal from a proximity range having a plurality of layers will be described. It should be noted that the same reference numerals are used for the same processes as those in FIGS. 2 to 5, and description thereof will be omitted.

First, the PFS 122, which has received the proximity information request in S203, transmits the proximity information regarding the candidate user apparatus existing in the narrowest layer (for example, the layer 601 in FIG. 6) to the large cell station 101 in S704.

After that, the network device that has received the notification that the selection of the relay terminal has failed in S309 transmits a recovery signal that notifies that the selection of the relay terminal has failed in S410 to the PFS 122. In S711, the PFS 122 transmits to the large cell station 101 proximity information related to candidate user devices existing in the second narrowest layer (eg, the layer 602 in FIG. 6). The processing of S712 to S715 is similar to that of S205 to S208, and therefore description thereof is omitted.

In addition, as shown in FIG. 6, when the candidate user apparatus does not exist in the layer 602, the PFS 122 transmits the proximity information of the candidate user apparatus belonging to the layer 603 without transmitting the proximity information of the layer 602. Good.

Further, in one example, the PFS 122 may set a layer in terms of the number of candidate user devices. For example, the PFS 122 that has received the proximity information request in S203 has, for example, 10 candidates in descending order of proximity to the remote UE 141, so that the number of candidate user devices to which the large cell station transmits the RRC Reconf signal is 10 or less. A proximity information response for the user device may be sent at S704. After that, the PFS 122 that has received the recovery signal from the network device 121 in S410 may transmit the proximity information responses of the 20 candidate user devices in S711 in descending order of proximity to the remote UE 141.

This can limit the number of candidate user equipments that transmit the RRC Reconf signal.

As described above, according to the present embodiment, when the relay terminal for providing the relay communication cannot be selected, the number of candidate user devices can be increased or decreased by changing the proximity range.

<Other embodiments>
The first to third embodiments can be arbitrarily combined. For example, the PFS 122 that has received the recovery signal may determine whether to update the proximity information or change the proximity range for selecting the relay terminal.

Note that at least one of the network device 121 and the PFS 122 according to the present invention can be realized as one device or can be realized by a plurality of devices that can communicate with each other via a network. Further, at least one of the network device 121 and the PFS 122 can be realized by a program that causes a computer to operate as at least one of the network device 121 and the PFS 122. These computer programs can be stored in a computer-readable storage medium or can be distributed via a network.

101: Large cell station, 102: Macro cell, 111, 112: Small cell station, 113, 114: Small cell, 121: Network device, 122: PFS, 131, 132, 133, 134, 141: UE, 142: Proximity range

Claims (9)

A controller of a mobile communication network for controlling to provide relay communication between a first user equipment connected to a first base station and a second user equipment connected to a second base station,
Accepting means for accepting a relay communication establishment request from the first user device;
A first acquisition unit that, upon receiving the establishment request, acquires first proximity information from the proximity information server, the first proximity information including information on one or more second user devices located within a predetermined range from the first user device;
Second acquisition means for acquiring wireless quality information between the first user device and the second user device from one or more second user devices based on the first proximity information;
Determination means for determining whether or not there is a relay terminal that provides the relay communication from among the one or more second user devices based on the wireless quality information;
Requesting means for requesting proximity information different from the first proximity information to the proximity information server when the determining means does not determine that the relay terminal exists;
A control device comprising: A proximity information server that communicates with a controller of a mobile communication network that controls to provide relay communication between a first user equipment connected to a first base station and a second user equipment connected to a second base station, ,
Storage means for storing information relating to the degree of proximity between the first user device and the second user device;
Providing means for providing first proximity information in response to a request from the control device for information regarding one or more second user devices located within a predetermined range from the first user device;
Receiving means for receiving a request for second proximity information different from the first proximity information after providing the first proximity information from the control device;
A proximity information server comprising: The proximity information server according to claim 2, further comprising a measurement requesting unit that transmits a proximity measurement request when the receiving unit receives the second proximity information request. The proximity is created by the proximity information server based on at least one of the distance between the first user device and the second user device and the reception intensity of the notification signal transmitted by the first user device. The proximity information server according to claim 2 or 3, characterized in that. Second determining means for determining whether or not to provide the second proximity information when the receiving means receives the request for the second proximity information;
When it is determined that the second proximity information is not provided, a transmission unit that transmits an update interruption signal,
The proximity information server according to any one of claims 2 to 4, further comprising: When the receiving unit receives the request for the second proximity information, the second proximity information including information about the second user apparatus having a lower proximity than the second user apparatus included in the first proximity information is provided. The proximity information server according to claim 2, further comprising means. A mobile communication network for providing relay communication between a first user equipment connected to a first base station and a second user equipment connected to a second base station,
Storage means for storing information relating to the degree of proximity between the first user device and the second user device;
Accepting means for accepting the relay communication establishment request from the first user device;
A first acquisition unit that, when receiving the establishment request, acquires first proximity information including information about the second user device located within a predetermined range from the first user device, from the storage unit;
Second acquisition means for acquiring, from the second user device, wireless quality information regarding wireless quality between the first user device and the second user device based on the first proximity information;
Determination means for determining whether or not there is a relay terminal that provides the relay communication among the second user devices based on the wireless quality information;
Requesting means for requesting second proximity information different from the first proximity information when the determining means does not determine that the relay terminal exists;
A mobile communication network comprising: A program that causes a computer to function as the control device according to claim 1. A program that causes a computer to function as the proximity information server according to claim 2.

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