JP7520260B2 - COMMUNICATION SYSTEM, BASE STATION, MOBILE STATION, AND COMMUNICATION METHOD - Google Patents

Description

The present disclosure relates to a communication system, a base station, a mobile station, a control circuit, a storage medium, and a communication method that perform time-synchronized communication.

In recent years, systems have been developed that connect multiple industrial devices to a network and operate them in cooperation. Such systems are used in a wide range of applications. For example, a system has been put into practical use in which multiple robot arms are connected to a network in a factory production line, and they perform manufacturing in cooperation with time synchronization based on commands from a specific control device. There are many options for such networks, and multiple standards are provided under names such as fieldbus and industrial Ethernet (registered trademark). By connecting multiple devices to a network, it is possible to respond to emergencies and share sensor information, making it possible to build a safe and efficient system. Fieldbuses and industrial Ethernets require strict time synchronization between devices, so they are designed to minimize delays in signal transmission, and a standard called TSN (Time Sensitive Networking) that performs time synchronization is widely used.

Meanwhile, development of time-synchronized communication using wireless communication technology, known as Time Sensitive Communication (TSC), has begun to accommodate small-lot, high-mix production and to incorporate not only production lines but also mobile objects such as AGVs (Automatic Guided Vehicles) into networks. One example is the Fifth Generation System (5GS), which is being considered by the Third Generation Partnership Project (3GPP), which is standardizing mobile communication systems.

For example, Patent Document 1 discloses technology for a TSC network consisting of a core device, a base station which is a wireless access device, a mobile station which is a terminal device, a TSN translator, etc. Figure 2 of Patent Document 1 shows a configuration in which an end station which is a network component device on a TSN working domain outside the core device and an end station connected to a terminal device are connected via 5GS, and time-synchronized communication is performed between the two devices.

International Publication No. 2021/059538

When connecting synchronously operating end stations using 5GS and other wired networks, 5GS, which provides time synchronization services, operates as a virtual TSN bridge from the end station's perspective. The virtual TSN bridge provided by 5GS is expected to keep delay times constant by providing a buffer in which a TSN translator can store data signals.

Here, the terminal device to which the end station is connected can construct a local TSC network by utilizing the direct communication function between the terminal devices. Such a direct communication function between the terminal devices corresponds to a function called SL (Side Link) in 3GPP. Resource allocation in SL is not necessarily instructed by the scheduler of the base station, and each terminal device selects resources autonomously and decentrally while watching the resource usage status of the surrounding terminal devices. Therefore, the delay time may change significantly depending on the communication status of the surrounding terminal devices. In addition, the 3GPP standard requires that the resources used in SL be reselected at regular intervals, so the delay time may change periodically. It is also possible to calculate the worst value of the delay time of SL and provide a buffer in which the TSN translator can hold the data signal for a long time, but there is a problem that the fluctuation amount of the delay time of SL increases compared to the communication between the base station and the terminal device, which significantly deteriorates the efficiency of the network.

The present disclosure has been made in consideration of the above, and aims to obtain a communication system capable of performing efficient time-synchronized communication even when the delay time in the mobile communication system fluctuates.

In order to solve the above-mentioned problems and achieve the object, the present disclosure provides a communication system constituting a part of a time-synchronized network. The communication system includes a network control device that manages the time-synchronized network, a core device that provides a network function of a mobile communication system, a relay mobile station that can communicate directly , a base station that controls communication between the core device, a relay mobile station that is a mobile station that can communicate directly with the base station, and a remote mobile station that is a mobile station that can communicate indirectly with the base station via the relay mobile station . When the base station allocates resources in communication with the relay mobile station , the base station notifies the network control device of information on time of the allocated resources as delay time information, when the relay mobile station allocates resources in communication with the remote mobile station, the base station notifies the network control device of information on time of the allocated resources as delay time information, and when the remote mobile station allocates resources in communication with the relay mobile station, the remote mobile station notifies the network control device of information on time of the allocated resources as delay time information .

The communication system disclosed herein has the advantage of being able to perform time-synchronized communication efficiently even when the delay time in the mobile communication system fluctuates.

FIG. 1 is a diagram showing a configuration example of a communication system according to a first embodiment; A diagram showing an example of a communication system that performs time-synchronized communication using 5GS. FIG. 3 is a diagram showing an example of a configuration of 5GS functional blocks in the communication system of FIG. 2. FIG. 1 shows an example of control information exchanged in 5GS. FIG. 4 is a diagram showing a configuration example in which the devices shown in FIGS. 2 and 3 are applied to a time synchronization network assuming communication between terminal devices. FIG. 1 shows an example of a frame format when using a direct communication function between mobile stations that are terminal devices in 5GS. A diagram showing an example of resource allocation when using the relay function FIG. 1 is a first diagram showing an example of a change in transmission timing of an SL in a communication system according to a first embodiment; FIG. 2 is a second diagram showing an example of a change in transmission timing of SL in the communication system according to the first embodiment; A flowchart showing an operation of a relay mobile station according to the first embodiment for notifying information on a delay time FIG. 1 is a diagram showing an example of the configuration of a processing circuit that realizes a communication system according to a first embodiment when the processing circuit is realized by a processor and a memory; FIG. 1 is a diagram showing an example of a processing circuit for implementing a communication system according to a first embodiment, the processing circuit being configured with dedicated hardware; FIG. 1 shows a state in which a communication system according to a second embodiment is applied. FIG. 6 is a diagram showing a portion of the network shown in FIG. 5 that corresponds to a communication system according to a second embodiment. FIG. 11 is a diagram showing an example of information transmission timing between a master mobile station and a remote mobile station in a communication system according to a second embodiment. FIG. 1 shows a configuration example of a communication system according to a second embodiment. FIG. 13 is a diagram for explaining a use case of a communication system according to a third embodiment.

Below, the communication system, base station, mobile station, control circuit, storage medium and communication method relating to the embodiments of the present disclosure are described in detail with reference to the drawings.

Embodiment 1.
1 is a diagram showing an example of a configuration of a communication system 20 according to embodiment 1. The communication system 20 includes a network control device 10, a core device 11, a base station 12, a relay mobile station 13, and a remote mobile station 14.

The network control device 10 manages time synchronization networks such as the TSC network and the TSN network. The network control device 10 generally exists as a server on the time synchronization network, but does not necessarily have to exist in the wired TSC network on the base station 12 side, and may be in the wired TSC network under a specific mobile station. The network control device 10 is sometimes called a CNC (Centralized Network Controller). The core device 11 is a device that provides the network function of the mobile communication system. The mobile communication system is, for example, 5GS, but is not limited to this. The mobile communication system may be an existing system or may not be an existing system. In the following, an example will be described in which the mobile communication system is 5GS. The base station 12 controls communication between the core device 11 and a relay mobile station 13 with which direct communication is possible. Note that in the example of FIG. 1, there is only one relay mobile station 13, but the communication system 20 can be equipped with multiple relay mobile stations 13, and the base station 12 can communicate with multiple relay mobile stations 13. The relay mobile station 13 is a mobile station that communicates directly with the base station 12. The remote mobile station 14 is a mobile station that communicates with the base station 12 via the relay mobile station 13.

In the communication system 20, the relay mobile station 13 and the remote mobile station 14 have different roles depending on factors such as their positional relationship with the base station 12, but may have the same configuration as devices. In the following description, when there is no need to distinguish between the relay mobile station 13 and the remote mobile station 14, they may simply be referred to as mobile stations. That is, the communication system 20 includes two or more mobile stations that can communicate directly or indirectly with the base station 12. Among the mobile stations, those that can communicate directly with the base station 12 are referred to as relay mobile stations 13, and those that can communicate with the base station 12 via the relay mobile station 13 are referred to as remote mobile stations 14.

Before explaining the configuration of each part, we will explain the general configuration and operation of a communication system that performs time-synchronized communication. Figure 2 is a diagram showing an example of a communication system that performs time-synchronized communication using 5GS. Figure 3 is a diagram showing an example of the configuration of 5GS functional blocks in the communication system of Figure 2. Figure 2 is the diagram shown in Figure 5.27.1-1 of 3GPP TS 23.501 V17.2.0 (2021-09). Figure 3 is the diagram shown in Figure 4.4.8.2-1 of 3GPP TS 23.501 V17.2.0 (2021-09) with the addition of a network control device equivalent to the network control device 10 in Figure 1.

In FIG. 2, 5GS provides time synchronization services by connecting synchronously operating end stations together with the external network, which is a wired network. From the end station's perspective, 5GS operates as a TSN bridge and provides functions corresponding to the time synchronization protocol. The time synchronization protocol is, for example, PTP (Precision Time Protocol), represented by IEEE (Institute of Electrical and Electronics Engineers) 1588 and IEEE 802.1AS. NW-TT (Network side Tsn Translator) and DS-TT (Device side Tsn Translator) are placed at the entrance and exit of 5GS and perform functions corresponding to PTP, such as time stamp processing. In the configuration shown in FIG. 2, the external network and 5GS each operate based on their own master clock, so corrections are also made to the clock discrepancy between the two.

In FIG. 3, user data on the U-plane is sent to the (R)AN (Radio) Access Network (R-AN), which corresponds to a base station, via the UPF (User Plane Function) in the core device, and is then transmitted to the UE (User Equipment), which is a terminal device, via a wireless line. The UPF includes the NW-TT. The (R)AN corresponds to the gNB in FIG. 2. The U-plane is transmitted to the TSN End Station on the UE side after the synchronization process is performed by the DS-TT connected to the UE. To achieve time-synchronized communication, complex control is required, such as stabilizing the delay time, ensuring periodicity, and securing transmission capacity. The delay time also includes the residence time in the 5GS or individual devices. The same applies hereafter. The external network is provided with a network control device that controls the time-synchronized communication, and the network control device exchanges various control information with the C-plane, which is the control layer of the 5GS. The various types of control information include information such as an information packet transmission period, capacity, arrival timing to 5GS, and traffic pattern from each end station belonging to the range controlled by the network control device. The range controlled by the network control device is also called a domain.

The TSN-AF (Time Sensitive Network-Application Function) or NEF (Network Exposure Function) shown in Figure 3 interfaces with the network control device, accumulates necessary information, and notifies each 5GS function. The SMF (Session Management Function) and PCF (Policy Control Function) monitor the clock offset between the external network and 5GS and perform processing to correct the deviation. Figure 5.27.2-1 of 3GPP TS23.501 V17.2.0 (2021-09) specifies TSCAI (Time Sensitive Communication Assistance Information) shown in Figure 4 as information for controlling TSC packets. Figure 4 is a diagram showing an example of control information exchanged in 5GS. The control information includes the transmission direction of each session, which is a path for transmitting information between the UE and the UPF, the transmission period, the arrival timing of the packet, and the survival time, which is information corresponding to the margin time until the control is stopped at the end station. A part of the information of the TSCAI is passed from the AMF (Access and Mobility Management Function) to the (R)AN and the UE, and is used for scheduling of wireless transmission. An example of using the information of the TSCAI for scheduling of the (R)AN is also disclosed in paragraph 0058 of the above-mentioned Patent Document 1.

In such a configuration, the network control device of the external network needs to know the delay time of each part in order to realize time-synchronized communication between end stations. The virtual TSN bridge supported by 5GS is also expected to have a constant delay time. However, 5GS accommodates multiple UEs and provides communication services with various QoS (Quality of Service). For this reason, even if there is time-related information provided by TSCAI, information transmission cannot necessarily be realized with a constant delay time due to scheduling. As an example, the NW-TT and DS-TT can implement output buffers and absorb delay fluctuations between the (R)AN and the UE with the output buffer. As mentioned above, the (R)AN can know the traffic pattern based on the advance information of TSCAI and schedule to reduce delay fluctuations, so if a small delay time margin is secured, it is possible to constant the residence time of 5GS, i.e., the delay time, in the output buffer.

Figures 2 and 3 show examples of implementing TSC services by utilizing wireless communication between (R)AN and UE, but with the advancement of wireless communication technology, various network configurations can now be constructed. Figure 5 shows an example of a configuration in which the devices shown in Figures 2 and 3 are applied to a time synchronization network assuming communication between terminal devices. In Figure 5, the 5GS core device, the base station which is a gNB or (R)AN, and the NW-TT are expressed as a single configuration as core device/base station/NW-TT, and the mobile station which is a UE in Figures 2 and 3 and the DS-TT are expressed as a single configuration as mobile station/DS-TT. In addition, the End station shown in Figure 2 is abbreviated as ES. In the network shown in Figure 5, communication between terminal devices is communication between mobile stations. In the network shown in FIG. 5, a wireless TSC network between mobile stations is established by mobile stations directly connected to a base station, a wired TSC network on the network side is established connected to the base station, and a wired TSC network on the mobile station side is established by ESs connected to mobile stations, relay mobile stations, or remote mobile stations.

In the examples of Figures 2 and 3, the TSC network was constructed using the wireless interfaces of the base station and the mobile station. For mobile stations directly connected to the base station, the base station schedules the transmission timing, so a certain degree of consistency in delay time can be expected. On the other hand, as shown in the lower right part of Figure 5, a local wireless TSC network between mobile stations can be constructed by utilizing the direct communication function between mobile stations. For the mobile stations that make up such a local network, there are various mobile stations in various situations, such as a mobile station that can transmit user data to the base station, a mobile station that is connected only to the control channel, and a mobile station that is completely outside the coverage of the base station inside a metal box. In such a case, when a remote mobile station that cannot transmit user data to the base station cooperates with a network-side wired TSC network under the base station, a mobile station that can transmit user data to the base station is used as a relay mobile station to realize time-synchronized communication between the TSC networks.

As mentioned above, the direct communication function between UEs, i.e. mobile stations, corresponds to the function called SL in 3GPP. Figure 6 is a diagram showing an example of a frame format when using the direct communication function between mobile stations, which are terminal devices, in 5GS. When used in conjunction with base station-mobile station communication, a portion of the UL (UpLink) resources is allocated to the SL. The resources that can be allocated to the SL are an area specified by a time and frequency range called the SL Resource Pool. This area can be arranged quite discretely in terms of time.

The resource allocation in SL is not necessarily instructed by the scheduler of the base station, but each mobile station selects resources in an autonomous and distributed manner while observing the resource usage status of surrounding mobile stations. Figure 7 is a diagram showing an example of resource allocation when the relay function is used. In Figure 7, an example is shown in which the frame length of one frame is 10 ms and the slot length is 0.5 ms. The resources allocated to DL (DownLink) between the base station and the relay mobile station are shown as circles, and the resources allocated to SL between the relay mobile station and the remote mobile station are shown as squares. As mentioned above, the scheduler of the base station allocates DL resources based on TSCAI so that the delay fluctuation is small. On the other hand, the resources used in SL are selected autonomously by the mobile station, so the delay amount may change significantly depending on the communication status of the surrounding mobile stations.

In addition, the 3GPP standard requires that resources used in SL be reselected at a fixed time. Figure 7 shows an example in which a delay time Td ₁ is required for the transmission of a certain packet, and the allocation position of SL changes with resource reselection, shortening the delay time to Td ₂ for the transmission of the next packet. From the perspective of the entire network, this results in a discrete change in the delay time in 5GS, i.e., the delay time in the TSN virtual bridge, which has a significant impact on time-synchronized communication services. It is possible to calculate the worst value of the delay time and provide a buffer that allows the TSN translator to hold a data signal for a long time, but the amount of variation in the delay time increases compared to communication between a base station and a mobile station, which significantly deteriorates the efficiency of the network.

Therefore, in this embodiment, we describe a communication system 20 that efficiently performs time-synchronized communication even when the delay time in 5GS varies due to SL communication.

Returning to the explanation of the individual devices shown in Figure 1, the relay mobile station 13 shown in Figure 1 corresponds to the relay mobile station shown in Figure 5, and the remote mobile station 14 shown in Figure 1 corresponds to the remote mobile station shown in Figure 5. The communication system 20 shown in Figure 1 is a communication system that constitutes part of the time synchronization network shown in Figure 5.

The core device 11 comprises a time synchronization unit 111 and a network function unit 112. The time synchronization unit 111 is a TSC-AF, TSN-AF, etc. that provides 5GS TSC services in the core device 11, and performs time synchronization services. The network function unit 112 includes a NEF (Network Exposure Function), TSCTSF (Time Sensitive Communication and Time Synchronization Function), etc. that provide an interface with outside 5GS that provides network functions in the core device 11.

The base station 12 includes a base station control unit 121 and a base station radio unit 122. The base station control unit 121 provides functions such as MAC (Media Access Control) and scheduler functions in the base station 12. The base station control unit 121 allocates resources for communication with the relay mobile station 13, which is a mobile station with which direct communication is possible, and notifies the network control device 10 of time information of the allocated resources as delay time information. The base station radio unit 122 includes high-frequency elements such as analog units and radio signal processing units in the base station 12, and provides wireless communication functions. The base station radio unit 122 communicates with the relay mobile station 13, which is a mobile station with which direct communication is possible.

The relay mobile station 13 includes a time synchronization unit 131, a mobile station control unit 132, and a mobile station radio unit 133. The time synchronization unit 131 is a TSC-AF, TSN-AF, etc. that provides 5GS TSC services in the relay mobile station 13, and performs time synchronization services. The mobile station control unit 132 provides resource reservation, MAC functions, etc. in the relay mobile station 13. The mobile station control unit 132 allocates resources for SL communication with the remote mobile station 14, which is another mobile station, and notifies the network control device 10 of time information of the allocated resources as delay time information. The mobile station radio unit 133 includes high-frequency elements such as analog units, radio signal processing units, etc. in the relay mobile station 13, and provides wireless communication functions. The mobile station radio unit 133 communicates with the remote mobile station 14, which is another mobile station, and communicates with the base station 12 with which direct communication is possible.

The remote mobile station 14 includes a time synchronization unit 141, a mobile station control unit 142, and a mobile station radio unit 143. The time synchronization unit 141 is a TSC-AF, TSN-AF, etc. that provides 5GS TSC services in the remote mobile station 14, and performs time synchronization services. The mobile station control unit 142 provides resource reservation, MAC functions, etc. in the remote mobile station 14. The mobile station control unit 142 allocates resources for SL communication with the relay mobile station 13, which is another mobile station, and notifies the network control device 10 of time information among the allocated resources as delay time information. The mobile station radio unit 143 includes high-frequency elements such as analog units, radio signal processing units, etc. in the remote mobile station 14, and provides wireless communication functions. The mobile station radio unit 143 communicates with the relay mobile station 13, which is another mobile station.

The operation of the communication system 20 will be described. In the first embodiment, the communication system 20 is assumed to have a configuration in which the remote mobile station 14 corresponding to the remote mobile station shown in FIG. 5 is included in the domain via the relay mobile station 13 corresponding to the relay mobile station shown in FIG. 5. The network control device 10 grasps the characteristics of each part of the time synchronization network including the virtual TSN bridge carried by 5GS, sets the delay time and transmission capacity of each part, and performs band allocation and transmission timing instructions for the end stations belonging to the domain under control. That is, the network control device 10 performs resource allocation and instructs transmission timing to devices other than the device that notified the delay time information. Devices other than the device that notified the delay time information may include the base station 12, relay mobile station 13, remote mobile station 14, etc. shown in FIG. 1, as well as the NW-TT, DS-TT, ES, etc. shown in FIG. 5. In this way, the network control device 10 uses the delay time information notified from the base station 12, etc. to manage the time synchronization network.

The time synchronization unit 111 of the core device 11 performs various settings and information collection for operating the 5GS as a TSN bridge. The time synchronization unit 111 provides various parameters as a TSN bridge to the network control device 10, receives setting parameters and time synchronization traffic information from the network control device 10, and performs 5GS settings including NW-TT, DS-TT, etc. via the network function unit 112. The various parameters include, for example, expected delay time, transmission capacity, QoS, etc., and the time synchronization traffic information includes, for example, arrival timing, transmission period, QoS, etc. The network function unit 112 of the core device 11 performs various settings, notifications, session management, TSC stream management, etc. within the 5GS based on the information from the time synchronization unit 111, and collects information within the 5GS and discloses it to the time synchronization unit 111, the network control device 10, etc. Note that the range of various settings and management in the network control device 10 and the core device 11 is wide, so they are not specified here. For details, see the aforementioned 3GPP TS23.501 V17.2.0 (2021-09), as well as 3GPP TS23.502 V17.2.1 (2021-09), 3GPP TS23.503 V17.2.0 (2021-09), etc.

In the base station 12, the base station control unit 121 and the base station radio unit 122 perform scheduling, resource allocation, etc. based on instructions from the core device 11, and transmit information with the relay mobile station 13.

The time synchronization unit 131 of the relay mobile station 13 cooperates with the time synchronization unit 111 of the core device 11 to realize a time-synchronized communication service within 5GS. The time synchronization unit 131 also provides various information to the mobile station control unit 132, and determines setting parameters and collects information. The mobile station control unit 132 controls information transmission in DL and UL between the base station 12 and the relay mobile station 13, and also secures resources for SL and controls transmission. The mobile station radio unit 133 performs radio transmission based on instructions from the mobile station control unit 132.

The time synchronization unit 141 of the remote mobile station 14 cooperates with the time synchronization unit 111 of the core device 11 to realize a time-synchronized communication service within 5GS. The time synchronization unit 141 also provides various information to the mobile station control unit 142, and performs operations such as determining setting parameters and collecting information. The mobile station control unit 142 controls information transmission in the SL between the relay mobile station 13 and the remote mobile station 14, and also secures resources for the SL and performs transmission control. The mobile station radio unit 143 performs radio transmission based on instructions from the mobile station control unit 142.

Time-synchronized communication is generally used for periodic control, so for example, the traffic pattern is such that information is sent every 10 ms. In response to this, 5GS implements a function called SPS (Semi Persistent Scheduling) that periodically secures transmission resources. This is, for example, as shown in FIG. 7, to constantly secure transmission resources within a frame. As a result, 5GS can achieve stable time-synchronized communication with a certain degree of stability in delay time. Here, in the case of information transmission in the downlink direction from the base station 12 to the remote mobile station 14, in distributed resource allocation, the mobile station control unit 132 of the relay mobile station 13 is responsible for SL resource allocation. Distributed resource allocation is, for example, resource allocation Mode 2 described in Chapter 6.3.2 of 3GPP TR37.985 V16.0.0 (2020-06). For various reasons such as fluctuations in the surrounding radio wave environment, the allocation position of the SL resource on the time axis may be changed in the mobile station control unit 132. At this time, the mobile station control unit 132 notifies the network control device 10 of the change in the 5GS delay time or the change in the residence time in the 5GS. As a method of notifying the network control device 10 from the mobile station control unit 132, various methods such as the following can be considered.

1. The mobile station control unit 132 notifies the relative time difference with respect to the SL resource allocation position on the conventional time axis. The relative time difference is, for example, time or the number of slots. Specifically, the 5GS delay time increases or decreases by XX milliseconds, which corresponds to Td ₁ -Td ₂ in FIG. 7.
2. The mobile station control unit 132 notifies the slot number of the newly secured resource. For example, the mobile station control unit 132 notifies an absolute number or a relative slot position from the beginning of the frame.
3. The mobile station control unit 132 reports slot position information within the resource pool.

Finally, the change in delay time is notified to the network control device 10, but generally, this is transmitted via the network function unit 112 of the core device 11. That is, information on the change in delay time is transmitted from the mobile station control unit 132 of the relay mobile station 13 to the network function unit 112 of the core device 11 via the base station 12, and the network function unit 112 notifies the network control device 10 on the external network of the change in delay time. Based on the information on the change in delay time, the network control device 10 updates the delay time information of the corresponding TSN bridge, and performs reconfiguration of the time synchronization network, parameter adjustment, etc.

A specific example of notification of delay time fluctuation is shown. FIG. 8 is a first diagram showing an example of change in SL transmission timing in the communication system 20 according to the first embodiment. In SPS, a transmission period P _rsvp , which is a resource allocation period for SL, is specified. Once the mobile station control unit 132 allocates SL resources, the mobile station control unit 132 secures SL resources for a certain period of time at each transmission period P _rsvp . When performing resource reselection, the mobile station control unit 132 searches for resources with as little delay time fluctuation as possible, but there is a possibility that the desired resource cannot be obtained, especially when the traffic volume is high. In the example of FIG. 8, an example is shown in which a resource that is ΔT ₁ behind is selected at the time of resource reselection. After this, the mobile station control unit 132 allocates resources at a P _rsvp period until the next resource reselection. As a result, the 5GS delay time after resource reselection is longer by ΔT ₁ than the 5GS delay time at time T ₀ . The mobile station control unit 132 notifies the network control device 10, the network function unit 112 of the core device 11, and the like of information corresponding to the discrete amount of change _ΔT1 in the intra-5GS delay time. The unit of the information corresponding to the amount of change _ΔT1 is not particularly limited as long as it represents time, such as the number of slots or milliseconds.

FIG. 9 is a second diagram showing an example of a change in the transmission timing of the SL in the communication system 20 according to the first embodiment. FIG. 9 shows the change in resource allocation from a different perspective than FIG. 8. All base stations 12 are synchronized with the time of the Global Positioning System (GPS) and have a common frame start timing. In 3GPP, the frame length is specified as 10 ms. On the other hand, the slot length varies depending on the subcarrier width. FIG. 9 shows an example of a slot length = 0.5 ms, in which case, one frame is composed of 20 slots. The position of the SL resource shown by the black square in FIG. 9 can also be expressed by the slot number from the frame start. In particular, when the transmission period _Prsvp of the SPS is an integer multiple of the frame length or an integer fraction of the frame length, the same slot number is assigned as the slot of the SL. When a slot with a timing different from that of the previous slot number is assigned at the time of resource reselection, the mobile station control unit 132 notifies time information corresponding to the delay difference _ΔT2 . The unit of the time information is not particularly limited to the number of slots, time, etc. In the case of FIG. 9, the mobile station control unit 132 can also notify the slot number of the allocated slot instead of notifying the difference information.

Note that, although we have explained here the allocation of SL resources by the mobile station control unit 132 of the relay mobile station 13, a similar phenomenon will occur with respect to the DL and UL resources that the base station control unit 121 of the base station 12 allocates as SPS in the DL and UL.

In time-synchronized communication in the uplink direction from the remote mobile station 14 to the base station 12, the allocation of SL resources is handled by the mobile station control unit 142 of the remote mobile station 14. As in the case of the downlink direction, when the allocation position of the SL resources is changed in the uplink direction, the 5GS delay time changes discretely. In this case, the mobile station control unit 142 of the remote mobile station 14 notifies the network control device 10 or the network function unit 112 of the core device 11 of similar information such as the change in the 5GS delay time. The delay time information may be notified from the mobile station control unit 142 of the remote mobile station 14 via the time synchronization unit 141 of the remote mobile station 14, the time synchronization unit 131 of the relay mobile station 13, etc.

In addition, in the configuration shown in FIG. 5, when all mobile stations, that is, all mobile stations in this embodiment, can communicate with the base station 12 and a control channel is directly established between the base station 12 and the mobile stations, the resource allocation Mode 1 described in Chapter 6.3.2 of 3GPP TR37.985 V16.0.0 (2020-06) in which the base station 12 allocates SL resources can be used. In this case, the base station control unit 121 of the base station 12 allocates SL resources between the relay mobile station 13 and the remote mobile station 14 in addition to the DL and UL resource allocation between the base station 12 and the relay mobile station 13. In this case, the base station control unit 121 of the base station 12 notifies the network control device 10 or the network function unit 112 of the core device 11 of information similar to that in the case of Mode 1, such as changes in delay time associated with changes in DL and UL resource allocation, and changes in delay time associated with changes in SL resource allocation.

The operation of the base station 12, the relay mobile station 13, and the remote mobile station 14 in the first embodiment to notify the delay time information will be described using a flowchart. Here, the relay mobile station 13 will be described as an example, but the base station 12 and the remote mobile station 14 operate in the same manner. FIG. 10 is a flowchart showing the operation of the relay mobile station 13 in the first embodiment to notify the delay time information. In the relay mobile station 13, when the mobile station control unit 132 performs resource allocation or resource reallocation for communication with the base station 12 or the remote mobile station 14 (step S1: Yes), the mobile station control unit 132 notifies the network control device 10 of the delay time information (step S2). The specific notification method from the mobile station control unit 132 to the network control device 10 is as described above. When the mobile station control unit 132 does not perform resource allocation or resource reallocation for communication with the base station 12 or the remote mobile station 14 (step S1: No), the mobile station control unit 132 ends the operation of the flowchart shown in FIG. 10. Note that the mobile station control unit 132 periodically performs the operation of the flowchart shown in FIG. 10.

In this way, when the base station control unit 121 of the base station 12, the mobile station control unit 132 of the relay mobile station 13, and the mobile station control unit 142 of the remote mobile station 14 allocate resources in communication with other devices, they notify the network control device 10 of the information on the time of the allocated resources as delay time information. Also, when the mobile station control unit 132 of the relay mobile station 13 reselects resources for SL communication with the remote mobile station 14, it notifies the network control device 10 of information indicating the time or slot from the frame start position, or information on the time or slot that is the difference from the previous resource position, as delay time information. Also, when the mobile station control unit 142 of the remote mobile station 14 reselects resources for SL communication with the relay mobile station 13, it notifies the network control device 10 of information indicating the time or slot from the frame start position, or information on the time or slot that is the difference from the previous resource position, as delay time information. Note that the mobile station control unit 132 of the relay mobile station 13 may notify the network control device 10 of the delay time information via the time synchronization unit 131. Furthermore, the mobile station control unit 142 of the remote mobile station 14 may notify the network control device 10 of information on the delay time via the time synchronization unit 141 .

In addition, when there are multiple mobile stations and all of the mobile stations can communicate directly with the base station 12, the base station control unit 121 of the base station 12 notifies the network control device 10 of information indicating the time or slot from the frame start position, or information on the time or slot that is the difference from the previous resource position, as delay time information for resources allocated for SL communication between the mobile stations and for reselected resources. In addition, the base station control unit 121 of the base station 12 notifies the network control device 10 of information indicating the time or slot from the frame start position, or information on the time or slot that is the difference from the previous resource position, as delay time information for resources allocated for DL and UL communication with the mobile stations and for reselected resources.

In addition, the base station control unit 121 of the base station 12, the mobile station control unit 132 of the relay mobile station 13, and the mobile station control unit 142 of the remote mobile station 14 may notify the network control device 10 of the delay time information via the network function unit 112, which is a network function possessed by the core device 11, or may notify the network control device 10 via the time synchronization unit 111, which is an application that provides a time synchronization service possessed by the core device 11.

Next, the hardware configuration of each device of the communication system 20 will be described. In the base station 12, the base station radio unit 122 is a radio interface capable of radio communication with the relay mobile station 13 and the like. The base station control unit 121 is realized by a processing circuit. In the relay mobile station 13, the mobile station radio unit 133 is a radio interface capable of radio communication with the base station 12, the remote mobile station 14 and the like. The time synchronization unit 131 and the mobile station control unit 132 are realized by a processing circuit. In the remote mobile station 14, the mobile station radio unit 143 is a radio interface capable of radio communication with the relay mobile station 13 and the like. The time synchronization unit 141 and the mobile station control unit 142 are realized by a processing circuit. In the core device 11, the time synchronization unit 111 and the network function unit 112 are realized by a processing circuit. The processing circuit may be a processor and memory that executes a program stored in a memory, or may be dedicated hardware. The processing circuit is also called a control circuit.

11 is a diagram showing an example of the configuration of a processing circuit 90 in the case where the processing circuit for realizing the communication system 20 according to the first embodiment is realized by a processor 91 and a memory 92. The processing circuit 90 shown in FIG. 11 is a control circuit and includes a processor 91 and a memory 92. When the processing circuit 90 is configured with the processor 91 and the memory 92, each function of the processing circuit 90 is realized by software, firmware, or a combination of software and firmware. The software or firmware is described as a program and stored in the memory 92. In the processing circuit 90, each function is realized by the processor 91 reading and executing the program stored in the memory 92. That is, the processing circuit 90 includes a memory 92 for storing a program that will result in the processing of the communication system 20 being executed. This program can also be said to be a program for causing the communication system 20 to execute each function realized by the processing circuit 90. This program may be provided by a storage medium in which the program is stored, or may be provided by other means such as a communication medium.

The above program can also be said to be a program executed by the communication system 20 to perform the following steps when a base station 12 that controls communication between a relay mobile station 13, which is a mobile station with which direct communication is possible, and a core device 11 that provides a network function of the mobile communication system, or two or more mobile stations that are capable of communicating directly or indirectly with the base station 12, allocate resources in communication with other devices: a first step of notifying the network control device 10 of time information of the allocated resources as delay time information; and a second step in which the network control device 10 uses the delay time information to control the time synchronization network.

Here, the processor 91 is, for example, a CPU (Central Processing Unit), a processing device, an arithmetic device, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor). The memory 92 is, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), an EEPROM (Electrically EPROM), or other non-volatile or volatile semiconductor memory, a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc).

Figure 12 is a diagram showing an example of a processing circuit 93 in the case where the processing circuit for realizing the communication system 20 according to the first embodiment is configured with dedicated hardware. The processing circuit 93 shown in Figure 12 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination of these. The processing circuit may be partially realized with dedicated hardware and partially realized with software or firmware. In this way, the processing circuit can realize each of the above-mentioned functions by dedicated hardware, software, firmware, or a combination of these.

As described above, according to this embodiment, in the communication system 20, the mobile station control unit 132 of the relay mobile station 13, the mobile station control unit 142 of the remote mobile station 14, the base station control unit 121 of the base station 12, and the like notify the network control device 10 of resource information when they allocate or reallocate resources. The network control device 10, which manages the time synchronization network, can quickly grasp the fluctuations in the discrete delay time of 5GS by notifications from the mobile station control unit 132 of the relay mobile station 13, the mobile station control unit 142 of the remote mobile station 14, the base station control unit 121 of the base station 12, and the like. This allows the communication system 20 to efficiently perform time-synchronized communication even when the delay time in the 5GS mobile communication system fluctuates. In addition, since the communication system 20 can flexibly change the configuration of the time synchronization network, it is possible to reduce the amount of buffering provided by the TSN translator, and to achieve a substantial reduction in delay time.

Embodiment 2.
In the second embodiment, a case will be described in which a local time synchronization network is required even in a situation where the coverage of the base station 12 is not available.

Figure 13 is a diagram showing how the communication system 20a according to the second embodiment is applied. Figure 13 shows an example of an application according to the second embodiment, which is an example in which a local time synchronization network is required even in a situation where there is no coverage of the base station 12. For example, an application in which multiple AGVs work together to carry one piece of luggage is considered. In this use case, information such as speed, direction, acceleration and deceleration needs to be shared in real time between the AGVs, and a local network is used. The wired TSC network of each AGV is connected via a mobile station and a DS-TT. In the local network, one of the mobile stations becomes a master station and manages the network. Figure 14 is a diagram showing a part of the network shown in Figure 5 that corresponds to the communication system 20a according to the second embodiment. In this way, the communication system 20a according to the second embodiment corresponds to a local time synchronization network.

Figure 15 is a diagram showing an example of information transmission timing between the master mobile station 16 and the remote mobile station 14-1 in the communication system 20a according to embodiment 2. The resource allocation position of the remote mobile station 14-1 varies with respect to the periodic reference seen from the master mobile station 16, so that the 5GS delay time in the uplink direction from the remote mobile station 14-1 to the master mobile station 16 varies discretely.

Figure 16 is a diagram showing an example of the configuration of a communication system 20a relating to embodiment 2. The communication system 20a includes a network control device 15, a master mobile station 16, and a remote mobile station 14. Note that while there is one remote mobile station 14 in Figure 16, in reality, the communication system 20a can include multiple remote mobile stations 14 as shown in Figure 13. The remote mobile stations 14-1 to 14-3 shown in Figure 13 have the same configuration as the remote mobile station 14 shown in Figure 16. The communication system 20a shown in Figure 16 is a communication system that constitutes part of a time synchronization network, similar to the communication system 20 of embodiment 1.

The network control device 15 manages time synchronization networks such as the TSC network and the TSN network, as well as local time synchronization networks. The network control device 15 is usually considered to be outside the mobile stations such as the master mobile station 16 and the remote mobile station 14, but may be installed inside the mobile stations such as the master mobile station 16 and the remote mobile station 14. As with the network control device 10 of embodiment 1, the network control device 15 may assign resources and instruct transmission timing to devices other than the device that notified the delay time information.

The master mobile station 16 includes a time synchronization unit 161, a mobile station control unit 162, and a mobile station radio unit 163. The time synchronization unit 161 is a TSC-AF, TSN-AF, etc. that provides 5GS TSC services in the master mobile station 16, and performs time synchronization services. The time synchronization unit 161 cooperates with the time synchronization unit 141 of the remote mobile station 14 to provide a time-synchronized communication service using 5GS SL. The mobile station control unit 162 provides resource reservation, MAC functions, etc. in the master mobile station 16. The mobile station control unit 162 allocates resources for SL communication with the remote mobile station 14, which is another mobile station, and notifies the network control device 15 of information about the time of the allocated resources as delay time information. The mobile station radio unit 163 includes high-frequency elements such as analog units, radio signal processing units, etc. in the master mobile station 16, and provides wireless communication functions. The mobile station radio unit 163 communicates with a remote mobile station 14 which is another mobile station.

In the remote mobile station 14, the time synchronization unit 141 cooperates with the time synchronization unit 161 of the master mobile station 16 to provide a time-synchronized communication service using 5GS SL.

In the following description, when there is no need to distinguish between the master mobile station 16 and the remote mobile station 14, they may simply be referred to as mobile stations. In other words, the communication system 20a includes two or more mobile stations capable of operating in cooperation with other mobile stations.

In all of the SL communication from the master mobile station 16 to the remote mobile station 14, the SL communication from the remote mobile station 14 to the master mobile station 16, and the SL communication from a remote mobile station 14 to another remote mobile station 14, the mobile station control unit 142 or the mobile station control unit 162 on the transmitting side performs SL resource allocation. When a resource selection that causes a fluctuation in the 5GS delay time is performed in the SL resource reallocation, the mobile station control unit 142 or the mobile station control unit 162 notifies the network control device 15 of the change in delay time similar to that in the first embodiment. In this case, the mobile station control unit 162 may notify the network control device 15 directly, or may notify the network control device 15 via the time synchronization unit 161. The mobile station control unit 142 may notify the network control device 15 directly, or may notify the network control device 15 via the time synchronization unit 141 and the time synchronization unit 161.

In this way, when the mobile station control unit 162 of the master mobile station 16 and the mobile station control unit 142 of the remote mobile station 14 allocate resources for SL communication with other mobile stations, they notify the network control device 15 of the information on the time of the allocated resources as delay time information. Also, when the mobile station control unit 162 of the master mobile station 16 and the mobile station control unit 142 of the remote mobile station 14 reselect resources for SL communication, they notify the network control device 15 of information indicating the time or slot from the frame start position, or information on the time or slot that is the difference from the previous resource position, as delay time information. Note that the mobile station control unit 162 of the master mobile station 16 may notify the network control device 15 of the delay time information via the time synchronization unit 161. Also, the mobile station control unit 142 of the remote mobile station 14 may notify the network control device 15 of the delay time information via the time synchronization unit 141.

As described above, according to this embodiment, in the communication system 20a, the mobile station control unit 162 of the master mobile station 16, the mobile station control unit 142 of the remote mobile station 14, and the like notify the network control device 15 of resource information when they allocate or reallocate resources. The network control device 15, which manages the time synchronization network, can quickly grasp the discrete delay time fluctuations of 5GS by notifications from the mobile station control unit 162 of the master mobile station 16, the mobile station control unit 142 of the remote mobile station 14, and the like. This allows the communication system 20a to efficiently perform time-synchronized communication even when the delay time in the 5GS mobile communication system fluctuates. In addition, since the communication system 20a can flexibly change the configuration of the time synchronization network, it is possible to reduce the amount of buffering provided by the TSN translator, and to achieve a substantial reduction in delay time.

Embodiment 3.
In the third embodiment, a case will be described in which in the communication system 20, the relay mobile station 13 and the remote mobile station 14 move and the relay mobile station 13 performs handover to change the base station 12 to which it is connected.

Figure 17 is a diagram for explaining a use case of the communication system 20 according to the third embodiment. In Figure 17, the base stations 12-1 and 12-2 are the base stations 12 shown in Figure 1, and the remote mobile stations 14-1 to 14-3 are the remote mobile stations 14 shown in Figure 1. When a hierarchical time synchronization network corresponding to Figure 5 is operated under the base station 12-1, for example, when a local time synchronization network such as the linked AGV application described in the second embodiment moves, the mobile station radio unit 133 of the relay mobile station 13 continues the operation of a similar time synchronization network under the base station 12-2 by handing over. The resource pool available in SL is set in the UL resource as described in Figure 6, but the position on the time and frequency may differ depending on the base station 12. In addition, even if the resource pool setting is the same, it is expected that the communication situation around the base station 12 will change significantly, and it is assumed that the position on the time axis of the SL allocation resource will fluctuate. Since the base stations 12-1 and 12-2 are synchronized by using GPS as a reference, the frame start position is unchanged even if a handover occurs. Although the base station control unit 121 of the base station 12-2 secures DL and UL resources that have as little delay time fluctuation as possible as SPS based on the TSCAI information, there is a high possibility that delay time fluctuation will occur in the DL and UL resources as well.

Therefore, in this embodiment, when a handover occurs, the base station control unit 121 or the mobile station control units 132 and 142 notify the network control device 10 of information on the variation in delay time. The base station control unit 121 may notify the network control device 10 of the information on the variation in delay time directly, or may notify the network control device 10 via the network function unit 112 of the core device 11. The mobile station control unit 132 may notify the network control device 10 of the information on the variation in delay time directly, or may notify the network control device 10 via the network function unit 112 of the core device 11.

In this way, when there are multiple base stations 12 and at least one mobile station changes the base station 12 to which it is connected by handover, the base station control unit 121 of the base station 12, the mobile station control unit 132 of the relay mobile station 13, and the mobile station control unit 142 of the remote mobile station 14 notify the network control device 10 of delay time information.

As described above, according to this embodiment, in the communication system 20, the mobile station control unit 132 of the relay mobile station 13, the mobile station control unit 142 of the remote mobile station 14, the base station control unit 121 of the base station 12, and the like notify the network control device 10 of resource information when they allocate or reallocate resources. The network control device 10, which manages the time synchronization network, can quickly grasp the fluctuation of the discrete delay time of 5GS by notifications from the mobile station control unit 132 of the relay mobile station 13, the mobile station control unit 142 of the remote mobile station 14, the base station control unit 121 of the base station 12, and the like. As a result, the communication system 20 can efficiently perform time-synchronized communication even if a handover occurs due to the movement of the relay mobile station 13 and the remote mobile station 14, and the delay time in the 5GS mobile communication system fluctuates. In addition, since the communication system 20 can flexibly change the configuration of the time synchronization network, the amount of buffer provided in the TSN translator can be reduced, and a substantial reduction in delay time can be achieved.

The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or the embodiments may be combined with each other. Also, parts of the configurations may be omitted or modified without departing from the spirit of the invention.

10, 15 Network control device, 11 Core device, 12, 12-1, 12-2 Base station, 13 Relay mobile station, 14, 14-1 to 14-3 Remote mobile station, 16 Master mobile station, 20, 20a Communication system, 111, 131, 141, 161 Time synchronization unit, 112 Network function unit, 121 Base station control unit, 122 Base station radio unit, 132, 142, 162 Mobile station control unit, 133, 143, 163 Mobile station radio unit.

Claims (27)

A communication system constituting a part of a time synchronization network,
A network control device that controls the time synchronization network;
A core device that provides a network function of a mobile communication system;
A base station that controls communication between a relay mobile station that can directly communicate with the core device and the relay mobile station;
the relay mobile station being a mobile station capable of directly communicating with the base station;
a remote mobile station that is a mobile station capable of indirectly communicating with the base station via the relay mobile station;
Equipped with
when the base station allocates resources in communication with the relay mobile station , notifies the network control device of information on time of the allocated resources as information on a delay time;
when the relay mobile station allocates resources in communication with the remote mobile station, notifies the network control device of information on time of the allocated resources as information on a delay time;
When the remote mobile station allocates resources in communication with the relay mobile station, the remote mobile station notifies the network control device of information on time of the allocated resources as information on a delay time.
A communication system comprising: The network control device includes:
when the base station allocates the resources and receives a notification of the delay time from the base station, instructs the relay mobile station and the remote mobile station on transmission timing ;
when the relay mobile station has performed the resource allocation and has received a notification of the delay time from the relay mobile station, instructing the base station and the remote mobile station on a transmission timing;
when the remote mobile station performs the resource allocation and receives a notification of the delay time from the remote mobile station, instructs the base station and the relay mobile station of a transmission timing.
2. The communication system according to claim 1 . When the relay mobile station reselects the resource for side link communication with the remote mobile station, the relay mobile station notifies, as the information on the delay time, information indicating a time or slot from a frame start position, or information on a time or slot that is a difference from a previous resource position.
3. The communication system according to claim 1 or 2. When the remote mobile station reselects the resource for side link communication with the relay mobile station, the remote mobile station notifies, as the information on the delay time, information indicating a time or slot from a frame start position, or information on a time or slot that is a difference from a previous resource position.
3. The communication system according to claim 1 or 2. the base station notifies, as the delay time information for the resources allocated for downlink and uplink communication with the mobile station and for the reselected resources, information indicating a time or slot from a frame start position, or information on a time or slot that is a difference from a previous resource position;
5. A communication system according to claim 1, wherein the communication system comprises: The base station and the mobile station notify the network control device of the information on the delay time via a network function of the core device.
6. A communication system according to claim 1 , wherein the communication system comprises: The base station and the mobile station notify the network control device of the information on the delay time via an application that provides a time synchronization service included in the core device.
6. A communication system according to claim 1 , wherein the communication system comprises: When there are a plurality of base stations and at least one of the mobile stations changes the base station to which it is connected by handover,
The base station and the mobile station notify the network control device of information on the delay time.
8. A communication system according to claim 1, wherein the communication system comprises: A communication system constituting a part of a time synchronization network,
A network control device that controls the time synchronization network;
Two or more mobile stations capable of operating in cooperation with other mobile stations;
Equipped with
Among the two or more mobile stations, one mobile station becomes a master mobile station and the remaining mobile stations become remote mobile stations;
when the master mobile station allocates resources for communication of a side link with the remote mobile station, the master mobile station directly notifies the network control device of information on time of the allocated resources as information on a delay time;
When the remote mobile station allocates resources for side link communication between the master mobile station or another remote mobile station, the remote mobile station notifies the network control device directly or via the master mobile station of information about the time of the allocated resources as delay time information.
A communication system comprising: the network control device assigns the resources and instructs a transmission timing to a mobile station other than the mobile station that has notified the network control device of the information on the delay time.
10. The communication system according to claim 9 . When the mobile station reselects the resource for the side link communication, the mobile station notifies, as the information on the delay time, information indicating a time or slot from a frame start position, or information on a time or slot that is a difference from a previous resource position.
11. The communication system according to claim 9 or 10 . The mobile station,
a time synchronization unit that performs a time synchronization service;
a mobile station control unit that notifies the network control device of information about the delay time via the time synchronization unit;
12. A communication system according to claim 9 , further comprising: A base station included in a communication system constituting a part of a time synchronization network,
The communication system includes a network control device that controls the time synchronization network, a core device that provides a network function of a mobile communication system, and two or more mobile stations that can directly or indirectly communicate with the base station;
The base station,
a base station radio unit for communicating with the mobile station with which direct communication is possible;
a base station control unit that allocates resources in communication with the mobile station that can directly communicate with the base station and notifies the network control device of information regarding time of the allocated resources as information on a delay time;
A base station comprising: There are a plurality of mobile stations, and all of the mobile stations can directly communicate with the base station;
The base station control unit notifies, as the information on the delay time, information indicating a time or slot from a frame start position, or information on a time or slot that is a difference from a previous resource position, for the resources allocated for side link communication between the mobile stations and the reselected resources.
14. The base station according to claim 13 . the base station control unit notifies, as the delay time information, information indicating a time or slot from a frame start position, or information of a time or slot that is a difference from a previous resource position, for the resources allocated for downlink and uplink communication with the mobile station and the reselected resources;
15. A base station according to claim 13 or 14 . The base station control unit notifies the network control device of the delay time information via a network function of the core device.
16. A base station according to any one of claims 13 to 15 . The base station control unit notifies the network control device of the delay time information via an application that provides a time synchronization service included in the core device.
16. A base station according to any one of claims 13 to 15 . When there are a plurality of base stations and at least one of the mobile stations changes the base station to which it is connected by handover,
The base station control unit notifies the network control device of information about the delay time.
18. A base station according to any one of claims 13 to 17 . Two or more mobile stations are included in a communication system that constitutes a part of a time synchronization network,
The communication system includes:
A network control device that controls the time synchronization network;
A core device that provides a network function of a mobile communication system;
A base station that controls communication between a relay mobile station that can directly communicate with the mobile stations and the core device;
Including,
Among the mobile stations, a mobile station capable of communicating directly with the base station is defined as a relay mobile station, and a mobile station capable of communicating with the base station via the relay mobile station is defined as a remote mobile station;
The relay mobile station,
a time synchronization unit for performing a time-synchronized communication service;
a mobile station radio unit that communicates with the remote mobile station and communicates with the base station ;
a mobile station control unit that allocates resources for communication of a side link with the remote mobile station and notifies the network control device via the core device of information about time of the allocated resources as delay time information;
Equipped with
The remote mobile station:
a time synchronization unit for performing a time-synchronized communication service;
a mobile station radio unit for communicating with the relay mobile station;
a mobile station control unit that allocates resources for communication of a side link with the relay mobile station and notifies the network control device via the core device of information about time of the allocated resources as delay time information;
A mobile station comprising: In the relay mobile station, when the mobile station control unit reselects the resource for the side link communication with the remote mobile station, the mobile station control unit notifies, as the information of the delay time, information indicating a time or slot from a frame start position, or information of a time or slot that is a difference from a previous resource position.
20. A mobile station according to claim 19 . In the remote mobile station, when the mobile station control unit reselects the resource for side link communication with the relay mobile station, the mobile station control unit notifies, as the information on the delay time, information indicating a time or slot from a frame start position, or information on a time or slot that is a difference from a previous resource position.
20. A mobile station according to claim 19 . the mobile station control unit of the relay mobile station and the mobile station control unit of the remote mobile station notify the network control device of information on the delay time via a network function of the core device;
A mobile station according to any one of claims 19 to 21 . the mobile station control unit of the relay mobile station and the mobile station control unit of the remote mobile station notify the network control device of information about the delay time via an application that provides a time synchronization service and that is included in the core device;
A mobile station according to any one of claims 19 to 21 . When there are a plurality of base stations and at least one of the mobile stations changes the base station to which it is connected by handover,
The mobile station control unit notifies the network control device of information about the delay time.
A mobile station according to any one of claims 19 to 23 . Two or more mobile stations are included in a communication system that constitutes a part of a time synchronization network,
The communication system includes a network control device that controls the time synchronization network,
Among the two or more mobile stations, one mobile station becomes a master mobile station and the remaining mobile stations become remote mobile stations;
The master mobile station,
a time synchronization unit for performing a time-synchronized communication service;
a mobile station radio unit for communicating with the remote mobile station;
a mobile station control unit that allocates resources for communication of a side link with the remote mobile station and notifies the network control device of information regarding time of the allocated resources as delay time information directly or via the time synchronization unit ;
Equipped with
The remote mobile station:
a time synchronization unit for performing a time-synchronized communication service;
a mobile station radio unit for communicating with the master mobile station or other remote mobile stations;
a mobile station control unit that allocates resources for side link communication between the master mobile station or the other remote mobile station, and notifies the network control device of information on time of the allocated resources as delay time information directly or via a time synchronization unit of the remote mobile station and a time synchronization unit of the master mobile station;
A mobile station comprising: When reselecting the resource for the side link communication, the mobile station control unit of the master mobile station and the mobile station control unit of the remote mobile station notify, as the information on the delay time, information indicating a time or slot from a frame start position, or information on a time or slot that is a difference from a previous resource position.
26. A mobile station according to claim 25 . A communication method for a communication system constituting a part of a time synchronization network, comprising:
The communication system includes:
A network control device that controls the time synchronization network;
A core device that provides a network function of a mobile communication system;
A base station that controls communication between a relay mobile station that can directly communicate with the core device and the relay mobile station;
the relay mobile station being a mobile station capable of directly communicating with the base station;
a remote mobile station that is a mobile station capable of indirectly communicating with the base station via the relay mobile station;
Equipped with
When the base station allocates resources in communication with the relay mobile station, the base station notifies the network control device via the core device of information about time of the allocated resources as delay time information;
When the relay mobile station allocates resources in communication with the remote mobile station , the relay mobile station notifies the network control device via the core device of information about time of the allocated resources as information about a delay time;
a first step of notifying the network control device via the core device of information on time of the allocated resources as information on delay time when the remote mobile station allocates resources in communication with the remote mobile station;
a second step of the network control device controlling the time synchronization network using information on the delay time;
A communication method comprising:

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