Wireless communication system, wireless communication method, clustering management device, and program

Abstract

A wireless communication system according to the present disclosure includes a central station, base stations, and terminal stations configured so as to be capable of performing wireless communication among the terminal stations. The terminal stations transmit, to a base station, information concerning the radio quality and information concerning services being used. The base station performs clustering of the terminal stations according to clustering control information received from the central station. In addition, the base station transmits, to the central station, the information received from the terminal stations and information concerning the radio environment of the terminal stations. The central station learns, on the basis of the information received from the base station, clustering that meets the required radio quality depending on the services being used at the terminal stations and transmits, to the base station, information concerning the learned clustering as the clustering control information.

Description

Technical Field

[0001] The present disclosure relates to clustering of user equipment (UE clustering) that enables communication between user equipment, and particularly to a technique for performing UE clustering that optimizes the radio quality of user equipment.

Background Art

[0002] Non-Patent Documents 1 and 2 disclose the management of radio quality in 5G NR. The radio quality to be managed is QoE (Quality of Experience). In 5G NR, a configuration for measuring QoE is transmitted from a base station (NG-RAN Node) to a user equipment (UE). The user equipment measures QoE based on the configuration and transmits the measurement result to the base station as a QoE report. The base station transmits the QoE report to a radio quality server (QoE server). In this way, the radio quality of each user equipment is managed.

[0003] By the way, in recent years, for various purposes such as improving radio quality in a network and equalizing network usage, UE clustering that clusters user equipment capable of communication between user equipment has been considered. UE clustering changes the radio quality of user equipment. However, in the prior art disclosed in Non-Patent Documents 1 and 2, the change in radio communication quality due to UE clustering is not considered.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

[0005] This disclosure has been made in view of the issues described above. The purpose of this disclosure is to ensure the required wireless quality by optimizing the clustering of terminal stations. [Means for solving the problem]

[0006] This disclosure provides a wireless communication system to achieve the above objective. The wireless communication system of this disclosure comprises a central station, base stations that communicate with the central station, and terminal stations that communicate wirelessly with the base stations. The terminal stations are configured to enable wireless communication between terminal stations. The terminal stations are also configured to transmit information about wireless quality and information about the service being used to the base stations. The base stations are configured to perform clustering of terminal stations (UE clustering) according to clustering control information received from the central station. The base stations are also configured to transmit information received from terminal stations and information about the wireless environment of terminal stations to the central station. Based on the information received from the base stations, the central station is configured to learn a clustering that satisfies the required wireless quality according to the service being used at the terminal stations, and to transmit information about the learned clustering to the base stations as clustering control information.

[0007] Furthermore, in order to achieve the above objective, this disclosure provides a wireless communication method using a terminal station configured to enable wireless communication between terminal stations. The wireless communication method of this disclosure includes the following steps: The first step is to transmit information regarding radio quality and information regarding the service being used from the terminal station to a base station that communicates wirelessly with the terminal station. The second step is to transmit the information transmitted from the terminal station to the base station and information regarding the radio environment of the terminal station from the base station to a central station that communicates with the base station. The third step is to learn a clustering (UE clustering) that satisfies the required radio quality according to the service being used at the terminal station, based on the information transmitted from the base station to the central station. The fourth step is to transmit the learned clustering information from the central station to the base station as clustering control information. The fifth step is to perform clustering of the terminal station according to the clustering control information transmitted from the central station to the base station.

[0008] Furthermore, in order to achieve the above objective, this disclosure provides a clustering management device for managing clustering of terminal stations (UE clustering) configured to enable wireless inter-terminal station communication. The clustering management device of this disclosure comprises one or more processors and a program memory coupled to one or more processors and storing a plurality of executable instructions. The plurality of instructions are configured to cause the one or more processors to perform the following processes: The first process is to obtain information regarding the wireless quality of the terminal station, information regarding the services being used by the terminal station, and information regarding the wireless environment of the terminal station from a base station that communicates wirelessly with the terminal station. The second process is to learn a clustering that satisfies the required wireless quality according to the services being used by the terminal station, based on the information obtained from the base station. The third process is to transmit the learned clustering information to the base station.

[0009] Furthermore, this disclosure provides a program to achieve the above objectives. The program of this disclosure is configured to cause a computer to perform the following processes: The first process is to obtain information about the wireless quality of the terminal station, information about the services being used by the terminal station, and information about the wireless environment of the terminal station from a base station that communicates wirelessly with the terminal station. The second process is to learn a clustering (UE clustering) that satisfies the required wireless quality according to the services being used at the terminal station, based on the information obtained from the base station. The third process is to transmit the learned clustering information to the base station. The program of this disclosure may be recorded on a computer-readable recording medium or may be provided over a network. [Effects of the Invention]

[0010] According to the technology disclosed herein, a clustering (UE clustering) is learned at the terminal station that satisfies the required wireless quality according to the service being used, based on information regarding the wireless quality of the terminal station, information regarding the service being used by the terminal station, and information regarding the wireless environment of the terminal station. This makes it possible to ensure the required wireless quality by optimizing the clustering of the terminal station. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows the configuration of a wireless communication system according to an embodiment of this disclosure. [Figure 2] This is a functional block diagram showing the functions of a wireless communication system according to an embodiment of the present disclosure. [Figure 3] This figure shows an example of the hardware configuration of a centralized station used as a clustering management device. [Figure 4] This is a flowchart showing the flow of information between a central station and a base station, and between a base station and a terminal station, in a wireless communication system according to an embodiment of this disclosure. [Figure 5] This flowchart shows a process that is repeatedly performed in a wireless communication system according to an embodiment of this disclosure. [Modes for carrying out the invention]

[0012] 1. Configuration of the wireless communication system The wireless communication system according to the embodiment of this disclosure is a system that provides users with a variety of communication services, including Web, voice calls, and video distribution. The configuration of the wireless communication system according to the embodiment of this disclosure is shown in Figure 1. As shown in Figure 1, the wireless communication system 10 includes a plurality of terminal stations 40, a plurality of base stations 30, and a central station 20. The terminal stations 40 are also referred to as UEs (User Equipment). The base stations 30 are also referred to as nodes or access points.

[0013] Terminal station 40 is a mobile radio station. Terminal station 40 is a MIMO-compatible terminal station. Furthermore, terminal station 40 is a terminal station that can form a cluster through wireless terminal-to-terminal (D2D) communication. Terminal station 40 supports various communication services provided by the wireless communication system 10. Users who possess terminal station 40 can use the desired communication services using terminal station 40. A typical example of terminal station 40 is a smartphone.

[0014] Base station 30 is a radio station with a fixed location. Base station 30 communicates with terminal station 40 wirelessly. Base station 30 includes, for example, a base station 30A for small cells that has a phased array antenna and emits a directional beam BM, and a base station 30B for macrocells that forms a wide coverage area A by emitting radio waves in all directions. Base station 30 may also be configured with a centralized antenna or a distributed antenna.

[0015] The centralized station 20 is a device that is arranged on the network and communicates with each base station 30 via the network. The centralized station 20 may be, for example, a cloud server or a dedicated server. Alternatively, the centralized station 20 may be integrated into any one of the base stations 30. The centralized station 20 is configured as a clustering management device that manages the clustering (UE clustering) of the terminal stations 40. The centralized station 20 transmits clustering control information for allocating the terminal stations 40 to clusters to each base station 30. In the example shown in FIG. 1, the cluster CL1 is formed by the terminal stations 40 communicating with the base station 30A, and the clusters CL2 and CL3 are formed by the terminal stations 40 communicating with the base station 30B.

[0016] 2. Functions of the wireless communication system FIG. 2 is a functional block diagram showing the functions of the wireless communication system 10. Hereinafter, the functions of each of the terminal station 40, the base station 30, and the centralized station 20 that constitute the wireless communication system 10 will be described.

[0017] The terminal station 40 includes an antenna 400, a received signal radio conversion unit 401, an analog-digital conversion unit 402, a data signal demodulation and decoding unit 403, and an information bit detection unit 404. The radio signal transmitted from the base station 30 is received by the antenna 400. The radio signal transmitted from the base station 30 includes a cluster assignment for UE clustering.

[0018] The radio signal received by the antenna 400 is converted by the received signal radio conversion unit 401 into an analog received signal in the baseband band. The analog received signal obtained by the received signal radio conversion unit 401 is digitized by the analog-digital conversion unit 402 for digital demodulation. The digitized received data signal from the analog received signal is demodulated by the data signal demodulation and decoding unit 403, and further error correction decoding is performed. The information bits obtained by the demodulation and error correction decoding of the received data signal are detected by the information bit detection unit 404.

[0019] The terminal station 40 further includes a terminal station information notification unit 405. The terminal station information notification unit 405 generates a signal for notifying the current radio quality and the service in use of the terminal station 40. The generated signal is transmitted from the antenna 400 to the base station 30. The radio quality is the user's perceived quality (QoE), and a typical one is the delay time. When UE clustering is performed, the radio quality including the delay time changes depending on the current clustering situation of the terminal station 40. On the other hand, the notification of the service in use includes the quality required by the service provider (required QoE quality). If the current radio quality of the terminal station 40 does not meet the required QoE quality, it can be said that there is room for improvement in the cluster assignment of the terminal station 40.

[0020] The base station 30 includes an antenna 300, a received signal radio conversion unit 301, an analog-digital conversion unit 302, a data signal demodulation and decoding unit 303, and an information bit detection unit 304. The radio signal transmitted from the terminal station 40 is received by the antenna 300. The radio signal transmitted from the terminal station 40 includes radio quality information and service-in-use information.

[0021] The radio signal in the RF band received by the antenna 300 is converted into an analog received signal in the baseband band by the received signal radio conversion unit 301. The analog received signal obtained by the received signal radio conversion unit 301 is digitized by the analog-digital conversion unit 302 for digital demodulation. The received data signal digitized from the analog received signal is demodulated by the data signal demodulation and decoding unit 303, and further error correction decoding is performed. Information bits are obtained by the demodulation and error correction decoding of the received data signal. The information bits are detected by the information bit detection unit 304 and transmitted to the concentration station 20. The information bits transmitted to the concentration station 20 include the radio quality information and service-in-use information of the terminal station 40.

[0022] Furthermore, the base station 30 includes an information bit generation unit 305, a data signal modulation coding unit 306, a digital-to-analog conversion unit 307, and a transmission signal wireless conversion unit 308. The signal transmitted from the central station 20 to the base station 30 is input to the information bit generation unit 305. The signal input to the information bit generation unit 305 includes clustering control information for UE clustering.

[0023] The information bit generation unit 305 generates information bits from the clustering control information for the data to be transmitted to the terminal station 40 and the result of the selection of the optimal base station. The data to be transmitted to the terminal station 40 includes the optimized cluster assignment. The information bits generated from the clustering control information are subjected to error correction coding by the data signal modulation coding unit 306 and then digitally modulated. The digitally modulated transmission signal is converted to analog by the digital-to-analog conversion unit 307. The analogized transmission signal is converted from a baseband signal to an RF band radio signal by the transmission signal radio conversion unit 308 and transmitted from the antenna 300 to the terminal station 40.

[0024] Furthermore, the base station 30 includes a received power intensity detection unit 309, an obstacle detection unit 310, and a surrounding environment detection unit 311. The received power intensity detection unit 309 detects the received power intensity (RSSI) from the received signal transmitted from the terminal station 40 and received by the antenna 300, and notifies the central station 20 of the detected received power intensity. The obstacle detection unit 310 detects obstacles such as buildings and trees that may affect communication with the terminal station 40, and notifies the central station 20 of the detected obstacles. The surrounding environment detection unit 311 detects the surrounding environment, such as terrain, that may affect communication with the terminal station 40, and notifies the central station 20 of the detected surrounding environment.

[0025] Received power strength, obstacles, and the surrounding environment are information regarding the wireless environment of terminal station 40. Not only the clustering status, but also the wireless environment of terminal station 40 is a factor that affects the wireless quality of terminal station 40. In addition, as wireless environment information of terminal station 40, reference signal received power (RSRP), reference signal received quality (RSRQ), signal-to-interference noise ratio (SINR), etc. may be detected instead of, or in conjunction with, received power strength.

[0026] The central station 20 includes a terminal station information collection unit 201, a received power strength collection unit 202, an obstacle information collection unit 203, and a surrounding environment information collection unit 204. The terminal station information collection unit 201 collects radio quality information and service information in use for each terminal station 40 notified by the base station 30. The received power strength collection unit 202 collects received power strength information for each terminal station 40 notified by the base station 30. The obstacle information collection unit 203 collects obstacle information notified by the base station 30. The surrounding environment information collection unit 204 collects surrounding environment information notified by the base station 30.

[0027] The central station 20, which is a clustering management device, includes a clustering learning optimization processing unit 205 and a clustering control unit 206. The clustering learning optimization processing unit 205 learns UE clustering to optimize the radio quality of each terminal station 40 from the collected information. Specifically, based on received power strength information, obstacle information, and surrounding environment information representing the radio environment of each terminal station 40, clustering of each terminal station 40 is performed to reduce the difference between the current radio quality of each terminal station 40 and the required QoE quality of the service being used by each terminal station 40. The learned clustering information is notified to the base station 30 as clustering control information by the clustering control unit 206.

[0028] 3. Hardware configuration of the central office Here, the hardware configuration of the central station 20 as a clustering management device will be described. Figure 3 shows an example of the hardware configuration of the central station 20. The central station 20 shown in Figure 3 is a computer equipped with a communication interface 21, one or more processors (hereinafter simply referred to as processors) 22, program memory 23, and information memory 25. The program memory 23 stores multiple executable instructions 24 that constitute the program. The information memory 25 stores various information such as clustering control information 26 and required QoE quality information 27 for each service. The communication interface 21, program memory 23, and information memory 25 are communicateably coupled to the processor 22.

[0029] The central station 20 is connected to the network via a communication interface 21. Radio quality information, service information in use, and radio environment information notified from the base station 30 are received via the communication interface 21. Clustering control information generated at the central station 20 is also transmitted to the base station 30 via the communication interface 21.

[0030] The processor 22 may be a central processing unit (CPU), a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), or another processing unit. Alternatively, the processor 22 may be a combination of two or more CPUs, FPGAs, ASICs, or other processing units. When the instruction 24 stored in the program memory 23 is executed, the processor 22, which is a CPU, FPGA, ASIC, or another processing unit, is triggered to perform its function as a clustering management device. The program memory 23 may be a separate device from the processor 22, or it may be built into the processor 22.

[0031] At least one of the multiple instructions 24 is programmed to cause the processor 22 to collect radio quality information, service information in use, and radio environment information from the base station 30 for each terminal station 40. At least one of the multiple instructions 24 is programmed to cause the processor 22 to learn a clustering arrangement based on the information collected from the base station, such that the required QoE quality according to the service in use is met at each terminal station 40. At least one of the multiple instructions 24 is programmed to cause the processor 22 to transmit information about the learned clustering (clustering control information) to the base station 30.

[0032] 4. Information flow in wireless communication systems The flow of information in the wireless communication system 10 can be summarized as shown in Figure 4. Figure 4 is a flowchart showing the flow of information between the central station 20 and the base station 30, and between the base station 30 and the terminal station 40. The flow of information shown in this flowchart is also the flow of information realized by the wireless communication method according to this embodiment. In the flowchart, a first terminal station 40-1 and a second terminal station 40-2 are shown as terminal stations 40 that communicate wirelessly with the base station 30. The first terminal station 40-1 and the second terminal station 40-2 may belong to the same cluster, or they may belong to different clusters.

[0033] According to the flowchart shown in Figure 4, in step S101, radio quality information and service information in use are transmitted from the first terminal station 40-1 to the base station 30. In step S102, the radio environment information of the first terminal station 40-1 is transmitted from the base station 30 to the central station 20 along with the radio quality information and service information in use received from the first terminal station 40-1.

[0034] In step S103, the second terminal station 40-2 transmits radio quality information and service information in use to the base station 30. In step S104, the base station 30 transmits the radio environment information of the second terminal station 40-2, along with the radio quality information and service information in use received from the second terminal station 40-2, to the central station 20.

[0035] The timing at which base station 30 receives information from the first terminal station 40-1 and the second terminal station 40-2 may be pre-scheduled or may be left to chance. Furthermore, base station 30 may transmit information regarding the first terminal station 40-1 and information regarding the second terminal station 40-2 to the central station 20 separately at different times, or it may transmit all of this information together to the central station 20 at the same time.

[0036] The central station 20 further collects radio quality information, service information in use, and radio environment information for several terminal stations 40 other than the first terminal station 40-1 and the second terminal station 40-2. In step S105, the central station 20 learns a clustering from each collected piece of information that optimizes the radio quality of each terminal station 40, including the first terminal station 40-1 and the second terminal station 40-2. Optimization of radio quality means that each terminal station 40 satisfies the required QoE quality of the service in use. In step S106, clustering control information is transmitted from the central station 20 to the base station 30 to instruct the base station 30 on the learned clustering.

[0037] In step S107, the base station 30 instructs the first terminal station 40-1 to assign a cluster according to the clustering control information. In step S108, the base station 30 instructs the second terminal station 40-2 to assign a cluster according to the clustering control information. The base station 30 may transmit the cluster assignment instruction to the first terminal station 40-1 and the cluster assignment instruction to the second terminal station 40-2 separately at different timings, or it may transmit both instructions at the same time.

[0038] In cluster assignment, the first terminal station 40-1 and the second terminal station 40-2 may be assigned to the same cluster, or they may be assigned to different clusters. Furthermore, they may be assigned to a cluster of another base station 30 whose coverage areas overlap, for example. By appropriately changing cluster assignments among all terminal stations 40 in this way, the required QoE quality for the services being used at each terminal station 40 is ensured.

[0039] 5. Processing performed by the wireless communication system The services used at each terminal station 40 change over time. The wireless environment at each terminal station 40 also changes over time. Therefore, the wireless communication system 10 repeatedly performs clustering learning to optimize the wireless quality at each terminal station 40. Figure 5 is a flowchart showing the process that is repeatedly performed by the wireless communication system 10.

[0040] In step S201, the required QoE quality is determined from the services currently in use at each terminal station 40.

[0041] In step S202, at each terminal station 40, the packet error rate is calculated from the propagation loss, fading environment, and allocated power to each user stream in the current clustering situation. The packet error rate is calculated using a predefined formula or map with propagation loss, fading environment, and allocated power as parameters.

[0042] In step S203, the delay time is calculated for each terminal station 40 from the currently used transmission method, the packet error rate calculated in step S202, and the average retransmission time. The transmission methods used include, for example, CDMA (Code Division Multiple Access), WCDMA (Wideband CDMA) (registered trademark), FDMA (Frequency Division Multiple Access), TDMA (Time Division Multiple Access), OFDM (Orthogonal Frequency Division Multiplexing), and OFDMA (Orthogonal Frequency Division Multiple Access). The delay time is calculated using a predefined formula or map with the transmission method, packet error rate, and average retransmission time as parameters. The delay time represents the radio quality (QoE quality) of the terminal station 40 based on the current clustering method.

[0043] In step S204, the base station 30 notifies the central station 20 of the wireless environment of each terminal station 40, the wireless quality based on the current clustering method, and the services in use and their required QoE quality. If there are multiple base stations 30 communicating with the central station 20, all base stations 30 notify the central station 20 of the wireless environment, wireless quality, and the services in use and their required QoE quality of each terminal station 40.

[0044] In step S205, it is determined whether the required QoE quality is satisfied at each terminal station 40. If the required QoE quality is not satisfied, the process proceeds to step S206. The conditions for the determination in step S205 to be positive may be, for example, that the required QoE quality is satisfied at all terminal stations 40, or that the required QoE quality is satisfied at a certain percentage of terminal stations 40.

[0045] In step S206, the clustering method is changed. Specifically, the cluster assignment to each terminal station 40 is updated based on the wireless environment of each terminal station 40 so that the difference between the wireless quality of each terminal station 40 and the required QoE quality is eliminated.

[0046] After the clustering method is changed, steps S202 to S205 are executed again. Then, steps S202 to S206 are repeatedly executed until the required QoE quality is satisfied at each terminal station 40, and the clustering method is changed to optimize the radio quality. In other words, a clustering that optimizes the radio quality at each terminal station 40 is learned.

[0047] If the required QoE quality is satisfied in step S206, the series of processes ends. The processes shown in the flowchart of Figure 5 may be executed periodically or irregularly. As an example of irregular execution, steps S201 to S205 may be executed when there is a change in the service being used at any of the terminal stations 40. [Explanation of Symbols]

[0048] 10 Wireless communication systems 20 Central station 30 base station 40 Terminal Stations

Claims

1. Centralized station and, A base station that communicates with the aforementioned centralized station, The system comprises a terminal station configured to enable wireless inter-terminal station communication, which communicates wirelessly with the aforementioned base station, The aforementioned terminal station is It is configured to transmit information regarding wireless quality and information regarding the service being used to the base station, The aforementioned base station is The clustering of the terminal stations is performed according to the clustering control information received from the central station. To acquire information regarding the wireless environment of the terminal station, including at least one of the following: information regarding the strength of the received power of the signal received from the terminal station, information regarding obstacles affecting communication with the terminal station, and information regarding the surrounding environment affecting communication with the terminal station. The system is configured to transmit to the central station information regarding the radio quality and the services currently in use, as well as information regarding the radio environment, received from the terminal station. The aforementioned centralized station is Based on the information received from the base station, the terminal station learns a clustering that satisfies the required radio quality according to the service being used, The system is configured to transmit learned clustering information as clustering control information to the base station. A wireless communication system characterized by the following features.

2. In the wireless communication system according to claim 1, The aforementioned terminal station is The packet error rate is calculated from the propagation loss in the current clustering status of the terminal station, the fading environment of the terminal station, and the power allocated to the user stream of the terminal station. The delay time is calculated from the transmission method currently used by the terminal station, the packet error rate, and the average retransmission time. The system is configured to transmit the aforementioned delay time as information regarding the wireless quality. A wireless communication system characterized by the following features.

3. A wireless communication method in a wireless communication system comprising a central station, a base station that communicates with the central station, and a terminal station that communicates wirelessly with the base station, The aforementioned terminal station is configured to enable wireless communication between terminal stations, Transmitting information regarding wireless quality and information regarding the service being used from the terminal station to the base station, The base station acquires at least one of the following as information regarding the wireless environment of the terminal station: information regarding the strength of the received power of the signal received from the terminal station, information regarding obstacles affecting communication with the terminal station, and information regarding the surrounding environment affecting communication with the terminal station. The base station transmits the information regarding the radio quality and the information regarding the service in use, which have been transmitted from the terminal station to the base station, and the information regarding the radio environment acquired by the base station, from the base station to the central station. Based on the information transmitted from the base station to the central station, the terminal station learns a clustering that satisfies the required radio quality according to the service being used, The learned clustering information is transmitted from the central station to the base station as clustering control information, This includes performing clustering of the terminal stations in accordance with the clustering control information transmitted from the central station to the base station. A wireless communication method characterized by the following:

4. In the wireless communication method described in Claim 3, Transmitting the aforementioned information regarding wireless quality from the terminal station to the base station is: The packet error rate is calculated from the propagation loss in the current clustering status of the terminal station, the fading environment of the terminal station, and the power allocated to the user stream of the terminal station. The delay time is calculated from the transmission method currently used by the terminal station, the packet error rate, and the average retransmission time. This includes transmitting the aforementioned delay time as information regarding the wireless quality. A wireless communication method characterized by the following:

5. A clustering management device for managing the clustering of terminal stations configured to enable wireless communication between terminal stations, One or more processors, The system comprises a program memory that is coupled with one or more processors and stores multiple executable instructions, The aforementioned plurality of instructions are provided to the one or more processors: The following are obtained from a base station that communicates wirelessly with the terminal station: information regarding the wireless quality of the terminal station, information regarding the services being used by the terminal station, and information regarding the wireless environment of the terminal station. Based on the information obtained from the base station, the terminal station learns a clustering that satisfies the required radio quality according to the service being used, The system is configured to transmit learned clustering information to the base station and to perform the following actions. A clustering management device characterized by the following features.

6. The following information is obtained from a base station that communicates wirelessly with the terminal station: information regarding the wireless quality of a terminal station configured to enable wireless communication between terminal stations, information regarding the services being used by the terminal station, and information regarding the wireless environment of the terminal station. Based on the information obtained from the base station, the terminal station learns a clustering that satisfies the required radio quality according to the service being used, The system is configured to transmit learned clustering information to the base station and to cause a computer to perform the following actions. A program characterized by the following features.

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