Information processing device, method, and program

Abstract

The present invention improves the efficiency of reporting, by UE, information related to the propagation characteristics to a network. This information processing device executes: acquiring, on the basis of first information related to the loss of a signal transmitted cooperatively from one or a plurality of transmission / reception points (TRPs) to user equipment (UE) and second information according to requirements of an application, a first allowable range of the loss of the signal in the UE; and determining, on the basis of the first allowable range, the resolution, applied to the UE, of information related to the propagation characteristics between the UE and the one or the plurality of TRPs, the information being reported from the UE to a network.

Description

Information processing device, method, and program

[0001] This disclosure relates to wireless communication.

[0002] In wireless communications such as 5th Generation Mobile Communication Systems (5G), distributed MIMO (Multi-Input Multi-Output) has been proposed, which involves selecting one or more distributed stations near a mobile station from among multiple distributed stations distributed within the communication area of ​​a single base station to communicate with. According to distributed MIMO, by appropriately combining radio waves transmitted simultaneously from multiple distributed stations, the received signal power at the mobile station can be improved and throughput can be increased.

[0003] In coordinated transmission between multiple distributed base stations (mTRPs, hereinafter referred to as distributed stations), such as in distributed MIMO, the technique of improving received signal power by ensuring that the transmitted signals from each distributed station are received in phase at the User Equipment (UE) is called Coherent Joint Transmission (CJT). For example, in coordinated transmission by N distributed stations, assuming that the transmitted power of each distributed station is equal, theoretically, with CJT, the received signal power at the UE will be N squared times the received signal power of a signal from a single distributed station. By improving the received signal power through CJT, throughput can be improved and latency can be reduced.

[0004] When there is a phase offset in the carrier waves between multiple distributed stations performing coordinated transmission, a loss of received signal power occurs when the received signals are combined at the UE. This loss of received signal power is the difference between the theoretical value of the received signal power obtained by the CJT and the actual received signal. To compensate for the carrier wave phase offset of each distributed station, the UE measures the phase offset value for each distributed station and reports it to each station.

[0005] Regarding the resolution of the phase offset of UE, the phase offset Φ in the subband σ of distributed station n ｎ，σIt is disclosed that, for a resolution MΦ, it can take one of the following values: {0, 2π / (MΦ-1), 4π / (MΦ-1), ..., (MΦ-2)2π / (MΦ-1), "invalid"} (for example, Non-Patent Document 1). It is disclosed that the resolution MΦ of the phase offset is determined by the network and notified to each UE.

[0006] Qualcomm Incorporated, CSI enhancements for >32 ports and UE-assisted CJT, 3GPP TSG RAN WG1 #117, R1-2405149, May 24, 2024, pp.17

[0007] One aspect of this disclosure aims to provide an information processing device, method, and program that can improve the efficiency of reporting information on propagation characteristics by UEs.

[0008] One aspect of the present disclosure is an information processing device comprising: a control unit that performs: first information relating to the loss of a signal coordinately transmitted from one or more transmission / reception points (TRPs) to a user device (UE), and second information depending on the requirements of an application; and determining the resolution of information relating to the propagation characteristics between the one or more TRPs and the UE, which is applied to the UE and reported from the UE to the network, based on the first tolerance range.

[0009] Another aspect of the present disclosure is a method by which a computer performs the following: first information relating to the loss of a signal coordinately transmitted from one or more transmission / reception points (TRPs) to a user device (UE), and second information depending on the requirements of an application, to obtain a first acceptable range of the signal loss in the UE; and, based on the first acceptable range, to determine the resolution of information relating to the propagation characteristics between the one or more TRPs and the UE, which is applied to the UE and reported from the UE to the network.

[0010] Another aspect of the present disclosure is a program for causing a computer to perform the following: first information relating to the loss of signals coordinately transmitted from one or more transmission / reception points (TRPs) to a user device (UE), and second information depending on the requirements of an application; and based on the first tolerance, determining the resolution of information relating to the propagation characteristics between the one or more TRPs and the UE, which is applied to the UE and reported from the UE to the network.

[0011] According to one aspect of this disclosure, an information processing device, method, and program can be provided that can improve the efficiency of reporting information on propagation characteristics by UEs.

[0012] Figure 1 is a diagram showing an example of the system configuration of a communication system according to the first embodiment. Figure 2 is an example of the CJT sequence in the communication system according to the first embodiment. Figure 3 is a diagram illustrating the hardware configuration of the control device. Figure 4 is a diagram showing an example of the functional configuration of the control device. Figure 5 is an example of an MCS index table. Figure 6 is a graph showing an example of loss margin-resolution correspondence information. Figure 7 is an example of a flowchart of the resolution MΦ determination process according to the first embodiment. Figure 8 is an example of the CJT sequence in a communication system according to modification 1 of the first embodiment. Figure 9 is an example of a flowchart of the MCS index update process according to modification 2 of the first embodiment. Figure 10 is an example of a flowchart of the resolution MΦ determination process according to the second embodiment. Figure 11 is an example of a flowchart of the resolution MΦ determination process according to modification 1 of the second embodiment. Figure 12 is an example of the CJT sequence in a communication system according to the third embodiment. Figure 13 is a diagram showing an example of the hardware configuration of the UE. Figure 14 is a diagram showing an example of the functional configuration of the UE.

[0013] While a high resolution for the phase offset allows for precise adjustment, it increases the number of bits required to represent a single phase offset, thus increasing the data size reported by the UE to the network. When the measurement interval is relatively longer than the frequency fluctuation, resulting in low frequency stability, and when high gain is not required, there is no need to increase the resolution of the phase offset. Lowering the resolution can reduce the data size reported to the network.

[0014] The resolution of the phase offset is affected by gain and deviation. Gain and deviation influence each other with signal loss and the acceptable range of signal loss. For example, when high gain is required, it is necessary to keep signal loss low. For example, when communication quality stability is required, that is, when deviation must be kept low, it is necessary to keep signal loss low or have a wide acceptable range of signal loss. In one aspect of this disclosure, signal loss and the acceptable range of signal loss are used as values ​​that reflect fluctuations in gain and deviation, and the resolution of information regarding propagation characteristics is determined based on the acceptable range of signal loss in the current propagation environment.

[0015] More specifically, one aspect of the present disclosure is an information processing device comprising: a control unit that performs the following: obtaining a first acceptable range of signal loss in a user device (UE) based on first information relating to the loss of a signal coordinately transmitted from one or more transmission / reception points (TRPs) to a user device (UE), and second information depending on the requirements of an application; and determining, based on the first acceptable range, the resolution of information relating to the propagation characteristics between the one or more TRPs and the UE, which is reported from the UE to the network.

[0016] The information processing device is, for example, a control device that controls a system including the multiple TRPs and the UE. However, it is not limited to this, and the information processing device may also be a UE, a base station, or a relay station. The control unit provided in the information processing device is, for example, a processor such as a CPU (Central Processing Unit). The UE is, for example, a wireless communication device such as a smartphone, a tablet terminal, and an in-vehicle device. However, it is not limited to this, and the UE may also be a stationary PC (Personal Computer) and a fixedly installed IoT device. Even when the information processing device is a UE, the control unit is a processor such as a CPU. The UE is also called a terminal station, or a mobile station if it is mobile. The TRP is, for example, an antenna and / or antenna port provided in a base station, a relay station, or a UE operating as a relay station. Examples of coordinated transmission from multiple TRPs to a UE include CJT, JT, CoMP (Coordinated Multi-Point), or distributed MIMO.

[0017] The first information and first value related to signal loss are, for example, values ​​of communication quality indicators such as SNR (Signal-to-Noise Ratio), L1-RSRP (Reference Signal Received Power), and RSSI (Received Signal Strength Indicator). Furthermore, for example, when signals are transmitted from multiple TRPs to a UE via CJT, the signal loss indicated by the first information includes the difference between the received signal power in the case of an ideal CJT and the received signal power of the actually received signal. One factor of signal loss in the case of CJT is phase offset. The second information, depending on the application requirements, includes, for example, the MCS index, resource block count, and spatial multiplexing number during MIMO communication, depending on the application requirements. Application requirements include rate, delay, or error rate. The MCS index is an indicator showing the combination of modulation and coding.

[0018] The information regarding the propagation characteristics between the one or more TRPs and the UE reported from the UE to the network includes, for example, interference measurement information such as phase offset, L1-RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), RSSI (Received Signal Strength Indicator), SINR (Signal to Interference plus Noise Ratio), CSI (Channel State Information), and inter-cell interference, all measured by the UE.

[0019] According to one aspect of this disclosure, an acceptable range of signal loss that reflects gain and deviation variations affecting the resolution of propagation characteristics information reported from the UE to the network is determined based on application requirements, and the resolution is determined based on said acceptable range of loss. This makes it possible to set the resolution of propagation characteristics information reported from the UE to the network to an appropriate value under the propagation environment of a communication configuration that satisfies the application requirements.

[0020] In one aspect of the present disclosure, the control unit may determine the resolution applied to the UE based on a first tolerance range and a third piece of information indicating the relationship between the tolerance range of loss and the resolution, wherein the resolution increases as the tolerance range of loss narrows. If the information processing device is the control unit, the third piece of information may be stored in a storage unit in advance. If the information processing device is the UE, the third piece of information may be received from a network. The resolution corresponding to the first tolerance range can be determined based on the third piece of information.

[0021] In one aspect of the present disclosure, the control unit may further perform the following: first information, a second value relating to the signal loss at the UE based on measurements relating to the propagation environment between the one or more TRPs and the UE. In this case, the control unit may obtain a first tolerance range based on the first information and, as second information, a correspondence between MCS indices and first values ​​relating to acceptable loss for one or more first MCS indices according to the requirements of the application. Since the first information is the signal loss at the UE obtained based on measurements and the second information is information including first values ​​relating to acceptable loss according to the requirements of the application, a first tolerance range of signal loss can be obtained in a manner that corresponds to the requirements of the application under the current propagation environment.

[0022] Furthermore, the control unit may obtain the value indicating the smallest loss among the one or more first values ​​corresponding to each of the one or more first MCS indices, and subtract this value indicating the smallest loss from the second value to obtain the first tolerance range. This makes it possible to determine the first tolerance range of signal loss as wide as possible. By determining the first tolerance range of signal loss as wide as possible, it is possible to prevent the resolution of the information reported to the network from being determined to a value that affects the gain and the stability of the communication quality.

[0023] Furthermore, the control unit may further acquire one or more MCS indices from among multiple associations between MCS index, spectral efficiency, and signal loss that are associated with a spectral efficiency equal to or greater than the spectral efficiency required by the application's rate, as the one or more first MCS indices. This makes it possible to determine a first acceptable range of signal loss within the range permitted by the application's requirements.

[0024] Furthermore, the control unit may, in a plurality of correspondences between MCS index, spectral efficiency, and signal loss, acquire as the one or more first MCS index one or more MCS indices that correspond to a first value indicating a loss greater than the loss indicated by the second value, among the one or more second MCS indices that correspond to a spectral efficiency equal to or greater than the spectral efficiency according to the application's required rate. This makes it possible to determine a first acceptable range of signal loss within a range that is acceptable according to the application requirements and within a range that is acceptable under the current propagation environment.

[0025] In this case, the control unit may further instruct the application to reduce the request rate if there is no MCS index among the one or more second MCS indices that corresponds to a first value that indicates a loss greater than the loss indicated by the second value. This can reduce the excessively high request rate from the application and suppress a deterioration in communication quality.

[0026] Furthermore, the control unit may, if the third MCS index used by the one or more TRPs and the UE is not included in the one or more first MCS indexes, determine one of the one or more first MCS indexes as the new third MCS index. This allows the MCS indexes used by the TRPs and UEs to be updated to suit the current propagation environment.

[0027] Furthermore, the control unit may determine the MCS index among the one or more first MCS indices that has the smallest loss indicated by the associated first value as a new second MCS index. This allows the MCS index used by the TRP and UE to be updated to one that can be expected to provide the fastest communication speed in the current propagation environment, that is, one that minimizes signal loss.

[0028] In one aspect of the present disclosure, the control unit may further instruct the UE to transmit an uplink measurement signal and receive measurement values ​​from each of the one or more TRPs based on the uplink measurement signal transmitted from the UE. In this case, the information processing device may be, for example, the control device or one or more of the TRPs. The uplink measurement signal may be an uplink reference signal or an uplink data signal. The reference signal used as the uplink measurement signal may be, for example, an SRS (Sounding Reference Signal), DM (DeMmodulation)-RS, PT (Phase Tracking)-RS, or any other uplink reference signal.

[0029] If the information processing device is either the control device or the TRP, it is connected to one or more TRPs via a wired network, so the wireless resources used by the information processing device to receive the measured values ​​are the wireless resources related to the measurement signals on the uplink from the UE. Therefore, according to one aspect of this disclosure, overhead can be reduced.

[0030] In one aspect of the present disclosure, the control unit may further instruct one or more TRPs to transmit a downlink measurement signal, and receive from the UE a measurement value obtained based on the downlink measurement signal transmitted from one or more TRPs. In this case, the information processing device may be, for example, the control device or one or more TRPs. The downlink measurement signal may be a downlink reference signal, an SSS (Secondary Synchronization Signal), or a downlink data signal. The reference signal used as the downlink measurement signal may be, for example, a CSI (Channel State Information)-RS, DM-RS, PT-RS, PRS (Positioning RS), or any other downlink reference signal.

[0031] In this case, since the propagation characteristics measured by the UE in the direction from one or more TRPs to UE are obtained, the resolution can be determined using more accurate information on the propagation characteristics in the direction from one or more TRPs to UE.

[0032] This disclosure can also be identified in another aspect as a method by which a computer performs the processing of the information processing apparatus. The method involves the computer obtaining a first acceptable range of signal loss at a user device (UE) based on first information relating to signal loss coordinately transmitted from one or more transmission / reception points (TRPs) to a user device (UE) and second information depending on the requirements of an application, and determining, based on the first acceptable range, the resolution of information relating to the propagation characteristics between the one or more TRPs and the UE, which is reported from the UE to the network.

[0033] Another embodiment of the method can also be defined as a program for causing a computer to execute, and a computer-readable, non-temporary storage medium on which the program is recorded.

[0034] Embodiments of this disclosure will be described below with reference to the drawings. The configurations of the following embodiments are illustrative, and this disclosure is not limited to the configurations of these embodiments.

[0035] <First Embodiment> Figure 1 is a diagram showing an example of the system configuration of the communication system 100 according to the first embodiment. The communication system 100 is a distributed MIMO system including user equipment (UE) 2, a control device 1, and a plurality of distributed base stations. The communication system 100 is a wireless communication system of mobile communication methods such as 5G, LTE (Long Term Evolution), and 6G or later. The control device 1 is a device on the core network to which the distributed base stations are connected. However, it can also be considered that the control device 1 is the core network itself, or a system included in the core network. The core network includes, for example, an optical fiber network. The control device 1 controls the distributed base stations and the UE 2.

[0036] The distributed base stations, together with other distributed base stations within the same communication area, provide a wireless access network to UE 2 located within that communication area. The three distributed base stations shown in Figure 1 are assumed to be located within the same communication area. Each distributed base station is connected to the control device 1, for example, via a wired network.

[0037] A distributed base station is equipped with an antenna capable of forming multiple beam patterns. The antenna used in a distributed base station is, for example, an adaptive array antenna. An adaptive array antenna is an array antenna in which multiple antenna elements are arranged. The adaptive array antenna can electrically change the beam pattern by adaptively controlling the weighting of each antenna element according to the radio wave propagation environment. A beam pattern can also be described as the directivity of the beam formed by the adaptive array antenna. The beam pattern of a distributed base station is controlled by a control device 1. A distributed base station may have one antenna or multiple antennas. The beam formed at a distributed base station is identified by an antenna port.

[0038] A base station comprises a Radio Unit (RU), a Distributed Unit (DU), and a Centralized Unit (CU). While distributed base stations may also include RUs and CUs, the minimum configuration requires a DU; therefore, a distributed base station will hereafter be simply referred to as a DU.

[0039] UE 2 is a terminal station such as a smartphone, tablet, wearable device, or in-vehicle data communication device. However, it is not limited to this, and UE 2 may be a stationary terminal device. Alternatively, a relay station that relays wireless communication between a distributed base station and a terminal station can be used as a mobile station instead of UE 2. Relay stations include, for example, small base stations, mobile base stations, in-vehicle devices, and smartphones. In the first embodiment, UE 2 is equipped with one antenna. However, it is not limited to this, and UE 2 may be equipped with multiple antennas.

[0040] In the example shown in Figure 1, the communication system 100 includes three DUs: DU#1, DU#2, and DU#3. Each of DU#1, DU#2, and DU#3 is connected to and controlled by the control device 1. The connection between the control device 1 and each DU is, for example, via a dedicated line or a backbone network. The control device 1 and the UE 2 communicate via a wireless communication control channel through either DU#1, DU#2, or DU#3.

[0041] DU#1, DU#2, and DU#3 perform coordinated transmission to UE 2. In the first embodiment, it is assumed that the three DUs, DU#1, DU#2, and DU#3, perform CJT to UE 2. However, the coordinated transmission performed by DU#1, DU#2, and DU#3 to UE 2 is not limited to CJT, but may be CoMP, CJT, or distributed MIMO. Each of DU#1, DU#2, and DU#3 has two antenna ports. An example of an antenna port provided on a DU is a TRP.

[0042] UE 2 receives signals transmitted from each DU's TRP using each beam pattern. The CJT aims for the signals transmitted from each DU's TRP using each beam pattern to reach UE 2 in phase. To achieve this, it is required that each TRP transmits a carrier wave with phase correction equal to the offset from the received signal from the reference TRP. The reference TRP is selected by the control device 1 from among multiple TRPs that perform coordinated transmission to UE 2.

[0043] The phase offset of the target signal is measured by UE 2 and reported to control device 1. In the first embodiment, control device 1 determines the resolution of the phase offset reported by UE 2 based on the acceptable range of signal loss in UE 2 according to the propagation environment and notifies UE 2 of this. UE 2 reports the phase offset with the resolution determined by control device 1. The phase offset is obtained for each subband of the signal from each TRP. If the resolution is high, the number of bits representing a single phase offset increases, and the data size of the phase offset for each subband of the signal from each TRP reported by UE 2 may increase. In the first embodiment, since the resolution of the phase offset is determined to a value according to the propagation environment, it is possible to suppress the increase in the data size of the phase offset reported by UE 2.

[0044] Figure 2 shows an example of a CJT sequence in the communication system 100 according to the first embodiment. In Figure 2, for simplicity, one DU is shown representing multiple DUs. The processing for multiple DUs is the same. Also, as a premise of Figure 2, it is assumed that the distributed stations that will perform coordinated transmission to UE 2 have already been selected by the control device 1.

[0045] In S111, the control device 1 sends an instruction to the UE 2 to transmit the uplink reference signal. Along with this instruction, information regarding the resources allocated for the uplink reference signal to the UE 2 is also transmitted. Information regarding the resources allocated for measuring the uplink reference signal is also transmitted to each DU. Note that the instruction to transmit the reference signal in S111 may be an instruction for a periodic transmission, or it may be an instruction for a non-periodic transmission for the purpose of determining the resolution MΦ.

[0046] In S112, UE 2 transmits an uplink reference signal. In S113, each DU reports to the control device 1 the measured propagation characteristics with UE 2, which were measured based on the uplink reference signal transmitted from UE 2. The measured propagation characteristics reported in S113 may include, for example, RSRP or RSSI. However, the measured values ​​reported by each DU in S113 are not limited to these.

[0047] Furthermore, if UE 2 has multiple antenna ports, S112 transmits an uplink reference signal from each antenna port provided on UE 2. In S113, each DU acquires measurement values ​​based on the uplink reference signal received at each antenna port provided on each DU, and reports the measurement values ​​of the propagation characteristics between each antenna port provided on UE 2 and each antenna port provided on each DU. However, for simplicity, below we will simply say that UE 2 transmits or receives a reference signal or a data signal, and that DU transmits or receives a reference signal or a data signal.

[0048] In S114, the control device 1 performs a process to determine the resolution MΦ of the phase offset. In the first embodiment, the resolution MΦ is determined based on the measured values ​​reported from each DU. Details of the resolution MΦ determination process will be described later.

[0049] In S115, the control device 1 transmits to the UE 2 information regarding the resources allocated to the downlink reference signal for phase offset measurement, and the resolution MΦ. It also transmits an instruction to each DU to transmit the downlink reference signal for phase offset measurement. Along with this instruction, information regarding the resources allocated to the downlink reference signal is also transmitted to each DU.

[0050] In S116, each DU transmits a downlink reference signal. In S117, UE 2 receives the downlink reference signals from each DU and measures the phase offset from the reference signal for each subband of the received signals from each DU. In S118, UE 2 reports the measured phase offset results for each antenna port of each DU to the control device 1.

[0051] In S119, the control device 1 calculates the phase correction value for each subband relative to the carrier wave of each antenna port of each DU from the measurement results of the phase offset for each antenna port of each DU received from the UE 2. The phase correction value for each subband is obtained, for example, as the value obtained by inverting the sign of the phase offset in that subband. However, this is not limited to this, and the method of determining the phase correction value is not limited to a specific method.

[0052] In S120, the control device 1 notifies each DU of the phase correction values ​​for each subband acquired for each antenna port. In S121, each DU performs phase correction of the carrier wave for each DU port by shifting the phase by the notified phase correction value in each subband of the carrier wave frequency.

[0053] In S122, the control device 1 sends data signals to be transmitted via CJT to each DU, and each DU transmits data using a phase-corrected carrier wave in each subband. In UE 2, the phase-corrected signals received from each DU are combined and reception processing is performed.

[0054] In the example shown in Figure 2, the control device 1 notifies each DU of the phase correction value, and each DU performs the phase correction. However, this is not limited to this, and depending on the performance of the DU, the control device 1 may perform the phase correction of the carrier wave based on the phase correction value, notify the DU of information about the phase-corrected carrier wave, and the DU may transmit the data signal with the phase-corrected carrier wave according to that information.

[0055] Figure 3 illustrates the hardware configuration of the control device 1. The control device 1 includes a CPU 101, a main memory 102, an external memory 103, and a communication device 104. The CPU 101 is also called a processor. The CPU 101 is not limited to a single processor and may be a multi-processor configuration. In addition to the CPU 101, a Graphics Processing Unit (GPU), Digital Signal Processor (DSP), etc., may also be provided. Furthermore, the CPU 101 may be linked with hardware circuits such as a Field Programmable Gate Array (FPGA).

[0056] The CPU 101 executes a computer program that has been loaded into the main memory 102 in an executable format, and provides processing to the control device 1. The main memory 102 stores the computer program executed by the CPU 101, data processed by the CPU 101, etc. The main memory 102 is a Dynamic Random Access Memory (DRAM), Static Random Access Memory (SRAM), Read Only Memory (ROM), etc. Furthermore, the external storage device 103 is used as a storage area that assists the main memory 102, and stores the computer program executed by the CPU 101, data processed by the CPU 101, etc. The external storage device 103 is a hard disk drive, Solid State Drive (SSD), etc. Furthermore, a drive device for a removable storage medium may be connected to the control device 1. Removable storage mediums are, for example, Blu-ray discs, Digital Versatile Discs (DVDs), Compact Discs (CDs), flash memory cards, etc. The CPU 101 is an example of a "control unit" of an "information processing device".

[0057] The communication device 104 communicates with external networks such as distributed base stations and the Internet, for example, via optical fiber. The communication device 104 of the control device 1 may be a single device or a combination of multiple devices. The control device 1 is an example of an "information processing device". Note that the hardware configuration of the control device 1 is not limited to that shown in Figure 3.

[0058] Figure 4 shows an example of the functional configuration of the control device 1. The control device 1 comprises a control unit 11, an MCS index table 12, and loss margin-resolution correspondence information 13. The function of the control unit 11 is achieved by the CPU 101 executing a predetermined program.

[0059] In the first embodiment, the control unit 11 controls the CJT. More specifically, the control unit 11 selects distributed stations to perform coordinated transmission to the UE 2, allocates radio resources for reference signals for phase offset measurement, calculates phase correction values, and notifies the DU and UE 2 of control information and data signals.

[0060] In the resolution MΦ determination process, in the first embodiment, the control unit 11 determines the signal loss in the UE based on the measured values ​​reported from each DU, determines the signal loss margin recognized in the current propagation environment from that loss, and determines the resolution MΦ corresponding to that margin. Details of the resolution MΦ determination process will be described later. The control unit 11 notifies the UE 2 of the determined resolution MΦ.

[0061] The MCS index table 12 and the loss margin-resolution correspondence information 13 are stored in the external storage device of the control device 1. The MCS index table 12 and the loss margin-resolution correspondence information 13 are information used in the resolution MΦ determination process. Details of each will be described later.

[0062] Figure 5 shows an example of an MCS index table 12. The MCS index is an indicator that shows the combination of modulation and coding. The MCS index table shown in Figure 5 is based on the MCS index table shown in Table 5.1.3.1-1 in the 3GPP standard technical specification TS38.214.

[0063] The MCS index table 12 shown in Figure 5 contains MCS index I ＭＣＳ The modulation order, target coding rate, spectrum efficiency, and desired signal-to-noise power ratio are associated and included. The value of the modulation order corresponds to the modulation scheme. The MCS index contains the desired signal-to-noise power ratio Γ(I) when communication is performed using the modulation scheme and coding rate indicated by the MCS index. ＭＣＳ The desired signal-to-noise power ratio Γ(I) is associated with it. ＭＣＳ The value Γ(I) indicates the minimum signal-to-noise power ratio required for stable communication when communication is performed using the modulation scheme and coding rate indicated by the MCS index. ＭＣＳ ) is a theoretical value. In the MCS index table 12 shown in Figure 5, the desired signal-to-noise power ratio Γ(I ＭＣＳ The unit of ) is dB. Since the signal-to-noise power ratio indicates the quality of communication, in the first embodiment, the signal-to-noise power ratio is used as one of the indicators showing the magnitude of signal loss. Therefore, a smaller value of the signal-to-noise power ratio indicates greater loss.

[0064] The MCS index table 12 is used to determine a reference value when calculating the loss margin in the resolution MΦ determination process. The loss margin is also called the allowable range of loss. In the first embodiment, the loss margin is expressed using the signal-to-noise power ratio margin.

[0065] FIG. 6 is a graph showing an example of loss margin-resolution correspondence information 13. In the first embodiment, the graph shown in FIG. 6 is used as the loss margin-resolution correspondence information 13. In the graph shown in FIG. 6, the horizontal axis represents the resolution MΦ, and the vertical axis represents the margin of the signal-to-noise power ratio. That is, the graph shown in FIG. 6 is a graph showing the relationship between the resolution MΦ of the phase offset and the margin of the signal loss for each number of distributed stations. Note that the values in the graph shown in FIG. 6 are 99% values. The graph shown in FIG. 6 may be obtained from, for example, a simulation.

[0066] The loss margin-resolution correspondence information 13 is used to obtain the resolution MΦ corresponding to the obtained loss margin in the determination process of the resolution MΦ. Note that the loss margin-resolution correspondence information 13 is not limited to a graph as shown in FIG. 6. For example, when the relationship between the resolution and the margin is represented by a mathematical formula such as a function, the loss margin-resolution correspondence information 13 may be the function.

[0067] FIG. 7 is an example of a flowchart of the determination process of the resolution MΦ according to the first embodiment. The process shown in FIG. 7 is started, for example, when the start condition of the CJT is satisfied. The start condition of the CJT is, for example, that a decrease in the communication quality of the UE 2 is detected, or that it is detected that the UE 2 has moved to a position with a poor radio wave environment such as the cell edge. These are detected based on, for example, information on propagation characteristics periodically reported from the UE 2. The execution subject of the process shown in FIG. 7 is the CPU 101 of the control device 1, but for convenience, the functional components will be mainly described. The same applies to the following flowcharts. Also, in FIG. 7, for simplicity of explanation, it is assumed that both the DU and the UE have one antenna port each.

[0068] In OP101, the control unit 11 calculates the received signal power P ｎ [dB] to the received signal power P when ideal coherent combining is performed in the UE 2. ＣＪＴ ＮＤＵ n is a variable for identifying the DU and ranges from 1 to N. ＤＵIt takes values ​​within the range of N. ＤＵ This indicates the number of DU units. Received signal power P ｎ In the first embodiment, this is a measured value measured from the most recent reference signal reported by each DU. Received signal power P ＣＪＴ ＮＤＵ It is calculated by the following equation 1. δ in equation 1 ｎ This shows the difference between the transmission power of the reference signal and the transmission power of the data signal during CJT in DU#n.

[0069] In OP102, the control unit 11 determines the signal-to-noise power ratio Γ of the signal during CJT in UE2. ＣＪＴ ＮＤＵ Calculate the signal-to-noise power ratio Γ. ＣＪＴ ＮＤＵ This includes the difference between the received signal power obtained when ideal coherent synthesis is performed by CJT and the actually obtained received signal power. In the first embodiment, the signal-to-noise power ratio Γ ＣＪＴ ＮＤＵ This can be calculated as the SNR value using the following equation 2. Therefore, the signal-to-noise power ratio Γ ＣＪＴ ＮＤＵ The unit is dB. ＵＥ Ｎ This is the noise level at UE 2. ＵＥ Ｎ This may be, for example, measured and reported by UE 2 based on the downlink reference signal before the resolution MΦ determination process, or it may be a required specification value for UE 2.

[0070] In OP103, the control unit 11 retrieves the signal-to-noise power ratio Γ of the signal at CJT in UE 2 from the MCS index table 12. ＣＪＴ ＮＤＵ [dB] or less of the desired signal-to-noise power ratio Γ(I ＭＣＳ ) [dB], that is, the signal-to-noise power ratio Γ at CJT. ＣＪＴ ＮＤＵ The desired signal-to-noise power ratio Γ(I) shows a loss greater than the loss shown by ＭＣＳ The set of MCS indices I that are associated with ) ＭＣＳ Select this option.

[0071] In OP104, the control unit 11 controls the set of MCS indices I selected in OP103. ＭＣＳ From among these, select the desired signal-to-noise power ratio Γ(I ＭＣＳ The MCS index associated with the maximum value of ) is I^ ＭＣＳ Select as: MCS Index I^ ＭＣＳ This corresponds to the desired signal-to-noise power ratio Γ(I ＭＣＳ The value of ) is the maximum, but the set I of the MCS index ＭＣＳ Among these, the MCS index is shown to minimize losses.

[0072] In OP105, the control unit 11 calculates the loss margin Δ Ｍ The signal-to-noise power ratio Γ of the signal during CJT in UE 2 ＣＪＴ ＮＤＵ From the desired signal-to-noise power ratio Γ(I^ ＭＣＳ Subtracting this, the loss margin Δ is obtained from the loss margin - resolution correspondence information 13. Ｍ The maximum MΦ value within the following region is determined as the resolution MΦ of the phase offset of UE 2. For example, if the graph shown in Figure 6 is used as the loss margin-resolution correspondence information 13, the number of DUs is 2, and the loss margin Δ Ｍ If the value is -4, then MΦ is determined to be 4. However, the method for determining the resolution MΦ from the loss margin-resolution correspondence information 13 is not limited to this. After that, the resolution MΦ determination process shown in Figure 7 is completed, and the resolution MΦ of the phase offset is notified to UE 2.

[0073] Note that the resolution MΦ determination process is not limited to the process shown in Figure 7. For example, in OP102, the signal-to-noise power ratio Γ at CJT is ＣＪＴ ＮＤＵ This can be determined using indicators other than SNR. For example, in OP104, I^ ＭＣＳ The MCS index selected is the set of MCS indexes I ＭＣＳ Any of the MCS indices included in it may be used.

[0074] In the example shown in Figure 7, it was explained assuming that each DU and UE 2 is equipped with one antenna port. When both the DU and UE are equipped with multiple antenna ports, the received signal power P in OP101 is... ＣＪＴ ＮＤＵ In the calculation, the received signal power P is calculated for all combinations of antenna port #m provided on UE 2 and antenna ports #n-kn on the DU side. ｍ ｎ，ｋｎ The calculation is performed according to Equation 1. m is a variable that indicates the antenna ports provided on UE 2, and takes values ​​in the range from 1 to M. M is the number of antenna ports provided on UE 2. kn is a variable that indicates the antenna ports provided on DU#n, and takes values ​​in the range from 1 to Kn. Kn is the number of antenna ports provided on DU#n.

[0075] <Effects of the First Embodiment> In the first embodiment, the resolution MΦ of the phase offset reported from UE 2 is equal to the loss margin Δ obtained based on the measured value. Ｍ This is determined based on the following. This allows for a resolution MΦ that is appropriate for the current propagation environment between UE 2 and each DU, and reduces overhead when reporting from UE 2.

[0076] <Modification 1 of the First Embodiment> In the first embodiment, the resolution MΦ is determined using measured values ​​based on the reference signal of the uplink from UE 2. Alternatively, measured values ​​measured by UE 2 based on the reference signal of the downlink from each DU may be used.

[0077] Figure 8 shows an example of the CJT sequence in the communication system 100 according to Modification 1 of the First Embodiment. The assumptions for the example shown in Figure 8 are the same as those for the example shown in Figure 2. In S211, the control device 1 transmits a transmission instruction for the downlink reference signal to each DU. Along with this instruction, information regarding the resources allocated for the downlink reference signal to each DU is also transmitted. Information regarding the resources allocated for measuring the downlink reference signal is also transmitted to the UE 2. Note that in S211, if it is the transmission timing for the SSS, the SSS may be used instead of the downlink reference signal.

[0078] In S212, each DU transmits a downlink reference signal. In S213, UE 2 generates an indicator showing the propagation characteristics with each DU, measured based on the downlink reference signals transmitted from each DU. The indicator may be, for example, RSRP, RSSI, CQI, or / or SNR. However, the indicator is not limited to these.

[0079] In S214, UE 2 reports the indicator to the control device 1. In S215, the control device 1 uses the indicator reported by UE 2 to perform a resolution MΦ determination process. Specifically, in a modified version of the first embodiment, for example, in OP101 of Figure 7, the received signal power P when ideal coherent synthesis is performed. ＣＪＴ ＮＤＵ The calculation involves the received signal power P between UE 2 and DU#n, which is included in the indicator reported by UE 2. ｎ This is used.

[0080] Thereafter, in the same manner as in the first embodiment, the resolution MΦ is notified to UE 2 (S216), the phase offset is measured by UE 2 based on the downlink reference signal (S217, S218), the phase offset is reported to the control device 1 (S219), and phase offset correction is performed. The resolution of the phase offset reported in S219 is MΦ.

[0081] In the first embodiment, modification 1, the resolution MΦ is determined using an indicator measured by UE, so the resolution MΦ can be determined based on a value that more accurately reflects the actual propagation environment.

[0082] <Modification 2 of the First Embodiment> In the resolution MΦ determination process of the first embodiment, the signal-to-noise power ratio Γ at CJT in UE 2 ＣＪＴ ＮＤＵ [dB] or less of the desired signal-to-noise power ratio Γ(I ＭＣＳ ) A set of MCS indices I that are associated with [dB] ＭＣＳ The following is selected. In the modified example 2 of the first embodiment, the set I of the MCS index is selected. ＭＣＳ You may use this to update the currently applied MCS index.

[0083] Figure 9 is an example of a flowchart of the MCS index update process according to Modification 2 of the First Embodiment. The process shown in Figure 9 is started, for example, when the resolution MΦ determination process shown in Figure 7 is completed.

[0084] In OP121, the control unit 11 determines that the MCS index currently applied to UE 2 and each DU is set to set I ＭＣＳ Determine whether or not it is included in set I. ＭＣＳ If it is included in (OP121: YES), the process shown in Figure 9 is terminated. The currently applied MCS index is set I ＭＣＳ If it is not included (OP122: NO), the process proceeds to OP122.

[0085] In OP122, the control unit 11 is set up I ＭＣＳ Among the MCS indices included, the signal-to-noise power ratio Γ(I ＭＣＳ The MCS index I^ is associated with the maximum value of ) ＭＣＳ The MCS index to be newly applied to UE 2 and each DU is determined. After that, the process shown in Figure 9 is completed. Then, the control unit 11 updates the MCS index and the newly applied MCS index I^ for each DU and UE 2. ＭＣＳ To notify them of this.

[0086] Note that the process shown in Figure 9 is just one example, and the MCS index update process is not limited to the process shown in Figure 9. For example, in OP122, the newly applied MCS index is set I ＭＣＳ The MCS index included may be randomly selected.

[0087] In the resolution MΦ determination process of the first embodiment, the signal-to-noise power ratio Γ at CJT in UE 2 ＣＪＴ ＮＤＵ [dB] or less of the desired signal-to-noise power ratio Γ(I ＭＣＳ ) A set of MCS indices I that are associated with [dB] ＭＣＳ This is an MCS index that can satisfy the signal-to-noise power ratio required for stable communication in the current propagation environment between UE 2 and each DU. The set of MCS indices I ＭＣＳ By updating the MCS index included in the system, it becomes possible to ensure a signal-to-noise power ratio that satisfies the desired signal-to-noise power ratio associated with the updated MCS index, thereby stabilizing communication.

[0088] <Second Embodiment> In the second embodiment, the loss margin used to determine the resolution MΦ of the phase offset is determined based on the application's required rate. In the second embodiment, explanations common to the first embodiment are omitted. The hardware configuration (Figure 3) and functional configuration (Figure 4) of the control device 1 in the second embodiment, and the CJT sequence (see Figure 2) are the same as in the first embodiment.

[0089] Figure 10 is an example of a flowchart for determining the resolution MΦ according to the second embodiment. The process shown in Figure 10 is started, for example, when the CJT start condition is met. Also, for the sake of simplicity of explanation, Figure 10 assumes that both DU and UE are equipped with one antenna port each.

[0090] In OP201, the control unit 11 determines the spectral efficiency S according to the request rate from the application of the communication being performed by UE 2. ＲＥＱCalculate the desired spectral efficiency S of the application. ＲＥＱ Is calculated using the following Equation 3. R ＲＥＱ Is the required rate of the application. N ＲＢ Is the number of resource blocks available in the channel. Δ ｆ Is the sub-carrier spacing of the channel. N ｆ Is the number of sub-carriers.

[0091] In OP202, the control unit 11 obtains the set I of MCS indexes from the MCS index table 12 that is greater than or equal to the desired spectral efficiency S of the application. ＲＥＱ Of the above MCS indexes. ＲＥＱ To obtain.

[0092] In OP203, the control unit 11 calculates the received signal power P from the received signal power P [dB] between the UE and the DU#n, when ideal coherent combining is performed in the UE 2. ｎ From [dB], the received signal power P when ideal coherent combining is performed in the UE 2. ＣＪＴ ＮＤＵ To calculate. The received signal power P ｎ Is, in the second embodiment, the measured value measured from the most recent reference signal reported from each DU. The received signal power P ＣＪＴ ＮＤＵ Is calculated by the above Equation 1. In OP204, the control unit 11 calculates the signal-to-noise power ratio Γ at the time of CJT in the UE 2 as described in the above Equation 2, by subtracting the noise level P in the UE 2 from the received signal power P calculated in OP203. ＣＪＴ ＮＤＵ From the received signal power P ＣＪＴ ＮＤＵ Calculated in OP203. ＵＥ Ｎ To calculate.

[0093] In OP205, the control unit 11 selects, as I^, the MCS index associated with the minimum value of the desired signal-to-noise power ratio Γ(I) from the set I of MCS indexes selected in OP202. However, it is not limited to this, and I^ ＲＥＱ Of the desired signal-to-noise power ratio Γ(I ＲＥＱ ). ＲＥＱ To select as. However, it is not limited to this, and I^ ＲＥＱ Is the set I ＲＥＱYou may randomly select from the MCS indices included in set I ＲＥＱ The desired signal-to-noise power ratio Γ(I) in the MCS index included in ＲＥＱ An MCS index corresponding to the median of ) may be selected.

[0094] In OP206, the control unit 11 controls the loss margin Δ Ｍ＿ＲＥＱ The signal-to-noise power ratio Γ at CJT in UE 2 ＣＪＴ ＮＤＵ From the desired signal-to-noise power ratio Γ(I^ ＲＥＱ Subtracting this, the loss margin Δ is obtained from the loss margin - resolution correspondence information 13. Ｍ＿ＲＥＱ The maximum MΦ value within the following region is determined as the resolution MΦ of the phase offset of UE 2. After that, the resolution MΦ determination process shown in Figure 10 is completed, and the resolution MΦ of the phase offset is notified to UE 2.

[0095] Furthermore, if both DU and UE are equipped with multiple antenna ports, the received signal power P in OP203 is the same as in the first embodiment. ＣＪＴ ＮＤＵ In calculating the received signal power P, all combinations of the antenna port provided on UE 2 and the antenna port on the DU side are considered. ｍ ｎ，ｋｎ The calculation is performed according to Equation 1.

[0096] Furthermore, following the resolution MΦ determination process shown in Figure 10, set I ＲＥＱ Regarding this, the MCS index update process shown in Figure 9 may be performed. Set I ＲＥＱ When the MCS index update process shown in Figure 9 is performed, in OP122, the newly applied MCS index is set I. ＲＥＱ Among the MCS indices included, the desired signal-to-noise power ratio Γ(I ＲＥＱ The MCS index I^ is associated with the minimum value of ) ＲＥＱ This may be determined as the new MCS index to be applied to UE 2 and each DU. However, it is not limited to this.

[0097] <Effects of the Second Embodiment> In the second embodiment, the resolution MΦ of the phase offset reported from UE 2 is obtained based on the loss margin Δ obtained based on the application's required rate. Ｍ＿ＲＥＱ It is determined based on this. This allows the resolution MΦ to be set according to the MCS index such that the application's required rate is achieved. If the application's required rate is high, I^ ＲＥＱ The MCS index selected and the value indicating the desired signal-to-noise power ratio corresponding to that MCS index also increase, and the loss margin Δ Ｍ＿ＲＥＱ This also increases the resolution MΦ of the phase offset reported by the UE (Figure 6), allowing for finer adjustment of the signal phase error and maintaining communication quality. When the application's required rate is low, I^ ＲＥＱ The MCS index selected and the value indicating the desired signal-to-noise power ratio corresponding to that MCS index also become smaller, and the loss margin Δ Ｍ＿ＲＥＱ This also reduces the size. As a result, the resolution MΦ of the phase offset reported by the UE (Figure 6) can be set smaller, and the data size of the phase offset reported by UE 2 can also be kept small.

[0098] <Modification 1 of the Second Embodiment> In Modification 1 of the Second Embodiment, the loss margin used to determine the resolution MΦ of the phase offset is determined by considering not only the application's required rate but also the measured values ​​of the propagation characteristics between UE 2 and each DU.

[0099] Figure 11 is an example of a flowchart for determining the resolution MΦ according to Modification 1 of the second embodiment. The starting conditions and premises for the process shown in Figure 11 are the same as those in Figure 10. The processing from OP221 to OP224 is the same as the processing from OP201 to OP204 in Figure 10. The processing from OP221 to OP224 determines the spectral efficiency S according to the request rate from the application. ＲＥＱ The desired spectral efficiency S of the application is calculated (OP221). ＲＥＱ The above is a set of MCS indices I ＲＥＱThe received signal power P is obtained (OP222) when ideal coherent synthesis is performed. ＣＪＴ ＮＤＵ The following is calculated (OP223): the signal-to-noise power ratio Γ during CJT. ＣＪＴ ＮＤＵ This is calculated (OP224).

[0100] In OP225, the control unit 11 retrieves the signal-to-noise power ratio Γ at CJT in UE2 from the MCS index table 12. ＣＪＴ ＮＤＵ [dB] or less of the desired signal-to-noise power ratio Γ(I ＭＣＳ ) [dB] corresponds to the signal-to-noise power ratio Γ at CJT. ＣＪＴ ＮＤＵ The desired signal-to-noise power ratio Γ(I) shows a loss greater than the loss shown by ＭＣＳ The set of MCS indices I that are associated with ) ＭＣＳ Select this option.

[0101] In OP226, the control unit 11 is set up I ＲＥＱ and set I ＭＣＳ Determine whether there are any overlapping MCS indices in set I. ＲＥＱ and set I ＭＣＳ If there are overlapping MCS indices (OP226: YES), the process proceeds to OP227. In OP227, the control unit 11 processes set I ＭＣＳ Of these, set I ＲＥＱ From among the MCS indices that overlap, select the desired signal-to-noise power ratio Γ(I ＭＣＳ The MCS index associated with the maximum value of ) is I^ ＭＣＳ Select it as such.

[0102] In OP228, the control unit 11 controls the loss margin Δ Ｍ The signal-to-noise power ratio Γ of the signal during CJT in UE 2 ＣＪＴ ＮＤＵ From the desired signal-to-noise power ratio Γ(I^ ＭＣＳ Subtracting this, the loss margin Δ is obtained from the loss margin - resolution correspondence information 13. ＭThe maximum MΦ value within the following region is determined as the resolution MΦ of the phase offset of UE 2. After that, the resolution MΦ determination process shown in Figure 11 is completed, and the resolution MΦ of the phase offset is notified to UE 2.

[0103] In OP226, set I ＲＥＱ and set I ＭＣＳ If there are no overlapping MCS indices (OP226: NO), the process proceeds to OP229. In OP229, the control unit 11 sends an instruction to the application to reduce the request rate. This instruction is sent, for example, to a server that controls the application. After that, the process shown in Figure 11 is completed. Note that following the resolution MΦ determination process shown in Figure 11, the MCS index update process shown in Figure 9 may be performed.

[0104] In the modified version 1 of the second embodiment, the loss margin is determined by considering not only the application's required rate but also the measured propagation characteristics between UE 2 and each DU. This allows the resolution MΦ to be set to a value that does not affect the achievement of a transmission speed that satisfies the application's required rate and maintains the stability of the current propagation environment.

[0105] Furthermore, in the modified example 1 of the second embodiment, set I ＲＥＱ and set I ＭＣＳ If there are no overlapping MCS indices, it indicates that the application's request rate is too high for the current propagation environment. If the application's request rate is too high, it can lead to a decrease in communication speed, packet loss, errors, and a decline in communication quality. According to Modification 1 of the Second Embodiment, if it is detected that the application's request rate is too high, an instruction is given to the application to reduce its request rate, thereby guiding the application's request rate to an appropriate rate for the current propagation environment.

[0106] Also, for example, set I ＲＥＱ and set I ＭＣＳ If there are no overlapping MCS indices, the control device 1 will set up set I ＭＣＳThe desired signal-to-noise power ratio Γ(I^) is the maximum value in this case. ＭＣＳ Based on this, the reduction in the request rate or the reduced request rate may be calculated and notified to the application along with an instruction to reduce the request rate.

[0107] <Modification 2 of the Second Embodiment> In the second embodiment, the resolution MΦ determination process (Figure 10) is performed using the measured values ​​of the propagation characteristics between UE 2 and each DU, acquired by each DU based on the uplink reference signal, in the CJT sequence shown in Figure 2. In Modification 2 of the second embodiment, instead, the resolution MΦ determination process (Figure 10) is performed using the measured values ​​(indicators) of the propagation characteristics between UE 2 and each DU, acquired by UE 2 based on the downlink reference signal, in the CJT sequence shown in Figure 8. Alternatively, in the CJT sequence shown in Figure 8, the resolution MΦ determination process in Modification 2 of the second embodiment shown in Figure 11 may be performed instead of the resolution MΦ determination process shown in Figure 10.

[0108] <Third Embodiment> In the third embodiment, UE 2 performs the resolution MΦ determination process (Figure 7) which is performed by the control device 1 in the first embodiment. In the third embodiment, explanations common to the first embodiment are omitted.

[0109] Figure 12 shows an example of the CJT sequence in the communication system 100 according to the third embodiment. The assumptions for the example shown in Figure 12 are the same as those for the example shown in Figure 2. In S311, the control device 1 sends a transmission instruction for the downlink reference signal to each DU. Along with this instruction, information regarding the resources allocated for the downlink reference signal to each DU is also transmitted. Information regarding the resources allocated for measuring the downlink reference signal is also transmitted to the UE 2. Furthermore, in the third embodiment, the control device 1 notifies the UE 2 of the loss margin-resolution correspondence information 13 as a calculation condition for the resolution MΦ. Note that in S311, if it is the transmission timing for the SSS, the SSS may be used instead of the downlink reference signal. The control device 1 notifies the UE 2 of the calculation condition for the resolution MΦ, for example, when the CJT start condition is met.

[0110] In S312, each DU transmits a downlink reference signal. In S313, UE 2 measures the propagation characteristics with each DU based on the downlink reference signals transmitted from each DU, and uses the measured value and the loss margin-resolution correspondence information 13 received from the control device 1 to perform a resolution MΦ determination process similar to the process shown in Figure 7. In S314, UE 2 reports to the control device 1 the phase offset MΦ obtained as a result of the resolution MΦ determination process performed in S313.

[0111] Thereafter, in the same manner as the CJT sequence of the first embodiment (Figure 2), each DU transmits a downlink reference signal according to instructions from the control device 1 (S315, 316), the UE 2 measures the downlink reference signal and measures the phase offset (S317), the phase offset is reported to the control device 1 (S318), and phase offset correction is performed.

[0112] Figure 13 shows an example of the hardware configuration of UE 2. UE 2 includes a CPU 201, main memory 202, external storage device 203, wireless communication device 204, and antenna 205. The CPU 201, main memory 202, and external storage device 203 are the same as those of CPU 101, main memory 102, and external storage device 103.

[0113] The wireless communication device 204 is connected to the antenna 205 and, through the antenna 205, connects to a wireless access network, for example, by a 5G or later mobile wireless communication system, and receives wireless signals from distributed base stations. The wireless communication device 204 is also connected to the control device 1 on the control plane. Note that the hardware configuration of UE 2 is not limited to that shown in Figure 13. Depending on the type, UE 2 may further include a touch panel display, microphone, speaker, and operation buttons in addition to the components shown in Figure 12.

[0114] Figure 14 shows an example of the functional configuration of UE 2. UE 2 comprises a control unit 21, a measurement unit 22, and an MCS index table 23. The functions of the control unit 21 and the measurement unit 22 are achieved by the CPU 201 executing a predetermined program.

[0115] The control unit 21 controls the measurement and reporting of periodic or aperiodic radio wave propagation characteristics in UE 2. The control unit 21 receives the allocation of radio resources for measuring radio wave propagation characteristics and the allocation of radio resources for reporting from the control device 1. The control unit 21 outputs the allocation of radio resources for measuring radio wave propagation characteristics to the measurement unit 22. The control unit 21 receives the measurement results of the radio wave propagation characteristics of the downlink reference signal (e.g., CSI-RS) transmitted from each DU from the measurement unit 22. The control unit 21 uses the reporting radio resources notified by the control device 1 to report information regarding radio wave propagation characteristics as measurement results to the control device 1.

[0116] In the third embodiment, the control unit 21 performs a resolution MΦ determination process using the measured values ​​of the propagation characteristics between each DU, measured based on the downlink reference signal transmitted from each DU, and the loss margin-resolution correspondence information 13 received from the control device 1 as a calculation condition for the resolution MΦ. The resolution MΦ determination process performed by the control unit 21 is the same as the process shown in Figure 7, except that it uses the measured values ​​of the propagation characteristics between each DU, measured based on the downlink reference signal transmitted from each DU, and the loss margin-resolution correspondence information 13 received from the control device 1 as a calculation condition.

[0117] The measurement unit 22 receives input from the control unit 21 regarding information about the distributed stations to be measured and the allocation of radio resources for measuring radio wave propagation characteristics, which are notified by the control device 1. The measurement unit 22 receives the downlink reference signal transmitted from each DU via the UE port according to the allocation of radio resources for measuring radio wave propagation characteristics. Each time the measurement unit 22 receives a downlink reference signal, it estimates the radio wave propagation characteristics of the downlink reference signal from each DU port and outputs the measurement result to the control unit 21 as one of the measurement results. The radio wave propagation characteristics of the downlink reference signal measured by the measurement unit 22 include, for example, propagation characteristics (channel response), phase offset, RSRP, RSSI, RSRQ, CSI, and SINR.

[0118] The MCS index table 23 is, for example, the MCS index table shown in Figure 5. Since the UE 2 also maintains a common MCS index table with the control device 1 and each DU, the applicable modulation scheme and coding rate can be identified by notifying only the MCS index. Note that the functional configuration of the UE 2 is not limited to the example shown in Figure 14.

[0119] <Effects of the Third Embodiment> In the third embodiment, UE 2 performs the resolution MΦ determination process. In this case, in the sequence related to the resolution MΦ determination process (for example, S311 to S314 in Figure 12), UE 2 transmits only when notifying the control device 1 of the determined resolution MΦ. Normally, transmitting a signal consumes more power than receiving a signal. Therefore, when UE 2 performs the resolution MΦ determination process as in the third embodiment, the power consumption of UE 2 can be kept low. In addition, by reducing the transmission of signals from UE 2, the amount of wireless resources allocated to data communication can be increased.

[0120] Furthermore, when UE 2 performs the resolution MΦ determination process, UE 2 may, for example, perform the MCS index update process shown in Figure 9. In this case, after the MCS index update process, UE 2 may notify the control device 1 of the MCS index that it has decided to apply.

[0121] <Fourth Embodiment> In the fourth embodiment, UE 2 determines the resolution MΦ in the same manner as in the second embodiment, which is performed by the control device 1. In the fourth embodiment, descriptions common to the first to third embodiments are omitted. In the fourth embodiment, the hardware configuration (Figure 13) and functional configuration (Figure 14) of UE 2, and the CJT sequence (Figure 12) are the same as in the third embodiment.

[0122] The difference between the resolution MΦ determination process performed by the control device 1 in the second embodiment (Figure 10) and the process in which the UE 2 determines the resolution MΦ in the fourth embodiment is that the UE 2 determines the resolution MΦ from a set of MCS indices I corresponding to the request rate from the application. ＲＥＱ The key difference is that the acquisition of this information (OP201-OP202 in Figure 10) is not performed. This is because information such as the request rate of the higher-layer application is basically handled on the network side and is therefore often notified to the control unit without being notified to UE 2.

[0123] In the fourth embodiment, the control device 1 controls a set of MCS indices I corresponding to the request rate from the application. ＲＥＱObtain set I ＲＥＱ The loss margin - resolution correspondence information 13 is sent to UE 2 as calculation conditions (S311 in Figure 12). UE 2 receives the set I from the control device 1. ＲＥＱ Using the loss margin-resolution correspondence information 13 and the measured value based on the downlink reference signal, for example, the processing from OP203 to OP206 in Figure 10 is performed. As a result, the resolution MΦ is also determined by UE 2 based on the application's requested rate. In addition, in UE 2, after determining the resolution MΦ, set I ＲＥＱ Regarding this, the MCS index update process shown in Figure 9 may be performed.

[0124] <Modification of the Fourth Embodiment> In the modification of the fourth embodiment, UE 2 determines the resolution MΦ in the same manner as performed by the control device 1 in Modification 1 of the second embodiment. The differences between the resolution MΦ determination process performed by the control device 1 in Modification 1 of the second embodiment (Figure 11) and the process in which UE 2 determines the resolution MΦ in the modification of the fourth embodiment are the same as in the fourth embodiment.

[0125] In a modified version of the fourth embodiment, the control device 1 controls a set of MCS indices I corresponding to the application's request rate. ＲＥＱ Obtain set I ＲＥＱ The loss margin - resolution correspondence information 13 is sent to UE 2 as calculation conditions (S311 in Figure 12). UE 2 receives the set I from the control device 1. ＲＥＱ Using the loss margin-resolution correspondence information 13 and the measured value based on the downlink reference signal, for example, the processing from OP223 to OP228 in Figure 11 is performed. In this way, UE 2 also determines the resolution MΦ by considering the measured value of the propagation characteristics between each DU in addition to the application's requested rate. Note that in UE 2 as well, the MCS index update processing shown in Figure 9 may be performed after the resolution MΦ has been determined.

[0126] Furthermore, in a modified example of the fourth embodiment, a set of MCS indices I corresponding to the application's request rate ＲＥＱ And the signal-to-noise power ratio Γ during CJT.ＣＪＴ ＮＤＵ The desired signal-to-noise ratio Γ(I) exhibits a loss greater than the loss shown by ＭＣＳ The set of MCS indices I that are associated with ) ＭＣＳ If there are no overlapping MCS indices (OP226: NO in Figure 11), UE 2 may send a suggestion to control unit 1 to reduce the application request rate.

[0127] <Other Embodiments> The embodiments described above are merely examples, and this disclosure may be modified as appropriate without departing from its essence.

[0128] The first to fourth embodiments described how to determine the resolution MΦ of the phase offset reported from the UE 2 to the control device 1. However, the process for determining the resolution MΦ described in the first to fourth embodiments is also applicable when reporting information on propagation characteristics other than phase offset, such as CSI, RSRP, RSRQ, and SINR. When applied to reporting information on propagation characteristics other than phase offset, loss margin-resolution correspondence information 13 measured for the information on such propagation characteristics may be used.

[0129] In the first to fourth embodiments, the propagation characteristics between UE 2 and each DU are measured using a reference signal, but are not limited to this, and signals other than the reference signal, such as data signals, may be used.

[0130] In the first to fourth embodiments, the explanation was based on the premise that CJT is performed in a distributed MIMO system. However, it is not limited to this, and the resolution MΦ determination process described in the first to fourth embodiments can also be applied to systems in which multiple base stations cooperate to increase the received signal power or received signal strength at the UE, such as CoMP, beamforming, and various MIMOs, and to systems in which multiple base stations cooperate to suppress the effects of interference at the UE, such as distributed null steering and interference null forming. In a broader sense, the resolution MΦ determination process described in the first to fourth embodiments can be applied to systems in which at least multiple antenna ports are provided on the base station side, and technologies are used to improve the communication quality of the UE through the interaction of signals transmitted from the multiple antenna ports to the UE. However, the method for determining the index indicating the magnitude of signal loss used in the resolution MΦ determination process may be appropriately changed depending on the system to which it is applied.

[0131] The processing of the control device 1 in the first or second embodiment, or the processing of the control device 1 in the third or fourth embodiment, may be performed by one of the relay stations if the signal to any of the base stations or UE 2 among the distributed stations is relayed by one or more relay stations.

[0132] Furthermore, the processes and methods described in this disclosure can be freely combined and implemented, provided that no technical inconsistencies arise.

[0133] Furthermore, a process described as being performed by a single device may be divided and executed by multiple devices. Conversely, a process described as being performed by different devices may be executed by a single device. In a computer system, the hardware configuration (server configuration) by which each function is implemented can be flexibly changed.

[0134] The present disclosure can also be realized by supplying a computer program implementing the functions described in the embodiments above to a computer, and having one or more processors in the computer read and execute the program. Such a computer program may be provided to the computer by a non-temporary computer-readable storage medium that can be connected to the computer's system bus, or it may be provided to the computer via a network. The non-temporary computer-readable storage medium includes any type of disk, such as magnetic disks (floppy disks, hard disk drives (HDDs), etc.), optical disks (CD-ROMs, DVDs, Blu-ray discs, etc.), read-only memory (ROM), random access memory (RAM), EPROM, EEPROM, magnetic cards, flash memory, or optical cards, and any type of medium suitable for storing electronic instructions.

[0135] 1. Control device 2. UE 11. Control unit 12. MCS index table 13. Loss margin - resolution correspondence information 23. MCS index table 100. Communication system 101. CPU 102. Main memory 103. External memory 104. Communication device

Claims

1. An information processing device comprising: a control unit that performs the following: first information relating to the loss of a signal coordinately transmitted from one or more transmission / reception points (TRPs) to a user device (UE), and second information according to the requirements of an application; and determining the resolution of information relating to the propagation characteristics between the one or more TRPs and the UE, which is applied to the UE and reported from the UE to the network, based on the first tolerance range.

2. The information processing apparatus according to claim 1, wherein the control unit determines the resolution applied to the UE based on a third piece of information indicating a relationship between the allowable range of loss and the resolution, wherein the resolution increases as the allowable range of loss narrows, and the first allowable range.

3. The information processing apparatus according to claim 2, wherein the control unit further performs the following: obtaining a second value relating to the signal loss in the UE based on measured values ​​relating to the propagation environment between the one or more TRPs and the UE as first information; and obtaining a first tolerance range based on the first information and, as second information, a correspondence between the MCS index and a first value relating to the allowable loss for one or more first MCS (Modulation and Coding Scheme) indices according to the requirements of the application.

4. The information processing apparatus according to claim 3, wherein the control unit obtains a first value from among the one or more first values ​​corresponding to each of the one or more first MCS indices that indicates the smallest signal loss, and subtracts the value from the one or more first values ​​that indicates the smallest loss from the second value to obtain the first allowable range.

5. The information processing apparatus according to claim 3, further comprising the control unit acquiring one or more MCS indices from among a plurality of associations between MCS index, spectral efficiency, and signal loss that are associated with a spectral efficiency equal to or greater than the spectral efficiency corresponding to the application's required rate, as the one or more first MCS indices.

6. The information processing apparatus according to claim 3, further comprising the control unit acquiring, in a plurality of correspondences between MCS index, spectral efficiency and signal loss, one or more MCS indices that correspond to a first value indicating a loss greater than the loss indicated by the second value, from among one or more second MCS indices that correspond to a spectral efficiency greater than or equal to the spectral efficiency according to the application's required rate, as the one or more first MCS indices.

7. The information processing apparatus according to claim 6, wherein the control unit further instructs the application to reduce the request rate if there is no MCS index among the one or more second MCS indices that corresponds to a first value indicating a loss greater than the loss indicated by the second value.

8. The information processing apparatus according to claim 3, wherein the control unit further determines one of the one or more first MCS indexes as a new third MCS index if the third MCS index used by the one or more TRPs and the UE is not included in the one or more first MCS indexes.

9. The information processing apparatus according to claim 8, wherein the control unit determines the MCS index among the one or more first MCS indices that has the smallest loss indicated by the associated first value as the new third MCS index.

10. The information processing apparatus according to claim 5, further comprising a storage unit for storing the third information and a plurality of associations between the MCS index, spectrum efficiency, and signal loss.

11. The information processing apparatus according to claim 3, wherein the control unit further performs the following: instructs the UE to transmit a measurement signal for the uplink; and receives the measurement value obtained from each of the one or more TRPs based on the measurement signal for the uplink transmitted from the UE.

12. The information processing apparatus according to claim 3, wherein the control unit further performs the following: instructs the plurality of TRPs to transmit a measurement signal for the downlink; and receives from the UE the measurement value obtained based on the measurement signal for the downlink transmitted from one or more TRPs.

13. The information processing apparatus according to claim 1, wherein the control unit further performs the action of notifying the UE of the resolution to be applied to the UE that has been determined.

14. A method for a computer to perform the following: obtain a first acceptable range of signal loss in a user device (UE) based on first information relating to the loss of a signal coordinately transmitted from one or more transmission / reception points (TRPs) to a user device (UE), and second information depending on the requirements of an application; and determine, based on the first acceptable range, the resolution of information relating to the propagation characteristics between the one or more TRPs and the UE, which is applied to the UE and reported from the UE to the network.

15. The method of claim 14, wherein the computer determines the resolution to be applied to the UE based on a third piece of information indicating a relationship between the acceptable range of loss and the resolution, wherein the resolution is higher as the acceptable range of loss narrows, and a first acceptable range.

16. The method according to claim 15, wherein the computer further obtains, as first information, a second value relating to the signal loss in the UE based on measurements relating to the propagation environment between the one or more TRPs and the UE, and obtains the first tolerance range based on the first information and, as second information, a correspondence between MCS indices and first values ​​relating to allowable loss for one or more first MCS (Modulation and Coding Scheme) indices according to the requirements of the application.

17. The method according to claim 16, wherein the computer obtains a first value from among the one or more first values ​​corresponding to each of the one or more first MCS indices that indicates the smallest signal loss, and obtains a first tolerance range by subtracting from the second value the value from among the one or more first values ​​that indicates the smallest loss.

18. The method according to claim 16, further comprising the computer acquiring, in a plurality of correspondences between MCS index, spectral efficiency and signal loss, one or more MCS indices that correspond to a first value indicating a loss greater than the loss indicated by the second value, from among one or more second MCS indices that correspond to a spectral efficiency greater than or equal to the spectral efficiency corresponding to the required rate of the application, as the one or more first MCS indices.

19. The method of claim 18, further comprising the computer instructing the application to reduce the request rate if there is no MCS index among the one or more second MCS indices that corresponds to a first value indicating a loss greater than the loss indicated by the second value.

20. A program for causing a computer to perform the following: first information relating to the loss of signals transmitted in coordination from one or more transmission / reception points (TRPs) to a user device (UE), and second information depending on the requirements of an application, to obtain a first acceptable range for the loss of the signal in the UE; and, based on the first acceptable range, to determine the resolution of information relating to the propagation characteristics between the one or more TRPs and the UE, which is applied to the UE and reported from the UE to the network.

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