Method, information processing device, user equipment, and program

Abstract

According to the present invention, overheads caused by reporting of phase offsets from a device that receives signals transmitted cooperatively from a plurality of transmitting and receiving points are reduced. A computer executes: acquisition of first information relating to a change in phase of a first signal transmitted from a first transmission / reception point that, in cooperation with at least one other transmission / reception point, transmits signals to be combined in a first device to the first device; and determination, on the basis of the first information, of the timing at which the first device is to report a phase offset at the first device, the phase offset being the phase difference of the first signal from a reference signal.

Description

Method, Information Processing Apparatus, User Equipment, and Program

[0001] The present disclosure relates to wireless communication.

[0002] In wireless communication such as the 5th Generation Mobile Communication System (5G), distributed MIMO (Multi-Input Multi-Output) is presented in which, among a plurality of distributed stations distributed within the communication area of one base station, one or a plurality of distributed stations near the mobile station are selected for communication. According to distributed MIMO, by appropriately combining radio waves simultaneously transmitted from a plurality of distributed stations, the received signal power at the mobile station can be improved and the throughput can be increased. Also, in distributed MIMO, since the base stations are distributed, the dead zone of radio waves can be reduced and the influence of obstacles can be reduced.

[0003] In coordinated transmission between a plurality of distributed base stations (mTRP, hereinafter referred to as distributed stations) such as distributed MIMO, a technique called Coherent Joint Transmission (CJT) is used to improve the received signal power when signals from each distributed station are combined by ensuring that the transmission signals from each distributed station are received in the same phase at the UE (User Equipment). For example, in coordinated transmission by N distributed stations, assuming that the transmission power of each distributed station is equal, theoretically, by CJT, the received signal power at the UE is N squared times the received signal power of a signal from one distributed station. By improving the received signal power by CJT, improvement in throughput and reduction in latency can be achieved.

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

[0005] One method for reporting phase offset by a UE is to divide the channel bandwidth of a transmitted signal from a single distributed station into a predetermined number of subbands, measure the phase offset for each subband, and report it (for example, Non-Patent Document 1). It has also been disclosed that the reporting of the phase offset measurement results may be periodic, semi-permanent, or aperiodic (for example, Non-Patent Document 2).

[0006] 3GPP TSG RAN WG1 #117 R1-2405486 (2024-05-20)3GPP TSG RAN WG1 #118 RAN1 Chair's Notes (2024-08-19)

[0007] One aspect of this disclosure is to provide a method, information processing device, user device, and program capable of reducing the overhead caused by reporting phase offsets from a device that receives signals transmitted in coordination from multiple transmission and reception points.

[0008] One aspect of the present disclosure is a method in which a computer acquires first information relating to a phase change of a first signal transmitted from a first transmitting point that transmits a signal synthesized in the first device to the first device in coordination with at least one other transmitting point, and determines, based on the first information, the timing at which the first device reports a phase offset, which is the phase difference of the first signal from a reference signal.

[0009] Another aspect of the present disclosure is an information processing device comprising: a control unit that performs: acquiring first information relating to a phase change of a first signal transmitted from a first transmitting / receiving point that transmits a signal synthesized in the first device to the first device in coordination with at least one other transmitting / receiving point; and determining, based on the first information, the timing at which the first device reports a phase offset, which is the phase difference of the first signal from a reference signal.

[0010] Another aspect of the present disclosure is a program for causing a computer to perform the following: acquire first information relating to a phase change of a first signal transmitted from a first transmitting point that transmits a signal synthesized in the first device to the first device in coordination with at least one other transmitting point; and determine, based on the first information, the timing at which the first device reports a phase offset, which is the phase difference of the first signal from a reference signal.

[0011] Another aspect of the present disclosure is a method by which user equipment (UE) combines at least two received signals transmitted in coordination from a first transmitting / receiving point and at least one other transmitting / receiving point, and reports a phase offset, which is the phase difference of the first signal from a reference signal, at a timing determined based on first information relating to a phase change of the first signal transmitted from the first transmitting / receiving point.

[0012] Another aspect of the present disclosure is a user device comprising a control unit that performs: synthesizing at least two received signals transmitted in coordination from a first transmitting / receiving point and at least one other transmitting / receiving point; and reporting a phase offset, which is the phase difference of the first signal from a reference signal, at a timing determined based on first information relating to a phase change of the first signal transmitted from the first transmitting / receiving point.

[0013] Another aspect of the present disclosure is a program for causing a computer to synthesize at least two received signals transmitted in coordination from a first transmitting / receiving point and at least one other transmitting / receiving point, and to report a phase offset, which is the phase difference of the first signal from a reference signal, at a timing determined based on first information relating to a phase change of the first signal transmitted from the first transmitting / receiving point.

[0014] According to one aspect of this disclosure, a method, information processing device, user device, and program can be provided that can reduce the overhead caused by reporting phase offsets from a device that receives signals transmitted in coordination from multiple transmission and reception points.

[0015] Figure 1 is a diagram showing an example of the system configuration of a communication system. Figure 2 is a diagram illustrating the hardware configuration of a control device. Figure 3 is a diagram showing an example of the functional configuration of a control device. Figure 4 is an example of a flowchart of the reporting cycle determination process of a control device according to the first embodiment. Figure 5 is a diagram showing an example of a processing sequence related to the reporting of phase offset in a communication system. Figure 6 is a diagram showing another example of a processing sequence related to the reporting of phase offset in a communication system. Figure 7 is an example of a flowchart of the reporting cycle determination process of a control device according to a modified example of the first embodiment. Figure 8 is an example of a graph of the measurement results for each measurement of the phase rotation amount of the uplink SRS from the UE in one radio frame, measured at distributed station #n. Figure 9 is an example of a flowchart of the reporting cycle determination process of a control device according to the second embodiment. Figure 10 is an example of a flowchart of the reporting cycle update process of a control device according to the third embodiment. Figure 11 is a diagram showing an example of a processing sequence related to the reporting of phase offset in a communication system according to the third embodiment. Figure 12 is an example of the hardware configuration of a UE. Figure 13 is a diagram showing an example of the functional configuration of a UE according to the fourth embodiment. Figure 14 is an example of a flowchart of the phase offset reporting process of the UE according to the fourth embodiment. Figure 15 is a diagram showing an example of a sequence of processing related to the reporting of phase offset in the communication system according to the fourth embodiment.

[0016] One aspect of this disclosure is a method by which a computer performs the following: acquiring first information relating to a phase change of a first signal transmitted from a first transmitting / receiving point; and determining, based on the first information, the timing at which a first device reports a phase offset. The first transmitting / receiving point is a transmitting / receiving point that transmits a signal synthesized in the first device to the first device in coordination with at least one other transmitting / receiving point. The phase offset is the phase difference of the first signal from a reference signal in the first device. The first information is information that reflects at least one of the following: changes in the radio wave propagation environment; changes in the characteristics of the RF (Radio Frequency) circuits provided in the second transmitting / receiving point and the first device; and the influence of the stability of the carrier frequency at the second transmitting / receiving point.

[0017] The computer that performs this method is, for example, a computer that operates as a control device for controlling a base station, a base station and relay station that perform coordinated transmission, or a computer that operates as the first device. The first device is, for example, a terminal station and a relay station that receive signals transmitted by coordinated transmission. The terminal station is, for example, a mobile station of a user terminal such as a smartphone, tablet terminal, and in-vehicle device. However, it is not limited to this, and the terminal station may be a stationary terminal that does not move. The transmitting and receiving points include, for example, base stations and relay stations.

[0018] In one aspect of this disclosure, the timing for the first device to report the phase offset is determined based on first information that reflects at least one of the factors causing the phase offset, such as changes in the radio wave propagation environment, changes in the characteristics of the RF circuit provided in the first transmitting / receiving point and the first device, and the influence of the stability of the carrier frequency at the first transmitting / receiving point. As a result, the phase offset reports from the first device are made in accordance with changes in the phase offset, reducing the number or frequency of phase offset reports and reducing the overhead caused by the phase offset reports from the first device. Furthermore, in one aspect of this disclosure, it is also possible to prevent the number or frequency of phase offset reports from the first device from becoming too low, thereby preventing a reduction in the effect of improving the received signal power obtained by CJT.

[0019] In one aspect of this disclosure, the stability of the carrier frequency at a first transmitting / receiving point may be used as the first information. As the stability of the carrier frequency at the first transmitting / receiving point, for example, a required value defined in a predetermined specification for the stability of the oscillation frequency at the transmitting / receiving point, and an approximate value of the stability of the carrier frequency at the first transmitting / receiving point obtained based on measured values ​​of the phase rotation amount at at least two time points obtained from the signal transmitted or received at the first transmitting / receiving point, may be used. The predetermined specification is, for example, the 3GPP (Third Generation Partnership Project) specification and the IEEE 802.11 standard ac, etc. However, the specification defining the required value of the carrier frequency stability is not limited to this.

[0020] The computer may obtain a first phase deviation for the first signal from the carrier frequency and the stability of the carrier frequency at the first transmission / reception point, and determine the phase offset reporting period such that the second phase deviation for the first signal, which is permissible in signal synthesis in the first device, is less than or equal to the value obtained by dividing it by the first phase deviation. This makes it possible to determine the phase offset reporting period while taking into account the phase deviation caused by the stability of the carrier frequency at the first transmission / reception point. Therefore, this is more useful when the first device is, for example, a fixed-installation device or stationary device where there are few changes in the radio wave propagation environment and the characteristics of the RF circuit.

[0021] In one aspect of the present disclosure, the computer may acquire, as first information, a set of measured values ​​of phase rotation amounts obtained from a signal transmitted or received at the first transmitting / receiving point at multiple points in time within a first period that includes the period from the start of use of the frequency channel currently in use in communication between the first transmitting / receiving point and the first device to the present, and determine a phase offset reporting period based on the rate of phase change of the signal transmitted or received at the first transmitting / receiving point, as indicated by the set of measured values ​​of phase rotation amounts. More specifically, the computer may acquire, as information indicating the rate of phase change of the signal, a first value based on the time difference between two measured values ​​in each of one or more combinations of two measured values ​​from the set of measured values ​​of phase rotation amounts whose difference is greater than or equal to a threshold, and determine a phase offset reporting period such that the first value is less than or equal to the first value. The first period is, for example, the period of the immediately preceding one or more radio frames, the period of a predetermined number of immediately preceding subframes, the period of a predetermined number of immediately preceding slots, the transmission power or phase offset control period, etc. Furthermore, the first period may be the period of one or more wireless frames, the period of a predetermined number of subframes, the period of a predetermined number of slots, etc., prior to the immediately preceding predetermined period.

[0022] The set of measured phase rotation values ​​obtained from the signal transmitted or received at the first transmitting / receiving point is information that reflects the influence of changes in the radio wave propagation environment, changes in the characteristics of the RF circuit provided at the first transmitting / receiving point and the first device, and the stability of the carrier frequency at the first transmitting / receiving point. According to one aspect of this disclosure, the reporting period of the phase offset is determined taking into account changes in the radio wave propagation environment and changes in the characteristics of the RF circuit, and the first device can report the phase offset at an appropriate timing corresponding to the change in the phase offset. By compensating the phase based on the phase offset reported at a more appropriate timing, the signal transmitted from the first transmitting / receiving point will be in response to changes in the radio wave propagation environment and changes in the characteristics of the RF circuit, and sufficient gain can be obtained in the synthesis of the received signal in the first device. Furthermore, in determining the reporting period of the phase offset, the radio resources used are limited to those related to obtaining the measured phase rotation values ​​obtained from the signal transmitted or received at the first transmitting / receiving point, thus reducing the use of radio resources.

[0023] In one aspect of this disclosure, the computer may acquire, as first information, a predetermined number of phase offset values ​​in each of a predetermined number of subbands acquired by a first device, and determine a phase offset reporting period based on the change in the predetermined number of phase offset values ​​between the predetermined number of subbands. The computer may acquire a second value based on the predetermined number of phase offset values, acquire a third value based on the second value and a predetermined reporting period, and determine a phase offset reporting period such that it is less than or equal to the third value. The second value may be, for example, the average value of the predetermined number of phase offset values. The third value may be a value obtained by dividing the allowable phase offset by the second value and multiplying the result by a predetermined reporting period.

[0024] The predetermined number of phase offset values ​​in each of the predetermined number of subbands acquired by the first device are the phase offsets in the first device themselves, and therefore better reflect the influence of changes in the radio wave propagation environment, changes in the characteristics of the RF circuits provided at the first transmission / reception point and the first device, and the stability of the carrier frequency at the first transmission / reception point. By determining the phase offset reporting period based on the predetermined number of phase offset values ​​in each of the predetermined number of subbands acquired by the first device, the reporting period of the phase offset becomes a period corresponding to the change in the phase offset, and the phase offset is reported from the first device at a more appropriate timing. As a result, the phase is compensated based on the phase offset, so that the signal transmitted from the first transmission / reception point responds to changes in the radio wave propagation environment and changes in the characteristics of the RF circuits, and a higher gain can be obtained in the synthesis of the received signals in the first device.

[0025] In one aspect of this disclosure, the computer may be a first device. In this case, the computer may acquire a predetermined number of phase offset values ​​in each of a predetermined number of subbands as first information, use the first information to determine whether a predetermined condition regarding the phase offset value is met for a first transmission / reception point, and if the predetermined condition is met, decide to perform a phase offset report for the first transmission / reception point and send a request for the allocation of radio resources to be used for the report. The predetermined condition is, for example, that any of the predetermined number of phase offset values ​​in each of the predetermined number of subbands is greater than or equal to a predetermined threshold. However, the predetermined condition is not limited to this.

[0026] In one aspect of this disclosure, the first device can make the number or frequency of phase offset reports more suitable for changes in phase offset by determining the reporting of phase offsets for each of a predetermined number of subbands for a first transmission / reception point. This can further reduce the overhead caused by phase offset reporting from the first device.

[0027] Another aspect of the present disclosure can also be identified as an information processing device that performs the processing of the above method. The information processing device includes a control unit that performs: acquiring first information relating to a phase change of a first signal transmitted from a first transmitting / receiving point that transmits a signal synthesized in the first device to the first device in coordination with at least one other transmitting / receiving point; and determining, based on the first information, the timing at which the first device reports a phase offset, which is the phase difference of the first signal from a reference signal. The control unit is, for example, a processor such as a CPU (Central Processing Unit).

[0028] Another aspect of the present disclosure is a method by which user equipment (UE) combines at least two received signals transmitted in coordination from a first transmitting / receiving point and at least one other transmitting / receiving point, and reports a phase offset, which is the phase difference of the first signal from a reference signal, at a timing determined based on first information relating to a phase change of the first signal transmitted from the first transmitting / receiving point. Another aspect of the present disclosure can also be identified as a UE that performs the processing by the method. The UE comprises a control unit that combines at least two received signals transmitted in coordination from a first transmitting / receiving point and at least one other transmitting / receiving point, and reports a phase offset, which is the phase difference of the first signal from a reference signal, at a timing determined based on first information relating to a phase change of the first signal transmitted from the first transmitting / receiving point.

[0029] 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.

[0030] 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.

[0031] <Common Configuration of Embodiments> Figure 1 shows an example of the system configuration of the communication system 100. 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, for example, a wireless communication system of 5G, LTE (Long Term Evolution), and mobile communication methods of 5G 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.

[0032] 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 (RU#1 to #3) shown in Figure 1 are assumed to be located within the same communication area. Each distributed base station is connected to the control unit 1.

[0033] 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 its 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. Note that a distributed base station may have one antenna or multiple antennas.

[0034] 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 these, and UE 2 may be a stationary terminal device such as an IoT 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 small base stations, mobile base stations, in-vehicle devices, and smartphones. In the following embodiments, it is assumed that UE 2 has one antenna. However, it is not limited to these, and UE 2 may have multiple antennas.

[0035] In the example shown in Figure 1, distributed base station RU#1 contains transmission and reception points m_(0), m_(1), and m_(2), distributed base station RU#2 contains transmission and reception points m_(3) and m_(4), and distributed base station RU#3 contains transmission and reception points m_(5) and m_(6). Distributed base station RU#1 transmits three beams: b0, b1, and b2. Distributed base station RU#1 is also represented as the transmission and reception points m_(0), m_(1), and m_(2) of beams b0, b1, and b2. The string after the underscore or the string in parentheses is shown as a subscript in the figure. Distributed base station RU#2 transmits two beams: b3 and b4. Distributed base station RU#3 transmits two beams: b5 and b6. UE 2 uses the beam with the best communication quality from among beams b0-b6 to perform communication. UE 2 is an example of the "first device." Hereafter, distributed base stations will simply be referred to as "distributed stations."

[0036] Each distributed station (or transmitting / receiving point) and UE 2 are synchronized. The control device 1 allocates radio resources for the signals transmitted from each transmitting / receiving point so that the signals transmitted from each transmitting / receiving point arrive at UE 2 simultaneously. UE 2 receives notification from the control device 1 of the allocation of radio resources for the signals transmitted from each distributed station and receives the signals transmitted from each distributed station's transmitting / receiving point according to the configuration of those radio resources. The objective of CJT is for the signals transmitted from each distributed station's transmitting / receiving point with each beam pattern to arrive at UE 2 in phase. To achieve this, it is required that signals from each transmitting / receiving point be transmitted on a carrier wave with phase correction equal to the offset from the received signal from a reference transmitting / receiving point. The reference transmitting / receiving point is selected by the control device 1 from among a plurality of transmitting / receiving points that perform coordinated transmission to UE 2. Hereinafter, when referred to as "phase offset," it refers to the phase offset of the signal in question from the received signal from the reference transmitting / receiving point. Hereinafter, the signal from the reference transmitting / receiving point will be referred to as the reference signal.

[0037] The phase offset of a signal from a single transmission / reception point is measured by UE 2 using a measurement signal from that transmission / reception point and reported to the control device 1. In the first embodiment, UE 2 divides the channel bandwidth into a plurality of subbands and obtains a phase offset value for each subband. For each subband, UE 2 measures the amount of phase rotation between the target signal and the reference signal, and obtains the phase offset value of the target signal by subtracting the amount of phase rotation of the reference signal from the amount of phase rotation of the target signal.

[0038] For measuring phase offset, signals such as CSI-RS (Channel State Information - Reference Signal), a signal for measuring phase offset, or a data signal can be used. One or more CSI-RS signals are placed in one resource block. Therefore, CSI-RS signals are transmitted at a frequency of at least the same duration as one slot. For example, if the subcarrier interval is 30 kHz, one slot is 0.5 milliseconds, so in this case, CSI-RS signals are transmitted at a frequency of 0.5 milliseconds or less. Each time UE 2 receives a CSI-RS signal from each transmission / reception point, it measures the phase rotation amount for the signal from each point and obtains the phase offset value. However, reporting the phase offset every time UE 2 receives a CSI-RS signal can be excessive and increase overhead. On the other hand, if the frequency or number of phase offset reports from UE 2 is reduced too much, the phase offset compensation for the signals transmitted from each transmission / reception point may not be properly performed, and the effect of CJT improving the received signal power may be reduced.

[0039] A change in phase offset occurs due to a change in the phase of the signal. This change in phase can be caused by factors such as changes in the radio wave propagation environment, changes in the characteristics of the RF (Radio Frequency) circuits in each distributed station and UE2, and the stability of the carrier frequency at each distributed station. One factor influencing changes in the radio wave propagation environment is, for example, the arrival conditions of reflected waves. Factors influencing changes in the characteristics of the RF circuits include, for example, temperature and humidity.

[0040] Therefore, since the phase offset change is caused by a change in the signal phase, by setting the timing at which UE 2 reports the phase offset to correspond to the change in the signal phase, it is possible to reduce overhead and obtain sufficient gain of the received signal by the CJT at the same time. In this disclosure, the "timing at which UE 2 reports the phase offset" includes, for example, the reporting period, frequency, and number of times.

[0041] In each embodiment of this disclosure, the overhead caused by reporting the phase offset from UE 2 is reduced by determining the timing at which UE 2 reports the phase offset according to the change in the phase of the signal. The following embodiments differ in how they capture the change in the phase of the signal. In the first embodiment, the timing of reporting the phase offset is determined based on the stability of the oscillation frequency. In the second embodiment, the timing of reporting the phase offset is determined based on the speed of the phase change. In the third and fourth embodiments, the timing of reporting the phase offset is determined based on the measurement result of the phase offset value in UE 2. The difference in the third embodiment is that the control device 1 determines the timing of reporting the phase offset, while in the fourth embodiment, UE 2 determines the reporting timing. In the following embodiments, for the sake of simplicity of explanation, it is assumed that the distributed station is equipped with one transmitting / receiving point. However, even if the distributed station is equipped with multiple transmitting / receiving points, the embodiments can be applied by replacing the distributed station with a transmitting / receiving point.

[0042] <First Embodiment> In the first embodiment, the control device 1 determines the reporting period of the phase offset of UE 2 using the required value for oscillation frequency stability specified in the 3GPP (Third Generation Partnership Project) specifications as the stability of the oscillation frequency in the distributed station. The required value for carrier frequency stability specified in the 3GPP specifications is ±50 ppb (parts per billion) or less.

[0043] FIG. 2 is a diagram illustrating the hardware configuration of the control device 1. The control device 1 includes a CPU 101, a main storage device 102, an external storage device 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 have a multiprocessor configuration. In addition to the CPU 101, a Graphics Processing Unit (GPU), a Digital Signal Processor (DSP), etc. may be provided. Further, the CPU 101 may cooperate with a hardware circuit such as a Field Programmable Gate Array (FPGA).

[0044] The CPU 101 executes a computer program developed executable in the main storage device 102 and provides the processing of the control device 1. The main storage device 102 stores the computer program executed by the CPU 101, the data processed by the CPU 101, etc. The main storage device 102 is a Dynamic Random Access Memory (DRAM), a Static Random Access Memory (SRAM), a Read Only Memory (ROM), etc. Further, the external storage device 103 is used, for example, as a storage area that supplements the main storage device 102, and stores the computer program executed by the CPU 101, the data processed by the CPU 101, etc. The external storage device 103 is a hard disk drive, a Solid State Drive (SSD), etc. Further, a drive device for a removable storage medium may be connected to the control device 1. The removable storage medium is, for example, a Blu-ray Disc, a Digital Versatile Disc (DVD), a Compact Disc (CD), a flash memory card, etc. The CPU 101 is an example of the "control unit" of the "information processing device".

[0045] The communication device 104 communicates with an external network such as a distributed base station and the Internet via, for example, an 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 a "computer" and an "information processing device". Note that the hardware configuration of the control device 1 is not limited to that shown in FIG. 2.

[0046] FIG. 3 is a diagram showing an example of the functional configuration of the control device 1. The control device 1 includes a control unit 11 as a functional configuration. The functions of the control unit 11 are achieved by the CPU 101 executing a predetermined program.

[0047] The control unit 11 controls the CJT. More specifically, the control unit 11 selects a distributed station that performs coordinated transmission to the UE 2, determines the reporting period of the phase offset of the UE 2, allocates radio resources for phase offset measurement, allocates radio resources for reporting of the UE 2, and performs phase offset compensation and the like.

[0048] The control unit 11 obtains the reporting period of the phase offset of the UE 2 from the stability of the oscillation frequency. More specifically, the control unit 11 first obtains the phase deviation σ_(φ) of the signal transmitted from the distributed station from the stability p of the oscillation frequency and the carrier frequency f_(c) according to the following formula (1). Note that the characters in parentheses following the underscore are shown as subscripts in the formula and the figure.

[0049] The phase deviation σ_(φ) (unit: rad / s) is the amount of phase rotation that deviates in one second. That is, the phase deviation is information indicating the change in the phase of the signal. In the first embodiment, as the stability p of the oscillation frequency, ±50 ppb (parts per billion), which is the required value defined by the 3GPP specification, is used.

[0050] On the other hand, in the communication system 100, the loss gain L_(CJT) (dB) when combining multiple received signals, which is permissible in CJT, and the corresponding permissible value of the phase measurement error permissible in UE 2 are predetermined. The permissible value of the phase measurement error permissible in UE 2 can also be called the permissible phase deviation φ_(REF) (unit: rad / s). For example, if the permissible loss L_(CJT) during combination is 3 dB, then the permissible phase deviation φ_(REF) is 33 (degrees). If a phase shift of up to φ_(REF) per second is permissible, then it can be considered that a change in the phase offset value is also permissible within the time width in which a phase shift of the phase deviation σ_(REF) is permissible. That is, the reporting period T_(Φ) of the phase offset in UE 2 can be expressed by the following equation 2.

[0051] The control unit 11 determines the reporting period T_(Φ) to satisfy Equation 2, taking into account the configuration of the wireless frame. For example, the control unit 11 determines the reporting period T_(Φ) to be the largest value among the multiples of the transmission period of the CSI-RS, which is a signal for measuring the phase offset, that satisfies Equation 2. In the first embodiment, a value common to all distributed stations is used as the stability of the oscillation frequency, so the reporting period T_(Φ) can be determined for all distributed stations.

[0052] The control unit 11 allocates (schedules) wireless resources (resource blocks) for reporting by UE 2 at intervals of the determined reporting period T_(Φ) on the uplink control channel so that phase offset reports are made at intervals of the determined reporting period T_(Φ). The control unit 11 notifies UE 2 of the allocation of wireless resources for reporting. UE 2 then reports the phase offset according to the allocation of wireless resources, so that phase offset reports are made at the determined reporting period T_(Φ).

[0053] Figure 4 is an example of a flowchart of the reporting cycle determination process of the control device 1 according to the first embodiment. The process shown in Figure 4 is performed, for example, after the distributed station selection process has been executed and completed. The distributed station selection process is performed, for example, each time a radio frame is started, and when it is determined that a re-selection of the distributed station is necessary based on the received signal power reported from the UE 2. The main entity executing the process shown in Figure 4 is the CPU 101 of the control device 1, but for convenience, the functional components will be described as the main components. The same applies to the flowcharts following Figure 4.

[0054] In OP11, the control unit 11 obtains the phase deviation σ_(φ) according to Equation 1, using the carrier frequency stability of ±50 ppb and the carrier frequency as defined in the 3GPP specification. In OP12, the control unit 11 obtains the allowable phase deviation φ_(REQ). The allowable phase deviation φ_(REQ) may be pre-stored in, for example, an external storage device 103. In OP13, the reporting period T_(Φ) of the phase offset is set considering the configuration of the wireless frame so as to satisfy Equation 2. After that, the process shown in Figure 4 is completed.

[0055] Figure 5 shows an example of a processing sequence related to the reporting of phase offset in the communication system 100. In Figure 5, the control device 1 and UE 2 of the communication system 100 are shown separately. Figure 5 shows the sequence when the allocation of wireless resources for the signal used to measure the phase offset and the allocation of wireless resources for reporting the phase offset by UE 2 occur at the same time. Communication between the control device 1 and UE 2 is performed using a control channel.

[0056] In S11, the control device 1 selects distributed stations to perform coordinated transmission to UE 2. In the selection of distributed stations in S11, the number of distributed stations to perform coordinated transmission to UE 2 and a reference distributed station are also selected. The method for selecting distributed stations to perform coordinated transmission to UE 2 and the method for selecting the reference distributed station are not limited to a specific method. Hereinafter, the reference distributed station will be referred to as the reference station. Also, hereafter, when referring to a distributed station, it will refer to a distributed station other than the reference station.

[0057] In S12, the control device 1 performs, for example, the reporting period determination process shown in Figure 4, and determines the reporting period T_(Φ) for the phase offset of UE 2. In S13, the control device 1 allocates radio resources for phase offset measurement to the reference station and at least one distributed station determined in S11, and also allocates radio resources for reporting UE 2. In the allocation of radio resources for phase offset measurement, for example, the placement of CSI-RS is determined in the downlink slots. Since CSI-RS is transmitted in each downlink slot, the placement will be the same in all subsequent downlink slots until the resources are reallocated.

[0058] In S14, the control device 1 notifies UE 2 of the reference station and at least one distributed station selected in S11, the allocation of radio resources for phase offset measurement, and the allocation of radio resources for UE 2's reporting. The control device 1 also notifies the reference station and each distributed station of the same information. As a result, the reference station and each distributed station transmit signals for phase offset measurement via downlink for each slot using the instructed radio resources.

[0059] In S15, UE 2 receives phase offset measurement signals from the base station and each distributed station according to the notified allocation of radio resources for phase offset measurement, and measures the phase offset value from the received signal from the base station (reference signal) for each predetermined number of subbands for the received signal from each distributed station. The phase offset measurement process in S15 is performed each time a phase offset measurement signal is received from the base station and each distributed station.

[0060] In S16, UE 2, at the time when the reporting period T_(Φ) has elapsed, uses the reporting radio resource notified in S14 to report the latest phase offset measurement results for each distributed station to the control device 1.

[0061] In S17, the control device 1 performs phase offset compensation for each distributed station other than the base station based on the phase offset measurement results received from UE 2. In phase offset compensation, the control device 1 calculates the phase correction value for each subband of the carrier wave for each distributed station and notifies the phase correction value for each subband. Alternatively, the control device 1 may calculate the phase correction value for each subband of the carrier wave for each distributed station, perform phase correction of the carrier wave based on the phase correction value for each subband, and notify information about the carrier wave after phase correction. The phase correction value for each subband may be obtained, for example, as a 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. As a result, the distributed stations transmit using a carrier wave whose phase has been shifted and corrected by the notified phase correction value in each subband of the carrier wave frequency. Thereafter, for example, until the selection of a distributed station is performed again, the reporting of the phase offset from UE 2 in S16 and the distribution station and phase offset compensation in S17 are repeatedly performed according to the phase offset reporting period T_(Φ) determined in S12.

[0062] Figure 6 shows another example of the processing sequence related to reporting the phase offset in the communication system 100. In Figure 6, as in Figure 5, the control device 1 and UE 2 of the communication system 100 are shown separately. Figure 6 shows the sequence when the allocation of radio resources for the signal used to measure the phase offset and the allocation of radio resources for reporting the phase offset by UE 2 are performed separately.

[0063] In S21, the control device 1 selects the distributed stations, similar to S11. In S22, the control device 1 allocates radio resources for phase offset measurement. In S23, the control device 1 determines the reporting period T_(Φ) for the phase offset of UE 2, similar to S12. In S24, the control device 1 allocates radio resources for reporting UE 2.

[0064] In S25, the control device 1 notifies UE 2, the reference station, and at least one distributed station of the allocation of radio resources for phase offset measurement and the allocation of radio resources for reporting by UE 2, similar to S14.

[0065] In steps S26 to S28, similar to steps S15 to S17, UE 2 measures the phase offset (S26), and when the reporting period T_(Φ) has elapsed, it reports the phase offset measurement results according to the allocation of radio resources for reporting (S27), and the control device 1 performs phase offset compensation for each distributed station (S28).

[0066] In the first embodiment, the control device 1 determines the phase offset reporting period for UE 2 using the required value for oscillation frequency stability specified in the 3GPP specification as the stability of the oscillation frequency at the distributed stations. This makes it possible to set the phase offset reporting period for UE 2 to a value corresponding to the stability of the oscillation frequency at the distributed stations, thereby reducing the overhead of phase offset reporting by UE 2. Furthermore, determining the phase offset reporting period for UE 2 based on the stability of the oscillation frequency at the distributed stations is more effective in environments where there are few changes in the radio wave propagation environment and the characteristics of the RF circuits equipped in each distributed station and UE 2. An environment where there are few changes in the radio wave propagation environment and the characteristics of the RF circuits equipped in each distributed station and UE 2 is, for example, a state in which UE 2 is almost stationary, such as when IoT devices are fixedly installed.

[0067] Furthermore, according to the first embodiment, the determination of the phase offset reporting period for UE 2 can be performed by the control device 1 alone, without using information from UE 2 or distributed stations, for example, thus suppressing the occurrence of overhead in determining the phase offset reporting period. In the first embodiment, even if UE 2 is equipped with multiple antennas, the phase offset reporting period can be determined in the same manner as described above.

[0068] <Modification of the First Embodiment> In the first embodiment, the required value for oscillation frequency stability specified in the 3GPP specification is used as the oscillation frequency stability in the distributed station. Instead, in the modification of the first embodiment, an approximate value for the oscillation frequency stability in the distributed station is obtained from the amount of phase rotation in the distributed station, which is acquired using two uplink reference signals transmitted from UE 2 within the same slot, and used. The system configuration and the hardware and functional configuration of the control device 1 are the same as in the first embodiment. The uplink reference signal used in this modification is, for example, SRS (Sounding Reference Signal).

[0069] Figure 7 is an example of a flowchart of the reporting cycle determination process of the control device 1 according to a modified example of the first embodiment. The process shown in Figure 7 may be executed in place of the reporting cycle determination process in Figure 5 or Figure 6 (S12 in Figure 5, S23 in Figure 6) in the first embodiment, for example. The process shown in Figure 7 is executed for each distributed station other than the base station. In Figure 7, the target distributed station is denoted as distributed station #n using the variable n. When the number of distributed stations including the base station is N, n can take values ​​from 1 to N-1. Distributed station #0 represents the base station.

[0070] In OP21, the control unit 11 arranges two SRSs in the same uplink slot with a time interval ΔT_(SRS) to allocate wireless resources for phase rotation measurement. In OP22, the control unit 11 notifies UE 2 of the allocation of wireless resources for phase rotation measurement. Subsequently, UE 2 transmits SRSs according to the allocation of wireless resources for phase rotation measurement.

[0071] In OP23, the control unit 11 obtains the phase rotation amounts of two SRS signals transmitted from UE 2 and received by distributed station #n at a time interval ΔT_(SRS). The phase rotation amount obtained from the SRS received first at the time interval ΔT_(SRS) is denoted as φ_(n,0). The phase rotation amount obtained from the SRS received second at the time interval ΔT_(SRS) is denoted as φ_(n,1). In OP24, the control unit 11 calculates an approximate value p^_(n) of the carrier frequency stability at distributed station #n from the following equation 3. "^" is a symbol indicating that it is an approximation.

[0072] The phase rotation amount reflects the influence of changes in the radio wave propagation environment, changes in the characteristics of the RF circuits of the distributed station and UE 2, and the stability of the carrier frequency. Here, by assuming that the changes in the radio wave propagation environment and the changes in the characteristics of the RF circuits of the distributed station and UE 2 are constant in the time interval ΔT_(SRS) (<1 slot time length), the difference between the phase rotation amount φ_(n,0) and the phase rotation amount φ_(n,1) can be considered to reflect the influence of the stability of the carrier frequency. Thus, an approximate value of the carrier frequency stability at distributed station #n can be obtained, as shown in equation 3 above.

[0073] In OP25, the control unit 11 obtains the allowable phase deviation φ_(REF). In OP26, the phase offset reporting period T_(Φn) is set considering the configuration of the wireless frame so as to satisfy Equation 4 below. After that, the process shown in Figure 7 is completed.

[0074] In a modified version of the first embodiment, a phase offset reporting period T_(Φn) is obtained for each distributed station. The control unit 11 may allocate radio resources for reporting so that the phase offset is reported to each distributed station according to the reporting period T_(Φn), so that the phase offset is reported to the UE 2 at different timings for each distributed station. In this case, the processes S16 and S17 in the sequence of Figure 5, and the processes S27 and S28 in the sequence of Figure 6 are performed individually according to the reporting period T_(Φn) for each distributed station.

[0075] Alternatively, the control unit 11 may, for example, use the minimum value among the reporting periods T_(Φn) of each distributed station as the common reporting period T_(Φ) for all distributed stations, and based on the reporting period T_(Φ), allocate radio resources for reporting as in the first embodiment, so that the phase offset for all distributed stations is reported to the UE 2 collectively with the reporting period T_(Φ).

[0076] In a modified version of the first embodiment, for each distributed station other than the base station, an approximate value of the carrier frequency stability is obtained based on the amount of phase rotation obtained from the SRS from UE 2, and the reporting period T_(Φn) of the phase offset is determined using this approximate value. This makes it possible to set the reporting period T_(Φn) for each distributed station to a value corresponding to the phase change due to the influence of the carrier frequency stability of each distributed station, thereby reducing the overhead of reporting the phase offset and obtaining a greater effect of CJT through carrier frequency phase offset compensation.

[0077] Furthermore, three or more SRSs for the uplink from UE 2 may be arranged in the same slot, and the control device 1 may determine an approximate value p^ of the stability of the carrier frequency of the distributed station based on the phase rotation amount of the three or more SRSs. In this case, the approximate value p^ of the stability of the carrier frequency of the distributed station may be determined, for example, by linear approximation.

[0078] In the modified version of the first embodiment, it is sufficient to obtain an approximate value of the stability of the carrier frequency of the distributed station, so even if UE 2 is equipped with multiple antennas, the SRS from any of the antennas may be used. Therefore, if UE 2 is equipped with multiple antennas, by selecting one antenna to use, an approximate value of the stability of the carrier frequency of the distributed station can be obtained in the same manner as in the second embodiment. Furthermore, although not limited to this, an approximate value of the stability of the carrier frequency of the distributed station may be obtained for each antenna equipped on UE 2 in the same manner as in the second embodiment, and for example, the average value may be used to determine the reporting period T_(Φn) of the phase offset.

[0079] As another variation of the first embodiment, the control device 1 may notify the UE 2 of the reporting period T_(Φn) determined for each distributed station, and the UE 2 may, for each distributed station, send a request to the control device 1 for the allocation of radio resources for reporting at each reporting period T_(Φn), receive the allocation of radio resources for reporting, and report the phase offset. As another variation of the first embodiment, the UE 2 may determine the reporting period T_(Φ) in the same manner as the control device 1 in the first embodiment or a variation thereof, send a request to the control device 1 for the allocation of radio resources for reporting at each reporting period T_(Φ), receive the allocation of radio resources for reporting, and report the phase offset.

[0080] <Second Embodiment> In the second embodiment, the control device 1 determines the reporting period of the phase offset based on the rate of phase change. In the second embodiment, the rate of phase change is obtained for distributed station #n based on a set of measured values ​​of the amount of phase rotation obtained from the uplink SRS transmitted from UE 2, measured K times at equal intervals in the preceding radio frame, φ_(n) = {φ_(n,0), φ_(n,1), ..., φ_(n,K-1)}. In the second embodiment, explanations common to the first embodiment are omitted. In the second embodiment, the system configuration and the hardware configuration and functional configuration of the control device 1 are the same as in the first embodiment.

[0081] Figure 8 is an example graph showing the measurement results for each measurement of the phase rotation amount of the uplink SRS from UE 2 in one radio frame, measured at distributed station #n. The phase rotation amount is measured K times in one radio frame at a predetermined period. Let φ_(n,k) be the phase rotation amount of the kth measurement in one radio frame at distributed station #n. The variable k, which indicates the measurement number, can take values ​​from 0 to K-1.

[0082] In the second embodiment, the control unit 11 identifies one or more combinations of two measured values ​​in which the difference in phase rotation amount |φ_(n, k + δ) - φ_(n, k)| is greater than or equal to a threshold φ_(TH). The control unit 11 finds the minimum value δ_(n) of the time difference between the two measured values ​​from the one or more combinations, and determines the reporting period T_(Φn) of the phase offset for distributed station #n, taking into account the configuration of the radio frame, such that it is less than or equal to δ_(n).

[0083] In the example shown in Figure 8, the combinations of two measured values ​​for which the difference in phase rotation amount is greater than or equal to the threshold φ_(TH) are φ_(n, k0) and φ_(n, k0 + δ_(k0)), φ_(n, k1) and φ_(n, k1 + δ_(k1)), and φ_(n, k2) and φ_(n, k2 + δ_(k2)). Of these, δ_(n) with the smallest time difference is δ_(n, k2) which is the time difference between the measured values ​​of phase rotation amount φ_(n, k2) and φ_(n, k2 + δ_(k2)).

[0084] The interval between two measured values ​​where the difference in phase rotation amount is greater than or equal to the threshold φ_(TH) and the time difference is smallest is the interval in the radio frame in which the phase rotation amount changed by more than or equal to the threshold φ_(TH) in the shortest amount of time. In other words, it can be said to be the interval in which the change in phase rotation amount is fastest. By setting the phase offset reporting period T_(Φn) for distributed station #n to be less than or equal to the time length δ_(n) of the interval, UE 2 can measure the phase offset at intervals corresponding to the change in phase rotation amount. Furthermore, if radio resources are allocated so that data communication can be performed periodically for data communication to which CJT is applied, the minimum value of the phase offset reporting period T_(Φn) for distributed station #n may be set to the period of the data communication so that phase offset compensation is performed at least before the implementation of the data communication.

[0085] Figure 9 is an example of a flowchart of the reporting cycle determination process of the control device 1 according to the second embodiment. The process shown in Figure 9 is, for example, a process that is executed in the second embodiment instead of the reporting cycle determination process in Figure 5 or Figure 6 in the first embodiment (S12 in Figure 5, S23 in Figure 6). The process shown in Figure 9 is executed for each distributed station other than the base station.

[0086] In OP31, the control unit 11 acquires a set of measured phase rotation values ​​φ_(n) = {φ_(n,0), φ_(n,1), ..., φ_(n,K-1)} obtained from the uplink SRS transmitted from UE 2 in the immediately preceding wireless frame for distributed station #n. These measured phase rotation values ​​are, for example, held in the main memory 102 of the control device 1 for a predetermined period of time after acquisition.

[0087] In OP32, the control unit 11 identifies combinations of two measured values ​​included in the set of measured values ​​for phase rotation amount φ_(n) such that the difference in phase rotation amount is greater than or equal to the threshold value φ_(TH). The control unit 11 obtains δ_(n), which is the minimum of the time differences between the two measured values ​​for each identified combination. In OP33, the control unit 11 sets the reporting period T_(Φn) for the phase offset for UE 2 so that it is less than or equal to δ_(n). After that, the process shown in Figure 9 is completed.

[0088] The sequence of processing related to the reporting of phase offset in the communication system 100 according to the second embodiment is the same as in Figure 5 or Figure 6 in the first embodiment, except that the process for determining the phase offset reporting period is replaced by the process shown in Figure 9. In the second embodiment, the phase offset reporting period T_(Φn) is determined for each distributed station. Therefore, when a reporting period T_(Φn) is used for each distributed station, the processes S16 and S17 in the sequence of Figure 5, and the processes S27 and S28 in the sequence of Figure 6 are performed individually according to the reporting period T_(Φn) for each distributed station. However, this is not limited to this, and for example, the minimum value among the reporting periods T_(Φn) of each distributed station may be used as the reporting period T_(Φ) common to all distributed stations. In this case, the sequence of processing related to the reporting of phase offset in Figure 5 or Figure 6 is performed in the same manner as in the first embodiment.

[0089] In the second embodiment, the rate of phase change is determined from the set of measured values ​​of the phase rotation amount in the immediately preceding wireless frame, and the phase offset reporting period is set based on the rate of phase change. The phase rotation amount reflects the influence of changes in the radio wave propagation environment, changes in the characteristics of the RF circuits provided by the distributed station and UE 2, and the stability of the carrier frequency at the distributed station. Therefore, according to the second embodiment, the phase offset reporting period T_(Φn) can be determined to a value that is more suitable for the actual change in phase offset, taking into account the influence of changes in the radio wave propagation environment, changes in the characteristics of the RF circuits provided by the distributed station and UE 2, and the stability of the carrier frequency at the distributed station. Furthermore, since no communication with UE 2, such as reporting of the phase offset from UE 2, occurs when determining the phase offset reporting period T_(Φn), the use of wireless resources can be reduced. Therefore, the method for determining the phase offset reporting period T_(Φn) described in the second embodiment is more effective when it is desired to obtain a sufficient gain of the received signal by CJT with less use of wireless resources, even when UE 2 is moving.

[0090] In the second embodiment, a set of measured phase rotation values ​​obtained from the SRS of the uplink from UE 2 in the immediately preceding radio frame is used. Alternatively, a set of measured phase rotation values ​​obtained from the SRS of the uplink from UE 2 in the immediately preceding transmission power or phase offset control period at distributed station #n may be used. In the second embodiment, a set of measured phase rotation values ​​obtained from the SRS of the uplink from UE 2 in the immediately preceding radio frame is used. Alternatively, a set of measured phase rotation values ​​reported by the CSI-RS of the downlink from UE 2 in the immediately preceding radio frame may be used. Furthermore, the set of measured phase rotation values ​​obtained from the SRS of the uplink from UE 2 is not limited to the set of measured phase rotation values ​​obtained from the SRS of the uplink from UE 2 in the period of the immediately preceding radio frame, etc. Any set of measured phase rotation values ​​obtained from the SRS of the uplink from UE 2 in any period from the start of use of the currently used frequency channel in communication between UE 2 and the distributed station to the present may be used. For example, if the frequency channel currently in use in communication between UE 2 and the distributed station has not changed, a set of measured phase rotation values ​​obtained from the uplink SRS from UE 2 during a period of two or more previous radio frames may be used.

[0091] In the second embodiment, a set of measured values ​​of phase rotation amounts obtained from an SRS transmitted in one resource block of the uplink is used. Alternatively, multiple sets of measured values ​​of phase rotation amounts obtained from multiple SRSs transmitted in multiple resource blocks of the uplink may be used. In this case, for each set of measured values ​​of phase rotation amounts, the minimum value δ of the time difference between two measured values ​​whose phase rotation difference is greater than or equal to the threshold φ_(TH) may be found, and the average value or minimum value of the minimum value δ for each set may be found as δ_(n).

[0092] As another variation of the second embodiment, the control device 1 may notify the UE 2 of the reporting period T_(Φn) determined for each distributed station, and the UE 2 may, for each distributed station, send a request to the control device 1 for the allocation of radio resources for reporting at each reporting period T_(Φn), receive the allocation of radio resources for reporting, and report the phase offset. As another variation of the second embodiment, the UE 2 may, in the same manner as the control device 1 in the second embodiment, determine the reporting period T_(Φn) for the phase offset for each distributed station based on a set of measured values ​​of the CSI-RS phase rotation amount from each distributed station at a certain timing, send a request to the control device 1 for the allocation of radio resources for reporting at each reporting period T_(Φn), receive the allocation of radio resources for reporting, and report the phase offset.

[0093] In the second embodiment, if the UE 2 has multiple antennas, the control device 1 may select a reference antenna and determine the reporting period T_(Φn) using a set of measured values ​​of phase rotation amounts obtained from the SRS received from the reference antenna. The reference antenna may be determined by the control device 1 when calculating the reporting period T_(Φn). For example, the antenna with the highest average SNR for each distributed station may be selected as the reference antenna. Alternatively, if the UE 2 has multiple antennas, the control device 1 may obtain a set of measured values ​​of phase rotation amounts for the SRS received from each antenna, and for each set of measured values ​​of phase rotation amounts for each antenna, it may find the minimum value δ of the time difference between two measured values ​​whose phase rotation difference is greater than or equal to a threshold φ_(TH), and determine the average or minimum value of the minimum value δ for each set as δ_(n).

[0094] <Third Embodiment> In the third embodiment, the control device 1 updates the phase offset reporting period T_(Φn) based on the measurement result of the phase offset in UE 2. In the third embodiment, explanations common to the first embodiment are omitted. In the third embodiment, the system configuration and the hardware configuration and functional configuration of the control device 1 are the same as in the first embodiment.

[0095] In the third embodiment, the control unit 11 of the control device 1 receives a report from UE 2 of the phase offset acquired using downlink CSI-RS, performed according to the reporting period T_(Φn) for each distributed station. The set of phase offset values ​​at timing k in distributed station #n is denoted as Φ_(n,k) = {Φ_(n,0,k), Φ_(n,1,k), ..., Φ_(n,N_(SB)-1,k)}. N_(SB) is the subband number. Φ_(n,n_(SB),k) is the phase offset value in subband n_(SB), where Φ_(n,n_(SB),k) = φ_(n,n_(SB),k) - φ_(n_(ref),n_(SB),k). n_(SB) is a variable indicating the subband number. n_(SB) can take values ​​from 0 to N_(SB)-1. n_(ref) indicates the reference station.

[0096] The control unit 11 calculates the average value μ_(n,k) of the phase offset values ​​of each subband at timing k for distributed station #n, as shown in equation 5 below.

[0097] The control unit 11 updates the reporting period T_(Φn) according to the wireless frame configuration so that the following equation 6 is satisfied. T_(Φn_cut) is the current reporting period T_(Φn). T_(Φn_new) is the updated reporting period T_(Φn). Δ_Φ is the allowable value of the loss gain of the received signal due to CJT in UE 2 and the allowable value of the phase offset according to the transmit / receive point. For example, if the number of transmit / receive points is 4, the allowable value of the phase offset Δ_Φ is 32 degrees.

[0098] The control unit 11 determines the initial value T_(Φn_ini) of the reporting period T_(Φn) for distributed station #n, for example, on a slot-by-slot, radio frame-by-frame, or communication data-by-period basis. The initial value T_(Φn_ini) of the reporting period may be determined by the method described in the first or second embodiment, for example, or a predetermined value set in advance may be used. Furthermore, the initial value T_(Φn_ini) of the reporting period may differ for each distributed station, or it may be common to all distributed stations.

[0099] Figure 10 is an example of a flowchart of the report cycle update process of the control device 1 according to the third embodiment. The process shown in Figure 10 starts, for example, after the determination of the initial value T_(Φn_ini) of the report cycle and ends when the timing for determining the initial value T_(Φn_ini) of the report cycle is reached. The timing for determining the initial value T_(Φn_ini) of the report cycle is, for example, the execution of the selection of a distributed station and the start of a radio frame. The process shown in Figure 10 is executed for each distributed station other than the base station.

[0100] In OP41, the control unit 11 determines whether or not it has received a set of phase offset values ​​Φ_(n,k) at timing k in distributed station #n as a report from UE 2. If the set of phase offset values ​​Φ_(n,k) at timing k in distributed station #n has been received from UE 2 (OP41: YES), the process proceeds to OP42. If the set of phase offset values ​​Φ_(n,k) has not been received (OP41: NO), the process shown in Figure 10 ends.

[0101] In OP42, the control unit 11 calculates the average of the phase offset values ​​Φ_(n, n_(SB), k) included in the set of phase offset values ​​Φ_(n, k) using equation 5 above. In OP43, the control unit 11 sets the reporting period T_(Φn) considering the wireless frame configuration so as to satisfy equation 6 above. After that, the process shown in Figure 10 is completed.

[0102] Figure 11 is a diagram showing an example of a processing sequence related to the reporting of phase offset in the communication system 100 according to the third embodiment. In Figure 11, the control device 1 and UE 2 of the communication system 100 are shown separately. In the third embodiment, the reporting period T_(Φn) of the phase offset is updated individually for each distributed station other than the base station. Therefore, in Figure 11, the allocation of radio resources for the signal used to measure the phase offset and the allocation of radio resources for reporting the phase offset of UE 2 are performed individually. Communication between the control device 1 and UE 2 is performed using a control channel.

[0103] In S31, the control device 1 selects the distributed stations to perform coordinated transmission to UE 2 and the base station. In S32, the control device 1 allocates radio resources for phase offset measurement to the base station and distributed stations determined in S31. In S33, the control device 1 determines the initial value T_(Φn_ini) of the phase offset reporting period for UE 2.

[0104] In S34, the control device 1 allocates radio resources for reporting to UE 2 based on the phase offset reporting period T_(Φn) (initial value T_(Φn_ini)). In S35, the control device 1 notifies UE 2 of the allocation of radio resources for phase offset measurement and radio resources for reporting selected in S31, as well as the reference station and at least one distributed station selected in S31. The control device 1 also notifies the reference station and each distributed station of the allocation of radio resources for phase offset measurement and radio resources for reporting to UE 2.

[0105] In S36, UE 2 receives signals for phase offset measurement from the base station and each distributed station, and measures the phase offset from the received signal from the base station (reference signal) for each predetermined number of subbands of the received signal from each distributed station.

[0106] The processing from S37 onward is performed individually for each distributed station. For the sake of simplicity, the following explanation will focus on distributed station #n as an example, but similar processing is performed for other distributed stations. In S37, UE 2 reports the measurement result of the phase offset value of the received signal to control device 1 for distributed station #n, using the reporting radio resource notified in S35, at the timing when the phase offset reporting period T_(Φn) has elapsed. In S38, control device 1 performs phase offset compensation for distributed station #n based on the measurement result of the phase offset value received from UE 2.

[0107] In S39, the control device 1 updates the reporting period T_(Φn) for distributed station #n by executing the reporting period update process shown in Figure 10 based on the set of phase offset values ​​reported from UE 2 in S37. Subsequently, the same processing as in S34 and later is performed according to the updated reporting period T_(Φn). However, in the processing in S35, which occurs after the processing in S39, the allocation of radio resources for reporting from UE 2 is notified.

[0108] In the third embodiment, the phase offset reporting period T_(Φn) is updated using the set of phase offset values ​​reported from UE 2, so that the phase offset reporting period T_(Φn) can be set to a value that is more suitable for the actual change in phase offset value. As a result, the gain of the received signal by CJT can be obtained with less loss in UE 2.

[0109] As a modification of the third embodiment, UE 2 may update the phase offset reporting period T_(Φn) for each distributed station based on a set of phase offset values, in the same manner as the control device 1 in the third embodiment, and send a request to the control device 1 for the allocation of radio resources for reporting at each reporting period T_(Φn), receive the allocation of radio resources for reporting, and report the phase offset. In this case, the initial value of the reporting period T_(Φn_ini) may be notified to UE 2 from the control device 1, or it may be calculated by UE 2 using the method for determining the reporting period T_(Φn) in the first or second embodiment.

[0110] In the third embodiment, if the UE 2 has multiple antennas, the control device 1 may select a reference antenna and notify the UE 2 of the reference antenna, and the UE 2 may report to the control device 1 a set of phase offset values ​​measured from the CSI-RS received by the reference antenna (S35 to S37 in Figure 11). For example, the antenna with the highest average SNR value for each distributed station may be selected as the reference antenna. The determination of the reference antenna may be made, for example, based on the reception result of the SRS, which is the uplink reference signal in the most recent or past radio frame, or the reception result report from the UE 2, such as the CSI-RS, which is the downlink reference signal in the most recent or past radio frame.

[0111] <Fourth Embodiment> In the first to third embodiments, the control device 1 determined the timing for reporting the phase offset for UE 2. In the fourth embodiment, UE 2 determines the timing for reporting the phase offset based on the measurement result of the phase offset value in UE 2. In the fourth embodiment, explanations common to the first embodiment are omitted. In the fourth embodiment, the system configuration and the hardware and functional configuration of the control device 1 are the same as in the first embodiment.

[0112] In the fourth embodiment, the control device 1 notifies the UE 2 of the phase offset reporting conditions and the maximum reporting period T_(Φmax). The phase offset reporting conditions are, for example, that the phase offset value is greater than the threshold Δ_(Φ). For each distributed station, the UE 2 reports the phase offset value when the reporting conditions are met or when the maximum reporting period T_(Φmax) has elapsed since the last phase offset report. However, the phase offset reporting conditions are not limited to these. The threshold Δ_(Φ) and the maximum reporting period T_(Φmax) of the phase offset value may be fixed values ​​set in advance by the administrator of the communication system 100, or they may be calculated at a predetermined timing using a predetermined method. The timing at which the threshold Δ_(Φ) and the maximum reporting period T_(Φmax) of the phase offset value are calculated may be, for example, the start of a radio frame, the start of a predetermined slot, or the execution of a distributed station selection.

[0113] Figure 12 shows an example of the hardware configuration of UE 2. UE 2 includes a CPU 201, main memory 202, external storage 203, wireless communication device 204, and antenna 205. The CPU 201, main memory 202, and external storage 203 are the same as those of CPU 101, main memory 102, and external storage 103.

[0114] 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 2 on the control plane. The hardware configuration of the UE 2 is not limited to that shown in Figure 12. Depending on the type, the UE 2 may further include a touch panel display, microphone, speaker, and operation buttons in addition to the components shown in Figure 12.

[0115] Figure 13 shows an example of the functional configuration of UE 2 according to the fourth embodiment. UE 2 comprises a control unit 21 and a measurement unit 22 as its functional configuration. The functions of the control unit 21 and the measurement unit 22 are achieved by the CPU 201 executing a predetermined program.

[0116] The control unit 21 controls the reporting of the phase offset in UE 2. The control unit 21 receives information on the reference station and distributed stations, the allocation of radio resources for measuring the phase offset, reporting conditions, and the longest reporting period T_(Φmax) from the control device 1.

[0117] The control unit 21 determines whether or not to report the phase offset value for each distributed station other than the base station, based on the reporting conditions. If the reporting conditions are met, the control unit 21 decides to report the phase offset value for that distributed station. If the reporting conditions are not met, the control unit 21 decides not to report the phase offset value for that distributed station.

[0118] In the fourth embodiment, the reporting condition for the phase offset is that the phase offset value is greater than the threshold Δ_(Φ). Therefore, the control unit 21 decides to report to the control device 1 the set of phase offset values ​​for distributed station #n at timing k, Φ_(n,k) = {Φ_(n,0,k), Φ_(n,1,k), ..., Φ_(n,N_(SB)-1,k)}, which is input from the measurement unit 22 described later, if the phase offset value in at least one subband is greater than the threshold Δ_(Φ).

[0119] Furthermore, the control unit 21 also decides to perform a phase offset report for each distributed station if the longest reporting period T_(Φmax) has elapsed since the last phase offset report was made. If the control unit 21 decides to perform a phase offset for any distributed station, it requests a radio resource for reporting from the control device 1. The control unit 21 uses the radio resource for reporting notified by the control device 1 to report the phase offset for the relevant distributed station to the control device 1.

[0120] The measurement unit 22 receives information about the base station and distributed stations, and the allocation of radio resources for phase offset measurement, from the control unit 21, which are notified by the control device 1. The base station and each distributed station transmit CSI-RS, which is a signal for phase offset measurement, in synchronization at a predetermined period according to the allocation of radio resources for phase offset measurement. The measurement unit 22 receives the CSI-RS transmitted from the base station and each distributed station according to the allocation of radio resources for phase offset measurement. Each time the measurement unit 22 receives CSI-RS, it acquires the amount of phase rotation of the received signals from the base station and each distributed station in each subband, and for each distributed station, it acquires the difference in the amount of phase rotation of the received signals from the base station in each subband as the phase offset value, and for each distributed station, it outputs a set of phase offset values ​​at timing k Φ_(n,k) = {Φ_(n,0,k), Φ_(n,1,k), ..., Φ_(n,N_(SB)-1,k)} to the control unit 21. The processing performed by the measurement unit 22 is common to all three embodiments.

[0121] Figure 14 is an example of a flowchart of the phase offset reporting process of UE 2 according to the fourth embodiment. The process shown in Figure 14 is repeatedly executed while the wireless communication device 204 of UE 2 is in operation. The main entity executing the process shown in Figure 14 is the CPU 201 of UE 2, but for convenience, the functional components will be described as the main components. The process shown in Figure 14 is executed for each distributed station.

[0122] In OP51, the control unit 21 determines whether a set of phase offset values ​​for timing k has been input from the measurement unit 22 for each distributed station. If a set of phase offset values ​​for timing k for each distributed station has been input (OP51: YES), the process proceeds to OP52. If a set of phase offset values ​​for timing k for each distributed station has not been input (OP51: NO), the process shown in Figure 14 ends.

[0123] The processing from OP52 to OP55 is performed for each distributed station. During the processing from OP52 to OP55, it is determined whether or not a phase offset report should be performed for each distributed station. The distributed station that is subject to the processing from OP52 to OP55 is denoted as distributed station #n.

[0124] In OP52, the control unit 21 determines whether the reporting conditions are met for distributed station #n. If the reporting conditions are met (OP52: YES), the process proceeds to OP53, where the control unit 21 decides to report the phase offset for distributed station #n. If the reporting conditions are not met (OP52: NO), the process proceeds to OP54. Note that if the reporting conditions have not been notified by the control device 1, OP52 may be an affirmative determination.

[0125] In OP54, the control unit 21 determines whether the longest reporting period T_(Φmax) has elapsed since the last phase offset report for distributed station #n. If the longest reporting period T_(Φmax) has elapsed since the last phase offset report for distributed station #n (OP54: YES), the process proceeds to OP53, where the control unit 21 decides to perform a phase offset report for distributed station #n. If the longest reporting period T_(Φmax) has not elapsed since the last phase offset report for distributed station #n (OP54: NO), the process proceeds to OP55, where the control unit 21 decides not to perform a phase offset report for distributed station #n. Once the processing of OP52 to OP55 is completed for all distributed stations, the process proceeds to OP56.

[0126] In OP56, the control unit 21 determines whether or not there are distributed stations for which a phase offset report has been decided. If there are distributed stations for which a phase offset report has been decided (OP56: YES), the process proceeds to OP57. If there are no distributed stations for which a phase offset report has been decided (OP56: NO), the process shown in Figure 14 ends.

[0127] In OP57, the control unit 21 sends a request to the control device 1 for the allocation of wireless resources for reporting. In OP58, the control unit 21 determines whether or not it has received the allocation of wireless resources for reporting from the control device 1. If the allocation of wireless resources for reporting is received (OP58: YES), the process proceeds to OP59. If the allocation of wireless resources for reporting is not received (OP58: NO), the control unit 21 waits until it is received. If it is not received after a predetermined time has elapsed, the process shown in Figure 14 may be terminated as an error.

[0128] In OP59, the control unit 21 uses the notified radio resource for reporting to transmit to the control device 1 the set of phase offset values ​​at timing k input in OP51 for the distributed stations for which reporting of phase offset has been decided, thereby reporting the phase offset. After that, the process shown in Figure 14 is completed.

[0129] Figure 15 shows an example of a processing sequence related to reporting a phase offset in the communication system 100 according to the fourth embodiment. The assumptions for the example shown in Figure 15 are the same as those for Figures 6 and 11.

[0130] In S41, the control device 1 selects the distributed stations to perform coordinated transmission to UE 2 and selects the base station. In S42, the control device 1 allocates radio resources for phase offset measurement to the base station and distributed stations determined in S41. In S43, the control device 1 notifies UE 2 of the base station and at least one distributed station selected in S41, the allocation of radio resources for phase offset measurement, the reporting conditions, and the maximum reporting period. The control device 1 also notifies the base station and each distributed station of the allocation of radio resources for phase offset measurement.

[0131] In S44, UE 2 receives signals for phase offset measurement from the base station and each distributed station, and measures the phase offset from the received signal from the base station (reference signal) for each predetermined number of subbands of the received signal from each distributed station.

[0132] In S45, UE 2 determines whether or not to report the phase offset for each distributed station, depending on whether the reporting conditions are met (Figure 14, OP52-OP55). In the example shown in Figure 15, it is assumed that there are distributed stations for which it has been decided to report the phase offset.

[0133] In S46, UE 2 sends a request to control device 1 for the allocation of radio resources for reporting (Figure 14, OP 57). In S47, control device 1 allocates radio resources for UE 2's phase offset reporting. In S48, control device 1 notifies UE 2 of the allocation of radio resources for phase offset reporting, and UE 2 receives the notification (Figure 14, OP 58: YES). In S49, UE 2 sends to control device 1, as a phase offset report, the set of phase offset values ​​for timing k measured in S44 for distributed stations for which reporting of phase offsets has been decided (Figure 14, OP 59).

[0134] In S50, the control device 1 performs phase offset compensation for each distributed station that has reported a phase offset, based on the set of phase offset values ​​received from UE 2. Subsequently, if there are any distributed stations that meet the reporting conditions, UE 2 reports the phase offset of those distributed stations.

[0135] In the fourth embodiment, UE 2 determines whether or not to report a phase offset for each distributed station based on the set of phase offset values ​​at timing k. As a result, phase offset reporting is performed at a timing corresponding to the phase offset, and phase offset compensation is also performed, so that UE 2 can obtain the gain of the received signal by CJT with less loss. Furthermore, if the reporting condition is that the phase offset value is greater than the threshold Δ_(Φ), it is expected that after phase offset compensation is performed, it will take some time for the reporting condition to be met again for that distributed station. For example, when UE 2 is stationary, the change in the radio wave propagation environment is small, so the duration of the effect of phase offset compensation will be longer, and it is expected that it will take time for the phase offset to become greater than the threshold Δ_(Φ) again. Therefore, the frequency of phase offset reporting from UE 2 will also decrease, and overhead can be reduced.

[0136] In the fourth embodiment, if UE 2 has multiple antennas, the control device 1 may select a reference antenna and notify UE 2 of the reference antenna along with reporting conditions. UE 2 may then determine whether the reporting conditions are met for each distributed station based on the set of phase offset values ​​measured from the CSI-RS received by the reference antenna, and if the reporting conditions are met, report to the control device 1 (S44 to S46 in Figure 15). For example, the antenna with the highest average SNR for each distributed station may be selected as the reference antenna. The determination of the reference antenna may be based, for example, on the reception result of the SRS, which is the uplink reference signal in the most recent or past radio frame, or on the reception result report from UE 2, such as the CSI-RS, which is the downlink reference signal in the most recent or past radio frame. Alternatively, the selection criteria for the reference antenna may be transmitted to UE 2 along with reporting conditions, and UE 2 may select the reference antenna.

[0137] <Other Embodiments> The embodiments described above are merely examples, and this disclosure may be modified as appropriate without departing from its essence.

[0138] The control device 1 may switch the method for controlling the reporting of phase offset from UE 2 based on the movement state of UE 2, between the methods described in the first to fourth embodiments. For example, the control device 1 can obtain the movement state of UE 2 by having UE 2 report its movement speed at a predetermined interval, or by obtaining movement information of UE 2 from a 5G core or the like. For example, when UE 2 is stationary, the control device 1 controls the reporting of phase offset from UE 2 using the method described in the first embodiment, and when UE 2 is moving at a predetermined speed, the control device 1 may control the reporting of phase offset from UE 2 using one of the methods described in the second to fourth embodiments. Which of the methods described in the second to fourth embodiments is used may be determined, for example, based on whether there is sufficient available channel bandwidth. For example, if there is sufficient available bandwidth, the method for controlling the reporting of phase offset from UE 2 described in the third embodiment may be selected. For example, if there is insufficient available bandwidth, a method for controlling the reporting of the phase offset from UE 2 as described in the second or fourth embodiment may be selected.

[0139] The processing of the control device 1 in the first to fourth embodiments may be performed by one of the relay stations if the signal to the base station among the distributed stations, or to the UE 2, is relayed by one or more relay stations. Also, if the signal to the UE 2 is relayed by one or more relay stations, the relay station may perform the same processing on the transmitting and receiving point as the UE 2 in the first to fourth embodiments.

[0140] In the first to fourth embodiments, the communication system 100 was described on the premise that it is a distributed MIMO system. However, it is not limited to this, and the base station selection process described in the first and second embodiments can be applied to systems in which coordinated transmission is performed, such as MIMO systems.

[0141] Furthermore, the processes and means described in this disclosure can be freely combined and implemented, provided that no technical inconsistencies arise.

[0142] 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.

[0143] 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.

[0144] 1...Control unit 2...UE 11...Control unit 21...Control unit 22...Measurement unit 100...Communication system 101...CPU 102...Main memory 103...External memory 104...Communication device

Claims

1. A method for a computer to perform the following: acquire first information relating to a phase change of a first signal transmitted from a first transmitting / receiving point that transmits a signal synthesized in the first device to the first device in coordination with at least one other transmitting / receiving point; and determine, based on the first information, the timing at which the first device reports a phase offset, which is the phase difference of the first signal from a reference signal.

2. The method according to claim 1, wherein the computer acquires information as first information that reflects at least one of the following: changes in the radio wave propagation environment, changes in the characteristics of the RF (Radio Frequency) circuit provided in the first transmitting and receiving point and the first device, and the influence of the stability of the carrier frequency at the first transmitting and receiving point.

3. The method according to claim 1, wherein the computer obtains the stability of the carrier frequency at the first transmission / reception point as first information.

4. The method according to claim 3, wherein the computer obtains a first phase deviation for the first signal from the stability of the carrier frequency at the first transmitting and receiving point and the carrier frequency, and determines the reporting period of the phase offset such that the second phase deviation for the first signal that is permissible in signal synthesis in the first device is less than or equal to the value obtained by dividing it by the first phase deviation.

5. The method according to claim 3, wherein the computer obtains a required value, defined in a predetermined specification for the stability of the oscillation frequency at the first transmitting and receiving point, as the stability of the carrier frequency at the first transmitting and receiving point.

6. The method according to claim 3, wherein the computer obtains an approximate value of the stability of the carrier frequency at the first transmitting and receiving point, based on measured values ​​of the phase rotation amount at at least two time points obtained from the signal transmitted or received at the first transmitting and receiving point.

7. The method according to claim 1, wherein the computer obtains, as first information, a set of measured values ​​of phase rotation amounts obtained from a signal transmitted or received at the first transmitting / receiving point at multiple points in time that are included in a first period that is included in the period from the start of use of the frequency channel currently in use in communication between the first transmitting / receiving point and the first device to the present, and determines the reporting period of the phase offset based on the rate of phase change of the signal transmitted or received at the first transmitting / receiving point, as indicated by the set of measured values ​​of phase rotation amounts.

8. The method according to claim 7, wherein the computer acquires a first value as information indicating the speed of the phase change of the signal, based on the time difference between the two measured values ​​in each of the one or more combinations of two measured values ​​from the set of measured values ​​of the phase rotation amount in which the difference is greater than or equal to a threshold value, and determines the reporting period of the phase offset to be less than or equal to the first value.

9. The method according to claim 8, wherein the computer obtains the minimum or average value of the time difference between the two measured values ​​in each of the one or more combinations as the first value.

10. The method according to claim 1, wherein the computer obtains, as first information, a predetermined number of phase offset values ​​in each of a predetermined number of subbands acquired by the first device, and determines the reporting period of the phase offset based on the change in the predetermined number of phase offset values ​​between the predetermined number of subbands.

11. The method according to claim 10, wherein the computer obtains a second value based on a predetermined number of phase offset values, obtains a third value based on the second value and a predetermined reporting period, and determines the reporting period of the phase offset such that it is less than or equal to the third value.

12. The method according to claim 11, wherein the computer obtains the average value of a predetermined number of phase offset values ​​as a second value, and obtains a value obtained by multiplying the value obtained by dividing the allowable value of the phase offset value by the second value by the predetermined reporting period as a third value.

13. The method according to claim 1, wherein the computer is the first device, and the computer acquires a predetermined number of phase offset values ​​in each of a predetermined number of subbands as first information, determines whether a predetermined condition regarding the phase offset value is met for the first transmitting and receiving point using the first information, and if the predetermined condition is met, decides to perform a phase offset report for the first transmitting and receiving point and transmits a request for the allocation of radio resources to be used for the report.

14. The method according to claim 13, wherein the predetermined condition is that any of the predetermined number of phase offset values ​​in each of the predetermined number of subbands is greater than a predetermined threshold.

15. The method according to claim 13, wherein the computer receives the predetermined conditions from a control device that controls the transmission and reception points.

16. The method according to claim 1, wherein the computer further performs the following: obtaining the reporting period of the phase offset based on the first information; allocating a radio resource used for reporting the phase offset by the first device based on the reporting period of the phase offset; and notifying the first device of the allocation of the radio resource.

17. An information processing device comprising: a control unit that performs the following: acquiring first information regarding a phase change of a first signal transmitted from a first transmitting / receiving point that transmits a signal synthesized in the first device to the first device in coordination with at least one other transmitting / receiving point; and determining, based on the first information, the timing at which the first device reports a phase offset, which is the phase difference of the first signal from a reference signal.

18. The information processing apparatus according to claim 17, wherein the control unit acquires, as first information, a predetermined number of phase offsets in each of a predetermined number of subbands acquired by the first apparatus, and determines the reporting period of the phase offsets based on the change of the predetermined number of phase offsets between the predetermined number of subbands.

19. The information processing device according to claim 17, wherein the information processing device is the first device, and the control unit acquires a predetermined number of phase offsets in each of a predetermined number of subbands as first information, determines whether predetermined conditions relating to the phase offsets have been met using the first information, and decides to perform a report of the phase offsets if the predetermined conditions have been met, and transmits a request for the allocation of radio resources to be used for the report.

20. A program for causing a computer to perform the following: acquire first information relating to a phase change of a first signal transmitted from a first transmitting / receiving point that transmits a signal synthesized in the first device to the first device in coordination with at least one other transmitting / receiving point; and determine, based on the first information, the timing at which the first device reports a phase offset, which is the phase difference of the first signal from a reference signal.

21. A method for a user device (UE) to perform the following: combine at least two received signals transmitted in coordination from a first transmitting / receiving point and at least one other transmitting / receiving point; and report a phase offset, which is the phase difference of the first signal from a reference signal, at a timing determined based on first information relating to a phase change of the first signal transmitted from the first transmitting / receiving point.

22. The method according to claim 21, further comprising the UE receiving notification of the allocation of radio resources based on the reporting period of the phase offset obtained based on the first information, and reporting the phase offset based on the allocation of radio resources.

23. The method according to claim 22, wherein the first information is the stability of the carrier frequency at the first transmitting and receiving point.

24. The method according to claim 23, wherein the reporting period of the phase offset is determined to be less than or equal to the value obtained by dividing the first phase deviation for the first signal, which is allowed in signal synthesis, by the first phase deviation for the first signal obtained from the stability of the carrier frequency at the first transmitting and receiving point and the carrier frequency.

25. The method according to claim 23, wherein the stability of the carrier frequency at the first transmitting / receiving point is a required value determined by a predetermined specification with respect to the stability of the oscillation frequency at the transmitting / receiving point.

26. The method according to claim 23, wherein the stability of the carrier frequency at the first transmitting and receiving point is an approximation of the stability of the carrier frequency at the first transmitting and receiving point, obtained based on measured values ​​of the amount of phase rotation at at least two time points obtained from the signal transmitted or received at the first transmitting and receiving point.

27. The method according to claim 22, wherein the first information is a set of measured values ​​of phase rotation amounts obtained from a signal transmitted or received at the first transmitting / receiving point at multiple points in time that are included in a first period that is included in the period from the start of use of the frequency channel currently in use in communication between the first transmitting / receiving point and the UE to the present, and the reporting period of the phase offset is determined based on the rate of phase change of the signal transmitted or received at the first transmitting / receiving point, as indicated by the set of measured values ​​of phase rotation amounts.

28. The method according to claim 27, wherein the reporting period of the phase offset is determined to be less than or equal to a first value obtained as information indicating the speed of the phase change of the signal, based on the time difference between the two measured values ​​in each of the one or more combinations of two measured values ​​from the set of measured values ​​of the phase rotation amount in which the difference is greater than or equal to a threshold value.

29. The method according to claim 28, wherein the first value is the minimum or average value of the time difference between the two measured values ​​in each of the one or more combinations.

30. The method according to claim 22, wherein the reporting period of the phase offset is determined based on the change between the predetermined number of subbands of the predetermined number of phase offset values ​​in each of the predetermined number of subbands, which is obtained in the UE as first information.

31. The method according to claim 30, wherein the reporting period of the phase offset is determined to be less than or equal to a third value obtained based on a second value based on a predetermined number of phase offset values ​​and a predetermined reporting period.

32. The method according to claim 31, wherein the second value is the average value of a predetermined number of phase offset values, and the third value is obtained by multiplying the value obtained by dividing the allowable value of the phase offset by the second value by the predetermined reporting period.

33. The method according to claim 21, wherein the UE obtains a predetermined number of phase offset values ​​in each of a predetermined number of subbands as first information, determines whether predetermined conditions regarding the phase offset values ​​are met for the first transmitting and receiving point using the first information, and if the predetermined conditions are met, decides to perform a phase offset report for the first transmitting and receiving point and transmits a request for the allocation of radio resources to be used for the report.

34. The method according to claim 33, wherein the predetermined condition is that any of the predetermined number of phase offset values ​​in each of the predetermined number of subbands is greater than a predetermined threshold.

35. The method according to claim 33, wherein the UE receives the predetermined conditions from a control device that controls the transmitting and receiving points.

36. User equipment comprising a control unit that performs: combining at least two received signals transmitted in coordination from a first transmitting / receiving point and at least one other transmitting / receiving point; and reporting a phase offset, which is the phase difference of the first signal from a reference signal, at a timing determined based on first information relating to the phase change of the first signal transmitted from the first transmitting / receiving point.

37. A program for causing a computer to perform the following: combine at least two received signals transmitted in coordination from a first transmitting / receiving point and at least one other transmitting / receiving point; and report a phase offset, which is the phase difference of the first signal from a reference signal, at a timing determined based on first information relating to the phase change of the first signal transmitted from the first transmitting / receiving point.

Images