Method, wireless communication device, and program

Abstract

To reduce power consumption by measurement for a plurality of beams.SOLUTION: The radio communication device executes measurement of a plurality of beams transmitted from one or a plurality of transmission points in a first cycle, and transmission of a measurement result of the plurality of beams to a predetermined device. The plurality of beams include one or more data communication beams and one or more measurement beams. The radio communication device stops measurement of one or more first beams having high temporal and spatial correlations with the one or more data communication beams among the one or more measurement beams.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to beam management in wireless communications. [Background technology]

[0002] In wireless communications such as the 5th Generation Mobile Communication System (5G), distributed MIMO (Multi-Input Multi-Output) is proposed, which selects one or more antennas near a mobile station from among multiple antennas distributed within the communication area of ​​a single base station for communication. Distributed MIMO reduces blind spots in radio waves by distributing antennas, and can reduce the impact of obstructions. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP TR 38.802 V14.2.0 (2017-09) [Non-patent document 2] 3GPP TS 38.214 V18.2.0 (2024-03) [Non-patent document 3] 3GPP TS 38.213 V18.2.0 (2024-03) Summary of the Invention [Problem to be solved by the invention]

[0004] When multiple transmitting antennas are used, such as in distributed MIMO, a mobile station communicates using a beam designated by a network-side control device. The radio wave strength of the radio signal transmitted by the beam changes over time due to the movement of the mobile station and changes in the surrounding environment. Therefore, the mobile station measures the received signal strength of multiple beams, including a beam for data communication, periodically, for example, for each radio frame or slot, and reports the measurement results to the network-side control device. An example of the received signal strength of a beam is RSRP (Reference Signal Received Power), which is the received power using a reference signal. A reference signal is a signal This signal is intended to measure the wave propagation environment. Based on the measurement results from the mobile station, the control device reselects the beam pattern of each of multiple beams, including the beam for data communication, to be more appropriate in response to changes in the mobile station's movement and the surrounding environment. This makes it possible to provide the mobile station with a data communication beam that can provide wireless communication of higher quality each time in response to changes in the mobile station's movement and the surrounding environment. The beam pattern is simply the direction and width of the beam.

[0005] However, since a mobile station periodically measures RSRP and other parameters for one or more beams from multiple transmission points located within the communication area of ​​a base station as measurement beams along with data communication beams, the measurements can increase power consumption.

[0006] One aspect of the present disclosure is to provide a method, a wireless communication device, and a program that can reduce power consumption due to measurement of multiple beams. [Means for solving the problem]

[0007] One aspect of the present disclosure is A wireless communication device performing measurements at a first period for a plurality of beams transmitted from one or a plurality of transmitting points; transmitting the measurement results of the plurality of beams to a predetermined device; Run The plurality of beams include one or more beams for data communication and one or more beams for measurement. , including The wireless communication device stopping measurement of one or more first beams that have a high temporal and spatial correlation with the one or more data communication beams among the one or more measurement beams; It is a method.

[0008] Another aspect of the present disclosure is performing measurements at a first period for a plurality of beams transmitted from one or a plurality of transmitting points; transmitting the measurement results of the plurality of beams to a predetermined device; a control unit that executes the the plurality of beams include one or more beams for data communication and one or more beams for measurement; The control unit stopping measurement of one or more first beams that have a high temporal and spatial correlation with the one or more data communication beams among the one or more measurement beams; It is a wireless communication device.

[0009] According to one aspect of the present disclosure, it is possible to provide a method, a wireless communication device, and a program that can reduce power consumption due to measurement of multiple beams. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating an example of a system configuration of a communication system according to the first embodiment. [Figure 2] FIG. 2 is a diagram illustrating a hardware configuration of a mobile station. [Figure 3] FIG. 3 is a diagram illustrating an example of the functional configuration of a mobile station. [Figure 4] FIG. 4 is an example of a flowchart of a process for reporting the measurement results of the RSRP of a beam set by a mobile station. [Figure 5]FIG. 5 is an example of a flowchart of a measurement stop beam determination process in a mobile station. [Figure 6] FIG. 6 is an example of a flowchart of a process for reporting RSRP measurement results of a beam set by a mobile station in a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] One aspect of the present disclosure is a method in which a wireless communication device performs measurements on multiple beams transmitted from one or more transmission points at a first period and transmits measurement results of the multiple beams to a predetermined device. The multiple beams may include one or more data communication beams and one or more measurement beams. The wireless communication device may stop measuring one or more first beams, among the one or more measurement beams, that have a high temporal and spatial correlation with the one or more data communication beams.

[0012] The wireless communication device is, for example, a terminal station or a relay station. The terminal station is, for example, a mobile station of a user terminal such as a smartphone, a tablet terminal, or an in-vehicle device. However, without being limited to this, the terminal station may also be a stationary terminal that does not move. The wireless communication device measures, for example, the received signal strength (RSRP) of a reference signal transmitted from one or more transmission points at a first period. However, the object that the wireless communication device measures with respect to a beam is not limited to RSRP, and may be, for example, a received signal strength indicator (RSSI), a reference signal received quality (RSRQ), and a signal to interference and noise power ratio (SI The transmission point may be, for example, a signal to interference plus noise ratio (NR). , a base station and a relay station equipped with an antenna, or an antenna equipped in the base station and the relay station The predetermined device to which the measurement results of the multiple beams are transmitted is, for example, a base station or a control device that controls the base station.

[0013] The wireless communication device may calculate a correlation coefficient of a predetermined number of measurement values ​​for each of one or more measurement beams with each of one or more data communication beams, and may designate a measurement beam whose correlation coefficient with at least one of the one or more data communication beams is greater than or equal to a first threshold as a first beam and stop measurement.

[0014] According to one aspect of the present disclosure, measurement of one or more first beams, among one or more measurement beams, that have a high temporal and spatial correlation with a data communication beam is stopped. This reduces the number of beams to be measured, thereby reducing the power consumption of the wireless communication device related to beam measurement. Furthermore, the temporal and spatial trends of the first beam are likely to be similar to the measurement results of the data communication beam. Therefore, for example, the impact of not measuring the first beam can be reduced when determining whether to report the measurement results of the multiple beams to a predetermined device based on the measurement results of the first beam. Furthermore, when the predetermined device selects new multiple beams based on the measurement results of the multiple beams, the impact of not measuring the first beam can be reduced by, for example, substituting the measurement results of the first beam with the measurement results of the data communication beam.

[0015] In one aspect of the present disclosure, a wireless communication device may resume measurement of at least one of one or more first beams when a predetermined event occurs. The predetermined event may be, for example, the number of measurements since measurement of the first beam was stopped reaching a first value, the measurement value of at least one of the one or more data communication beams becoming equal to or less than a second threshold, a decrease in the measurement value of at least one of the one or more data communication beams from the previous measurement being equal to or greater than a third threshold, a change in the orientation of the wireless communication device being equal to or greater than a fourth threshold, or a movement speed of the wireless communication device being equal to or greater than a fifth threshold. Any of these events indicates a change in the radio wave reception environment of the wireless communication device. Therefore, according to one aspect of the present disclosure, measurement of the first beam whose measurement has been stopped can be resumed in response to a change in the radio wave reception environment of the wireless communication device, thereby suppressing an impact on the quality of wireless communication due to the stoppage of measurement of the first beam.

[0016] The first value, which is one of the events that triggers the restart of measurement of a first beam, may be determined so that measurement of one or more first beams is restarted no later than the first periodic time length of the end of the validity period of the multiple beams. The validity period of the multiple beams is, for example, from the start of measurement of the multiple beams until the maximum duration has elapsed or until the longest reporting period has elapsed. By determining the first value as described above, multiple beams newly selected by the control device or base station upon the elapse of the maximum duration of the multiple beams or the longest reporting period are determined based on the measurement values ​​of all currently selected multiple beams. This makes it possible to suppress the impact of stopping measurement of a first beam on the quality of wireless communication.

[0017] Furthermore, the first value may be obtained by dividing the time required to move a predetermined distance based on the beam width of one of one or more data communication beams by the time length of the first period. The fifth threshold, which is one of the events that triggers the resumption of measurement of the first beam, when the movement speed of the wireless communication device becomes equal to or greater than the fifth threshold, may be obtained by dividing the predetermined distance based on the beam width of one of one or more data communication beams by the time length of the first period. This makes it possible for the wireless communication device to resume measurement of the first beam before it moves out of the beam width of the data communication beam, i.e., before a change in the radio wave reception environment occurs. Then, multiple new beams are selected by the control device or the base station, and the newly selected multiple beams are determined based on the measurement values ​​of all the current multiple beams. This makes it possible to suppress the impact on the quality of wireless communication caused by stopping the measurement of the first beam.

[0018] In one aspect of the present disclosure, when a predetermined event occurs, the wireless communication device may resume measurement of one or more first beams that are transmitted from the same transmission point as one or more data communication beams. This is because the area to which the wireless communication device moves from an area where data communication beams are effective is likely to be an area where beams transmitted from the same transmission point as the data communication beams are effective. This makes it possible to reduce power consumption due to beam measurement by the wireless communication device while accommodating movement of the wireless communication device.

[0019] In one aspect of the present disclosure, when a predetermined event occurs, the wireless communication device may resume measurement of one or more first beams whose average measurement value is equal to or greater than a second value based on the measurement values ​​of one or more data communication beams. The measurement value of the first beam is the value before the measurement was stopped. In this way, when the predetermined event occurs, measurement of a beam with a better measurement value is resumed among the first beams that have a high correlation with the data communication beam. This makes it possible to preferentially resume measurement of a beam transmitted from a transmission point different from the data communication beam.

[0020] In one aspect of the present disclosure, the wireless communication device may calculate a correlation coefficient of a predetermined number of measurements with one or more data communication beams for each of one or more measurement beams, and determine to stop measurement of at least one of the one or more data communication beams for which a difference between the correlation coefficient up to the previous measurement and the correlation coefficient of the predetermined number of measurements is equal to or less than a sixth threshold, as a candidate first beam, and may determine to continue measurement of all of the one or more data communication beams for which the difference is greater than the sixth threshold. If the difference in correlation coefficients is greater than the sixth threshold, it is likely that the number of samples is insufficient. If the number of samples is insufficient, the reliability of the correlation coefficient is low, and stopping beam measurement may affect wireless communication. Therefore, according to one aspect of the present disclosure, it is possible to suppress the impact of stopping beam measurement on wireless communication.

[0021] Another aspect of the present disclosure can be specified as a wireless communication device that executes the processing of the above-described method. The wireless communication device includes a control unit that performs measurements on multiple beams transmitted from one or more transmission points at a first period and transmits measurement results of the multiple beams to a predetermined device, where the multiple beams include one or more data communication beams and one or more measurement beams, and the control unit stops measurement of one or more first beams, among the one or more measurement beams, that have a high temporal and spatial correlation with the one or more data communication beams. The control unit is, for example, a processor such as a CPU (Central Processing Unit).

[0022] Another aspect can also be specified as a program for causing a receiving device and a transmitting device to execute the method, and a computer-readable, non-transitory storage medium on which the program is recorded.

[0023] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. The configurations of the following embodiments are examples, and the present disclosure is not limited to the configurations of the embodiments.

[0024] First Embodiment FIG. 1 is a diagram showing an example of a system configuration of a communication system 100 according to the first embodiment. The communication system 100 is a distributed MIMO system including a mobile station 1, a control device 2, and a plurality of distributed base stations. The control device 2 is a device on a core network to which the distributed base stations are connected. However, the control device 2 can also be considered to be 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 2 controls the distributed base stations and the mobile station 1.

[0025] A distributed base station, together with other distributed base stations in the same communication area, provides a wireless access network to mobile stations 1 located within the communication area. The three distributed base stations shown in Fig. 1 are assumed to be located within the same communication area. Each of the distributed base stations is connected to a control device 2.

[0026] The distributed base station is equipped with an antenna that can form multiple beam patterns. The antenna equipped in the 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. An adaptive array antenna can adaptively control the weighting of each antenna element according to the radio wave propagation environment, and electrically change the beam pattern. The beam pattern can also be said to be the directivity of the beam formed by the adaptive array antenna. The beam pattern of the distributed base station is controlled by a control device 2. Note that the distributed base station may be equipped with one antenna or multiple antennas.

[0027] The mobile station 1 is, for example, a terminal station such as a smartphone, a tablet terminal, a wearable terminal, or an in-vehicle data communication device. However, without being limited thereto, the mobile station 1 may also be a stationary terminal device. The mobile station 1 may also be a relay station that relays wireless communication between a distributed base station and a terminal station. The relay station may be, for example, a small base station, a mobile base station, an in-vehicle device, or a smartphone. In the first embodiment, the mobile station 1 also has multiple antennas. However, without being limited thereto, the mobile station 1 may also have one antenna.

[0028] The mobile station 1 receives from the control device 2 designations of multiple beams, including data communication beams and measurement beams, and measures the received signal power (RSRP) of the reference signal for the multiple beams at a predetermined interval. Based on reports of the RSRP measurement results for the multiple beams from the mobile station 1, the control device 2 detects changes in the radio wave reception environment of the mobile station 1, selects a new beam set that is more suitable for the radio wave reception environment of the mobile station 1, and notifies the mobile station 1 of the selection.

[0029] The mobile station 1 consumes power by measuring all beams specified by the control device 2 at a predetermined period. Therefore, in the first embodiment, the mobile station 1 reduces the power consumption due to the measurement of the beams of the mobile station 1 by stopping the measurement of the measurement beams that are highly correlated with the data communication beams.

[0030] In the example shown in FIG. 1, distributed base station RU#1 includes transmission points m_(0), m_(1), and m_(2), distributed base station RU#2 includes transmission points m_(3) and m_(4), and distributed base station RU#3 includes transmission points m_(5) and m_(6). Three beams, beams b0, b1, and b2, are transmitted from distributed base station RU#1. Distributed base station RU#1 is also represented as transmission points m_(0), m_(1), and m_(2) of beams b0, b1, and b2. Characters following an underscore or in parentheses are indicated as subscripts in the figure. Two beams, beams b3 and b4, are transmitted from distributed base station RU#2. Two beams, beams b5 and b6, are transmitted from distributed base station RU#3. The following description of report data from mobile station 1 assumes the configuration shown in FIG. 1. Mobile station 1 is an example of a "wireless communication device."

[0031] 2 is a diagram illustrating an example of the hardware configuration of the mobile station 1. The mobile station 1 includes a CPU 101, a main memory device 102, an external memory device 103, an output device 104, an operation device 105, a wireless communication device 106, and an antenna 107. The CPU 101 is also called a processor. The CPU 101 is not limited to a single processor, and may have a multi-processor configuration. In addition to the CPU 101, a graphics processing unit (GPU), a digital signal processor (DSP), etc. may be included. The CPU 101 may also cooperate with a hardware circuit such as a field programmable gate array (FPGA). .

[0032] The CPU 101 executes a computer program that has been loaded in an executable manner into the main memory device 102, and provides processing for the mobile station 1. The main memory device 102 stores the computer program executed by the CPU 101, data processed by the CPU 101, etc. The main memory device 102 may be implemented by a memory such as a dynamic random access memory (DRAM), a static random access memory (SRAM), or a The external storage device 103 is, for example, a storage area that supports the main storage device 102, and stores computer programs executed by the CPU 101, data processed by the CPU 101, etc. The external storage device 103 is, for example, a hard disk drive, a solid state drive (SSD), etc. A drive device for a removable storage medium may be connected to the mobile station 1. The removable storage medium may be, 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 a "control unit" of a "wireless communication device."

[0033] The output device 104 is, for example, a display device such as a liquid crystal display or an electroluminescence panel. However, the output device 104 may also include a speaker or other device for outputting sound. The operation device 105 is, for example, a touch panel with a touch sensor superimposed on a display. The wireless communication device 106 is connected to an antenna 107, and connects to a wireless access network via the antenna 107 by a mobile wireless communication method such as 5G, and receives wireless signals from a distributed base station. The wireless communication device 106 is also connected to the control device 2 on the control plane. Note that the hardware configuration of the mobile station 1 is not limited to that shown in FIG. 2.

[0034] The control device 2 includes a CPU, a main memory device, an external memory device, an output device, an operation device, and a communication device. The CPU, main memory device, external memory device, output device, and operation device of the control device 2 are similar to the CPU 101, main memory device 102, external memory device 103, output device 104, and operation device 105. The communication device of the control device 2 communicates with a distributed base station and an external network such as the Internet via optical fiber, for example. The communication device of the control device 2 may be a single device or a combination of multiple devices. The control device 2 is an example of a "predetermined device."

[0035] 3 is a diagram showing an example of the functional configuration of the mobile station 1. The functional configuration of the mobile station 1 includes a control unit 11, a measurement unit 12, and a measurement result storage unit 13. The functions of the control unit 11, the measurement unit 12, and the measurement result storage unit 13 are achieved by the CPU 101 executing a predetermined program.

[0036] The control unit 11 receives designation of a data communication beam and a measurement beam from the control device 2. The control unit 11 instructs the measurement unit 12 to start measuring the received signal strength ratio (RSRP) of the reference signal for each of the data communication beam and the measurement beam at a predetermined period. Hereinafter, a set of a data communication beam and a measurement beam will be referred to as a beam set. One or more data communication beams may be included in a beam set. At least one measurement beam is included in a beam set from each transmission point within the communication area of ​​the central base station. Hereinafter, the measurement, measurement value, and measurement result of the received signal strength of the reference signal for each beam included in the beam set will be referred to simply as the measurement, measurement value, and measurement result of the RSRP of the beam set, respectively. Also, the measurement value of the received signal strength of the reference signal for each beam included in the beam set may be referred to simply as the RSRP of the beam set or the measurement value of the beam set.

[0037] After measuring the beam set a predetermined number of times, the control unit 11 calculates the correlation coefficient between each measurement beam and the data communication beam using the following equation 1. The correlation coefficient between data communication beam b0 and measurement beam bn is set to r_(K)(b0,bn). n is a variable indicating the number of the measurement beam. n takes a value from 1 to N. N is the number of measurement beams. K is the number of measurements for the beam set. K is also the number of samples.

number

[0038] s_(0,k) is the kth measurement value of data communication beam b0. s_(n,k) is the kth measurement value of measurement beam bn. S_(0,k) is the average of the measurement values ​​up to the kth measurement value of data communication beam b0. S_(n,k) is the average of the measurement values ​​up to the kth measurement value of measurement beam bn.

[0039] The control unit 11 determines whether or not to perform a determination to stop measurement for the measurement beam bn based on the difference |r_(K)(b0,bn)-r_(K-1)(b0,bn)| between the correlation coefficient r_(K-1)(b0,bn) up to the K-1th measurement and the correlation coefficient r_(K)(b0,bn) up to the Kth measurement. If the difference in correlation coefficients is equal to or smaller than a threshold Δr, the control unit 11 determines to perform a determination to stop measurement for the measurement beam bn. If the difference in correlation coefficients is greater than the threshold Δr, the control unit 11 determines that the number of samples for the measurement beam bn is insufficient and determines to continue measurement without performing a determination to stop measurement. The threshold Δr is, for example, Δr=1 / √k. However, the threshold Δr is not limited to this and may be a value obtained by multiplying 1 / √k by a constant. The threshold Δr is an example of a "sixth threshold."

[0040] The control unit 11 determines whether to stop the measurement of the measurement beam bn based on the correlation coefficient r_(K)(b0,bn) up to the Kth time. If the correlation coefficient r_(K)(b0,bn) is equal to or greater than the threshold Tr, it indicates that the measurement beam bn has a high temporal and spatial correlation with the data communication beam b0, and the control unit 11 decides to stop the measurement of the measurement beam bn. If the correlation coefficient r_(K)(b0,bn) up to the Kth time is less than the threshold Tr, it indicates that the measurement beam bn has a low temporal and spatial correlation with the data communication beam b0, and the control unit 11 decides to continue the measurement of the measurement beam bn. The threshold Tr is, for example, 0.75. However, the value of the threshold Tr is not limited to 0.75 and can be adjusted as appropriate by the administrator of the communication system 100. The threshold Tr is an example of a "first threshold." The measurement beam for which it has been determined to stop measurement is an example of a "first beam."

[0041] If the beam set includes multiple data communication beams, the control unit 11 calculates the correlation coefficient r(K)_(b0p,bn) between each measurement beam bn and each data communication beam b0p. p is a variable indicating the number of the data communication beam. p takes a value ranging from 1 to P. P is the number of data communication beams.

[0042] For the measurement beam bn, if the difference in correlation coefficients |r_(K)(b0p,bn)-r_(K-1)(b0p,bn)| is equal to or smaller than the threshold value Δr for at least one data communication beam, the control unit 11 decides to make a determination as to whether to stop the measurement of the measurement beam bn. For the measurement beam bn, if the difference in correlation coefficients |r_(K)(b0p,bn)-r_(K-1)(b0p,bn)| is greater than the threshold value Δr for all data communication beams, the control unit 11 decides to continue the measurement of the measurement beam bn.

[0043] For the measurement beam bn, if the correlation coefficient r_(K)(b0p,bn) for at least one data communication beam is equal to or greater than the threshold value Tr, the control unit 11 decides to stop the measurement of the measurement beam bn. For the measurement beam bn, if the correlation coefficient r_(K)(b0p,bn) for all data communication beams is less than the threshold value Tr, the control unit 11 decides to continue the measurement of the measurement beam bn.

[0044] The control unit 11 instructs the measurement unit 12 to stop measurement of the measurement beam bn for which it has decided to stop measurement. This reduces the number of measurement beams to be measured, thereby reducing the power consumption related to measurement by the mobile station 1. When reporting the measurement results of the beam set to the control device 2, the control unit 11 may, for example, supplement the measurement values ​​of the measurement beams for which measurement is stopped using the measurement values ​​of the data communication beams, or may transmit information indicating that measurement is stopped. When it is reported that measurement is stopped, the control device 2 may supplement the measurement values ​​of the measurement beams for which measurement is stopped using the measurement values ​​of the data communication beams.

[0045] Next, the control unit 11 determines whether to resume measurement of the measurement beam for which measurement has been stopped, when at least one of the following events occurs. (1) The number of measurements since the measurement stopped is K_stop. (2) The measurement value s_(b0,k) of the data communication beam b0 is equal to or less than the threshold value s_TH. The threshold value s_TH is, for example, the receiving sensitivity +10 dB. However, the threshold value s_TH is not limited to this. (3) The amount of decrease Δs_(b0)=s_(b0,k−1)−s_(b0,k) in the RSRP of the data communication beam b0 is equal to or greater than the threshold Δs. The threshold Δs is, for example, 10 dB. However, the threshold Δs is not limited to this. (4) The change amount Δθ of the orientation of the mobile station 1 is equal to or greater than a threshold value Δθ_TH. The threshold value Δθ_TH is, for example, half the beam width of the antenna of the mobile station 1. The threshold value Δθ_TH is an example of a "fourth threshold value." (5) The moving speed of the mobile station 1 becomes equal to or greater than the threshold value v_TH.

[0046] The control unit 11 sets the value of K_stop in the event (1) according to, for example, one of the following (A) to (C). (A) The control unit 11 sets K_stop to a value predetermined by the administrator of the communication system 100.

[0047] (B) The control unit 11 determines K_stop so that measurements of all measurement beams are performed immediately before the beam set is updated according to the update period. The beam set is updated not only based on reports of beam set measurement values ​​from the mobile station 1, but also when the maximum duration specified by the control device 2 has elapsed. The maximum duration is also called lifetime. Therefore, an example of a beam update period is the maximum duration. The longest reporting period of the beam set may also be used as the beam update period. The longest reporting period is, for example, the time length specified by the control device 2 as the longest reporting period, or the longest time length between reports in the report history of beam set measurement values ​​from the mobile station 1. The longest reporting period is a time length equal to or less than the maximum duration. K_stop is, for example, based on the beam update period This is obtained by dividing by the length of time Tm of the measurement cycle and then subtracting K+1 from the result. The length of time Tm of the measurement cycle is, for example, 0.125 ms, which is one of the common slot lengths for 5G. However, the length of time Tm of the measurement cycle is not limited to this.

[0048] By setting K_stop in this way, when there is no change in the radio wave reception environment and the beam set is updated periodically, the measurement values ​​of the current beam set used to select a new beam set by the control device 2 can include the actual measurement values ​​of all measurement beams. This makes it possible to suppress the influence of measurement stoppage of one or more measurement beams on the selection of a new beam set.

[0049] (C) The control unit 11 calculates K_stop from the moving speed v of the mobile station 1 and the distance dn from the transmission point m_(n) to the mobile station 1. For example, the control unit 11 obtains K_stop by dividing the time ΔT_(b0) required to move a distance half the beam width θ_(b0) of the data communication beam b0 by the time length Tm of the measurement period, as shown in the following equation 2.

number

[0050] The distance half the beam width θ_(b0) of the data communication beam b0 is an example of a distance over which the mobile station 1 is likely to fall outside the communication range of the data communication beam b0 if it moves. If the mobile station 1 falls outside the communication range of the data communication beam b0, there is a possibility that a beam with a stronger RSRP than the data communication beam b0 exists, which means that the radio wave reception environment of the mobile station 1 has changed. If the radio wave reception environment of the mobile station 1 has changed, the mobile station 1 is likely to report the measurement value of the beam set to the control device 2, and the beam set will be updated to a new one. Therefore, by calculating K_stop using the above equation 2, it is possible to resume measurement of the measurement beam for which measurement has been stopped before the beam set is updated. Note that the distance over which the mobile station 1 is likely to fall outside the communication range of the data communication beam b0 if it moves, used in equation 2, is not limited to half the beam width θ_(b0) of the data communication beam b0, and may be, for example, a predetermined distance, an average value of half the beam widths of the beams previously used for data communication beams, or the like. K_stop is an example of a "first value." The measurement period of the beam is an example of a "first period." The time length Tm of the measurement period is an example of a "time length of the first period."

[0051] In events (2) and (3), the threshold s_TH of the measurement value of the data communication beam b0 and the threshold Δs of the decrease in RSRP Δs_(b0) of the data communication beam b0 are used. "10 dB" is an example and is not intended to be limiting. The thresholds s_TH and Δs in events (2) and (3) may be set to any value that allows for a margin for probabilistic RSRP fluctuations. Therefore, instead of "10 dB" used for the thresholds s_TH and Δs, a value obtained by multiplying the standard deviation of the data communication beam measured during the measurement of all measurement beams by a constant may be used. The constant by which the standard deviation is multiplied is, for example, 3. However, the constant by which the standard deviation is multiplied is not limited to 3. The threshold s_TH is an example of a "second threshold." The threshold Δs is an example of a "third threshold."

[0052] The threshold v_TH of the moving speed of the mobile station 1 in the event (5) is obtained, for example, from the following equation 3 using the distance dn to the transmission point m_(n), the beam width θ_(b0) of the data communication beam b0, and the measurement period Tm.

number

[0053] The threshold v_TH is the speed at which the mobile station 1 is likely to move out of the communication range of the data communication beam during the measurement period Tm. When the mobile station 1 moves out of the communication range of the data communication beam, there is a high possibility that an update to a new beam set will occur. Therefore, by calculating the threshold v_TH in event (5) according to equation 3, it is possible to resume measurement of the measurement beam for which measurement has been stopped before the beam set is updated. However, the threshold v_TH is not limited to the value calculated by equation 3 above. The threshold v_TH is an example of a "fifth threshold."

[0054] From the above, events (1) to (5) are events that may trigger an update of the beam set. Also, events (2) to (5) are events that cause a change in the radio wave reception environment of mobile station 1. Note that events that may trigger the resumption of measurement of a measurement beam that has been stopped are not limited to the above events (1) to (5). The above events (1) to (5) are examples of "predetermined events."

[0055] In addition, if there are multiple data communication beams, when at least one of events (2) to (5) occurs for at least one data communication beam, measurement of the measurement beam for which measurement has been stopped may be resumed. Also, if there are multiple data communication beams, and the value of K_stop in event (1) is calculated by method (C), the smallest beam width value among the beam widths of the multiple data communication beams may be used. However, this is not limiting.

[0056] The measurement unit 12 starts measuring the RSRP of the beam set at a predetermined period in accordance with instructions from the control unit 11. The RSRP measurement period is, for example, 0.125 ms, which is a typical 5G slot time length. However, the RSRP measurement period is not limited to this. The measurement unit 12 outputs the measured value of the RSRP of the beam set to the control unit 11.

[0057] The measurement result storage unit 13 is created in a storage area of ​​the main storage device 102. The measurement result storage unit 13 stores the measured values ​​of RSRP of the beam set. The measured values ​​of RSRP of the beam set are stored by the control unit 11 every time a measurement is performed. In addition, the measurement result storage unit 13 stores the measured values ​​of RSRP of the beam set when the total data size of the stored measured values ​​of RSRP of the beam set exceeds a predetermined threshold. When a new beam set is received from the control device 2 or a beam selection procedure is executed, the measurement result storage unit 13 deletes all stored data, i.e., refreshes the measurement result storage unit 13, thereby updating the beam set. Note that the functional configuration of the mobile station 1 is not limited to the example shown in FIG. 3.

[0058] Fig. 4 is an example of a flowchart of a process for reporting measurement results of RSRP of a beam set by the mobile station 1. The process shown in Fig. 4 is repeatedly executed while the wireless communication device 106 of the mobile station 1 is in operation. The process shown in Fig. 4 is executed mainly by the CPU 101 of the mobile station 1, but for convenience, the process will be described mainly focusing on the functional components.

[0059] In OP11, the control unit 11 determines whether or not a beam set has been received from the control device 2. If a beam set has been received from the control device 2 (OP11: YES), the process proceeds to OP12. If a beam set has not been received from the control device 2 (OP11: NO), the process proceeds to OP13.

[0060] In OP12, the control unit 11 updates the beam set to be used to the received beam set and refreshes the measurement result storage unit 13. In OP13, RSRP measurements are performed for all beams included in the beam set at the measurement timing of the measurement period, and if the reporting conditions are met, the measurement results of the beam set are reported to the control device 2, thereby executing a full measurement process. The reporting conditions are, for example, that one or more of the following conditions are met: the RSRP of the data communication beam is less than a predetermined threshold, the RSRP of the measurement beam is equal to or greater than a predetermined threshold, and there is a measurement beam with a higher RSRP than the data communication beam. However, the reporting conditions are not limited to these. The report data to the control device 2 includes, for example, the measurement values ​​of the beam set.

[0061] In OP14, the control unit 11 determines whether the number of measurements has reached K. If the number of measurements has reached K (OP14: YES), the process proceeds to OP15. If the number of measurements has not reached K (OP14: NO), the process proceeds to OP11.

[0062] In OP15, the control unit 11 executes a measurement stop beam determination process to determine a measurement beam for which measurement is to be stopped. A beam for which measurement is to be stopped is selected by the measurement stop beam determination process. The measurement stop beam determination process will be described in detail later.

[0063] In OP16, the control unit 11 executes limited measurement processing, which involves performing limited measurements on beams included in the beam set other than the measurement beam selected in OP15, determining whether or not to report to the control device 2, and if it is determined that reporting should be performed, reporting the measurement results to the control device 2. The limited measurement processing in OP16 is the same as the full measurement processing in OP13, except that the target beams are beams included in the beam set other than the measurement beam for which measurement is suspended.

[0064] In OP17, the control unit 11 determines whether any of events (1) to (5) has occurred. If any of events (1) to (5) has occurred (OP17: YES), the process proceeds to OP11, where measurement of all beams included in the beam set is resumed regardless of whether a new beam set has been received (OP11).

[0065] If none of events (1) to (5) occurs (OP17: NO), the process proceeds to OP18. If a new beam set is not received (OP18: NO), the process proceeds to OP16, where the limited measurement process continues. If a new beam set is received (OP18: YES), the process proceeds to OP12, where the limited measurement process is performed. Measurements are taken for all beams that are being measured.

[0066] Fig. 5 is an example of a flowchart of the measurement stop beam determination process of the mobile station 1. The process shown in Fig. 5 corresponds to the process executed in OP15 of Fig. 4. The process shown in Fig. 5 is executed for each measurement beam included in the beam set. Hereinafter, the measurement beam to be processed is referred to as measurement beam bn.

[0067] In OP21, the control unit 11 calculates the correlation coefficient r_(K-1)(b0, bn) between the measurement beam bn and the data communication beam b0 up to the K-1th time, for example, using Equation 1. In OP22, the control unit 11 calculates the correlation coefficient r_(K)(b0, bn) between the measurement beam bn and the data communication beam b0 up to the Kth time, for example, using Equation 1.

[0068] In OP23, the control unit 11 determines whether the difference |r_(K)(b0,bn)-r_(K-1)(b0,bn)| between the correlation coefficient r_(K-1)(b0,bn) up to the previous (K-1)th measurement and the correlation coefficient r_(K)(b0,bn) up to the Kth measurement is equal to or less than a threshold value Δr. If the difference in the correlation coefficients is equal to or less than the threshold value Δr (OP23: YES), the process proceeds to OP24. If the difference in the correlation coefficients exceeds the threshold value Δr (OP23: NO), the process proceeds to OP26, where the control unit 11 determines to continue measuring the measurement beam bn. Then, the process shown in FIG. 5 for the measurement beam bn ends.

[0069] In OP24, the control unit 11 determines whether the correlation coefficient r_(K)(b0, bn) up to the Kth time is equal to or greater than the threshold value Tr. If the correlation coefficient r_(K)(b0, bn) is equal to or greater than the threshold value Tr (OP24: YES), the process proceeds to OP25, where the control unit 11 decides to stop the measurement of the measurement beam bn. Then, the process shown in FIG. 5 for the measurement beam bn ends. If the correlation coefficient r_(K)(b0, bn) is less than the threshold value Tr (OP24: NO), the process proceeds to OP26, where the control unit 11 decides to continue the measurement of the measurement beam bn. Then, the process shown in FIG. 5 for the measurement beam bn ends. When the process shown in FIG. 5 for all measurement beams ends, the process proceeds to OP16 in FIG. 4.

[0070] If there are multiple data communication beams, a correlation coefficient is calculated in OP21 and OP22 for each one-to-one combination of a measurement beam bn and a data communication beam, and if OP23 and OP24 are judged positive in the combination with at least one data communication beam, it is decided to stop measurement of the measurement beam bn. The processing in the mobile station 1 is not limited to the processing shown in Fig. 4 and Fig. 5. For example, the mobile station 1 may execute the processing in OP22 and OP24 to OP26 as the measurement stop beam determination processing without executing the processing in OP21 and OP23 in Fig. 5.

[0071] <Effects of the First Embodiment> In the first embodiment, the number of measurement beams that the mobile station 1 measures at a predetermined period is reduced, thereby reducing the power consumption of the mobile station 1. For example, a measurement beam whose RSRP has a high temporal and spatial correlation with the data communication beam is selected as the measurement beam for which measurement is stopped, based on the correlation coefficient of the above formula 1. Therefore, even if the measurement value of the measurement beam for which measurement is stopped is missing, it has little effect on the result of the determination in the mobile station 1 as to whether or not to report the measurement result of the beam set, and it is possible to make the determination with the same accuracy as when measuring all measurement beams.

[0072] Furthermore, since the measurement beam for which measurement is stopped has a high temporal and spatial correlation with the data communication beam, for example, the measurement value of the measurement beam for which measurement is stopped can be substituted with the measurement value of the data communication beam. Even if the measurement results of the measurement beam are missing in the data reported to the control device 2, the control device 2 can minimize the impact on the selection of a new beam set due to the suspension of measurement of one or more measurement beams by, for example, substituting the measurement value of the measurement beam for which measurement is stopped with the measurement value of the data communication beam.

[0073] In the first embodiment, the occurrence of any of the events (1) to (5) that may trigger an update of the beam set restarts the measurement of the measurement beams for which measurement has been stopped. This increases the likelihood that the data reported to the control device 2 will include the measurement results for all beams included in the beam set, minimizing the impact on the selection of a new beam set by the control device 2.

[0074] <Modification> In the first embodiment, the occurrence of events (1) to (5) restarts the measurement of the measurement beams for which measurement has been stopped, and the measurement is restarted for all beams included in the beam set. In the modified example, instead, the occurrence of events (1) to (5) restarts the measurement of some of the measurement beams for which measurement has been stopped.

[0075] The beam for which measurement is resumed is, for example, a measurement beam corresponding to a communication range to which the mobile station 1 is likely to move. More specifically, the beam for which measurement is resumed is, for example, a measurement beam transmitted from the same transmission point as the data communication beam and a measurement beam whose average RSRP S_(n) is equal to or greater than the value obtained by subtracting a predetermined value from the measurement value s_(0) of the latest data communication beam. The communication range of a measurement beam transmitted from the same transmission point as the data communication beam is likely to be adjacent to the communication range of the data communication beam. Therefore, by resuming measurement of the measurement beam transmitted from the same transmission point as the data communication beam, it is possible to accommodate movement of the mobile station 1 to a communication range adjacent to the communication range of the data communication beam. A measurement beam whose average RSRP S_(n) is equal to or greater than the value obtained by subtracting a predetermined value from the measurement value s_(0) of the latest data communication beam can accommodate movement of the mobile station 1 to a communication range of a beam with a stronger RSRP from a transmission point other than the transmission point of the data communication beam. The predetermined value to be subtracted from the measurement value s_(0) of the latest data communication beam is, for example, 10 dB. However, the predetermined value to be subtracted from the measurement value s_(0) of the latest data communication beam is not limited to 10 dB. Note that the beam for which measurement is resumed is not limited to the beams mentioned above. The value obtained by subtracting the predetermined value from the measurement value s_(0) of the data communication beam is an example of the "second value."

[0076] 6 is an example of a flowchart of a process for reporting the RSRP measurement result of a beam set by the mobile station 1 in the modified example. In FIG. 6, the same reference numerals are used to denote processes common to the first embodiment.

[0077] 6, after a measurement beam for which measurement is to be stopped is selected (OP15), a limited measurement process is performed (OP16), and it is determined whether or not any of events (1) to (5) has occurred (OP17). If any of events (1) to (5) has occurred (OP17: YES), the process proceeds to OP31.

[0078] In OP31, the control unit 11 selects a measurement beam for which measurement is to be resumed from among the measurement beams for which measurement has been stopped. The measurement beam for which measurement is to be resumed is selected, for example, as described above. In OP32, the control unit 11 determines whether the beams to be measured, including the measurement beam for which it has been decided that measurement will be resumed, are all beams included in the beam set. If all beams included in the beam set are to be measured (OP32: YES), the process proceeds to OP11, and thereafter, measurements are performed for all beams included in the beam set. If all beams included in the beam set are not to be measured (OP32: NO), the process proceeds to OP11. ), the process proceeds to OP16, and thereafter, limited measurement processing is performed in which measurement is resumed for the measurement beams for which it was decided in OP31 to resume measurement, but there are measurement beams for which measurement is stopped.

[0079] In the modified example, even if any of events (1) to (5) occurs, measurement is resumed for some of the measurement beams for which measurement was stopped, thereby making it possible to reduce the power consumption of the mobile station 1 while measuring beams that correspond to the movement of the mobile station 1.

[0080] <Other embodiments> The above-described embodiment is merely an example, and the present disclosure can be implemented with appropriate modifications within the scope that does not deviate from the gist of the disclosure.

[0081] In the first embodiment, the communication system 100 has been described assuming that it is a distributed MIMO system. However, the present invention is not limited to distributed MIMO, and the technology described in the first embodiment can also be applied to normal MIMO.

[0082] In the first embodiment, the communication system 100 has been described assuming that it includes a distributed base station and a mobile station 1. However, this is not limiting, and the communication system 100 may include a communication device that is fixed at a predetermined position instead of the mobile station 1.

[0083] In the first embodiment, the measurement of the RSRP of a beam set has been described. However, the present invention is not limited to this, and the technique described in the first embodiment can also be applied to the measurement of the SINR of a beam set, for example. In the first embodiment, by replacing RSRP with SINR and each threshold with a threshold corresponding to SINR, it is possible to determine whether to stop measuring the SINR of a measurement beam and whether to resume measurement, similar to the first embodiment.

[0084] In addition, when stopping measurement of one or more measurement beams based on the RSRP of the beam set, the measurement of measurement targets other than RSRP, such as RSSI (Received Signal Strength Indicator), RSRQ (Reference Signal Received Quality), and SINR, is also performed. Measurement may also be stopped. This is because when RSRP has a high correlation with a data communication beam, for example, the correlation with SINR also tends to be high, so the SINR of the measurement beam for which measurement has been stopped can be substituted with the SINR of the data communication beam. Furthermore, the measurement targets for which measurement can be stopped together with RSRP are not limited to SINR, and measurement can be stopped if fluctuations are linked to RSRP.

[0085] Furthermore, the processes and means described in this disclosure can be freely combined and implemented as long as no technical contradictions arise.

[0086] Furthermore, a process described as being performed by one device may be shared and executed by multiple devices. Alternatively, a process described as being performed by different devices may be executed by one device. In a computer system, the hardware configuration (server configuration) by which each function is realized can be flexibly changed.

[0087] The present disclosure can also be realized by supplying a computer program that implements the functions described in the above embodiments to a computer, and having one or more processors of the computer read and execute the program. Such a computer program may be provided to the computer by a non-transitory computer-readable storage medium connectable to the system bus of the computer, or may be provided to the computer via a network. Non-transitory computer-readable storage media include, for example, magnetic disks (floppy disks, hard disk drives (HDDs), etc.), optical disks (CD-ROMs, This includes any type of medium suitable for storing electronic instructions, such as any type of disk (e.g., DVD disk, Blu-ray disk, etc.), read-only memory (ROM), random-access memory (RAM), EPROM, EEPROM, magnetic card, flash memory, or optical card. [Explanation of symbols]

[0088] 1. Mobile station 2. Control device 11 Control unit 12. Measurement section 13. Measurement result storage unit 100 Communication Systems 101 CPU 102...Main memory 103...External storage device 106 Wireless communication device 107 Antenna

Claims

1. A wireless communication device performing measurements on a plurality of beams transmitted from one or a plurality of transmitting points in a first period; transmitting the measurement results of the plurality of beams to a predetermined device; Run the plurality of beams include one or more beams for data communication and one or more beams for measurement; The wireless communication device stopping measurement of one or more first beams, among the one or more measurement beams, that have a high temporal and spatial correlation with the one or more data communication beams; method.

2. The wireless communication device, calculating a correlation coefficient of measurement values ​​of each of the one or more measurement beams with each of the one or more data communication beams for a predetermined number of times; determining a measurement beam whose correlation coefficient with at least one of the one or more data communication beams is equal to or greater than a first threshold as the first beam, and stopping measurement; The method of claim 1.

3. The wireless communication device, restarting measurement of at least one first beam of the one or more first beams when a predetermined event occurs; The method of claim 1.

4. the predetermined event is that the number of measurements made after stopping the measurement of the one or more first beams reaches a first value; The method of claim 3.

5. The wireless communication device, determining the first value so that measurement of the one or more first beams is resumed at least one time length of the first period before the end of the effective periods of the plurality of beams; The method of claim 4.

6. The wireless communication device, and acquiring the first value by dividing a time required to travel a predetermined distance based on a beam width of one of the one or more data communication beams by a time length of the first period. The method of claim 4.

7. the predetermined event being that a measurement value of at least one of the one or more data communication beams is equal to or less than a second threshold. The method of claim 3.

8. the predetermined event being a decrease in a measurement value of at least one of the one or more data communication beams from a previous measurement that is equal to or greater than a third threshold value; The method of claim 3.

9. The predetermined event is that the orientation of the wireless communication device has changed by a fourth threshold or more. Ru, The method of claim 3.

10. the predetermined event is that the moving speed of the wireless communication device becomes equal to or greater than a fifth threshold. The method of claim 3.

11. The wireless communication device, obtaining the fifth threshold by dividing a predetermined distance based on a beam width of one of the one or more data communication beams by a time length of the first period; The method of claim 10.

12. The wireless communication device, restarting measurement of a beam, among the one or more first beams, that is transmitted from the same transmission point as the one or more data communication beams; The method of claim 3.

13. The wireless communication device, restarting measurement of a beam, among the one or more first beams, whose average value of the measurement values ​​is equal to or greater than a second value based on the measurement values ​​of the one or more data communication beams; The method of claim 3.

14. The wireless communication device, calculating a correlation coefficient of the predetermined number of measurement values ​​between each of the one or more measurement beams and each of the one or more data communication beams; determining whether to stop the measurement of at least one of the one or more data communication beams, for which a difference between a correlation coefficient up to the previous measurement and a correlation coefficient of the predetermined number of measurement values ​​is equal to or less than a sixth threshold, as a candidate for the first beam; determining to continue the measurement for a measurement beam for which the difference is greater than the sixth threshold value with respect to all of the one or more data communication beams; The method of claim 2.

15. performing measurements on a plurality of beams transmitted from one or a plurality of transmitting points in a first period; transmitting the measurement results of the plurality of beams to a predetermined device; a control unit that executes the the plurality of beams include one or more beams for data communication and one or more beams for measurement; The control unit stopping measurement of one or more first beams, among the one or more measurement beams, that have a high temporal and spatial correlation with the one or more data communication beams; Wireless communication device.

16. The control unit calculating a correlation coefficient of measurement values ​​of each of the one or more measurement beams with each of the one or more data communication beams for a predetermined number of times; determining a measurement beam whose correlation coefficient with at least one of the one or more data communication beams is equal to or greater than a first threshold as the first beam, and stopping measurement; 16. The wireless communication device of claim 15.

17. The control unit restarting measurement of at least one first beam of the one or more first beams when a predetermined event occurs; 16. The wireless communication device of claim 15.

18. the predetermined event is a change in orientation of the wireless communication device equal to or greater than a fourth threshold; 18. The wireless communication device of claim 17.

19. The control unit restarting measurement of a beam, among the one or more first beams, that is transmitted from the same transmission point as the one or more data communication beams; 18. The wireless communication device of claim 17.

20. In a wireless communication device, performing measurements on a plurality of beams transmitted from one or a plurality of transmitting points in a first period; transmitting the measurement results of the plurality of beams to a predetermined device; Execute the plurality of beams include one or more beams for data communication and one or more beams for measurement; The wireless communication device, stopping measurement of one or more first beams among the one or more measurement beams that have a high temporal and spatial correlation with the one or more data communication beams; Program for.

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