Radio base station apparatus, radio terminal apparatus, control method, and control program

Abstract

To provide a radio base station apparatus, a radio terminal apparatus, and a control program capable of suppressing deterioration in communication quality.SOLUTION: A radio base station apparatus according to the present disclosure includes a channel gain variation estimation unit that estimates information on channel power gain variation of one or more antennas including a connected antenna, a Doppler frequency variation estimation unit that estimates information on a Doppler frequency variation for the one or more antennas including the connected antenna, and an optimal antenna determination unit that selects one or more optimal connected antennas for a radio terminal based on the information on the channel power gain variation and the information on the Doppler frequency variation.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a wireless base station device, a wireless terminal device, a control method, and a control program. [Background technology]

[0002] To realize high-capacity mobile communication systems such as cellular systems, wireless communication using high-frequency bands such as millimeter waves and terahertz waves, which can utilize wide frequency bandwidths, is becoming increasingly important. While the use of high-frequency bands for mobile communication enables high-capacity communication by utilizing wide frequency bandwidths, it also faces challenges such as large frequency-dependent propagation loss and the large impact of obstructions due to the highly directional nature of radio waves, which make it difficult for them to bend around obstacles.

[0003] One way to solve the former problem of propagation loss is to use beamforming technology, which performs appropriate phase control on radio signals transmitted from multiple antenna elements to increase the reception level of radio signals transmitted in the direction of the communication target. Using beamforming technology makes it possible to compensate for the significant propagation loss associated with high frequency bands. Another way to solve the latter problem of line-of-sight is to use a distributed antenna system (DAS). By extending the base station antenna and distributing multiple antennas, the probability of line-of-sight communication between the antenna and wireless terminals being blocked is reduced.

[0004] Furthermore, in macrocell systems, a related technology, the cell radius is large, and wireless terminals located at the cell edge are far from the base station, resulting in low received power and strong interference from adjacent cells, which leads to a decline in communication quality.One way to solve this problem is to use multiple antennas / cells / TRPs (Transmission Reception Points) / APs (hereinafter referred to as antennas) installed at a relatively high density and coordinate their operation, and technologies such as Coordinated Multi-Point (CoMP), Multi-TRP, and Distributed MIMO have been put into practical use or have been considered.

[0005] Here, for example, in the case of in-vehicle terminals that are mounted on high-speed moving objects such as trains and automobiles and perform high-volume communications, or in wireless environments where wireless terminals move at high speeds, the frequency of switching between the multiple antennas (antennas / cells / TRPs / APs (access points)) of the wireless terminal becomes relatively high, making cooperative operation between the multiple antennas and switching control particularly important.

[0006] In these wireless communication systems, wireless terminals communicate with one or more antennas distributed around the system. When a wireless terminal moves within the system, the antenna used for communication can be switched according to the terminal's movement and changes in channel characteristics, thereby maintaining a connection with a high channel power gain. In order to maintain high communication quality with wireless terminals, it is essential to select and switch appropriate antennas.

[0007] Furthermore, maintaining high communication quality requires accurate synchronization between the antenna and the wireless terminal. In the downlink of a Time Division Duplex (TDD) system, the wireless terminal typically measures the propagation delay between the antenna and the wireless terminal by receiving a Primary Synchronization Signal (PSS) included in a downlink reference signal (e.g., a Synchronization Signal Block (SSB)), and determines the reception timing for subsequent reception. Meanwhile, in the uplink, a Timing Advance (TA) command is notified to the wireless terminal via a Random Access Channel (RACH) procedure between the wireless terminal and the wireless terminal, and the wireless terminal transmits an uplink signal at a timing according to the TA command. By each wireless terminal transmitting according to its notified TA, the times at which the antennas receive signals are synchronized between the wireless terminals.

[0008] Non-Patent Document 1 describes a method for switching the connection destination when the power difference between the downlink reference signal received power (RSRP: Reference Signal Received Power) of the currently connected antenna and the antenna to be switched exceeds a specified offset Off for a certain period of time (TTT: Time-to-Trigger), as shown in Figure 1. By selecting and switching the connected antenna based on the difference in RSRP, it is possible to continue selecting the antenna with the highest gain.

[0009] In the example of FIG. 1, if the state of p1 [dB]-p2 [dB]>Off continues for time TTT or more, switching from base station antenna #2 to base station antenna #1 is performed.

[0010] While the technology described in Non-Patent Document 1 allows for the continuous selection of an antenna with high reception power, it does not take into account changes in the Doppler frequency (Doppler shift) of radio waves due to antenna switching. For example, as shown in Figure 2, if the difference in angle between the direction of movement of a wireless terminal moving at high speed and the direction of each antenna is large between the Doppler frequency f2 between the currently connected antenna #2 and the wireless terminal and the Doppler frequency f1 between the switched-to antenna #1 and the wireless terminal (|f1-f2| >> 0), a reception frequency error may occur in the signal immediately after antenna switching. The reception frequency error occurs when the wireless terminal receives the signal in the downlink and when the antenna receives the signal in the uplink. The difference in reception frequency can cause various problems.

[0011] For example, in an Orthogonal Frequency Division Multiplexing (OFDM) system, a large deviation in the reception frequency can cause interference between OFDM symbols and between subcarriers, resulting in serious degradation of communication quality.

[0012] In the method of Patent Document 1, the wireless terminal can grasp the propagation delay or reception frequency information of the base station antenna to be switched to / added, but when communicating simultaneously with multiple base station antennas, if the Doppler frequency differs significantly between the base station antennas, this may cause a large deviation in the reception frequency at the base station antenna or the wireless terminal, which may result in a deterioration of communication quality.The simultaneous communication may be interpreted as NCJT (Non-Coherent Joint Transmission), CJT (Coherent Joint Transmission), Joint Reception (Joint Reception), etc. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] International Publication No. 2024 / 057525 [Non-patent literature]

[0014] [Non-Patent Document 1] 3GPP TR 38.331 V17.6.0 (2023-09) "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; Radio Resource Control (RRC) protocol specification (Release 17)", September 2023 Summary of the Invention [Problem to be solved by the invention]

[0015] In related art antenna switching using only received power information, there is a problem that large fluctuations occur in the Doppler frequency (received frequency) when switching antennas, resulting in a decrease in communication throughput when switching.

[0016] One object of the present disclosure is to provide a wireless base station device, a wireless terminal device, a control method, and a control program that solve the above-mentioned problems. [Means for solving the problem]

[0017] A radio base station device according to one aspect of the present disclosure includes a channel gain fluctuation estimation unit that estimates information on channel power gain fluctuations of one or more antennas including a currently connected antenna, a Doppler frequency fluctuation estimation unit that estimates information on Doppler frequency fluctuations for one or more antennas including a currently connected antenna, and an optimal antenna determination unit that selects one or more optimal connection antennas for a radio terminal based on the channel power gain fluctuation information and the Doppler frequency fluctuation information.

[0018] A wireless terminal device according to one embodiment of the present disclosure is characterized in that it receives a downlink reference signal from one or more base station antennas, including a connected antenna, and estimates information on Doppler frequency fluctuations, including Doppler frequency differences for multiple antennas and / or information on temporal changes and statistical values ​​of Doppler frequencies for one or more antennas.

[0019] In a control method according to one aspect of the present disclosure, a wireless base station device estimates information on channel power gain fluctuations of one or more antennas including a currently connected antenna, estimates information on Doppler frequency fluctuations for one or more antennas including a currently connected antenna, and selects one or more optimal connection antennas for a wireless terminal based on the channel power gain fluctuation information and the Doppler frequency fluctuation information.

[0020] A control program according to one aspect of the present disclosure causes a computer to execute the following processes: estimating information on channel power gain fluctuations of one or more antennas including the currently connected antenna; estimating information on Doppler frequency fluctuations for one or more antennas including the currently connected antenna; and selecting one or more optimal connection antennas for a wireless terminal based on the channel power gain fluctuation information and the Doppler frequency fluctuation information. [Effects of the Invention]

[0021] The present disclosure can provide a wireless base station device, a wireless terminal device, and a control program that can suppress deterioration of communication quality. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram illustrating a base station antenna switching method in Non-Patent Document 1. [Figure 2] FIG. 1 is a diagram showing an example in which propagation delay changes suddenly when base station antennas are switched in Non-Patent Document 1. [Figure 3] FIG. 1 is a diagram illustrating a method of synchronizing with a base station antenna that is a candidate for switching, as described in Patent Document 1. [Figure 4]FIG. 1 is a diagram illustrating an overview of a wireless communication system according to the present disclosure. [Figure 5] 1 is a diagram illustrating an example of the configuration of a wireless communication system according to the present disclosure. [Figure 6] 1A and 1B are diagrams illustrating examples of the configurations of an antenna device and a base station device provided in a wireless communication system according to the present disclosure. [Figure 7] 10 is a diagram illustrating an example of the configuration of a connection antenna selection control unit provided in a base station device according to the present disclosure. [Figure 8] 10A and 10B are diagrams illustrating an example of received power measurement using a downlink reference signal by a base station device according to the present disclosure. [Figure 9] 10 is a diagram illustrating an example of received power measurement using an uplink reference signal by a base station device according to the present disclosure. [Figure 10] 10 is a diagram illustrating an example of frequency measurement using a downlink reference signal by a base station device according to the present disclosure. FIG. [Figure 11] 10 is a diagram illustrating an example of measuring a difference in Doppler frequency using an uplink signal by a base station device according to the present disclosure. FIG. [Figure 12] 10A and 10B are diagrams illustrating an example of measurement of the Doppler frequency difference using a downlink signal by a base station device according to the present disclosure. [Figure 13] FIG. 2 is a diagram illustrating a first example of an optimum antenna selection method by a base station device according to the present disclosure. [Figure 14] FIG. 10 is a diagram illustrating a second example of an optimum antenna selection method by a base station device according to the present disclosure. [Figure 15] FIG. 10 is a diagram illustrating a third example of an optimum antenna selection method by a base station device according to the present disclosure. [Figure 16] 10 is a flowchart illustrating a flow of selecting a connection antenna by a base station device according to the present disclosure. [Figure 17] 10A and 10B are diagrams illustrating an example of the effect of switching connected antennas by suppressing fluctuations in Doppler frequency, according to a base station device according to the present disclosure. [Figure 18] 10 is a diagram illustrating an example of the configuration of a connection antenna selection control unit provided in a base station device according to the present disclosure. [Figure 19] 10 is a diagram illustrating an example of measuring a propagation delay difference using an uplink signal by a base station device according to the present disclosure. FIG. [Figure 20] FIG. 10 is a diagram illustrating an example of an optimal antenna selection method using a propagation delay difference by a base station device according to the present disclosure. [Figure 21] 10 is a diagram illustrating an example of the configuration of a connection antenna selection control unit provided in a base station device according to the present disclosure. [Figure 22] 10A and 10B are diagrams illustrating an example of estimating a Doppler frequency fluctuation from a channel gain fluctuation by a base station device according to the present disclosure. [Figure 23] 10 is a diagram illustrating an example of the configuration of a connection antenna selection control unit provided in a base station device according to the present disclosure. [Figure 24] FIG. 1 is a diagram illustrating an example of the configuration of a wireless terminal according to the present disclosure. [Figure 25] 10 is a diagram illustrating an example of the configuration of a connection antenna selection control unit provided in a base station device according to the present disclosure. [Figure 26] FIG. 10 is a diagram illustrating an example of estimation of channel gain fluctuations per beam by a base station device according to the present disclosure. [Figure 27] FIG. 10 is a diagram illustrating another example of estimation of channel gain fluctuations on a per-beam basis by a base station device according to the present disclosure. [Figure 28] FIG. 10 is a diagram illustrating an example of estimation of Doppler frequency fluctuations for each beam by a base station device according to the present disclosure. [Figure 29] 10A and 10B are diagrams illustrating an example of a method for selecting an optimal antenna and an optimal beam by a base station device according to the present disclosure. [Figure 30] FIG. 2 is a block diagram illustrating an example of a hardware configuration for implementing a control function of a base station device provided in a wireless communication system according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, embodiments will be described with reference to the drawings. Note that the drawings are simplified, and the technical scope of the embodiments should not be narrowly interpreted based on the description in the drawings. Furthermore, identical elements are given the same reference numerals, and duplicate explanations will be omitted.

[0024] In the following embodiments, when necessary for convenience, the description will be divided into multiple sections or embodiments. However, unless otherwise specified, they are not unrelated to each other, and one is a partial or complete modification, application example, detailed explanation, supplementary explanation, etc. of the other. Furthermore, in the following embodiments, when the number of elements (including the number, numerical value, amount, range, etc.) is mentioned, it is not limited to that specific number, and may be more or less than the specific number, unless otherwise specified or when it is clearly limited to a specific number in principle.

[0025] Furthermore, in the following embodiments, the components (including operational steps, etc.) are not necessarily essential unless otherwise specified or considered to be clearly essential in principle. Similarly, in the following embodiments, when referring to the shape, positional relationship, etc. of components, etc., it is intended to include those that are substantially similar or approximate to the shape, etc., unless otherwise specified or considered to be clearly not essential in principle. The same applies to the above numbers, etc. (including numbers, numerical values, amounts, ranges, etc.).

[0026] <Overview of Wireless Communication System According to the Present Disclosure> 4 is a diagram illustrating an overview of a wireless communication system according to the present disclosure. In a wireless base station equipped with multiple distributed antennas and multiple APs (access points), the wireless communication system according to the present disclosure selects an antenna to be used for communication by taking into consideration both "fluctuations in received power" and "fluctuations in Doppler frequency." For example, the wireless communication system according to the present disclosure switches the antenna to be used for communication when the fluctuations in received power satisfy a predetermined condition (range) that allows switching without causing any problems, and when the fluctuations in Doppler frequency are smaller than a predetermined value.

[0027] Here, "fluctuations in received power" refers to either or both of "the difference between the channel power gain of the currently connected antenna and the channel gain of the antenna to be switched to / candidate for addition" and "changes over time in the channel power gain of the currently connected antenna."

[0028] In addition, "fluctuations in Doppler frequency" refers to either or both of "the difference between the Doppler frequency for the currently connected antenna and the Doppler frequency for the antenna to which the switchover / addition candidate will be made" and "changes over time in the Doppler frequency for the currently connected antenna."

[0029] <First Embodiment> 5 is a diagram illustrating an example of the configuration of a wireless communication system according to the present disclosure. In the present disclosure, it is assumed that wireless signals are transmitted and received between one or more antenna devices connected to a base station device (wireless base station device) and a wireless terminal (wireless terminal device).

[0030] Fig. 6 is a diagram showing an example of the configuration of an antenna device and a base station device provided in a wireless communication system according to the present disclosure. As shown in Fig. 6, the wireless communication system according to the present disclosure includes a base station device 1 and N antenna devices 2. Hereinafter, the Nth antenna device 2 will also be referred to as antenna device #N. For example, the first antenna device 2 will also be referred to as antenna device #1. The antenna device will also be referred to as a base station antenna, a base station antenna device, or simply as an antenna.

[0031] The antenna device 2 includes a digital transceiver unit 21, an RF transceiver unit 22, and one or more antenna elements 23.

[0032] The digital transceiver 21 performs modulation and demodulation of signals. For example, it performs modulation and demodulation of OFDM transmission, MIMO modulation and demodulation of radio signals transmitted and received by the multiple antenna elements 23. Part or all of the digital transceiver 21 may be provided in the base station device 1.

[0033] The RF (Radio Frequency) transceiver 22 includes an amplifier, a frequency converter, etc., and transmits and receives RF signals via the antenna element 23. The antenna device 2 may be appropriately interpreted as a distributed antenna, a TRP, an access point, an RRH (Remote Radio Head), an RU (Radio Unit), etc.

[0034] The base station device 1 includes a digital transceiver 11, a connected antenna selection controller 12, and a radio resource controller 13.

[0035] The digital transceiver 11 performs signal modulation and demodulation, similar to the digital transceiver 21 of the antenna device 2. A part or all of the digital transceiver 11 may be provided in the antenna device 2.

[0036] The connection antenna selection control unit 12 selects an antenna to be used for communication with the wireless terminal. Specifically, it estimates the fluctuations in channel power gain and Doppler frequency between the currently connected antenna and the wireless terminal, and between one or more antennas to be switched to / added and the wireless terminal, and determines the optimal connection antenna based on the estimated fluctuations in channel power gain and Doppler frequency. More specific operations will be described in detail in the following sections.

[0037] The radio resource control unit 13 specifically determines radio resources (antennas, beams, frequencies, time, etc.) to be used for each radio terminal based on the connection antenna information determined by the connection antenna selection control unit 12. The radio resource control unit 13 may also be called a scheduler unit.

[0038] 7 is a diagram illustrating an example of the configuration of a connection antenna selection control unit provided in a base station device according to the present disclosure. As shown in FIG. 7, the connection antenna selection control unit 12 provided in the base station device 1 according to the present disclosure includes a channel gain fluctuation estimation unit 121, a Doppler frequency fluctuation estimation unit 122, and an optimal antenna determination unit 123.

[0039] The channel gain fluctuation estimation unit 121 estimates the fluctuation of the channel power gain of one or more antennas including the currently connected antenna. For example, the channel power gain p s and the channel power gain p of the connected antenna m The channel power difference Δ p =p s -p m As another example, the channel power gain p m The time variation and statistics of the channel power gain p of the candidate antenna for switching / addition s The time variation and statistical values ​​of the data may be calculated. The statistical values ​​may be, for example, the mean value, variance, median value, maximum value, minimum value, percentile values ​​such as 90% value and 5% value.

[0040] p m and p s For example, as shown in FIG. 8, the received power of a downlink reference signal (e.g., SSB (Synchronization Signal Block), CSI-RS (Channel State Information Reference Signal), DMRS (Demodulation Reference Signal)) reported from the wireless terminal U1 may be the received power of the downlink reference signal.

[0041] Also, p m and p s For example, as shown in FIG. 9, p may be calculated from an uplink reference signal (for example, SRS (Sounding Reference Signal), DMRS) transmitted from the wireless terminal U1. In particular, p s It is recommended to use an uplink reference signal when measuring the uplink frequency. The uplink reference signal is periodically transmitted for communication with the antenna currently connected to the wireless terminal U1. Therefore, it is possible to measure the channel of the antenna to be switched / added without transmitting an additional reference signal. s It is possible to measure.

[0042] The Doppler frequency fluctuation estimation unit 122 estimates fluctuations in the Doppler frequency (Doppler shift) for one or more antennas including the currently connected antenna.

[0043] As an example, the Doppler frequency f s and the Doppler frequency f for the connected antenna m The absolute value of the difference Δ f =|f s -f m As another example, the Doppler frequency f m Temporal changes and statistics of Doppler frequency f for the antennas to be switched / added s The time variation and statistical values ​​of the data may be calculated. The statistical values ​​may be, for example, the mean value, variance, median value, maximum value, minimum value, percentile values ​​such as 90% value and 5% value.

[0044] f m and f s may be a measurement value using a downlink reference signal reported from a wireless terminal. m and f s may be calculated from an uplink reference signal transmitted from the wireless terminal.

[0045] For example, in the case of measurements using a downlink reference signal, the Doppler frequency may be measured by measuring the amount of phase rotation using multiple DMRS symbols that are mapped to a radio slot at different times, as shown in Figure 10. Similarly, in the case of calculations using an uplink reference signal, the Doppler frequency may be calculated by measuring the amount of phase rotation using multiple uplink reference signals that are different in time. Note that Figure 10 shows an example in which the subcarrier spacing is 120 kHz.

[0046] For example, the Doppler frequency fluctuation estimation unit 122 may calculate Δ based on the difference in the amount of phase rotation of an arbitrary uplink signal of the wireless terminal measured using the reference signals of the currently connected antenna and the candidate antenna for switching / addition, without directly measuring the absolute Doppler frequency. f may be calculated.

[0047] Specifically, as shown in FIG. 11, the Doppler frequency f m , the Doppler frequency f of the switching / addition candidate antenna s Measure Δ f =|f s -f m When calculating |, the difference in Doppler frequency between the two antennas may be calculated from the difference in the amount of phase rotation. In other words, what is measured by each antenna is the Doppler frequency f m ,f s Instead of this, the amount of phase rotation may be used.

[0048] Furthermore, when calculating the time change of the Doppler frequency for any one antenna, f m and f s Instead of directly measuring the phase rotation amount for the antenna, the change over time may be calculated by calculating the difference in the phase rotation amount for the antenna between multiple radio slots that differ in time or by calculating statistical values. Examples of statistical values ​​include the mean, variance, median, maximum value, minimum value, 90% value, 5% value, and other percentile values.

[0049] When estimating the Doppler frequency fluctuation using the downlink reference signal, the Doppler frequency fluctuation estimation unit 122 receives the Doppler frequency value f measured using the downlink reference signal for each antenna device 2 from the wireless terminal. m ,f s The Doppler frequency fluctuation estimation unit 122 may use these values ​​to estimate the fluctuation in the Doppler frequency.

[0050] Alternatively, information Δ of Doppler frequency fluctuations for one or more antenna devices 2 on the wireless terminal side f 12, the wireless terminal U1 may calculate the Doppler frequency (phase rotation amount) f m , the Doppler frequency (phase rotation) f of the downlink reference signal transmitted from the switching / addition candidate antenna s Measure Δ f =|f s -f m The difference in Doppler frequency between the two antennas may be calculated from the difference in the amount of phase rotation by |, and information on the Doppler frequency difference may be reported to the base station device.

[0051] Here, the downlink signal (downlink reference signal) used for measurement may be not only a reference signal (DMRS, etc.) included in the signal being communicated, but also a PSS (Primary Synchronization Signal), SSS (Secondary Synchronization Signal) in an SSB, or a reference signal for demodulating a broadcast channel (DMRS for PBCH).

[0052] The optimum antenna determination unit 123 selects the optimum connection antenna for the wireless terminal based on the value of the channel gain fluctuation calculated by the channel gain fluctuation estimation unit 121 and the value of the Doppler frequency fluctuation calculated by the Doppler frequency fluctuation estimation unit 122.

[0053] As an example, the channel power gain difference Δ between the two antennas calculated by the channel gain fluctuation estimation unit 121 is p and the difference Δ of the Doppler frequency between the two antennas calculated by the Doppler frequency fluctuation estimation unit 122. f Based on this, the optimum connection antenna of the wireless terminal is selected.

[0054] For example, the threshold Th corresponding to the channel power difference pand the threshold value Th corresponding to the Doppler frequency difference f The method for determining the optimum antenna using the channel power difference Δ p is the threshold Th p The larger the Doppler frequency difference Δ f is the threshold Th τ The smaller candidate antenna for switching / addition may be selected as the optimal antenna.

[0055] Figure 13 shows an example of selection when there are six candidate antennas to switch / add. f,n , Δ p,n indicates the difference in Doppler frequency and the difference in channel gain between the nth antenna among the six candidate antennas to be switched / added and the currently connected antenna.

[0056] In the example of Fig. 13, among the six candidate antennas for switching / addition, only one (Δ f,n , Δ p,n The first and fourth antennas, where Δ f,n , Δ p,n ) is located in the optimum antenna area, if the wireless terminal can communicate with the plurality of antennas, the plurality of antennas may be selected as the optimum antenna, and if the wireless terminal can communicate with only one antenna, one antenna may be selected from the plurality of antennas located in the optimum antenna area. For example, among the plurality of antennas, the antenna with the largest Doppler frequency difference Δ f It is possible to select an antenna with a smaller channel power difference Δ p An antenna with a larger

[0057] In addition, as an index of channel power, in addition to the difference in channel power between two antennas, for example, as shown in FIG. 14, the change in channel power of the candidate antenna to be switched to or its statistical value may be used to select the optimal antenna as in the example of FIG. 13.

[0058] As another example, the optimum antenna determination unit 123 determines the channel power gain difference Δ p and the temporal change Δ of the Doppler frequency for the connected antenna or the candidate antenna for switching / addition calculated by the Doppler frequency fluctuation estimation unit 122. f Based on this, the optimum connection antenna of the wireless terminal is selected.

[0059] For example, the threshold Th corresponding to the channel power difference p and a threshold Th corresponding to the change in Doppler frequency for the connected antenna. f The method for determining the optimum antenna using the channel power difference Δ p is the threshold Th p The larger the Doppler frequency change over time, Δ f is the threshold Th τ The smaller candidate antenna for switching / addition may be selected as the optimal antenna.

[0060] FIG. 15 shows an example of selection when there are two candidate antennas to switch / add. p,n indicates the difference in channel power between the nth antenna among the two candidate antennas to be switched / added and the currently connected antenna.

[0061] In the example of Fig. 15, of the two candidate antennas for switching / addition, the one (Δ f , Δ p,n ) is included, the second antenna can be selected as the optimal antenna. Note that the optimal antenna may be selected by taking into consideration not only the currently connected antenna but also the temporal change in Doppler frequency of the antenna to be switched to / added. f , Δ p,n) is located in the optimum antenna area, if the wireless terminal can communicate with multiple antennas, the multiple antennas may be selected as the optimum antenna, and if the wireless terminal can communicate with only one antenna, one antenna may be selected from the multiple antennas located in the optimum antenna area. For example, among the multiple antennas, the one with the largest Doppler frequency change Δ f It is possible to select an antenna with a smaller channel power difference Δ p An antenna with a larger

[0062] As an index of channel power, in addition to the difference in channel power between the two antennas shown in FIG. 15, the change in channel power of the antenna to be switched to / candidate for addition, or its statistical value, may be used to select the optimal antenna using a selection method similar to the example of FIG. 15 above, as in the example of FIG. 14.

[0063] Furthermore, the optimum antenna determination unit 123 notifies the radio resource control unit 13 of information (for example, antenna index) about the one or more optimum antennas that have been determined.

[0064] In the example of the optimum antenna selection method described with reference to Figs. 13 to 15, a threshold Th related to the fluctuation of the Doppler frequency is used as an example of the threshold for determining the optimum antenna area. f , the threshold Th for the variation of the channel power gain p However, there is no particular limitation to this. For example, two or more thresholds, such as an upper limit and a lower limit, may be set for each region as thresholds for each variation, and one or more ranges between these values ​​may be defined as the optimal antenna region.

[0065] Furthermore, the threshold values ​​for determining these optimal antenna regions, the ranges of the optimal antenna regions, etc. may be calculated and set in advance based on the installation positions of each antenna device 2 and a radio wave propagation model, or may be set experimentally based on prior experimental results, etc. As an example of experimental setting, they may be determined statistically based on prior experimental results, or may be determined using learning such as machine learning or deep learning, a database, etc. As a learning method, general methods such as supervised learning, unsupervised learning, and reinforcement learning may be used.

[0066] FIG. 16 shows an example of a flowchart of a connection antenna selection control method.

[0067] As described above, the wireless communication system according to the present disclosure can select, switch to, or add an antenna with high channel gain while suppressing changes in Doppler frequency when switching antennas used for communication during high-speed movement. In other words, by suppressing sudden changes in Doppler frequency (Doppler shift) when a connected antenna is switched / added, deviations in the receiving frequency at the wireless terminal or base station antenna are reduced, enabling stable communication.

[0068] The reason for this is that when switching / adding a connected antenna, not only information on channel power gain but also information on Doppler frequency fluctuations is taken into consideration. When switching a connected antenna, the connected base station antenna is switched at a timing when the Doppler frequency fluctuation before and after the switch is small, so communication can continue with the base station antenna with high channel gain while reducing the difference in reception frequency at the wireless terminal or base station antenna. When adding a connected base station antenna, the Doppler frequency difference between the multiple base station antennas with which the wireless terminal communicates is kept small, so the difference in reception frequency at the wireless terminal or base station antenna is reduced.

[0069] FIG. 17 shows an example of the effect of switching / adding a connected antenna while suppressing Doppler frequency fluctuations. For example, in FIG. 17, when a connected antenna is switched from antenna device #3 to antenna device #2 at point A for wireless terminal #1 (first wireless terminal) moving at a high speed of 90 km / h, a change in Doppler frequency of 4.5 kHz exists before and after the switching, as an example. If the beam of antenna device #4 has directionality and switching control is performed for wireless terminal #2 (second wireless terminal) based only on channel gain information, the switching point to antenna device #3 will be, for example, point B. In this case, there is a possibility that the difference in Doppler frequency before and after the switching will be 2.5 kHz, resulting in a degradation of reception performance. On the other hand, according to the present disclosure, by switching taking into account both channel gain information and Doppler frequency fluctuation information, it is possible to switch at point C, for example, and suppress degradation of reception performance.

[0070] Here, the information on the Doppler frequency fluctuation may be the difference in Doppler frequency between two antennas, or may be the temporal change in the Doppler frequency for the connected antenna (or the antenna to be switched / added). The same applies to the case of adding a connected antenna as to the case of switching.

[0071] <Embodiment 2> 18 is a diagram showing an example of the configuration of a connection antenna selection control unit provided in a base station device according to the present disclosure. As shown in FIG. 18, a connection antenna selection control unit 12a provided in a base station device 1a according to the present disclosure further includes a propagation delay variation estimation unit 124 in addition to a channel gain variation estimation unit 121, a Doppler frequency variation estimation unit 122, and an optimal antenna determination unit 123.

[0072] The propagation delay variation estimator 124 estimates the variation of the propagation delay for one or more antennas, including the currently connected antenna.

[0073] As an example, the propagation delay τ between the antenna of the candidate to be switched / added and the wireless terminal sand the propagation delay τ between the connected antenna and the wireless terminal. m The absolute value of the difference Δ τ =|τ s -τ m As another example, the propagation delay τ m The time variation and statistics of , the propagation delay τ for the antennas to be switched / added s The time variation and statistical values ​​of the data may be calculated. The statistical values ​​may be, for example, the mean value, variance, median value, maximum value, minimum value, percentile values ​​such as 90% value and 5% value.

[0074] τ m and τ s may be a measurement value using a downlink reference signal reported from a wireless terminal. m and τ s may be calculated from an uplink reference signal transmitted from the wireless terminal.

[0075] Also, τ m and τ s Without directly measuring Δ τ Specifically, as shown in FIG. 19, the wireless terminal U1 may calculate the reception time t m , the reception time t at the antenna of the candidate for switching / addition s Measure Δ τ =|t s -t m The propagation delay difference may be calculated by |

[0076] The optimum antenna determination unit 123 calculates the channel gain fluctuation value Δ p and the value Δ of the Doppler frequency fluctuation calculated by the Doppler frequency fluctuation estimation unit 122. f In addition, the propagation delay variation value Δ calculated by the propagation delay variation estimation unit 124 τBased on the value of , the optimum connection antenna for the wireless terminal is selected.

[0077] As an example of a method for determining the optimum antenna, a threshold Th corresponding to the channel power difference is used. p and the threshold value Th corresponding to the Doppler frequency difference f In addition, a threshold Th corresponding to the propagation delay difference is τ A method for determining the optimum antenna will be described below. p is the threshold Th p Larger, propagation delay difference Δ τ is the threshold Th τ The smaller candidate antenna for switching / addition may be selected as the optimal antenna.

[0078] Figure 20 shows an example of selection when there are six candidate antennas to switch / add. τ,n indicates the propagation delay difference between the nth antenna among the six candidate antennas to be switched / added and the currently connected antenna.

[0079] In the example of Fig. 20, among the six candidate antennas for switching / addition, only one (Δ f,n , Δ τ,n , Δ p,n The first and fourth antennas, where Δ f,n ,Δ τ,n , Δ p,n ) is located in the optimum antenna area, if the wireless terminal can communicate with multiple antennas, multiple antennas may be selected as the optimum antenna, and if the wireless terminal can communicate with only one antenna, one antenna may be selected from the multiple antennas located in the optimum antenna area. For example, among the multiple antennas, the antenna with the greatest propagation delay difference Δ τ It is possible to select an antenna with a smaller Doppler frequency difference Δ f It is possible to select an antenna with a smaller channel power difference Δ p An antenna with a larger

[0080] Furthermore, the optimum antenna determination unit 123 notifies the radio resource control unit 13 of information (for example, antenna index) about the one or more optimum antennas that have been determined.

[0081] <Third Embodiment> Fig. 21 is a diagram showing an example of the configuration of a connection antenna selection control unit provided in a base station device according to the present disclosure. As shown in Fig. 21, a connection antenna selection control unit 12b provided in a base station device 1b according to the present disclosure includes a channel gain fluctuation estimator 121, a Doppler frequency fluctuation estimator 122, and an optimal antenna determiner 123. In the connection antenna selection control unit 12b, the Doppler frequency fluctuation estimator 122 may estimate a Doppler frequency fluctuation using information on the channel gain fluctuation calculated by the channel gain fluctuation estimator 121.

[0082] The Doppler frequency fluctuation estimation unit 122 estimates fluctuations in the Doppler frequency (Doppler shift) for one or more antennas including the currently connected antenna.

[0083] As an example, the Doppler frequency f s and the Doppler frequency f for the connected antenna m The absolute value of the difference Δ f =|f s -f m As another example, the Doppler frequency f m Temporal changes and statistics of Doppler frequency f for the antennas to be switched / added s It is also possible to calculate the time-dependent changes and statistical values ​​of the above.

[0084] Here, the Doppler frequency fluctuation estimating unit 122 may estimate the fluctuation of the Doppler frequency using information on the channel gain fluctuation calculated by the channel gain fluctuation estimating unit 121 .

[0085] For example, as shown in Fig. 22, the fluctuation of channel gain can be modeled from the positional relationship between the antenna device and the wireless terminal, and the phase relationship between the direct wave and the ground reflected wave. Similarly, the Doppler frequency can also be modeled from the relationship between the direction of the moving path between the antenna device and the wireless terminal, the moving speed, etc. Therefore, the Doppler frequency and its fluctuation can be estimated based on information on the fluctuation of channel gain and information on the movement of the wireless terminal.

[0086] The above estimation may involve estimating the Doppler frequency by calculation based on information modeled from theoretical formulas of a radio wave propagation model, or may involve experimental statistical estimation using learning methods such as machine learning or deep learning, or a database. When learning is used, for example, estimation may be performed using supervised learning such as CNN or LSTM, in which information on channel gain fluctuations is used as input and information capable of estimating the Doppler frequency or its fluctuations (including wireless terminal information such as wireless terminal position information and moving speed information) is used as the teacher label and output. CNN stands for Convolutional Neural Network. LSTM stands for Long Short-Term Memory. Statistical values ​​include, for example, the mean, variance, median, maximum value, minimum value, and percentile values ​​such as the 90th percentile and 5th percentile.

[0087] <Fourth Embodiment> 23 is a diagram showing an example of the configuration of a connection antenna selection control unit provided in a base station device according to the present disclosure. As shown in Fig. 23, a connection antenna selection control unit 12c provided in a base station device 1c according to the present disclosure further includes a compensation parameter calculation unit 125 in addition to a channel gain fluctuation estimation unit 121, a Doppler frequency fluctuation estimation unit 122, and an optimal antenna determination unit 123.

[0088] When two or more base station antennas are selected by the optimum antenna determination unit 123, the compensation parameter calculation unit 125 determines compensation parameters for the transmission and reception frequencies (Doppler shift amount) based on the determined base station antenna information, channel gain information, and frequency measurement information.

[0089] As one example, the compensation parameter in the uplink may be information for determining the transmission frequency (amount of Doppler shift) of the wireless terminal. As another example, the compensation parameter in the downlink may be information for determining the reception frequency (amount of Doppler shift) of the wireless terminal.

[0090] Here, an example will be described in which base station antennas #1, #2, and #3 are selected by the optimum antenna determination unit 123. If the Doppler frequencies of the base station antennas #1, #2, and #3 are f1, f2, and f3, respectively, the compensation parameter F f The calculation method may be, for example, as shown in the following equation (1), where the Doppler frequency is a weighted average of the Doppler frequencies for each base station antenna selected by the optimum antenna determination unit 123.

[0091]

number

[0092] The weighting coefficient w n may be determined based on the channel power gain of each base station antenna. If the channel power gains of base station antennas #1, #2, and #3 are p1, p2, and p3, respectively, the compensation parameter F f may be given by the following equation (2):

[0093]

number

[0094] The calculated compensation parameters are notified to the wireless terminal, and the wireless terminal performs compensation of the transmission and reception frequencies based on the notified compensation parameters. For example, the compensation parameters may be included in a Transmission Configuration Indication (TCI) state notified from the base station to the wireless terminal. As another example, the compensation parameters may be notified to the wireless terminal using Radio Resource Control (RRC) signaling, a Media Access Control (MAC) CE (Media Access Control) or Downlink Control Information (DCI).

[0095] When a wireless terminal simultaneously communicates with base station antennas #1, #2, and #3, if the Doppler frequency compensation is performed by focusing only on the Doppler frequency f1 of base station antenna #1, the Doppler frequencies of base station antennas #2 and #3 are not taken into consideration, and serious reception timing errors may occur in the base station antennas or the wireless terminal. f By compensating the transmission and reception frequencies based on this, it is possible to compensate for the different Doppler frequencies of multiple base station antennas on an average basis and reduce errors in the reception frequency. In addition, for example, weighting based on the channel power gain allows prioritizing Doppler frequency compensation according to the channel gain.

[0096] <Fifth Embodiment> 24 is a diagram illustrating an example of the configuration of a wireless terminal (wireless terminal device) according to the present disclosure. As shown in FIG. 24, a wireless terminal U1 includes one or more antenna elements 31, an RF transceiver unit 32, a digital transceiver unit 33, and a control unit 34.

[0097] The RF (Radio Frequency) transceiver 32 includes an amplifier, a frequency converter, etc., and transmits and receives RF signals via the antenna elements 31. The digital transceiver 33 performs signal modulation and demodulation, etc. For example, it performs modulation and demodulation for OFDM transmission, MIMO modulation and demodulation of radio signals transmitted and received by multiple antenna elements, etc. The control unit 34 performs control during radio transmission and reception, for example, transmission power control, reception timing control, automatic frequency control, handover control, beam control, etc. The control unit 34 further includes a compensation parameter calculation unit 341.

[0098] When two or more base station antennas are selected by the optimum antenna determination unit 123 of the base station device 1, the compensation parameter calculation unit 341 determines compensation parameters for the transmission and reception frequencies (Doppler shift) based on the determined base station antenna information, channel gain information, and frequency measurement information.

[0099] As one example, the compensation parameter in the uplink may be information for determining the transmission frequency (amount of Doppler shift) of the wireless terminal. As another example, the compensation parameter in the downlink may be information for determining the reception frequency (amount of Doppler shift) of the wireless terminal.

[0100] The method for calculating the compensation parameter may be, for example, a weighted average of the Doppler frequencies of each base station antenna selected by the optimum antenna determination unit 123, as in the above-mentioned equation (1), and the weighting coefficient may be determined based on the channel power gain of each base station antenna, as in the above-mentioned equation (2).

[0101] In this embodiment, the connection antenna selection control unit 12 may also have a function of notifying the wireless terminal U1 of the determined optimum antenna information. For example, the optimum antenna information may be included in the TCI status notified to the wireless terminal U1 from the base station. The TCI status may be included in, for example, the MAC CE or DCI.

[0102] Furthermore, the information on the Doppler frequency and the channel power gain may be notified by the base station antenna or may be measured by the wireless terminal U1.

[0103] <Sixth Embodiment> 25 is a diagram showing an example of the configuration of a connection antenna selection control unit provided in a base station device according to the present disclosure. As shown in FIG. 23, a connection antenna selection control unit 12d provided in a base station device 1d according to the present disclosure includes a channel gain fluctuation estimation unit 121 and a Doppler frequency fluctuation estimation unit 122, and includes an optimal antenna beam determination unit 126 instead of the optimal antenna determination unit 123.

[0104] The channel gain fluctuation estimation unit 121 estimates the fluctuation of the channel power gain for each analog beam of one or more base station antennas including the currently connected base station antenna.

[0105] As an example, as shown in FIG. 26, when a wireless terminal U1 receives an analog beam #b m If connected to, the analog beam #b of the base station antenna #s that is a candidate for switching / addition s Channel power gain when in use p s,bs and the analog beam #b of the connected base station antenna #m. m The channel power gain p m,bm The channel power difference Δ p,s,bs =p s,bs -p m,bm However, if the base station antenna can use multiple analog beam codebooks as shown in Figure 27, s = m, that is, the channel power fluctuation may be calculated for different beams of the currently connected base station antenna. As another example, the time variation or statistical value of the channel gain may be calculated. Examples of statistical values ​​include the mean, variance, median, maximum value, minimum value, 90th percentile value, 5th percentile value, etc.

[0106] The Doppler frequency fluctuation estimation unit 122 estimates the fluctuation of the Doppler frequency for each analog beam of one or more base station antennas, including the currently connected base station antenna.

[0107] As an example, as shown in FIG. 28, when a wireless terminal U1 receives an analog beam #b of a base station antenna #m, m If connected to, the analog beam #b of the base station antenna #s that is a candidate for switching / addition s Doppler frequency f s,bs and the analog beam #b of the connected base station antenna #m. m Doppler frequency f m、bm The absolute value of the difference Δ f =|f s,bs -f m、bm | is calculated. However, as in the example described in FIG. 27, if the base station antenna can use multiple analog beam codebooks, s = m, that is, the Doppler frequency fluctuations may be calculated for different beams of the currently connected base station antenna. As another example, the temporal change in Doppler frequency or statistical values ​​may be calculated. Examples of statistical values ​​include the mean, variance, median, maximum value, minimum value, 90% value, 5% value, and other percentile values.

[0108] The optimal antenna / beam determination unit 126 selects the optimal connecting base station antenna and analog beam for the wireless terminal based on the value of the channel gain fluctuation for each analog beam calculated by the channel gain fluctuation estimation unit 121 and the value of the Doppler frequency fluctuation for each analog beam calculated by the Doppler frequency fluctuation estimation unit 122.

[0109] For example, the channel power gain difference Δ between the two beams calculated by the channel gain fluctuation estimation unit 121 p and the difference Δ of the Doppler frequency between the two beams calculated by the Doppler frequency fluctuation estimation unit 122. f 13, the optimum base station antenna and analog beam for the wireless terminal are selected. As an example, as shown in FIG. 29, the threshold Th corresponding to the channel power difference is used. p and the threshold value Th corresponding to the Doppler frequency difference f may be used to determine the optimal base station antenna and analog beam.

[0110] Although the processing units shown in Figures 5 to 15, 18, 21, 23, 25, etc. are described as parts of an antenna device or a base station device, the present invention is not limited to this. Some or all of the processing units in the figures may be implemented anywhere in the RU (Radio Unit), DU (Distributed Unit), or CU (Center Unit) of the radio base station, or may be implemented in an external device such as a RAN Intelligent Controller (RIC), which is a control device other than the radio base station. Note that, as in the example shown in Figure 12, some of the functions of the processing units may be implemented on the radio terminal side.

[0111] In addition, the technology can be applied not only to wireless communications in the millimeter wave, centimeter wave, and frequency bands below 6 GHz known as Sub6, but also to terahertz wave (sub-terahertz wave) communications, optical space communications (free space optical communications), and visible light communications (optical wireless communications).

[0112] (Hardware configuration for realizing the antenna selection function of the base station device according to the present disclosure) The antenna selection process (control process) performed by the base station device according to the present disclosure can be realized by a general-purpose computer system, which will be briefly described below with reference to FIG.

[0113] 30 is a block diagram showing an example of a hardware configuration for realizing the antenna selection function of a base station device according to the present disclosure. Computer 300 includes, for example, a central processing unit (CPU) 301, which is a control device, a random access memory (RAM) 302, and a read only memory (ROM) 303. Computer 300 further includes an interface (IF) 304, which is an interface with the outside, and a hard disk drive (HDD) 305, which is an example of a non-volatile storage device. Computer 300 may also include input devices such as a keyboard and a mouse, and a display device such as a display, as other components not shown.

[0114] The HDD 305 stores an operating system (OS) (not shown) and a control program 306. The control program 306 is a computer program that implements the antenna selection process of the base station device according to the present disclosure.

[0115] The CPU 301 controls various processes in the computer 300, access to the RAM 302, the ROM 303, the IF 304, and the HDD 305, etc. In the computer 300, the CPU 301 reads and executes the OS and the control program 306 stored in the HDD 305. In this way, the computer 300 realizes the antenna selection function of the base station device according to the present disclosure.

[0116] The above-mentioned program includes instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more functions described in this disclosure. The program may be stored on a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable medium or tangible storage medium includes RAM, ROM, flash memory, solid-state drive (SSD) or other memory technology, CD-ROM, digital versatile disc (DVD), Blu-ray disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device. The program may also be transmitted on a transitory computer-readable medium or communication medium. By way of example and not limitation, transitory computer-readable medium or communication medium includes electrical, optical, acoustic, or other forms of propagated signals.

[0117] In the present disclosure, a case has been described in which the antenna selection process implemented by the base station device is implemented by a general-purpose computer system, but the Doppler frequency variation information estimation process implemented by the wireless terminal (wireless terminal device) according to the present disclosure can also be implemented by a general-purpose computer system. In a hardware configuration that realizes the Doppler frequency variation information estimation function of the wireless terminal device according to the present disclosure, the control program 306 of the computer 300 shown in Fig. 30 is a computer program that implements the Doppler frequency variation information estimation process of the wireless terminal device, instead of a computer program that implements the antenna selection process of the base station device.

[0118] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0119] Each drawing is merely an example for describing one or more embodiments. Each drawing may relate not only to one particular embodiment, but also to one or more other embodiments. As will be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings to create, for example, an embodiment not explicitly shown or described. Not all features or steps shown in any one drawing are necessary to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0120] Furthermore, some or all of the above-described embodiments can be described as, but are not limited to, the following supplementary notes.

[0121] (Appendix 1) a channel gain fluctuation estimation unit that estimates information on channel power gain fluctuations of one or more antennas including a currently connected antenna; a Doppler frequency fluctuation estimation unit that estimates information on Doppler frequency fluctuations for one or more antennas including a currently connected antenna; an optimal antenna determination unit that selects one or more optimal connection antennas for the wireless terminal based on the information on the channel power gain fluctuation and the information on the Doppler frequency fluctuation; A wireless base station device comprising:

[0122] (Appendix 2) The Doppler frequency fluctuation estimation unit calculates, as the information of the Doppler frequency fluctuation, a Doppler frequency difference between a Doppler frequency for a switching destination / candidate antenna and a Doppler frequency for a currently connected antenna, or / and calculates a time variation or a statistical value of the Doppler frequency for the currently connected antenna and / or the switching destination / candidate antenna. 2. The wireless base station device according to claim 1.

[0123] (Appendix 3) the channel gain fluctuation estimation unit calculates, as the information of the channel power gain fluctuation, a channel power difference between a channel power gain of a switching destination / candidate antenna and a channel power gain of a currently connected antenna, or / and calculates a time variation or a statistical value of the channel power gain of the currently connected antenna and / or the switching destination / candidate antenna. 3. The wireless base station device according to claim 1 or 2.

[0124] (Appendix 4) the Doppler frequency fluctuation estimation unit estimates the Doppler frequency fluctuation using information on the channel power gain fluctuation as information on the Doppler frequency fluctuation. 4. The wireless base station device according to claim 1.

[0125] (Appendix 5) the Doppler frequency fluctuation estimation unit estimates the Doppler frequency fluctuation information using a received signal of an uplink reference signal from a wireless terminal received by a plurality of antenna devices. 4. The wireless base station device according to claim 1.

[0126] (Appendix 6) the Doppler frequency fluctuation estimation unit uses information on Doppler frequency differences for a plurality of antenna devices reported from a wireless terminal to a base station device as information on the Doppler frequency fluctuation. 4. The wireless base station device according to claim 1.

[0127] (Appendix 7) The information on the Doppler frequency difference reported from the wireless terminal is estimated from downlink reference signals received by the wireless terminal and transmitted from a plurality of antenna devices. 7. The wireless base station device according to claim 6.

[0128] (Appendix 8) the Doppler frequency fluctuation estimation unit estimates the Doppler frequency fluctuation information by learning or a database using wireless terminal information and channel power gain information of the wireless terminal previously acquired by the base station device. 5. The wireless base station device according to claim 1.

[0129] (Appendix 9) the optimum antenna determination unit defines an optimum antenna area based on a range of values ​​of the channel power gain fluctuation and a range of values ​​of the Doppler frequency fluctuation, and selects one or more antennas included in the optimum antenna area as optimum connection antennas for the wireless terminal. 9. The wireless base station device according to any one of Supplementary notes 1 to 8.

[0130] (Appendix 10) the optimum antenna determination unit statistically defines an optimum antenna area using experimental learning or a database from the range of values ​​of the channel power gain fluctuation and the range of values ​​of the Doppler frequency fluctuation, and selects one or more antennas included in the optimum antenna area as optimum connection antennas for the wireless terminal. 10. The wireless base station device according to any one of Supplementary notes 1 to 9.

[0131] (Appendix 11) the optimum antenna determination unit selects one or more optimum connection antennas using information on a Doppler frequency difference between a Doppler frequency for a switching destination / addition candidate antenna and a Doppler frequency for a currently connected antenna as the information on the Doppler frequency fluctuation. 11. The wireless base station device according to claim 1.

[0132] (Appendix 12) The optimum antenna determination unit selects one or more optimum connection antennas using, as the information on the Doppler frequency fluctuation, a time variation or a statistical value of the Doppler frequency of the currently connected antenna and / or the antenna to be switched to / added. 12. The wireless base station device according to claim 1.

[0133] (Appendix 13) the optimum antenna determination unit selects one or more optimum connection antennas using, as the information on the channel power gain fluctuation, information on a channel power difference between a channel power gain of a switching destination / addition candidate antenna and a channel power gain of a connected antenna, or / and time-varying changes or statistics of the channel power gains of the connected antenna and / or the switching destination / addition candidate antenna. 13. The wireless base station device according to claim 1.

[0134] (Appendix 14) The wireless communication system further includes a propagation delay variation estimation unit that estimates information about a propagation delay variation for one or more antennas including a currently connected antenna, The optimum antenna determination unit selects the optimum connection antenna by also using information on the propagation delay variation. 14. The wireless base station device according to claim 1.

[0135] (Appendix 15) The propagation delay variation estimation unit calculates, as the information of the propagation delay variation, a propagation delay difference between a propagation delay between a switching destination / addition candidate antenna and the wireless terminal and a propagation delay between a currently connected antenna and the wireless terminal, or / and calculates a time variation or a statistical value of the propagation delay between the currently connected antenna and / or the switching destination / addition candidate antenna and the wireless terminal. 15. The wireless base station device according to claim 14.

[0136] (Appendix 16) the optimum antenna determination unit defines an optimum antenna area based on a range of values ​​of the channel power gain fluctuation, a range of values ​​of the Doppler frequency fluctuation, and a range of values ​​of the propagation delay fluctuation, and selects one or more antennas included in the optimum antenna area as optimum connection antennas for the wireless terminal. 16. The wireless base station device according to claim 14 or 15.

[0137] (Appendix 17) a correction parameter calculation unit that determines a Doppler frequency correction value based on the optimum antenna information determined by the optimum antenna determination unit and information on Doppler frequencies for one or more connected antennas; The Doppler frequency correction value determined by the correction parameter calculation unit is reported to the wireless terminal. 17. The wireless base station device according to any one of Supplementary notes 1 to 16.

[0138] (Appendix 18) the Doppler frequency correction value is a weighted average of the Doppler frequencies of the one or more base station antennas; 18. The wireless base station device according to claim 17.

[0139] (Appendix 19) the weighted average of Doppler frequencies is weighted by weighting factors calculated using channel power gains of the one or more base station antennas; 19. The wireless base station apparatus according to claim 18.

[0140] (Appendix 20) the radio base station device uses one or more beams for each antenna, and the channel gain fluctuation estimator, the Doppler frequency fluctuation estimator, and the optimum antenna determiner operate taking into account the one or more beams. 20. The wireless base station device according to any one of Supplementary notes 1 to 19.

[0141] (Appendix 21) A part or all of each processing unit is provided in an external control device. 20. The wireless base station device according to any one of Supplementary notes 1 to 19.

[0142] (Appendix 22) The method is characterized by receiving downlink reference signals from one or more base station antennas including the currently connected antenna, and estimating information on Doppler frequency fluctuations including information on Doppler frequency differences for multiple antennas and / or time-varying and statistical values ​​of Doppler frequencies for one or more antennas. Wireless terminal device.

[0143] (Appendix 23) and reporting the information on the Doppler frequency fluctuation to a base station device. 23. The wireless terminal device of claim 22.

[0144] (Appendix 24) determining a Doppler frequency offset value using Doppler frequencies of one or more base station antennas including the currently connected base station antenna, which are measured or reported by the base station, and correcting the transmission and reception frequencies based on the Doppler frequency offset value; 24. The wireless terminal device according to claim 22 or 23.

[0145] (Appendix 25) the Doppler frequency correction value is a weighted average of the Doppler frequencies of the one or more base station antennas; 25. The wireless terminal device of claim 24.

[0146] (Appendix 26) the weighted average of Doppler frequencies is weighted by weighting factors calculated using channel power gains of the one or more base station antennas; 26. The wireless terminal device of claim 25.

[0147] (Appendix 27) The wireless base station device Estimating channel power gain variation information for one or more antennas including the currently connected antenna; estimating Doppler frequency variation information for one or more antennas, including the currently connected antenna; selecting one or more optimal connection antennas for the wireless terminal based on the channel power gain variation information and the Doppler frequency variation information; Control method.

[0148] (Appendix 28) estimating channel power gain fluctuation information of one or more antennas including a currently connected antenna; estimating Doppler frequency variation information for one or more antennas, including the currently connected antenna; selecting one or more optimal connection antennas for a wireless terminal based on the channel power gain variation information and the Doppler frequency variation information; A control program that causes a computer to execute the above.

[0149] (Appendix 29) The wireless terminal device receiving a downlink reference signal from one or more base station antennas including a currently connected antenna; estimating Doppler frequency difference information for multiple antennas and / or Doppler frequency variation information, including time-varying and statistical information for Doppler frequency for one or more antennas; Control method.

[0150] (Appendix 30) receiving a downlink reference signal from one or more base station antennas including a currently connected antenna; estimating Doppler frequency differences for multiple antennas and / or Doppler frequency variation information, including information on the time evolution and statistics of Doppler frequencies for one or more antennas; A control program that causes a computer to execute the above.

[0151] Some or all of the elements (e.g., configurations and functions) described in Supplementary Notes 2 to 21 that are dependent on Supplementary Notes 1 may also be dependent on Supplements 27 and 28 in the same dependency relationship as Supplementary Notes 2 to 21. Also, some or all of the elements (e.g., configurations and functions) described in Supplementary Notes 23 to 26 that are dependent on Supplementary Notes 22 may also be dependent on Supplements 29 and 30 in the same dependency relationship as Supplementary Notes 23 to 26. Some or all of the elements described in any Supplementary Note may be applicable to various hardware, software, recording means for recording software, systems, and methods. [Explanation of symbols]

[0152] 1 Base station equipment (wireless base station equipment) 2 Antenna device 11 Digital transmitter / receiver 12 Connection antenna selection control section 13 Radio Resource Control Unit 21 Digital transmitter / receiver 22 RF transceiver 23 Antenna element 31 Antenna element 32 RF transceiver 33 Digital Transmitter / Receiver 34 Control Unit 121 Channel gain fluctuation estimation unit 122 Doppler frequency fluctuation estimation unit 123 Optimal Antenna Determination Unit 124 Propagation delay variation estimation unit 125 Compensation parameter calculation unit 126 Optimal Antenna Beam Determination Unit 300 Computers 301 CPU 302 RAM 303 ROM 304 IF 305 HDD 306 Control Program 341 Compensation parameter calculation unit U1 Wireless terminal (wireless terminal device)

Claims

1. a channel gain fluctuation estimation unit that estimates information on channel power gain fluctuations of one or more antennas including a currently connected antenna; a Doppler frequency fluctuation estimation unit that estimates information on Doppler frequency fluctuations for one or more antennas including a currently connected antenna; an optimal antenna determination unit that selects one or more optimal connection antennas for the wireless terminal based on the information on the channel power gain fluctuation and the information on the Doppler frequency fluctuation; A wireless base station device comprising:

2. the Doppler frequency fluctuation estimation unit calculates, as the information on the Doppler frequency fluctuation, a Doppler frequency difference between a Doppler frequency for the antenna to be switched to / candidate for addition and a Doppler frequency for the currently connected antenna, or / and calculates a time variation or a statistical value of the Doppler frequency for the currently connected antenna and / or the antenna to be switched to / candidate for addition. The radio base station device according to claim 1 .

3. the channel gain fluctuation estimation unit calculates, as the information of the channel power gain fluctuation, a channel power difference between a channel power gain of a target / candidate antenna and a channel power gain of a currently connected antenna, or / and calculates a time variation or a statistical value of the channel power gain of the currently connected antenna and / or the target / candidate antenna. The radio base station device according to claim 1 .

4. the Doppler frequency fluctuation estimation unit estimates the Doppler frequency fluctuation using information on the channel power gain fluctuation as information on the Doppler frequency fluctuation. The radio base station device according to claim 1 .

5. the Doppler frequency fluctuation estimation unit estimates the Doppler frequency fluctuation information using a received signal of an uplink reference signal from a wireless terminal received by a plurality of antenna devices. The radio base station device according to claim 1 .

6. the Doppler frequency fluctuation estimation unit uses information on Doppler frequency differences for a plurality of antenna devices reported from a wireless terminal to a base station device as the information on the Doppler frequency fluctuation. The radio base station device according to claim 1 .

7. The information on the Doppler frequency difference reported from the wireless terminal is estimated from downlink reference signals received by the wireless terminal and transmitted from a plurality of antenna devices. The radio base station device according to claim 6.

8. the Doppler frequency fluctuation estimation unit estimates the Doppler frequency fluctuation information by learning or a database using wireless terminal information and channel power gain information of the wireless terminal previously acquired by the base station device. The radio base station device according to claim 1 .

9. the optimum antenna determination unit defines an optimum antenna area based on a range of values ​​of the channel power gain fluctuation and a range of values ​​of the Doppler frequency fluctuation, and selects one or more antennas included in the optimum antenna area as optimum connection antennas for the wireless terminal. The radio base station device according to claim 1 .

10. the optimum antenna determination unit statistically defines an optimum antenna area using experimental learning or a database from the range of values ​​of the channel power gain fluctuation and the range of values ​​of the Doppler frequency fluctuation, and selects one or more antennas included in the optimum antenna area as optimum connection antennas for the wireless terminal. The radio base station device according to claim 1 .

11. the optimum antenna determination unit selects one or more optimum connection antennas using information on a Doppler frequency difference between a Doppler frequency for a switching destination / addition candidate antenna and a Doppler frequency for a currently connected antenna as the information on the Doppler frequency fluctuation. The radio base station device according to claim 1 .

12. the optimum antenna determination unit selects one or more optimum connection antennas using, as the information on the Doppler frequency fluctuation, time-varying changes or statistical values ​​of Doppler frequencies for the currently connected antenna and / or the antenna to be switched to / added as a candidate. The radio base station device according to claim 1 .

13. the optimum antenna determination unit selects one or more optimum connection antennas using, as the information on the channel power gain fluctuation, information on a channel power difference between a channel power gain of a switching destination / addition candidate antenna and a channel power gain of a connected antenna, or / and time-varying changes or statistics of the channel power gains of the connected antenna and / or the switching destination / addition candidate antenna. The radio base station device according to claim 1 .

14. a propagation delay variation estimation unit that estimates information on propagation delay variations for one or more antennas including a currently connected antenna; The optimum antenna determination unit selects the optimum connection antenna by also using information on the propagation delay variation. The radio base station device according to claim 1 .

15. The propagation delay variation estimation unit calculates, as the information of the propagation delay variation, a propagation delay difference between a propagation delay between a target / candidate antenna and the wireless terminal and a propagation delay between a currently connected antenna and the wireless terminal, or / and calculates a time variation or a statistical value of the propagation delay between the currently connected antenna and / or the target / candidate antenna and the wireless terminal. The radio base station device according to claim 14.

16. the optimum antenna determination unit defines an optimum antenna area based on a range of values ​​of the channel power gain fluctuation, a range of values ​​of the Doppler frequency fluctuation, and a range of values ​​of the propagation delay fluctuation, and selects one or more antennas included in the optimum antenna area as optimum connection antennas for the wireless terminal. The radio base station device according to claim 14.

17. a correction parameter calculation unit that determines a Doppler frequency correction value based on the optimum antenna information determined by the optimum antenna determination unit and information on the Doppler frequencies for one or more of the base station antennas; The Doppler frequency correction value determined by the correction parameter calculation unit is reported to the wireless terminal. The radio base station device according to claim 1 .

18. the Doppler frequency correction value is a weighted average of the Doppler frequencies of the one or more base station antennas; The radio base station device according to claim 17.

19. the weighted average of Doppler frequencies is weighted by weighting factors calculated using channel power gains of the one or more base station antennas; The radio base station device according to claim 18.

20. the radio base station device uses one or more beams for each antenna, and the channel gain fluctuation estimator, the Doppler frequency fluctuation estimator, and the optimum antenna determiner operate taking into account the one or more beams. The radio base station device according to claim 1 .

21. A part or all of each processing unit is provided in an external control device. The radio base station device according to claim 1 .

22. The method is characterized in that it receives downlink reference signals from one or more base station antennas including the currently connected antenna, and estimates information on Doppler frequency fluctuations including information on Doppler frequency differences for multiple antennas and / or time-varying and statistical values ​​of Doppler frequencies for one or more antennas. Wireless terminal device.

23. and reporting the information on the Doppler frequency fluctuation to a base station device.

23. The wireless terminal device of claim 22.

24. determining a Doppler frequency offset value using Doppler frequencies of one or more base station antennas including a currently connected base station antenna, which are measured or reported by the base station, and correcting the transmission and reception frequencies based on the Doppler frequency offset value; 23. The wireless terminal device of claim 22.

25. the Doppler frequency correction value is a weighted average of the Doppler frequencies of the one or more base station antennas; 25. The wireless terminal device of claim 24.

26. the weighted average of Doppler frequencies is weighted by weighting factors calculated using channel power gains of the one or more base station antennas; 26. The wireless terminal device of claim 25.

27. A wireless base station device estimating channel power gain fluctuation information for one or more antennas including the currently connected antenna; estimating Doppler frequency variation information for one or more antennas, including the currently connected antenna; selecting one or more optimal connection antennas for the wireless terminal based on the channel power gain variation information and the Doppler frequency variation information; Control method.

28. estimating channel power gain variation information of one or more antennas including the currently connected antenna; estimating Doppler frequency variation information for one or more antennas, including the currently connected antenna; selecting one or more optimal connection antennas for a wireless terminal based on the channel power gain variation information and the Doppler frequency variation information; A control program that causes a computer to execute the above.

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