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

Abstract

To provide a radio base station apparatus, a radio terminal apparatus, a control method, 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 base station antenna, a propagation delay variation estimation unit that estimates information on a propagation delay variation for the one or more antennas including the connected base station 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 propagation delay 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] Mobile communication systems such as cellular systems are undergoing technological development and specification formulation to achieve various performance requirements, including high-speed, high-capacity communication, low latency, and high reliability. In macrocell systems, a related technology, the cell radius is large, and user terminals located at the cell edge are far from the base station, resulting in low received power and strong interference from neighboring cells, resulting in poor communication quality. To address these issues, technologies that utilize multiple base station antennas / cells / TRPs (hereinafter referred to as base station antennas) installed at relatively high densities and enable cooperative operation (e.g., Coordinated Multi-Point (CoMP), Multi-TRP, Distributed MIMO) have been put into practical use or have been considered.

[0003] In this system, a user terminal communicates with one or more base station antennas located in the vicinity. When the user terminal moves within the system, the base station antennas with which it communicates can be switched or added depending on 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 the user terminal, it is essential to select an appropriate base station antenna.

[0004] Furthermore, maintaining high communication quality requires accurate synchronization between the base station antenna and the user terminal. In the downlink of a Time Division Duplex (TDD) system, the user terminal typically measures the propagation delay between the base station antenna and the user 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 user terminal via a Random Access Channel (RACH) procedure between the user terminal and the base station, and the user terminal transmits uplink signals at the timing specified by the TA command. By each user terminal transmitting according to its respective notified TA, the time at which the base station antenna receives signals is synchronized between users.

[0005] 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 base station antenna and the switching candidate base station antenna 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 base station antenna based on the RSRP difference, it is possible to continue selecting the base station antenna with the highest gain.

[0006] 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.

[0007] While the technology described in Non-Patent Document 1 allows for the continuous selection of a base station antenna with a high channel gain, it does not take into account changes in radio wave propagation delay due to base station antenna switching. For example, as shown in Figure 2, if there is a large difference between the propagation delay τ2 between the currently connected base station antenna #2 and the user terminal and the propagation delay τ1 between the switched-to base station antenna #1 and the user terminal (|τ1-τ2|≫0), a signal reception timing error may occur immediately after switching the base station antenna. The reception timing error occurs when the user terminal receives the signal in the downlink and when the base station antenna receives the signal in the uplink. The reception timing error can cause various problems.

[0008] For example, in an Orthogonal Frequency Division Multiplexing (OFDM) system, a large deviation in reception timing exceeding the CP (Cyclic Prefix) length in OFDM can cause interference between OFDM symbols and between subcarriers, resulting in interference between user terminals and base stations and serious degradation of communication quality.

[0009] Even if the deviation in reception timing does not exceed the CP length, the deviation in reception timing can cause a change in the signal phase in the frequency domain, resulting in fluctuations in the channel coefficients. In wireless communication systems, channel estimation is sometimes performed in units of one or more resource blocks (RBs). When the signal phase varies in the frequency domain, the channel coefficients vary significantly for each subcarrier within the RB. Therefore, the channel estimation method described above generates significant channel estimation errors, resulting in degradation of communication quality. It is possible to estimate the channel for each subcarrier, assuming a change in the signal phase in the frequency domain. However, this reduces the effect of averaging noise in the frequency domain, which may actually degrade the accuracy of channel estimation. Furthermore, channel estimation for each subcarrier is undesirable from the perspective of processing load.

[0010] Patent Document 1 discloses a synchronization method using the RACH procedure as a method for establishing synchronization with a base station antenna other than the currently connected base station antenna in the uplink of a system in which a user terminal communicates with multiple base station antennas. As shown in Fig. 3, while communicating with the currently connected base station antenna #2, the user terminal performs random access to the base station antenna #1 that is a candidate for switching / addition, and receives a TA command in the random access response, thereby establishing synchronization with the base station antenna #1 that is a candidate for switching / addition.

[0011] When transmitting uplink signals after switching to base station antenna #1, the user terminal transmits in accordance with the notified TA command, thereby enabling communication at appropriate transmission and reception timing even if the propagation delay changes significantly due to switching of the base station antenna.

[0012] In the method of Patent Document 1, the user terminal can grasp the information of the propagation delay of the base station antenna that is a candidate for switching / addition, but when communicating simultaneously with multiple base station antennas, if the propagation delay between the base station antennas differs significantly, this may cause a large difference in the reception timing at the base station antenna or the user 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] Related technology for switching / adding base station antennas using only channel power gain has the problem that large fluctuations in propagation delay occur during switching / adding, resulting in a decrease in throughput due to misalignment in reception timing.

[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 wireless 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 connected base station antenna, a propagation delay fluctuation estimation unit that estimates information on propagation delay fluctuations for one or more antennas including a connected base station antenna, and an optimal antenna determination unit that selects one or more optimal connection antennas for a wireless terminal based on the channel power gain fluctuation information and the propagation delay 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 base station antenna, and estimates information on propagation delay fluctuations, including propagation delay differences for multiple antennas and / or information on temporal changes and statistical values ​​of propagation delays for one or more antennas.

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

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

[0021] The present disclosure can provide a wireless base station device, a wireless terminal device, a control method, 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] 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 a base station device and a base station antenna 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 base station antenna selection 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 measuring a propagation delay difference using an uplink signal by a base station device according to the present disclosure. FIG. [Figure 11] FIG. 10 is a diagram illustrating an example of an optimal antenna selection method performed by a base station device according to the present disclosure. [Figure 12] FIG. 10 is a diagram illustrating another example of an optimal antenna selection method performed by a base station device according to the present disclosure. [Figure 13] 10 is a diagram illustrating an example of calculation of a channel variation coefficient by a base station device according to the present disclosure. [Figure 14] 10 is a flowchart illustrating a flow of selecting a base station antenna to be connected by a base station device according to the present disclosure. [Figure 15] 10 is a diagram illustrating an example of the configuration of a connection base station antenna selection unit provided in a base station device according to the present disclosure. [Figure 16] 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 17] 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 18] FIG. 10 is a diagram illustrating an example of an optimal antenna selection method using the difference in Doppler frequency by a base station device according to the present disclosure. [Figure 19] 10 is a diagram illustrating an example of the configuration of a connection base station antenna selection unit provided in a base station device according to the present disclosure. [Figure 20] FIG. 10 is a diagram illustrating an example of the configuration of a user terminal according to the present disclosure. [Figure 21] 10 is a diagram illustrating an example of the configuration of a connection base station antenna selection unit provided in a base station device according to the present disclosure. [Figure 22] 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 23] 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 24] FIG. 10 is a diagram illustrating an example of estimation of propagation delay variation per beam by a base station device according to the present disclosure. [Figure 25] 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 26] 10 is a diagram illustrating an example of acquisition of propagation delay information between a user terminal and multiple base station antennas by a base station device according to the present disclosure. FIG. [Figure 27] 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. The wireless communication system according to the present disclosure selects a base station antenna to be used for communication by taking into consideration both "fluctuations in channel gain" and "fluctuations in propagation delay" in a wireless communication system having multiple distributed base station antennas, such as a distributed MIMO (Multiple-Input Multiple-Output) system or an SFN (Single Frequency Network). For example, the wireless communication system according to the present disclosure switches / adds a base station antenna to be used for communication when the fluctuations in channel gain satisfy a predetermined condition (range) that allows switching without causing any problems, and when the fluctuations in propagation delay are smaller than a predetermined value.

[0027] Here, "fluctuation in channel gain" refers to either or both of "the difference between the channel power gain of the currently connected base station antenna and the channel power gain of the base station antenna that is a candidate for switching / addition" and "changes over time in the channel power gain of the currently connected base station antenna."

[0028] Furthermore, "variation in propagation delay" refers to either or both of "the difference between the propagation delay for the currently connected base station antenna and the propagation delay for the base station antenna of the candidate for switching / addition" and "changes over time in the propagation delay for the currently connected base station antenna."

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

[0030] Fig. 6 is a diagram showing an example of the configuration of a base station device and a base station antenna 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 base station antenna devices 2. Hereinafter, the Nth base station antenna device 2 will also be referred to as base station antenna device #N. For example, the first base station antenna device 2 will also be referred to as base station antenna device #1. A base station antenna device will also be referred to as a base station antenna, an antenna device, or simply an antenna.

[0031] The base station 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 base station antenna device 2 may be appropriately interpreted as a distributed antenna, a TRP (Transmission and Reception Point), an access point, an RRH (Remote Radio Head), an RU (Radio Unit), etc.

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

[0035] The digital transceiver 11 performs modulation and demodulation of signals, similar to the digital transceiver 21 of the base station antenna device 2. Part or all of the digital transceiver 11 may be provided in the base station antenna device 2.

[0036] The connecting base station antenna selector 12 selects a base station antenna to be used for communication with a user terminal. Specifically, it estimates the channel gain fluctuations and propagation delay fluctuations between the currently connected base station antenna and user terminal, and between one or more base station antennas and user terminals that are candidates for switching / addition, and determines the optimal connecting base station antenna based on the estimated channel gain fluctuations and propagation delay fluctuations. More specific operation will be described in detail in the following sections.

[0037] The radio resource control unit 13 specifically determines the radio resources (antenna, beam, frequency, time, etc.) to be used for each user terminal based on the connecting base station antenna information determined by the connecting base station antenna selection unit 12. The radio resource control unit 13 may also be called a scheduler unit.

[0038] 7 is a diagram showing an example of the configuration of a connection base station antenna selector provided in a base station device according to the present disclosure. As shown in FIG. 7, the connection base station antenna selector 12 provided in the base station device 1 according to the present disclosure includes a channel gain fluctuation estimator 121, a propagation delay fluctuation estimator 122, and an optimal antenna determiner 123.

[0039] The channel gain fluctuation estimation unit 121 estimates the fluctuation of the channel gain of one or more base station antennas including the currently connected base station antenna. For example, the channel power gain p s and the channel power gain p of the connected base station antenna. m The channel power difference Δ p =p s -p m As another example, the channel power gain p mThe time variation and statistical value of , the channel power gain p of the base station antenna that can be switched / added s It is also possible to calculate the time-dependent changes and statistical values ​​of the above.

[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 user terminal U1.

[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 user terminal U1. In particular, p s It is recommended to use an uplink reference signal when measuring p. Since the uplink reference signal is periodically transmitted for communication with the base station antenna to which the user terminal U1 is currently connected, it is possible to measure the channel of the base station antenna to be switched / added without transmitting an additional reference signal. s It is possible to measure.

[0042] As another example, the channel power gain p s does not necessarily need to be actually measured using a reference signal or the like, but may be estimated using channel gain information of a currently connected base station antenna or a base station antenna that has previously connected. It may also be estimated using past measurement information or a database accumulated by simulation in addition to the channel gain information. It may be estimated statistically based on the information, or may be estimated using learning such as machine learning or deep learning, a database, or the like. The learning method may be determined by general methods such as supervised learning, unsupervised learning, or reinforcement learning.

[0043] The propagation delay variation estimation unit 122 estimates the variation of the propagation delay for one or more base station antennas, including the currently connected base station antenna. For example, the propagation delay τ between the base station antenna to be switched / added and the user terminal is s and the propagation delay τ between the connected base station antenna and the user 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 statistical value of , the propagation delay τ for the base station antenna of the switching / addition candidate s It is also possible to calculate the time-dependent changes and statistical values ​​of the above.

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

[0045] For example, τ m and τ s Without directly measuring Δ τ Specifically, as shown in FIG. 10, the user terminal U1 may calculate the reception time t m , the reception time t at the base station antenna of the candidate for switching / addition s Measure Δ τ =|t s -t m The propagation delay difference may be calculated by |

[0046] Furthermore, when calculating the time variation of the propagation delay for any one base station antenna, τm and τ s Instead of directly measuring the time, the time change may be calculated by calculating the difference or statistical value of the propagation delay for the base station antenna between a plurality of radio slots that differ in time.

[0047] As another example, the propagation delay τ of the base station antenna of the candidate for switching / addition s does not necessarily have to be actually measured directly or indirectly using a reference signal or the like, but may be estimated using propagation delay information of a currently connected base station antenna or a previously connected base station antenna, or the position and movement information of a base station antenna or a user terminal. In addition to the above information, it may be estimated using past measurement information or a database accumulated by simulation. It may be estimated statistically based on the information, or may be estimated using learning such as machine learning or deep learning, a database, or the like. As a learning method, it may be determined by general methods such as supervised learning, unsupervised learning, and reinforcement learning.

[0048] The optimum antenna determination unit 123 selects the optimum connecting base station antenna for the user terminal based on the value of the channel gain fluctuation calculated by the channel gain fluctuation estimation unit 121 and the value of the propagation delay fluctuation calculated by the propagation delay fluctuation estimation unit 122.

[0049] For example, the channel power gain difference Δ between the two base station antennas calculated by the channel gain fluctuation estimation unit 121 is p and the difference Δ between the propagation delays between the two base station antennas calculated by the propagation delay variation estimation unit 122. τ Based on this, the optimum base station antenna for the user terminal to connect to is selected.

[0050] As an example, a threshold Th corresponding to the channel power difference is p and the threshold value Th corresponding to the propagation delay difference τ The method for determining the optimum base station antenna using the channel power difference Δ p is the threshold Th p Larger, propagation delay difference Δ τ is the threshold Thτ The smaller candidate base station antenna for switching / addition may be selected as the optimal antenna.

[0051] FIG. 11 shows an example of selection when there are six candidate base station antennas to switch / add. p,n and Δ τ,n indicates the channel power fluctuation and propagation delay fluctuation between the n-th base station antenna among the six candidate base station antennas to be switched / added and the currently connected base station antenna, respectively.

[0052] In the example of FIG. 11, among the six candidate base station antennas for switching / addition, the one (Δ τ,n , Δ p,n ) can be selected as the optimum antenna. If there is one or more base station antennas located in the optimum antenna area, and if the user terminal can communicate with multiple base station antennas, the one or more base station antennas can be selected as the optimum antennas and added as the connected base station antennas. If the user terminal can communicate with only one base station antenna, one base station antenna can be selected from one or more base station antennas located in the optimum antenna area and switched from the currently connected base station antenna. In this case, for example, among the multiple base station antennas located in the optimum antenna area, the base station antenna with the largest delay difference Δ τ It is possible to select a base station antenna with a smaller channel power difference Δ p A base station antenna with a larger

[0053] In addition, if the number of base station antennas to be used for communication with a user terminal can be determined arbitrarily, the number of base station antennas to be used for communication with a user terminal may be determined based on the number of base station antennas located in the optimal antenna area.

[0054] As another example, the optimum antenna determination unit 123 may use, as an index of channel gain fluctuation, a statistical value Δ p, the optimum antenna may be selected in the same manner as in the example of FIG.

[0055] As an example, the statistical value representing the change in channel power may be a coefficient of variation CV=σ / μ. For example, the coefficient of variation may be calculated by calculating the mean μ and standard deviation σ from the distribution of channel power data within a range of a window size W centered on an arbitrary time, as shown in Figure 13. The example in Figure 13 shows that the value of the coefficient of variation CV is large at times t1 and t3, when the channel is fluctuating significantly over time, and the coefficient of variation is small at time t2, when the channel is fluctuating relatively slowly over time.

[0056] In the example of FIG. p By setting =-CV, it is possible to select a base station antenna whose statistical value of channel gain fluctuation is smaller than the specified value, that is, whose channel fluctuation is gentler, as the optimum antenna.

[0057] Furthermore, the optimum antenna determination unit 123 notifies the radio resource control unit 13 of information about the one or more optimum antennas (for example, base station antenna indexes) that have been determined.

[0058] In the example of the optimum antenna selection method described using Figs. 11 to 13, a threshold Th related to the fluctuation of propagation delay is used as an example of a threshold for determining the optimum antenna area. τ , 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.

[0059] Furthermore, the threshold values ​​for determining these optimal antenna areas, the range of the optimal antenna areas, etc. may be calculated and set in advance based on the installation positions of each base station antenna device 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.

[0060] FIG. 14 shows an example of a flowchart of a method for selecting an antenna for a base station to be connected.

[0061] As described above, the wireless communication system according to the present disclosure can select and switch / add a base station antenna with high channel gain while suppressing changes in propagation delay when switching / adding a base station antenna used for communication while a user terminal is moving. That is, by suppressing the adverse effects of a sudden change in propagation delay when switching a connected base station antenna or a difference in propagation delay when adding a connected base station antenna, deviations in reception timing at the user terminal or base station antenna are reduced, and the adverse effects of propagation delay exceeding the CP length and fluctuations in the channel frequency direction due to the effects of propagation delay are reduced, enabling stable communication.

[0062] The reason for this is that when switching / adding a connected base station antenna, not only information on channel gain fluctuations but also information on propagation delay fluctuations is taken into consideration. When switching the connected base station antenna, the switching is performed at a timing when the fluctuation in propagation delay before and after the switch is small, so communication can be continued with a base station antenna with high channel gain while reducing the difference in reception timing at the user terminal or base station antenna. When adding a connected base station antenna, the difference in propagation delay between the multiple base station antennas with which the user terminal communicates is kept small, reducing the difference in reception timing at the user terminal or base station antenna.

[0063] <Embodiment 2> 15 is a diagram showing an example of the configuration of a connection base station antenna selector provided in a base station device according to the present disclosure. As shown in FIG. 15, the connection base station antenna selector 12a provided in the base station device 1a according to the present disclosure further includes a Doppler frequency fluctuation estimator 124 in addition to a channel gain fluctuation estimator 121, a propagation delay fluctuation estimator 122, and an optimal antenna determiner 123.

[0064] The Doppler frequency fluctuation estimation unit 124 estimates fluctuations in the Doppler frequency (Doppler shift) for one or more base station antennas, including the currently connected base station antenna.

[0065] As an example, the Doppler frequency f s and the Doppler frequency f m The absolute value of the difference Δ f =|f s -f m As another example, the Doppler frequency f m The Doppler frequency f s You can also calculate the time variation and statistical values ​​of f m and f s may be a measurement value using a downlink reference signal reported by the user terminal. m and f s may be calculated using an uplink reference signal transmitted from the user terminal.

[0066] 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 16. Similarly, in the case of calculation 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 16 shows an example where the subcarrier spacing is 120 kHz.

[0067] The Doppler frequency fluctuation estimation unit 124 calculates f m and f s Without directly measuring the phase rotation of an arbitrary uplink signal of the user terminal, Δ is calculated based on the difference in the phase rotation measured using the reference signals of the currently connected base station antenna and the base station antenna of the candidate for switching / addition. f may be calculated.

[0068] Specifically, as shown in FIG. 17, the phase rotation amount f of the uplink signal transmitted by the user terminal U1 during communication with the currently connected base station antenna is m , the phase rotation amount f of the base station antenna to be switched / added s Measure Δ f =|f s -f m The difference in Doppler frequency between the two base station antennas may be calculated from the difference in the amount of phase rotation using |.

[0069] Furthermore, when calculating the time variation of the Doppler frequency for any one base station antenna, f m and f s Instead of directly measuring the phase rotation amount, the change over time may be calculated by calculating the difference or statistical value of the phase rotation amount for the base station antenna between multiple radio slots that differ over time.

[0070] The optimum antenna determination unit 123 calculates the channel gain fluctuation value Δ p and the propagation delay value Δ calculated by the propagation delay variation estimation unit 122. τ In addition, the Doppler frequency fluctuation value Δ f Based on the value of , the optimum connecting base station antenna for the user terminal is selected.

[0071] As an example of the optimum antenna determination method, a threshold Th corresponding to the channel gain fluctuation is used. p and the threshold value Th corresponding to the propagation delay difference τIn addition, the threshold value Th corresponding to the Doppler frequency difference f A method for determining the optimum antenna will be described below. p is the threshold Th p Larger,propagation delay variation Δ τ is the threshold Th τ Smaller,Doppler frequency variation Δ f is the threshold Th f The base station antenna with the smaller number of switch / add candidates may be selected as the optimal antenna.

[0072] FIG. 18 shows an example of selection when there are six candidate base station antennas to switch / add. f,n indicates the Doppler frequency fluctuation between the nth base station antenna among the six candidate base station antennas to be switched / added and the currently connected base station antenna.

[0073] In the example of FIG. 18, among the six candidate base station antennas for switching / addition, only one (Δ f,n , Δ τ,n , Δ p,n The first and fourth base station antennas, where Δ f,n , Δ τ,n , Δ p,n ) is located in the optimum antenna area, if the user terminal can communicate with multiple base station antennas, multiple base station antennas may be selected as the optimum antenna, and if the user terminal can communicate with only one base station antenna, one base station antenna may be selected from the multiple base station antennas located in the optimum antenna area. For example, among the multiple base station antennas, the one with the greatest propagation delay difference Δ τ A base station antenna with a smaller Doppler frequency difference Δ f It is possible to select a base station antenna with a smaller channel power difference Δ p A base station antenna with a larger

[0074] 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.

[0075] <Third Embodiment> 19 is a diagram showing an example of the configuration of a connecting base station antenna selector provided in a base station device according to the present disclosure. As shown in FIG. 19, a connecting base station antenna selector 12b provided in a base station device 1b according to the present disclosure further includes a compensation parameter calculator 125 in addition to a channel gain fluctuation estimator 121, a propagation delay fluctuation estimator 122, and an optimal antenna determiner 123.

[0076] 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 propagation delay based on the determined base station antenna information, channel gain information, and propagation delay information.

[0077] As one example, the compensation parameter in the uplink may be information that determines the transmission timing of the user terminal, such as a TA command, etc. As another example, the compensation parameter in the downlink may be information that determines the reception timing of the user terminal.

[0078] 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 propagation delays of base station antennas #1, #2, and #3 are τ1, τ2, and τ3, respectively, the compensation parameter T τ The calculation method may be, for example, as shown in the following equation (1), where the delay is given by a weighted average of the propagation delays of the respective base station antennas selected by the optimum antenna determination unit 123.

[0079]

number

[0080] The weighting coefficient w nmay 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 T τ may be given by the following equation (2):

[0081]

number

[0082] The calculated compensation parameters are reported to the user terminal, and the user terminal compensates for the propagation delay based on the reported compensation parameters. For example, the compensation parameters may be included in a Transmission Configuration Indication (TCI) state reported from the base station to the user terminal. As another example, the compensation parameters may be reported to the user terminal using Radio Resource Control (RRC) signaling, MAC Media Access Control Element (CE), or Downlink Control Information (DCI).

[0083] When a user terminal simultaneously communicates with base station antennas #1, #2, and #3, if the propagation delay τ1 of base station antenna #1 is only considered and compensated for, the propagation delays 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 user terminal. τ By compensating for the propagation delay based on the above, it is possible to compensate for the different propagation delays of multiple base station antennas on an average basis and reduce reception timing errors. In addition, weighting based on the channel power gain allows prioritizing propagation delay compensation according to the channel gain.

[0084] <Fourth Embodiment> 20 is a diagram illustrating an example of the configuration of a user terminal according to the present disclosure. As shown in FIG. 20, a user terminal U1 includes one or more antenna elements 31, an RF transceiver unit 32, a digital transceiver unit 33, and a control unit 34.

[0085] 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.

[0086] When two or more base station antennas are selected by the optimal antenna determination unit 123 of the base station device 1, the compensation parameter calculation unit 341 determines compensation parameters for the propagation delay based on the determined base station antenna information, channel gain information, and propagation delay information.

[0087] As one example, the compensation parameter in the uplink may be information that determines the transmission timing of the user terminal, such as a TA command, etc. As another example, the compensation parameter in the downlink may be information that determines the reception timing of the user terminal.

[0088] The method for calculating the compensation parameter may be, for example, a weighted average of the propagation delays 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).

[0089] In this embodiment, the connecting base station antenna selector 12 may also have a function of notifying the user terminal U1 of the determined optimum antenna information. For example, the optimum antenna information may be included in the status notified from the base station to the user terminal U1. The TCI status may be included in, for example, the MAC CE or DCI.

[0090] Furthermore, the information on the propagation delay and channel power gain may be reported from the base station antenna or may be measured by the user terminal U1.

[0091] <Fifth Embodiment> 21 is a diagram showing an example of the configuration of a connecting base station antenna selector provided in a base station device according to the present disclosure. As shown in FIG. 21, a connecting base station antenna selector 12c provided in a base station device 1c according to the present disclosure includes a channel gain fluctuation estimator 121 and a propagation delay fluctuation estimator 122, and includes an optimal antenna beam determiner 126 instead of the optimal antenna determiner 123.

[0092] 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.

[0093] As an example, as shown in FIG. 22, when a user 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 23, 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.

[0094] The propagation delay variation estimation unit 122 estimates the variation in propagation delay for each analog beam of one or more base station antennas, including the currently connected base station antenna.

[0095] As an example, as shown in FIG. 24, when a user 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 Propagation delay τ during use s,bs and the analog beam #b of the connected base station antenna #m. m Propagation delay τ m,bm The absolute value of the difference Δ τ =|τ s,bs -τ m,bm However, as in the example described in FIG. 23, if the base station antenna can use multiple analog beam codebooks, s=m, that is, the propagation delay variation may be calculated for different beams of the currently connected base station antenna. As another example, the time variation or statistical value of the propagation delay may be calculated.

[0096] The optimal antenna / beam determination unit 126 selects the optimal connecting base station antenna and analog beam for the user 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 propagation delay fluctuation for each analog beam calculated by the propagation delay fluctuation estimation unit 122.

[0097] 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 in propagation delay between the two beams calculated by the propagation delay variation estimation unit 122, Δ τ As an example, similar to the example described in FIG. 11, a threshold Th corresponding to the channel power difference is used as shown in FIG. 25. p and the threshold value Th corresponding to the propagation delay difference τ may be used to determine the optimal base station antenna and analog beam.

[0098] <Sixth Embodiment> The connecting base station antenna selector provided in the base station device according to the present disclosure has the same configuration as the example shown in Fig. 7. Here, the user terminal in this embodiment may have a function to measure information on propagation delays between the user terminal and multiple base station antennas and report the information to the base station device 1.

[0099] As an example, as shown in Figure 26, the information to be reported may be the delay time actually measured between each of a plurality of base station antennas and the user terminal U1. As another example, the information to be reported may be the difference Δ τ =|t s -t m | is also possible.

[0100] The report to the base station may be made using, for example, a random access response, a CSI (Channel State Information) report, a PUCCH (Physical Uplink Control Channel), a PUSCH (Physical Uplink Shared Channel), or the like.

[0101] According to the present disclosure, it is possible to obtain information about propagation delays between a user terminal and multiple base stations by performing measurements using downlink reference signals transmitted from the base stations.

[0102] (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.

[0103] 27 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. Furthermore, computer 300 may include input devices such as a keyboard and a mouse, and a display device such as a display, as other components not shown.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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 propagation delay variation information estimation process implemented by the user 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 propagation delay 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. 27 is a computer program that implements the propagation delay 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.

[0108] 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.

[0109] 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.

[0110] Furthermore, some or all of the above-described embodiments can be described as, but are not limited to, the following supplementary notes.

[0111] (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 base station antenna; a propagation delay variation estimation unit that estimates information on propagation delay variations for one or more antennas including a currently connected base station 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 propagation delay fluctuation; A wireless base station device comprising:

[0112] (Appendix 2) The propagation delay variation estimation unit calculates, as the information of the propagation delay variation, a propagation delay difference between a propagation delay for a base station antenna of a switching destination / candidate for addition and a propagation delay for a base station antenna currently connected, or / and calculates a time variation or a statistical value of the propagation delay for the base station antenna currently connected and / or the base station antenna of a switching destination / candidate for addition. Appendix 1: Wireless base station equipment.

[0113] (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 base station antenna of a switching destination / candidate to be added and a channel power gain of a currently connected base station antenna, or / and calculates a time variation or a statistical value of the channel power gain of the currently connected base station antenna or / and the switching destination / candidate to be added base station antenna. 3. The wireless base station device according to claim 1 or 2.

[0114] (Appendix 4) the propagation delay variation estimation unit estimates the propagation delay variation information using reception information of uplink signals received from a wireless terminal by a plurality of antenna devices. 4. The wireless base station device according to claim 1.

[0115] (Appendix 5) the propagation delay variation estimation unit uses information on a difference in propagation delay for a plurality of antenna devices reported from a wireless terminal to a base station device as the information on the propagation delay variation. 4. The wireless base station device according to claim 1.

[0116] (Appendix 6) The information on the propagation delay 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. 6. The wireless base station device according to claim 5.

[0117] (Appendix 7) the propagation delay variation estimation unit estimates the propagation delay variation information by learning or by using a database, using wireless terminal information and channel power gain information of the wireless terminal previously acquired by the base station device. 4. The wireless base station device according to claim 1.

[0118] (Appendix 8) 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 propagation delay fluctuation, and selects one or more antennas included in the optimum antenna area as optimum connection antennas for the wireless terminal. 8. The wireless base station device according to claim 1.

[0119] (Appendix 9) 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 propagation delay fluctuation, and selects one or more base station antennas included in the optimum antenna area as optimum base station antennas to connect to the wireless terminal. 9. The wireless base station device according to any one of Supplementary notes 1 to 8.

[0120] (Appendix 10) the optimum antenna determination unit selects one or more optimum connection base station antennas using information on a propagation delay difference between a propagation delay for a base station antenna to be switched to / added and a propagation delay for a currently connected base station antenna as the information on the propagation delay variation. 10. The wireless base station device according to any one of Supplementary notes 1 to 9.

[0121] (Appendix 11) The optimum antenna determination unit selects one or more optimum connection base station antennas using, as the information on the propagation delay fluctuation, temporal changes or statistics of propagation delay for the currently connected base station antenna and / or the base station antenna of a candidate for switching / addition. 11. The wireless base station device according to claim 1.

[0122] (Appendix 12) 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 base station antenna to be switched to / candidate for addition and a channel power gain of an antenna currently connected, or / and time-varying or statistical values ​​of the channel power gain of the antenna currently connected and / or the antenna to be switched to / candidate for addition. 12. The wireless base station device according to claim 1.

[0123] (Appendix 13) The system further includes a Doppler frequency fluctuation estimation unit that estimates information on Doppler frequency fluctuations for one or more antennas including the currently connected antenna, and the optimal antenna determination unit selects the optimal connected antenna using the information on the Doppler frequency fluctuations. 13. The wireless base station device according to claim 1.

[0124] (Appendix 14) The Doppler frequency fluctuation estimation unit calculates, as the information of the Doppler frequency fluctuation, a Doppler frequency difference between a Doppler frequency between a base station antenna of a switching destination / candidate for addition and a wireless terminal and a Doppler frequency between a base station antenna currently connected and a wireless terminal, or / and calculates a time variation or a statistical value of the Doppler frequency between the base station antenna currently connected and / or the base station antenna of a switching destination / candidate for addition and a wireless terminal. 14. The wireless base station device according to claim 13.

[0125] (Appendix 15) 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 propagation delay fluctuation, and a range of values ​​of the Doppler frequency fluctuation, and selects one or more base station antennas included in the optimum antenna area as optimum connection antennas for the wireless terminal. 15. The wireless base station device according to claim 13 or 14.

[0126] (Appendix 16) a correction parameter calculation unit that determines a propagation delay correction value based on the optimum antenna information determined by the optimum antenna determination unit and information on propagation delays for one or more of the base station antennas; The propagation delay correction value determined by the correction parameter calculation unit is reported to the wireless terminal. 16. The wireless base station device according to any one of Supplementary notes 1 to 15.

[0127] (Appendix 17) the propagation delay correction value is a weighted average of the propagation delays of the one or more base station antennas; 17. The radio base station apparatus according to claim 16.

[0128] (Appendix 18) the weighted average of the propagation delays is weighted by weighting factors calculated using channel power gains of the one or more base station antennas; 18. The wireless base station device according to claim 17.

[0129] (Appendix 19) the radio base station device uses one or more beams for each antenna, and the channel gain fluctuation estimator, the propagation delay fluctuation estimator, and the optimum antenna determiner operate taking into account the one or more beams. 19. The wireless base station device according to any one of Supplementary notes 1 to 18.

[0130] (Appendix 20) 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.

[0131] (Appendix 21) The downlink reference signal is received from one or more base station antennas including the currently connected base station antenna, and information on propagation delay fluctuations including a propagation delay difference for a plurality of antennas and / or information on time changes and statistical values ​​of the propagation delay for one or more antennas is estimated. Wireless terminal device.

[0132] (Appendix 22) and reporting the information on the propagation delay variation to a base station device. Appendix 21: Wireless terminal equipment.

[0133] (Appendix 23) determining a propagation delay correction value using propagation delays 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 propagation delay based on the propagation delay correction value; 23. The wireless terminal device according to claim 21 or 22.

[0134] (Appendix 24) the propagation delay correction value is a weighted average of the propagation delays of the one or more base station antennas; 24. The wireless terminal device of claim 23.

[0135] (Appendix 25) the weighted average of the propagation delays is weighted by weighting factors calculated using channel power gains of the one or more base station antennas; 25. The wireless terminal device of claim 24.

[0136] (Appendix 26) A wireless base station device Estimating channel power gain fluctuation information for one or more antennas including a serving base station antenna; Estimating propagation delay variation information for one or more antennas, including the currently serving base station antenna; selecting one or more optimal connection antennas for the wireless terminal based on the information about the channel power gain variation and the information about the propagation delay variation; Control method.

[0137] (Appendix 27) estimating channel power gain fluctuation information of one or more antennas including the currently serving base station antenna; estimating propagation delay variation information for one or more antennas, including a serving base station antenna; selecting one or more optimal connection antennas for a wireless terminal based on the channel power gain variation information and the propagation delay variation information; A control program that causes a computer to execute the above.

[0138] (Appendix 28) The wireless terminal device receiving a downlink reference signal from one or more base station antennas including a currently connected base station antenna; Estimating propagation delay variations, including differences in propagation delays for multiple antennas and / or information about the time evolution and statistics of the propagation delays for one or more antennas; Control method.

[0139] (Appendix 29) receiving a downlink reference signal from one or more base station antennas including a currently connected base station antenna; estimating propagation delay variation information, including propagation delay differences for multiple antennas and / or propagation delay variation information for one or more antennas, including time-varying and statistical information; A control program that causes a computer to execute the above.

[0140] Some or all of the elements (e.g., configurations and functions) described in Supplementary Notes 2 to 20 that are dependent on Supplementary Notes 1 may also be dependent on Supplements 26 and 27 in the same dependency relationship as Supplementary Notes 2 to 20. Also, some or all of the elements (e.g., configurations and functions) described in Supplementary Notes 22 to 25 that are dependent on Supplementary Notes 21 may also be dependent on Supplements 28 and 29 in the same dependency relationship as Supplementary Notes 22 to 25. 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]

[0141] 1 Base station equipment (wireless base station equipment) 2 Base station antenna equipment 11 Digital transmitter / receiver 12. Connection base station antenna selection unit 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 Propagation delay variation estimation unit 123 Optimal Antenna Determination Unit 124 Doppler frequency fluctuation 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 User 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 base station antenna; a propagation delay variation estimation unit that estimates information on propagation delay variations for one or more antennas including a currently connected base station antenna; an optimal antenna determination unit that selects one or more optimal connection antennas for a wireless terminal based on the information on the channel power gain fluctuation and the information on the propagation delay fluctuation; A wireless base station device comprising:

2. The propagation delay variation estimation unit calculates, as the information of the propagation delay variation, a propagation delay difference between a propagation delay for a base station antenna of a switching destination / candidate for addition and a propagation delay for a base station antenna currently connected, or / and calculates a time variation or a statistical value of the propagation delay for the base station antenna currently connected and / or the base station antenna of a switching destination / candidate for addition.

2. A wireless 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 base station antenna of a switching destination / candidate to be added and a channel power gain of a currently connected base station antenna, or / and calculates time-varying changes or statistical values ​​of the channel power gain of the currently connected base station antenna and / or the switching destination / candidate to be added base station antenna. The radio base station device according to claim 1 .

4. the propagation delay variation estimation unit estimates the propagation delay variation information using reception information of uplink signals received from a wireless terminal by a plurality of antenna devices. The radio base station device according to claim 1 .

5. the propagation delay variation estimation unit uses information on a difference in propagation delay for a plurality of antenna devices reported from a wireless terminal to a base station device as the information on the propagation delay variation. The radio base station device according to claim 1 .

6. The information on the propagation delay 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 5 .

7. the propagation delay variation estimation unit estimates the propagation delay variation information by learning or by using 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 .

8. 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 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 1 .

9. 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 propagation delay fluctuation, and selects one or more base station antennas included in the optimum antenna area as optimum base station antennas to connect to the wireless terminal. The radio base station device according to claim 1 .

10. the optimum antenna determination unit selects one or more optimum connection base station antennas using information on a propagation delay difference between a propagation delay for a base station antenna to be switched to / added and a propagation delay for a currently connected base station antenna as the information on the propagation delay variation. The radio base station device according to claim 1 .

11. The optimum antenna determination unit selects one or more optimum connection base station antennas using, as the information on the propagation delay fluctuation, temporal changes or statistics of propagation delay for the currently connected base station antenna and / or the base station antenna of a candidate for switching / addition. 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 channel power gain fluctuation, information on a channel power difference between a channel power gain of a base station antenna to be switched to / candidate for addition and a channel power gain of an antenna currently connected, and / or time-varying or statistical values ​​of the channel power gain of the antenna currently connected and / or the antenna to be switched to / candidate for addition. The radio base station device according to claim 1 .

13. The system further includes a Doppler frequency fluctuation estimation unit that estimates information on Doppler frequency fluctuations for one or more antennas including a currently connected antenna, and the optimal antenna determination unit selects the optimal connected antenna using the information on the Doppler frequency fluctuations. The radio base station device according to claim 1 .

14. The Doppler frequency fluctuation estimation unit calculates, as the information of the Doppler frequency fluctuation, a Doppler frequency difference between the Doppler frequency between the base station antenna of the switching destination / addition candidate and the wireless terminal and the Doppler frequency between the base station antenna currently connected and the wireless terminal, or / and calculates temporal changes and statistical values ​​of the Doppler frequency between the base station antenna currently connected and / or the base station antenna of the switching destination / addition candidate and the wireless terminal. The radio base station device according to claim 13.

15. 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 propagation delay fluctuation, and a range of values ​​of the Doppler frequency fluctuation, and selects one or more base station antennas included in the optimum antenna area as optimum connection antennas for the wireless terminal. The radio base station device according to claim 13.

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

17. the propagation delay correction value is a weighted average of the propagation delays of the one or more base station antennas. The radio base station device according to claim 16.

18. the weighted average of the propagation delays 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 17.

19. the radio base station device uses one or more beams for each antenna, and the channel gain fluctuation estimator, the propagation delay 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 .

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

21. The downlink reference signal is received from one or more base station antennas including the currently connected base station antenna, and information on propagation delay fluctuations including a propagation delay difference for a plurality of antennas and / or information on a time change or statistical value of the propagation delay for one or more antennas is estimated. Wireless terminal device.

22. and reporting the information on the propagation delay variation to a base station device. A wireless terminal device according to claim 21.

23. determining a propagation delay correction value using propagation delays 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 propagation delay based on the propagation delay correction value; 22. The wireless terminal device of claim 21.

24. the propagation delay correction value is a weighted average of the propagation delays of the one or more base station antennas.

24. The wireless terminal device of claim 23.

25. the weighted average of the propagation delays is weighted by weighting factors calculated using channel power gains of the one or more base station antennas; 25. The wireless terminal device of claim 24.

26. A wireless base station device estimating channel power gain fluctuation information for one or more antennas including a serving base station antenna; Estimating propagation delay variation information for one or more antennas, including the serving base station antenna; selecting one or more optimal connection antennas for the wireless terminal based on the channel power gain variation information and the propagation delay variation information; Control method.

27. estimating channel power gain variation information for one or more antennas including a serving base station antenna; estimating propagation delay variation information for one or more antennas, including a serving base station antenna; selecting one or more optimal connection antennas for a wireless terminal based on the channel power gain variation information and the propagation delay variation information; A control program that causes a computer to execute the above.

Images