JP2018148335A - Radio base station, radio communications system, and control method and control program of radio base station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the load of a baseband processing unit related to the Doppler shift correction at low cost.SOLUTION: A radio base station includes moving speed calculating means that generates moving speed information representing a moving speed and a direction of a certain terminal from among a plurality of wireless terminals with respect to a base station side antenna, and when a certain terminal exists in a certain cell, base station side wireless communication means calculates a downlink transition frequency obtained by subtracting the downlink reference frequency of the downlink signal from the frequency of the downlink signal in which the downlink reference frequency has changed due to the Doppler shift accompanying movement of the terminal with respect to the base station side antenna and an uplink transition frequency obtained by subtracting the uplink reference frequency of the uplink signal from the frequency of the uplink signal in which the uplink reference frequency has changed by the Doppler shift, based on the moving speed information to all terminals existing in the certain cell from among the plurality of wireless terminals, and corrects the frequency change due to the Doppler shift based on the calculated downlink shift frequency and uplink shift frequency.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for correcting a Doppler shift caused by movement of a wireless mobile station in a wireless communication system.

  Due to the development of wireless communication technology such as LTE, a wireless terminal (wireless mobile station) can communicate with a wireless base station even during high-speed movement by a high-speed moving body such as a bullet train.

  However, in a radio terminal moving at high speed, the frequency of uplink and downlink radio signals change (Doppler shift) due to the Doppler effect, so that the communication performance deteriorates.

  An example of a technique for correcting the Doppler shift is disclosed in Patent Document 1. The mobile communication system of Patent Literature 1 includes a base station device (wireless base station) and a mobile station device (wireless terminal). The base station apparatus includes a phase error detection unit and a phase error rotation unit. The phase error detection unit detects a phase error caused by the Doppler shift in the received wave from each mobile station device. Based on the phase error detected by the phase error detection unit, the phase error rotation unit transmits a transmission symbol in the baseband region so that the Doppler shift generated in the downlink from the base station device to each mobile station device is canceled. Rotate the phase. As a result of the above configuration, in the mobile communication system of Patent Document 1, the base station apparatus controls the frequency of the transmission signal from the base station apparatus so that the Doppler shift for each mobile station apparatus is canceled.

  In the mobile communication system of Patent Document 1, the base station apparatus performs Doppler shift correction for each mobile station apparatus using a baseband processing unit. However, when the amount of Doppler shift increases, the load on the Doppler shift correction in the baseband processing unit increases. As the number of wireless terminals moving at high speed increases, the number of terminals that support Doppler shift correction in the baseband processing unit also increases, and accordingly, the load on Doppler shift correction in the baseband processing unit increases. . That is, in the mobile communication system of Patent Document 1, when the number of mobile station devices moving at high speed increases, Doppler shift correction in the baseband processing unit of the base station device due to Doppler shift correction in the base station device is performed. There is a problem that this load increases.

  When a large number of wireless terminals exist inside a mobile body that moves at high speed, such as a Shinkansen, the load caused by Doppler shift correction in the wireless base station is particularly large.

  The wireless communication system of Patent Literature 2 includes a wireless base station, a user terminal (wireless terminal), and a joint reception device, and the wireless base station follows the movement of the user terminal using beamforming. The user terminal and the joint reception device exist inside the mobile body. The user terminal transfers the signal received from the radio base station to the joint reception device. Then, the joint reception apparatus performs signal detection processing on the signal transferred from the user terminal, and returns the result of the signal detection processing to the user terminal. The user terminal acquires data by demodulating the result of the signal detection process returned from the joint reception device. As a result of the above configuration, the wireless communication system of Patent Document 2 suppresses inter-terminal interference caused by an increase in the number of moving user terminals and suppresses a decrease in communication performance.

  An example of the beam forming technique is disclosed in Patent Document 3. In Patent Document 3, beam forming is realized using a phased array antenna.

JP 2007-81952 A Japanese Patent Laying-Open No. 2015-126473 JP-A-11-186829

  However, in the wireless communication system of Patent Document 2, it is necessary to install a joint receiving device for each mobile body, and since the signal is exchanged and optimized between the joint receiving device and the user terminal, the processing becomes complicated. As the load increases, the configuration is not cheap.

  The present invention has been made in view of the above-described problems, and a main object of the present invention is to inexpensively suppress the load on the baseband processing unit related to the Doppler shift correction generated between the mobile terminal and the mobile terminal that moves at high speed. And

  In one aspect of the present invention, a radio base station receives a downlink signal at a terminal-side reception frequency and transmits an uplink signal at a terminal-side transmission frequency via the terminal-side antenna and the terminal-side antenna. The terminal-side antenna is stationary with respect to the base-station-side antenna via a plurality of wireless terminals that can be moved by a certain high-speed moving body, the base-station-side antenna, and the base-station-side antenna A base station that transmits a downlink signal at a base station side transmission frequency equal to the terminal side reception frequency when the terminal side antenna is stationary with respect to the base station side antenna. A radio base station having a certain cell including a part of a moving path of a certain high-speed moving body. A mobile base station included in the wire communication system, further comprising a moving speed calculation means for generating moving speed information representing a moving speed and direction of a certain terminal among the plurality of wireless terminals at the present time with respect to the base station side antenna. The base station side wireless communication means uniformly applies to all terminals existing in a certain cell among a plurality of wireless terminals based on the movement speed information when a certain terminal exists in a certain cell. A downlink shift frequency obtained by subtracting a downlink reference frequency of a downlink signal from a downlink signal frequency whose downlink reference frequency has changed due to Doppler shift accompanying movement of a certain terminal with respect to the base station side antenna, and an uplink reference frequency of the uplink signal, Calculate the upstream shift frequency subtracted from the upstream signal frequency whose upstream reference frequency has changed due to the shift, and calculate the downstream downstream frequency and the upstream And a Doppler shift correction means for correcting the variation of the frequency due to the Doppler shift on the basis of the transition frequency.

  In one embodiment of the present invention, a wireless communication system receives a downlink signal at a terminal-side reception frequency and transmits an uplink signal at a terminal-side transmission frequency via the terminal-side antenna and the terminal-side antenna. The terminal-side antenna is stationary with respect to the base-station-side antenna via a plurality of wireless terminals that can be moved by a certain high-speed moving body, the base-station-side antenna, and the base-station-side antenna A base station that transmits a downlink signal at a base station side transmission frequency equal to the terminal side reception frequency when the terminal side antenna is stationary with respect to the base station side antenna. A base station side wireless communication means for receiving an uplink signal at a side reception frequency, and a radio base station having a certain cell including a part of a moving path of a certain high-speed moving body In the wireless communication system, the wireless base station further includes a moving speed calculation unit that generates moving speed information indicating a moving speed and a direction of a terminal of the plurality of wireless terminals with respect to the base station side antenna at the present time. The base station side wireless communication means uniformly applies to all terminals existing in a certain cell among a plurality of wireless terminals based on the movement speed information when a certain terminal exists in a certain cell. A downlink shift frequency obtained by subtracting a downlink reference frequency of a downlink signal from a downlink signal frequency whose downlink reference frequency has changed due to Doppler shift accompanying movement of a certain terminal with respect to the base station side antenna, and an uplink reference frequency of the uplink signal, Calculate the upstream shift frequency subtracted from the upstream signal frequency whose upstream reference frequency has changed due to the shift, and calculate the downstream downstream frequency and the upstream And a Doppler shift correction for correcting the variation of the frequency due to the Doppler shift on the basis of the transition frequency.

  In one aspect of the present invention, a control method includes: a terminal-side antenna; and a terminal-side wireless communication unit that receives a downlink signal at a terminal-side reception frequency and transmits an uplink signal at a terminal-side transmission frequency via the terminal-side antenna A plurality of wireless terminals that are likely to be moved by a high-speed moving body, a base station antenna, and a base station antenna, the terminal antenna is stationary with respect to the base station antenna. The base station side transmits the downlink signal at the base station side transmission frequency, which is equal to the terminal side reception frequency, and is equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna. A wireless base station having a certain cell including a part of a moving path of a certain high-speed moving body. A wireless base station control method included in a communication system, comprising: a wireless base station that obtains moving speed information representing a moving speed and direction of a certain terminal among a plurality of wireless terminals at a current time relative to a base station side antenna; Generated by the base station side wireless communication means, when a certain terminal exists in a certain cell, based on the moving speed information, uniformly for all terminals present in the certain cell among the plurality of wireless terminals. In addition, the downlink reference frequency of the downlink signal, the downlink shift frequency obtained by subtracting the downlink reference frequency from which the downlink reference frequency has changed due to the Doppler shift accompanying the movement of a certain terminal with respect to the base station side antenna, and the uplink reference frequency of the uplink signal, Calculate the upshift frequency subtracted from the frequency of the upstream signal whose upstream reference frequency has changed due to Doppler shift. To correct for changes in frequency due to the Doppler shift based on the uplink transition frequency.

  In one aspect of the present invention, a radio base station control program or a recording medium storing such a control program receives a downlink signal at a terminal-side reception frequency via a terminal-side antenna and a terminal-side antenna, Terminal-side radio communication means for transmitting an uplink signal at a terminal-side transmission frequency, via a plurality of radio terminals that have the possibility of being moved by a certain high-speed moving body, a base station-side antenna, and a base station-side antenna When the terminal side antenna is stationary with respect to the base station side antenna, the downlink signal is transmitted at the base station side transmission frequency equal to the terminal side reception frequency, and the terminal side antenna is stationary with respect to the base station side antenna. The base station side radio communication means for receiving the uplink signal at the base station side reception frequency, which is equal to the terminal side transmission frequency. A base station of a terminal of a plurality of wireless terminals at the present time is included in a computer included in a wireless base station included in a wireless communication system including a wireless base station having a certain cell including a part of the moving path When a certain terminal exists in a certain cell by the moving speed calculation processing for generating moving speed information representing the moving speed and direction with respect to the side antenna and the base station side wireless communication means, a plurality of Downlink signal in which the downlink reference frequency of the downlink signal is uniformly changed for all terminals existing in a cell among the radio terminals, and the downlink reference frequency is changed by Doppler shift accompanying the movement of the certain terminal with respect to the base station side antenna. Upstream signal whose upstream reference frequency has been changed by Doppler shift of the downstream transition frequency subtracted from the above frequency and the upstream reference frequency of upstream signal Calculating an uplink transition frequency obtained by subtracting the frequency, based on the calculated downlink transition frequency and the uplink shift frequency to perform a Doppler shift correction process for correcting the variation of the frequency due to the Doppler shift.

  Advantageous Effects of Invention According to the present invention, there is an effect that the load on the baseband processing unit related to Doppler shift correction that occurs with a terminal inside a moving body that moves at high speed can be suppressed at low cost.

It is a block diagram which shows an example of a structure of the radio | wireless communications system in the 1st Embodiment of this invention. 3 is a flowchart illustrating an operation of the wireless communication system according to the first embodiment of the present invention. 4 is a flowchart illustrating an example of an operation of the wireless communication system according to the first embodiment of the present invention. It is a block diagram which shows an example of a structure of the radio | wireless communications system in the 2nd Embodiment of this invention. It is a block diagram which shows an example of a structure of the radio | wireless terminal in the 2nd Embodiment of this invention. It is a block diagram which shows an example of a structure of the wireless base station in the 2nd Embodiment of this invention. It is a figure explaining generation | occurrence | production of the Doppler shift in the 2nd Embodiment of this invention. It is a flowchart which shows operation | movement of the radio | wireless communications system in the 2nd Embodiment of this invention. It is a block diagram which shows an example of the hardware constitutions which can implement | achieve the radio base station in each embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings, equivalent components are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
(First embodiment)
A configuration in the present embodiment will be described.

  FIG. 1 is a block diagram showing an example of a configuration of a wireless communication system according to the first embodiment of the present invention.

  The wireless communication system 805 in this embodiment includes a plurality of wireless terminals 305, 306,... And a wireless base station 405.

  Each of the wireless terminals 305, 306,... Has a possibility of being moved by the high-speed moving body 501. Each of the wireless terminals 305, 306,... Includes an antenna 250 and a wireless communication unit 259.

The wireless communication unit 259 receives a downlink signal at the terminal-side reception frequency F _dr via the antenna 250 and transmits an uplink signal at the terminal-side transmission frequency F _us .

  The radio base station 405 includes a cell 605 including a part of the moving path 811 of the high-speed moving body 501. Radio base station 405 includes an antenna 150, a radio communication unit 159, and a moving speed calculation unit 160.

The radio communication unit 159 transmits a downlink signal at the base station side transmission frequency F _ds via the antenna 150 and receives an uplink signal at the base station side reception frequency F _ur . Here, the terminal side reception frequency F _dr is equal to the base station side transmission frequency F _ds when the antenna 250 is stationary with respect to the antenna 150. The terminal-side transmission frequency F _us is equal to the base station-side reception frequency F _ur when the antenna 250 is stationary with respect to the antenna 150. The wireless communication unit 159 includes a Doppler shift correction unit 158.

  The moving speed calculation unit 160 generates moving speed information of the wireless terminal 305 among the plurality of wireless terminals 305, 306,. The moving speed information represents the moving speed and direction of the wireless terminal 305 with respect to the antenna 150. Hereinafter, a case where the movement speed calculation unit 160 generates movement speed information of the wireless terminal 305 will be described as an example. However, the movement speed calculation unit 160 may move any one of the plurality of wireless terminals 305, 306,. What is necessary is just to produce | generate speed information. Alternatively, the movement speed calculation unit 160 may generate movement speed information regarding the average values of the movement speeds and directions of the plurality of wireless terminals 305, 306,.

  For example, the movement speed calculation unit 160 generates movement speed information based on a plurality of sets of information on a position where the wireless terminal 305 exists and information on a time when the wireless terminal 305 exists at the position. Or the movement speed calculation part 160 produces | generates movement speed information based on the operation information of the high-speed moving body 501, for example.

  When the wireless terminal 305 exists in the cell 605, the Doppler shift correction unit 158 applies Doppler to all the wireless terminals existing in the cell 605 among the plurality of wireless terminals based on the moving speed information. Corrects changes in frequency due to shift. Here, the Doppler shift correction unit 158 does not correct the change in frequency due to the Doppler shift for each wireless terminal existing in the cell 605, but uniformly applies the Doppler shift to all the wireless terminals present in the cell 605. Corrects the frequency change caused by.

  The operation in this embodiment will be described.

  FIG. 2 is a flowchart showing the operation of the wireless communication system in the first embodiment of the present invention. Note that the flowchart shown in FIG. 2 and the following description are examples, and the processing order may be changed, the processing may be returned, or the processing may be repeated depending on the processing that is appropriately obtained.

  First, the moving speed calculation unit 160 generates moving speed information of the wireless terminal 305 at the current time (step S105).

Next, the Doppler shift correction unit 158 calculates the downlink shift frequency _{f d} and the uplink transition frequency _{f u} (step S115). Specifically, the Doppler shift correction unit 158, a downlink reference frequency F _d0, down shift frequency downlink reference frequency F _d0 by Doppler shift caused by the movement relative to the antenna 150 is subtracted from the frequency of the downlink signal which is changed in the wireless terminal 305 _fd is calculated. Also, the Doppler shift correction unit 158, an uplink reference frequency F _u0, calculates the uplink shift frequency f _u subtracted from the frequency of the uplink signal uplink reference frequency F _u0 changes due to the Doppler shift.

Then, the Doppler shift correction unit 158, based on the calculated downlink shift frequency f _d and the uplink transition frequency f _u, corrects the change in frequency due to the Doppler shift (step S125).

  FIG. 3 is a flowchart showing an example of the operation of the wireless communication system according to the first embodiment of the present invention. More specifically, FIG. 3A shows an example of step S125 of FIG. 2, and FIG. 3B shows another example of step S125 of FIG. Note that the flowchart shown in FIG. 3 and the following description are examples, and the processing order may be changed, the processing may be returned, or the processing may be repeated depending on the processing that is appropriately obtained.

  An example of the operation of the wireless communication system 805 will be described with reference to FIG.

Here, the wireless communication unit 259, and determining a terminal-side transmission frequency _{F us} by subtracting a predetermined frequency difference _(F d0 _{-F u0)} from the terminal side reception frequency _{F dr.}

First, the Doppler shift correction unit 158, a downlink reference frequency _{F d0} from the down shift frequency _{f d} and the uplink transition frequency _f base station side transmission frequency by subtracting the sum of the _{u F ds (= F d0 -} (f d + f _u )) and a downlink signal is transmitted at the determined frequency (step S126).

Next, the wireless communication unit 259 receives a downlink signal at the terminal-side reception frequency F _dr (= F _d0 −f _d ) (step S136).

Subsequently, the wireless communication unit 259 subtracts a predetermined frequency difference (F _d0 −F _u0 ) from the terminal side reception frequency F _dr (= F _d0 −f _u ) to thereby determine the terminal side transmission frequency F _us (= F _u0). -f _u) determines the (AFC (Automatic frequency Control) function), it transmits an uplink signal in the determined frequency (step S146).

Subsequently, the wireless communication unit 159 receives an uplink signal at the base station side reception frequency F _ur (= F _u0 ) (step S156).

  With reference to FIG. 3B, another example of the operation of the wireless communication system 805 will be described.

First, the Doppler shift correction unit 158 determines the base station-side transmission frequency F _ds (= F _d0 −f _d ) by subtracting the downlink shift frequency f _d from the downlink reference frequency F _d0 , and the downlink signal at the determined frequency Is transmitted (step S127).

Next, the wireless communication unit 259 receives a downlink signal at the terminal-side reception frequency F _dr (= F _d0 ) (step S137).

Subsequently, the radio communication unit 259 determines the uplink reference frequency F _u0 as the terminal-side transmission frequency F _us (= F _u0 ), and transmits an uplink signal at the determined frequency (step S147).

Subsequently, the wireless communication unit 159 receives an uplink signal at the base station side reception frequency F _ur (= F _u0 + f _u ) (step S157).

Then, the Doppler shift correction unit 158, an uplink signal received, a signal uplink reference frequency _{F u0} changes by up shift frequency _{f u} (the frequency _F u0 + _{f u)} is corrected as (step S167).

The downlink shift frequency f _d and the uplink shift frequency f _u can be calculated by Equation 1 and Equation 2, respectively. However, the speed v is the moving speed of the wireless terminal 305 with respect to the antenna 150, the speed c is the speed of light, and the angle θ is the moving direction of the wireless terminal 305 with respect to the antenna 150. Further, it is assumed that the angle is 0 degree when the wireless terminal 305 approaches the antenna 150 straight, and 180 degrees when the wireless terminal 305 moves straight away from the antenna 150.

  As described above, in the wireless communication system 805 of this embodiment, the wireless base station 405 includes the moving speed calculation unit 160 and the Doppler shift correction unit 158. Then, the moving speed calculation unit 160 generates moving speed information of the wireless terminal 305 at the current time. And the Doppler shift correction | amendment part 158 is the frequency of the frequency by Doppler shift with respect to all the radio | wireless terminals which exist in the cell 605 among several radio | wireless terminals 305,306, ... based on movement speed information. Compensate for changes. Here, the Doppler shift correction unit 158 does not correct the change in frequency due to the Doppler shift for each wireless terminal existing in the cell 605, but uniformly applies the Doppler shift to all the wireless terminals present in the cell 605. Corrects the frequency change caused by. In addition, the wireless communication system 805 includes no special devices other than the wireless terminals 305, 306,... And the wireless base station 405. Therefore, the wireless communication system 805 of the present embodiment has an effect that the load on the baseband processing unit related to the Doppler shift correction generated between the mobile terminal moving at high speed can be suppressed at a low cost.

  Note that the wireless communication unit 159 detects a portion of the frequency change caused by the Doppler shift that cannot be corrected uniformly by the Doppler shift correction unit 158 in the cell 605 of the plurality of wireless terminals 305, 306,. You may correct | amend individually with respect to each terminal which exists. In general, correction for each radio terminal with respect to the Doppler shift is performed in the baseband unit of the radio base station. Further, the smaller the frequency change due to the Doppler shift, the smaller the processing load caused by the correction for the Doppler shift. Therefore, in this case, the radio communication system 805 of the present embodiment has an effect that it is possible to suppress the load on the radio base station due to the correction for each terminal with respect to the Doppler shift in the baseband unit of the radio base station. A technique for correcting a frequency change due to Doppler shift for each terminal is disclosed in, for example, Patent Document 1, and will not be described in detail here.

  Further, in the above description, the Doppler shift correction unit 158 performs Doppler shift on all wireless terminals existing in the cell 605 based on the moving speed information of one wireless terminal 305 existing in the cell 605. The frequency change due to was corrected. However, the Doppler shift correction unit 158 changes the frequency due to the Doppler shift for all the radio terminals existing in the cell 605 based on the average value of the moving speeds of the plurality of radio terminals 305 existing in the cell 605. May be corrected.

  In addition, the cell 605 may be set such that all terminals existing in the cell 605 among the plurality of wireless terminals 305, 306,... Are moved by the high-speed moving body 501. For example, when there is only a terminal that can be moved by the high-speed moving body 501 in the moving path 811, the cell 605 moves by installing the antenna 150 having strong directivity in the downward direction above the moving path 811. It is limited within the range of the path 811. In this case, in the wireless communication system 805 of this embodiment, frequency correction by Doppler shift is performed on a terminal that is not moved by the high-speed moving body 501 with respect to a terminal that is moved by the high-speed moving body 501. There is an effect that it is not applied by mistake.

  Further, in the cell 605, while each of the plurality of wireless terminals 305, 306,... Passes through the cell 605, the direction of each of the wireless terminals 305, 306,. It may be set to be. For example, the antenna 150 having strong directivity in one direction is installed at a low position above the movement path 811 and sufficiently in front of or behind the cell 605 in the movement direction of the high-speed moving body 501. Thus, the direction in which the antenna 150 is desired from each position in the cell 605 is approximately constant. In this case, the wireless communication system 805 of this embodiment has an effect that it is not necessary to calculate the direction of the wireless terminal 305 with respect to the antenna 150.

  When the absolute value of the difference between the uplink reference frequency and the downlink reference frequency is sufficiently smaller than the uplink reference frequency and the downlink reference frequency, the Doppler shift correction unit 158 approximates the downlink shift frequency or the uplink shift frequency. May be calculated automatically. For example, the Doppler shift correction unit 158 calculates one of the downlink shift frequency and the uplink shift frequency, and calculates the sum of the downlink shift frequency and the uplink shift frequency by doubling the calculated one. Also good. In this case, the wireless communication system 805 according to the present embodiment has an effect that the amount of calculation is small as compared with the case where both the downlink shift frequency and the uplink shift frequency are calculated.

The radio base station 405 may further include a beam forming unit (not shown) that causes the position of the cell 605 to follow the movement of the radio terminal 305. In this case, the wireless communication system 805 of this embodiment can easily correct the Doppler shift even when a plurality of high-speed moving bodies having different moving speeds or different moving directions may approach each other. There is an effect. The beam forming technique is disclosed in, for example, Patent Document 3 and will not be described in detail here.
(Second Embodiment)
Next, a second embodiment of the present invention based on the first embodiment of the present invention will be described. In the radio communication system according to the present embodiment, the radio base station adjusts the frequency of a reference clock signal used for modulation of an RF (Radio Frequency) signal based on the frequency shift caused by the Doppler shift.

  A configuration in the present embodiment will be described.

  FIG. 4 is a block diagram illustrating an example of a configuration of a wireless communication system according to the second embodiment of the present invention. In FIG. 4, two high-speed moving bodies, a high-speed moving body 501 and a high-speed moving body 502, move in the moving path 811. In FIG. 4, the movement path 811 is divided into five positions of a position 701, a position 702, a position 703, a position 704, and a position 705. In FIG. 4, the radio base station 401 includes two antennas 100. However, these quantities are examples, and are not limited to the quantities in FIG. Even if the high-speed moving body 501 and the high-speed moving body 502 are located at the same position, the high-speed moving body 501 and the high-speed moving body 502 travel in different directions, and correction for different Doppler shifts is performed.

  The wireless communication system 801 in this embodiment includes a plurality of wireless terminals 301, 302,... And a wireless base station 401.

  FIG. 5 is a block diagram illustrating an example of a configuration of a wireless terminal according to the second embodiment of the present invention.

  Each of the wireless terminals 301, 302,... According to the present embodiment receives a downlink signal from the wireless base station 401 and transmits an uplink signal to the wireless base station 401. Each of the wireless terminals 301, 302,... Has a possibility of being moved by the high-speed moving bodies 501, 502,. Each of the wireless terminals 301, 302,... Includes an antenna 200, a duplexer 201, a received signal RF processing unit 202, a signal digital processing unit 203, a baseband unit 204, and a transmission signal RF processing unit 205. including.

  The antenna 200 converts downstream radio waves into downstream RF signals and converts upstream RF signals into upstream radio waves.

  The duplexer 201 electrically separates the downstream RF signal and the upstream RF signal.

  The reception signal RF processing unit 202 filters the downlink RF signal, amplifies the filtered downlink RF signal, and outputs the amplified downlink RF signal.

The signal digital processing unit 203
(1) Demodulate the downlink RF signal output by the received signal RF processing unit 202 into a downlink baseband signal,
(2) filtering the demodulated downlink baseband signal;
(3) The filtered downlink baseband signal is converted into a downlink symbol by A / D (Analog to Digital) conversion,
(4) Output downlink data corresponding to the converted downlink symbol.

The signal digital processing unit 203
(5) The frequency of the uplink RF signal is determined by subtracting a predetermined frequency difference from the frequency of the downlink RF signal output by the received signal RF processing unit 202 (AFC function).

  The baseband unit 204 receives the downlink data output from the signal digital processing unit 203, generates uplink data by performing necessary protocol stack processing, and outputs the generated uplink data. The baseband unit 204 controls the entire wireless terminal 301.

The signal digital processing unit 203
(6) The uplink data output from the baseband unit 204 is converted into a corresponding uplink symbol,
(7) Convert the converted uplink symbol into an upstream baseband signal by D / A (Digital to Analog) conversion,
(8) filtering the converted upstream baseband signal;
(9) Modulate the filtered uplink baseband signal into an uplink RF signal, and output the modulated uplink RF signal.

  The transmission signal RF processing unit 205 amplifies the uplink RF signal output from the signal digital processing unit 203, filters the amplified uplink RF signal, and outputs the filtered uplink RF signal.

  Note that the processing (4) and (6) in the signal digital processing unit 203 may be executed by the baseband unit 204. Further, the modulation method in (1) and (9) of the signal digital processing unit 203 is, for example, OFDM (Orthogonal Frequency Division Multiplex).

  FIG. 6 is a block diagram illustrating an example of a configuration of a radio base station according to the second embodiment of the present invention.

  The radio base station 401 of this embodiment transmits a downlink signal to the radio terminal 301 and receives an uplink signal from the radio terminal 301. The radio base station 401 has a certain cell 601 including a part of the moving path of the high-speed moving body 501 and a certain cell 602 including a part of the moving path of the high-speed moving body 502. The radio base station 401 includes an antenna 100, a duplexer 101, a received signal RF processing unit 102, a received signal digital processing unit 103, a baseband unit 104, a timing control unit 105, and a transmission signal digital processing unit 106. The transmission signal RF processing unit 107 and the Doppler shift correction unit 108 are included.

  The antenna 100 converts upstream radio waves into upstream RF signals, and converts downstream RF signals into downstream radio waves.

  The duplexer 101 electrically separates the upstream RF signal and the downstream RF signal.

  The reception signal RF processing unit 102 filters the uplink RF signal, amplifies the filtered uplink RF signal, and outputs the amplified uplink RF signal.

The received signal digital processing unit 103
(1) Demodulate the uplink RF signal output from the received signal RF processing unit 102 into an uplink baseband signal,
(2) filtering the demodulated uplink baseband signal;
(3) The filtered uplink baseband signal is converted into an uplink symbol by A / D conversion,
(4) Output uplink data corresponding to the converted uplink symbol.

  The baseband unit 104 receives the uplink data output from the received signal digital processing unit 103, generates downlink data by performing necessary protocol stack processing, and outputs the generated downlink data. Further, the baseband unit 104 performs overall control of the radio base station 401.

  The timing control unit 105 outputs a reference clock signal used for modulation and demodulation of the RF signal.

The transmission signal digital processing unit 106
(5) The downlink data output by the baseband unit 104 is converted into a corresponding downlink symbol,
(6) The converted downlink symbol is converted into a downlink baseband signal by D / A conversion,
(7) filtering the converted downstream baseband signal;
(8) Modulate the filtered downlink baseband signal into a downlink RF signal and output the modulated downlink RF signal.

  The transmission signal RF processing unit 107 amplifies the downlink RF signal output from the transmission signal digital processing unit 106, filters the amplified downlink RF signal, and outputs the filtered downlink RF signal.

  The Doppler shift correction unit 108 is a reference supplied from the timing control unit 105 to the transmission signal digital processing unit 106 based on the location information and terminal identifier information of the wireless terminal 301 when the wireless terminal 301 exists in the cell 601. Correct the clock signal.

  Note that the process (4) in the received signal digital processing unit 103 and the process (6) in the transmitted signal digital processing unit 106 may be executed by the baseband unit 104. Also, the modulation method in (1) of the received signal digital processing unit 103 and (8) of the transmission signal digital processing unit 106 is, for example, OFDM.

FIG. 7 is a diagram illustrating the occurrence of a Doppler shift in the second embodiment of the present invention. Here, F _ds represents the frequency of the downlink signal transmitted by the antenna 100 of the radio base station 401, and F _dr represents the frequency of the downlink signal received by the antenna 200 of the radio terminal 301. Further, _Fus represents the frequency of the uplink signal transmitted by the antenna 200 of the radio terminal 301, and _Fur represents the frequency of the uplink signal received by the antenna 100 of the radio base station 401. Further, F _d0 represents a downlink reference frequency, and F _u0 represents an uplink reference frequency. Further, f _d represents the Doppler shift amount when the antenna 200 of the radio terminal 301 receives the downlink signal, and f _u represents the Doppler shift amount when the antenna 100 of the radio base station 401 receives the uplink signal. .

  First, a case where the Doppler shift correction unit 108 does not correct the Doppler shift will be described.

First, the radio base station 401 transmits a downlink signal having a frequency F _ds (= down _link reference (F _d0 )).

Next, the wireless terminal 301 receives the downlink signal at the frequency F _dr (= F _d0 + f _d ) affected by the Doppler shift in the downlink signal by the antenna 200.

Subsequently, the signal digital processing unit 203 receives the downlink signal via the duplexer 201 and the reception signal RF processing unit 202, and synchronizes with the frequency F _dr (= F _d0 + f _d ) by the AFC function, and the uplink signal At a frequency F _ur (= F _u0 + f _d ). Here, the signal digital processing unit 203 subtracts a predetermined frequency difference (F _d0 −F _u0 ) from the frequency F _dr (= F _d0 + f _d ) of the received downlink signal to thereby increase the frequency F _us (= (F _u0 + f _d ) is determined.

Subsequently, the radio base station 401 receives the uplink signal at the frequency F _ur (= F _u0 + f _d + _{fu )} that is further influenced by the Doppler shift in the uplink signal by the antenna 100. That is, the Doppler shift correction unit 108, it is necessary to correct the Doppler shift of the shift frequency _f d + _{f u.}

  Next, a case where the Doppler shift correction unit 108 corrects the Doppler shift will be described.

The Doppler shift correction unit 108 corrects a signal obtained by correcting the reference clock signal input from the timing control unit 105 so as to decrease the reference clock signal by an amount corresponding to the downstream and upstream transition frequencies (f _d + f _u ). To 106.

Next, the transmission signal digital processing unit 106, output by the Doppler shift correction unit 108, based on the corrected reference clock signal, the frequency _{F ds (= F d0 - (} f u + f d)) a downlink signal in Send.

Subsequently, the wireless terminal 301 receives downlink signals at the frequency _{F dr (= F d0 -f u} ).

Subsequently, the wireless terminal 301 transmits uplink signals at the frequency _{F us (= F u0 -f u} ).

Subsequently, the radio base station 401 receives a downlink signal at the frequency F _ur (= F _u0 ).

  Here, the baseband unit 104 is a portion that cannot be uniformly corrected by the Doppler shift correction unit 108, such as frequency fluctuations associated with the movement of the wireless terminal in the high-speed moving body 501 among the change in frequency due to the Doppler shift. May be individually corrected for each terminal.

Further, the Doppler shift correction unit 108 calculates in advance downlink and uplink transition frequencies (f _d + f _u ) based on the position and speed of the wireless terminal 301 existing in the cell 601. For example, the Doppler shift correction unit 108 acquires in advance position information indicating the time when the wireless terminal 301 exists at each of the positions 704, 705,... Shown in FIG. Then, the Doppler shift correction unit 108 estimates the current position (position 703) and speed of the wireless terminal 301 based on the position information of the wireless terminal 301. Then, the Doppler shift correction unit 108 calculates the current position (position 703) and change in speed frequency _(f d + f _u).

The Doppler shift correction unit 108 calculates the downstream and upstream transition frequencies (f _d + f _u ) using Equations 3 and 4. However, the speed c is the speed of light, the speed v is the speed of the wireless terminal 301 with respect to the antenna 100, and the angle θ is the moving direction of the wireless terminal 301 with respect to the antenna 100. Further, it is assumed that the angle is 0 degree when the wireless terminal 301 approaches the antenna 100 straight and 180 degrees when the wireless terminal 301 moves straight away from the antenna 100. Note that the speed v is the current speed of the wireless terminal 301, and the angle θ can be calculated from the position of the antenna 100 of the wireless base station 401 and the current position of the wireless terminal 301.

  The location information of the wireless terminal 301 may be transmitted from the wireless terminal 301 to the wireless base station 401. Here, the position information is transmitted using, for example, an MDT (Minimization of Drive Tests) function of the wireless terminal 301. Alternatively, the location information of the wireless terminal 301 may be measured by the wireless base station 401. Alternatively, the location information of the wireless terminal 301 is received or measured by the wireless base station in which the wireless terminal 301 has been in the past, and the wireless base station 401 newly entering from the previous wireless base station at the time of handover is newly entered. May be taken over. Alternatively, when the operation information of the high-speed moving body 501 (information indicating the position and speed at each position of the high-speed moving body) is available, such as when the high-speed moving body 501 is a bullet train, the position information is calculated from the operation information. May be. Note that the information regarding which wireless terminal the position information is related to the position information may be identified by, for example, information on the terminal identifier of the wireless terminal associated with the position information. The terminal identifier is, for example, IMSI (International Mobile Subscriber Identity).

  Other configurations in the present embodiment are the same as those in the first embodiment.

  The operation in this embodiment will be described.

  FIG. 8 is a flowchart showing the operation of the radio communication system according to the second embodiment of the present invention. Note that the flowchart shown in FIG. 8 and the following description are examples, and the processing order and the like may be changed, the processing may be returned, or the processing may be repeated depending on the processing that is appropriately obtained.

  First, the radio base station 401 acquires the position information and terminal identification information of the radio terminal 301 (step S100).

Next, the Doppler shift correction unit 108 of the radio base station 401 uses the frequency F _d0 − ( _fu + f _d ) obtained by subtracting the sum (f _d + _fu ) of the uplink and downlink variation frequencies from the downlink reference frequency F _d0 −. A downlink signal is transmitted (step S110).

Subsequently, the wireless terminal 301 receives downlink signals at the frequency _F d0 -f _u (step S120).

Wireless terminal 301, the frequency of the uplink signal to determine a reference frequency _F d0 -f _u downlink signal received (frequency _F u0 _-f u) (step S130).

Wireless terminal 301 transmits uplink signals at the frequency _F u0 -f _u (step S140).

The radio base station 401 receives the uplink signal (frequency is F _u0 ) (step S150).

  Other operations in the present embodiment are the same as those in the first embodiment.

  As described above, in the wireless communication system 801 of this embodiment, the wireless base station 401 includes the Doppler shift correction unit 108. Then, the Doppler shift correction unit 108 generates the moving speed information of the wireless terminal 301 at the present time. And the Doppler shift correction | amendment part 108 is a frequency of the frequency by Doppler shift with respect to all the radio | wireless terminals which exist in the cell 601 among several radio | wireless terminals 301,302, ... based on moving speed information. Compensate for changes. Here, the Doppler shift correction unit 108 does not correct the frequency change due to the Doppler shift for each wireless terminal existing in the cell 601, but uniformly applies the Doppler shift to all wireless terminals existing in the cell 601. Corrects the frequency change caused by. In addition, the wireless communication system 801 does not include special devices other than the wireless terminals 301, 302,... And the wireless base station 401. Therefore, the wireless communication system 801 according to the present embodiment has an effect that the load on the baseband processing unit related to the Doppler shift correction generated between the mobile terminal moving at high speed can be suppressed at a low cost.

  The radio base station 401 may further include a beam forming unit (not shown). The beam forming unit causes the position of the beam (cell 601) to follow the position of the wireless terminal 301 using a beam forming technique. The beam forming unit concentrates the radio wave beam in the direction in which the wireless terminal exists by adjusting the phase of the radio wave radiated using the phased array antenna disclosed in Patent Document 3, for example, as the antenna 100. When the radio base station 401 includes a beam forming unit, the Doppler shift can be easily corrected even when a plurality of high-speed moving bodies 501 and 502 having different moving speeds or different moving directions exist close to each other. There is an effect. Further, when the radio base station 401 includes a beam forming unit, there is an effect that a different cell can be set for each different position (for example, each vehicle of a train) in a certain high-speed moving body. Further, the antenna 100 may be, for example, a multi-beam antenna that forms a plurality of beams by one array antenna.

  FIG. 9 is a block diagram showing an example of a hardware configuration capable of realizing the radio base station in each embodiment of the present invention.

  The radio base station 907 includes a storage device 902, a CPU (Central Processing Unit) 903, a keyboard 904, a monitor 905, and an I / O (Input / Output) device 908, which are connected by an internal bus 906. ing. The storage device 902 stores operation programs for the CPU 903 such as the Doppler shift correction unit 108, the Doppler shift correction unit 158, and the moving speed calculation unit 160. The CPU 903 controls the entire radio base station 907, executes an operation program stored in the storage device 902, executes programs such as the autonomous control unit 1155 and transmits / receives data via the I / O device 908. The internal configuration of the radio base station 907 is an example. The wireless base station 907 may have a device configuration that connects a keyboard 904 and a monitor 905 as necessary.

  The radio base station in each of the embodiments of the present invention described above may be realized by a dedicated device, but a computer (information processing device) other than the hardware operation in which the I / O device 908 performs communication with the outside. ). In each embodiment of the present invention, the I / O device 908 is, for example, an input / output unit for the antenna 100 and the antenna 150. In this case, the computer reads the software program stored in the storage device 902 to the CPU 903 and executes the read software program in the CPU 903. In the case of each of the embodiments described above, the software program only needs to be described so as to realize the functions of the respective units of the radio base station shown in FIGS. However, it is assumed that these units include hardware as appropriate. In such a case, the software program (computer program) can be regarded as constituting the present invention. Furthermore, a computer-readable storage medium storing such a software program can also be understood as constituting the present invention.

  The present invention has been exemplarily described with the above-described embodiments and modifications thereof. However, the technical scope of the present invention is not limited to the scope described in the above-described embodiments and modifications thereof. It will be apparent to those skilled in the art that various modifications and improvements can be made to such embodiments. In such a case, new embodiments to which such changes or improvements are added can also be included in the technical scope of the present invention. This is apparent from the matters described in the claims.

A part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.
(Appendix 1)
A terminal antenna,
A terminal-side wireless communication means for receiving a downlink signal at a terminal-side reception frequency and transmitting an uplink signal at a terminal-side transmission frequency via the terminal-side antenna;
A plurality of wireless terminals that can be moved by a high-speed moving body;
A base station antenna,
Via the base station side antenna, when the terminal side antenna is stationary with respect to the base station side antenna, transmit the downlink signal at a base station side transmission frequency equal to the terminal side reception frequency, Base station side wireless communication means for receiving the uplink signal at a base station side reception frequency equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna;
A radio base station included in a radio communication system comprising: a radio base station having a cell including a part of a moving path of the certain high-speed mobile body,
A moving speed calculating means for generating moving speed information representing a moving speed and a direction of the terminal of the plurality of wireless terminals at the present time with respect to the base station side antenna;
The base station-side wireless communication means, when the certain terminal exists in the certain cell, determines all terminals present in the certain cell among the plurality of wireless terminals based on the moving speed information. On the other hand, a downlink shift frequency obtained by subtracting the downlink reference frequency of the downlink signal from the frequency of the downlink signal in which the downlink reference frequency has changed due to Doppler shift accompanying the movement of the certain terminal with respect to the base station antenna, and An uplink shift frequency obtained by subtracting the uplink reference frequency of the uplink signal from the frequency of the uplink signal in which the uplink reference frequency has changed due to the Doppler shift is calculated, and based on the calculated downlink shift frequency and the uplink shift frequency A radio base station provided with Doppler shift correction means for correcting a change in frequency due to Doppler shift.
(Appendix 2)
The terminal side wireless communication means determines the terminal side transmission frequency by subtracting a predetermined frequency difference from the terminal side reception frequency,
The Doppler shift correction means subtracts a sum of the downlink shift frequency and the uplink shift frequency from the downlink reference frequency in the certain cell when the certain terminal exists in the certain cell. The radio base station according to appendix 1, which determines a station-side transmission frequency.
(Appendix 3)
The Doppler shift correction means, when the certain terminal exists in the certain cell, in the certain cell,
The base station side transmission frequency is determined by subtracting the downlink transition frequency from the downlink reference frequency,
The radio base station according to supplementary note 1, wherein the uplink signal received from each of all the terminals is corrected as a signal in which the uplink reference frequency is changed by the uplink shift frequency.
(Appendix 4)
The moving speed calculation means generates the moving speed information based on a plurality of sets of information on a position where the certain terminal exists and information on a time when the certain terminal exists at the position. The radio base station according to any one of the above.
(Appendix 5)
The wireless base station according to any one of appendices 1 to 4, wherein the moving speed calculation means generates the moving speed information based on operation information of the certain high-speed moving body.
(Appendix 6)
The said certain cell is any one of the supplementary notes 1 to 5 set so that all the terminals which exist in the said certain cell among the said radio | wireless terminals were moved by the said certain high-speed moving body. Wireless base station.
(Appendix 7)
7. The radio base station according to any one of appendices 1 to 6, further comprising beam forming means for causing the position of the certain cell to follow the movement of the certain terminal.
(Appendix 8)
A terminal antenna,
A terminal-side wireless communication means for receiving a downlink signal at a terminal-side reception frequency and transmitting an uplink signal at a terminal-side transmission frequency via the terminal-side antenna;
A plurality of wireless terminals that can be moved by a high-speed moving body;
A base station antenna,
Via the base station side antenna, when the terminal side antenna is stationary with respect to the base station side antenna, transmit the downlink signal at a base station side transmission frequency equal to the terminal side reception frequency, Base station side wireless communication means for receiving the uplink signal at a base station side reception frequency equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna;
A radio base station having a cell including a part of a moving path of the certain high-speed moving body,
The radio base station further includes a moving speed calculation unit that generates moving speed information indicating a moving speed and a direction of a certain terminal of the plurality of radio terminals with respect to the base station side antenna at the present time,
The base station-side wireless communication means, when the certain terminal exists in the certain cell, determines all terminals present in the certain cell among the plurality of wireless terminals based on the moving speed information. On the other hand, a downlink shift frequency obtained by subtracting the downlink reference frequency of the downlink signal from the frequency of the downlink signal in which the downlink reference frequency has changed due to Doppler shift accompanying the movement of the certain terminal with respect to the base station antenna, and An uplink shift frequency obtained by subtracting the uplink reference frequency of the uplink signal from the frequency of the uplink signal in which the uplink reference frequency has changed due to the Doppler shift is calculated, and based on the calculated downlink shift frequency and the uplink shift frequency A wireless communication system including Doppler shift correction means for correcting a change in frequency due to Doppler shift.
(Appendix 9)
A terminal antenna,
A terminal-side wireless communication means for receiving a downlink signal at a terminal-side reception frequency and transmitting an uplink signal at a terminal-side transmission frequency via the terminal-side antenna;
A plurality of wireless terminals that can be moved by a high-speed moving body;
A base station antenna,
Via the base station side antenna, when the terminal side antenna is stationary with respect to the base station side antenna, transmit the downlink signal at a base station side transmission frequency equal to the terminal side reception frequency, Base station side wireless communication means for receiving the uplink signal at a base station side reception frequency equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna;
A control method for the radio base station included in a radio communication system comprising: a radio base station having a certain cell including a part of a moving path of the certain high-speed moving body,
The wireless base station generates movement speed information indicating a movement speed and direction of a terminal of the plurality of wireless terminals at the present time with respect to the base station side antenna,
When the certain terminal exists in the certain cell by the base station side wireless communication means, all the terminals present in the certain cell among the plurality of wireless terminals are determined based on the moving speed information. On the other hand, a downlink shift frequency obtained by subtracting the downlink reference frequency of the downlink signal from the frequency of the downlink signal in which the downlink reference frequency has changed due to Doppler shift accompanying the movement of the certain terminal with respect to the base station antenna, and An uplink shift frequency obtained by subtracting the uplink reference frequency of the uplink signal from the frequency of the uplink signal in which the uplink reference frequency has changed due to the Doppler shift is calculated, and based on the calculated downlink shift frequency and the uplink shift frequency A control method that corrects frequency changes due to Doppler shift.
(Appendix 10)
A terminal antenna,
A terminal-side wireless communication means for receiving a downlink signal at a terminal-side reception frequency and transmitting an uplink signal at a terminal-side transmission frequency via the terminal-side antenna;
A plurality of wireless terminals that can be moved by a high-speed moving body;
A base station antenna,
Via the base station side antenna, when the terminal side antenna is stationary with respect to the base station side antenna, transmit the downlink signal at a base station side transmission frequency equal to the terminal side reception frequency, Base station side wireless communication means for receiving the uplink signal at a base station side reception frequency equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna;
A computer included in the wireless base station, included in a wireless communication system including a wireless base station having a cell including a part of a moving path of the certain high-speed moving body,
A moving speed calculation process for generating moving speed information representing a moving speed and a direction of the terminal of the plurality of wireless terminals at the present time with respect to the base station side antenna;
When the certain terminal exists in the certain cell by the base station side wireless communication means, all the terminals present in the certain cell among the plurality of wireless terminals are determined based on the moving speed information. On the other hand, a downlink shift frequency obtained by subtracting the downlink reference frequency of the downlink signal from the frequency of the downlink signal in which the downlink reference frequency has changed due to Doppler shift accompanying the movement of the certain terminal with respect to the base station antenna, and An uplink shift frequency obtained by subtracting the uplink reference frequency of the uplink signal from the frequency of the uplink signal in which the uplink reference frequency has changed due to the Doppler shift is calculated, and based on the calculated downlink shift frequency and the uplink shift frequency A control program that executes Doppler shift correction processing that corrects frequency changes due to Doppler shift .
(Appendix 11)
The base station-side radio communication means has a portion of the change in frequency due to the Doppler shift that cannot be corrected uniformly by the Doppler shift correction means in the certain cell of the plurality of radio terminals. 8. The radio base station according to any one of appendices 1 to 7, wherein correction is performed individually for each terminal.
(Appendix 12)
Any one of Supplementary notes 1 to 7, wherein the certain cell is set so that a direction of the certain terminal with respect to the base station side antenna is approximately constant while the certain terminal passes through the certain cell. Item 12. or radio base station according to appendix 11.
(Appendix 13)
The absolute value of the predetermined frequency difference is sufficiently smaller than the uplink reference frequency and the downlink reference frequency,
The Doppler shift correction means calculates either the downlink shift frequency or the uplink shift frequency, and calculates the sum by doubling the calculated downlink shift frequency or the uplink shift frequency. The radio base station according to appendix 2.
(Appendix 14)
The terminal-side wireless communication means calculates the terminal-side transmission frequency by subtracting a predetermined frequency difference from the terminal-side reception frequency,
The Doppler shift correction means subtracts a sum of the downlink shift frequency and the uplink shift frequency from the downlink reference frequency in the certain cell when the certain terminal exists in the certain cell. Item 9. The wireless communication system according to appendix 8, which determines a station-side transmission frequency.
(Appendix 15)
The terminal side radio communication means calculates the terminal side transmission frequency by subtracting a predetermined frequency difference from the terminal side reception frequency,
By subtracting the sum of the downlink shift frequency and the uplink shift frequency from the downlink reference frequency in the certain cell when the certain terminal exists in the certain cell by the base station side wireless communication means The control method according to appendix 9, wherein the base station side transmission frequency is determined.
(Appendix 16)
The terminal-side wireless communication means calculates the terminal-side transmission frequency by subtracting a predetermined frequency difference from the terminal-side reception frequency,
The Doppler shift correction processing is performed by subtracting a sum of the downlink shift frequency and the uplink shift frequency from the downlink reference frequency in the certain cell when the certain terminal exists in the certain cell. The control program according to appendix 10, which determines a station-side transmission frequency.

  INDUSTRIAL APPLICABILITY The present invention can be used for correcting a Doppler shift caused by movement of a wireless mobile station in a wireless communication system.

100, 150 Antenna 159 Radio communication unit 158 Doppler shift correction unit 160 Movement speed calculation unit 200, 250 Antenna 259 Radio communication unit 301, 302, 305, 306 Radio terminal 401, 405 Radio base station 501, 502 High-speed mobile 601, 602 , 605 cell 805 wireless communication system 811 movement path 902 storage device 903 CPU
904 Keyboard 905 Monitor 906 Internal bus 907 Wireless base station 908 I / O device

Claims (10)

A terminal antenna,
A terminal-side wireless communication means for receiving a downlink signal at a terminal-side reception frequency and transmitting an uplink signal at a terminal-side transmission frequency via the terminal-side antenna;
A plurality of wireless terminals that can be moved by a high-speed moving body;
A base station antenna,
Via the base station side antenna, when the terminal side antenna is stationary with respect to the base station side antenna, transmit the downlink signal at a base station side transmission frequency equal to the terminal side reception frequency, Base station side wireless communication means for receiving the uplink signal at a base station side reception frequency equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna;
A radio base station included in a radio communication system comprising: a radio base station having a cell including a part of a moving path of the certain high-speed mobile body,
A moving speed calculating means for generating moving speed information representing a moving speed and a direction of the terminal of the plurality of wireless terminals at the present time with respect to the base station side antenna;
The base station-side wireless communication means, when the certain terminal exists in the certain cell, determines all terminals present in the certain cell among the plurality of wireless terminals based on the moving speed information. On the other hand, a downlink shift frequency obtained by subtracting the downlink reference frequency of the downlink signal from the frequency of the downlink signal in which the downlink reference frequency has changed due to Doppler shift accompanying the movement of the certain terminal with respect to the base station antenna, and An uplink shift frequency obtained by subtracting the uplink reference frequency of the uplink signal from the frequency of the uplink signal in which the uplink reference frequency has changed due to the Doppler shift is calculated, and based on the calculated downlink shift frequency and the uplink shift frequency A radio base station provided with Doppler shift correction means for correcting a change in frequency due to Doppler shift. The terminal side wireless communication means determines the terminal side transmission frequency by subtracting a predetermined frequency difference from the terminal side reception frequency,
The Doppler shift correction means subtracts a sum of the downlink shift frequency and the uplink shift frequency from the downlink reference frequency in the certain cell when the certain terminal exists in the certain cell. The radio base station according to claim 1, wherein a station-side transmission frequency is determined. The Doppler shift correction means, when the certain terminal exists in the certain cell, in the certain cell,
The base station side transmission frequency is determined by subtracting the downlink transition frequency from the downlink reference frequency,
The radio base station according to claim 1, wherein the uplink signal received from each of all the terminals is corrected as a signal in which the uplink reference frequency is changed by the uplink shift frequency. The moving speed calculation unit generates the moving speed information based on a plurality of sets of information on a position where the certain terminal exists and information on a time when the certain terminal exists at the position. 4. The radio base station according to any one of 3. 5. The radio base station according to claim 1, wherein the moving speed calculation unit generates the moving speed information based on operation information of the certain high-speed moving body. The said certain cell is set to any one of Claims 1 thru | or 5 set so that all the terminals which exist in the said certain cell among the said radio | wireless terminals may be moved by the said certain high-speed moving body. The radio base station described. The radio base station according to any one of claims 1 to 6, further comprising beam forming means for causing the position of the certain cell to follow the movement of the certain terminal. A terminal antenna,
A terminal-side wireless communication means for receiving a downlink signal at a terminal-side reception frequency and transmitting an uplink signal at a terminal-side transmission frequency via the terminal-side antenna;
A plurality of wireless terminals that can be moved by a high-speed moving body;
A base station antenna,
Via the base station side antenna, when the terminal side antenna is stationary with respect to the base station side antenna, transmit the downlink signal at a base station side transmission frequency equal to the terminal side reception frequency, Base station side wireless communication means for receiving the uplink signal at a base station side reception frequency equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna;
A radio base station having a cell including a part of a moving path of the certain high-speed moving body,
The radio base station further includes a moving speed calculation unit that generates moving speed information indicating a moving speed and a direction of a certain terminal of the plurality of radio terminals with respect to the base station side antenna at the present time,
The base station-side wireless communication means, when the certain terminal exists in the certain cell, determines all terminals present in the certain cell among the plurality of wireless terminals based on the moving speed information. On the other hand, a downlink shift frequency obtained by subtracting the downlink reference frequency of the downlink signal from the frequency of the downlink signal in which the downlink reference frequency has changed due to Doppler shift accompanying the movement of the certain terminal with respect to the base station antenna, and An uplink shift frequency obtained by subtracting the uplink reference frequency of the uplink signal from the frequency of the uplink signal in which the uplink reference frequency has changed due to the Doppler shift is calculated, and based on the calculated downlink shift frequency and the uplink shift frequency A wireless communication system including Doppler shift correction means for correcting a change in frequency due to Doppler shift. A terminal antenna,
A terminal-side wireless communication means for receiving a downlink signal at a terminal-side reception frequency and transmitting an uplink signal at a terminal-side transmission frequency via the terminal-side antenna;
A plurality of wireless terminals that can be moved by a high-speed moving body;
A base station antenna,
Via the base station side antenna, when the terminal side antenna is stationary with respect to the base station side antenna, transmit the downlink signal at a base station side transmission frequency equal to the terminal side reception frequency, Base station side wireless communication means for receiving the uplink signal at a base station side reception frequency equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna;
A control method for the radio base station included in a radio communication system comprising: a radio base station having a certain cell including a part of a moving path of the certain high-speed moving body,
The wireless base station generates movement speed information indicating a movement speed and direction of a terminal of the plurality of wireless terminals at the present time with respect to the base station side antenna,
When the certain terminal exists in the certain cell by the base station side wireless communication means, all the terminals present in the certain cell among the plurality of wireless terminals are determined based on the moving speed information. On the other hand, a downlink shift frequency obtained by subtracting the downlink reference frequency of the downlink signal from the frequency of the downlink signal in which the downlink reference frequency has changed due to Doppler shift accompanying the movement of the certain terminal with respect to the base station antenna, and An uplink shift frequency obtained by subtracting the uplink reference frequency of the uplink signal from the frequency of the uplink signal in which the uplink reference frequency has changed due to the Doppler shift is calculated, and based on the calculated downlink shift frequency and the uplink shift frequency A control method that corrects frequency changes due to Doppler shift. A terminal antenna,
A terminal-side wireless communication means for receiving a downlink signal at a terminal-side reception frequency and transmitting an uplink signal at a terminal-side transmission frequency via the terminal-side antenna;
A plurality of wireless terminals that can be moved by a high-speed moving body;
A base station antenna,
Via the base station side antenna, when the terminal side antenna is stationary with respect to the base station side antenna, transmit the downlink signal at a base station side transmission frequency equal to the terminal side reception frequency, Base station side wireless communication means for receiving the uplink signal at a base station side reception frequency equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna;
A computer included in the wireless base station, included in a wireless communication system including a wireless base station having a cell including a part of a moving path of the certain high-speed moving body,
A moving speed calculation process for generating moving speed information representing a moving speed and a direction of the terminal of the plurality of wireless terminals at the present time with respect to the base station side antenna;
When the certain terminal exists in the certain cell by the base station side wireless communication means, all the terminals present in the certain cell among the plurality of wireless terminals are determined based on the moving speed information. On the other hand, a downlink shift frequency obtained by subtracting the downlink reference frequency of the downlink signal from the frequency of the downlink signal in which the downlink reference frequency has changed due to Doppler shift accompanying the movement of the certain terminal with respect to the base station antenna, and An uplink shift frequency obtained by subtracting the uplink reference frequency of the uplink signal from the frequency of the uplink signal in which the uplink reference frequency has changed due to the Doppler shift is calculated, and based on the calculated downlink shift frequency and the uplink shift frequency A control program that executes Doppler shift correction processing that corrects frequency changes due to Doppler shift .

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