JP6822221B2 - Radio base stations, wireless communication systems, and control methods and programs for wireless base stations - Google Patents

Description

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

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

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

An example of a technique for correcting Doppler shift is disclosed in Patent Document 1. The mobile communication system of Patent Document 1 includes a base station device (radio base station) and a mobile station device (wireless terminal). The base station apparatus includes a phase error detecting unit and a phase error rotating unit. The phase error detection unit detects the phase error caused by the Doppler shift in the received wave from each mobile station device. The phase error rotating unit is a transmission symbol in the base band region so that the Doppler shift that occurs in the downlink from the base station equipment to each mobile station equipment is canceled based on the phase error detected by the phase error detecting unit. Rotate the phase of. 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 cancelled.

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

When a large number of wireless terminals are present inside a mobile body moving at high speed such as the Shinkansen, the load caused by the correction of the Doppler shift in the wireless base station becomes particularly large.

The wireless communication system of Patent Document 2 includes a wireless base station, a user terminal (wireless terminal), and a joint receiving device, and the wireless base station uses beamforming to follow the movement of the user terminal. The user terminal and the joint receiving device exist inside the mobile body. The user terminal transfers the signal received from the radio base station to the joint receiving device. Then, the joint receiving device performs signal detection processing of 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 receiving device. As a result of the above configuration, the wireless communication system of Patent Document 2 suppresses interference between terminals due to an increase in the number of moving user terminals and suppresses deterioration of communication performance.

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

JP-A-2007-81952 Japanese Unexamined Patent Publication No. 2015-126473 Japanese Unexamined Patent Publication No. 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 signals are exchanged and optimized between the joint receiving device and the user terminal, the processing becomes complicated and the processing becomes complicated. As the load increases, the configuration is not inexpensive.

The present invention has been made in view of the above problems, and the main object of the present invention is to inexpensively suppress the load of the baseband processing unit for Doppler shift correction generated between the terminal inside the moving body moving at high speed. And.

In one aspect of the present invention, the radio base station receives a downlink signal at the terminal-side reception frequency and transmits an uplink signal at the 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 having a possibility of being moved by a high-speed moving body including means, a base station side antenna, and a base station side antenna. When the antenna is stationary, the downlink signal is transmitted at the base station side transmission frequency, which is equal to the terminal side reception frequency, and when the terminal side antenna is stationary with respect to the base station side antenna, the base station is equal to the terminal side transmission frequency. A radio base included in a radio communication system including a base station side radio communication means for receiving an uplink signal at a side reception frequency and a radio base station having a cell including a part of a movement path of a high-speed mobile body. The station is further provided with a moving speed calculation means for generating moving speed information indicating the moving speed and direction of a certain terminal among a plurality of wireless terminals with respect to the base station side antenna, and the base station side wireless communication means. When a certain terminal exists in a certain cell, the downlink reference frequency of the downlink signal is uniformly set for all the terminals existing in the cell among a plurality of wireless terminals based on the moving speed information. , The downlink reference frequency changed due to the Doppler shift due to the movement of a certain terminal to the base station side antenna. The downlink transition frequency subtracted from the frequency of the downlink signal and the uplink reference frequency of the uplink signal were changed by the Doppler shift. It is provided with a Doppler shift correction means that calculates an uplink transition frequency subtracted from the frequency of the uplink signal and corrects the frequency change due to the Doppler shift based on the calculated downlink transition frequency and the uplink transition frequency.

In one aspect of the present invention, the wireless communication system is a terminal-side wireless communication that receives a downlink signal at the terminal-side reception frequency and transmits an uplink signal at the 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 having a possibility of being moved by a high-speed moving body including means, 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, which is equal to the terminal side reception frequency. A wireless communication system including a base station side wireless communication means for receiving an uplink signal at a side reception frequency and a wireless base station having a certain cell including a part of a movement path of a certain high-speed mobile body. The base station further includes a moving speed calculation means for generating moving speed information indicating the moving speed and direction of a certain terminal among a plurality of wireless terminals with respect to the base station side antenna, and the base station side wireless communication means , When a certain terminal exists in a certain cell, the downlink reference frequency of the downlink signal is uniformly set for all the terminals existing in a certain cell among a plurality of wireless terminals based on the movement speed information. The downlink reference frequency is changed by the Doppler shift due to the movement of a terminal to the base station side antenna. The downlink transition frequency subtracted from the frequency of the downlink signal and the uplink reference frequency of the uplink signal are changed by the Doppler shift. It is provided with Doppler shift correction that calculates the uplink shift frequency subtracted from the signal frequency and corrects the frequency change due to the Doppler shift based on the calculated downlink shift frequency and uplink shift frequency.

In one aspect of the present invention, the control method is a terminal-side wireless communication means that receives a downlink signal at a terminal-side reception frequency and transmits an uplink signal at a terminal-side transmission frequency via a terminal-side antenna and a terminal-side antenna. The terminal side antenna is stationary with respect to the base station side antenna via a plurality of wireless terminals having a possibility of being moved by a certain high-speed moving body, a base station side antenna, and a base station side antenna. When the downlink signal is transmitted at the base station side transmission frequency, which is equal to the terminal side reception frequency, and when the terminal side antenna is stationary with respect to the base station side antenna, the base station side is equal to the terminal side transmission frequency. A radio base included in a radio communication system including a base station-side radio communication means for receiving an uplink signal at a reception frequency and a radio base station having a cell including a part of a movement path of a high-speed mobile body. This is a station control method, in which a radio base station generates movement speed information indicating the movement speed and direction of a terminal among a plurality of radio terminals with respect to the base station side antenna, and the base station side wireless communication. By means, when a certain terminal exists in a certain cell, the downlink reference frequency of the downlink signal is uniformly applied to all the terminals existing in a certain cell among a plurality of wireless terminals based on the movement speed information. The downlink reference frequency is changed by the Doppler shift due to the movement of a terminal to the base station side antenna. The downlink reference frequency is subtracted from the frequency of the downlink signal, and the uplink reference frequency of the uplink is changed by the Doppler shift. The uplink transition frequency subtracted from the frequency of the uplink signal is calculated, and the frequency change due to the Doppler shift is corrected based on the calculated downlink transition frequency and uplink transition frequency.

In one aspect of the present invention, the control program of the radio base station or the recording medium in which the control program is stored receives the downlink signal at the terminal-side reception frequency via the terminal-side antenna and the terminal-side antenna. Via a plurality of wireless terminals which include a terminal-side wireless communication means for transmitting an uplink signal at a terminal-side transmission frequency and which may be moved by a 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, a 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. A radio having a cell including a part of a moving path of a high-speed mobile body, including a base station side wireless communication means for receiving an uplink signal at a base station side receiving frequency, which is equal to the terminal side transmitting frequency when the antenna is used. A computer included in a wireless base station included in a wireless communication system including a base station is provided with moving speed information indicating the moving speed and direction of a terminal among a plurality of wireless terminals with respect to the base station side antenna at present. When a certain terminal exists in a certain cell by the generated movement speed calculation process and the base station side wireless communication means, all the all existing in a certain cell among a plurality of wireless terminals based on the movement speed information. For the terminal, the downlink reference frequency of the downlink is subtracted from the frequency of the downlink whose downlink reference frequency has changed due to the Doppler shift accompanying the movement of a terminal with respect to the base station side antenna, and the uplink frequency. Doppler that calculates the uplink transition frequency by subtracting the uplink reference frequency from the frequency of the uplink signal whose uplink reference frequency has changed due to Doppler shift, and corrects the frequency change due to Doppler shift based on the calculated downlink transition frequency and uplink transition frequency. The shift correction process is executed.

According to the present invention, there is an effect that the load of the baseband processing unit for Doppler shift correction generated between the terminal inside the moving body moving at high speed can be suppressed at low cost.

It is a block diagram which shows an example of the structure of the wireless communication system in 1st Embodiment of this invention. It is a flowchart which shows the operation of the wireless communication system in 1st Embodiment of this invention. It is a flowchart which shows an example of the operation of the wireless communication system in 1st Embodiment of this invention. It is a block diagram which shows an example of the structure of the wireless communication system in 2nd Embodiment of this invention. It is a block diagram which shows an example of the structure of the wireless terminal in 2nd Embodiment of this invention. It is a block diagram which shows an example of the structure of the radio base station in the 2nd Embodiment of this invention. It is a figure explaining the occurrence of Doppler shift in the 2nd Embodiment of this invention. It is a flowchart which shows the operation of the wireless communication system in 2nd Embodiment of this invention. It is a block diagram which shows an example of the hardware composition which can realize 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 drawings, equivalent components are designated by the same reference numerals, and description thereof will be omitted as appropriate.
(First Embodiment)
The configuration in this 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 the present embodiment includes a plurality of wireless terminals 305, 306, ..., And a wireless base station 405.

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

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

The radio base station 405 has a cell 605 that includes a portion of the travel path 811 of the high speed mobile 501. The radio base station 405 includes an antenna 150, a radio communication unit 159, and a moving speed calculation unit 160.

The wireless 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 _Fur . 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,} the antenna 250 is equal to the base station side reception frequency _{F ur} when is stationary relative to the antenna 150. The wireless communication unit 159 includes a Doppler shift correction unit 158.

The moving speed calculation unit 160 generates the moving speed information of the wireless terminal 305 among the plurality of wireless terminals 305, 306, ... At the present time. The moving speed information represents the moving speed and direction of the wireless terminal 305 with respect to the antenna 150. In the following, a case where the movement speed calculation unit 160 generates the movement speed information of the wireless terminal 305 will be described as an example, but the movement speed calculation unit 160 moves any one of the plurality of wireless terminals 305, 306, ... The speed information may be generated. Alternatively, the moving speed calculation unit 160 may generate moving speed information with respect to the average values of the moving speeds and directions of the plurality of wireless terminals 305, 306, ....

The movement speed calculation unit 160 generates movement speed information based on, for example, a plurality of sets of information on the position where the wireless terminal 305 existed and information on the time when the wireless terminal 305 existed at the position. Alternatively, the movement speed calculation unit 160 generates movement speed information based on, for example, the operation information of the high-speed moving body 501.

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

The operation in this embodiment will be described.

FIG. 2 is a flowchart showing the operation of the wireless communication system according to the first embodiment of the present invention. The flowchart shown in FIG. 2 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 according to the desired processing.

First, the moving speed calculation unit 160 generates the moving speed information of the wireless terminal 305 at the present 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 Calculate f _d . 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. The flowchart shown in FIG. 3 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 according to the desired processing.

An example of the operation of the wireless communication system 805 will be described with reference to FIG. 3A.

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 )) is determined, and a downlink signal is transmitted at the determined frequency (step S126).

Next, the wireless communication unit 259 receives the 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 −fu _u ), thereby causing the terminal side transmission frequency _Fus (= 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 the uplink signal at the reception frequency _Fur (= _Fu0 ) on the base station side (step S156).

Another example of the operation of the wireless communication system 805 will be described with reference to FIG. 3 (B).

First, the Doppler shift correction unit 158 determines the base station side transmission frequency F _ds (= F _d0 −f _d ) by subtracting the downlink transition 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 the downlink signal at the terminal-side reception frequency F _dr (= F _d0 ) (step S137).

Subsequently, the wireless communication unit 259 determines the uplink reference frequency _Fu0 to the terminal-side transmission frequency _Fus (= _Fu0 ), and transmits an uplink signal at the determined frequency (step S147).

Subsequently, the wireless communication unit 159, the base station side reception frequency _{F ur (= F u0 + f} u), receives an uplink signal (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 frequency f _d and the uplink frequency fu _u can be calculated by Equations 1 and 2, respectively. However, it is assumed that 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 temperature is 0 degrees 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 the present embodiment, the wireless base station 405 includes a moving speed calculation unit 160 and a Doppler shift correction unit 158. Then, the moving speed calculation unit 160 generates the moving speed information of the wireless terminal 305 at the present time. Then, the Doppler shift correction unit 158 sets the frequency of the Doppler shift to all the wireless terminals existing in the cell 605 among the plurality of wireless terminals 305, 306, ... Based on the movement speed information. Correct the change. Here, the Doppler shift correction unit 158 does not correct the frequency change due to the Doppler shift for each wireless terminal existing in the cell 605, but uniformly shifts the Doppler to all the wireless terminals existing in the cell 605. Corrects the change in frequency due to. Further, the wireless communication system 805 does not include any special device 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 of the baseband processing unit for Doppler shift correction generated between the wireless communication system 805 and the terminal inside the mobile body moving at high speed can be suppressed at low cost.

In addition, the wireless communication unit 159 in the cell 605 of the plurality of wireless terminals 305, 306, ..., Of the frequency changes due to the Doppler shift, the portion that could not be uniformly corrected by the Doppler shift correction unit 158. It may be corrected individually for each terminal existing in. Generally, the correction for the Doppler shift for each radio terminal is performed in the baseband portion of the radio base station. Further, the smaller the change in frequency due to the Doppler shift, the smaller the processing load due to the correction for the Doppler shift. Therefore, in this case, the wireless communication system 805 of the present embodiment has an effect that the load on the wireless base station due to the correction for each terminal for the Doppler shift in the baseband portion of the wireless base station can be suppressed. A technique for correcting a frequency change due to a Doppler shift for each terminal is disclosed in Patent Document 1, for example, and will not be described in detail here.

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

Further, the cell 605 may be set so that all the terminals existing in the cell 605 of the plurality of wireless terminals 305, 306, ... Are moved by the high-speed mobile 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 can be moved by installing the antenna 150 having strong directivity in the downward direction above the moving path 811. Limited to the range of route 811. In this case, in the wireless communication system 805 of the present embodiment, the frequency of the terminal not moved by the high-speed mobile body 501 is corrected by the Doppler shift with respect to the terminal moved by the high-speed mobile body 501. It has the effect of not being applied by mistake.

Further, in the cell 605, the directions of the wireless terminals 305, 306, ... With respect to the antenna 150 are approximately constant while each of the plurality of wireless terminals 305, 306, ... Passes through the cell 605. 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 sufficiently behind the cell 605 in the movement direction of the high-speed moving body 501. As a result, 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 the present embodiment has an effect that it is not necessary to calculate the direction of the wireless terminal 305 with respect to the antenna 150.

Further, 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 transition frequency or the uplink transition frequency. May be calculated. The Doppler shift correction unit 158 calculates, for example, either the downlink frequency or the uplink frequency, and doubles the calculated one to calculate the sum of the downlink frequency and the uplink frequency. May be good. In this case, the wireless communication system 805 of the present embodiment has an effect that the amount of calculation is smaller than that in the case of calculating both the downlink frequency and the uplink frequency.

Further, the radio base station 405 may further include a beamforming unit (not shown) that allows the position of the cell 605 to follow the movement of the radio terminal 305. In this case, in the wireless communication system 805 of the present embodiment, it is easy to 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 beamforming technique is disclosed in Patent Document 3, for example, 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 of the present embodiment, the radio base station adjusts the frequency of the reference clock signal used for modulating the RF (Radio Frequency) signal based on the frequency shift due to the Doppler shift.

The configuration in this embodiment will be described.

FIG. 4 is a block diagram showing an example of the configuration of the 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. Further, in FIG. 4, the movement path 811 is divided into five positions: position 701, position 702, position 703, position 704, and position 705. Further, in FIG. 4, the radio base station 401 includes two antennas 100. However, these quantities are examples, and are not limited to the quantities shown in FIG. Even if the high-speed moving body 501 and the high-speed moving body 502 are present at the same position, they are moving in different directions, and corrections are made for different Doppler shifts.

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

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

Each of the wireless terminals 301, 302, ... Of 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 the possibility of being moved by the high-speed mobile bodies 501, 502, .... The wireless terminals 301, 302, ... Each have 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 the downlink radio wave into a downlink RF signal and also converts the uplink RF signal into an uplink radio wave.

The duplexer 201 electrically separates the downlink RF signal and the uplink 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) The downlink RF signal output by the received signal RF processing unit 202 is demodulated into a downlink baseband signal.
(2) Filter the demodulated downlink baseband signal and
(3) The filtered downlink baseband signal is converted into a downlink symbol by A / D (Analog to Digital) conversion.
(4) Output the downlink data corresponding to the converted downlink symbol.

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

The signal digital processing unit 203
(6) The uplink data output by the baseband section 204 is converted into the corresponding uplink symbol, and then converted.
(7) The converted uplink symbol is converted into an uplink baseband signal by D / A (Digital to Analog) conversion.
(8) Filter the converted uplink baseband signal and
(9) The filtered uplink baseband signal is modulated into an uplink RF signal, and the modulated uplink RF signal is output.

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

The processes (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 showing an example of the configuration of a radio base station according to the second embodiment of the present invention.

The wireless base station 401 of the present embodiment transmits a downlink signal to the wireless terminal 301 and receives an uplink signal from the wireless terminal 301. The radio base station 401 has a cell 601 including a part of the movement path of the high-speed mobile body 501 and a cell 602 including a part of the movement path of the high-speed mobile 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 the uplink radio wave into an uplink RF signal and also converts the downlink RF signal into a downlink radio wave.

The duplexer 101 electrically separates the uplink RF signal and the downlink 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) The uplink RF signal output by the received signal RF processing unit 102 is demodulated into an uplink baseband signal, and then
(2) Filter the demodulated uplink baseband signal and
(3) The filtered uplink baseband signal is converted into an uplink symbol by A / D conversion.
(4) Output the uplink data corresponding to the converted uplink symbol.

The baseband unit 104 receives the uplink data output by 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 controls the entire 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 section 104 is converted into the corresponding downlink symbol, and then converted.
(6) The converted downlink symbol is converted into a downlink baseband signal by D / A conversion.
(7) Filter the converted downlink baseband signal and
(8) The filtered downlink baseband signal is modulated into a downlink RF signal, and the modulated downlink RF signal is output.

The transmission signal RF processing unit 107 amplifies the downlink RF signal output by 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 position information and the terminal identifier information of the wireless terminal 301 when the wireless terminal 301 exists in the cell 601. Correct the clock signal.

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

FIG. 7 is a diagram illustrating the occurrence of 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 wireless terminal 301. Further, _Fu represents the frequency of the uplink signal transmitted by the antenna 200 of the wireless terminal 301, and _Fur represents the frequency of the uplink signal received by the antenna 100 of the wireless base station 401. Further, F _d0 represents a downlink reference frequency, and _{Fu 0} represents an uplink reference frequency. Further, f _d is the Doppler shift amount at the time of receiving the downlink signal antenna 200 of the wireless terminal 301, f _u is a represent the Doppler shift amount at the time of receiving the uplink signal antenna 100 of the radio base station 401 ..

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 of F _ds (= downlink reference (F _d0 )).

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

Subsequently, the signal digital processing unit 203 receives the downlink signal via the duplexer 201 and the received signal RF processing unit 202, synchronizes with the frequency F _dr (= F _d0 + f _d ) by the AFC function, and the uplink signal. _Is transmitted at the frequency _Fur (= _Fu0 + 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, thereby subtracting the frequency _Fus (=) of the uplink signal. F _u0 + f _d ) will be determined.

Subsequently, the radio base station 401 receives the uplink signal by the antenna 100 at a frequency _Fur (= _Fu 0 + f _d + _{fu )} further affected by the Doppler shift in the uplink signal. 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 the reference clock signal input from the timing control unit 105 so as to reduce it by the amount corresponding to the downlink and uplink transition frequencies (f _d + _fu ), and transmits the transmission signal digital processing unit. Output to 106.

Next, the transmission signal digital processing unit 106 transmits a downlink signal at a frequency F _ds (= F _d0 − ( _fu + f _d )) based on the corrected reference clock signal output by the Doppler shift correction unit 108. Send.

Subsequently, the wireless terminal 301 receives the downlink signal 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 the downlink signal at the frequency _Fur (= _Fu0 ).

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

Further, the Doppler shift correction unit 108 calculates in advance the downlink and uplink transition frequencies (f _d + _fu ) 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 representing 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 downlink and uplink transition frequencies (f _d + _fu ) according to the equations 3 and 4. However, it is assumed that the velocity c is the speed of light, the velocity v is the velocity 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 temperature is 0 degrees 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. The velocity v is the current velocity 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 position information of the wireless terminal 301 may be transmitted from the wireless terminal 301 to the wireless base station 401. Here, the location information is transmitted using, for example, the MDT (Minimization of Drive Tests) function of the wireless terminal 301. Alternatively, the position information of the wireless terminal 301 may be measured by the wireless base station 401. Alternatively, the position 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 area in the past, and from the wireless base station in the area immediately before the handover to the wireless base station 401 newly in the area. It 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 Shinkansen, the position information is calculated from the operation information. May be done. The information regarding which wireless terminal the location information is related to may be identified by, for example, the information of the terminal identifier of the radio terminal associated with the location information. The terminal identifier is, for example, IMSI (International Mobile Subscriber Identity).

Other configurations in this 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 wireless communication system according to the second embodiment of the present invention. 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 according to the desired processing.

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

Next, the Doppler shift correction unit 108 of the radio base station 401 is at a frequency F _d0 − ( _fu + f _d ) obtained by subtracting the sum (f _d + _fu ) of the uplink and downlink mutation 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 an uplink signal (frequency is _Fu0 ) (step S150).

Other operations in this embodiment are the same as the operations in the first embodiment.

As described above, in the wireless communication system 801 of the present 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. Then, the Doppler shift correction unit 108 determines the frequency of the Doppler shift for all the wireless terminals existing in the cell 601 among the plurality of wireless terminals 301, 302, ... Based on the movement speed information. Correct the change. 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 shifts the Doppler to all the wireless terminals existing in the cell 601. Corrects the change in frequency due to. Further, the wireless communication system 801 does not include a special device other than the wireless terminals 301, 302, ... And the wireless base station 401. Therefore, the wireless communication system 801 of the present embodiment has an effect that the load of the baseband processing unit related to the Doppler shift correction generated between the terminal and the terminal inside the mobile body moving at high speed can be suppressed at low cost.

Further, the radio base station 401 may further include a beamforming unit (not shown). The beamforming unit uses beamforming technology to make the position of the beam (cell 601) follow the position of the wireless terminal 301. The beamforming unit concentrates the beam of radio waves in the direction in which the wireless terminal exists by adjusting the phase of the radio waves radiated by using, for example, the phased array antenna of Patent Document 3 as the antenna 100. When the radio base station 401 includes a beamforming unit, it is easy to compensate for the Doppler shift even when a plurality of high-speed moving bodies 501 and 502 having different moving speeds or different moving directions are present close to each other. There is an effect. Further, when the radio base station 401 includes a beamforming unit, there is an effect that different cells can be set for different positions (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 a radio base station according to 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 the operation programs of the CPU 903 such as the Doppler shift correction unit 108, the Doppler shift correction unit 158, and the movement 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 a program 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 radio base station 907 may have a device configuration for connecting a keyboard 904 and a monitor 905, if necessary.

The radio base station in each embodiment of the present invention described above may be realized by a dedicated device, but a computer (information processing device) other than the operation of the hardware in which the I / O device 908 executes communication with the outside. ) Is also feasible. 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 into the CPU 903, and executes the read software program in the CPU 903. In the case of each of the above-described embodiments, the software program may be described so as to be able to realize the functions of each part of the radio base station shown in FIGS. 1 and 6 as described above. However, it is assumed that each of these parts includes hardware as appropriate. Then, in such a case, the software program (computer program) can be regarded as constituting the present invention. Further, a computer-readable storage medium containing the software program can be regarded as constituting the present invention.

The present invention has been exemplified above by way of each of the above-described embodiments and modifications thereof. However, the technical scope of the present invention is not limited to the scope described in each of the above-described embodiments and modifications thereof. It will be apparent to those skilled in the art that various changes or improvements can be made to such embodiments. In such cases, new embodiments with such modifications or improvements may also be included in the technical scope of the invention. And this is clear from the matters stated in the claims.

Some or all of the above embodiments may also be described, but not limited to:
(Appendix 1)
With the terminal antenna
Includes a terminal-side wireless communication means 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.
With multiple wireless terminals that may be moved by a high speed mobile
Base station side antenna and
The downlink signal is transmitted via the base station side antenna 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. The base station side wireless communication means for receiving the uplink signal at the base station side reception frequency, which is equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna, is included.
The radio base station included in a radio communication system including a radio base station having a cell including a part of a movement path of the high-speed mobile body.
Further provided with a moving speed calculation means for generating moving speed information indicating the 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.
When the certain terminal is present in the certain cell, the base station side wireless communication means is used for all the terminals existing in the certain cell among the plurality of wireless terminals based on the movement speed information. On the other hand, the downlink reference frequency of the downlink is uniformly subtracted from the frequency of the downlink whose downlink reference frequency has changed due to the Doppler shift accompanying the movement of the terminal with respect to the base station side antenna, and the downlink frequency. The uplink reference frequency of the uplink is subtracted from the frequency of the uplink whose uplink reference frequency has changed due to the Doppler shift, and the uplink frequency is calculated. Based on the calculated downlink frequency and the uplink frequency, the uplink frequency is calculated. A radio base station equipped with a Doppler shift correction means for correcting a frequency change due to a 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.
When the terminal is present in the cell, the Doppler shift correction means subtracts the sum of the downlink frequency and the uplink frequency from the downlink reference frequency in the cell to perform the base. The radio base station according to Appendix 1, which determines the transmission frequency on the station side.
(Appendix 3)
The Doppler shift correction means, when the terminal is present in the cell, in the 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 Appendix 1, wherein the uplink signal received from each of the terminals is corrected as a signal in which the uplink reference frequency is changed by the uplink transition frequency.
(Appendix 4)
The moving speed calculating means generates the moving speed information based on a plurality of sets of information on the position where the certain terminal was present and information on the time when the certain terminal was present at the position. The radio base station according to any one of the above items.
(Appendix 5)
The radio base station according to any one of Supplementary note 1 to 4, wherein the moving speed calculating means generates the moving speed information based on the operation information of the high-speed moving body.
(Appendix 6)
The cell is described in any one of Appendix 1 to 5, wherein all the terminals existing in the cell among the wireless terminals are set to be moved by the high-speed mobile body. Radio base station.
(Appendix 7)
The radio base station according to any one of Appendix 1 to 6, further comprising a beamforming means for making the position of the cell follow the movement of the terminal.
(Appendix 8)
With the terminal antenna
Includes a terminal-side wireless communication means 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.
With multiple wireless terminals that may be moved by a high speed mobile
Base station side antenna and
The downlink signal is transmitted via the base station side antenna 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. The base station side wireless communication means for receiving the uplink signal at the base station side reception frequency, which is equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna, is included.
A radio communication system including a radio base station having a cell including a part of the movement path of the high-speed mobile body.
The radio base station further includes a movement speed calculation means for generating movement speed information indicating the movement speed and direction of a terminal among the plurality of radio terminals with respect to the base station side antenna at the present time.
When the certain terminal is present in the certain cell, the base station side wireless communication means is used for all the terminals existing in the certain cell among the plurality of wireless terminals based on the movement speed information. On the other hand, the downlink reference frequency of the downlink is uniformly subtracted from the frequency of the downlink whose downlink reference frequency has changed due to the Doppler shift accompanying the movement of the terminal with respect to the base station side antenna, and the downlink frequency. The uplink reference frequency of the uplink is subtracted from the frequency of the uplink whose uplink reference frequency has changed due to the Doppler shift, and the uplink frequency is calculated. Based on the calculated downlink frequency and the uplink frequency, the uplink frequency is calculated. A wireless communication system provided with a Doppler shift correction means for correcting a frequency change due to a Doppler shift.
(Appendix 9)
With the terminal antenna
Includes a terminal-side wireless communication means 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.
With multiple wireless terminals that may be moved by a high speed mobile
Base station side antenna and
The downlink signal is transmitted via the base station side antenna 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. The base station side wireless communication means for receiving the uplink signal at the base station side reception frequency, which is equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna, is included.
A method for controlling a radio base station, which is included in a radio communication system including a radio base station having a cell including a part of a movement path of the high-speed mobile body.
The radio base station generates moving speed information indicating the moving speed and direction of a terminal among the plurality of wireless terminals with respect to the base station side antenna at the present time.
When the certain terminal exists in the certain cell by the base station side wireless communication means, all the terminals existing in the certain cell among the plurality of wireless terminals are used based on the movement speed information. On the other hand, the downlink reference frequency of the downlink is uniformly subtracted from the frequency of the downlink whose downlink reference frequency has changed due to the Doppler shift accompanying the movement of the terminal with respect to the base station side antenna, and the downlink frequency. The uplink reference frequency of the uplink is subtracted from the frequency of the uplink whose uplink reference frequency has changed due to the Doppler shift, and the uplink frequency is calculated. Based on the calculated downlink frequency and the uplink frequency, the uplink frequency is calculated. A control method that corrects frequency changes due to Doppler shift.
(Appendix 10)
With the terminal antenna
Includes a terminal-side wireless communication means 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.
With multiple wireless terminals that may be moved by a high speed mobile
Base station side antenna and
The downlink signal is transmitted via the base station side antenna 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. The base station side wireless communication means for receiving the uplink signal at the base station side reception frequency, which is equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna, is included.
A computer included in a radio communication system including a radio base station having a cell including a part of a movement path of the high-speed mobile body.
At present, a moving speed calculation process for generating moving speed information indicating the moving speed and direction of a certain terminal among the plurality of wireless terminals with respect to the base station side antenna, and
When the certain terminal exists in the certain cell by the base station side wireless communication means, all the terminals existing in the certain cell among the plurality of wireless terminals are used based on the movement speed information. On the other hand, the downlink reference frequency of the downlink is uniformly subtracted from the frequency of the downlink whose downlink reference frequency has changed due to the Doppler shift accompanying the movement of the terminal with respect to the base station side antenna, and the downlink frequency. The uplink reference frequency of the uplink is subtracted from the frequency of the uplink whose uplink reference frequency has changed due to the Doppler shift, and the uplink frequency is calculated. Based on the calculated downlink frequency and the uplink frequency, the uplink frequency is calculated. A control program that executes Doppler shift correction processing that corrects frequency changes due to Doppler shift.
(Appendix 11)
The base station-side wireless communication means has a portion of the frequency change due to the Doppler shift that cannot be uniformly corrected by the Doppler shift correction means in the cell of the plurality of wireless terminals. The radio base station according to any one of Appendix 1 to 7, which is individually corrected for each terminal.
(Appendix 12)
The cell is any one of Appendix 1 to 7, wherein the direction of the terminal with respect to the base station side antenna is set to be approximately constant while the terminal passes through the cell. Item or the 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 frequency or the uplink frequency, and doubles either the calculated downlink frequency or the uplink frequency to calculate the sum. 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.
When the terminal is present in the cell, the Doppler shift correction means subtracts the sum of the downlink frequency and the uplink frequency from the downlink reference frequency in the cell to perform the base. The wireless communication system according to Appendix 8 for determining a station-side transmission frequency.
(Appendix 15)
The terminal-side wireless communication means calculates the terminal-side transmission frequency by subtracting a predetermined frequency difference from the terminal-side reception frequency.
When the terminal is present in the cell by the base station side wireless communication means, the sum of the downlink frequency and the uplink frequency is subtracted from the downlink reference frequency in the cell. The control method according to Appendix 9, which determines the transmission frequency on the base station side.
(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 process performs the base by subtracting the sum of the downlink frequency and the uplink frequency from the downlink reference frequency in the cell when the terminal is present in the cell. The control program according to Appendix 10 for determining the station-side transmission frequency.

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

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

Claims (10)

With the terminal antenna
Includes a terminal-side wireless communication means 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.
With multiple wireless terminals that may be moved by a high speed mobile
Base station side antenna and
The downlink signal is transmitted via the base station side antenna 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. The base station side wireless communication means for receiving the uplink signal at the base station side reception frequency, which is equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna, is included.
The radio base station included in a radio communication system including a radio base station having a cell including a part of a movement path of the high-speed mobile body.
Further provided with a moving speed calculation means for generating moving speed information indicating the 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.
When the certain terminal is present in the certain cell, the base station side wireless communication means is used for all the terminals existing in the certain cell among the plurality of wireless terminals based on the movement speed information. On the other hand, the downlink reference frequency of the downlink is uniformly subtracted from the frequency of the downlink whose downlink reference frequency has changed due to the Doppler shift accompanying the movement of the terminal with respect to the base station side antenna, and the downlink frequency. The uplink reference frequency of the uplink is subtracted from the frequency of the uplink whose uplink reference frequency has changed due to the Doppler shift, and the uplink frequency is calculated. Based on the calculated downlink frequency and the uplink frequency, the uplink frequency is calculated. A radio base station equipped with a Doppler shift correction means for correcting a frequency change due to a 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.
When the terminal is present in the cell, the Doppler shift correction means subtracts the sum of the downlink frequency and the uplink frequency from the downlink reference frequency in the cell to perform the base. The radio base station according to claim 1, wherein the transmission frequency on the station side is determined. The Doppler shift correction means, when the terminal is present in the cell, in the 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 the all terminals is corrected as a signal in which the uplink reference frequency is changed by the uplink transition frequency. The moving speed calculation means generates the moving speed information based on a plurality of sets of information on the position where the certain terminal exists and information on the time when the certain terminal existed at the position. The radio base station according to any one of 3. The radio base station according to any one of claims 1 to 4, wherein the moving speed calculating means generates the moving speed information based on the operation information of the high-speed moving body. The cell is according to any one of claims 1 to 5, wherein all the terminals existing in the cell among the wireless terminals are set to be moved by the high-speed mobile body. The radio base station described. The radio base station according to any one of claims 1 to 6, further comprising a beamforming means for making the position of the cell follow the movement of the terminal. With the terminal antenna
Includes a terminal-side wireless communication means 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.
With multiple wireless terminals that may be moved by a high speed mobile
Base station side antenna and
The downlink signal is transmitted via the base station side antenna 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. The base station side wireless communication means for receiving the uplink signal at the base station side reception frequency, which is equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna, is included.
A radio communication system including a radio base station having a cell including a part of the movement path of the high-speed mobile body.
The radio base station further includes a movement speed calculation means for generating movement speed information indicating the movement speed and direction of a terminal among the plurality of radio terminals with respect to the base station side antenna at the present time.
When the certain terminal is present in the certain cell, the base station side wireless communication means is used for all the terminals existing in the certain cell among the plurality of wireless terminals based on the movement speed information. On the other hand, the downlink reference frequency of the downlink is uniformly subtracted from the frequency of the downlink whose downlink reference frequency has changed due to the Doppler shift accompanying the movement of the terminal with respect to the base station side antenna, and the downlink frequency. The uplink reference frequency of the uplink is subtracted from the frequency of the uplink whose uplink reference frequency has changed due to the Doppler shift, and the uplink frequency is calculated. Based on the calculated downlink frequency and the uplink frequency, the uplink frequency is calculated. A wireless communication system provided with a Doppler shift correction means for correcting a frequency change due to a Doppler shift. With the terminal antenna
Includes a terminal-side wireless communication means 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.
With multiple wireless terminals that may be moved by a high speed mobile
Base station side antenna and
The downlink signal is transmitted via the base station side antenna 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. The base station side wireless communication means for receiving the uplink signal at the base station side reception frequency, which is equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna, is included.
A method for controlling a radio base station, which is included in a radio communication system including a radio base station having a cell including a part of a movement path of the high-speed mobile body.
The radio base station generates moving speed information indicating the moving speed and direction of a terminal among the plurality of wireless terminals with respect to the base station side antenna at the present time.
When the certain terminal exists in the certain cell by the base station side wireless communication means, all the terminals existing in the certain cell among the plurality of wireless terminals are used based on the movement speed information. On the other hand, the downlink reference frequency of the downlink is uniformly subtracted from the frequency of the downlink whose downlink reference frequency has changed due to the Doppler shift accompanying the movement of the terminal with respect to the base station side antenna, and the downlink frequency. The uplink reference frequency of the uplink is subtracted from the frequency of the uplink whose uplink reference frequency has changed due to the Doppler shift, and the uplink frequency is calculated. Based on the calculated downlink frequency and the uplink frequency, the uplink frequency is calculated. A control method that corrects frequency changes due to Doppler shift. With the terminal antenna
Includes a terminal-side wireless communication means 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.
With multiple wireless terminals that may be moved by a high speed mobile
Base station side antenna and
The downlink signal is transmitted via the base station side antenna 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. The base station side wireless communication means for receiving the uplink signal at the base station side reception frequency, which is equal to the terminal side transmission frequency when the terminal side antenna is stationary with respect to the base station side antenna, is included.
A computer included in a radio communication system including a radio base station having a cell including a part of a movement path of the high-speed mobile body.
At present, a moving speed calculation process for generating moving speed information indicating the moving speed and direction of a certain terminal among the plurality of wireless terminals with respect to the base station side antenna, and
When the certain terminal exists in the certain cell by the base station side wireless communication means, all the terminals existing in the certain cell among the plurality of wireless terminals are used based on the movement speed information. On the other hand, the downlink reference frequency of the downlink is uniformly subtracted from the frequency of the downlink whose downlink reference frequency has changed due to the Doppler shift accompanying the movement of the terminal with respect to the base station side antenna, and the downlink frequency. The uplink reference frequency of the uplink is subtracted from the frequency of the uplink whose uplink reference frequency has changed due to the Doppler shift, and the uplink frequency is calculated. Based on the calculated downlink frequency and the uplink frequency, the uplink frequency is calculated. A control program that executes Doppler shift correction processing that corrects frequency changes due to Doppler shift.

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