JP2022036483A - Phase calculation device, terminal, communication system, phase calculation method, and phase calculation program - Google Patents

Abstract

To correctly calculate a phase difference corresponding to Doppler shift without increasing the ratio of a pilot signal in a transmission signal even when the Doppler shift is large in wireless communication.SOLUTION: A phase calculation device includes moving direction calculation means that calculates the moving direction on the basis of information that represents a first position where a terminal is located, information that represents a second position where the terminal is located after the terminal has been moved, and information that represents a third position where a base station that performs wireless communication with the terminal is located, and Doppler shift calculation means that calculates a phase difference in a received carrier corresponding to the Doppler shift caused by the movement when the carrier is received on the basis of the calculated direction, information that represents the speed of the terminal at the time of the movement, information that represents the frequency of the carrier used for wireless communication, and information that represents a repetition period of a pilot signal modulated on the carrier. The size of a range of possible values of the number of rotations representing the phase difference is larger than one rotation.SELECTED DRAWING: Figure 16

Description

The present invention relates to a technique for compensating for Doppler shift associated with high-speed movement of a terminal in wireless communication.

In order to demodulate data symbols with high accuracy in mobile wireless communication, it is important to realize highly accurate channel estimation. Especially in a high-speed moving environment such as a Shinkansen or a linear motor car, the channel estimation accuracy may be significantly deteriorated due to the Doppler shift.

Therefore, in channel interpolation, the Doppler shift amount may be estimated by automatic frequency control (AFC) using a pilot symbol.

An example of an automatic frequency control technique for compensating for Doppler shift is disclosed in Patent Document 1. The mobile wireless communication system described in Patent Document 1 includes a base station and a mobile station. The base station has its own station position information storage unit that stores the position information of the base station. The base station transmits transmission data including the position information of the base station to the mobile station. The mobile station includes a Doppler effect calculator and an internal oscillator. The Doppler effect calculation unit calculates the frequency error due to the Doppler effect of the transmission data based on the position information, velocity information, and movement direction information of the mobile station acquired by itself and the position information of the base station included in the transmission data. do. The internal oscillator oscillates a frequency signal corrected for frequency error due to the Doppler effect of the frequency of the transmitted data. As a result of the above-mentioned configuration, in the mobile wireless communication system described in Patent Document 1, the mobile station performs frequency tracking corrected for the frequency error of the transmission data due to the Doppler effect.

Further, an example of a technique for compensating for Doppler shift is disclosed in Patent Document 2. The multi-carrier receiving device described in Patent Document 2 calculates the channel characteristics of the data symbol position as the primary channel estimation value based on the channel characteristics estimated by the pilot symbol reception signal for a plurality of subcarriers. Then, the multi-carrier receiving device channel-compensates and decodes each data symbol reception signal based on the primary channel estimated value. Then, the multi-carrier receiving device weights and adds the channel re-estimated value at each symbol position estimated by the decoded signal, and calculates the channel characteristic at the predetermined symbol position as the secondary channel estimated value. As a result of the above configuration, the multicarrier receiver described in Patent Document 2 obtains channel estimates even in an environment where frequency selective fading is present and dynamic fading subject to Doppler frequency fluctuations is present.

Japanese Unexamined Patent Publication No. 2014-160891 Japanese Unexamined Patent Publication No. 2004-36494

Generally, the faster the moving speed of the terminal, the larger the amount of phase rotation due to the Doppler effect. Therefore, when the amount of phase rotation due to the Doppler effect exceeds a certain value (for example, 2π) in a high-speed moving environment, it becomes difficult to correctly estimate the phase. For example, the techniques described in Patent Documents 1 and 2 do not disclose a method for correctly estimating the phase when the amount of rotation of the phase due to the Doppler effect is large. In such a case, there is a problem that the channel estimation accuracy in automatic frequency control is significantly deteriorated.

As a method for solving the problem that the channel estimation accuracy is deteriorated, it is generally considered to shorten the insertion interval of the pilot symbol (see, for example, the description in paragraph [0059] of Patent Document 2). However, if the insertion interval of the pilot symbol is shortened, the ratio of the pilot symbol in the transmission data becomes large, and as a result, there is a problem that the transmission efficiency is lowered.

The present invention has been made in view of the above problems, and even when the Doppler shift is large in wireless communication, the phase difference corresponding to the Doppler shift can be obtained without increasing the ratio of the pilot signal in the transmission signal. The main purpose is to calculate correctly.

In one aspect of the present invention, the phase calculation device includes information indicating the first position where the terminal was present, information indicating the second position where the terminal was present after the movement of the terminal, and a base station that wirelessly communicates with the terminal. The movement direction calculation means for calculating the movement direction based on the information indicating the third position, the calculated direction, the information indicating the speed of the terminal at the time of movement, and the frequency of the carrier used for wireless communication. Doppler shift to calculate the phase difference in the received carrier, corresponding to the Doppler shift due to movement when the carrier is received, based on the information represented and the information representing the repetition period of the pilot signal modulated over the carrier. Includes calculation means. The size of the range of possible values of the rotation speed representing the phase difference is larger than one rotation.

In one aspect of the invention, the terminal includes a phase calculator and data signal demodulation means. The phase calculator has information representing the first position where the terminal was present, information representing the second position where the terminal was present after the movement of the terminal, and information representing the third position where the base station that performs wireless communication with the terminal is present. Based on the movement direction calculation means for calculating the movement direction, the calculated direction, the information indicating the speed of the terminal at the time of movement, the information indicating the frequency of the carrier used for wireless communication, and the carrier. It includes a Doppler shift calculation means for calculating the phase difference in the received carrier corresponding to the Doppler shift due to the movement when the carrier is received, based on the information representing the repetition period of the pilot signal modulated by. The size of the range of possible values of the rotation speed representing the phase difference is larger than one rotation. The terminal includes a channel estimation means, a channel interpolation means, and a data signal demodulation means. The channel estimation means estimates the channel of the pilot signal received from the base station. The channel interpolation means estimates the channel of the data signal received from the base station based on the calculation result of the phase difference calculated by the phase calculator and the estimation result of the channel of the pilot signal estimated by the channel estimation means. .. The data signal demodulation means demodulates the data signal based on the estimation result of the channel of the data signal estimated by the channel interpolation means.

In one aspect of the invention, the communication system includes a terminal and a base station. The terminal includes a phase calculator and data signal demodulation means. The phase calculator has information representing the first position where the terminal was present, information representing the second position where the terminal was present after the movement of the terminal, and information representing the third position where the base station that performs wireless communication with the terminal is present. Based on the movement direction calculation means for calculating the movement direction, the calculated direction, the information indicating the speed of the terminal at the time of movement, the information indicating the frequency of the carrier used for wireless communication, and the carrier. It includes a Doppler shift calculation means for calculating the phase difference in the received carrier corresponding to the Doppler shift due to the movement when the carrier is received, based on the information representing the repetition period of the pilot signal modulated by. The size of the range of possible values of the rotation speed representing the phase difference is larger than one rotation. The terminal includes a channel estimation means, a channel interpolation means, and a data signal demodulation means. The channel estimation means estimates the channel of the pilot signal received from the base station. The channel interpolation means estimates the channel of the data signal received from the base station based on the calculation result of the phase difference calculated by the phase calculator and the estimation result of the channel of the pilot signal estimated by the channel estimation means. .. The data signal demodulation means demodulates the data signal based on the estimation result of the channel of the data signal estimated by the channel interpolation means. The base station transmits a pilot signal and a data signal.

In one aspect of the present invention, the phase calculation method includes information indicating the first position where the terminal was present, information indicating the second position where the terminal was present after the movement of the terminal, and a base station that wirelessly communicates with the terminal. Based on the information representing the third position to be moved, the direction of movement is calculated, the calculated direction, the information indicating the speed of the terminal at the time of movement, the information indicating the frequency of the carrier used for wireless communication, and the carrier. Based on the information representing the repetition period of the pilot signal modulated above, the phase difference in the received carrier corresponding to the Doppler shift due to the movement when the carrier is received is calculated. The size of the range of possible values of the rotation speed representing the phase difference is larger than one rotation.

In one aspect of the present invention, the phase calculation program includes information indicating the first position where the terminal was present, information indicating the second position where the terminal was present after the movement of the terminal, and the terminal in the computer provided in the phase calculation device. Movement direction calculation processing that calculates the direction of movement based on the information that indicates the third position where the base station that performs wireless communication exists, information that indicates the calculated direction, the speed of the terminal at the time of movement, wireless communication The received carrier corresponding to the Doppler shift due to the movement when the carrier is received, based on the information representing the carrier frequency used in the carrier and the information representing the repetition period of the pilot signal modulated on the carrier. The Doppler shift calculation process for calculating the phase difference in is executed. The size of the range of possible values of the rotation speed representing the phase difference is larger than one rotation.

According to the present invention, even when the Doppler shift is large in wireless communication, there is an effect that the phase difference corresponding to the Doppler shift can be correctly calculated without increasing the ratio of the pilot signal in the transmission signal.

It is a block which shows an example of the structure of the communication system in 1st Embodiment of this invention. It is a block diagram which shows an example of the structure of the base station in 1st Embodiment of this invention. It is a block diagram which shows an example of the structure of the transmission side wireless communication part in 1st Embodiment of this invention. It is a block diagram which shows an example of the structure of the terminal in 1st Embodiment of this invention. It is a block diagram which shows an example of the structure of the receiving side wireless communication part in 1st Embodiment of this invention. It is a block diagram which shows an example of the structure of the phase calculation part in 1st Embodiment of this invention. It is a flowchart which shows the operation of the phase calculation part in 1st Embodiment of this invention. It is a flowchart which shows the operation of the phase calculation part in 1st Embodiment of this invention. It is a flowchart which shows the operation of the terminal in 1st Embodiment of this invention. It is a schematic diagram which shows an example of the resource block in 1st Embodiment of this invention. It is a block diagram which shows an example of the structure of the communication system in 1st Embodiment of this invention. It is a block diagram which shows an example of the structure of the terminal in 2nd Embodiment of this invention. It is a block diagram which shows an example of the structure of the base station in 2nd Embodiment of this invention. It is a block diagram which shows an example of the structure of the phase calculation apparatus in 3rd Embodiment of this invention. It is a block diagram which shows an example of the structure of the communication system which is the operating environment of the phase calculation apparatus in 4th Embodiment of this invention. It is a block diagram which shows an example of the structure of the phase calculation apparatus in 4th Embodiment of this invention. It is a flowchart which shows the operation of the phase calculation apparatus in 4th Embodiment of this invention. It is a block diagram which shows an example of the hardware composition which can realize the phase calculation apparatus 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, the same components are designated by the same reference numerals, and the description thereof will be omitted as appropriate.
(First Embodiment)
The first embodiment of the present invention will be described.

The configuration in this embodiment will be described.

FIG. 1 is a block diagram showing an example of a configuration of a communication system according to the first embodiment of the present invention. As shown in FIG. 1, the communication system 100 of the present embodiment includes a base station 200 and a terminal 300. Hereinafter, the downlink signal (downlink) from the base station 200 to the terminal 300 will be described, and the uplink signal (uplink) from the terminal 300 to the base station 200 will be omitted. The base station 200 and the terminal 300 are connected by wireless communication.

FIG. 2 is a block diagram showing an example of the configuration of the base station 200 according to the first embodiment of the present invention. As shown in FIG. 2, the base station 200 includes a channel control unit 210 and a transmitting side wireless communication unit 220.

In order to estimate the channel, the channel control unit 210 discretely arranges a pilot symbol (an example of a pilot signal), which is a known pattern, with respect to the resource block according to a predetermined setting. Further, the channel control unit 210 inputs data to be transmitted and arranges a data symbol (an example of a data signal) in the resource block. The channel control unit 210 outputs a resource block (transmission data) including a data symbol, a pilot symbol, and the like to the transmission side wireless communication unit 220. The data symbol is a symbol obtained by modulating data to be transmitted (bit string, audio data, video data, etc.). The data to be transmitted is supplied, for example, by a process that relays data from a server or another terminal.

FIG. 3 is a block diagram showing an example of the configuration of the transmitting side wireless communication unit 220 according to the first embodiment of the present invention. As shown in FIG. 3, the transmitting side wireless communication unit 220 includes a D / A converter 510 (Digital to Analog converter), a carrier wave oscillator 520, a multiplier 530, an amplifier 540, an antenna 550, and the like. The transmitting side wireless communication unit 220 transmits transmission data including a data symbol (an example of a data signal) and a pilot symbol input from the channel control unit 210 to the receiving side wireless communication unit 310 (described later) via radio waves. .. The transmission side wireless communication unit 220 is a general transmission circuit that wirelessly transmits data symbols, pilot symbols, and the like. Therefore, further detailed description of the configuration of the transmitting side wireless communication unit 220 will be omitted.

FIG. 4 is a block diagram showing an example of the configuration of the terminal 300 according to the first embodiment of the present invention. As shown in FIG. 4, the terminal 300 includes a receiving side wireless communication unit 310, a channel estimation unit 320, a phase calculation unit 400, a channel interpolation unit 330, and a data symbol demodulation unit 340.

FIG. 5 is a block diagram showing an example of the configuration of the receiving side wireless communication unit 310 according to the first embodiment of the present invention. As shown in FIG. 5, the receiving side wireless communication unit 310 includes an A / D converter 610 (Analog to Digital converter), a carrier wave oscillator 620, a multiplier 630, an amplifier 640, an antenna 650, and the like. The receiving-side wireless communication unit 310 receives data symbols, pilot symbols, and the like from the transmitting-side wireless communication unit 220 via radio waves. The receiving side wireless communication unit 310 has an automatic frequency control function, and is a general receiving circuit that outputs wirelessly received data symbols, pilot symbols, and the like. Therefore, further detailed description of the configuration of the receiving side wireless communication unit 310 will be omitted. The receiving side wireless communication unit 310 outputs received data including data symbols, pilot symbols, etc. to the data symbol demodulation unit 340 and the channel estimation unit 320.

The channel estimation unit 320 inputs a pilot symbol from the receiving side wireless communication unit 310, and outputs the channel estimation value of the input pilot symbol to the channel interpolation unit 330.

The phase calculation unit 400 holds information regarding the positions (for example, latitude, longitude, and altitude) of the terminal 300 and the base station 200. Then, the phase calculation unit 400 calculates the phase of the received pilot symbol, which changes due to the Doppler shift as the terminal 300 moves, based on the information regarding the positions of the holding terminal 300 and the base station 200. do. Then, the phase calculation unit 400 outputs the calculated phase to the channel interpolation unit 330. Here, the phase calculation unit 400 may acquire information regarding the positions of the terminal 300 and the base station 200 from the sensor or may be acquired via the network, if necessary.

The channel interpolation unit 330 interpolates the channel estimation value of the data symbol based on the channel estimation value of the pilot symbol input from the channel estimation unit 320 and the phase of the pilot symbol input from the phase calculation unit 400. The channel interpolation unit 330 outputs the interpolated channel to the data symbol demodulation unit 340.

The data symbol demodulation unit 340 demodulates the source symbol based on the data symbol input from the receiving side wireless communication unit 310 and the interpolated channel input from the channel interpolation unit 330. Specifically, the data symbol demodulation unit 340 demodulates the source symbol by dividing the received data symbol by the channel estimation value to remove the influence of the transmission line. Then, the data symbol demodulation unit 340 outputs the data of the transmission source. The source data is processed, for example, by a process in the application program.

FIG. 6 is a block diagram showing an example of the configuration of the phase calculation unit 400 according to the first embodiment of the present invention. As shown in FIG. 6, the phase calculation unit 400 includes a parameter acquisition unit 410, a position information acquisition unit 420, a position information storage unit 430, a movement direction calculation unit 440, a speed information acquisition unit 450, and a Doppler shift calculation. Includes part 460.

The parameter acquisition unit 410 acquires the carrier frequency and the position information of the base station 200. The parameter acquisition unit 410 outputs the acquired carrier frequency to the Doppler shift calculation unit 460, and outputs the acquired position information of the base station 200 to the movement direction calculation unit 440. The parameter acquisition unit 410 acquires, for example, the carrier frequency and the position information of the base station 200 from the broadcast information obtained when the terminal 300 starts the connection in the communication area. The position information of the base station 200 may be acquired by using a positioning system such as GPS (Global Positioning System), or may be used as information (latitude and longitude, address, etc.) regarding the place where the base station 200 is installed. It may be obtained based on.

The position information acquisition unit 420 acquires the position information of the terminal 300. The position information acquisition unit 420 outputs the acquired position information to the movement direction calculation unit 440 and the position information storage unit 430. The position information may be acquired from, for example, a system that manages the position of the terminal 300 (for example, a positioning system using GPS, base station positioning, or the like), or is based on the identification number of the communication area to which the terminal 300 belongs. May be obtained. Alternatively, the position information may be calculated using an acceleration sensor, a speed sensor, or the like included in the terminal 300.

The position information storage unit 430 stores the past position information of the terminal 300. The position information storage unit 430 outputs the stored position information to the movement direction calculation unit 440.

The movement direction calculation unit 440 calculates the movement direction of the terminal 300. The movement direction calculation unit 440 outputs the calculated movement direction to the Doppler shift calculation unit 460.

The speed information acquisition unit 450 acquires the moving speed (moving speed) of the terminal 300. The speed information acquisition unit 450 outputs the acquired movement speed to the Doppler shift calculation unit 460. The moving speed may be acquired from, for example, an acceleration sensor or a speed sensor of the terminal 300. Alternatively, the moving speed may be acquired from a system that manages the position of the terminal 300 (for example, a positioning system using GPS, base station positioning, or the like).

The Doppler shift calculation unit 460 calculates the Doppler shift. The Doppler shift calculation unit 460 outputs the calculated Doppler shift to the channel interpolation unit 330.

The operation in this embodiment will be described.

7 and 8 are flowcharts showing the operation of the phase calculation unit 400 according to the first embodiment of the present invention.

First, the parameter acquisition unit 410 acquires the position information (position O) of the base station 200 and outputs the acquired position information to the movement direction calculation unit 440 (step S110).

Next, the position information acquisition unit 420 acquires the current position information (position P) of the terminal 300 and outputs the acquired position information to the movement direction calculation unit 440 (step S120).

Next, the position information storage unit 430 acquires the position information (position P') of the past terminal 300, and outputs the acquired position information to the movement direction calculation unit 440 (step S130). Here, the processing order of steps S110 to S130 may be arbitrary.

Next, the moving direction calculation unit 440 calculates the moving direction θ _m of the terminal 300 using, for example, the equation (1) (step S140). Here, the moving direction θ _m is an angle P'OP.

Here, OP is the distance between the position O and the position P, OP'is the distance between the position O and the position P', and PP'is the distance between the position P and the position P'. Further, the moving direction θ _m may be expressed by, for example, the arc degree method (unit: radian), the frequency method (unit: degree), or the rotation speed (unit: rotation). You may. In the following, a case where the moving direction θ _m is expressed by the arc degree method and takes a value of 0 (radian) or more and less than π (radian) will be described as an example.

Next, the movement direction calculation unit 440 outputs the calculated movement direction of the terminal 300 to the Doppler shift calculation unit 460 (step S150).

Next, the position information acquisition unit 420 saves the current position information of the terminal 300 in the position information storage unit 430 (step S160). The initial value of the current position information of the terminal 300 stored in the position information storage unit 430 is the position information of the terminal 300 obtained at the start of communication of the terminal 300, the coordinates of the terminal 300 manually set by a person, and the like. You may. The processing order of steps S150 to S160 may be arbitrary.

Next, the parameter acquisition unit 410 acquires carrier frequency information (carrier frequency _fc ) and outputs the acquired carrier frequency information to the Doppler shift calculation unit 460 (step S210).

Next, the speed information acquisition unit 450 acquires the current speed information (speed v) of the terminal 300, and outputs the acquired speed information to the Doppler shift calculation unit 460 (step S220). Here, the processing order of steps S210 to S220 may be arbitrary.

Next, the Doppler shift calculation unit 460 calculates the phase difference θ _d (hereinafter, also simply referred to as “Doppler shift”) corresponding to the Doppler shift using the equation (2) (step S230).

Here, c is the speed of light, v is the speed of movement of the terminal, and _Ts is the calculation cycle of the movement direction or the speed of movement of the terminal (hereinafter, it is assumed to be a predetermined constant). Is. Further, the Doppler shift θ _d may be expressed by, for example, the radian method, the frequency method, or the rotation speed. In the following, a case where the Doppler shift θ _d is expressed by the radian method will be described as an example. Further, the Doppler shift θ _d is set to take a value of 0 (radian) or more, for example, and can take a value of 2π (radian) or more, for example.

Next, the Doppler shift calculation unit 460 outputs the calculated information representing the Doppler shift to the channel interpolation unit 330 (step S240).

FIG. 9 is a flowchart showing the operation of the terminal 300 according to the first embodiment of the present invention.

First, the channel estimation unit 320 calculates the channel estimation value θ _p of the pilot symbol based on the received pilot symbol and outputs it to the channel interpolation unit 330 (step S310). Here, it is assumed that the channel estimated value θ _p is 0 (radian) or more and less than 2π (radian). In this embodiment, only the phase is focused on as the channel estimation value.

Next, the channel estimation unit 320 calculates the true channel estimation value _θ'p of the pilot symbol using the equation (3), for example (step S320).

Here, [] represents rounding down to the nearest whole number. A true channel estimate is obtained by adding the integer part of the phase rotation speed in the second term in addition to the channel estimate in the first term. Here, the true channel estimated value _θ'p can take a value of 0 (radian) or more, for example, a value of 2π (radian) or more.

Next, the channel interpolation unit 330 interpolates the channel estimation value of the data symbol (step S330). The channel interpolation unit 330 calculates, for example, the channel estimation values θ'p _{, n} of N data symbols between the estimated values θ _p and θ _{p + 1} of the pilot symbols by using the equation (4).

At this time, the interpolation of the channel estimation value of the data symbol may be performed by using another method.

The data symbol demodulation unit 340 demodulates the source symbol based on the data symbol obtained via the receiving side wireless communication unit 310 and the channel estimation value interpolated by the channel interpolation unit 330 (step S340). ..

FIG. 10 is a schematic diagram showing an example of a resource block according to the first embodiment of the present invention. In FIG. 10, for simplification, symbols are arranged only in the time direction of the resource blocks. As shown in FIG. 10, the channel estimated values θ'p _{and n} shown in the equation (4) are interpolated corresponding to each received data symbol.

As described above, in the communication system 100 of the present embodiment, the movement direction calculation unit 440 calculates the movement direction of the terminal 300 by using the position information of the base station 200 and the position information of the terminal 300. Then, the Doppler shift calculation unit 460 calculates the Doppler shift θ _d using the movement direction and the movement speed of the terminal 300. Here, the range of the estimated value θ _p of the pilot symbol in the channel estimation obtained by a general method is 0 ≦ θ _p <2π. Therefore, when the Doppler shift θ _d is large, if the calculated Doppler shift is used as it is for interpolation of channel estimation, the interpolation accuracy may deteriorate. However, as shown in the equation (3), the channel estimation unit 320 calculates the true channel estimation value _θ'p even when the Doppler shift θ _d is 2π or more. Then, the channel interpolation unit 330 calculates the channel estimation value θ'p _{, n} of the data symbol by using the true channel estimation value _θ'p . Then, the data symbol demodulation unit 340 demodulates the source symbol using the channel estimated values θ'p _{, n} of the data symbol.

Further, in the communication system 100 of the present embodiment, even when the Doppler shift θ _d can be 2π or more, it is not necessary to shorten the repetition period of the pilot symbol in order to suppress the deterioration of the channel estimation accuracy. That is, since the ratio of the pilot symbol in the transmission data does not increase, the transmission efficiency does not decrease.

Therefore, in the communication system 100 of the present embodiment, even when the Doppler shift is large in wireless communication, the phase difference corresponding to the Doppler shift can be correctly calculated without increasing the ratio of the pilot signal in the transmission signal. There is an effect.

Further, in the communication system 100 of the present embodiment, as shown in the equation (3), the Doppler shift θ _d is used only for calculating the integer portion of the rotation speed of the phase. Therefore, the communication system 100 of the present embodiment has an effect that deterioration of the channel estimation accuracy of the terminal 300 can be suppressed even when the accuracy or acquisition frequency of the position information or the moving speed is low. ..

Generally, a communicator contains only one carrier oscillator. For example, in the technique described in Patent Document 1, a Doppler shift is input to one internal oscillator (carrier wave oscillator), and the internal oscillator oscillates a frequency signal corrected for the Doppler shift. Therefore, when the communication device is performing one-to-n (n is an integer of 2 or more) communication, the Doppler shift correction for one communication device may adversely affect the communication with another communication device. On the other hand, in the communication system 100 of the present embodiment, the Doppler shift calculated by the phase calculation unit 400 is input to the channel interpolation unit 330. Therefore, in the communication system 100 of the present embodiment, it is possible to feed back the Doppler shift according to each communication device.
(Second Embodiment)
A second embodiment of the present invention based on the first embodiment of the present invention will be described. The first embodiment relates to downlink communication from the base station to the terminal, whereas the present embodiment relates to uplink communication from the terminal to the base station. The present embodiment may be used alone or in combination with the first embodiment.

The configuration in this embodiment will be described.

FIG. 11 is a block diagram showing an example of the configuration of the communication system according to the first embodiment of the present invention. As shown in FIG. 11, the communication system 101 of the present embodiment includes a base station 201 and a terminal 301. The base station 201 and the terminal 301 are connected by wireless communication. Hereinafter, the uplink signal (uplink) from the terminal 301 to the base station 201 will be described, and the downlink signal (downlink) from the base station 201 to the terminal 301 will be omitted.

FIG. 12 is a block diagram showing an example of the configuration of the terminal 301 according to the second embodiment of the present invention. As shown in FIG. 12, the terminal 301 includes a channel control unit 210, a transmission side wireless communication unit 221 and a phase calculation unit 400.

The transmitting side wireless communication unit 221 transmits transmission data including data symbols and pilot symbols input from the channel control unit 210 and the phase calculation unit 400 to the receiving side wireless communication unit 311 (described later) via radio waves. Here, the data symbol includes information on the Doppler shift (the phase of the received pilot symbol that changes due to the Doppler shift with the movement of the terminal 301) calculated by the phase calculation unit 400. Other configurations of the transmitting side wireless communication unit 221 are the same as the configuration of the transmitting side wireless communication unit 220 in the first embodiment.

Other configurations of the terminal 301 are the same as the configuration of the base station 200 in the first embodiment.

FIG. 13 is a block diagram showing an example of the configuration of the base station 201 according to the second embodiment of the present invention. As shown in FIG. 13, the base station 201 includes a receiving side radio communication unit 311, a channel estimation unit 320, a channel interpolation unit 330, and a data symbol demodulation unit 340.

The receiving side wireless communication unit 311 receives data symbols, pilot symbols, and the like from the transmitting side wireless communication unit 221 via radio waves. The receiving side wireless communication unit 311 outputs the Doppler shift information included in the data symbol received from the transmitting side wireless communication unit 221 to the channel interpolation unit 330. The receiving side wireless communication unit 311 outputs received data including data symbols, pilot symbols, etc. to the data symbol demodulation unit 340, the channel estimation unit 320, and the channel interpolation unit 330.

The channel interpolation unit 330 has a channel estimation value of the data symbol based on the channel estimation value of the pilot symbol input from the channel estimation unit 320 and the Doppler shift information included in the reception data input from the reception side wireless communication unit 311. To interpolate. The channel interpolation unit 330 outputs the interpolated channel to the data symbol demodulation unit 340.
Other configurations of the receiving-side wireless communication unit 311 are the same as the configuration of the receiving-side wireless communication unit 310 in the first embodiment.

Other configurations of the base station 201 are the same as the configuration of the terminal 300 in the first embodiment.

The operation in this embodiment will be described.

The communication system 101 of the present embodiment operates in the same manner as the first embodiment except that the Doppler shift is calculated on the transmitting side (terminal 301).

As described above, the communication system 101 of the present embodiment operates in the same manner as the first embodiment except that the Doppler shift is calculated on the transmitting side (terminal 301). Therefore, the communication system 101 of the present embodiment has the same effect as that of the first embodiment.
(Third Embodiment)
A third embodiment of the present invention, which is based on the first embodiment or the second embodiment of the present invention, will be described. In the first embodiment and the second embodiment, the Doppler shift is calculated based on the measured position and speed of the terminal, whereas in the present embodiment, the position and speed of the navigating body in which the terminal is present are calculated. The Doppler shift is calculated based on this.

The configuration in this embodiment will be described.

FIG. 14 is a block diagram showing an example of the configuration of the phase calculation device 402 according to the third embodiment of the present invention. As shown in FIG. 14, the phase calculation device 402 in the present embodiment includes a parameter acquisition unit 410, an operation information acquisition unit 472, a position information storage unit 430, a movement direction calculation unit 440, and a Doppler shift calculation unit 460. including. The phase calculation device 402 is a device that replaces the phase calculation unit 400 in the first embodiment and the second embodiment. That is, instead of the position information acquisition unit 420 and the speed information acquisition unit 450 of the phase calculation unit 400 in the first embodiment and the second embodiment, the operation information acquisition unit 472 is used in this embodiment.

The operation information acquisition unit 472 holds the operation information of the navigating body (train, aircraft, satellite, etc.) in which the terminal is located. The operation information acquisition unit 472 stores real-time position information and speed information of the navigating body moving together with the terminal by cooperating with an operation management system of a railway company, an aerospace company, or the like, for example. The operation information acquisition unit 472 outputs the position information of the navigation body to the position information storage unit 430 as the position information of the terminal. Further, the operation information acquisition unit 472 outputs the speed information of the traveling body to the Doppler shift calculation unit 460 as the speed information of the terminal. Here, for example, the movement (position and speed) of the terminal and the traveling body may be matched by limiting the reception range (cell) of the radio wave in the terminal.

Other configurations and operations of the phase calculation device 402 are the same as the configurations and operations of the phase calculation unit 400 in the first embodiment and the second embodiment.

As described above, the phase calculation device 402 in the present embodiment operates in the same manner as the phase calculation unit 400 in the first embodiment and the second embodiment. Therefore, the phase calculation device 402 in the present embodiment correctly calculates the phase difference corresponding to the Doppler shift without increasing the ratio of the pilot signal in the transmission signal even when the Doppler shift is large in wireless communication. It has the effect of being able to do it.

Further, the phase calculation device 402 in the present embodiment does not include the position information acquisition unit 420 and the speed information acquisition unit 450 in the first embodiment and the second embodiment. Therefore, the phase calculation device 402 in the present embodiment has an effect that the phase difference corresponding to the Doppler shift can be correctly calculated even when the GPS of the terminal, the acceleration sensor, or the like cannot be used.
(Fourth Embodiment)
A fourth embodiment of the present invention, which is the basis of each embodiment of the present invention, will be described.

The configuration in this embodiment will be described.

FIG. 15 is a block diagram showing an example of the configuration of the communication system 105, which is the operating environment of the phase computing device according to the fourth embodiment of the present invention. As shown in FIG. 15, the communication system 105 of the present embodiment includes a base station 205 and a terminal 305. The base station 205 and the terminal 305 are connected by wireless communication. The carrier used for wireless communication shall have a frequency _fc (predetermined value). Further, it is assumed that the repetition period of the pilot signal modulated on the carrier is the period T _s (predetermined value). Further, the position where the base station 205 exists is represented by the first position O. Further, the position where the terminal 305 existed is represented by the first position P', and the position where the terminal 305 existed after the movement of the terminal 305 is represented by the second position P. Further, the speed of the terminal 305 at the time of movement is expressed by the speed v. The terminal 305 includes a phase calculator 405.

FIG. 16 is a block diagram showing an example of the configuration of the phase calculation device 405 according to the fourth embodiment of the present invention. As shown in FIG. 16, the phase calculation device 405 of the present embodiment includes a movement direction calculation unit 445 and a Doppler shift calculation unit 465.

The operation in this embodiment will be described.

FIG. 17 is a flowchart showing the operation of the phase calculation device 405 according to the fourth embodiment of the present invention.

The movement direction calculation unit 445 calculates the direction of movement based on the information representing the first position P', the second position P, and the third position O (step S510).

The Doppler shift calculation unit 465 determines the Doppler shift due to the movement when the carrier is received, based on the information representing the direction, the speed v, the frequency f _c , and the period T _s calculated by the movement direction calculation unit 445. The corresponding phase difference in the received carrier is calculated (step S520). Here, the size of the range of possible values of the rotation speed representing the phase difference is larger than one rotation (the phase difference can also take a value larger than one rotation).

As described above, in the phase calculation device 405 of the present embodiment, the movement direction calculation unit 445 calculates the movement direction of the terminal 305. Then, the Doppler shift calculation unit 465 calculates the phase difference in the received carrier corresponding to the Doppler shift based on the calculated information indicating the direction and speed v of the movement. Here, the Doppler shift calculation unit 465 can calculate the phase difference even when the rotation speed representing the phase difference corresponding to the Doppler shift is one rotation or more. Therefore, in the Doppler shift calculation unit 465, it is not necessary to shorten the repetition period _Ts of the pilot signal in order to correctly calculate the phase difference. Therefore, the phase calculation device 405 of the present embodiment correctly calculates the phase difference corresponding to the Doppler shift without increasing the ratio of the pilot signal in the transmission signal even when the Doppler shift is large in wireless communication. It has the effect of being able to do it.

The Doppler shift calculation unit 465 may calculate an integer portion of the rotation speed representing the phase difference and use it as a calculation result of the phase difference. In this case, the fractional part of the rotation speed representing the phase difference is processed by the automatic frequency control function of the receiving side wireless communication means (for example, the receiving side wireless communication unit 310, 311).

Further, the moving direction calculation unit 445 may acquire information representing the first position P'and the second position P from the positioning system that performs the positioning of the terminal 305. Further, the moving direction calculation unit 445 may acquire information indicating the speed v of the terminal 305 from the acceleration sensor or speed sensor of the terminal 305 or the positioning system.

Further, the movement direction calculation unit 445 navigates from the operation management system that manages the position of the vehicle in which the terminal 305 exists as information indicating the speed v of the first position P', the second position P, and the terminal 305. Information on the position and speed of the runner may be obtained.

FIG. 18 is a block diagram showing an example of a hardware configuration capable of realizing the phase calculation unit 400 and the phase calculation devices 402 and 405 (hereinafter, referred to as “phase calculation device and the like”) in each embodiment of the present invention.

The phase calculation device and the like 901 include 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. Has been done. The storage device 902 stores the operation program of the CPU 903 of the phase calculation device or the like 901. The CPU 903 controls the entire phase calculation device 901, executes an operation program stored in the storage device 902, and executes the program of the phase calculation device 901 and transmits / receives data by the I / O device 908. The internal configuration of the phase calculation device and the like 901 is an example. The phase calculation device or the like 901 may have a device configuration in which a keyboard 904 and a monitor 905 are connected, if necessary.

The phase calculation device or the like 901 in each embodiment of the present invention described above may be realized by a dedicated device, but a computer (information) other than the operation of the hardware in which the I / O device 908 executes communication with the outside. It can also be realized by a processing device). 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 the respective parts such as the phase calculation device shown in FIGS. 6, 14 and 16 described above. However, it is assumed that each of these parts includes hardware as appropriate. 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 described in the claims.

INDUSTRIAL APPLICABILITY The present invention can be used in applications for correcting the influence of Doppler shift of a high-speed mobile terminal in wireless communication.

100, 101, 105 Communication system 200, 201, 205 Base station 210 Channel control unit 220, 221 Transmitter wireless communication unit 300, 301, 305 Terminal 310, 311 Receiver wireless communication unit 320 Channel estimation unit 330 Channel interpolation unit 340 data Symbol demodulation unit 400 Phase calculation unit 402, 405 Phase calculation device 410 Parameter acquisition unit 420 Position information acquisition unit 430 Position information storage unit 440, 445 Movement direction calculation unit 450 Speed information acquisition unit 460, 465 Doppler shift calculation unit 472 Operation information acquisition Part 510 D / A converter 520 Carrier wave oscillator 530 Multiplier 540 Amplifier 550 Antenna 610 A / D converter 620 Carrier wave oscillator 630 Multiplier 640 Amplifier 650 Antenna 901 Phase calculator, etc. 902 Storage device 903 CPU
904 Keyboard 905 Monitor 906 Internal Bus 908 I / O Device

Claims (9)

Based on information representing the first position where the terminal was present, information representing the second position where the terminal was present after the movement of the terminal, and information representing the third position where the base station that performs wireless communication with the terminal is present. Then, the movement direction calculation means for calculating the movement direction and
It represents the calculated directions, information representing the speed of the terminal during the movement, information representing the frequency of the carrier used for the radio communication, and the repetition period of the pilot signal modulated on the carrier. Based on the information, the Doppler shift calculation means for calculating the phase difference in the received carrier corresponding to the Doppler shift caused by the movement when the carrier is received is provided.
A phase calculator in which the size of the range of possible values of the rotation speed representing the phase difference is larger than one rotation. The phase calculation device according to claim 1, wherein the Doppler shift calculation means calculates an integer portion of the rotation speed and obtains the calculation result of the phase difference. The moving direction calculation means acquires information representing the first position and the second position from the positioning system that performs positioning of the terminal, and the acceleration sensor or speed sensor of the terminal, or the positioning system of the terminal. The phase calculation device according to claim 1 or 2, wherein the information indicating the speed is acquired. The moving direction calculating means is used as information indicating the speeds of the first position, the second position, and the terminal 305 from the operation management system that manages the position of the traveling body in which the terminal is present. The phase calculation device according to any one of claims 1 to 3, wherein the information regarding the position and speed of the above is acquired. The phase calculation device according to any one of claims 1 to 4.
A channel estimation means for estimating the channel of the pilot signal received from the base station, and
The channel of the data signal received from the base station is estimated based on the calculation result of the phase difference calculated by the phase calculator and the estimation result of the channel of the pilot signal estimated by the channel estimation means. Channel interpolation means and
A terminal provided with a data signal demodulation means for demodulating the data signal based on the estimation result of the channel of the data signal estimated by the channel interpolation means. The terminal according to claim 5 and
A communication system including the base station for transmitting the pilot signal and the data signal. The terminal also transmits another pilot signal and another data signal on the uplink from the terminal to the base station.
The other data signal in the uplink includes the calculation result of the phase difference calculated by the phase calculator.
The base station estimates the channels of the other pilot signal and the other data signal for the uplink based on the calculation result of the phase difference received from the terminal, and the base station estimates the channel based on the estimation result. The communication system according to claim 6, which demodulates another data signal. Based on information representing the first position where the terminal was present, information representing the second position where the terminal was present after the movement of the terminal, and information representing the third position where the base station that performs wireless communication with the terminal is present. Then, calculate the direction of the movement,
It represents the calculated directions, information representing the speed of the terminal during the movement, information representing the frequency of the carrier used for the radio communication, and the repetition period of the pilot signal modulated on the carrier. A phase calculation method for calculating the phase difference in the received carrier, which corresponds to the Doppler shift caused by the movement when the carrier is received, based on the information.
A phase calculation method in which the size of the range of possible values of the rotation speed representing the phase difference is larger than one rotation. For computers equipped with phase calculators
Based on information representing the first position where the terminal was present, information representing the second position where the terminal was present after the movement of the terminal, and information representing the third position where the base station that performs wireless communication with the terminal is present. Then, the movement direction calculation process for calculating the movement direction and
It represents the calculated directions, information representing the speed of the terminal during the movement, information representing the frequency of the carrier used for the radio communication, and the repetition period of the pilot signal modulated on the carrier. A phase calculation program for executing a Doppler shift calculation process for calculating a phase difference in the received carrier, which corresponds to the Doppler shift caused by the movement when the carrier is received, based on the information.
A phase calculation program in which the size of the range of possible values of the number of rotations representing the phase difference is larger than one rotation.

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