JP5199935B2 - Spatio-temporal channel simulator - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a performance evaluation apparatus used for performance evaluation of a mobile station in a mobile communication system, and in particular, a spatio-temporal channel simulator that enables simulation of multiwave fading by adding time-varying path fluctuations to a plurality of propagation path parameters. About.

  In general, it is not easy to evaluate characteristics of a mobile communication system in an actual propagation environment (outdoors), and an apparatus for evaluating and verifying in an indoor experimental system called a channel simulator is required. In a mobile communication environment with a low probability of establishing a line-of-sight condition between a base station and a mobile station, radio waves emitted from the base station repeatedly arrive at the mobile station after being reflected, diffracted, and scattered in the surrounding buildings. It is characterized by the spread in radio wave reception intensity (fading), delay time, emission direction, arrival direction, and polarization direction. Furthermore, in next-generation mobile communication systems such as Long Term Evolution (LTE) and IMT-Advanced, the adoption of multi-antenna technology (MIMO transmission / adaptive array) that actively uses the spatial distribution characteristics of radio waves is promising. Therefore, it is important to simulate the spatial distribution characteristics of radio waves in a channel simulator.

  A channel simulator disclosed in Patent Document 1 is known as a channel simulator that takes into account the spatial distribution characteristics of radio waves generated by the movement of a mobile station, that is, the time variation characteristics of propagation path parameters due to path shielding. FIG. 10 shows a functional configuration of the conventional channel simulator 9 and its operation will be briefly described. The channel simulator 9 is described as a time-varying multipath generation device 9 in Patent Document 1.

  The channel simulator 9 includes an input device 1, a parameter input / control unit 2, a data storage unit 3, a random number generation unit 4, a path generation unit 5, a time varying function generation unit 6, an output data buffer memory 7, and an output interface unit 8. . The data storage unit 3 stores a path generation parameter file, a time-varying function file, an antenna directivity pattern file, an incoming wave direction density function file, and a distribution function file. The path generation parameter is a value such as an average value and standard deviation of the shielding time interval, an average value and standard deviation of the shielding amplitude, and the like. The time-varying function file stores a plurality of functions of shielding variation with respect to the amplitude and phase of the path input from the parameter input / control unit 2. The arrival wave direction density function file stores a plurality of probability density functions that define path occurrence probabilities with respect to the arrival wave direction. Thus, the data stored in each file of the data storage unit 3 is a statistical model prepared in advance.

  The path generation unit 5 generates a path in response to a generation request from the parameter input / control unit 2. In this method, as many propagation path parameters as the number of propagation paths are generated on the basis of the random numbers generated by the random number generation unit 4 with reference to the parameters stored in the data storage unit 3.

JP 2004-254250 A (FIG. 3)

  In the conventional channel simulator 9, the propagation path parameter used for the simulation is a statistical model. Therefore, there is a problem that it is not possible to evaluate a mobile station that simulates a specific radio wave situation in an actual site.

  The present invention has been made in view of these points, and an object thereof is to provide a spatio-temporal channel simulator that generates propagation parameters for evaluating a mobile station based on radio wave propagation characteristics measured in an actual communication environment. And

The spatiotemporal channel simulator of the present invention includes a measurement unit and a reproduction unit. The measurement unit measures the radio wave propagation characteristics between the base station and the mobile station in the mobile communication system and its own movement vector. The reproduction unit receives the radio wave propagation characteristic, the movement vector, and the input simulated base station signal, and generates the propagation characteristic of the propagation path simulating the real environment using the propagation parameter extracted from the radio wave propagation characteristic. The reproduction unit inputs the propagation characteristics of the propagation path, the number of propagation paths, which is the number of propagation paths, the emission angle, the arrival angle, the complex amplitude, and the delay time of the propagation paths. As a propagation parameter extraction unit.

  According to the spatiotemporal channel simulator of the present invention, the measurement unit measures the radio wave propagation characteristics at the actual site, and the reproduction unit generates the propagation parameters for evaluating the mobile station from the actually measured radio wave propagation characteristics. Enables mobile station evaluation in a close environment.

The figure which shows the function structural example of the space-time channel simulator 100 of this invention. The figure which shows notionally the situation of an example in which the space-time channel simulator 100 is used. The figure which shows the more concrete function structural example of the space-time channel simulator 100. FIG. The figure which shows the operation | movement flow of the space-time channel simulator 100. FIG. The figure which shows notionally the propagation parameter which can be defined between the base station 50 and the mobile station 51. The figure which shows the more concrete functional structural example of each conversion part of the space-time channel simulator 100. FIG. The figure which shows the function structural example of the space-time channel simulator 700 of this invention. The figure which shows an example of the usage condition of the space-time channel simulator. The figure which shows notionally the operation | movement of the path degeneration matrix conversion part 71. FIG. The figure which shows the function structure of the conventional channel simulator 9. FIG.

  Embodiments of the present invention will be described below with reference to the drawings. The same reference numerals are given to the same components in a plurality of drawings, and the description will not be repeated.

FIG. 1 shows an example of the functional configuration of the space-time channel simulator 100 of the present invention. Space-time channel simulator 100 includes a radio wave propagation characteristic X _R between a base station and a mobile station in a mobile communication system, a measuring unit 10 which measures the motion vector d of the own radio wave propagation characteristic X _R, movement vector and d, as inputs an input simulated base station signal X _S, includes a radio wave propagation characteristic reproducing unit 20 for a real environment to generate the propagation characteristics of the propagation paths simulating using the propagation parameters extracted from X _R, a.

Measurement unit 10, for example by receiving a radio signal from the base station inputted from the plurality of antennas based on multi-antenna technology, its addition to measuring the radio wave propagation characteristic X _R between the base station and the measuring unit 10 The movement vector d is measured. The movement vector d may be obtained from, for example, coordinate information received by a GPS receiver provided in the measurement unit 10, or a movement vector d is autonomously generated by including a gyroscope or an accelerometer in the measurement unit 10. May be.

Thus reproducing unit 20 of the space-time channel simulator 100 is input with propagation characteristics X _R and motion vector d and the input simulated base station signal X _S, the actual environment using the propagation parameters extracted from the radio wave propagation characteristic X _R Propagation characteristics of a propagation path that simulates Therefore, the mobile station can be evaluated in a more realistic environment.

  FIG. 2 conceptually illustrates an example situation in which the space-time channel simulator 100 is used. The measurement vehicle 200 is loaded with the spatio-temporal channel simulator 100 and travels on a road where a building in an urban area, which is a target environment for which a mobile station is desired to be evaluated, stands. The spatiotemporal channel simulator 100 receives radio waves that are radiated from a plurality of base stations while the measurement vehicle 200 is running, reflected and diffracted by an obstacle such as a building or terrain, and a multipath is generated.

Measuring section 10 measures a movement vector d of the radio wave propagation characteristic X _R and the measurement vehicle 200 from the radio wave state that Paruchipasu occurs. Reproducing unit 20 extracts the propagation parameter from the radio wave propagation characteristic X _R and motion vector d, to generate the propagation characteristics of a plurality of propagation paths. Be previously prepared mobile station to be evaluated in the measurement vehicle 200, by inputting an input simulated base station signal X _S in the reproduction unit 20, it is possible to evaluate the mobile station on the fly. By using the space-time channel simulator 100, it is possible to speedily evaluate a mobile station after quantitatively grasping a radio wave condition in an actual environment.

Also, down the space-time channel simulator 100 from the measurement vehicle 200, by inputting an input simulated base station signal X _S in the laboratory, to enable the evaluation of a mobile station in a more realistic environment. As described above, the spatio-temporal channel simulator 100 has an excellent effect of making the mobile station evaluation flexible and accurate. It is not always necessary to move the spatiotemporal channel simulator 100 from the measurement vehicle 200. The same spatiotemporal channel simulator 100 may be prepared in the laboratory, and the propagation parameter and the movement vector d may be moved from the on-vehicle spatiotemporal channel simulator 100 via a recording medium.

  The operation of the space-time channel simulator 100 will be described in more detail with reference to FIG. 3 showing a specific functional configuration example. FIG. 4 shows the operation flow. The measurement unit 10 includes a reception unit 11 and a position / movement direction measurement unit 12. The playback unit 20 includes a propagation parameter extraction unit 21, a base station signal conversion unit 24, a propagation mode conversion unit 25, a mobile station signal conversion unit 26, and a control unit 27.

The receiving unit 11 outputs the radio wave propagation characteristics to the reproducing unit 20 (step S11). The position / movement direction measuring unit 12 outputs the movement vector d to the reproducing unit 20 (step S12). The propagation parameter extraction unit 21 uses the number L of propagation paths, the emission angle φ _i of these propagation paths L, the arrival angle ψ _i , the complex amplitude α _i, and the delay time τ _i as propagation parameters from the radio wave propagation characteristics. Extract (step S21).

Here, each propagation parameter will be described with reference to FIG. FIG. 5 is a diagram conceptually illustrating propagation parameters that can be defined between the base station 50 and the mobile station 51. The propagation path number L is the number of straight arrows shown in FIG. The outgoing angle φ _i is an angle in a coordinate system with the center of the base station antenna as the origin. The complex amplitude α _i and the delay time τ _i are values for each propagation path. The arrival angle ψ _i is an angle in a coordinate system with the origin of the center of the mobile station antenna.
With these propagation parameters, the channel response h _i ^{(n, m)} (i = 1,..., L) of each propagation path L can be expressed by equation (1).

Here, φ _i ￣ (the expression and the notation in the figure are correct) is a unit vector in the outgoing direction, and ψ _i ￣ is a unit vector in the direction of arrival. m represents a specific one of the M antennas of the base station 50. n represents a specific one of N mobile station antennas. k ₀ is the wave number (2π / wavelength). d is a movement vector (a size is a distance and a direction is equivalent to a movement direction).

The channel response considering the L propagation paths can be expressed as a matrix H whose elements are channel responses h _i ^{(n, m)} of the respective propagation paths, and the matrix H is represented by three channel response matrices shown in Expression (2). Can be divided into

Here, H _R is a mobile station-side steering matrices with N rows × L columns representing the phase relationship of the propagation path of the mobile station side. Each element of the matrix is calculated by Equation (3) and represents the phase relationship of the propagation path on the mobile station side.

H _L is a diagonal matrix of propagation path constant β _i composed of complex amplitude α _i , delay time τ _i, etc., and each element is calculated by equation (4).

H _T is a base station side steering matrix of the number M of base station antennas × the number of propagation paths L columns, and each element is calculated by Expression (5). H _T represents the phase relationship of the propagation path on the base station side.

The reproducing unit 20 generates propagation characteristics composed of a plurality of propagation paths using these channel response matrices H _R , H _L and H _T and outputs a mobile station evaluation signal Y. The base station signal converter 24 receives as input the input simulated base station signal X _{S using} the propagation path number L, the propagation path emission angle φ _i , the position information S of the base station antenna, and the input simulated base station signal X _S as inputs. Is converted into a simulated base station signal H _T X _S corresponding to the base station antenna position information S (step S24).

The propagation mode conversion unit 25 includes a simulated base station signal H _{TX S} , a propagation path number L, a movement vector d, a propagation path delay time τ _i , a propagation path complex amplitude α _i, and a propagation path arrival angle. ψ a _i as input, converts the simulated base station signal _H T-propagation pass signal _{X S} considering moving speed and direction of its _H L _H T _{X S} (step S25).

The mobile station signal conversion unit 26 receives the propagation path signal H _L H _T X _S , the antenna position information u of the mobile station, the number L of propagation paths, and the propagation path arrival angle ψ _i, and receives the propagation path signal H _L. H _T X _S is converted into a mobile station evaluation signal Y for evaluating the mobile station by wired connection and output (step S26).

Each conversion unit 24-26 can be decomposed into the configuration of each matrix generation unit 240-260 and each matrix multiplication unit 241-261. FIG. 6 shows an example of the configuration. The base station signal conversion unit 24 includes a base station side steering matrix generation unit 240 and a base station side steering matrix multiplication unit 241. The base station side steering matrix generation unit 240 generates the base station side steering matrix H _T shown in Expression (2) by using the propagation path number L and the emission angle φ _i of the propagation path L as inputs (step S240). Base station side steering matrix multiplication unit 241 multiplies the base station-side steering matrix _{H T} to the input simulated base station signal _{X S} into a simulated base station signal _H T _{X S} (step S241).

The propagation mode conversion unit 25 includes a propagation mode matrix generation unit 250 and a propagation mode matrix multiplication unit 251. The propagation mode matrix generation unit 250 receives, as inputs, the number of propagation paths L, the movement vector d, the propagation path delay time τ _i , the propagation path complex amplitude α _i, and the propagation path arrival angle ψ _i. The propagation mode matrix _HL shown in 2) is generated (step S250). The propagation mode matrix multiplication unit 251 generates a propagation path signal H _L H _T X _S by multiplying the simulated base station signal H _T X _S by the propagation mode matrix H _L (step S251).

The mobile station signal conversion unit 26 includes a mobile station side steering matrix generation unit 260 and a mobile station side steering matrix multiplication unit 261. The mobile station side steering matrix generation unit 260 receives the propagation path number L, the propagation path arrival angle ψ _i, and the mobile station antenna position information u as inputs, and the mobile station side steering matrix H _R shown in Expression (2). Is generated (step S260). The mobile station side steering matrix multiplier 261 multiplies the propagation path signal H _L H _T X _S by the mobile station side steering matrix H _R to generate a mobile station evaluation signal Y for evaluating the mobile station by wired connection (step S261). .

As described above, the space-time channel simulator 100 obtains a propagation parameter from the actually measured radio wave propagation characteristics between the base station and the mobile station, and generates an evaluation signal of the mobile station using the propagation parameter. Enables mobile station evaluation in a more realistic environment. In addition, the space-time channel simulator 100 introduces the idea of dividing a plurality of propagation path channel responses h _i ^{(n, m)} into three channel response matrices. This concept makes it possible to easily set conditions for each propagation path on the base station side and mobile station side. This means that a finer evaluation of a mobile station can be easily performed based on actual radio wave propagation characteristics.

  In addition, although each conversion part 24-26 demonstrated in the example which uses the propagation parameter extracted from the radio wave propagation characteristic as it is, you may process and use a propagation parameter. The configuration is shown by broken lines in FIGS. The model parameter generation unit 22 calculates the average and variance of the propagation parameters extracted by the propagation parameter extraction unit 21, for example. The random number generator 23 generates random numbers according to a normal distribution or a rectangular distribution, for example. The model parameter generation unit 22 varies the propagation parameter according to the random number and outputs it. The cycle of outputting the fluctuation is controlled by the control unit 27. As described above, each propagation parameter actually measured may be changed with time, and the mobile station evaluation signal Y with time-varying path fluctuation that changes with time may be output.

  It is also possible to evaluate mobile stations over a wireless connection. Next, the operation of the space-time channel simulator 700 in which the mobile station is evaluated by wireless connection will be described as a second embodiment.

  FIG. 7 shows a functional configuration example of the space-time channel simulator 700 of the second embodiment. The space-time channel simulator 700 is configured to evaluate a mobile station by wireless connection, and the mobile station signal conversion unit 26 of the space-time channel simulator 100 of the first embodiment is replaced with a path degenerate matrix conversion unit 71, and a plurality of The difference is that each of the scattering elements 80 (see FIG. 8) is provided. Note that an amplifier, a filter, and the like provided between the path degenerate matrix conversion unit 71 and the scattering element 80 are omitted.

  FIG. 8 shows an example of how the space-time channel simulator 700 is used. There are a plurality of scattering elements 80, and the output signal of the path degenerate matrix conversion unit 71 is connected to each scattering element 80. In this example, the number of scattering elements 80 is twelve. In the center of the twelve scattering elements 80, for example, a mobile station 51 to be evaluated and a human phantom 82 are arranged as necessary.

The path degenerate matrix conversion unit 71 includes a propagation path signal H _L H _T X _S output from the propagation mode conversion unit 25, a propagation path number L output from the propagation parameter extraction unit 21, a propagation path arrival angle ψ _i , Using the scattering element number information K as an input, the propagation path signal H _L H _T X _S is converted into a path degenerate signal for evaluating the mobile station by wireless connection.

Path degenerate matrix transformation unit 71, a propagation path signal H _LT X _S and pass degenerate matrix generating section 711 for generating a pass degenerate matrix H _K propagation path number L and the scattering element number K as an input, the propagation path signal H _L H A path degeneration matrix multiplication unit 712 that multiplies _T X _S by a path degeneration matrix H _K to generate a path degeneration signal Y ′ for evaluating a mobile station by wireless connection.

FIG. 9 conceptually shows the operation of the path degenerate matrix conversion unit 71. The path degenerate matrix conversion unit 71 performs an operation of aggregating the propagation path signals H _L H _T X _S into the number of scattering elements 80. FIG. 9 shows an example of a value L / K = 4 obtained by dividing the number of propagation paths L by the number K of scattering elements. That is, a state where 48 propagation paths are aggregated into 12 is conceptually shown.
Path degenerate matrix _{H K} is given by Equation (6).

The matrix μ is a matrix in which 1 of L / K numbers are arranged. In the example shown in FIG. 9, four 1s are arranged.
As described above, the spatio-temporal channel simulator 700 enables evaluation of a mobile station by wireless connection using propagation parameters based on radio wave propagation characteristics in an actual site. As a result, a more detailed simulation including the influence of the human body is possible.

The apparatus of the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention. For example, a recording unit that records the propagation parameter extracted by the propagation parameter extraction unit 21 and the movement vector d may be provided. By sequentially reading data from the recording unit, it is possible to repeatedly evaluate mobile stations in different environments.

Further, the processes described in the above method and apparatus are not only executed in time series according to the order of description, but also may be executed in parallel or individually as required by the processing capability of the apparatus that executes the processes. Good. Further, the processing means in the above apparatus may be realized by a computer. In that case, the processing content of the function that each unit should have is described by a program. Then, by executing this program on the computer, the processing means in each apparatus is realized on the computer. Further, at least a part of these processing means may be realized by hardware.

Claims (5)

A measurement unit that measures radio wave propagation characteristics between a base station and a mobile station in a mobile communication system and its own movement vector;
A reproduction unit that generates the propagation characteristics of a propagation path that simulates the real environment using the propagation parameters extracted from the radio wave propagation characteristics, using the radio wave propagation characteristics, the movement vector, and the input simulated base station signal as inputs,
A spatial channel simulator when including a,
The reproduction unit inputs the propagation characteristics of the propagation path, the number of propagation paths, which is the number of propagation paths, the emission angle, the arrival angle, the complex amplitude, and the delay time of the propagation paths. Propagation parameter extraction unit to extract as
A spatiotemporal channel simulator characterized by comprising: In the spatiotemporal channel simulator according to claim 1 ,
A simulated base station signal in which the input simulated base station signal, the number of propagation paths, the emission angle of the propagation path, and the antenna position information of the base station are input, and the input simulated base station signal is associated with the base station antenna position information. A base station signal converter for converting to
Using the simulated base station signal, the number of propagation paths, the movement vector, the delay time of the propagation path, the complex amplitude of the propagation path, and the arrival angle of the propagation path as input, the simulated base station signal is A propagation mode conversion unit for converting into a propagation path signal in consideration of the direction;
A mobile station signal for converting the propagation path signal into a mobile station evaluation signal for evaluating the mobile station by wired connection, with the propagation path signal, the antenna position information of the mobile station, the number of propagation paths, and the arrival angle of the propagation path as inputs. A conversion unit;
A spatio-temporal channel simulator characterized by further comprising: In the spatiotemporal channel simulator according to claim 2 ,
The base station signal conversion unit includes a base station side steering matrix generation unit that generates a base station side steering matrix by using the number of propagation paths and an emission angle of the propagation path as inputs, and the base station side to the input simulated base station signal. A base station side steering matrix multiplier for multiplying the side steering matrix to generate a simulated base station signal,
The propagation mode conversion unit generates a propagation mode matrix by using the number of propagation paths, the movement vector, the delay time of the propagation path, the complex amplitude of the propagation path, and the arrival angle of the propagation path as inputs. And a propagation mode matrix multiplication unit that multiplies the simulated base station signal by the propagation mode matrix to generate a propagation path signal,
The mobile station signal conversion unit includes a mobile station side steering matrix generation unit configured to generate a mobile station side steering matrix by using the propagation path signal, mobile station antenna position information, the number of propagation paths, and the arrival angle of the propagation path as inputs. A mobile station side steering matrix multiplier for generating a mobile station evaluation signal for multiplying the propagation path signal by the mobile station side steering matrix to evaluate the mobile station by wired connection,
Spatiotemporal channel simulator characterized by that. In the spatiotemporal channel simulator according to claim 1 ,
A simulated base station signal in which the input simulated base station signal, the number of propagation paths, the emission angle of the propagation path, and the antenna position information of the base station are input, and the input simulated base station signal is associated with the base station antenna position information. A base station signal converter for converting to
Using the simulated base station signal, the number of propagation paths, the movement vector, the delay time of the propagation path, the complex amplitude of the propagation path, and the arrival angle of the propagation path as input, the simulated base station signal is A propagation mode conversion unit for converting into a propagation path signal in consideration of the direction;
A path degenerate signal converter for converting the propagation path signal into a path degenerate signal for evaluating a mobile station by wireless connection, using the propagation path signal, the number of propagation paths, and the number of scattering elements as inputs;
A spatio-temporal channel simulator characterized by further comprising: In the spatiotemporal channel simulator according to claim 4 ,
The base station signal conversion unit includes a base station side steering matrix generation unit that generates a base station side steering matrix by using the number of propagation paths and an emission angle of the propagation path as inputs, and the base station side to the input simulated base station signal. A base station side steering matrix multiplier for multiplying the side steering matrix to generate a simulated base station signal,
The propagation mode conversion unit generates a propagation mode matrix by using the number of propagation paths, the movement vector, the delay time of the propagation path, the complex amplitude of the propagation path, and the arrival angle of the propagation path as inputs. And a propagation mode matrix multiplication unit that multiplies the simulated base station signal by the propagation mode matrix to generate a propagation path signal,
The path degenerate signal conversion unit receives the propagation path signal, the number of propagation paths, and the number of scattering elements, and generates a path degenerate matrix, and multiplies the propagation path signal by the path degeneration matrix. A path degeneration matrix multiplication unit for generating a path degeneration signal for evaluating a mobile station by wireless connection,
Spatiotemporal channel simulator characterized by that.

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