Test system and transmit antenna correlation estimation method

Abstract

To provide a test system and a transmit antenna correlation estimation method that can accurately calculate transmit antenna correlation by analyzing a reference signal such as a DMRS that has been precoded.SOLUTION: A test system 1 includes a real propagation path estimation characteristic calculation unit 21 that calculates estimated characteristics of the propagation path characteristics of a real propagation path, a real propagation path channel capacity calculation unit 29 that calculates the real propagation path channel capacity of the real propagation path from the estimated characteristics, a pseudo propagation path characteristic calculation unit 32 that calculates pseudo propagation path characteristics of a channel model, a pseudo channel capacity calculation unit 30 that calculates the pseudo channel capacity of the channel model from the pseudo propagation path characteristics, a transmitting antenna correlation coefficient estimation unit 27 that estimates a transmitting antenna correlation coefficient that makes the difference between the real propagation path channel capacity and the pseudo channel capacity smaller than a specified value, and a transmitting antenna correlation calculation unit 25 that calculates the transmitting antenna correlation on the basis of the transmitting antenna correlation coefficient estimated by the transmitting antenna correlation coefficient estimation unit 27.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a test system using a channel model and a method for estimating correlation between transmitting antennas. [Background technology]

[0002] When testing a mobile phone terminal (User Equipment: UE), the demodulation performance in a fading environment is evaluated by passing the downlink signal output from a base station simulator through a propagation path simulator and supplying the signal to the mobile radio terminal. The channel model used in the propagation path simulator is often one defined specifically for testing. However, there is also a demand for evaluating the UE demodulation performance using a channel model with propagation path characteristics closer to the actual propagation path environment.

[0003] Generally, as a method for simulating an actual propagation path environment, a method of reproducing the propagation path characteristics measured in the actual propagation path environment is known.

[0004] The ACE RNX Channel Emulator's "Field-to-Lab" (see, for example, Non-Patent Document 1) collects data on downlink signals transmitted by actual base stations as they travel through actual propagation paths, extracts the propagation path characteristics of the actual propagation paths by analyzing the data, and reproduces the instantaneous values ​​of the propagation path characteristics of the actual propagation paths to test the demodulation unit of the UE. "Field-to-Lab" can faithfully reproduce the actual propagation path characteristics by reproducing them exactly as they are.

[0005] However, the existing "Field-to-Lab" method disclosed in Non-Patent Document 1 reproduces the actual propagation path characteristics as they are, so the UE test time is determined by the data collection time. Also, since the antenna used to collect data is different from the antenna of the actual UE, there is no significant point in reproducing the instantaneous values ​​of the propagation path characteristics themselves.

[0006] Therefore, as shown in FIG. 8, it is conceivable to collect downlink signals transmitted from an actual base station 100 to a UE 10a (or an air monitor 10b) using the air monitor 10b or the like, and analyze the reference signals (RS) contained in the collected signals to calculate the parameters of a channel model in a MIMO (Multiple Input Multiple Output) propagation path simulator in the test environment, and perform a test using a fading model that is close to the real environment. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] "ACE RNX Channel Emulator" product catalog, March 1, 2018 Summary of the Invention [Problem to be solved by the invention]

[0008] One of the parameters of a channel model is the transmit antenna correlation. However, when calculating the parameters of a channel model using a channel that is precoded in the transmitter of a base station, for example, a DMRS (Demodulation Reference Signal) of a PDSCH, which is mainly a data channel, it is difficult to directly calculate the transmit antenna correlation for the following reasons.

[0009] For example, in a fourth-generation mobile phone system (LTE-Advanced) with Transmission mode={8,9} or a fifth-generation mobile phone system (5G NR), when base station 100 transmits a PDSCH as a downlink signal, a DMRS is transmitted together with user data, as shown in Fig. 8. At this time, common precoding is applied to the user data and the DMRS for each layer by precoder 130. In other words, since precoding is integrated with propagation path characteristics, it is not possible to distinguish between propagation path characteristics and precoding from a signal received by air monitor 10b or the like.

[0010] For example, as shown in Fig. 8, a different precoding matrix may be applied to each subband on the frequency axis or each symbol on the time axis. Since the relative phase between the transmitting antennas of base station 100 depends on the precoding matrix, when attempting to directly calculate the transmitting antenna correlation as defined, it has conventionally been impossible to accurately estimate the transmitting antenna correlation of the propagation path by eliminating the phase shift caused by the different precoding matrices for each subband or symbol.

[0011] The effect of precoding on transmit antenna correlation can be explained as follows.

[0012] As shown in the following equation (1), the transmit antenna correlation is defined as a transmit antenna correlation matrix that indicates the correlation between the propagation path characteristics from multiple transmit antennas Tx#1 to Tx#4 to one receive antenna Rx#y. Figure 9 shows the propagation path characteristics when the number of transmit antennas Tx is four.

[0013]

number

[0014] In equation (1), k is an index in the frequency axis direction, for example, an index of a subcarrier number. Also, n is an index in the time axis direction, for example, an index of an OFDM (Orthogonal Frequency Division Multiplexing) symbol number. Here, k is an integer from 1 to K, and n is an integer from 1 to N. Also, the propagation path characteristic h yx (k,n) The average power of is assumed to be normalized to 1.

[0015] The value of the x1 row x2 column element in the above transmit antenna correlation matrix for k and n is yx1 (k,n) and h yx2 (k,n) The correlation coefficient is calculated as the correlation coefficient between h yx1 (k,n) and h yx2 (k,n) It depends on the relative phase between

[0016]

number

[0017] Here, the relative phase in equation (2) is the phase ∠h yx1(prc) (k,n) ,∠h yx2(prc) (k,n) and the phase ∠h due to the MIMO propagation path yx1(ch) (k,n) ,∠h yx2(ch) (k,n) Contains:

[0018] Therefore, the x1 row x2 column element of the transmitting antenna correlation matrix is ​​expressed as in the following equation (3).

[0019]

number

[0020] As shown in Figure 8, the phase ∠h yx1(prc) (k,n) ,∠h yx2(prc) (k,n) can have different values ​​depending on the subcarrier number k and the OFDM symbol number n, so it is clear from equation (3) that the transmit antenna correlation of the MIMO propagation path itself cannot be directly calculated.

[0021] The present invention has been made to solve the above-mentioned problems in the past, and aims to provide a test system and a transmit antenna correlation estimation method that can analyze a reference signal such as a precoded DMRS and accurately calculate transmit antenna correlation. [Means for solving the problem]

[0022] In order to solve the above problem, the test system according to the present invention is a test system for transmitting signals from a plurality of transmitting antennas (Tx#1 to Tx#N) of a network-side transmitting / receiving device (100). TxAnt ) is transmitted to one or more receiving antennas (Rx#1 to Rx#N) in the environment of the actual propagation path (110). RxAnta real propagation path estimated characteristics calculation unit (21) that calculates estimated characteristics of the propagation path characteristics of the real propagation path using a reference signal included in IQ data of the downlink signal output from an antenna device (10) that receives the downlink signal via a reference signal input to the antenna device (10), a real propagation path channel capacity calculation unit (29) that calculates an actual propagation path channel capacity of the real propagation path from the estimated characteristics, a K factor calculation unit (24) that calculates a K factor from the estimated characteristics, a receiving antenna correlation calculation unit (26) that calculates a receiving antenna correlation that is a correlation between the estimated characteristics from each of the transmitting antennas to the one or more receiving antennas, and a transmitting antenna correlation matrix (27) that calculates the transmitting antenna correlation that is the correlation between the estimated characteristics from the plurality of transmitting antennas to each of the receiving antennas, the transmitting antenna correlation matrix (27) that changes in accordance with a transmitting antenna correlation coefficient. a pseudo channel characteristic calculation unit (32) that calculates pseudo channel characteristics of a channel model based on the K factor, the transmitting antenna correlation, and the receiving antenna correlation; a pseudo channel capacity calculation unit (30) that calculates pseudo channel capacity of the channel model from the pseudo channel characteristics; and a transmitting antenna correlation coefficient estimation unit (27) that estimates the transmitting antenna correlation coefficient such that a difference between the actual channel capacity and the pseudo channel capacity becomes smaller than a specified value, and the transmitting antenna correlation calculation unit is configured to calculate the transmitting antenna correlation by substituting the transmitting antenna correlation coefficient estimated by the transmitting antenna correlation coefficient estimation unit into the transmitting antenna correlation matrix.

[0023] With this configuration, the test system according to the present invention calculates the transmitting antenna correlation so that the actual propagation path channel capacity calculated based on the RS included in the IQ data of the downlink signal propagating from the actual base station to the antenna device is equivalent to the pseudo channel capacity calculated by the channel model.

[0024] As a result, the test system according to the present invention can analyze RSs such as precoded DMRSs and estimate transmit antenna correlation with high accuracy.

[0025] Furthermore, the test system according to the present invention can perform a throughput test of the device under test using a channel model that can obtain a throughput equivalent to that of an actual MIMO propagation path.

[0026] Furthermore, the test system according to the present invention can test the device under test by reproducing the statistical propagation path characteristics of an actual propagation path using the pseudo propagation path characteristics.

[0027] The test system according to the present invention may further include a relative phase estimation unit (28) that calculates an estimate of a relative phase between each of the receiving antennas of direct waves of the downlink signals from the plurality of transmitting antennas, and the pseudo-path characteristic calculation unit may be configured to calculate the pseudo-path characteristic consisting of a sum of a direct wave component that includes the estimate of the relative phase of the direct wave and a scattered wave component that does not include the estimate of the relative phase of the direct wave.

[0028] With this configuration, the test system according to the present invention can calculate a pseudo channel capacity that reflects the phase relationship of the direct wave components, similar to the phase relationship of the actual IQ data.

[0029] Furthermore, the test system according to the present invention may be configured such that the receiving antenna correlation calculation unit calculates the receiving antenna correlation so as to eliminate the influence of a direct wave component including an estimated value of the relative phase of the direct wave.

[0030] The transmitting antenna correlation estimation method according to the present invention is also directed to a method for estimating correlation between a plurality of transmitting antennas (Tx#1 to Tx#N) of a transmitting / receiving device (100) on the network side. TxAnt ) is transmitted to one or more receiving antennas (Rx#1 to Rx#N) in the environment of the actual propagation path (110). RxAntan actual propagation path estimated characteristics calculation step (S22) of calculating estimated characteristics of the propagation path characteristics of the actual propagation path using a reference signal included in IQ data of the downlink signal output from an antenna device (10) receiving the downlink signal at a receiving antenna correlation matrix (10) via a transmitting antenna correlation coefficient; an actual propagation path channel capacity calculation step (S23) of calculating actual propagation path channel capacity of the actual propagation path from the estimated characteristics; a K factor calculation step (S24) of calculating a K factor from the estimated characteristics; a receiving antenna correlation calculation step (S26) of calculating a receiving antenna correlation which is a correlation between the estimated characteristics from each of the transmitting antennas to the one or more receiving antennas; and calculating the transmitting antenna correlation which is a correlation between the estimated characteristics from the plurality of transmitting antennas to each of the receiving antennas by a transmitting antenna correlation matrix which changes according to the transmitting antenna correlation coefficient. a transmitting antenna correlation calculation step (S28), a pseudo propagation path characteristic calculation step (S3, S6, S13) of calculating pseudo propagation path characteristics of a channel model based on the K factor, the transmitting antenna correlation, and the receiving antenna correlation, a pseudo channel capacity calculation step (S3, S6, S13) of calculating pseudo channel capacity of the channel model from the pseudo propagation path characteristics, and a transmitting antenna correlation coefficient estimation step (S27) of estimating the transmitting antenna correlation coefficient such that a difference between the actual propagation path channel capacity and the pseudo channel capacity is smaller than a specified value, and the transmitting antenna correlation calculation step is configured to calculate the transmitting antenna correlation by substituting the transmitting antenna correlation coefficient estimated in the transmitting antenna correlation coefficient estimation step into the transmitting antenna correlation matrix.

[0031] Furthermore, the transmitting antenna correlation estimation method according to the present invention may further include a relative phase estimation step (S25) of calculating an estimated value of a relative phase between each of the receiving antennas of direct waves of the downlink signals from the plurality of transmitting antennas, and the pseudo-path characteristic calculation step may be configured to calculate the pseudo-path characteristic consisting of a sum of a direct wave component including the estimated value of the relative phase of the direct wave and a scattered wave component not including the estimated value of the relative phase of the direct wave.

[0032] Furthermore, the transmitting antenna correlation estimation method according to the present invention may be configured so that the receiving antenna correlation calculation step calculates the receiving antenna correlation so as to eliminate the influence of a direct wave component including an estimated value of the relative phase of the direct wave. [Effects of the Invention]

[0033] The present invention provides a test system and a transmit antenna correlation estimation method that can accurately calculate transmit antenna correlation by analyzing a reference signal such as a precoded DMRS. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 2 is a diagram schematically illustrating an environment of an actual propagation path between a base station and an antenna device. [Figure 2] 1 is a block diagram showing a configuration of a test system according to an embodiment of the present invention; [Figure 3] FIG. 10 is a diagram for explaining the definition of a receiving antenna correlation matrix. [Figure 4] 10 is a graph for explaining processing by a transmitting antenna correlation coefficient estimation unit. [Figure 5] 10(a) is a graph for explaining the processing of the transmitting antenna correlation coefficient estimation unit when the pseudo channel capacity is larger than the actual propagation path channel capacity, and FIG. 10(b) is a graph for explaining the processing of the transmitting antenna correlation coefficient estimation unit when the pseudo channel capacity is smaller than the actual propagation path channel capacity. [Figure 6] 10 is a flowchart illustrating an example of specific processing by a transmitting antenna correlation coefficient estimator, a pseudo channel capacity calculator, and a pseudo propagation path characteristics calculator. [Figure 7] 1 is a flowchart illustrating a process of a transmitting antenna correlation estimation method using a test system according to an embodiment of the present invention. [Figure 8] FIG. 10 is a diagram for explaining precoding applied in a transmitting unit of a base station. [Figure 9] FIG. 10 is a diagram for explaining the definition of a transmission antenna correlation matrix. DETAILED DESCRIPTION OF THE INVENTION

[0035] Hereinafter, embodiments of a test system and a transmitting antenna correlation estimation method according to the present invention will be described with reference to the drawings.

[0036] Fig. 1 is a diagram schematically illustrating the environment of an actual propagation path 110, which is a MIMO propagation path between a base station 100, which is an example of a network-side transmitting / receiving device, and an antenna device 10. In Fig. 1, data communication between the base station 100 and the antenna device 10 is performed using multiple subcarriers according to the OFDM modulation method.

[0037] The antenna device 10 is configured to receive the N signals from the base station 100 in an environment of a real propagation path 110 that is configured with a plurality of channels. TxAnt Transmitting antennas Tx#1 to Tx#N TxAnt For example, the antenna device 10 is an air monitor or a UE. The antenna device 10 receives downlink signals transmitted from the transmitting antennas Tx#1 to Tx#N of the base station 100. TxAnt Receive the downlink signal transmitted from N as the received signal. RxAnt Receiving antennas Rx#1 to Rx#N RxAnt and an IQ data output unit 11.

[0038] Here, the transmitting antennas Tx#1 to Tx#N of the base station 100 TxAnt The number of N TxAnt and receiving antennas Rx#1 to Rx#N of the antenna device 10. RxAnt The number of N RxAnt are integers greater than or equal to 2 and greater than or equal to 1, respectively, and N TxAnt ×N RxAnt The value of is the number of channels of the actual propagation path 110.

[0039] The IQ data output unit 11 receives the IQ data from the receiving antennas Rx#1 to Rx#N. RxAnt Received by N RxAntThe received signals are subjected to reception processing such as amplification, frequency conversion, and analog-to-digital conversion. RxAnt The received signals are demodulated to obtain N RxAnt A set of I-component baseband signals and Q-component baseband signals that are orthogonal to each other is generated. In this specification, the I-component baseband signals and Q-component baseband signals are collectively referred to simply as "IQ data."

[0040] h in Figure 1 11 (k,n) ,h 21 (k,n) ,···,h NRxAnt1 (k,n) ,h 12 (k,n) ,h 22 (k,n) ,···,h NRxAnt2 (k,n) ,···,h 1NTxAnt (k,n) ,h 2NTxAnt (k,n) ,···,h NRxAntNTxAnt (k,n) is N shown in equation (4) below. TxAnt ×N RxAnt It is an element of the actual channel matrix H(k,n) in the frequency domain of MIMO.

[0041] As shown in FIG. 2, the test system 1 of this embodiment includes a test device 15, a signal processing unit 20, a simulated propagation path 40, and a display unit 41.

[0042] The test equipment 15 has the function of a pseudo base station device that generates downlink signals required for testing a device under test (DUT) 120, transmits the signals to the DUT 120 via a pseudo propagation path 40, receives uplink signals transmitted from the DUT 120, and performs processing required for the test. The test equipment 15 is configured to test, for example, the demodulation performance of the DUT 120. The pseudo propagation path 40 between the test equipment 15 and the DUT 120 is formed by parameters calculated by a parameter calculation unit 22, which will be described later. The DUT 120 is a UE capable of communication at least in accordance with the MIMO system or the MISO (Multiple Input Single Output) system.

[0043] The signal processing unit 20 includes an actual propagation path estimation characteristics calculation unit 21 , a parameter calculation unit 22 , an actual propagation path channel capacity calculation unit 29 , a pseudo channel capacity calculation unit 30 , and a pseudo propagation path characteristics calculation unit 32 .

[0044] The signal processing unit 20 is configured by a control device such as a computer including, for example, a central processing unit (CPU), a graphics processing unit (GPU), a field programmable gate array (FPGA), a read only memory (ROM), a random access memory (RAM), a hard disk drive (HDD), etc. Furthermore, the signal processing unit 20 can configure at least a part of the actual channel estimation characteristics calculation unit 21, the parameter calculation unit 22, the actual channel channel capacity calculation unit 29, and the pseudo channel capacity calculation unit 30 in software form by executing a predetermined program by the CPU or the GPU.

[0045] The above program may be stored in advance in a ROM or HDD. Alternatively, the program may be provided or distributed in an installable or executable format recorded on a computer-readable recording medium such as a compact disc or DVD. Alternatively, the program may be stored in a computer connected to a network such as the Internet and provided or distributed by downloading via the network.

[0046] The display unit 41 is configured with a display device such as an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube), and displays a setting screen for setting the test contents of the test system 1, test results, calculation results of the transmitting antenna correlation, etc. based on a display control signal from the signal processing unit 20. The display unit 41 may also have operation functions such as soft keys on the display screen.

[0047] The actual propagation path estimation characteristic calculation unit 21 calculates the propagation path characteristic h in the frequency domain of a plurality of channels constituting the actual propagation path 110 by using the RS included in the IQ data output from the IQ data output unit 11 of the antenna device 10. yx (k,n) Estimated characteristics of h^ yx (k,n) The following formula is calculated:

[0048] where h yx (k,n) represents each element of the actual channel matrix H(k,n) of the actual channel 110 in the following equation (4). RxAnt Receiving antennas Rx#1 to Rx#N RxAnt is the index of , which ranges from 1 to R RxAnt x is an integer up to N TxAnt Transmitting antennas Tx#1 to Tx#N TxAnt is the index of TxAnt is an integer up to

[0049] That is, N RxAnt=1 and N TxAnt ≧2 is MISO method, N RxAnt ≧2 and N TxAnt ≧2 indicates MIMO system.

[0050]

number

[0051] In equation (4), k is an index in the frequency axis direction, for example, an index of the subcarrier number. Here, if Δf is the frequency interval of the subcarriers, then the frequency f of each subcarrier is k is k×Δf. Also, n is an index in the time axis direction, for example, an index of an OFDM symbol number. Here, k is an integer from 1 to K, and n is an integer from 1 to N. Also, the propagation path characteristic h yx (k,n) The average power of is assumed to be normalized to 1.

[0052] The RS included in the IQ data output from the IQ data output unit 11 of the antenna device 10 is, for example, in the 5G NR standard, CSI-RS (Channel State Information Reference Signal), DMRS (Demodulation Reference Signal), TRS (Tracking Reference Signal), PTRS (Phase Tracking Reference Signal), etc.

[0053] The actual propagation path estimation characteristic calculation unit 21 calculates the N TxAnt Transmitting antennas Tx#1 to Tx#N TxAnt The known RS included in the downlink signal transmitted from the IQ data output unit 11 and the N RxAnt The propagation path characteristics h yx (k,n) Estimated characteristics of h^ yx (k,n) The estimated characteristic h^ is calculated. yx(k,n) contains information on the amplitude fluctuation amount and phase fluctuation amount of the RS of the IQ data obtained from the received signal received by the y-th receiving antenna Rx#y for a known RS transmitted by the x-th transmitting antenna Tx#x.

[0054] For example, in the case of the 5G NR standard, the actual channel estimation characteristics calculation unit 21 calculates the estimated characteristics ĥ yx (k,n) Used to calculate h^ yx (k,n) represents each element of the matrix H^(k,n) of the estimated values ​​of the actual channel matrix H(k,n) of the actual channel 110 in equation (4), and is expressed as in the following equation (5).

[0055]

number

[0056] The parameter calculation unit 22 calculates the estimated characteristic h^ calculated by the actual propagation path estimation characteristic calculation unit 21. yx (k,n) That is, the parameter calculation unit 22 calculates a parameter that characterizes the statistical properties of the estimated characteristic ĥ calculated by the actual propagation path estimation characteristic calculation unit 21. yx (k,n) Among these, the estimated characteristics h^ during the period in which the statistical properties can be considered unchanged yx (k,n) The parameters calculated by the parameter calculation unit 22 are input to the simulated channel characteristics calculation unit 32 and the simulated channel 40.

[0057] The pseudo channel characteristic calculation unit 32 and the pseudo channel 40 include known channel models such as a TDL model (Tapped Delay Line model) and a CDL model (Clustered Delay Line model). The pseudo channel characteristic calculation unit 32 calculates the frequency characteristics of the pseudo channel 40 according to the parameters of these channel models calculated by the parameter calculation unit 22.

[0058] For example, the parameter calculation unit 22 includes an impulse response calculation unit 23a, a PDP (Power Delay Profile) calculation unit 23b, a K factor calculation unit 24, a transmitting antenna correlation calculation unit 25, a receiving antenna correlation calculation unit 26, a transmitting antenna correlation coefficient estimation unit 27, and a relative phase estimation unit 28, and calculates parameters such as "PDP", "K factor", "transmitting antenna correlation matrix", and "receiving antenna correlation matrix".

[0059] Furthermore, the pseudo propagation path 40 functions as a propagation path simulator formed between the test equipment 15 and the DUT 120 based on the parameters of the channel model calculated by the parameter calculation unit 22 .

[0060] Hereinafter, an example of a calculation method by the parameter calculation unit 22 for the "PDP", "K factor", "transmitting antenna correlation matrix", and "receiving antenna correlation matrix" will be shown, taking the TDL model as an example.

[0061] Estimated characteristic h^ yx (k,n) is a frequency characteristic with k as an index in the frequency axis direction, but multiple delay taps τ mt The impulse response can be expressed as:

[0062] The impulse response calculation unit 23a calculates the estimated characteristic h^ in equation (5). yx (k,n) From the above, the impulse response g of the following equation (6) yx (mt,n)Here, the generalized inverse matrix of matrix A is represented as A+. Mt represents the number of delay taps, and mt is an integer between 1 and Mt. Matrix A is a kind of Fourier transform matrix that can calculate a column vector whose elements are frequency characteristics by multiplying it by a column vector whose elements are time domain impulse responses.

[0063]

number

[0064] The PDP calculation unit 23b calculates the impulse response g calculated by the impulse response calculation unit 23a. yx (mt,n) The PDP, which is a parameter that indicates the power versus delay characteristics of the averaged delay tap, is calculated using the following equation (7): PDP, normalized by the total power and expressed in dB units, is calculated as follows:

[0065]

number

[0066] In equation (7), P tap (mt) is expressed as the following equation (8).

[0067]

number

[0068] However, for the first delay tap, if the scattered wave (None Line Of Sight: NLOS) component is separated from the direct wave (Line Of Sight: LOS) component and the PDP is obtained, the first delay tap P tap (1) is the K factor K calculated by the K factor calculation unit 24 described later. allNLOS It is calculated as shown in the following equation (9).

[0069]

number

[0070] The K factor K shown in this example allNLOS is a parameter that represents the ratio of the power of the LOS to the power of all NLOS. The K factor can be calculated without being affected by precoding, for example, by the method described in the reference document below.

[0071] Specifically, the K factor calculation unit 24 calculates the estimated characteristic ĥ calculated by the actual propagation path estimation characteristic calculation unit 21. yx (k,n) By associating this with "V+v(t)" described in equation (1) of the reference document below, the K factor K can be calculated from equation (9) of the reference document below. allNLOS The following formula is calculated:

[0072] Reference: LJ Greenstein, et al, "Moment-Method Estimation of the Ricean K-Factor," in IEEE Communications Letters, Vol. 3, No. 6, pp. 175-176, June 1999

[0073] The transmitting antenna correlation calculation unit 25 calculates the channel capacity of a known channel model such as a TDL model by multiplying the actual propagation path channel capacity C calculated by an actual propagation path channel capacity calculation unit 29 (to be described later). 1Hz The transmit antenna correlation is calculated so as to be equivalent to (ξ).

[0074] The transmit antenna correlation is determined by the multiple transmit antennas Tx#1 to Tx#N. TxAnt The transmit antenna correlation matrix R indicates the correlation between the propagation path characteristics from txcorr It is defined as an element of (α).

[0075] For example, the transmit antenna correlation matrix R txcorrAs defined in Appendix B of 3GPP (registered trademark) TS38.101-4, (α) can be modeled as a matrix that changes depending on the transmit antenna correlation coefficient α. Here, α is a real number greater than or equal to 0 and less than or equal to 1. The following equations (10a) to (10d) are expressed as a function of the number of transmit antennas N TxAnt The transmit antenna correlation matrix R when txcorr (α).

[0076]

number

[0077] The pseudo channel characteristic calculation unit 32 calculates the K factor K calculated by the K factor calculation unit 24. allNLOS and the transmitting antenna correlation matrix R calculated by the transmitting antenna correlation calculation unit 25. txcorr (α) and the receiving antenna correlation matrix R calculated by the receiving antenna correlation calculation unit 26 described later. rxcorr Based on this, the pseudo-path matrix H sim (α, n) is calculated. When a TDL model is used as the channel model, the pseudo-path matrix H sim (α, n) is expressed as the following equation (11).

[0078]

number

[0079] Here, L in equation (11) rx and L tx (α) is expressed as the following equations (12a) and (12b): where Chol(R) is defined as the Cholesky decomposition of matrix R.

[0080]

number

[0081] L in equation (12a) rx The receive antenna correlation matrix R rxcorr is a signal transmitted from multiple transmitting antennas Tx#1 to Tx#N. TxAnt is the receive antenna correlation matrix that does not include the influence of direct waves of the downlink signal from the rxcorr The calculation method will be described later.

[0082] In equation (12b), when α is 1, L tx (1) is R txcorr Let (α) be a matrix of size such that the elements of the leftmost column are all 1 and the elements of the remaining columns are all 0. This is R txcorr This is because (1) is not a positive definite matrix and cannot be decomposed into Cholesky decomposition.

[0083] H in Eq. (11) iid (n) is a random variable whose elements follow a complex Gaussian distribution with a standard deviation of 1. RxAnt ×N TxAnt is a matrix of size

[0084] OnesRot in Eq. (11) NRxAnt×NTxAnt is expressed as the following equation (13), where the size is N RxAnt ×N TxAnt The magnitude of all elements is 1, and the relative phase of the direct wave is θ R21 (x),θ R31 (x), ,θ RNRxAnt1 Estimated value θ^ of (x) R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 (x) where θ Rab (x) or θ^ Rab (x) is the relative phase or an estimate of the relative phase of the phase of the receiving antenna Rx#a relative to the phase of the direct wave from one transmitting antenna Tx#x at the receiving antenna Rx#b.

[0085]

number

[0086] In addition, analysis in an environment where no LOS components exist (K factor K allNLOS is 0), it is not necessary to use OnesRot in equation (11). NRxAnt×NTxAnt There is no need to calculate the first term including

[0087] Multiple transmit antennas Tx#1 to Tx#N TxAnt The estimated relative phase θ^ between each receiving antenna Rx#y of the direct wave of the downlink signal from R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 (x) is calculated by the relative phase estimation unit 28, which will be described later.

[0088] That is, the pseudo channel matrix H sim The first term of (α,n) is the estimated relative phase of the direct wave, θ^ R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 (x) is the LOS component including the pseudo-path matrix H sim The second term in (α,n) is the estimated relative phase of the direct wave, θ^ R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 (x) is not included in the NLOS components.

[0089] As can be seen from equations (12a) and (12b), the pseudo-path matrix H sim In (α, n), the receiving antenna correlation matrix R rxcorr and the transmit antenna correlation matrix R txcorr (α) is included in the NLOS component.

[0090] As shown in FIG. 3, the receiving antenna correlation calculation unit 26 calculates the correlation between the transmitting antennas Tx#x to N RxAnt Receiving antennas Rx#1 to Rx#N RxAnt Estimated characteristics h^ up to yx (k,n) The elements of the receiving antenna correlation matrix R are the correlations between the receiving antennas. rxcorr The following formula is calculated:

[0091] The effect of precoding on receive antenna correlation can be explained as follows: Unlike transmit antenna correlation, receive antenna correlation can be calculated as defined without being affected by precoding.

[0092] For example, the correlation matrix R including the direct wave effect for the transmitting antenna Tx#x rxcorr_LOS (x) is expressed by the following equation (14).

[0093]

number

[0094] Correlation matrix R rxcorr_LOS The value of the y1 row y2 column component in (x) for k and n is h^ y1x (k,n) and h^ y2x (k,n) The correlation coefficient is calculated as the correlation coefficient between h^ and y1x (k,n) and h^ y2x (k,n) It depends on the relative phase between

[0095]

number

[0096] Here, the relative phase in equation (15) is the phase ∠h^ due to precoding. y1x(prc) (k,n) ,∠h^ y2x(prc) (k,n) and the phase ∠h^ due to the actual propagation path 110 y1x(ch) (k,n) ,∠h^ y2x(ch) (k,n) where one or more receiving antennas Rx#1 to Rx#N RxAnt Since the transmit antenna Tx#x is common to all, the phase ∠h^ due to precoding in equation (15) y1x(prc) (k,n) and ∠h^y2x(prc) (k,n) is cancelled out.

[0097] Therefore, the correlation matrix R rxcorr_LOS The y1 row, y2 column component of (x) is expressed as in the following equation (16).

[0098]

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[0099] As can be seen from the above equation (16), the receive antenna correlation is the phase ∠h^ due to precoding. y1x(prc) (k,n) ,∠h^ y2x(prc) (k,n) can be calculated directly without being affected by

[0100] The relative phase estimation unit 28 calculates the correlation matrix R rxcorr_LOS (x) and the pseudo-path matrix H sim Relative phase θ of the direct wave included in (α, n) R21 (x),θ R31 (x), ,θ RNRxAnt1 Estimated value θ^ of (x) R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 (x) is calculated.

[0101] Hereinafter, the relative phase estimation unit 28 estimates the relative phase of the direct wave, θ^ R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 The procedure for calculating (x) will be explained below.

[0102] For each transmitting antenna Tx#x, the function f RLosPh (x) where |z| denotes the magnitude of the complex number z, and f RLosPh (x) is a positive real number.

[0103]

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[0104] The relative phase estimation unit 28 estimates the relative phase θ̂ R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 As a method for calculating (x), for example, one of the following two methods can be considered.

[0105] [Method 1 for calculating relative phase estimates] The relative phase estimation unit 28 uses the steepest descent method to numerically calculate f RLosPh The relative phase θ that maximizes (x) R21 (x),θ R31 (x), ,θ RNRxAnt1 (x) is calculated using the following equations (18a), (18b), and (18c).

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[0107] The parameter η in equations (18a), (18b), and (18c) is the relative phase θ R21 (x),θ R31 (x), ,θ RNRxAnt1 It is desirable to set an appropriate value based on the speed and stability of convergence of (x).

[0108] First, the relative phase estimation unit 28 calculates the relative phase θ R21 (x),θ R31 (x), ,θ RNRxAnt1 Determine the initial value of (x). For example, the initial value of all relative phases may be zero.

[0109] Next, the relative phase estimation unit 28 calculates the relative phase θ R21 (x),θ R31 (x), ,θ RNRxAnt1 (x) is updated by equations (18a), (18b), and (18c), respectively, where partial differentiation is performed using numerical differentiation.

[0110] Next, the relative phase estimation unit 28 performs the calculations of equations (18a), (18b), and (18c) for each relative phase θ R21 (x),θ R31 (x), ,θ RNRxAnt1 Repeat this process until the update of (x) becomes small enough, and use the converged relative phase as the estimated value of the relative phase θ^ R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 Let (x).

[0111] [Method 2 for calculating relative phase estimates] The relative phase estimation unit 28 estimates the relative phase θ̂ R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 (x) is calculated approximately as follows:

[0112] The relative phase estimation unit 28 calculates the correlation matrix R rxcorr_LOS The eigenvector u (bold) corresponding to the largest eigenvalue obtained by eigenvalue decomposition of (x) is used to estimate the relative phase θ^ R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 (x) is calculated as shown in equations (19a), (19b), (19c), and (19d) below.

[0113]

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[0114] However, equation (19d) is f RLosPh This is an approximation that assumes that the magnitude of each element of the eigenvector u (bold) that maximizes (x) is equal, and κ is a real constant.

[0115] By using Method 2, it is possible to calculate approximate values ​​to a certain extent while reducing the calculation load compared to Method 1.

[0116] Below, f RLosPh The relative phase θ that maximizes (x) R21 (x),θR31 (x), ,θ RNRxAnt1 (x) is the estimated relative phase of the direct wave θ^ R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 Provide additional explanation as to why (x) is appropriate.

[0117] The channel matrix H(n) of the MIMO channel including the direct wave and the scattered wave can be expressed as the following equation (20), similarly to equation (11).

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[0119] Correlation matrix R including the influence of direct waves rxcorr_LOS (x) is the column vector v (bold) consisting of the x-th column element of H(n) in equation (20). RLosPh0 (x) is used to calculate the following equation (21).

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[0121] Here, h (bold) iid (n) is H iid It is a column vector consisting of the x-th column elements of (n).

[0122] When N>>1, the approximation shown in the following equation (22) holds.

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[0124] f in equation (17) RLosPh (x) is transformed into the following equation (23) using equation (22).

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[0126] The relative phase that maximizes the first term in the absolute value of equation (23) is the relative phase θ of the direct wave. R21 (x),θ R31 (x), ,θ RNRxAnt1 (x) itself. In other words, considering that the statistical average of the second term in the absolute value of equation (23) is likely to be near zero, f RLosPh The relative phase θ that maximizes (x) R21 (x),θ R31 (x), ,θ RNRxAnt1 (x) is the estimated relative phase of the direct wave θ^ R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 It turns out that (x) is a good approximation.

[0127] Hereinafter, the receiving antenna correlation calculation unit 26 calculates the K factor calculated by the K factor calculation unit 24 and the estimated value θ^ of the relative phase calculated by the relative phase estimation unit 28. R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 (x), the correlation matrix R for each transmit antenna Tx#x is calculated. rxcorr_LOS Correlation matrix R, which removes the influence of direct waves from (x) rxcorr_NLOS The procedure for calculating (x) will be explained below.

[0128] First, the receiving antenna correlation calculation unit 26 calculates a correlation matrix R in which the phases of the direct waves are all adjusted so that they are all zero (in the real axis direction on the complex plane), as shown in the following equation (24). rxcorr_LOSadj (x) where diag(v(bold)^ in equation (24) RLosPh (x)) is a column vector v (bold)^ RLosPh This is an operator that indicates a diagonal matrix with the elements of (x) as diagonal components. Also, v (bold)^ RLosPh (x) * is a column vector v(bold)^ RLosPh It is a column vector obtained by taking the conjugate of each element of (x).

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[0130] Next, the receiving antenna correlation calculation unit 26 calculates a correlation matrix R , which excludes the influence of the direct wave, as shown in the following equation (25). rxcorr_NLOS (x) is calculated. However, in equation (25), NRxAnt×NRxAnt is size N RxAnt ×N RxAnt is a matrix where all elements are 1.

[0131]

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[0132] The validity of equation (25) will be explained below.

[0133] The receiving antenna correlation of the NLOS signal (scattered wave signal) for two channels from a common transmitting antenna Tx#x to receiving antennas Rx#i and Rx#j is ρ ij Then, the propagation path characteristics of the two channels are given by K factor K allNLOS can be written as the following equations (26a) and (26b), respectively.

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[0135] In formulas (26a) and (26b), f SCS is the sampling interval along the frequency axis, τ LOS is the propagation delay time of the LOS component. i (k,n) and n j (k,n) are random variables that are uncorrelated and have a complex Gaussian distribution with a standard deviation of 1.

[0136] In this case, the correlation matrix R for each transmitting antenna Tx#x is rxcorr_LOSThe i-th row and j-th column component of (x) is expressed by the following equation (27): Note that in equation (27), the number of samples used for the average is assumed to be sufficiently large to eliminate statistical errors.

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[0138] In equation (27), <x (k,n) Notation like > is x (k,n) represents the average over a sufficiently large number of samples (average over subcarrier number k and OFDM symbol number n).

[0139] One or more receiving antennas Rx#1 to Rx#N RxAnt Assuming that the relative phases of the direct waves in can be accurately estimated, the correlation matrix R is obtained by adjusting the phase so that all the phases of the direct waves are zero. rxcorr_LOSadj The component r^ of the i-th row and j-th column of (x) Rij is expressed as the following equation (28).

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[0141] However, in equation (28), the correlation matrix R rxcorr_NLOS The i-th row and j-th column component of (x) is r Rij It is written as follows.

[0142] Equation (28) can be rewritten as the following equation (29).

[0143]

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[0144] If we summarize all elements of the i-th row and j-th column components of equation (29), we get R rxcorr_NLOS (x) is obtained.

[0145] The receiving antenna correlation calculation unit 26 calculates the correlation matrix R rxcorr_NLOS (x) for all transmitting antennas Tx#x, the receiving antenna correlation matrix R rxcorr Calculate.

[0146]

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[0147] The receiving antenna correlation matrix R calculated by equation (30) rxcorr is the correlation matrix that does not include the influence of the direct wave, and L in equation (11) rx In addition, analysis in an environment where no LOS components exist (K factor K allNLOS becomes 0), the correlation matrix R rxcorr_NLOS (x) is the correlation matrix R before eliminating the influence of the direct wave rxcorr_LOS It can also be replaced with (x).

[0148] The actual propagation path channel capacity calculation unit 29 calculates the estimated characteristic h^ calculated by the actual propagation path estimation characteristic calculation unit 21. yx (k,n) The channel capacity C0 [bit / sec / Hz] of the actual propagation path 110 is calculated from the above equation. Here, the channel capacity C0 is the channel capacity at each (k, n) to which the RS is allocated. The channel capacity is the theoretical upper limit of throughput, and can be said to be an index indicating how easily throughput can be achieved. The throughput is determined by the modulation method, the error correction method, the amount of wireless resource allocation, etc.

[0149] Under the condition that base station 100 does not use CSI, channel capacity C0 is calculated by the following equation (31).

[0150]

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[0151] Here, ξ is the SNR (Signal-to-Noise Ratio) (linear value) for each receiving antenna Rx#y. i (k,n) is H^(k,n)H^(k,n) H is the i-th eigenvalue of , where index i ranges from 1 to N TxAnt and N RxAnt The smaller of H^(k,n) H is the conjugate transpose of the matrix H^(k,n) of the estimated characteristics of the actual channel matrix.

[0152] Furthermore, the actual propagation path channel capacity calculation unit 29 calculates the actual propagation path channel capacity C 0 , which is the average of the channel capacity C 0 of the actual propagation path 110 in a bandwidth where the number of subcarriers is K and the number of OFDM symbols is N. 1Hz (ξ) [bit / sec / Hz] is calculated according to the following equation (32).

[0153]

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[0154] The pseudo channel capacity calculation unit 30 calculates the pseudo channel matrix H calculated by the pseudo channel characteristic calculation unit 32 as follows: sim From (α, n), the pseudo channel capacity C of the channel model is calculated. Sim1Hz (ξ,α) is calculated.

[0155] Here, the pseudo channel matrix H obtained by equation (11) sim For (α,n), H sim (α,n)H sim (α,n) H When the eigenvalue decomposition is performed, the eigenvalue is λ p sim(α,n) Let the index p be from 1 to N TxAnt and N RxAnt The value is up to the smaller of

[0156] At this time, the pseudo channel capacity calculation unit 30 calculates N=N sym Pseudo channel matrix H simUsing (α,n), the pseudo-path matrix H sim The pseudo channel capacity C, which is the average of the channel capacities of (α, n), Sim1Hz (ξ, α) is calculated as shown in the following equation (33). sym The specific value of needs to be adjusted by considering the balance between processing time and the variation in results. For example, N sym =1000.

[0157]

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[0158] The transmitting antenna correlation coefficient estimator 27 estimates the actual propagation path channel capacity C calculated by the actual propagation path channel capacity calculator 29. 1Hz (ξ) and the pseudo channel capacity C calculated by the pseudo channel capacity calculation unit 30 Sim1Hz The transmitting antenna correlation coefficient α is estimated so that the difference from (ξ, α) is smaller than a specified value.

[0159] For example, when ξ=1000 (i.e., SNR is 30 dB), the transmission antenna correlation coefficient estimation unit 27 estimates the pseudo channel capacity C Sim1Hz (ξ,α) is the actual channel capacity C 1Hz (ξ) is approximately equal to the actual channel capacity C 1Hz (ξ) is the pseudo-channel capacity C of the channel model Sim1Hz This is the target value when adjusting (ξ, α).

[0160] The transmitting antenna correlation calculation unit 25 calculates the transmitting antenna correlation coefficient α estimated by the transmitting antenna correlation coefficient estimation unit 27 and converts it into a transmitting antenna correlation matrix R txcorr By substituting into (α), multiple transmitting antennas Tx#1 to Tx#N TxAnt Estimated characteristics h^ from each receiving antenna Rx#y yx (k,n) The transmit antenna correlation matrix R txcorr It is calculated using (α).

[0161] An example of specific processing by the transmitting antenna correlation coefficient estimator 27, the pseudo channel capacity calculator 30, and the pseudo propagation path characteristics calculator 32 will be described below with reference to the graphs in Figures 4, 5(a) and 5(b), and the flowchart in Figure 6. Note that descriptions that overlap with the description of the configuration of the test system 1 described above will be omitted as appropriate.

[0162] As shown in Figure 4, the pseudo channel capacity C Sim1Hz Among the values ​​of α in (ξ,α), the value used in the following process is α m , α m―1(max) , and α m―1(min) (m is an integer equal to or greater than 1 and is an index that counts the number of repetitions). In addition, when narrowing down the range of α and the corresponding range of channel capacity through repetitive processing, α = α m―1(max) C when Sim1Hz (ξ,α m―1(max) ) is the upper limit of the channel capacity C max corresponds to α=α m―1(min) C when Sim1Hz (ξ,α m―1(min) ) is the lower limit of the channel capacity C min It corresponds to C Sim1Hz Since (ξ,α) is considered to be a monotonically decreasing function of α, α m―1(max) ≦α m―1(min) is.

[0163] As shown in FIG. 6, first, the transmitting antenna correlation coefficient estimator 27 sets the initial value of the index m to 1, and sets the value of ξ to, for example, 1000 (step S1).

[0164] Next, the transmitting antenna correlation coefficient estimation unit 27 calculates α m―1(max) =α 0(max) The value is set to 0 (step S2).

[0165] Next, the pseudo channel characteristic calculation unit 32 calculates N sym Pseudo channel matrix H sim The pseudo channel capacity calculation unit 30 calculates N (0, n). symPseudo channel matrix H sim Using (0,n), the pseudo channel capacity C Sim1Hz (ξ, 0) is calculated (step S3).

[0166] Next, the transmitting antenna correlation coefficient estimation unit 27 calculates C max The value of C Sim1Hz Set it to (ξ, 0) (step S4).

[0167] Next, the transmitting antenna correlation coefficient estimation unit 27 calculates α m―1(min) =α 0(min) The value is set to 1 (step S5).

[0168] Next, the pseudo channel characteristic calculation unit 32 calculates N sym Pseudo channel matrix H sim The pseudo channel capacity calculation unit 30 calculates N sym Pseudo channel matrix H sim Using (1,n), the pseudo channel capacity C Sim1Hz (ξ, 1) is calculated (step S6).

[0169] Next, the transmitting antenna correlation coefficient estimation unit 27 calculates C min The value of C Sim1Hz Set it to (ξ, 1) (step S7).

[0170] The actual channel capacity C, which is the target channel capacity 1Hz (ξ) is C min Above and C max If it is equal to or less than that (step S8: YES), the process of step S12 is executed.

[0171] Target C 1Hz (ξ) is C min Above and C max Not the following (Step S8: NO), but the target C 1Hz (ξ) is C max If it is greater than (step S9: YES), the transmitting antenna correlation coefficient estimation unit 27 changes the value of α1 to α 0(max)= 0 (step S10). Then, the process of step S19 is executed.

[0172] On the other hand, the target C 1Hz (ξ) is C min (step S9: NO), the transmitting antenna correlation coefficient estimation unit 27 changes the value of α1 to α 0(min) = 1 (step S11). Then, the process of step S19 is executed.

[0173] In step S12, the transmitting antenna correlation coefficient estimation unit 27 calculates the C of the target by the following equation (34): 1Hz α corresponding to (ξ) m (Step S12). Equation (34) is expressed as C Sim1Hz (ξ,α) is α m―1(max) From α m―1(min) is a linear function of α in the range of m is an equation to estimate

[0174]

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[0175] Next, the pseudo channel characteristic calculation unit 32 calculates α obtained by equation (34) m N corresponding to sym Pseudo channel matrix H sim (α m , n). The pseudo channel capacity calculation unit 30 calculates N sym Pseudo channel matrix H sim (α m , n) to calculate the pseudo channel capacity C Sim1Hz (ξ,α m ) is calculated (step S13).

[0176] C Sim1Hz (ξ,α m ) and the target C 1Hz Absolute value of percentage error of (ξ) Err ChCapIf the absolute value of the percentage error Err is equal to or less than the specified value (for example, 1%) (step S14: YES), the process of step S19 is executed. ChCap is calculated by the following formula (35). On the other hand, the absolute value of the percentage error, Err ChCap If is greater than the specified value (step S14: NO), the process proceeds to step S15.

[0177]

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[0178] C Sim1Hz (ξ,α m ) is C 1Hz If it is greater than (ξ) (step S15: YES), the transmitting antenna correlation coefficient estimation unit 27 calculates C max The value of C Sim1Hz (ξ,α m ) to α m(max) The value of α m To, α m(min) The value of α m―1(min) (step S16).

[0179] C Sim1Hz (ξ,α m ) is C 1Hz If it is smaller than (ξ) (step S15: NO), the transmitting antenna correlation coefficient estimation unit 27 calculates C min The value of C Sim1Hz (ξ,α m ) and α m(min) The value of α m To, α m(max) The value of α m―1(max) (step S17).

[0180] Next, the transmitting antenna correlation coefficient estimation unit 27 increments the current value of the index m by 1 (step S18), and then the processes from step S12 onwards are executed again.

[0181] In step S19, the transmitting antenna correlation coefficient estimation unit 27 calculates the current α mThe value of is output to the transmitting antenna correlation calculation unit 25 (step S19).

[0182] In this way, the transmitting antenna correlation coefficient estimator 27 calculates α m―1(max) From α m―1(min) Gradually narrow the range of α m Calculate the value of the actual channel capacity C 1Hz Pseudo channel capacity C close to (ξ) Sim1Hz Determine α for which (ξ,α) is obtained.

[0183] Note that steps S3, S6, and S13 are performed using the K factor K allNLOS and the transmit antenna correlation matrix R txcorr (α) and the receiving antenna correlation matrix R rxcorr Based on this, the pseudo-path matrix H of the channel model is sim (α m , n), and a pseudo channel characteristic calculation step for calculating the pseudo channel matrix H sim (α m ,n) to obtain the pseudo channel capacity C of the channel model Sim1Hz A pseudo channel capacity calculation step for calculating (ξ, α) is configured.

[0184] The pseudo propagation path characteristic calculation step is to estimate the relative phase of the direct wave θ^ R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 The estimated relative phase of the LOS component (x) and the direct wave θ^ R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 The pseudo-path matrix H consisting of the sum of NLOS components that do not include (x) sim Calculate (α, n).

[0185] An example of the process of a transmitting antenna correlation estimation method using the test system 1 of this embodiment will be described below with reference to the flowchart in Fig. 7. Note that descriptions that overlap with the description of the configuration of the test system 1 described above will be omitted as appropriate.

[0186] First, the IQ data of the downlink signal is input from the IQ data output unit 11 of the antenna device 10 to the signal processing unit 20 (step S21).

[0187] Next, the actual propagation path estimation characteristic calculation unit 21 calculates the propagation path characteristics h of the multiple channels that make up the actual propagation path 110 using the RS included in the IQ data input in step S21. yx (k,n) Estimated characteristics of h^ yx (k,n) is calculated (actual propagation path estimation characteristic calculation step S22).

[0188] Next, the actual propagation path channel capacity calculation unit 29 calculates the estimated characteristic h^ calculated by the actual propagation path estimation characteristic calculation unit 21. yx (k,n) From this, the actual channel capacity C of the actual channel 110 1Hz (ξ) is calculated (actual propagation path channel capacity calculation step S23).

[0189] Next, the K factor calculation unit 24 calculates the estimated characteristic h^ calculated by the actual propagation path estimation characteristic calculation unit 21. yx (k,n) From K factor K allNLOS is calculated (K factor calculation step S24).

[0190] Next, the relative phase estimation unit 28 estimates the phases of the multiple transmitting antennas Tx#1 to Tx#N TxAnt The estimated relative phase θ^ between each receiving antenna Rx#y of the direct wave of the downlink signal from R21 (x),θ^ R31 (x),···,θ^ RNRxAnt1 (x) is calculated (relative phase estimation step S25).

[0191] Next, the receiving antenna correlation calculation unit 26 calculates the correlation between each transmitting antenna Tx#x and one or more receiving antennas Rx#1 to Rx#N. RxAnt Estimated characteristics h^ up to yx (k,n) The receive antenna correlation matrix R indicates the receive antenna correlation, which is the correlation between rxcorr is calculated (receiving antenna correlation calculation step S26).

[0192] Next, the transmitting antenna correlation coefficient estimator 27, the pseudo channel capacity calculator 30, and the pseudo propagation path characteristic calculator 32 calculate the actual propagation path channel capacity C 1Hz (ξ) and the pseudo-channel capacity C Sim1Hz A transmitting antenna correlation coefficient α is estimated such that the difference from (ξ, α) is smaller than a specified value (transmitting antenna correlation coefficient estimation step S27).

[0193] Next, the transmitting antenna correlation calculation unit 25 calculates the transmitting antenna correlation coefficient α estimated by the transmitting antenna correlation coefficient estimation unit 27. m The transmit antenna correlation matrix R txcorr (α m ) and multiple transmit antennas Tx#1 to Tx#N TxAnt Estimated characteristics h^ from each receiving antenna Rx#y yx (k,n) The transmitting antenna correlation, which is the correlation between the two antennas, is calculated (transmitting antenna correlation calculation step S28).

[0194] Next, the signal processing unit 20 calculates the transmitting antenna correlation matrix R calculated by the transmitting antenna correlation calculation unit 25. txcorr (α m ) is displayed on the display unit 41 (step S29).

[0195] As described above, the test system 1 according to this embodiment calculates the actual channel capacity calculated based on the RS included in the IQ data of the downlink signal propagating from the actual base station 100 to the antenna device 10, and the pseudo channel capacity C Sim1Hz The transmit antenna correlation is calculated so that (ξ, α) are equivalent.

[0196] As a result, the test system 1 according to this embodiment can analyze RSs such as precoded DMRSs and estimate transmit antenna correlation with high accuracy.

[0197] When performing a throughput test using a channel model, it is sometimes required to obtain a value close to the throughput achieved in an actual MIMO propagation path environment. Since the channel capacity is the theoretically achievable throughput, it can be said that a propagation path with the same channel capacity is a propagation path that can obtain the same throughput. Therefore, by using the test system 1 according to this embodiment, it becomes possible to perform a throughput test of the DUT 120 using a channel model that can obtain a throughput equivalent to that of an actual MIMO propagation path.

[0198] The test system 1 according to this embodiment also includes a plurality of transmitting antennas Tx#1 to Tx#N. TxAnt The relative phase θ between each receiving antenna Rx#y of the direct wave of the downlink signal from R21 (x),θ R31 (x), ,θ RNRxAnt1 Based on the pseudo propagation path characteristics consisting of the sum of the LOS component containing information on (x) and the NLOS component which does not contain information on the relative phase of the direct wave, the pseudo channel capacity C Sim1Hz (ξ,α) is calculated.

[0199] As a result, the test system 1 according to this embodiment can obtain a pseudo channel capacity C that reflects the phase relationship of the LOS components in the same way as the phase relationship of the actual IQ data. Sim1Hz (ξ,α) can be calculated.

[0200] Furthermore, the test system 1 according to this embodiment can test the DUT 120 by reproducing the statistical channel characteristics of the actual channel 110 using the simulated channel characteristics.

[0201] In the present embodiment described above, the base station 100 is the network-side transceiver that transmits the downlink signal toward the actual propagation path 110. However, instead of a base station, the network-side transceiver may be, for example, a Wi-Fi (registered trademark) access point. [Explanation of symbols]

[0202] 1 Test System 10 Antenna device 11 IQ data output section 15 Test equipment 20 Signal Processing Section 21 Actual propagation path estimation characteristic calculation unit 22 Parameter calculation section 24 K factor calculation section 25 Transmitting antenna correlation calculation unit 26 Receiving antenna correlation calculation unit 27 Transmitting antenna correlation coefficient estimation unit 28 Relative phase estimation unit 29 Actual propagation path channel capacity calculation unit 30 Pseudo channel capacity calculation unit 32 Pseudo propagation path characteristic calculation unit 40 Pseudo propagation path 41 Display section 100 Base station (network side transmitting / receiving device) 110 Actual propagation path 120 DUT Rx#1~Rx#N RxAnt Receiving antenna Tx#1~Tx#N TxAnt Transmitting antenna

Claims

1. A network-side transceiver (100) has a plurality of transmitting antennas (Tx#1 to Tx#N ＴｘＡｎｔ ) is transmitted to one or more receiving antennas (Rx#1 to Rx#N) in the environment of the actual propagation path (110). ＲｘＡｎｔ an actual propagation path estimation characteristic calculation unit (21) that calculates an estimation characteristic of the propagation path characteristic of the actual propagation path using a reference signal included in IQ data of the downlink signal output from an antenna device (10) that receives the downlink signal; an actual propagation path channel capacity calculation unit (29) that calculates an actual propagation path channel capacity of the actual propagation path from the estimated characteristics; a K factor calculation unit (24) that calculates a K factor from the estimated characteristics; a receiving antenna correlation calculation unit (26) that calculates a receiving antenna correlation that is a correlation between the estimated characteristics from each of the transmitting antennas to the one or more receiving antennas; a transmitting antenna correlation calculation unit (25) that calculates a transmitting antenna correlation, which is a correlation between the estimated characteristics from the plurality of transmitting antennas to each of the receiving antennas, using a transmitting antenna correlation matrix that changes according to a transmitting antenna correlation coefficient; a pseudo propagation path characteristic calculation unit (32) that calculates pseudo propagation path characteristics of a channel model based on the K factor, the transmitting antenna correlation, and the receiving antenna correlation; a pseudo channel capacity calculation unit (30) for calculating a pseudo channel capacity of the channel model from the pseudo propagation path characteristics; a transmitting antenna correlation coefficient estimating unit (27) for estimating the transmitting antenna correlation coefficient such that a difference between the actual propagation path channel capacity and the pseudo channel capacity is smaller than a specified value, a transmitting antenna correlation calculation unit that calculates the transmitting antenna correlation by substituting the transmitting antenna correlation coefficient estimated by the transmitting antenna correlation coefficient estimation unit into the transmitting antenna correlation matrix.

2. a relative phase estimator (28) that calculates an estimated value of a relative phase between each of the receiving antennas of direct waves of the downlink signals from the plurality of transmitting antennas; 2. The test system according to claim 1, wherein the pseudo-path characteristic calculation unit calculates the pseudo-path characteristic consisting of a sum of a direct wave component including an estimated value of the relative phase of the direct wave and a scattered wave component not including an estimated value of the relative phase of the direct wave.

3. 3. The test system according to claim 2, wherein the receiving antenna correlation calculation unit calculates the receiving antenna correlation so as to eliminate the influence of a direct wave component including the estimated value of the relative phase of the direct wave.

4. 4. The test system according to claim 3, wherein the scattered wave components include the receiving antenna correlation and the transmitting antenna correlation in the pseudo propagation path characteristics.

5. A network-side transceiver (100) has a plurality of transmitting antennas (Tx#1 to Tx#N ＴｘＡｎｔ ) is transmitted to one or more receiving antennas (Rx#1 to Rx#N) in the environment of the actual propagation path (110). ＲｘＡｎｔ an actual propagation path estimation characteristic calculation step (S22) of calculating an estimated characteristic of the propagation path characteristic of the actual propagation path using a reference signal included in the IQ data of the downlink signal output from the antenna device (10) receiving the downlink signal; an actual propagation path channel capacity calculation step (S23) of calculating an actual propagation path channel capacity of the actual propagation path from the estimated characteristics; a K factor calculation step (S24) of calculating a K factor from the estimated characteristics; a receiving antenna correlation calculation step (S26) of calculating a receiving antenna correlation which is a correlation between the estimated characteristics from each of the transmitting antennas to the one or more receiving antennas; a transmitting antenna correlation calculation step (S28) of calculating a transmitting antenna correlation, which is a correlation between the estimated characteristics from the plurality of transmitting antennas to each of the receiving antennas, using a transmitting antenna correlation matrix that changes according to a transmitting antenna correlation coefficient; a pseudo propagation path characteristic calculation step (S3, S6, S13) of calculating a pseudo propagation path characteristic of a channel model based on the K factor, the transmitting antenna correlation, and the receiving antenna correlation; a pseudo channel capacity calculation step (S3, S6, S13) of calculating a pseudo channel capacity of the channel model from the pseudo channel characteristics; a transmitting antenna correlation coefficient estimating step (S27) of estimating the transmitting antenna correlation coefficient such that a difference between the actual propagation path channel capacity and the pseudo channel capacity is smaller than a specified value; a transmitting antenna correlation calculation step of calculating the transmitting antenna correlation by substituting the transmitting antenna correlation coefficient estimated in the transmitting antenna correlation coefficient estimation step into the transmitting antenna correlation matrix;

6. a relative phase estimation step (S25) of calculating an estimated value of a relative phase between each of the receiving antennas of the direct waves of the downlink signals from the plurality of transmitting antennas, 6. The transmitting antenna correlation estimation method according to claim 5, wherein the pseudo-path characteristic calculation step calculates the pseudo-path characteristic comprising a sum of a direct wave component including the estimated value of the relative phase of the direct wave and a scattered wave component not including the estimated value of the relative phase of the direct wave.

7. 7. The transmitting antenna correlation estimation method according to claim 6, wherein the receiving antenna correlation calculation step calculates the receiving antenna correlation so as to eliminate the influence of a direct wave component including the estimated value of the relative phase of the direct wave.

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