Test system and method for estimating correlation between transmitting antennas

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 the correlation between transmitting antennas. [Background technology]

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

[0003] Generally, a known method for simulating actual propagation path environments is to reconstruct the propagation path characteristics themselves, as measured in the actual propagation path environment.

[0004] The ACE RNX Channel Emulator's "Field-to-Lab" (see, for example, Non-Patent Document 1) collects data of downlink signals transmitted by a real base station as they travel along the actual propagation path, analyzes this data to extract the propagation path characteristics of the actual propagation path, and then reproduces the instantaneous values ​​of the propagation path characteristics of the actual propagation path to test the demodulation section of the UE. By reproducing the actual propagation path characteristics as they are, the "Field-to-Lab" can faithfully reproduce the actual propagation path characteristics.

[0005] However, the existing "Field-to-Lab" method disclosed in Non-Patent Document 1 reproduces the actual propagation path characteristics as they are, meaning the test time for the UE is determined by the data acquisition time. Furthermore, since the antenna used for data acquisition is different from the actual UE antenna, there is little significance in reproducing the instantaneous values ​​of the propagation path characteristics themselves.

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

[0007] [Non-Patent Document 1] "ACE RNX Channel Emulator" product catalog, March 1, 2018 [Overview of the project] [Problems that the invention aims to solve]

[0008] Transmit antenna correlation is one of the parameters of a channel model. However, when calculating the parameters of a channel model using channels that are precoded at the base station's transmitting section, such as the DMRS (Demodulation Reference Signal) of PDSCHs, which are mainly data channels, 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 PDSCH as a downlink signal, DMRS is transmitted along with user data, as shown in Figure 8. At this time, the user data and DMRS are pre-coded for each layer by the precoder 130. In other words, since the pre-coding is integrated with the propagation path characteristics, it is not possible to distinguish between the propagation path characteristics and the pre-coding from the signal received by the air monitor 10b, etc.

[0010] For example, as shown in Figure 8, different precoding matrices may be applied to each subband on the frequency axis or to each symbol on the time axis. Since the relative phase between the transmitting antennas of base station 100 depends on the precoding matrix, 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 when attempting to directly calculate the transmitting antenna correlation according to the definition.

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

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

[0013]

number

[0014] In Equation (1), k is an index in the frequency axis direction, for example, an index of the subcarrier number. Also, n is an index in the time axis direction, for example, an index of the 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

[0018] , (k,n) , , (k,n) , , (k,n) ,

[0020] , (k,n) , , , , , , yx2(ch) , , yx1(ch) , ,

[0019] , yx2(prc) , (k,n) is assumed to be normalized to 1 in average power.

[0015] For a certain k and n of the x1-row x2-column component in the above transmission antenna correlation matrix, the value is yx1 (k,n) calculated as the correlation coefficient between h yx2 (k,n) and h yx1 (k,n) That correlation coefficient depends on the relative phase between h yx2 (k,n) and h

[0016]

Equation

[0017] Here, the relative phase in Equation (2) includes the phase ∠h yx1(prc) (k,n) , ∠h[[ID=3S]] yx2(prc) (k,n) due to precoding and the phase ∠h yx1(ch) (k,n) [[ID=SO]]due to the MIMO propagation path ∠h yx2(ch) (k,n)

[0018] Therefore, the x1-row x2-column component of the transmission antenna correlation matrix is expressed as in the following Equation (3).

[0019]

Equation

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

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

[0022] To solve the above problems, the test system according to the present invention comprises multiple transmitting antennas (Tx#1~Tx#N) of the network-side transceiver (100). TxAnt A downlink signal transmitted from ) is received in the environment of the actual propagation path (110) by one or more receiving antennas (Rx#1~Rx#N RxAnt A real propagation path estimation characteristic calculation unit (21) calculates estimated characteristics of the propagation path characteristics of the actual propagation path using a reference signal included in the IQ data of the downlink signal output from the antenna device (10) that receives the signal, a real propagation path channel capacity calculation unit (29) calculates the actual propagation path channel capacity of the actual propagation path from the estimated characteristics, a K factor calculation unit (24) calculates the K factor from the estimated characteristics, and a receiving antenna correlation calculation unit (26) calculates the receiving antenna correlation, which is the correlation between the estimated characteristics from each of the transmitting antennas to the one or more receiving antennas. ,before The K factor and, This is the correlation between the estimated characteristics from the plurality of transmitting antennas to each of the receiving antennas. A pseudo-propagation path characteristic calculation unit (32) calculates pseudo-propagation path characteristics of the channel model based on the transmitting antenna correlation and the receiving antenna correlation; a pseudo-channel capacity calculation unit (30) calculates the pseudo-channel capacity of the channel model from the pseudo-propagation path characteristics; and the difference between the actual propagation path channel capacity and the pseudo-channel capacity. Based on,A transmitting antenna correlation coefficient estimation unit (27) estimates the transmitting antenna correlation coefficient, A transmitting antenna correlation calculation unit (25) 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, Includes, The pseudo-channel capacity calculation unit first calculates the pseudo-channel capacity based on the initial value of the transmitting antenna correlation coefficient. The processing of the transmitting antenna correlation coefficient estimation unit, the transmitting antenna correlation calculation unit, the pseudo-propagation path characteristic calculation unit, and the pseudo-channel capacity calculation unit is repeated until the difference between the actual propagation path channel capacity and the pseudo-channel capacity becomes smaller than a specified value. The transmitting antenna correlation calculation unit then uses the transmitting antenna correlation coefficient when the difference between the actual propagation path channel capacity and the pseudo-channel capacity becomes smaller than the specified value to calculate the final transmitting antenna correlation. It is structured.

[0023] With this configuration, the test system according to the present invention calculates the transmitting antenna correlation such 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 precoded RS signals such as DMRS and accurately estimate the transmitting antenna correlation.

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

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

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

[0028] With this configuration, the test system according to the present invention can calculate a pseudo-channel capacitance that reflects the phase relationship of the direct wave component, similar to the phase relationship of 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 in a manner that eliminates the influence of the direct wave component, including the estimated value of the relative phase of the direct wave.

[0030] Furthermore, the transmitting antenna correlation estimation method according to the present invention involves multiple transmitting antennas (Tx#1~Tx#N) of the network-side transmitting and receiving device (100). TxAnt A downlink signal transmitted from ) is received in the environment of the actual propagation path (110) by one or more receiving antennas (Rx#1~Rx#N RxAnt A real propagation path estimation characteristic calculation step (S22) calculates estimated characteristics of the propagation path characteristics of the actual propagation path using a reference signal included in the IQ data of the downlink signal output from the antenna device (10) that receives the signal, a real propagation path channel capacity calculation step (S23) calculates the actual propagation path channel capacity of the actual propagation path from the estimated characteristics, a K factor calculation step (S24) calculates the K factor from the estimated characteristics, and a receiving antenna correlation calculation step (S26) calculates the receiving antenna correlation, which is the correlation between the estimated characteristics from each of the transmitting antennas to the one or more receiving antennas. ,before The K factor and, This is the correlation between the estimated characteristics from the plurality of transmitting antennas to each of the receiving antennas. A pseudo-propagation path characteristic calculation step (S3, S6, S13) calculates the pseudo-propagation path characteristics of the channel model based on the transmitting antenna correlation and the receiving antenna correlation; a pseudo-channel capacity calculation step (S3, S6, S13) calculates the pseudo-channel capacity of the channel model from the pseudo-propagation path characteristics; and the difference between the actual propagation path channel capacity and the pseudo-channel capacity. Based on, The transmitting antenna correlation coefficient estimation step (S27) estimates the transmitting antenna correlation coefficient, The pseudo-channel capacity calculation step includes a transmitting antenna correlation calculation step (S13, S28) which calculates 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, and first calculates the pseudo-channel capacity based on the initial value of the transmitting antenna correlation coefficient, and repeats the processing of the transmitting antenna correlation coefficient estimation step, the transmitting antenna correlation calculation step, the pseudo-propagation path characteristic calculation step, and the pseudo-channel capacity calculation step until the difference between the actual propagation path channel capacity and the pseudo-channel capacity becomes smaller than a specified value, and the transmitting antenna correlation calculation step calculates the final transmitting antenna correlation using the transmitting antenna correlation coefficient when the difference between the actual propagation path channel capacity and the pseudo-channel capacity becomes smaller than the specified value. It is structured.

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

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

[0033] This invention provides a test system and a method for estimating transmitting antenna correlation that can accurately calculate transmitting antenna correlation by analyzing a precoded reference signal such as a DMRS. [Brief explanation of the drawing]

[0034] [Figure 1] This diagram schematically illustrates the environment of the actual propagation path between a base station and an antenna device. [Figure 2] This is a block diagram showing the configuration of a test system according to an embodiment of the present invention. [Figure 3] This is a diagram illustrating the definition of the receiving antenna correlation matrix. [Figure 4] This graph illustrates the processing performed by the transmitting antenna correlation coefficient estimation unit. [Figure 5] (a) is a graph illustrating the processing of the transmitting antenna correlation coefficient estimation unit when the pseudo-channel capacity is greater than the actual propagation path channel capacity, and (b) is a graph illustrating 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]This flowchart illustrates an example of the specific processing performed by the transmitting antenna correlation coefficient estimation unit, the pseudo-channel capacity calculation unit, and the pseudo-propagation path characteristic calculation unit. [Figure 7] This is a flowchart illustrating the process of a transmitting antenna correlation estimation method using a test system according to an embodiment of the present invention. [Figure 8] This is a diagram illustrating the precoding applied to the base station's transmitter. [Figure 9] This is a diagram illustrating the definition of the transmitting antenna correlation matrix. [Modes for carrying out the invention]

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

[0036] Figure 1 schematically shows the environment of the actual propagation path 110, which is a MIMO propagation path between a base station 100 and an antenna device 10, which are examples of network-side transceivers. In Figure 1, data communication between the base station 100 and the antenna device 10 is performed using multiple subcarriers with OFDM modulation.

[0037] The antenna device 10, in an environment of a real propagation path 110 consisting of multiple channels, provides N of the base station 100 TxAnt Transmitting antennas Tx#1~Tx#N TxAnt It receives downlink signals transmitted from the base station 100. For example, antenna device 10 is an air monitor or UE. Antenna device 10 is the transmitting antenna Tx#1~Tx#N of base station 100. TxAnt N receives the downlink signal transmitted from as the received signal. RxAnt Individual receiving antennas Rx#1~Rx#N RxAnt It also includes an IQ data output unit 11.

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

[0039] The IQ data output unit 11 is connected to the receiving antennas Rx#1 to Rx#N. RxAnt N received by RxAnt The system is configured to perform reception processing on each received signal, such as amplification, frequency conversion, and analog-to-digital conversion. Furthermore, the IQ data output unit 11 processes the received N RxAnt The individual received signals are demodulated, N RxAnt The system generates a pair of mutually orthogonal I-component baseband signals and Q-component baseband signals. In this specification, the I-component baseband signal and Q-component baseband signal 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) This is N, as shown in equation (4) below. TxAnt ×N RxAnt These are the elements of the actual propagation path matrix H(k,n) in the frequency domain of MIMO.

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

[0042] The test device 15 is equipped with the functions of a pseudo-base station device that generates the downlink signal necessary to test the device under test (DUT) 120 and transmits it to the DUT 120 via the pseudo-propagation path 40, and receives the uplink signal transmitted from the DUT 120 and performs the processing necessary for the test. The test device 15 is configured, for example, to test the demodulation performance of the DUT 120. The pseudo-propagation path 40 between the test device 15 and the DUT 120 is formed by parameters calculated by the parameter calculation unit 22, which will be described later. The DUT 120 is an UE capable of communication using at least the MIMO or MISO (Multiple Input Single Output) method.

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

[0044] The signal processing unit 20 is composed of a control device such as a computer, which includes, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an FPGA (Field Programmable Gate Array), a ROM (Read Only Memory), a RAM (Random Access Memory), and an HDD (Hard Disk Drive). Furthermore, the signal processing unit 20 can configure at least a portion of the actual propagation path estimation characteristic calculation unit 21, the parameter calculation unit 22, the actual propagation path channel capacity calculation unit 29, and the pseudo-channel capacity calculation unit 30 through software by executing a predetermined program by the CPU or GPU.

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

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

[0047] The actual propagation path estimation characteristic calculation unit 21 uses RS included in the IQ data output from the IQ data output unit 11 of the antenna device 10 to calculate the propagation path characteristics h in the frequency domain of the multiple channels constituting the actual propagation path 110. yx (k,n) Estimated characteristic h^ yx (k,n) It is designed to calculate [something].

[0048] Here, h yx (k,n) The following equation (4) represents the elements of the actual propagation path matrix H(k,n) of the actual propagation path 110. y is the N of the antenna device 10. RxAnt Individual receiving antennas Rx#1~Rx#N RxAnt This is the index, from 1 to R RxAnt It is an integer up to 100. x is the N of base stations 100. TxAnt Transmitting antennas Tx#1~Tx#N TxAnt This is an index, ranging from 1 to N. TxAnt It is an integer up to 1.

[0049] That is, N RxAnt= 1 and N TxAnt ≥2 is MISO format, N RxAnt ≥2 and N TxAnt ≥2 indicates the MIMO scheme.

[0050]

number

[0051] In equation (4), k is an index in the frequency axis direction, for example, the subcarrier number index. Here, if Δf is the frequency interval of the subcarriers, then the frequency f of each subcarrier k k × Δf. n is the index in the time axis direction, for example, the index of the 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 characteristics h yx (k,n) Assume that the average power is normalized to 1.

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

[0053] The actual propagation path estimation characteristic calculation unit 21 calculates the N of the base station 100. TxAnt Transmitting antennas Tx#1~Tx#N TxAnt The known RS included in the downlink signal transmitted from and the N output from the IQ data output unit 11 RxAnt From the RS of each channel included in the set of IQ data, the propagation path characteristics h yx (k,n) Estimated characteristic h^ yx (k,n) It is designed to calculate the estimated characteristic h^ yx(k,n) It includes information on the amplitude variation amount and phase variation amount of the RS of the IQ data obtained from the received signal received by the y-th receiving antenna Rx#y for the known RS transmitted by the x-th transmitting antenna Tx#x.

[0054] For example, in the case of the 5G NR standard, the actual propagation path estimation characteristic calculation unit 21 uses RS such as CSI-RS, DMRS, TRS, and PTRS included in the IQ data and the corresponding known RS for calculating the estimation characteristic h^ yx (k,n) Here, h^ yx (k,n) represents each element of the matrix H^(k,n) which is the estimated value of the actual propagation path matrix H(k,n) of the actual propagation path 110 in Equation (4), and is expressed as the following Equation (5).

[0055]

Equation

[0056] The parameter calculation unit 22 is configured to calculate parameters characterizing the statistical properties of the estimation characteristic h^ calculated by the actual propagation path estimation characteristic calculation unit 21. That is, the parameter calculation unit 22 uses the estimation characteristic h^ within a period during which the statistical properties can be considered not to have changed among the estimation characteristics h^ calculated by the actual propagation path estimation characteristic calculation unit 21 to calculate the parameters. The parameters calculated by the parameter calculation unit 22 are input to the virtual propagation path characteristic calculation unit 32 and the virtual propagation path 40.

[0057] ​​​​​​​​The pseudo-propagation path characteristic calculation unit 32 and the pseudo-propagation path 40 include known channel models such as the TDL model (Tapped Delay Line model) and the CDL model (Clustered Delay Line model). The pseudo-propagation path characteristic calculation unit 32 calculates the frequency characteristics of the pseudo-propagation path 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 device 15 and the DUT 120 based on the parameters of the channel model calculated by the parameter calculation unit 22.

[0060] The following example shows how the parameter calculation unit 22 calculates the "PDP," "K factor," "transmitting antenna correlation matrix," and "receiving antenna correlation matrix," using the TDL model as an example.

[0061] Estimated characteristic h^ yx (k,n) This is a frequency characteristic where k is the index in the frequency axis direction, but it has multiple delay taps τ corresponding to multiple paths. mt It can be represented by an impulse response consisting of [the specified components].

[0062] The impulse response calculation unit 23a calculates the estimated characteristic h^ in equation (5). yx (k,n) Therefore, the impulse response g in equation (6) below yx (mt,n)The following is calculated. Here, the generalized inverse of matrix A is represented as A+. Mt represents the number of delay taps, and mt is an integer from 1 to Mt. Matrix A is a type of Fourier transform matrix from which a column vector with the time-domain impulse response as an element can be calculated by multiplying it by a column vector with the time-domain impulse response as an element.

[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 system uses this to calculate the PDP, a parameter that represents the power-to-delay characteristics of an averaged delay tap. The PDP, normalized by the total power and expressed in dB, is calculated as shown in equation (7) below.

[0065]

number

[0066] In equation (7), P tap (mt) is expressed as shown in equation (8) below.

[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 used as the PDP, then the first delay tap P tap (1) The K factor K calculated by the K factor calculation unit 24 described later. allNLOS Using this, the calculation is performed as shown in equation (9) below.

[0069]

number

[0070] The K factor K shown in this embodiment allNLOS This parameter represents the ratio of the power of the line-of-situation (LOS) to the total power of the nonlinear line-of-situation (NLOS). The K-factor can be calculated without the influence of precoding, for example, by the method described in the references below.

[0071] Specifically, 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) By relating this to "V+v(t)" in equation (1) of the reference below, we can obtain the K factor K from equation (9) of the reference below. allNLOS It is designed to calculate [something].

[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 the TDL model, and the actual propagation path channel capacity C calculated by the actual propagation path channel capacity calculation unit 29, which will be described later. 1Hz The system is designed to calculate a transmitting antenna correlation that is equivalent to (ξ).

[0074] Transmitting antenna correlation is determined by multiple transmitting antennas Tx#1 to Tx#N TxAnt Transmitting antenna correlation matrix R shows the correlation between the propagation path characteristics from the receiving antenna Rx#y to each receiving antenna Rx#y. txcorr It is defined as an element of (α).

[0075] For example, the transmitting antenna correlation matrix R txcorr(α) can be modeled as a matrix that changes according to the transmitting antenna correlation coefficient α, as defined in Appendix B of 3GPP(registered trademark) TS38.101-4. Here, α is assumed to be a real number between 0 and 1. Equations (10a) to (10d) below are given by the number of transmitting antennas N TxAnt Transmitting antenna correlation matrix R for each of the following cases: txcorr (α) represents this.

[0076]

number

[0077] The pseudo-propagation path 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-propagation matrix H shows the pseudo-propagation characteristics of the channel model. sim The system calculates (α,n). This is the pseudo-propagation path matrix H in the frequency domain when using the TDL model as the channel model. sim (α,n) can be expressed as shown in equation (11) below.

[0078]

number

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

[0080]

number

[0081] L in equation (12a) rx The receiving antenna correlation matrix R is included in the rxcorr This involves multiple transmitting antennas Tx#1 to Tx#N TxAnt This is the receiving antenna correlation matrix that does not include the direct wave effect of the downlink signal. Receiving antenna correlation matrix R excluding the direct wave effect rxcorr The method for calculating this will be explained later.

[0082] In equation (12b), when α is 1, L tx (1) is R txcorr Let's consider a matrix of size (α) such that the leftmost column contains only 1s and the remaining columns contain only 0s. This is a matrix that can be expressed in R txcorr This is because (1) is not a positive definite matrix and therefore cannot be decomposed into a Cholesky matrix.

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

[0084] OnesRot in equation (11) NRxAnt×NTxAnt As shown in equation (13) below, the size is N RxAnt ×N TxAnt The magnitude of all elements is 1, and the relative phase θ of the direct wave is 1. R21 (x), θ R31 (x),···,θ RNRxAnt1 Estimated value of (x) θ^ R21 (x), θ^ R31 (x),···,θ^ RNRxAnt1 This is a matrix that contains (x). Here, θ Rab (x) or θ^ Rab (x) is the relative phase or estimated relative phase of the phase of the receiving antenna Rx#a with respect to the phase of the direct wave from a single transmitting antenna Tx#x at the receiving antenna Rx#b.

[0085]

number

[0086] Note that analysis in an environment where the LOS component does not exist (K factor K allNLOS For the case where (11) OnesRot NRxAnt×NTxAnt It is not necessary to calculate the first term which includes [the specified value].

[0087] Multiple transmitting antennas Tx#1~Tx#N TxAnt Estimated relative phase θ^ of the direct wave of the downlink signal between each receiving antenna Rx#y 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 pseudopropagation path matrix H of equation (11) sim The first term of (α,n) is the estimated relative phase θ^ of the direct wave. R21 (x), θ^ R31 (x),···,θ^ RNRxAnt1 This is the LOS component that includes (x). Also, the pseudo-propagation path matrix H in equation (11). sim The second term of (α,n) is the estimated relative phase θ^ of the direct wave. R21 (x), θ^ R31 (x),···,θ^ RNRxAnt1 This is an NLOS component that does not contain (x).

[0089] As can be seen from equations (12a) and (12b), the pseudopropagation path matrix H in equation (11) sim At (α,n), the receiving antenna correlation matrix R rxcorr and the transmitting antenna correlation matrix R txcorr (α) is included in the NLOS component.

[0090] As shown in Figure 3, the receiving antenna correlation calculation unit 26 calculates N from each transmitting antenna Tx#x. RxAnt Individual receiving antennas Rx#1~Rx#N RxAnt Estimated characteristics up to h^ yx (k,n) The receiving antenna correlation matrix R is a matrix whose elements are the receiving antenna correlations, which are the correlations between the receiving antennas. rxcorr It is designed to calculate [something].

[0091] The effect of precoding on the receiving antenna correlation can be explained as follows: Unlike the transmitting antenna correlation, the receiving antenna correlation can be calculated according to its definition without being affected by precoding.

[0092] For example, the correlation matrix R that includes 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 values ​​for k and n for the y1 row and y2 column components in (x) are h^ y1x (k,n) and h^ y2x (k,n) It is calculated as the correlation coefficient between h^. The correlation coefficient is as shown in equation (15) below. y1x (k,n) and h^ y2x (k,n) It depends on the relative phase between them.

[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) This includes one or more receiving antennas Rx#1 to Rx#N. RxAnt Since the transmitting antenna Tx#x is common to both, the phase due to precoding in equation (15) is ∠h^ y1x(prc) (k,n) and ∠h^y2x(prc) (k,n) is canceled out.

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

[0098]

Equation

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

[0100] The relative phase estimation unit 28 estimates the relative phases θ rxcorr_LOS (x) of the direct waves included in the correlation matrix R sim (x) and the pseudo propagation path matrix H R21 (α, n), θ R31 (x), θ RNRxAnt1 (x), ···, θ^{ R21 (x), θ^ R31 (x), ···, θ^ RNRxAnt1 (x).

[0101] Hereinafter, the procedure for the relative phase estimation unit 28 to calculate the estimated values θ^ R21 (x), θ^ R31 (x), ···, θ^ RNRxAnt1 (x) of the relative phases of the direct waves will be described. <�

[0102] For each transmission antenna Tx#x, a function f RLosPh (x) shown in the following formula (17) is defined. Here, |z| represents the magnitude of the complex number z, and f RLosPh (x) is a positive real number.

[0103]

Equation

[0104] The relative phase estimation unit 28 estimates the relative phase θ^ R21 (x), θ^ R31 (x),···,θ^ RNRxAnt1 For example, one of the following two methods can be used to calculate (x):

[0105] [Method 1 for estimating relative phase] 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).

[0106]

number

[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 by considering the speed of convergence and stability 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 the total relative phase may be zero.

[0109] Next, the relative phase estimation unit 28 calculates the relative phase θ. R21 (x), θ R31 (x),···,θ RNRxAnt1 Update (x) using equations (18a), (18b), and (18c), respectively. Numerical differentiation is used for partial derivatives.

[0110] Next, the relative phase estimation unit 28 performs calculations using equations (18a), (18b), and (18c) for each relative phase θ R21 (x), θ R31 (x),···,θ RNRxAnt1 The process is repeated until the update of (x) becomes sufficiently small, and the converged relative phase is used as the estimated relative phase θ^ R21 (x), θ^ R31 (x),···,θ^ RNRxAnt1 Let (x) be the case.

[0111] [Method 2 for estimating relative phase] The relative phase estimation unit 28 estimates the relative phase θ^ 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 which includes the effect of the direct wave. rxcorr_LOS Using the eigenvector u (in bold) corresponding to the largest eigenvalue obtained by eigenvalue decomposition of (x), we estimate the relative phase θ^ R21 (x), θ^ R31 (x),···,θ^ RNRxAnt1 (x) is calculated as shown in the following equations (19a), (19b), (19c), and (19d).

[0113]

number

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

[0115] By using Method 2, it is possible to calculate a reasonably approximate value while reducing the computational 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 value θ^ of the relative phase of the direct wave R21 (x), θ^ R31 (x), ···, θ^ RNRxAnt1 A supplementary explanation will be given as to why (x) is appropriate

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

[0118]

Number

[0119] The correlation matrix R including the influence of the direct wave rxcorr_LOS (x) is the column vector v (bold) consisting of the elements of the x-th column of H(n) in equation (20) RLosPh0 (x) is calculated as in the following equation (21) using (x).

[0120]

Number

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

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

[0123]

Number

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

[0125]

Number

[0126] The relative phase for which the first term in the absolute value of equation (23) is maximized is the relative phase θ of the direct wave. R21 (x), θ R31 (x),···,θ RNRxAnt1 It can be seen that it is (x) itself. In other words, considering that the statistical mean 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 can be seen that (x) is an appropriate approximation.

[0127] The following calculation is performed by the receiving antenna correlation calculation unit 26 using the K-factor calculated by the K-factor calculation unit 24 and the estimated relative phase θ^ calculated by the relative phase estimation unit 28. R21 (x), θ^ R31 (x),···,θ^ RNRxAnt1 Using (x), we create a correlation matrix R for each transmitting antenna Tx#x. rxcorr_LOS Correlation matrix R obtained by removing the direct wave effect from (x) rxcorr_NLOS The procedure for calculating (x) is explained below.

[0128] First, the receiving antenna correlation calculation unit 26 adjusts the phase of the correlation matrix R so that the phase of all direct waves is zero (in the real axis direction on the complex plane), as shown in equation (24) below. rxcorr_LOSadj Calculate (x). However, in equation (24), diag(v(bold)^ RLosPh (x) is a column vector v (bold)^ RLosPh This operator represents a diagonal matrix whose elements are the diagonal elements of (x). Also, v(bold)^ RLosPh (x) * is a column vector v (bold)^ RLosPh This is a column vector obtained by taking the conjugate of each element of (x).

[0129]

number

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

[0131]

number

[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 If so, the propagation path characteristics of those two channels are K factor K allNLOS Using this, they can be written as follows: equations (26a) and (26b).

[0134]

number

[0135] In equations (26a) and (26b), f SCS τ is the sample interval in the frequency axis direction. LOS is the propagation delay time of the LOS component. n is a complex random variable. i (k,n) and n j (k,n) These are random variables following a complex Gaussian distribution that are uncorrelated with each other and have a standard deviation of 1.

[0136] At this time, the correlation matrix R for each transmitting antenna Tx#x rxcorr_LOSThe i-th row and j-th column component of (x) is given by equation (27) below. However, in equation (27), statistical error is excluded by assuming that the sample size used for the mean is sufficiently large.

[0137]

number

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

[0139] One or more receiving antennas Rx#1~Rx#N RxAnt Assuming that we can accurately estimate the relative phase of the direct waves at , we obtain a correlation matrix R whose phase is adjusted so that the phase of all direct waves becomes zero. rxcorr_LOSadj The i-th row and j-th column component of (x) r^ Rij This is expressed as shown in equation (28) below.

[0140]

number

[0141] However, in equation (28), the correlation matrix R is obtained by eliminating the effect of the direct wave. 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 equation (29) below.

[0143]

number

[0144] When the i-th row and j-th column component of equation (29) is combined for all elements, we get R in equation (25). rxcorr_NLOS (x) is obtained.

[0145] The receiving antenna correlation calculation unit 26 calculates the correlation matrix R in equation (25). rxcorr_NLOS By averaging (x) over all transmitting antennas Tx#x, we obtain the receiving antenna correlation matrix R shown in equation (30) below. rxcorr Calculate.

[0146]

number

[0147] The receiving antenna correlation matrix R obtained by equation (30) rxcorr This is a correlation matrix that does not include the direct wave effect, and L in equation (11) rx This is input to the following: Note that analysis in an environment where the LOS component does not exist (K factor K) allNLOS For cases where (the value is 0), the correlation matrix R is obtained by eliminating the influence of the direct wave. rxcorr_NLOS (x) is the correlation matrix R before the direct wave effect is removed. 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) From this, the channel capacity C0 [bit / sec / Hz] of the actual propagation path 110 is calculated. Here, the channel capacity C0 is the channel capacity at each (k,n) to which RS is allocated. The channel capacity can be said to be the upper limit of theoretical throughput and an indicator of how easily throughput can be achieved. Throughput is determined by the modulation scheme, error correction method, amount of wireless resource allocation, etc.

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

[0150]

number

[0151] Here, ξ is the SNR (Signal-to-Noise Ratio) (linear value) per receiving antenna Rx#y. λ i (k,n) is H^(k,n)H^(k,n) H This is the i-th eigenvalue. The index i ranges from 1 to N. TxAnt and N RxAnt This is the smallest value of H^(k,n). H This is the conjugate transpose of the matrix H^(k,n) representing the estimation characteristics of the actual propagation path matrix.

[0152] Furthermore, the actual propagation path channel capacity calculation unit 29 calculates the actual propagation path channel capacity C, which is the average of the channel capacity C0 of the actual propagation path 110 in a bandwidth with K subcarriers and N OFDM symbols. 1Hz (ξ)[bit / sec / Hz] is calculated according to the following formula (32).

[0153]

number

[0154] The pseudo-channel capacity calculation unit 30 calculates the pseudo-propagation path matrix H calculated by the pseudo-propagation path characteristics calculation unit 32, as shown below. sim From (α,n), the pseudo-channel capacitance C of the channel model. Sim1Hz The system is designed to calculate (ξ,α).

[0155] Here, the pseudo-propagation path matrix H obtained by equation (11) sim For (α,n), H sim (α,n)H sim (α,n) H The eigenvalues ​​obtained when decomposing the eigenvalues ​​of λ are λ p sim(α,n) Assume that the index p ranges from 1 to N. TxAnt and N RxAnt This is the smallest possible value.

[0156] At this time, the pseudo-channel capacity calculation unit 30 calculates N=N sym Pseudopropagation path matrix H for each number simUsing (α,n), the pseudo-propagation path matrix H sim The pseudo-channel capacity C is the average value of the channel capacity of (α,n). Sim1Hz (ξ,α) is calculated as shown in equation (33) below. sym The specific numerical value needs to be adjusted by considering the balance between processing time and result variability, but for example, N sym It can be set to a value of approximately 1000.

[0157]

number

[0158] The transmitting antenna correlation coefficient estimation unit 27 calculates the actual propagation path channel capacity C calculated by the actual propagation path channel capacity calculation unit 29. 1Hz (ξ) and the pseudo-channel capacity C calculated by the pseudo-channel capacity calculation unit 30 Sim1Hz The system is designed to estimate the transmitting antenna correlation coefficient α such that the difference between (ξ,α) is smaller than a specified value.

[0159] For example, the transmitting antenna correlation coefficient estimation unit 27 calculates the pseudo-channel capacitance C when ξ = 1000 (i.e., SNR is 30 dB). Sim1Hz (ξ,α) is the actual propagation channel capacity C 1Hz We find α such that it is approximately equal to (ξ). In other words, the actual propagation channel capacitance C 1Hz (ξ) is the pseudo-channel capacitance 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 the transmitting antenna correlation matrix R txcorr By substituting (α), multiple transmitting antennas Tx#1~Tx#N TxAnt Estimated characteristics h^ from each receiving antenna Rx#y yx (k,n) The transmitting antenna correlation matrix R shows the correlation between the transmitting antennas. txcorr It is calculated using (α).

[0161] The following describes a specific example of the processing performed by the transmitting antenna correlation coefficient estimation unit 27, the pseudo-channel capacity calculation unit 30, and the pseudo-propagation path characteristic calculation unit 32, referring to the graphs in Figures 4, 5(a) and (b), and the flowchart in Figure 6. Explanations that overlap with the above-described explanation of the test system 1 configuration will be omitted as appropriate.

[0162] As shown in Figure 4, the pseudo-channel capacitance C of equation (33) Sim1Hz Of the values ​​of α in (ξ,α), the value used for the following process is α m , α m―1(max) , and α m―1(min) (m is an integer greater than or equal to 1, which is used as an index to count the number of repetitions) and so on. Also, when narrowing down the range of α and the corresponding range of channel capacity through iterative processing, α = α m―1(max) C at that time Sim1Hz (ξ,α m―1(max) The value of ) is the upper limit of channel capacity C max Corresponding to α=α m―1(min) C at that time Sim1Hz (ξ,α m―1(min) The value of ) is the lower limit of channel capacity C min This shall correspond to C. Sim1Hz (ξ,α) is considered to be a monotonically decreasing function of α, therefore α m―1(max) ≤α m―1(min) That is the case.

[0163] As shown in Figure 6, first, the transmitting antenna correlation coefficient estimation unit 27 sets the initial value of 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) Set the value to 0 (step S2).

[0165] Next, the pseudo propagation path characteristic calculation unit 32 calculates N sym Pseudopropagation path matrix H for each number sim The pseudo-channel capacity calculation unit 30 calculates (0,n). symPseudopropagation path matrix H for each number sim Using (0,n), the pseudo-channel capacitance C Sim1Hz Calculate (ξ,0) (Step S3).

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

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

[0168] Next, the pseudo propagation path characteristic calculation unit 32 calculates N sym Pseudopropagation path matrix H for each number sim The pseudo-channel capacity calculation unit 30 calculates (1,n). sym Pseudopropagation path matrix H for each number sim Using (1,n), the pseudo-channel capacitance C Sim1Hz Calculate (ξ,1) (Step S6).

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

[0170] The target channel capacity is the actual propagation path channel capacity C. 1Hz (ξ) is C min The above and C max If the following is true (Step S8: YES), the process in Step S12 will be executed.

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

[0172] Meanwhile, target C 1Hz (ξ) is C min If it is smaller than (Step S9: NO), the transmitting antenna correlation coefficient estimation unit 27 sets the value of α1 to α 0(min) Set to =1 (step S11). Then, the process in step S19 is executed.

[0173] In step S12, the transmitting antenna correlation coefficient estimation unit 27 calculates the target C using the following equation (34). 1Hz α corresponding to (ξ) m We estimate (step S12). Equation (34) is given by C as shown in Figure 4. Sim1Hz (ξ,α) is α m―1(max) From α m―1(min) Considering α to be a linear function within the range α m This is an equation for estimating [the value].

[0174]

number

[0175] Next, the pseudo propagation path characteristic calculation unit 32 calculates α obtained by equation (34). m N corresponding to sym Pseudopropagation path matrix H for each number sim (α m The pseudo-channel capacity calculation unit 30 calculates N sym Pseudopropagation path matrix H for each number sim (α m Using n), the pseudo-channel capacitance C Sim1Hz (ξ,α m Calculate (Step S13).

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

[0177]

number

[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 determines, as shown in Figure 5(a), C max The value of C Sim1Hz (ξ,α m ) to α m(max) The value of α m , α m(min) The value of α m―1(min) Set to (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 determines C as shown in Figure 5(b). min The value of C Sim1Hz (ξ,α m ) to α m(min) The value of α m , α m(max) The value of α m―1(max) Set to (step S17).

[0180] Next, the transmitting antenna correlation coefficient estimation unit 27 increments the current index m value by 1 (step S18). Then, the processing from step S12 onward is executed again.

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

[0182] Thus, the transmitting antenna correlation coefficient estimation unit 27 determines α m―1(max) From α m―1(min) Gradually narrowing the range of α m The value of is calculated, and the actual propagation path channel capacity C 1Hz Pseudo-channel capacitance C close to (ξ) Sim1Hz Determine the α from which (ξ,α) is obtained.

[0183] Steps S3, S6, and S13 are performed using the K factor K. allNLOS And the transmitting antenna correlation matrix R txcorr (α) and the receiving antenna correlation matrix R rxcorr Based on this, the pseudo-propagation path matrix H of the channel model sim (α m A pseudo-propagation path characteristic calculation step that calculates n) and the pseudo-propagation path matrix H sim (α m From n) the pseudo-channel capacitance C of the channel model Sim1Hz This constitutes a pseudo-channel capacity calculation step that calculates (ξ,α).

[0184] The pseudo-propagation path characteristics calculation step involves estimating the relative phase of the direct wave θ^ R21 (x), θ^ R31 (x),···,θ^ RNRxAnt1 The LOS component including (x) and the estimated relative phase of the direct wave θ^ R21 (x), θ^ R31 (x),···,θ^ RNRxAnt1 The pseudo-propagation path matrix H is the sum of the NLOS component that does not include (x). sim Calculate (α,n).

[0185] Below, an example of the method for estimating the transmitting antenna correlation using the test system 1 of this embodiment will be described with reference to the flowchart in Figure 7. Note that explanations that overlap with the above-described explanation of the configuration of the test system 1 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 uses the RS included in the IQ data input in step S21 to calculate the propagation path characteristics h of the multiple channels constituting the actual propagation path 110. yx (k,n) Estimated characteristic h^ yx (k,n) This 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) Therefore, the actual propagation path channel capacity C of the actual propagation path 110. 1Hz (ξ) is calculated (actual propagation 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 The K factor is calculated (K factor calculation step S24).

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

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

[0192] Next, the transmitting antenna correlation coefficient estimation unit 27, the pseudo-channel capacity calculation unit 30, and the pseudo-propagation path characteristic calculation unit 32 calculate the actual propagation path channel capacity C through the processing in steps S1 to S19 described above. 1Hz (ξ) and pseudo-channel capacitance C Sim1Hz The transmitting antenna correlation coefficient α is estimated such that the difference with (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 Transmitting antenna correlation matrix R txcorr (α m Substitute this into the formula for multiple transmitting antennas Tx#1~Tx#N TxAnt Estimated characteristics h^ from each receiving antenna Rx#y yx (k,n) The transmit antenna correlation, which is the correlation between the two, is calculated (transmit antenna correlation calculation step S28).

[0194] Next, the signal processing unit 20 processes the transmit antenna correlation matrix R calculated by the transmit 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 propagation path channel capacity 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 based on the channel model. Sim1Hz The system is designed to calculate the transmitting antenna correlation such that (ξ,α) are equivalent.

[0196] As a result, the test system 1 according to this embodiment can analyze precoded RS signals such as DMRS and accurately estimate the transmitting antenna correlation.

[0197] When performing throughput testing using a channel model, it is sometimes necessary to obtain a throughput value close to that achieved in an actual MIMO propagation environment. Since channel capacity represents theoretically achievable throughput, propagation paths with equivalent channel capacity can be said to be propagation paths that can obtain equivalent throughput. Therefore, by using the test system 1 according to this embodiment, it becomes possible to perform throughput testing of DUT120 with a channel model that can obtain throughput equivalent to that of an actual MIMO propagation path.

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

[0199] As a result, the test system 1 according to this embodiment has a pseudo-channel capacitance C that reflects the phase relationship of the LOS component, similar to 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 perform tests on the DUT 120 by reproducing the statistical propagation characteristics of the actual propagation path 110 using pseudo propagation path characteristics.

[0201] In the embodiment described above, the network-side transceiver that transmits downlink signals toward the actual propagation path 110 is assumed to be a base station 100. However, instead of a base station, a Wi-Fi® access point or the like may be used as the network-side transceiver. [Explanation of Symbols]

[0202] 1. Test System 10 Antenna equipment 11. IQ Data Output Unit 15 Test equipment 20 Signal Processing Unit 21 Actual propagation path estimation characteristic calculation unit 22 Parameter Calculation Unit 24K Factor Calculation Unit 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 paths 41 Display section 100 Base stations (network-side transceivers) 110 Actual propagation paths 120 DUT Rx#1~Rx#N RxAnt Receiving antenna Tx#1~Tx#N TxAnt Transmitting antenna

Claims

1. Multiple transmitting antennas (Tx#1 to Tx#N) of the network-side transceiver (100) ＴｘＡｎｔ The downlink signal transmitted from ) is received in the environment of the actual propagation path (110) by one or more receiving antennas (Rx#1 to Rx#N ＲｘＡｎｔ A real propagation path estimation characteristic calculation unit (21) calculates the estimation characteristics of the propagation path characteristics of the actual propagation path using a reference signal included in the IQ data of the downlink signal output from the antenna device (10) that receives the signal, A real propagation path channel capacity calculation unit (29) calculates the real propagation path channel capacity of the real propagation path from the estimated characteristics, A K-factor calculation unit (24) calculates the K-factor from the estimated characteristics, A receiving antenna correlation calculation unit (26) calculates the receiving antenna correlation, which is the correlation between the estimated characteristics from each of the transmitting antennas to the one or more receiving antennas, A pseudo-propagation path characteristic calculation unit (32) calculates the pseudo-propagation path characteristics of the channel model based on the K-factor, the transmitting antenna correlation which is the correlation between the estimated characteristics from the plurality of transmitting antennas to each of the receiving antennas, and the receiving antenna correlation. A pseudo-channel capacity calculation unit (30) calculates the pseudo-channel capacity of the channel model from the pseudo-propagation path characteristics, A transmitting antenna correlation coefficient estimation unit (27) estimates the transmitting antenna correlation coefficient based on the difference between the actual propagation path channel capacity and the pseudo-channel capacity, The system includes a transmitting antenna correlation calculation unit (25) which 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, The pseudo-channel capacity calculation unit first calculates the pseudo-channel capacity based on the initial value of the transmitting antenna correlation coefficient, The processing of the transmitting antenna correlation coefficient estimation unit, the transmitting antenna correlation calculation unit, the pseudo-propagation path characteristic calculation unit, and the pseudo-channel capacity calculation unit is repeated until the difference between the actual propagation path channel capacity and the pseudo-channel capacity becomes smaller than a specified value. The test system is characterized in that the transmitting antenna correlation calculation unit calculates the final transmitting antenna correlation using the transmitting antenna correlation coefficient when the difference between the actual propagation path channel capacity and the pseudo-channel capacity becomes smaller than the specified value.

2. The system further includes a relative phase estimation unit (28) that calculates an estimated value of the relative phase between each of the receiving antennas of the direct waves of the downlink signals from the plurality of transmitting antennas, The test system according to claim 1, characterized in that the pseudo-propagation path characteristic calculation unit calculates the pseudo-propagation path characteristic which is the 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. The test system according to claim 2, characterized in that the receiving antenna correlation calculation unit calculates the receiving antenna correlation in such a way as to eliminate the influence of the direct wave component, which includes the estimated value of the relative phase of the direct wave.

4. The test system according to claim 3, characterized in that the receiving antenna correlation and the transmitting antenna correlation are included in the scattered wave component in the pseudo propagation path characteristics.

5. Multiple transmitting antennas (Tx#1 to Tx#N) of the network-side transceiver (100) ＴｘＡｎｔ The downlink signal transmitted from ) is received in the environment of the actual propagation path (110) by one or more receiving antennas (Rx#1 to Rx#N ＲｘＡｎｔ The actual propagation path estimation characteristic calculation step (S22) calculates the estimation characteristics of the propagation path characteristics of the actual propagation path using a reference signal included in the IQ data of the downlink signal output from the antenna device (10) that receives the signal, The actual propagation path channel capacity calculation step (S23) calculates the actual propagation path channel capacity of the actual propagation path from the estimated characteristics, A K-factor calculation step (S24) in which the K-factor is calculated from the estimated characteristics, A receiving antenna correlation calculation step (S26) is performed to calculate the receiving antenna correlation, which is the correlation between the estimated characteristics from each of the transmitting antennas to the one or more receiving antennas. A pseudo-propagation path characteristic calculation step (S3, S6, S13) calculates the pseudo-propagation path characteristics of the channel model based on the K-factor, the transmit antenna correlation which is the correlation between the estimated characteristics from the plurality of transmit antennas to each of the receive antennas, and the receive antenna correlation. A pseudo-channel capacity calculation step (S3, S6, S13) is performed to calculate the pseudo-channel capacity of the channel model from the pseudo-propagation path characteristics, A transmitting antenna correlation coefficient estimation step (S27) is performed to estimate the transmitting antenna correlation coefficient based on the difference between the actual propagation path channel capacity and the pseudo-channel capacity, The process includes a transmitting antenna correlation calculation step (S13, S28) which calculates 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, The pseudo-channel capacity calculation step first calculates the pseudo-channel capacity based on the initial value of the transmitting antenna correlation coefficient, The steps of estimating the transmitting antenna correlation coefficient, calculating the transmitting antenna correlation, calculating the pseudo-propagation path characteristics, and calculating the pseudo-channel capacity are repeated until the difference between the actual propagation path channel capacity and the pseudo-channel capacity becomes smaller than a specified value. The transmitting antenna correlation estimation method is characterized in that the transmitting antenna correlation calculation step calculates the final transmitting antenna correlation using the transmitting antenna correlation coefficient when the difference between the actual propagation path channel capacity and the pseudo channel capacity becomes smaller than the specified value.

6. The process further includes a relative phase estimation step (S25) for calculating an estimated relative phase of the direct waves of the downlink signals from the plurality of transmitting antennas between each of the receiving antennas, The transmitting antenna correlation estimation method according to claim 5, characterized in that the pseudo-propagation path characteristic calculation step calculates the pseudo-propagation path characteristic which is the 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.

7. The method for estimating a transmitting antenna correlation according to claim 6, characterized in that the receiving antenna correlation calculation step calculates the receiving antenna correlation in such a way as to eliminate the influence of the direct wave component, which includes an estimated value of the relative phase of the direct wave.

Images