CN112583459B - Method and system for sequencing streams of MIMO (multiple input multiple output) signals - Google Patents

Method and system for sequencing streams of MIMO (multiple input multiple output) signals Download PDF

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CN112583459B
CN112583459B CN202011626172.1A CN202011626172A CN112583459B CN 112583459 B CN112583459 B CN 112583459B CN 202011626172 A CN202011626172 A CN 202011626172A CN 112583459 B CN112583459 B CN 112583459B
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CN112583459A (en
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蒋芜
吴建兵
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Shenzhen Itest Technology Co ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0602—Systems characterised by the synchronising information used
    • H04J3/0605—Special codes used as synchronising signal
    • H04J3/0608—Detectors therefor, e.g. correlators, state machines
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0224—Channel estimation using sounding signals
    • H04L25/0228—Channel estimation using sounding signals with direct estimation from sounding signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/024—Channel estimation channel estimation algorithms
    • H04L25/0242—Channel estimation channel estimation algorithms using matrix methods
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L7/00—Arrangements for synchronising receiver with transmitter
    • H04L7/04—Speed or phase control by synchronisation signals
    • H04L7/041—Speed or phase control by synchronisation signals using special codes as synchronising signal
    • H04L7/042—Detectors therefor, e.g. correlators, state machines

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Abstract

The invention provides a stream ordering method and a system of MIMO signals, wherein the stream ordering method comprises the following steps: step S1, based on the long training sequence LTF, realizing frame synchronization to MIMO signal sliding correlation; step S2, performing stream sorting based on the frame synchronization result obtained in step S1; step S3, calculating the carrier frequency offset of each data stream, and carrying out carrier frequency offset compensation on the whole stream signal; step S4, realizing initial channel estimation based on long training sequence LTF; step S5, analyzing frame system information based on initial channel estimation; step S6, stream sorting is performed based on the data training sequence. The invention can effectively solve the problem of analysis failure of the tester caused by wrong connection between the DUT and the tester and disordered space-time flow of signals when the DUT sends wave beam forming signals, reduces the MIMO test complexity of the DUT and improves the test flexibility of the tester.

Description

Method and system for sequencing streams of MIMO (multiple input multiple output) signals
Technical Field
The invention relates to a stream ordering method, in particular to a stream ordering method for analyzing MIMO signals under 802.11n/ac/ax standard by using a tester, and a stream ordering system adopting the stream ordering method.
Background
In a modern wireless communication system, the capacity of the system is greatly improved by combining the OFDM technology and the MIMO technology. The 802.11n, 802.11ac, and 802.11ax standards promulgated by the Wi-Fi alliance all employ these two technologies.
For a DUT (device under test) supporting MIMO, each data stream carries different information, when a test is developed or a production test is performed, multiple data streams of the DUT are sent out using different radio frequency antenna ports, an RF (radio frequency) unit is required to be used by a tester to collect signals of the data streams, each antenna port needs to correspond to one set of RF unit of the tester, and the test method in which the DUT antenna ports and the tester RF units are in one-to-one correspondence is called True MIMO test. As shown in fig. 2, this is a 4 × 4 True MIMO test environment, and the DUTs are sequentially connected to the RF unit of the tester according to the antenna port, and the tester performs signal analysis and result output according to the signals collected by the RF unit.
The frame structure of 11n is shown in fig. 4, the frame structure of 11ac is shown in fig. 5, the frames of 11ax are divided into four kinds, as shown in fig. 6-9, where 11ax SU uses the whole bandwidth for MIMO transmission, 11ax ER, 11ax MU, and 11ax TB may use part of the bandwidth for data transmission, and the bandwidths occupied by different streams may be different.
When the DUT performs MIMO testing, the number of antennas increases, which may lead to complex connection and easily cause misconnection of antennas, as shown in fig. 3. In addition, the tester may be unaware of the DUT antenna port and experience wiring errors. When the tester analyzes, if the stream sequence is incorrect, the MIMO channel estimation will be wrong because of the mismatching of the training sequence characteristics, in addition, the mode of each stream in the de-interleaving process is different, and the error of the stream sequence number inevitably leads to the de-interleaving error, so the signal analysis fails. In addition, the bandwidth allocation on the 11ax mode different streams is flexible and if the stream sequence number is wrong, it may even happen that some users' data is lost. How to correctly identify the stream sequence of the MIMO signal by the tester is a technical problem that cannot be ignored.
Each of 11n, 11ac, and 11ax includes a short training sequence STF and a long training sequence LTF field, and each stream is cyclically shifted by a stream number in order to reduce inter-stream interference of the MIMO signal. The training sequence without cyclic shift is used to make sliding correlation with the received MIMO signal, because of the difference of cyclic shift, the frame head position obtained by each stream is also different, and the method can be used to sequence the MIMO signal.
However, the stream ordering method using the cyclic shift characteristic to obtain the frame header position difference characteristic is not necessarily applicable in the multipath channel environment. Also, when the DUT performs beamforming transmission, the same data stream may be transmitted over multiple antenna ports, and when the tester analyzes the data stream, the analysis may fail if the correct stream number is not identified.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a stream ordering method for MIMO signals, so that the stream sequence transmitted by the device to be tested to the tester is regular, and each index of the device to be tested signal can be successfully analyzed at the tester according to the normal stream ordering, thereby effectively reducing the complexity of the MIMO test of the device to be tested, and improving the test flexibility of the tester.
To this end, the present invention provides a method for sequencing streams of MIMO signals, comprising the steps of:
step S1, based on the long training sequence LTF, realizing frame synchronization to MIMO signal sliding correlation;
step S2, based on the frame synchronization result obtained in step S1, performing stream sequencing, wherein the stream sequencing is realized by performing header L of all streamsstart(i) According to the total number of received data streams NrAnd frame header L of each streamstart(i) Sorting the relationship of the sizes; i is a natural number and is used to represent a cyclic variable, such as a stream sequence number of a MIMO signal, where the ith MIMO signal is also referred to as MIMO signal stream i, MIMO signal space-time stream i, ith stream, or stream i;
step S3, calculating the carrier frequency offset of each data stream, and carrying out carrier frequency offset compensation on the whole stream signal;
step S4, realizing initial channel estimation based on long training sequence LTF;
step S5, analyzing frame system information based on initial channel estimation;
step S6, stream sorting is performed based on the data training sequence.
In a further improvement of the present invention, in the step S1, the formula L is usedstart＝LLTFFrame header L after frame synchronization is obtained by 9.6us FsstartWhere us is the unit of time in microseconds and Fs is the sampling rate.
The further improvement of the invention is that the process of carrying out coarse synchronization on the MIMO signal by the short training sequence S-LTF comprises the following steps: performing sliding correlation operation on an ideal time domain signal x (t) of a local known long training sequence LTF on a received time domain signal y (t), and searching two obvious Peak values Peak (C (t) in a correlation value C (t) of the sliding correlation operation1)),Peak(C(t2) And the time interval between two peaks, Δ τ ═ (t)2-t1) The interval period of Fs exactly corresponding to the long training sequence LTF is 3.2us (microseconds), then the position t where the first peak appears is taken1As long training sequence LTF start position LLTF，t2Is the second oneWhere the peak occurs.
In a further improvement of the present invention, in step S2, if the flow order is not correct, the flow order is determined according to the frame header Lstart(i) The streams are reordered according to a preset cyclic shift table, and after reordering, the frame headers L of the received streamsstart(i) Conforming to the cyclic shift characteristic, the frame header of the whole MIMO signal is re-sequenced with the frame header L after the re-sequencingstart(1) Is the new frame header position.
In a further improvement of the present invention, in the step S3, the formula is used
Figure BDA0002874901190000031
Calculating carrier frequency deviation type delta f of each data streamltf(i)Then taking the average of the frequency offsets of all streams as
Figure BDA0002874901190000032
And by the formula
Figure BDA0002874901190000033
Carrying out carrier frequency offset compensation on the whole flow signal; where Δ t is the repetition interval duration of the long training sequence LTF, Rltf(i)Calculating an intermediate index for the frequency offset of the MIMO signal stream i; y isi(t) is a complex signal representation of the MIMO signal stream i at time t; 1j is an imaginary unit; the compensation interval t belongs to [1N ]]And N is the total sampling point of the MIMO signal receiving.
In the step S5, the method further includes equalizing the received fields of HT-SIG, VHT-SIG, and HE-SIG based on the initial channel estimation, analyzing the fields of HT-SIG, VHT-SIG, and HE-SIG according to the protocol definition, and obtaining an analysis message of the signal, including the PHT matrix P used by the MIMO signal and the total number N of space-time streams of the signalstsThe total number of training sequences N of the signal dataLTFAnd MIMO signal stream i carrier bearing state Ai,i＝1,…,Nsts。
A further refinement of the invention is that said step S6 comprises the following sub-steps:
step S601, for the ith receiving antenna, i is 1, …, NrEach data stream having NLTFPositioning the data training sequence to the time domain position of the data training sequence, transforming the data training sequence to the frequency domain through Fourier transform, and recording the j-th data training sequence frequency domain of the i-th receiving antenna as Yi,j＝[yi,j,1,yi,j,2,…,yi,j,K]TWherein N isrRepresenting the total number of streams received, yi,j,kThe data of the subcarrier with the frequency domain serial number of k on the jth data training sequence of the ith receiving antenna is represented, and the superscript T is transposition; j is a natural number for representing a cyclic variable of the symbol; k is a natural number for representing a cyclic variable of the subcarrier;
step S602, calculating a data training sequence correlation value;
step S603, calculating flow information;
step S604, determining whether reordering and processing are needed, and when i ≠ p exists, reordering the received streams according to the analyzed size of p, and after reordering, changing p to 1 and p to NstsThe stream enters the subsequent analysis, i is the stream sequence number when receiving the MIMO signal, p is the stream sequence number of the stream at the transmitting end when receiving the MIMO signal, NstsIs the number of signal space-time streams.
The invention is further improved in that in the step S602, the formula is used
Figure BDA0002874901190000034
Calculating data training sequence correlation zi,jK is the total number of received data subcarriers, yi,j,kIndicating the subcarrier data with the frequency domain sequence number equal to k on the j data training sequence of the receiving antenna i, yi,1,kThe data indicates subcarrier data of which the frequency domain sequence number is equal to k of the ith receiving antenna on the 1 st data training sequence, that is, on the received MIMO signal stream i, the data obtained by dividing the jth data training sequence and the 1 st data training sequence point by point according to the subcarrier sequence number k.
The present invention is further improved in that in the step S603, the formula is used
Figure BDA0002874901190000035
Figure BDA0002874901190000041
Calculating flow information Ri,k,k∈[1Nsts]Wherein N isLTFFor the total number of training sequences, N, of the signal data parsed in step S5stsThe total number of space-time streams, P, of the signal analyzed in step S5i,jI row and j column of PHT matrix defined for protocol, Ai,kResolving the state of the carrying data of the ith sending flow on the subcarrier k for the step S5, and resolving the state A of the carrying data of the ith sending flow on the subcarrier ki,kData-carrying subcarrier a for shorti,kIf the signal exists, the signal is 1, and if the signal does not exist, the signal is 0; n is a radical ofi,AFor carrying data subcarrier Ai,kThe number of the carbon atoms is not 0. For a received MIMO signal stream i, R is comparedi,1To
Figure BDA0002874901190000042
Selecting the maximum value Ri,pP is the stream sequence number of the sending end, and p belongs to [1N ]sts]That is, the current received MIMO signal stream i, the stream sequence number corresponding to the transmitting end is p;
the present invention also provides a MIMO signal stream ordering system, which adopts the above MIMO signal stream ordering method, and includes:
the frame synchronization module is used for realizing frame synchronization on the MIMO signal sliding correlation based on the long training sequence LTF;
a stream sequencing module for performing stream sequencing based on the frame synchronization result obtained in the step S1, wherein the stream sequencing is realized by performing frame header L of all streamsstart(i) According to the total number of received data streams NrAnd frame header Lstart(i) Sorting the relationship of the sizes;
the frequency offset estimation and compensation module is used for calculating the carrier frequency offset of each data stream and carrying out carrier frequency offset compensation on the whole stream signal;
the initial channel estimation module is used for realizing initial channel estimation based on the long training sequence LTF;
the system message analysis module analyzes the frame system message based on the initial channel estimation;
and the flow ordering module is used for carrying out flow ordering based on the data training sequence.
Compared with the prior art, the invention has the beneficial effects that: the method and the system for sequencing the streams of the MIMO signals are suitable for analyzing a plurality of data streams by using a tester under the 802.11n/ac/ax standard MIMO scene, and can effectively solve the problem of analysis failure of the tester, such as the problem of failure caused by wrong connection between a device to be tested and the tester or the problem of failure caused by disordered space-time streams of signals when the device to be tested sends beamforming signals. According to the invention, the tester can reorder the data streams according to the input signal characteristics, so that the stream sequence transmitted to the tester by the equipment to be tested is regular, and after the stream ordering is completed at the tester end, each index of the transmitted signal is successfully analyzed, thereby effectively reducing the MIMO test complexity of the equipment to be tested and improving the test flexibility of the tester.
After the invention is used, the MIMO signal test does not need to consider the problem of matching of the DUT antenna serial number and the RF serial number of the tester, thereby reducing the complexity of the MIMO signal test and leading the test to be more flexible.
Drawings
FIG. 1 is a schematic workflow diagram of one embodiment of the present invention;
FIG. 2 is a schematic diagram of a True MIMO test networking mode;
FIG. 3 is a schematic diagram of a True MIMO test networking misalignment pattern;
FIG. 4 is a schematic diagram of the structure of an 11n frame;
FIG. 5 is a schematic of the structure of an ac frame structure;
fig. 6 is a schematic diagram of the structure of an 11ax SU frame structure;
FIG. 7 is a schematic diagram of the structure of an 11ax ER frame structure;
FIG. 8 is a schematic diagram of an 11ax MU frame structure;
FIG. 9 is a schematic diagram of the structure of an 11ax TB frame structure;
FIG. 10 is a schematic diagram of flow 1 and flow 2 chaotic analysis result anomaly simulation;
FIG. 11 is a simulation diagram of the analysis result of the flow 1 and the flow 2 after the flow sorting algorithm is adopted.
Detailed Description
Preferred embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.
When the DUT carries out MIMO test, the tester needs to collect each data stream of the DUT at the same time, because the MIMO connection line may be disordered, or the DUT can send two data streams which are the same as each other when the DUT carries out beam forming, or in order to test the performance of cross connection, the scene of disordered stream sequencing requires the tester to be capable of correctly distinguishing and analyzing. After the invention is applied, the problem of matching of the DUT antenna serial number and the RF serial number of the tester is not needed to be considered in the MIMO signal test, the complexity of the DUT MIMO test is reduced, and the test flexibility of the tester is improved.
This example is applicable to testing equipment for performance testing of DUTs, and after completion of the flow ordering of step S6, the remaining work is done in the conventional manner of signal processing and calculation of metrics.
For MIMO signal reception, each protocol defines a data training sequence of a plurality of symbols, the data training sequence of 802.11n is HT-LTF, the data training sequence of 802.11ac is VHT-LTF, and the data training sequence of 802.11ax is HE-LTF. When the transmitting end has NstsFor each space-time data stream to be transmitted, there are N for each space-time data streamLTFA training sequence of symbols, wherein the total number N of the space-time data streams to be transmittedstsAnd the total number of data training sequences NLTFThe relationship is
Figure BDA0002874901190000051
I.e. the total number of training sequences of data NLTFAlways an even number.
The MIMO signal data training sequence design rule is as follows, first defining a base sequence of data training sequence, whose frequency domain is represented by X ═ X1,x2,…,xM]TWhere M is the total number of subcarriers, Ai＝[a1,a2,…,aM]T,i＝1,…,NstsA value is assigned to a subcarrier of the MIMO signal stream i,
Figure BDA0002874901190000061
in 11n, 11ac and 11ax SU, Ai＝[a1,a2,…,aM]TIs the same, in 11ax ER, 11ax MU and 11ax TB, Ai＝[a1,a2,…,aM]TMay or may not be identical.
In addition, the MIMO designs an orthogonal PHT matrix for constructing an orthogonal channel for channel estimation, the PHT matrix is as follows:
Figure BDA0002874901190000062
Figure BDA0002874901190000063
the PHT matrix is based on the total number N of training sequences of dataLTFThe number is selected.
In order to reduce inter-stream interference, different cyclic shifts are designed for each stream in the time domain, and the cyclic shift in the time domain shows a constant phase rotation in the frequency domain, which is equivalent to multiplying each subcarrier by the same value exp (1j × θ)i),i＝1,…,Nsts,θiFor the phase rotation angle associated with each stream cyclic shift, 1j is an imaginary unit.
The data training sequence frequency domain rule of the known MIMO is synthesized as follows:
Figure BDA0002874901190000064
in contrast, as shown in fig. 1, this example provides a method for sorting streams of MIMO signals, including the following steps:
step S1, based on the long training sequence LTF, realizing frame synchronization to MIMO signal sliding correlation;
step S2, based on the frame synchronization result obtained in step S1, performing stream sequencing, wherein the stream sequencing is realized by performing header L of all streamsstart(i) According to the total number of received data streams NrAnd frame header L of each streamstart(i) Sorting the relation of magnitude, wherein i is a natural number and is used for representing a cyclic variable, such as a stream sorting sequence number of the MIMO signal, and the ith MIMO signal is also called as an MIMO signal stream i, an MIMO signal space-time stream i, an ith stream or a stream i; similarly, the ith receiving antenna may be referred to as a receiving antenna i for short, and the ith transmitting stream may be referred to as a transmitting stream i for short; since i represents only the sequence number of the cyclic variable, i.e., a natural number, and does not represent the MIMO signal and the receiving antenna itself;
step S3, calculating the carrier frequency offset of each data stream, and carrying out carrier frequency offset compensation on the whole stream signal;
step S4, realizing initial channel estimation based on long training sequence LTF;
step S5, analyzing frame system information based on initial channel estimation;
step S6, stream sorting is performed based on the data training sequence.
In step S1, the received time domain signal is assumed to be y (t) ═ yI(t)+j*yQ(t), t is 1, …, N, where N is the total number of sample points, yI(t) and yQ(t) respectively represents the real part and the imaginary part of the time domain signal at the time t, and j is an imaginary unit. x (t) ═ xI(t)+j*xQAnd (t), t is 1, …, M is the total number of sampling points of the local training sequence, and M is inevitably smaller than N. The correlation operation is defined as a correlation operation value
Figure BDA0002874901190000071
x(t1) For local training sequence x (t) with t ═ t1As the starting sequence, y (t)2) For receiving time-domain signals y (t) with t ═ t2Is the sequence to be started up in the sequence,
Figure BDA0002874901190000072
represents the mean value
Figure BDA0002874901190000073
Figure BDA0002874901190000074
Represents the mean value
Figure BDA0002874901190000075
In the synchronization process, a received time domain signal y (t) and a local known training sequence x (t) are used for carrying out sliding correlation operation to judge the similarity degree, and the specific operation is respectively carrying out cross correlation on IQ paths and taking the square accumulated value after the correlation.
Assuming that the correlation value at time t is denoted as c (t), c (t) is correl (y)I(t),xI(0))+correl(yI(t),xQ(0))+correl(yQ(t),xI(0))+correl(yQ(t),xQ(0))。
The process of implementing frame synchronization to MIMO signal sliding correlation based on long training sequence LTF is as follows: performing sliding correlation operation on an ideal time domain signal x (t) of a local known long training sequence LTF on a received time domain signal y (t), if x (t) exists on y (t), when sliding correlation is performed to a corresponding initial point, a sliding correlation operation value C (t) can generate a Peak value Peak (C (t)), and because the long training sequence LTF defined by a protocol is repeated twice, x (t) exists on y (t), two Peak values can be generated, and the Peak value can be marked as Peak (C (t)1)),Peak(C(t2)),t1,t2E t, and the time interval between two peaks, Δ τ (t)2-t1) Fs exactly fits in the period of 3.2us (microseconds) of the interval of the long training sequence LTF, where Fs is the sampling rate, then the position t where the first peak occurs is taken1As long training sequence LTF start position LLTF，t2The position where the second peak occurs.
In this example, the long training sequence LTF is used to obtain the start position L in step S1LTFDefining short and long training sequences according to the protocol, by the formula Lstart＝LLTFFrame header L after frame synchronization is obtained by 9.6us FsstartWhere us is the unit of time in microseconds and Fs is the sampling rate.
In step S2 in this example, the total number of received data streams is NrFor each received stream i, a frame header is calculated according to the method of step S1, and is marked as Lstart(i) In that respect The signal is designed at the transmitting end, and each data stream has different cyclic shifts, as shown in the following table:
Figure BDA0002874901190000081
according to the characteristic of cyclic shift, the frame head positions of the local training sequence and different receiving streams after synchronization are different, and the offset is
Figure BDA0002874901190000082
Where Fs is the sampling rate and is the rate,
Figure BDA0002874901190000083
is the amount in the table, NrIs the number of streams, itx is the stream number. E.g. NrThen the difference in frame header position between the two streams has the following relationship Lstart(1)-Lstart(2)＝Fs*(iTX(2,1)-iTX(2,2)) Fs 200 ns. Frame header L for all streamsstart(i) Number of streams NrAnd sorting according to the frame header size relation calculated by the table. After reordering, the frame header L of each stream of the received signalstart(i) Frame header of MIMO signal and reordered frame header L according to cyclic shift characteristicsstart(1) The standard is. E.g. Nr＝2，Fs＝120MHz，Lstart(1)＝1200，Lstart(2) 1224 where Lstart(1)>Lstart(2) To explain the exchange sequence, after exchange, Lstart(1)＝1224，Lstart(2) 1200, the MIMO signal frame header is changed to 1224.
Step S3 described in this example is used to compensate carrier frequency offset existing in the received signal, and first calculate carrier frequency offset of each data stream (this process belongs to general communication technology and can be implemented by the prior art), then calculate an average value, and then correspondingly compensate carrier frequency offset. This example uses the long training sequence LTF for frequency offset estimation, 11n, 11ac and 11ax comprise two repeated long training sequences, the duration of the repetition interval Δ t is 3.2us, the duration and interval samples M are Δ t Fs, the LTF start sample nltf＝(Lstart(1)+tstf+tGI_ltf) Fs, where Fs is the sampling rate, Lstart(1) For the frame header, t, obtained after step S2stf8us is the duration of the short training sequence STF, tGI_ltf1.6us is the duration of the LTF guard interval. The MIMO receiving time sequence signal is expressed as a receiving time domain signal of yi(t),i＝1,…,NrT is 1, …, N, where N isrN is the total sampling point of the MIMO signal reception for the total number of received signal streams.
Calculating an index
Figure BDA0002874901190000091
yi(t+nltf) For the ith stream t + n of the MIMO received signalltfComplex signal of a dot, yi(t+M+nltf) For the ith stream t + M + n of the MIMO received signalltfThe complex signal of the point or points is,
Figure BDA0002874901190000092
and accumulating after multiplying corresponding points, and solving the complex conjugate of the signal by using the superscript T.
In step S3 in this example, the formula is used
Figure BDA0002874901190000093
Calculating carrier frequency deviation type delta f of each data stream iltf(i)Then taking the average of the frequency offsets of all streams as
Figure BDA0002874901190000094
And by the formula
Figure BDA0002874901190000095
And carrying out carrier frequency offset compensation on the whole flow signal. Where Δ t is the repetition interval duration of the long training sequence LTF, Rltf(i)Calculating an intermediate index for the frequency offset of the MIMO signal stream i; y isi(t) is a complex signal representation of the MIMO signal stream i at time t; 1j is an imaginary unit; the compensation interval t belongs to [1N ]]N is a MIMO signalThe number receives the total sample point.
In this example, step S4 is to perform initial channel estimation based on the long training sequence LTF, and to perform channel estimation using the long training sequence LTF, so as to obtain channel states of the system messages HT-SIG, VHT-SIG, and HE-SIG.
In step S5, based on the initial channel estimation of LTF in step S4, the received system messages HT-SIG, VHT-SIG, and HE-SIG are equalized and corresponding demodulation and decoding are completed (this is the inverse process of the protocol definition at the transmitting end), and the fields of HT-SIG, VHT-SIG, and HE-SIG are analyzed according to the protocol definition to obtain the analytic messages of the signals, including the PHT matrix P used by the MIMO signal and the total number N of space-time streams of the signalstsThe total number of training sequences N of the signal dataLTFAnd space-time stream i carrier bearing state Ai,i＝1,…,NstsAnd MIMO signal stream i carrier bearing state Ai,i＝1,…,Nsts。
In step S6 in this example, the tester uses NrReceiving MIMO signals by the RF ports; the step S6 includes the following sub-steps:
step S601, for the ith receiving antenna, i is 1, …, NrEach data stream having NLTFPositioning the data training sequence to the time domain position of the data training sequence, transforming the data training sequence to the frequency domain through Fourier transform, and recording the j-th data training sequence frequency domain of the i-th receiving antenna as Yi,j＝[yi,j,1,yi,j,2,…,yi,j,K]TWherein N isrRepresenting the total number of streams received, yi,j,kRepresenting the subcarrier data of the ith receiving antenna on the jth data training sequence with the frequency domain serial number of k, wherein the superscript T is transposition, and j is a natural number and is used for representing the cyclic variable of a symbol; k is a natural number for representing a cyclic variable of the subcarrier;
step S602, calculating the correlation value of the data training sequence by formula
Figure BDA0002874901190000101
Calculating data training sequence correlation zi,jK is the total number of received data subcarriers, yi,j,kIndicating that the frequency domain sequence number of the ith receiving antenna on the jth data training sequence is equal to the subcarrier data on k, yi,1,kIndicating that the frequency domain serial number of the ith receiving antenna on the 1 st data training sequence is equal to the subcarrier data on k, that is, on the received MIMO signal stream i, the jth data training sequence and the 1 st data training sequence are divided point by point according to the subcarrier serial number k, and when j is 1, z is presenti,1＝1；
Step S603, calculating flow information through formula
Figure BDA0002874901190000102
Calculating flow information Ri,k,k∈[1Nsts]Wherein N isLTFFor the total number of training sequences, N, of the signal data parsed in step S5stsThe total number of space-time streams, P, of the signal analyzed in step S5i,jI row and j column of PHT matrix defined for protocol, Ai,kResolving the state of the carrying data of the ith sending flow on the subcarrier k for the step S5, and resolving the state A of the carrying data of the ith sending flow on the subcarrier ki,kData-carrying subcarrier a for shorti,k1 in the presence, 0 in the absence, Ni,AFor carrying data subcarrier Ai,kThe number of the carbon atoms is not 0. For a received MIMO signal stream i, R is comparedi,1To
Figure BDA0002874901190000103
Selecting the maximum value Ri,pP is the stream sequence number of the sending end, and p belongs to [1N ]sts]That is, the currently received MIMO signal stream i has a stream sequence number p corresponding to the transmitting end, and the principle is to use the autocorrelation value of the PHT matrix as NLTFThe cross-correlation value is 0;
step S604, determining whether reordering and processing are needed, and when i ≠ p exists, reordering the received streams according to the analyzed size of p, and after reordering, changing p to 1 and p to NstsThe stream enters the subsequent analysis, i is the stream sequencing serial number when the MIMO signal is received; p is a stream sequence number of the stream at the transmitting end when receiving the MIMO signal. If the order of streams transmitted by the DUT to the tester is chaotic, or the same stream transmit stream is transmitted over multiple antennasHowever, the received stream number i may not match the transmitted stream number, but the stream number p analyzed in step S603 must match the transmitted stream number. Said step S604 is for implementing reordering and processing, if i ═ p is available for all streams, then the stream ordering is normal; it should be noted that if there are multiple received streams i corresponding to the same p, which means there are two same transmitted streams, the processing is to only keep one entry sequence, and not enter the analysis processing after the entry.
After the flow ordering is completed, the remaining work is completed according to the conventional way of signal processing and the calculation index, which is consistent with the signal processing procedure of the prior art and will not be described further. FIG. 10 is a graph of data that is not sorted by stream in a line disorder, and the results of analyzing various indicators are abnormal; fig. 11 is an analysis result after stream ordering processing, as can be seen from a comparison between simulations in fig. 10 and fig. 11, when the stream ordering method for MIMO signals provided in this example is suitable for analyzing multiple data streams with a tester in an 802.11n/ac/ax standard MIMO scenario, a problem of analysis failure of the tester can be effectively solved, for example, a problem of failure caused by a wrong connection between a device to be tested and the tester or a problem of failure caused by a disordered space-time stream of a signal when the device to be tested transmits a beamforming signal is solved.
Through the embodiment, the tester can reorder the data stream according to the input signal characteristics, so that the stream sequence transmitted to the tester by the device to be tested is regular, after stream ordering is completed at the tester end, each index of the transmitted signal is successfully analyzed, the MIMO test complexity of the device to be tested is effectively reduced, and the test flexibility of the tester is improved. Therefore, after the test method is used, the problem of matching of the DUT antenna serial number and the tester RF serial number does not need to be considered in the MIMO signal test, the complexity of the MIMO signal test is reduced, and the test is more flexible.
This example also provides a MIMO signal stream ordering system, which adopts the above MIMO signal stream ordering method, and includes:
the frame synchronization module is used for realizing frame synchronization on the MIMO signal sliding correlation based on the long training sequence LTF;
flow ordering Module, basePerforming stream sequencing on the frame synchronization result obtained in step S1, wherein the stream sequencing is implemented by performing a process of performing header L on all streamsstart(i) According to the total number of received data streams NrAnd frame header Lstart(i) Sorting the relationship of the sizes;
the frequency offset estimation and compensation module is used for calculating the carrier frequency offset of each data stream and carrying out carrier frequency offset compensation on the whole stream signal;
the initial channel estimation module is used for realizing initial channel estimation based on the long training sequence LTF;
the system message analysis module analyzes the frame system message based on the initial channel estimation;
and the flow ordering module is used for carrying out flow ordering based on the data training sequence.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims (9)

1. A method for stream ordering of MIMO signals, comprising the steps of:
step S1, based on the long training sequence LTF, realizing frame synchronization to MIMO signal sliding correlation;
step S2, based on the frame synchronization result obtained in step S1, performing stream sequencing, wherein the stream sequencing is realized by performing header L of all streamsstart(i) According to the total number of received data streams NrAnd frame header L of each streamstart(i) Sorting the relation of magnitude, wherein i is the serial number of the receiving antenna;
step S3, calculating the carrier frequency offset of each data stream, and carrying out carrier frequency offset compensation on the whole stream signal;
step S4, realizing initial channel estimation based on long training sequence LTF;
step S5, analyzing frame system information based on initial channel estimation;
step S6, based on the data training sequence, making flow ordering,
the step S6 includes the following sub-steps:
step S601, for the ith receiving antenna, i is 1, …, NrEach data stream having NLTFPositioning the data training sequence to the time domain position of the data training sequence, transforming the data training sequence to the frequency domain through Fourier transform, and recording the j-th data training sequence frequency domain of the i-th receiving antenna as Yi,j＝[yi,j,1,yi,j，2,…,yi,j,K]TWherein N isrRepresenting the total number of streams received, yi,j,kRepresenting that the frequency domain serial number of the ith receiving antenna on the jth data training sequence is equal to subcarrier data on k, and superscript T is transposition; j is a natural number for representing a cyclic variable of the symbol; k is a natural number used for representing a cyclic variable of a subcarrier, and K is the total number of the received data subcarriers;
step S602, calculating a data training sequence correlation value;
step S603, calculating flow information;
step S604, determining whether reordering and processing are needed, and when i ≠ p exists, reordering the received streams according to the analyzed size of p, and after reordering, changing p to 1 and p to NstsThe stream enters the subsequent analysis, p is the stream sequencing serial number of the stream at the transmitting end when the MIMO signal is received, NstsIs the number of signal space-time streams.
2. The method of claim 1, wherein in step S1, the flow is ordered according to formula Lstart＝LLTFFrame header L after frame synchronization is obtained by 9.6us FsstartWhere us is the time unit microsecond, Fs is the sampling rate, LLTEIs the start position of the long training sequence LTF.
3. The method of claim 2, wherein the frame synchronization of the MIMO signal based on the long training sequence LTF by sliding correlation is performed by: ideal time domain signal x (t) of locally known long training sequence LTF on received time domain signal y (t)Performing sliding correlation operation, and searching two obvious Peak values Peak (C (t) in the correlation value C (t) of the sliding correlation operation1)),Peak(C(t2) And the time interval between two peaks, Δ τ ═ (t)2-t1) The interval period of Fs exactly conforming to the long training sequence LTF is 3.2us, then the position t where the first peak appears is taken1As long training sequence LTF start position LLTF，t2The position where the second peak occurs.
4. The method according to any of claims 1 to 3, wherein in step S2, if the stream sequence is not correct, according to a frame header Lstart(i) The streams are reordered according to a preset cyclic shift table, and after reordering, the frame headers L of the received streamsstart(i) Conforming to the cyclic shift characteristic, the frame header of the whole MIMO signal is re-sequenced with the frame header L after the re-sequencingstart(1) Is the new frame header position.
5. The method of claim 4, wherein in step S3, the MIMO signal stream is sequenced according to a formula
Figure FDA0003283640200000021
Calculating carrier frequency deviation type delta f of each data streamltf(i)Then taking the average of the frequency offsets of all streams as
Figure FDA0003283640200000022
And by the formula
Figure FDA0003283640200000023
Carrying out carrier frequency offset compensation on the whole flow signal; where Δ t is the repetition interval duration of the long training sequence LTF, Rltf(i)Calculating an intermediate index for the frequency offset of the MIMO signal stream i; y isi(t) is a complex signal representation of the MIMO signal stream i at time t; 1j is an imaginary unit; the compensation interval t is an element of [1, N ∈]And N is the total sampling point of the MIMO signal receiving.
6. The method as claimed in any one of claims 1 to 3, wherein in step S5, the fields of the received HT-SIG, VHT-SIG and HE-SIG are equalized based on the initial channel estimation, the fields of the HT-SIG, VHT-SIG and HE-SIG are analyzed according to the protocol definition, and the parsing message of the signal is obtained, which includes the PHT matrix P used by the MIMO signal, and the total number N of space-time streams of the signalstsThe total number of training sequences N of the signal dataLTFAnd MIMO signal stream i carrier bearing state Ai,i＝1,…,Nsts。
7. The method of any of claims 1-3, wherein in step S602, the MIMO signal stream is ordered according to a formula
Figure FDA0003283640200000024
Calculating data training sequence correlation zi,jK is the total number of received data subcarriers, yi，1,kAnd the data of the subcarrier with the frequency domain sequence number equal to k on the 1 st data training sequence of the ith receiving antenna is shown.
8. The method of any of claims 1-3, wherein in step S603, the MIMO signal stream is ordered according to a formula
Figure FDA0003283640200000025
Calculating flow information Ri,k,k∈[1,Nsts]Wherein N isLTFFor the total number of training sequences, N, of the signal data parsed in step S5stsThe total number of space-time streams, P, of the signal analyzed in step S5i,jDefining the ith row and the jth column of a PHT matrix for a protocol; a. thei，kAnalyzing the state of the carrier data of the ith sending stream on the kth subcarrier in step S5, which is called carrier data subcarrier a for shorti，kIf the signal exists, the signal is 1, and if the signal does not exist, the signal is 0; n is a radical ofi,AFor carrying data subcarrier Ai,kThe number of the carbon atoms is not 0.
9. A stream ordering system for MIMO signals, characterized in that the stream ordering method for MIMO signals according to any one of claims 1 to 8 is adopted, and comprises:
the frame synchronization module is used for realizing frame synchronization on the MIMO signal sliding correlation based on the long training sequence LTF;
a stream sequencing module for performing stream sequencing based on the frame synchronization result obtained in the step S1, wherein the stream sequencing is realized by performing frame header L of all streamsstart(i) According to the total number of received data streams NrAnd frame header Lstart(i) Sorting the relationship of the sizes;
the frequency offset estimation and compensation module is used for calculating the carrier frequency offset of each data stream and carrying out carrier frequency offset compensation on the whole stream signal;
the initial channel estimation module is used for realizing initial channel estimation based on the long training sequence LTF;
the system message analysis module analyzes the frame system message based on the initial channel estimation;
a flow ordering module for ordering the flow based on the data training sequence,
the processing method of the flow ordering module comprises the following sub-steps:
step S601, for the ith receiving antenna, i is 1, …, NrEach data stream having NLTFPositioning the data training sequence to the time domain position of the data training sequence, transforming the data training sequence to the frequency domain through Fourier transform, and recording the j-th data training sequence frequency domain of the i-th receiving antenna as Yi,j＝[yi,j,1,yi,j，2,…,yi,j,K]TWherein N isrRepresenting the total number of streams received, yi,j,kRepresenting that the frequency domain serial number of the ith receiving antenna on the jth data training sequence is equal to subcarrier data on k, and superscript T is transposition; j is a natural number for representing a cyclic variable of the symbol; k is a natural number used for representing a cyclic variable of a subcarrier, and K is the total number of the received data subcarriers;
step S602, calculating a data training sequence correlation value;
step S603, calculating flow information;
step S604, judging whether reordering and processing are neededWhen i ≠ p exists, reordering the received streams according to the analyzed size of p, and after reordering, setting p to 1 and setting p to NstsThe stream enters the subsequent analysis, p is the stream sequencing serial number of the stream at the transmitting end when the MIMO signal is received, NstsIs the number of signal space-time streams.
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