CN102651727B - Incoherence detection method used in spatial modulation-orthogonal frequency division multiplexing (SM-OFDM) system of a plurality of antennas - Google Patents

Abstract

The invention discloses an incoherence detection method used in a spatial modulation-orthogonal frequency division multiplexing (SM-OFDM) system of a plurality of antennas. According to the incoherence detection method provided by the invention, initialization matrixes are obtained through initializing non-zero subcarriers on each antenna at the emitting end, in addition, the initialization matrixes are combined with space modulation matrixes into space modulation signal matrixes, further, the differential coding is carried out on the non-zero subcarriers on each antenna, and continuously updated OFDM demodulation data in the front M moment is utilized for recovering bit stream information at the receiving end. The method provided by the invention has the advantages that the differential technology is applied to the SM-OFDM system, the method is suitable for the SM-OFDM system with a plurality of antennas, in addition, the channel estimation and the channel balance are not needed, and the complexity of the SM-OFDM system is effectively reduced.

Description

Be used for the incoherent detection method of the SM-OFDM system of many antennas

Technical field

The invention belongs to communication technical field, particularly a kind of incoherent detection method of the SM-OFDM system for many antennas.

Background technology

The spatial multiplexing gain of traditional multi-antenna technology depends on the orthogonality of transmitting antenna and reception antenna, a kind of new antenna technology spatial modulation (Spatial Modulation, SM) technology has been avoided intersymbol interference (Inter-Carrier Interference completely,, and do not require the orthogonality of transmitting antenna and reception antenna ICI).At transmitting terminal, bit information is mapped to accordingly on certain astrology point and special antenna and is sent, and at receiving terminal, according to receiving Signal estimation set out carry information and transmitting antenna sequence number, can recover transmission information completely.And spatial modulation is combined to (SM-OFDM) with OFDM technology, be used in multiple-input and multiple-output (Multiple Input Multiple Output by orthogonal frequency division multiplexing, MIMO) in system, frequency-selective channel is converted into flat fading channel, thereby realizes channel estimating and equilibrium.

The implementation complexity that during traditional relevant mimo system detects, channel estimating and carrier phase recovery bring and frequency spectrum expense are all much larger than conventional single-antenna communication system, and differential signal transmitting reception does not need channel information, also do not need phase-locked loop with the reinsertion of carrier, thereby simplify system realization, in SM-OFDM system, used incoherent detection method to have very large advantage.

2010, the people such as S.Sugiura are for the Novel MIM O system (STSK based on SM system extension, Space-Time Shift Keying) system proposes incoherent detection algorithm (referring to document: S.Sugiura, S.Chen, and L.Hanzo, " Coherent and differential space-time shift keying:a dispersion matrix approach, " IEEE Trans.Commun., vol.58, no.11, pp.3219-3230, Novermber2010), but this incoherent detection algorithm is only for some special STSK system, these STSK systems have a common feature: the disperse matrix of system is Hermitian matrix, and the disperse matrix of SM system is also mentioned in above-mentioned document, it is the matrix of one 1 dimension, it can not be Hermitian matrix, therefore above-mentioned incoherent algorithm is not suitable for SM system.

Summary of the invention

The object of the invention is to solve many antennas SM-OFDM system and cannot carry out the problem of incoherent detection, proposed a kind of incoherent detection method of the SM-OFDM system for many antennas.

Technical scheme of the present invention is: a kind of incoherent detection method of the SM-OFDM system for many antennas, specifically comprises the steps: at transmitting terminal

Step 1: first non-zero sub-carriers on every antenna of initialization obtains the initialization matrix of M × M dimension, be specially: j (j=1,2, ..., M) reference symbol on root antenna is positioned on j subcarrier of j root antenna, and to only have and have data, other antenna data on j root antenna be zero j moment, wherein, the number that M is transmitting antenna;

Step 2: to log ₂the incoming bit stream matrix of (M × L) × (N-M) carries out spatial modulation and obtains M × (N-M) spatial modulation matrix of dimension, and wherein, L is constellation order of modulation, and N is the number of every antenna previous frame OFDM symbol subcarrier;

Step 3: the spatial modulation matrix that the initialization matrix that step 1 is obtained and step 2 obtain combines the spatial modulation signal matrix that obtains M × N dimension, all subcarriers on the corresponding antenna of the every a line of spatial modulation signal matrix of described M × N dimension, non-zero sub-carriers on every antenna is carried out to differential coding, the subcarrier of the N after the differential coding on every antenna is carried out to OFDM modulation;

Specifically comprise the steps: at receiving terminal

Step 5: the data on every antenna are carried out to OFDM demodulation;

Step 6: utilize the OFDM demodulating data demodulation that step 5 obtains to recover original transmitted information bit sequence, detailed process is as follows:

Utilize the OFDM demodulating data in front M moment to detect the OFDM demodulating data in rear N-M moment, be specially:

Detection to the M+n moment is specially: utilize respectively the 1st, 2, the OFDM demodulating data in M moment detects the OFDM demodulating data in M+n moment, L that obtains each moment is detected data, and then obtain the front M moment all M × L and detect data, detect data and select minimum detection data corresponding moment and constellation symbol from M × L, the moment that utilization is selected and constellation symbol are carried out space demodulation and are recovered bit stream information, and utilize the data in the moment of the Data Update selection in current M+n moment; Start to repeat this process from n=1, until n=N-M.

Further, utilize respectively the 1st, 2 described in step 6 ..., the OFDM demodulating data in M moment detects concrete employing maximum likelihood algorithm to the OFDM demodulating data in M+n moment.

Beneficial effect of the present invention: incoherent detection method of the present invention obtains initialization matrix by the non-zero sub-carriers on every antenna of transmitting terminal initialization, and by itself and spatial modulation matrix group blended space modulation signal matrix, and then the non-zero sub-carriers on every antenna is carried out to differential coding, the OFDM demodulating data in the front M moment of constantly updating in receiving terminal utilization recovers bit stream information.Method of the present invention can be applied to differential technique SM-OFDM system, is suitable for the SM-OFDM system of many antennas, and does not need to carry out channel estimating and channel equalization, effectively reduces the complexity of SM-OFDM system.

Accompanying drawing explanation

Fig. 1 is incoherent detection method transmitting terminal schematic diagram of the present invention.

Fig. 2 is the spatial modulation mapping form schematic diagram of two transmit antennas.

Fig. 3 is incoherent detection method receiving terminal schematic diagram of the present invention.

Embodiment

Below in conjunction with accompanying drawing, provide specific embodiments of the invention.Setting forth before embodiment wherein term used of paper:

M represents the number of transmitting antenna, and R represents the number of reception antenna, and L is order of modulation, and N is the number of every antenna previous frame OFDM symbol subcarrier; Q is the binary bit stream matrix of P × (N-M), P=log ₂(M × L); U ∈ C ^{m × N-M}for the spatial modulation matrix of Q after spatial modulation, T ∈ C ^{m × M}for initialization matrix, S ∈ C ^{m × N}for spatial modulation signal matrix, formed by U and T matrix, front M × M dimension is T matrix, rear M × (N-M) dimension is U matrix.S _i(i=1,2 ..., M) and be that the i of S is capable, represent the vector that all subcarriers on i root antenna form, S _i(l) be S _il non-zero sub-carriers; X ∈ C ^{m × N}for the non-zero element of the every row of S is carried out to the difference matrix that differential coding obtains, the non-zero sub-carriers on every root antenna is carried out to the matrix obtaining after differential coding, X _ifor the i of X is capable, represent N the vector that subcarrier forms after differential coding on i root antenna, X _i(l) represent X _il non-zero sub-carriers, the character from spatial modulation: each row of matrix S and X all only have a nonzero element; Transmission matrix X (m) ∈ C ^{m × 1}, (m=1,2 ..., N) represent that the m of X is listed as, i.e. the transmitting vector in m moment; Y ∈ C ^{r × N}, represent the receiving matrix after OFDM demodulation on every antenna, Y (m) ∈ C ^{r × 1}represent the m row of Y, i.e. the reception vector in m moment; H (m) ∈ C ^{r × M}and V (m) ∈ C ^{r × 1}refer to respectively channel coefficients and the 0 average Gaussian noise in m moment, wherein suppose that adjacent channel coefficients is similar to constant H (m) ≈ H (m-1), wherein, H _k(m) k of expression H (m) row.

First the course of work that the present invention is proposed to SM-OFDM incoherent detection system describes, and specific works principle is as Fig. 1, and Fig. 2 and Fig. 3 represent.

At transmitting terminal, the non-zero sub-carriers on every antenna is carried out to initialization, first non-zero sub-carriers of j root antenna is positioned on j subcarrier of this antenna; After first non-zero sub-carriers on initial complete every antenna, start to carry out spatial modulation, every P bit shines upon, front log ₂(M) bit is selected antenna, remaining log ₂(L) bit carries out after L-PSK modulation by the antenna transmission of selecting; Then the non-zero sub-carriers on every antenna is carried out to differential coding, after coding, carry out OFDM modulate emission and go out.

Fig. 2 is the spatial modulation mapping form of two antennas, P=3, and M=2, L=4,1 bit is selected antenna, and 2 bits are selected constellation symbol, and by the antenna transmission of selecting.

Very approaching for receiving terminal hypothesis adjacent channel coefficient, receiver carries out the data that receive after OFDM demodulation, utilizes initialized data characteristic to carry out maximum likelihood (Maximum Likelihood, ML) demodulation.

Specifically be unfolded as follows:

Specifically comprise the steps: at transmitting terminal

Step 1: first non-zero sub-carriers on every antenna of initialization obtains the initialization matrix T of M × M dimension, be specially: j (j=1,2, ..., M) reference symbol on root antenna is positioned on j subcarrier of j root antenna, to only have and have data, other antenna data on j root antenna be zero j moment;

Step 2: to log ₂the incoming bit stream matrix of (M × L) × (N-M) carries out spatial modulation and obtains M × (N-M) spatial modulation matrix U of dimension;

Step 3: the spatial modulation matrix U that the initialization matrix T that step 1 is obtained and step 2 obtain combines the spatial modulation signal matrix S that obtains M × N dimension, all subcarriers on the corresponding antenna of the every a line of spatial modulation signal matrix of described M × N dimension, non-zero sub-carriers on every antenna is carried out to differential coding, the subcarrier of the N after the differential coding on every antenna is carried out to OFDM modulation;

X _i(l)=X _i(l-1)S _i(l),(1<l<N);X _i(1)=S _i(1);

Specifically comprise the steps: at receiving terminal

Step 4: system is through Rayleigh and Gaussian channel;

Step 5: the data on every antenna are carried out obtaining R × N dimension receiving matrix Y after OFDM demodulation;

Step 6: utilize the OFDM demodulating data demodulation that step 5 obtains to recover original transmitted information bit sequence, detailed process is as follows:

(6.1) for the reception data in the 1st to M moment, the antenna index of the reception data in m moment is m.

Y (m) is the reception vector in m moment, and due to initialized particularity and SM-OFDM system, due to the characteristic of OFDM, receiving data can be expressed as follows:

Y(m)=H(m)X(m)+V(m)；

Because initialized matrix is very special, thus for the transmitting data in front M moment: X (m)=(0 ..., X _m(1) ..., 0) ^t,

Y (m)=H _m(m) ⊙ X _m(1)+V (m), wherein, ⊙ represents dot product.

Therefore, for the reception data in the 1st to M moment, the antenna index of the reception data in m moment is m, after testing process in, the data in the 1st to M moment are constantly updated as the reference symbol in whole testing process.

(6.2) utilize for the 1st to M moment receive the known antenna index of data and detect the antenna index value and the constellation symbol that receive data below.

Transmitting data for the rear N-M moment: X (m)=(0 ..., X _k(l) ..., 0) ^t,

Y (m)=H _k(m) ⊙ X _k(l)+V (m), represents to receive data from k transmit antennas;

Y (m-1)=H _q(m-1) ⊙ X _q(l ')+V (m-1), represent to receive data from q transmit antennas;

X _k(l)=X _k(l-1)S _k(l)；

Y(m)=Y(k)⊙S _k(l)+N(m),k=1,2,…,M；

N(m)≈V(k)⊙S _k(l)+V(m)。

Utilize the OFDM demodulating data in front M moment to detect the OFDM demodulating data in rear N-M moment, be specially:

Detection to the M+n moment is specially: utilize respectively the 1st, 2, the OFDM demodulating data in M moment detects the OFDM demodulating data in M+n moment, L that obtains each moment is detected data, and then obtain the front M moment all M × L and detect data, detect from M × L corresponding moment and the constellation symbol of detection data of selecting 2 Norm minimums data, the moment that utilization is selected and constellation symbol are carried out space demodulation and are recovered bit stream information, and utilize the data in the moment of the Data Update selection in current M+n moment; Start to repeat this process from n=1, until n=N-M.

Here, utilize respectively the 1st, 2 described in step 6 ..., the OFDM demodulating data in M moment detects concrete employing maximum likelihood algorithm to the OFDM demodulating data in M+n moment.For the ease of understanding said process, provide following false code at this:

for?i=M+1:N

for?j=1:M

$(\hat{j},\hat{s})=\arg \underset{s\&Element;C^{(1,L)}}{\underset{j\&Element;(1,M)}{\min }}\left|\right|Y\left(i\right)-Y\left(j\right)*s\left|\right|$

$Y\left(\hat{j}\right)=Y\left(i\right)$

end

end

Wherein, s is L-PSK constellation symbol.

By detecting

can learn the antenna index value in this moment, this reception data vector of reception data representation that then upgrades the corresponding moment is mainly from the

nearest non-zero sub-carriers on transmitting antenna.

Incoherent detection method of the present invention obtains initialization matrix by the non-zero sub-carriers on every antenna of transmitting terminal initialization, and by itself and spatial modulation matrix group blended space modulation signal matrix, and then the non-zero sub-carriers on every antenna is carried out to differential coding, the OFDM demodulating data in the front M moment of constantly updating in receiving terminal utilization recovers bit stream information.Method of the present invention can be applied to differential technique SM-OFDM system, is suitable for the SM-OFDM system of many antennas, and does not need to carry out channel estimating and channel equalization, effectively reduces the complexity of SM-OFDM system.Method of the present invention does not limit transmitting antenna and reception antenna, has solved many antennas SM-OFDM system and cannot carry out the problem of incoherent detection.

Those of ordinary skill in the art will appreciate that, embodiment described here is in order to help reader understanding's principle of the present invention, should be understood to that protection scope of the present invention is not limited to such special statement and embodiment.Those of ordinary skill in the art can make various other various concrete distortion and combinations that do not depart from essence of the present invention according to these technology enlightenments disclosed by the invention, and these distortion and combination are still in protection scope of the present invention.

Claims (2)

1. for an incoherent detection method for the spatial modulation ofdm system of many antennas, specifically comprise the steps: at transmitting terminal

Step 1: first non-zero sub-carriers on every antenna of initialization obtains the initialization matrix of M × M dimension, be specially: j (j=1,2, ..., M) reference symbol on root antenna is positioned on j subcarrier of j root antenna, and to only have and have data, other antenna data on j root antenna be zero j moment, wherein, the number that M is transmitting antenna;

Step 2: to log ₂the incoming bit stream matrix of (M × L) × (N-M) carries out spatial modulation and obtains M × (N-M) spatial modulation matrix of dimension, and wherein, L is constellation order of modulation, and N is the number of every antenna previous frame OFDM symbol subcarrier;

Step 3: the spatial modulation matrix that the initialization matrix that step 1 is obtained and step 2 obtain combines the spatial modulation signal matrix that obtains M × N dimension, all subcarriers on the corresponding antenna of the every a line of spatial modulation signal matrix of described M × N dimension, non-zero sub-carriers on every antenna is carried out to differential coding, the subcarrier of the N after the differential coding on every antenna is carried out to OFDM modulation;

Specifically comprise the steps: at receiving terminal

Step 5: the data on every antenna are carried out to OFDM demodulation;

Step 6: utilize the OFDM demodulating data demodulation that step 5 obtains to recover original transmitted information bit sequence, detailed process is as follows:

Utilize the OFDM demodulating data in front M moment to detect the OFDM demodulating data in rear N-M moment, be specially:

Detection to the M+n moment is specially: utilize respectively the 1st, 2, the OFDM demodulating data in M moment detects the OFDM demodulating data in M+n moment, L that obtains each moment is detected data, and then obtain the front M moment all M × L and detect data, detect data and select minimum detection data corresponding moment and constellation symbol from M × L, the moment that utilization is selected and constellation symbol are carried out space demodulation and are recovered bit stream information, and utilize the data in the moment of the Data Update selection in current M+n moment; Start to repeat this process from n=1, until n=N-M.

2. incoherent detection method according to claim 1, is characterized in that, utilizes respectively the 1st, 2 described in step 6 ..., the OFDM demodulating data in M moment detects concrete employing maximum likelihood algorithm to the OFDM demodulating data in M+n moment.

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