CN101631002B - MIMO space-time encoding and decoding system and method without need of channel information - Google Patents

Abstract

The invention provides an MIMO space-time encoding and decoding system without the need of channel information, and the system comprises 2-fat one received and 2-fat two received MIMO space-time encoding and decoding functions and can realize the time-space decoding of an MIMO receiver without the need of channel information or channel estimation or a complicated channel estimation sub-system. The MIMO time-space encoding and decoding system without the need of the channel information reduces the complexity of the system and the realization cost of the system, thereby being widely applied in wireless local area networks and wireless metropolitan area networks and improving utilization rate of a wireless frequency spectrum and data transmission rate.

Description

A kind of MIMO space-time coding/decoding System and method for that need not channel information

Technical field

The present invention relates to multiple-input and multiple-output (MIMO) wireless communication technology field, particularly MIMO baseband modulation and demodulation techniques.

Background technology

In the existing mimo wireless communication technology, definite channel information need be known by 21 receipts and 22 receipts MIMO space-time coding/decoding systems, needs receiver that space channel is carried out parameter Estimation, and this makes that the realization of MIMO receiver is complicated, and cost is high.

MIMO transmit diversity and Space-Time Block Coding are settled a plurality of antennas and are adopted space-time block code because realization is simple relatively in the base station, receiver can obtain space diversity gain in wireless fading channel, and space-time block code has been included a plurality of wireless communication standards in.Alamouti is at " Alamouti S M; ' A Simple TransmitDiversity Technique for Wireless Communications " ' IEEE J Select AreasCommunication; Oct 1998; 16, pp1451-1458 " in the simple transmit diversity techniques of 2 transmitting antennas of a kind of employing has been proposed, and the notion of the simplest 2 antennas Space-Time Block Coding-Alamouti sign indicating number has been proposed formally.

People such as Tarokh are at (Tarokh V, Jafarkhani H, and Calderbank A, " Space-timeblock codes from orthogonal designs ", IEEE Trans.Inf.Theory, vol.45, no.5, pp.1456-1467, Jul.1999; Tarokh V; Jafarkhani H, CalderbankA, " Space-time Block Coding for Wireless Communications:PerformanceResults "; IEEE Journal on Selected Areas in Communications; Vol.17, No.3, March 1999; Tarokh V, Naguib A, Seshadri N; And Calderbank A, " Space-timecodes for high data rate wireless communication:performance criteriain the presence of channel estimation errors, mobility; and multiplepaths ", IEEE Trans.Commune., vol.47; No.2, pp.199-207, Feb.1999; And, Tarokh V, Naguib A; Seshadri N, " Combined Array Processing and spacetime Coding ", IEEE Trans.on Communication info Theory; Vol.45, No4, MAY 1999) etc. in; It further is generalized to the situation more than two antennas, and proposes the notion of Space-Time Block Coding (STBC).Space-Time Block Coding comes down to a kind of spatial domain and time domain combined quadrature block encoding mode, and it utilizes the principle of orthogonal design to distribute transmitting of a plurality of transmitting antennas.Because Space-Time Block Coding obtains the full diversity gain after can making receiver decoding; Guarantee that decoding operation only is simple linear the merging; And its decoding complex degree is much lower with respect to existing space-time trellis codes; Therefore, Space-Time Block Coding has become the space-time coding/decoding technology that haves a great attraction in the practical application.

Because the Space Time Coding device need utilize time and space bidimensional to encode simultaneously, effective need of work of Space Time Coding device uses a plurality of antennas at transmitting terminal and receiving terminal, with effective counteracting decline, improves power efficiency; And then can in transmission channel, realize parallel multiplex, improve spectrum efficiency.Need to prove; Because the Space Time Coding technology belongs to space diversity signal processing category; So require under the multichannel decline situation of multiple scattering body, to use; A plurality of antennas of transmitter and the distance between the receiver antenna should transmit, receive the signal mutual independence with assurance greater than 10 times the wavelength that transmits, and make full use of the multichannel decline that the multiple scattering body is caused.

The correlation in Space Time Coding introducing time and space in the signal that different antennae is sent just can be receiving terminal unexistent diversity gain of single-antenna wireless communication system and the coding gain that does not adopt Space Time Coding is provided thereby need not sacrifice bandwidth.

The basic functional principle of Space Time Coding is following: the inter-area traffic interarea that provides from information source; After arriving the Space Time Coding device; Form the modulation symbol of launching from a plurality of transmitting antennas simultaneously, vector symbol (STVS) when these modulation symbols are called space-time symbol (STS) or sky with vector output.The system of Space Time Coding realizes that block diagram is as shown in Figure 1.

Lattice encoding and space-time block code (STBC) when the Space Time Coding mode that proposes at present mainly contains demixing time space, sky.These three kinds of Space Time Coding respectively have its pluses and minuses; Can select suitable coding according to certain conditions; Because that in IEEE 802.16e agreement, adopted is Space-Time Block Coding (STBC); So emphasis is analyzed Space-Time Block Coding, point out the problem of its existence, and then propose 21 receipts and 22 receipts MIMO machine space-time coding/decoding systems that need not channel information of the present invention.

Coding method by Alamouti proposition STBC is the coding method that is fit to two system of transmit antennas at first, and on this basis, Tarokh extends to plural system of transmit antennas with it.Identical with the Alamouti coding method, Tarokh still adopts the encoder matrix of orthogonal design; Yet,, but can obtain maximum diversity gain no matter be that Alamouti or the coded system of Tarokh all can not obtain coding gain.Fig. 2 has provided the theory diagram of Alamouti STBC code coder.The Space-Time Block Coding that proposes with Alamouti below is an example, introduces the coding method of quadrature STBC.

Suppose with having 2 ^bThe planisphere of individual constellation point is modulated, and in encoding operation each time, one group of 2b information bit is mapped to signal constellation (in digital modulation), to select 2 modulation signal x ₁And x ₂With the Space Time Coding device 2 modulation signals are encoded, according to Alamouti Space-Time Block Coding encoder matrix

${\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">G</figure-callout>}}_2=\left[\begin{array}{cc}{x}_1& x_2\\ -x_2^{*}& x_1^{*}\end{array}\right]---\left(1a\right)$

Generate two length and be 2 parallel sequence.These two parallel sequences were launched through 2 antennas in 2 time cycles: in first cycle, and signal x ₁And x ₂Launch respectively from antenna 1 and 2 simultaneously; In second symbol period, signal-x ₂ ^*And x ₁ ^*Launch wherein () simultaneously respectively from antenna 1 and 2 ^*Conjugation is got in expression.

In general, STBC is by a p * N _TTransmission matrix G define N wherein _TBe number of transmit antennas, p is for sending the required symbol period number of a group code.Suppose with having 2 ^bThe planisphere of individual constellation point is modulated, and in encoding operation each time, the individual information bit of one group of kb (for Alamouti coding k=2) is mapped to signal constellation (in digital modulation), to select k modulation signal x ₁, x ₂..., x _kThe STBC encoder is encoded to this k modulation signal, generates N according to transmission matrix G _TIndividual length is the parallel signal sequences of p, and these sequences are passed through N _TTransmit antennas is launched in p symbol period; In other words, for every group of k incoming symbol, every antenna will send p space-time symbol.The code check of STBC is defined as the ratio between the Space Time Coding symbolic number that symbolic number that encoder extracts in when input and antenna launch, and can be expressed as:

R＝k/p (2)

For the Alamouti coding, so p=k=2 is its code check R=1.

Encoder matrix G ₂Characteristic:

$G_2^{\mathrm{<figure-callout\; id="2"\; label="H\; G"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">H</figure-callout>}}{G}_{}{}_2={\mathrm{\&rho;}}_2{I}_2---\left(3\right)$

Wherein, ${\mathrm{\&rho;}}_2=\underset{i=1}{\overset{2}{\mathrm{\&Sigma;}}}{\left|x_i\right|}^2,$ I ₂The unit matrix of expression 2 * 2.

More generally, respectively be listed as mutually orthogonal space-time block code in the launching code matrix and be called the orthogonal space time group coding, can get the design criterion of the encoder matrix G of orthogonal space time group coding by this definition; Alamouti " Alamouti S M; ' and Oct 1998; 16, pp1451-1458 for A Simple Transmit Diversity Technique for WirelessCommunications ', IEEE J Select Areas Communication " in detailed introduction is arranged.

Two row that encoder matrix G is inequality arbitrarily, its inner product is zero, or is expressed as:

$G^{H}G={\mathrm{\&rho;}}_p{I}_{N_T}---\left(4\right)$

Wherein ${\mathrm{\&rho;}}_p=\underset{i=1}{\overset{p}{\mathrm{\&Sigma;}}}{\left|x_i\right|}^2,$

Expression N _T* N _TUnit matrix.

Obviously, the emission diversity scheme G of Alamouti ₂Be quadrature STBC sign indicating number, as number of transmit antennas N _TA special case of=2 o'clock.The essence of quadrature STBC design is the orthogonality of launching code matrix, and this orthogonality is embodied in spatial domain and time-domain simultaneously.Utilize orthogonal design, can also design other quadrature STB sign indicating number.

No matter which kind of form encoder matrix is, the decoding of space-time block code all is to utilize its orthogonality, generally all adopts maximum likelihood decoding algorithm.

Receiving terminal adopts a reception antenna, and Alamouti scheme receiver principle block diagram is as shown in Figure 4.Constantly use h respectively to the channel fading coefficient of reception antenna at t from antenna 1 and 2 ₁(t) and h ₂(t) expression.Suppose that fading coefficients is constant between two continuous symbol transmit cycles, then can be expressed as

$h_1\left(t\right)=h_1(t+T)=h_1=\left|h_1\right|e^{j{\mathrm{\&theta;}}_1}---\left(5a\right)$

$h_2\left(t\right)=h_2(t+T)=h_2=\left|h_2\right|e^{j{\mathrm{\&theta;}}_2}---\left(5b\right)$

Wherein, | h _i| and θ _i(i=1,2) are respectively amplitude gain and the phase shift of transmitting antenna i to reception antenna, and T is a symbol period.

At the reception antenna end, then corresponding received signal can be expressed as at t and t+T constantly:

r ₁＝r(t)＝h ₁x ₁+h ₂x ₂+n ₁ (6a)

$r_2=r(t+T)=h_1{x}_2^{*}+h_2{x}_1^{*}+n_2---\left(6b\right)$

Wherein, n ₁And n ₂Be illustrated respectively in the sampling of the channel additive Gaussian noise that t and t+T receive constantly, the two is independent identically distributed complex random variable, and its average is zero, power spectral density is N ₀/ 2.

Definition acknowledge(ment) signal vector $r=[{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">r</figure-callout>}}_1,{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">r</figure-callout>}}_2^{*}],$ Coding vector x=[x ₁, x ₂] ^T, noise vector n=[n ₁, n ₂] ^T, then receive signal and can be rewritten into matrix form:

r＝Hx+n (7)

Wherein, H is a channel matrix.

$H=\left[\begin{array}{cc}{h}_1& h_2\\ h_2^{*}& -h_1^{*}\end{array}\right]---\left(8\right)$

Prove that easily H is an orthogonal matrix, promptly $H=\underset{i=1}{\overset{2}{\mathrm{\&Sigma;}}}{\left|h_i\right|}^2{\mathrm{<figure-callout\; id="2"\; label="I"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">I</figure-callout>}}_2.$ Because the orthogonality of orthogonal space time packet encoder matrix makes channel matrix also have orthogonality, this is a key property of orthogonal space time packet, has simplified its decode procedure greatly.

But the receiver of Alamouti scheme requires to obtain fully the channel fading coefficient h ₁And h ₂, its decoder need adopt the channel fading coefficient h ₁And h ₂Decode.Suppose that all signals all are equiprobable in the modulation constellation; Maximum likelihood decoder is to all possible

and

value, and the distance measure below a pair of signal of selection

makes from the signal modulation constellation is minimum:

$d^2(r_1,h_1{\hat{x}}_1+h_2{\hat{x}}_2)+d^2(r_2,-h_1{\hat{x}}_1^{*}+{\hat{h}}_2{\hat{x}}_1^{*})={|r_1-h_1{\hat{x}}_1-h_2{\hat{x}}_2|}^2+{|r_2+h_1{\hat{x}}_1^{*}-{\hat{h}}_2{\hat{x}}_1^{*}|}^2---\left(9\right)$

Channel matrix formula (8) substitution is received the signal formula, and maximum likelihood decoding can be expressed as:

$({\hat{x}}_1,{\hat{x}}_2)=\arg \underset{({\hat{x}}_1,{\hat{x}}_2)\&Element;C}{\min }({\left|h_1\right|}^2+{\left|h_2\right|}^2-1)({\left|{\hat{x}}_1\right|}^2+{\left|{\hat{x}}_2\right|}^2)+d^2({\tilde{x}}_1,{\hat{x}}_1)+d^2({\tilde{x}}_2,{\hat{x}}_2)---\left(10\right)$

Wherein C be modulation symbol to

all possible set, and

is through merge receiving two decision statistic that signal and CSI structure produces:

${\tilde{x}}_1=h_1^{*}{r}_1+h_2{r}_2^{*}---\left(11a\right)$

${\tilde{x}}_2=h_2^{*}{r}_1+h_1{r}_2^{*}---\left(11b\right)$

Order $\tilde{x}=[{\tilde{x}}_1,{\tilde{x}}_2],$ Have

$\tilde{x}=H^{H}r---\left(12\right)$

With the r=Hx+n substitution wherein, have

$\tilde{x}=H^H(\mathrm{Hx}+n)=\underset{i=1}{\overset{2}{\mathrm{\&Sigma;}}}{\left|h_i\right|}^{2}x+\mathrm{Hn}---\left(13\right)$

This shows that Alamouti scheme receiver need be known definite channel information, need receiver that space channel is carried out parameter Estimation, this makes that the realization of MIMO receiver is complicated, and cost is high.

Existing 21 receipts and 22 receipts MIMO space-time coding/decoding systems all need receiver to know definite channel information; All need receiver that space channel is carried out parameter Estimation; This makes that the realization of MIMO receiver is complicated, and cost is high, and this realization for the MIMO travelling carriage is very difficult.

Summary of the invention

For solving the problem that existing MIMO space-time coding/decoding technology exists; The present invention proposes need not 21 receipts and 22 receipts MIMO space-time coding/decoding systems of channel estimating and channel information; The coding/decoding system that proposes according to the present invention; When the MIMO receiver is decoded, do not need channel information when carrying out sky, and then do not need complicated channel estimating subsystem.The technical solution adopted for the present invention to solve the technical problems is:

A kind of 21 of need not channel information receive MIMO machine space-time coding/decoding system, and it comprises: encoder-side, single antenna receiver.Wherein, encoder-side is made up of information source, modulator, encoder, transmitting antenna 1 and transmitting antenna 2; The single antenna receiver comprises: reception antenna, the last branch road that has access to buffer, the following branch road that has access to electronic switch, signal combiner and a decision device 1, decision device 2.

The information bit that information source transmits is sent into encoder and is carried out encoding process after modulators modulate, after encoder encodes, launched by transmitting antenna 1 and transmitting antenna 2; The receiver end reception antenna receives transmitting antenna 1 signal to be decoded that 2 emissions come with transmitting antenna; The reception signal of last time slot is buffered through the buffer of last branch road; Branch road electronic switch closes under one time slot of back; The reception signal calculates through the reception signal combination that following branch road is sent into last time slot in signal combiner and the buffer, and signal combiner result of calculation is sent into decision device 1 and decision device 2 decoded signals, the decoded information bit after obtaining diversity gain and carrying out noise cancellation respectively.

A kind of 21 of need not channel information receive MIMO machine space-time coding/decoding method, and this method comprises:

In the step 1 modulating-coding stage, at first hypothesis is with having 2 ^bThe planisphere of individual constellation point is modulated, and in encoding operation each time, one group of 2b information bit is mapped to signal constellation (in digital modulation), to select 2 modulation signal x ₁And x ₂, with the Space Time Coding device 2 modulation signals are encoded, according to the Space-Time Block Coding encoder matrix

${\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">G</figure-callout>}}_2=\left[\begin{array}{cc}{x}_1& x_1\\ x_2& -x_2\end{array}\right]---\left(1b\right)$

Thereby generate 2 length and be 2 parallel sequence.

Step 2 launching phase, the parallel sequence behind the modulating-coding in the step was launched through 2 antennas in 2 time cycles: at first time slot, signal x ₁And x ₂Launch respectively from antenna 1 and 2 simultaneously; At second time slot, signal x ₁With-x ₂Launch respectively from antenna 1 and 2 simultaneously.

In the step 3 reception stage, reception antenna is responsible for receiving the signal of transmission antennas transmit, receives signal accordingly and is shown at t and t+T timetable:

r ₁＝r(t)＝h ₁x ₁+h ₂x ₂+n ₁ (6a)

r ₂＝r(t+T)＝h ₁x ₁-h ₂x ₂+n ₂ (6b)

Wherein, n ₁And n ₂Be illustrated respectively in the channel additive Gaussian noise that t and t+T receive constantly, the two is independent identically distributed complex random variable, and its average is zero, power spectral density is N ₀/ 2.

The step 4 combination calculation stage, one of which, the 1st time slot, receiving signal r (t) is r at the 1st time slot ₁, r ₁Through last branch road buffer memory in buffer, this at present the electronic switch of branch road open r ₁Can not pass through branch road down; Its two, the 2 time slot, receiving signal r (t) is r at the 2nd time slot ₂, the 2nd time slot is the electronic switch closes of branch road at present, r ₂R through following branch road entering signal combiner and buffer memory ₁Carry out combination calculation, order

z ₁＝r ₁+r ₂ (14a)

z ₂＝r ₁-r ₂ (14b)

Accomplish combination calculation by signal combiner according to last two formulas, and export combination calculation z as a result ₁And z ₂

Step 5 is used decision device and is carried out decode phase, order

x ₁＝a ₁+jb ₁，a ₁，b ₁∈{0，1}

x ₂＝a ₂+jb ₂，a ₂，b ₂∈{0，1}

Combination calculation is z as a result ₁And z ₂Through the decision device decoding, obtain x ₁And x ₂As follows:

$\mathrm{Re}{\hat{x}}_1=\mathrm{Sign}\left[\mathrm{Re}{z}_1\right]---\left(15a\right)$

$\mathrm{Im}{\hat{x}}_1=\mathrm{Sign}\left[\mathrm{Im}{z}_1\right]---\left(15b\right)$

$\mathrm{Re}{\hat{x}}_2=\mathrm{Sign}\left[\mathrm{Re}{z}_2\right]---\left(15c\right)$

$\mathrm{Im}{\hat{x}}_2=\mathrm{Sign}\left[\mathrm{Im}{z}_2\right]---\left(15d\right)$

Receive MIMO machine space-time coding/decoding system for a kind of 22, it comprises: encoder-side and single antenna receiver.Wherein, encoder-side is made up of information source, modulator, encoder, transmitting antenna 1 and transmitting antenna 2; The single antenna receiver comprises: reception antenna 1, reception antenna 2, the last branch road that has access to buffer, the following branch road that has access to electronic switch, signal combiner and decision device 1, decision device 2.

The information bit that information source transmits is sent into encoder and is carried out encoding process after modulators modulate, after encoder encodes, by transmitting antenna 1 and transmitting antenna 2 code signal is launched; Receiver end reception antenna 1 receives transmitting antenna 1 signal to be decoded that 2 emissions come with transmitting antenna respectively with reception antenna 2; The reception signal of last time slot is buffered through the buffer of last branch road; When the reception signal of back one time slot arrives at; Following branch road electronic switch closes, the reception signal calculates through the reception signal combination that following branch road is sent into last time slot in signal combiner and the buffer, and signal combiner result of calculation is sent into decision device 1 and decision device 2 respectively; After decision device 1 and decision device are decoded, the decoded information after obtaining diversity gain and carrying out noise cancellation.

A kind of 22 of need not channel information receive MIMO machine space-time coding/decoding method, and this method comprises:

In the step 1 modulating-coding stage, at first hypothesis is with having 2 ^bThe planisphere of individual constellation point is modulated, and in encoding operation each time, one group of 2b information bit is mapped to signal constellation (in digital modulation), to select 2 modulation signal x ₁And x ₂, with the Space Time Coding device 2 modulation signals are encoded, according to 2 length of Space-Time Block Coding encoder matrix (1b) generation 2 parallel sequence.

Step 2 launching phase, the parallel sequence behind the modulating-coding in the step was launched through 2 antennas in 2 time cycles: at the 1st time slot, signal x ₁And x ₂Launch respectively from antenna 1 and 2 simultaneously; At the 2nd time slot, signal x ₁With-x ₂Launch respectively from antenna 1 and 2 simultaneously.

In the step 3 reception stage, reception antenna is responsible for receiving the signal of transmission antennas transmit, receives signal accordingly and is shown at t and t+T timetable:

$\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]=\left[\begin{array}{cc}{h}_{11}& h_{12}\\ h_{21}& h_{22}\end{array}\right]\left[\begin{array}{c}{x}_1\\ x_2\end{array}\right]+\left[\begin{array}{c}{n}_1^{\left(1\right)}\\ n_2^{\left(1\right)}\end{array}\right]---\left(16a\right)$

$\left[\begin{array}{c}{r}_1^{\left(2\right)}\\ r_2^{\left(2\right)}\end{array}\right]=\left[\begin{array}{cc}{h}_{11}& -h_{12}\\ h_{21}& -h_{22}\end{array}\right]\left[\begin{array}{c}{x}_1\\ x_2\end{array}\right]+\left[\begin{array}{c}{n}_1^{\left(2\right)}\\ n_2^{\left(2\right)}\end{array}\right]---\left(16b\right)$

N wherein ₁ ⁽¹⁾And n ₂ ⁽¹⁾, n ₁ ⁽²⁾And n ₂ ⁽²⁾Be illustrated respectively in the channel additive Gaussian noise that t and t+T receive constantly, they are independent identically distributed complex random variable, and its average is zero, power spectral density is N ₀/ 2.

The step 4 combination calculation stage, one of which, the 1st time slot, reception signal r (t) at the 1st time slot does $\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right],\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]$ Through last branch road buffer memory in buffer, this at present the electronic switch of branch road open, $\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]$ Can not pass through branch road down; Its two, the 2 time slot, reception signal r (t) at the 2nd time slot does $\left[\begin{array}{c}{r}_1^{\left(2\right)}\\ r_2^{\left(2\right)}\end{array}\right],$ The 2nd time slot is the electronic switch closes of branch road at present, $\left[\begin{array}{c}{r}_1^{\left(2\right)}\\ r_2^{\left(2\right)}\end{array}\right]$ Through down branch road entering signal combiner and buffer memory $\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]$ Carry out combination calculation, order

$\left[\begin{array}{c}{r}_1^a\\ r_2^a\end{array}\right]=\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]+\left[\begin{array}{c}{r}_1^{\left(2\right)}\\ r_2^{\left(2\right)}\end{array}\right]---\left(17a\right)$

And

$\left[\begin{array}{c}{r}_1^b\\ r_2^b\end{array}\right]=\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]-\left[\begin{array}{c}{r}_1^{\left(2\right)}\\ r_2^{\left(2\right)}\end{array}\right]---\left(17b\right)$

Warp

${\mathrm{<figure-callout\; id="1"\; label="z"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">z</figure-callout>}}_1=r_1^a+r_2^a---\left(18a\right)$

${\mathrm{<figure-callout\; id="2"\; label="z"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">z</figure-callout>}}_2=r_1^b+r_2^b---\left(18b\right)$

Accomplish combination calculation by signal combiner according to last two formulas, and export combination calculation z as a result ₁And z ₂

Step 5 is used decision device and is carried out decode phase, order

x ₁＝a ₁+jb ₁，a ₁，b ₁∈{0，1}

x ₂＝a ₂+jb ₂，a ₂，b ₂∈{0，1}

Combination calculation is z as a result ₁And z ₂Through the decision device decoding, obtain x ₁And x ₂As follows:

$\mathrm{Re}{\hat{x}}_1=\mathrm{Sign}\left[\mathrm{Re}{z}_1\right]$

$\mathrm{Im}{\hat{x}}_1=\mathrm{Sign}\left[\mathrm{Im}{z}_1\right]$

$\mathrm{Re}{\hat{x}}_2=\mathrm{Sign}\left[\mathrm{Re}{z}_2\right]$

$\mathrm{Im}{\hat{x}}_2=\mathrm{Sign}\left[\mathrm{Im}{z}_2\right]$

Beneficial effect of the present invention

The present invention proposes need not 21 receipts and 22 receipts MIMO space-time coding/decoding systems of channel estimating and channel information; When MIMO receiver according to the present invention is decoded when carrying out sky; Do not need channel information, and then do not need complicated channel estimating subsystem, thereby greatly reduce system complexity and system's realization cost; Because it can effectively improve the utilance and the message transmission rate of wireless frequency spectrum, makes this system in WLAN and wireless MAN, be with a wide range of applications at this.

Description of drawings

Coded system realized block diagram when Fig. 1 was prior art hollow;

Fig. 2 is the Alamouti encoder model of prior art;

Fig. 3 is an Alamouti scheme receiver;

Fig. 4 is 21 of the present invention and receives the mimo system encoder model;

Fig. 5 is the present invention program's a single antenna receiver;

Fig. 6 is the present invention program's a double antenna receiver;

Fig. 7 is the ber curve of the present invention program's single antenna receiver, and wherein, transverse axis is a signal to noise ratio (snr), and the longitudinal axis is the error rate;

Fig. 8 is the ber curve of the present invention program's double antenna receiver, and wherein, transverse axis is a signal to noise ratio (snr), and the longitudinal axis is the error rate.

Embodiment

Below in conjunction with accompanying drawing and embodiment the present invention is described in further detail:

In following two specific embodiments, further specify the beneficial effect of the System and method for of the present invention's proposition through two system emulation experiments.Among two embodiment below, the channel parameter change at random, but receiver is not known channel parameter, not with the channel parameter decoding, and only adopts receiver scheme of the present invention to decode.

Embodiment 1: referring to Fig. 4; Adopt the Space Time Coding device that the present invention program designed among Fig. 4, suppose that usefulness has the planisphere of 4 constellation point to modulate, in encoding operation each time with 2 transmitting antennas; One group of 4 information bit is mapped to signal constellation (in digital modulation), to select 2 modulation signal x ₁And x ₂2 modulation signals are encoded Space-Time Block Coding encoder matrix with the Space Time Coding device according to the present invention

${\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">G</figure-callout>}}_2=\left[\begin{array}{cc}{x}_1& x_1\\ x_2& -{\mathrm{<figure-callout\; id="2"\; label="x"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">x</figure-callout>}}_2\end{array}\right]$

Generate 2 length and be 2 parallel sequence.These sequences were launched through 2 antennas in 2 time cycles: in first cycle, and signal x ₁And x ₂Launch respectively from antenna 1 and 2 simultaneously; In second symbol period, signal x ₁With-x ₂Launch respectively from antenna 1 and 2 simultaneously.In the emulation experiment of present embodiment, every Frame has 1000 symbol x ₁And x ₂, every SNR point is got 10000 Frames.

Receiver adopts Fig. 5 the present invention program's double antenna receiver, and the ber curve of the receiver that obtains is as shown in Figure 7.The present invention program's receiver that goes out as shown in Figure 5 can obtain diversity gain and carry out noise cancellation, order

${\mathrm{<figure-callout\; id="1"\; label="z"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">z</figure-callout>}}_1={\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">r</figure-callout>}}_2=2h_1{x}_1+{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">n</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">n</figure-callout>}}_2=2h_1{x}_1+{\stackrel{\&OverBar;}{n}}_1---\left(19a\right)$

${\mathrm{<figure-callout\; id="2"\; label="z"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">z</figure-callout>}}_2=r_1-{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">r</figure-callout>}}_2=2h_2{x}_2+n_1-{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">n</figure-callout>}}_2=2h_2{x}_2+{\stackrel{\&OverBar;}{n}}_2---\left(19b\right)$

Because interchannel noise is generally white Gaussian noise, two noises are sued for peace or are subtracted each other and mean that noise reduces by half again, ${\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">n</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">n</figure-callout>}}_2={\stackrel{\&OverBar;}{n}}_1\&ap;{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">n</figure-callout>}}_1/2,$ $n_1-{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">n</figure-callout>}}_2={\stackrel{\&OverBar;}{n}}_2\&ap;{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">n</figure-callout>}}_2/2,$ So

z ₁＝2h ₁x ₁+n ₁/2 (20a)

z ₂＝2h ₂x ₂+n ₂/2 (20b)

Can know that by formula (20a) with (20b) single antenna receiver of the present invention has obtained 4h ₁And 4h ₂Diversity gain, this 4h ₁And 4h ₂Diversity gain can reduce the error rate of receiver greatly.

Visible by Fig. 7, although the present invention program's single antenna receiver does not have channel estimating, and do not adopt channel matrix to decode,, still obtained good ber curve, especially, behind SNR＞18dB, the error rate is 0.

Embodiment 2: as shown in Figure 4; Present embodiment adopts the Space Time Coding device with 2 transmitting antennas that the present invention program designed shown in Fig. 4; Suppose with there being the planisphere of 4 constellation point to modulate; In encoding operation each time, one group of 4 information bit is mapped to signal constellation (in digital modulation), to select 2 modulation signal x ₁And x ₂2 modulation signals are encoded Space-Time Block Coding encoder matrix with the Space Time Coding device according to the present invention

${\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">G</figure-callout>}}_2=\left[\begin{array}{cc}{x}_1& x_1\\ x_2& -{\mathrm{<figure-callout\; id="2"\; label="x"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">x</figure-callout>}}_2\end{array}\right],$

Generate 2 length and be 2 parallel sequence.These sequences were launched through 2 antennas in 2 time cycles: in first cycle, and signal x ₁And x ₂Launch respectively from antenna 1 and 2 simultaneously; In second symbol period, signal x ₁With-x ₂Launch respectively from antenna 1 and 2 simultaneously.In the emulation experiment of present embodiment, every Frame has 1000 symbol x ₁And x ₂, every SNR point is got 10000 Frames.

Receiver adopts the present invention program's shown in Figure 6 double antenna receiver, and the ber curve of the receiver that obtains is as shown in Figure 8.Double antenna receiver scheme of the present invention illustrated in fig. 6 can obtain diversity gain and carry out noise cancellation, order

${\mathrm{<figure-callout\; id="1"\; label="z"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">z</figure-callout>}}_1=r_1^a+r_2^a=2(h_{11}+h_{12})x_1+n_1^{\left(1\right)}+n_1^{\left(2\right)}+n_2^{\left(1\right)}+n_2^{\left(2\right)}---\left(21a\right)$

${\mathrm{<figure-callout\; id="2"\; label="z"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">z</figure-callout>}}_2=r_1^a-r_2^a=2(h_{21}+h_{22})x_2+n_1^{\left(1\right)}+n_1^{\left(2\right)}-n_2^{\left(1\right)}-n_2^{\left(2\right)}---\left(22b\right)$

Because interchannel noise is generally white Gaussian noise,

$n_1^{\left(1\right)}+n_1^{\left(2\right)}+n_2^{\left(1\right)}+n_2^{\left(2\right)}\&ap;n_1^{\left(1\right)}/4,$

$n_1^{\left(1\right)}+n_1^{\left(2\right)}-n_2^{\left(1\right)}-n_2^{\left(2\right)}\&ap;n_2^{\left(1\right)}/4$

So

${\mathrm{<figure-callout\; id="1"\; label="z"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">z</figure-callout>}}_1=2(h_{11}+h_{12})x_1+n_1^{\left(1\right)}/4---\left(22a\right)$

${\mathrm{<figure-callout\; id="2"\; label="z"\; filenames="H2009100908576E00022.png"\; state="\{\{state\}\}">z</figure-callout>}}_2=2(h_{21}+h_{22})x_2+n_2^{\left(1\right)}/4---\left(22b\right)$

Can know that by formula (22a) with (22b) double antenna receiver according to the present invention has obtained 8 (h ₁₁+ h ₁₂) and 8 (h ₂₁+ h ₂₂) diversity gain, this 8 (h ₁₁+ h ₁₂) and 8 (h ₂₁+ h ₂₂) diversity gain can reduce the error rate of receiver greatly.

Visible by Fig. 8, although the present invention program's double antenna receiver does not have channel estimating, and do not adopt channel matrix to decode,, still obtain good ber curve, especially, behind SNR＞14dB, the error rate is 0.

Claims (4)

1. one kind need not 21 of channel information and receives MIMO machine space-time coding/decoding systems; It is characterized in that; Comprise: receiver when Space Time Coding device end, single antenna sky, wherein, Space Time Coding device end is made up of information source, modulator, Space Time Coding device, transmitting antenna 1 and transmitting antenna 2; Receiver comprised when single antenna was empty: reception antenna, the last branch road that has access to buffer, the following branch road that has access to electronic switch, signal combiner and a decision device 1, decision device 2; The course of work of each part of said space-time coding/decoding system is following:

Emission process: the Space Time Coding device is at first with having 2 ^bThe planisphere of individual constellation point is modulated 2b information bit, in encoding operation each time, one group of 2b information bit is mapped to signal constellation (in digital modulation), to select 2 modulation signal x ₁And x ₂, with the Space Time Coding device 2 modulation signals are encoded then, after modulators modulate, to send into the Space Time Coding device and carry out encoding process, encoder matrix is:

$G_2=\left[\begin{array}{cc}{x}_1& x_1\\ x_2& -x_2\end{array}\right],$

Generating 2 length by encoder matrix is 2 parallel signal sequences; These bursts are launched through 2 antennas in 2 time slots: at first time slot, and burst x ₁And x ₂Launch respectively from antenna 1 and 2 simultaneously; At second time slot, burst x ₁With-x ₂Launch respectively from antenna 1 and 2 simultaneously;

Receiving course: the reception antenna of single antenna receiver receives transmitting antenna 1 signal to be decoded that 2 emissions come with transmitting antenna, receives signal accordingly and is shown at t and t+T timetable:

r ₁＝r(t)＝h ₁x ₁+h ₂x ₂+n ₁

r ₂＝r(t+T)＝h ₁x ₁-h ₂x ₂+n ₂

N wherein ₁And n ₂Be illustrated respectively in the channel additive Gaussian noise that t and t+T receive constantly, they are independent identically distributed complex random variable, and its average is zero, power spectral density is N ₀/ 2; The reception signal r (t) of receiver was r at the 1st time slot when single antenna was empty ₁, r ₁Through last branch road buffer memory in buffer, this at present the electronic switch of branch road open r ₁Can not pass through branch road down; Receiving signal r (t) is r at the 2nd time slot ₂, the 2nd time slot is the electronic switch closes of branch road at present, r ₂R through following branch road entering signal combiner and buffer memory ₁Carry out combination calculation, order:

z ₁＝r ₁+r ₂

z ₂＝r ₁-r ₂

Accomplish combination calculation by signal combiner according to last two formulas, and export combination calculation z as a result ₁And z ₂Signal combiner result of calculation is sent into decision device 1 respectively carries out signal decoding, order with decision device 2:

x ₁＝a ₁+jb ₁，a ₁，b ₁∈{0，1}，

x ₂＝a ₂+jb ₂，a ₂，b ₂∈{0，1}；

The decision device of receiver was decoded the decoded information bit x after obtaining diversity gain and carrying out noise cancellation when single antenna was empty ₁And x ₂As follows:

$\mathrm{Re}{\hat{x}}_1=\mathrm{Sign}\left[\mathrm{Re}{z}_1\right],$

$\mathrm{Im}{\hat{x}}_1=\mathrm{Sign}\left[\mathrm{Im}{z}_1\right],$

$\mathrm{Re}{\hat{x}}_2=\mathrm{Sign}\left[\mathrm{Re}{z}_2\right],$

$\mathrm{Im}{\hat{x}}_2=\mathrm{Sign}\left[\mathrm{Im}{z}_2\right].$

2. 21 receipts MIMO space-time coding/decoding methods that need not channel information is characterized in that, may further comprise the steps:

Step 1: in the modulating-coding stage, Space Time Coding device end is at first with having 2 ^bThe planisphere of individual constellation point is modulated 2b information bit, in encoding operation each time, one group of 2b information bit is mapped to signal constellation (in digital modulation), to select 2 modulation signal x ₁And x ₂, with the Space Time Coding device 2 modulation signals are encoded then, according to the Space-Time Block Coding encoder matrix:

$G_2=\left[\begin{array}{cc}{x}_1& x_1\\ x_2& -x_2\end{array}\right]$

Generate 2 length and be 2 parallel sequence;

Step 2: launching phase, the parallel sequence behind the modulating-coding in the step was launched through 2 antennas in 2 time cycles: at first time slot, signal x ₁And x ₂Launch respectively from antenna 1 and 2 simultaneously; At second time slot, signal x ₁With-x ₂Launch respectively from antenna 1 and 2 simultaneously;

Step 3: receive signal phase, the reception antenna of receiver was responsible for receiving the signal of transmission antennas transmit when single antenna was empty, received signal accordingly and was shown at t and t+T timetable:

r ₁＝r(t)＝h ₁x ₁+h ₂x ₂+n ₁

r ₂＝r(t+T)＝h ₁x ₁-h ₂x ₂+n ₂

Wherein, n ₁And n ₂Be illustrated respectively in the channel additive Gaussian noise that t and t+T receive constantly, the two is independent identically distributed complex random variable, and its average is zero, power spectral density is N ₀/ 2;

Step 4: the combination calculation stage of receiver when single antenna is empty, one of which, the 1st time slot, receiving signal r (t) is r at the 1st time slot ₁, r ₁Through last branch road buffer memory in buffer, this at present the electronic switch of branch road open r ₁Can not pass through branch road down; Its two, the 2 time slot, receiving signal r (t) is r at the 2nd time slot ₂, the 2nd time slot is the electronic switch closes of branch road at present, r ₂R through following branch road entering signal combiner and buffer memory ₁Carry out combination calculation, order:

z ₁＝r ₁+r ₂

z ₂＝r ₁-r ₂

Accomplish combination calculation by signal combiner according to last two formulas, and export combination calculation z as a result ₁And z ₂

Step 5: the decision device of receiver carried out decode phase when single antenna was empty, order:

x ₁＝a ₁+jb ₁，a ₁，b ₁∈{0，1}，

x ₂=a ₂+ jb ₂, a ₂, b ₂∈ 0, and 1}, combination calculation is z as a result ₁And z ₂Through the decision device decoding, obtain x ₁And x ₂As follows:

$\mathrm{Re}{\hat{x}}_1=\mathrm{Sign}\left[\mathrm{Re}{z}_1\right],$

$\mathrm{Im}{\hat{x}}_1=\mathrm{Sign}\left[\mathrm{Im}{z}_1\right],$

$\mathrm{Re}{\hat{x}}_2=\mathrm{Sign}\left[\mathrm{Re}{z}_2\right],$

$\mathrm{Im}{\hat{x}}_2=\mathrm{Sign}\left[\mathrm{Im}{z}_2\right].$

3. one kind need not 22 of channel information and receives MIMO machine space-time coding/decoding systems; It is characterized in that; Comprise: receiver when encoder-side and double antenna are empty, wherein, encoder-side is made up of information source, modulator, Space Time Coding device, transmitting antenna 1 and transmitting antenna 2; Receiver comprised when double antenna was empty: reception antenna 1, reception antenna 2, the last branch road that has access to buffer, the following branch road that has access to electronic switch, signal combiner and decision device 1, decision device 2; The course of work between this each building block of space-time coding/decoding system is following:

Emission process: the information bit that information source transmits is sent into the Space Time Coding device and is carried out encoding process after modulators modulate, the Space Time Coding device is at first with having 2 ^bThe planisphere of individual constellation point is modulated 2b information bit, in encoding operation each time, one group of 2b information bit is mapped to signal constellation (in digital modulation), to select 2 modulation signal x ₁And x ₂, with the Space Time Coding device 2 modulation signals to be encoded then, encoder matrix is:

$G_2=\left[\begin{array}{cc}{x}_1& x_1\\ x_2& -x_2\end{array}\right],$

Generating 2 length by encoder matrix is 2 parallel signal sequences; These bursts are launched through 2 antennas in 2 time slots: at first time slot, and burst x ₁And x ₂Launch respectively from antenna 1 and 2 simultaneously; At second time slot, burst x ₁With-x ₂Launch respectively from antenna 1 and 2 simultaneously;

Receiving course: the reception antenna of receiver connect 1 and receives transmitting antenna 1 signal to be decoded that 2 emissions come with transmitting antenna respectively with reception antenna 2 when double antenna was empty,

$\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]=\left[\begin{array}{cc}{h}_{11}& h_{12}\\ h_{21}& h_{22}\end{array}\right]\left[\begin{array}{c}{x}_1\\ x_2\end{array}\right]+\left[\begin{array}{c}{n}_1^{\left(1\right)}\\ n_2^{\left(1\right)}\end{array}\right]$

$\left[\begin{array}{c}{r}_1^{\left(2\right)}\\ r_2^{\left(2\right)}\end{array}\right]=\left[\begin{array}{cc}{h}_{11}& -h_{12}\\ h_{21}& -h_{22}\end{array}\right]\left[\begin{array}{c}{x}_1\\ x_2\end{array}\right]+\left[\begin{array}{c}{n}_1^{\left(2\right)}\\ n_2^{\left(2\right)}\end{array}\right]$

Wherein

With

With

Be illustrated respectively in the channel additive Gaussian noise that t and t+T receive constantly, they are independent identically distributed complex random variable, and its average is zero, power spectral density is N ₀/ 2;

Receiving signal r (t) at the 1st time slot does $\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right],$ $\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]$ Through last branch road buffer memory in buffer, this at present the electronic switch of branch road open, $\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]$ Can not pass through branch road down; Receiving signal r (t) at the 2nd time slot does $\left[\begin{array}{c}{r}_1^{\left(2\right)}\\ r_2^{\left(2\right)}\end{array}\right],$ The 2nd time slot is the electronic switch closes of branch road at present, $\left[\begin{array}{c}{r}_1^{\left(2\right)}\\ r_2^{\left(2\right)}\end{array}\right]$ Through down branch road entering signal combiner and buffer memory $\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]$ Carry out combination calculation, order:

$\left[\begin{array}{c}{r}_1^a\\ r_2^a\end{array}\right]=\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]+\left[\begin{array}{c}{r}_1^{\left(2\right)}\\ r_2^{\left(2\right)}\end{array}\right]$

And

$\left[\begin{array}{c}{r}_1^b\\ r_2^b\end{array}\right]=\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]-\left[\begin{array}{c}{r}_1^{\left(2\right)}\\ r_2^{\left(2\right)}\end{array}\right]$

Warp

$z_1=r_1^a+r_2^a$

$z_2=r_1^b+r_2^b$

Accomplish combination calculation by signal combiner according to last two formulas, and export combination calculation z as a result ₁And z ₂Signal combiner result of calculation is sent into decision device 1 and decision device 2 respectively, and combination calculation is z as a result ₁And z ₂Through the decision device decoding, order:

x ₁＝a ₁+jb ₁，a ₁，b ₁∈{0，1}

x ₂＝a ₂+jb ₂，a ₂，b ₂∈{0，1}

After decision device 1 and decision device are decoded, the decoded information bit x after obtaining diversity gain and carrying out noise cancellation ₁And x ₂As follows:

$\mathrm{Re}{\hat{x}}_1=\mathrm{Sign}\left[\mathrm{Re}{z}_1\right]$

$\mathrm{Im}{\hat{x}}_1=\mathrm{Sign}\left[\mathrm{Im}{z}_1\right]$

$\mathrm{Re}{\hat{x}}_2=\mathrm{Sign}\left[\mathrm{Re}{z}_2\right]$

$\mathrm{Im}{\hat{x}}_2=\mathrm{Sign}\left[\mathrm{Im}{z}_2\right].$

4. 22 receipts MIMO machine space-time coding methods that need not channel information is characterized in that, comprising:

Step 1: the modulating-coding stage, at first with having 2 ^bThe planisphere of individual constellation point is modulated 2b information bit, in encoding operation each time, one group of 2b information bit is mapped to signal constellation (in digital modulation), to select 2 modulation signal x ₁And x ₂, with the Space Time Coding device 2 modulation signals are encoded then, according to the Space-Time Block Coding encoder matrix:

$G_2=\left[\begin{array}{cc}{x}_1& x_1\\ x_2& -x_2\end{array}\right]$

Generate 2 length and be 2 parallel sequence;

Step 2: launching phase, the parallel sequence behind the modulating-coding in the step 1 was launched through 2 antennas in 2 time cycles: at the 1st time slot, signal x ₁And x ₂Launch respectively from antenna 1 and 2 simultaneously; At the 2nd time slot, signal x ₁With-x ₂Launch respectively from antenna 1 and 2 simultaneously;

Step 3: in the reception stage, the reception antenna of receiver was responsible for receiving the signal of transmission antennas transmit when double antenna was empty, received signal accordingly and was shown at t and t+T timetable:

$\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]=\left[\begin{array}{cc}{h}_{11}& h_{12}\\ h_{21}& h_{22}\end{array}\right]\left[\begin{array}{c}{x}_1\\ x_2\end{array}\right]+\left[\begin{array}{c}{n}_1^{\left(1\right)}\\ n_2^{\left(1\right)}\end{array}\right]$

$\left[\begin{array}{c}{r}_1^{\left(2\right)}\\ r_2^{\left(2\right)}\end{array}\right]=\left[\begin{array}{cc}{h}_{11}& -h_{12}\\ h_{21}& -h_{22}\end{array}\right]\left[\begin{array}{c}{x}_1\\ x_2\end{array}\right]+\left[\begin{array}{c}{n}_1^{\left(2\right)}\\ n_2^{\left(2\right)}\end{array}\right]$

Wherein

With

With Be illustrated respectively in the channel additive Gaussian noise that t and t+T receive constantly, they are independent identically distributed complex random variable, and its average is zero, power spectral density is N ₀/ 2;

The combination calculation stage of receiver when step 4 double antenna is empty, one of which, the 1st time slot, reception signal r (t) at the 1st time slot does $\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right],$ $\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]$ Through last branch road buffer memory in buffer, this at present the electronic switch of branch road open, $\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]$ Can not pass through branch road down; Its two, the 2 time slot, reception signal r (t) at the 2nd time slot does $\left[\begin{array}{c}{r}_1^{\left(2\right)}\\ r_2^{\left(2\right)}\end{array}\right],$ The 2nd time slot is the electronic switch closes of branch road at present, $\left[\begin{array}{c}{r}_1^{\left(2\right)}\\ r_2^{\left(2\right)}\end{array}\right]$ Through down branch road entering signal combiner and buffer memory $\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]$ Carry out combination calculation, order:

$\left[\begin{array}{c}{r}_1^a\\ r_2^a\end{array}\right]=\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]+\left[\begin{array}{c}{r}_1^{\left(2\right)}\\ r_2^{\left(2\right)}\end{array}\right]$

And

$\left[\begin{array}{c}{r}_1^b\\ r_2^b\end{array}\right]=\left[\begin{array}{c}{r}_1^{\left(1\right)}\\ r_2^{\left(1\right)}\end{array}\right]-\left[\begin{array}{c}{r}_1^{\left(2\right)}\\ r_2^{\left(2\right)}\end{array}\right]$

Warp

$z_1=r_1^a+r_2^a$

$z_2=r_1^b+r_2^b$

Accomplish combination calculation by signal combiner according to last two formulas, and export combination calculation z as a result ₁And z ₂

The decision device of receiver carried out decode phase when step 5 double antenna was empty, order:

x ₁＝a ₁+jb ₁，a ₁，b ₁∈{0，1}

x ₂＝a ₂+jb ₂，a ₂，b ₂∈{0，1}

Combination calculation is z as a result ₁And z ₂Through the decision device decoding, obtain x ₁And x ₂As follows:

$\mathrm{Re}{\hat{x}}_1=\mathrm{Sign}\left[\mathrm{Re}{z}_1\right]$

$\mathrm{Im}{\hat{x}}_1=\mathrm{Sign}\left[\mathrm{Im}{z}_1\right]$

$\mathrm{Re}{\hat{x}}_2=\mathrm{Sign}\left[\mathrm{Re}{z}_2\right]$

$\mathrm{Im}{\hat{x}}_2=\mathrm{Sign}\left[\mathrm{Im}{z}_2\right].$

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