CN102098142A - Data transmission method, device and system - Google Patents

Abstract

The embodiment of the invention provides a data transmission method, device and system. The method comprises the following steps of: receiving source signals transmitted by at least two source nodes to obtain received signals; decoding the received signals to obtain estimation signals of the source signals; performing network pre-coding on the estimation signals, and transmitting the pre-coded signals to destination nodes. In the embodiment of the invention, relay nodes perform network pre-coding on the signals transmitted by the source nodes, so that the data transmission of a multi-user multi-input multi-output (MIMO) relay channel in a wireless communication network has high throughput, and the transmission efficiency is effectively increased.

Description

Data transmission method, device and system

Technical field

The present invention relates to wireless technical field, relate in particular to multiple-input and multiple-output (Multiple-Input Multiple Output, MIMO) data transmission method of trunk channel, device and the system of a kind of multi-user in the wireless relay network.

Background technology

At present, moving communicating field extensively adopts relaying to help the mobile subscriber and transmits data, and this communication mode has utilized the collaboration feature of relaying, makes to obtain extra collaboration diversity gain in the transfer of data, thereby improve the error rate (Bit Error Rate, the BER) performance of receiving terminal.In addition, along with the proposition of MIMO technology, can improve the quality that relaying is transmitted data more effectively.

In large-scale wireless relay communication network, normally multiple source node and a plurality of via node coexistence, in traditional trunking plan, each relaying need be transmitted data one by one for each source node, makes efficiency of transmission decline to a great extent along with the increase of network size.Come the data of the multiple source node that receives are carried out encoding process by network code at the relaying place, send data behind the coding again, decode the data that need by destination node at last to destination node.The transmission means of this network code can improve the number of transmissions of network throughput, minimizing packet, the fault-tolerance and the robustness of enhancing wireless network.

The relay transmission scheme of existing coding Network Based roughly can be divided into two kinds: the relay transmission scheme of finite field network code and the relay transmission scheme of complex field network code, wherein the network throughput of the relay transmission scheme of finite field network code is 1/ (N _S+ 1) symbol/information source/time slot, N _SBe the number of source node in the network, as seen, along with the increase of network size, the network throughput of this scheme descends too much; Network throughput stuck-at-/2 symbols/information source/the time slot of the relay transmission scheme of complex field network code, it is not subjected to the restriction of information source number, but this throughput is not very good.

Summary of the invention

The invention provides a kind of data transmission method, device and system, for multiuser MIMO trunk channel in the cordless communication network provides a kind of transmission plan with high-throughput.

The embodiment of the invention provides a kind of data transmission method, and this method comprises: receive the source signal that at least two source nodes send, obtain received signal; Described received signal is decoded, obtain the estimated signal of described source signal; Described estimated signal is carried out the network precoding, and precoded signal is sent to destination node.

The embodiment of the invention also provides a kind of data transmission method, and this method comprises: receive the source signal that at least two source nodes send, obtain received signal; Receive the precoded signal that via node sends, described precoded signal is decoded to the received signal that the source signal that sends according to described at least two source nodes obtains by described via node, obtain estimated signal, and estimated signal is carried out the network precoding obtain; Decode according to described received signal and described precoded signal.

The embodiment of the invention provides a kind of relaying, comprising: the source signal receiving element, be used to receive the source signal that at least two source nodes send, and obtain received signal; Decoding unit is used for described received signal is decoded, and obtains the estimated signal of described source signal; The network precoding unit is used for described estimated signal is carried out the network precoding; Transmitting element is used for and will be sent to destination node through the signal after the precoding of described network precoding unit.

The embodiment of the invention also provides a kind of device, comprising: the source signal receiving element, be used to receive the source signal that at least two source nodes send, and obtain received signal; The code signal receiving element, be used to receive the precoded signal that via node sends, described precoded signal is decoded to the received signal that the source signal that sends according to described at least two source nodes obtains by described via node, obtain estimated signal, and estimated signal is carried out the network precoding obtain; Decoding unit is used for decoding according to described received signal and described precoded signal.

The embodiment of the invention also provides a kind of data transmission system, comprises above-mentioned relaying, said apparatus and at least two source nodes, and described source node transmits data by above-mentioned relaying to said apparatus.

The embodiment of the invention is carried out the network precoding by via node to the signal that source node sent, thereby make that the transfer of data of multiuser MIMO trunk channel has higher throughput in the cordless communication network, efficiency of transmission has obtained effective raising, has further improved the bit error rate performance of system simultaneously.

Description of drawings

In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, to do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below, apparently, accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.

A kind of wireless relay network structure chart that Fig. 1 uses for the embodiment of the invention;

A kind of data transmission method flow chart that Fig. 2 provides for the embodiment of the invention;

The another kind of data transmission method flow chart that Fig. 3 provides for the embodiment of the invention;

The another kind of data transmission method flow chart that Fig. 4 provides for the embodiment of the invention;

The another kind of data transmission method flow chart that Fig. 5 provides for the embodiment of the invention;

The structural representation of a kind of relaying that Fig. 6 provides for the embodiment of the invention;

The structural representation of a kind of network code unit that Fig. 7 provides for the embodiment of the invention;

The structural representation of a kind of device that Fig. 8 provides for the embodiment of the invention;

The structural representation of the another kind of device that Fig. 9 provides for the embodiment of the invention;

A kind of system construction drawing that Figure 10 provides for the embodiment of the invention;

Figure 11 is that the network pre-coding scheme of the embodiment of the invention and the performance of complex field network code compare emulated data figure;

Figure 12 is that the performance of network pre-coding scheme under different throughput situations of the embodiment of the invention compares emulated data figure.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that is obtained under the creative work prerequisite.

At first the applied environment of the embodiment of the invention is described, be illustrated in figure 1 as a kind of wireless relay network structure chart that the embodiment of the invention is used.By among the figure as can be known, this wireless relay network comprises source node S ₁-S _Ns, via node R and destination node D, wherein via node R and destination node D are multi-antenna structure.Solid line represents that source node broadcasts to via node and destination node among the figure, and dotted line represents that via node sends data to destination node.Certainly, in actual conditions, can comprise a plurality of via nodes in this wireless relay network, but for each via node, their performed operations all are similar, therefore illustrate the situation of a via node at this.

Be illustrated in figure 2 as a kind of data transmission method flow chart that the embodiment of the invention provides, present embodiment is that the angle from via node describes, and this method comprises the steps:

S201: receive the source signal that at least two source nodes send, obtain received signal.Because the broadcast characteristic of wireless signal, every antenna on the via node all can be received the signal that all source nodes send, and promptly receives N _SIndividual signal supposes that the via node among Fig. 1 has N root antenna, and then via node can be received following signal at time slot t:

y _SR(t)＝H _SRx(t)+n _SR(t)；

Wherein, $x\left(t\right)={({\mathrm{\θ}}_1{x}_1\left(t\right),...,{\mathrm{\θ}}_{N_S}{x}_{\mathrm{Ns}}\left(t\right))}^T$ Expression N _SThe signal that individual source node sends in t time slot; n _SR(t) white Gaussian noise between expression source node and the via node R; H _SRExpression N _SChannel fading matrix between individual source node and the via node R, and

$H_{\mathrm{SR}}=\left(\begin{array}{ccc}{h}_{S_{1}R}^1& ...& h_{S_{N_S}R}^1\\ .& .& .\\ .& .& .\\ .& .& .\\ h_{S_{1}R}^N& ...& h_{S_{N_S}R}^N\end{array}\right)$

Wherein

The expression source node i arrives the channel fading coefficient between the j root antenna of via node, j=1 ..., N.

S202: this received signal is decoded, obtain the estimated signal of above-mentioned source signal.

Can calculate the estimated signal of above-mentioned source signal according to following formula

$\hat{x}\left(t\right)=\underset{x\left(t\right)}{\arg \min }{\left|\right|y_{\mathrm{SR}}\left(t\right)-H_{\mathrm{SR}}x\left(t\right)\left|\right|}^2;$

Obtain having N _SThe estimated signal vector of individual element: $\hat{x}\left(t\right)={\left(\begin{array}{ccc}{\hat{x}}_1\left(t\right)& ...& {\hat{x}}_{N_S}\left(t\right)\end{array}\right)}^T.$

S203: this estimated signal is carried out the network precoding, and precoded signal is sent to destination node.

So-called network precoding is meant the co-design of via node network code and precoding technique, by determining of network code vector sum precoding vector, at first estimated signal is carried out the complex field network code, and then the pooling information that obtains carried out precoding processing, compare the great systematic function that improved with existing junction network coding techniques.

In embodiments of the present invention, via node R basis is at T _SEstimated signal in the individual time slot

The tectonic network pre-coding scheme, these estimated signal can constitute the estimated signal vector $\hat{x}={(\hat{x}\left(t\right),\hat{x}(t+1),...,\hat{x}(t+T_S-1))}^T,$ For this estimated signal vector is carried out the network precoding, need obtain m precoding vector P _mWith network code vector θ _Rm, wherein m is the number of the sub-information flow of participation network precoding.Obtain tieing up sub-information flow according to following formula then through m N behind the network code:

$x_R=(P_1{\mathrm{\θ}}_{R1}\hat{x},P_2{\mathrm{\θ}}_{R2}\hat{x}...,P_m{\mathrm{\θ}}_{\mathrm{Rm}}\hat{x});$

Last via node R is with above-mentioned x _RGive destination node D by N root antenna transmission, destination node D decodes to obtain required information to it.Destination node D can be by following manner to x _RDecode:

At first, because the broadcast characteristic of wireless signal, destination node D is the same with via node R, also can receive source node S ₁-S _NsThe signal that is sent also has N root antenna at this hypothesis goal node, and its source node signal of receiving is designated as y _SD(t), then:

y _SD(t)＝H _SDx(t)+n _SD(t)；

Wherein, $x\left(t\right)={({\mathrm{\θ}}_1{x}_1\left(t\right),...,{\mathrm{\θ}}_{N_S}{x}_{\mathrm{Ns}}\left(t\right))}^T$ Expression N _SThe signal that individual source node sends in t time slot; n _SD(t) white Gaussian noise between expression source node and the destination node D; H _SDExpression N _SChannel fading matrix between individual source node and the destination node D:

$H_{\mathrm{SD}}=\left(\begin{array}{ccc}{h}_{S_{1}D}^1& ...& h_{S_{N_S}D}^1\\ .& & .\\ .& ...& .\\ .& & .\\ h_{S_{1}D}^N& ...& h_{S_{N_S}D}^N\end{array}\right)$

Wherein

Represent source node i to the channel fading coefficient between the j root antenna of destination node D, j=1 ..., N;

Then, destination node D is according to the source node signal y that receives _SD(t) and via node R transmitted through the signal x behind the network code _R, utilize maximum likelihood decoding to obtain needed signal.So-called maximum likelihood decoding is that demodulator gives decoder a likelihood information sequence or a non-quantized output about " different modulating device incoming symbol possibility ", allow decoder that these information and coded message are combined and make judgement, systematic function can be greatly improved like this, therefore can calculate the likelihood information and the addition of source node and via node earlier, and then translate code word by decoder.

The embodiment of the invention is carried out the network precoding by via node to the signal that source node sent, thereby make that the transfer of data of multiuser MIMO trunk channel has higher throughput in the cordless communication network, efficiency of transmission has obtained effective raising, has further improved the bit error rate performance of system simultaneously.

Present embodiment is to the further describing of the foregoing description, and is illustrated in figure 3 as the another kind of data transmission method flow chart that the embodiment of the invention provides, and this method comprises the steps:

S301: utilize many antennas to receive the source signal that at least two source nodes send, obtain received signal.

S302: this received signal is decoded to obtain the estimated signal of above-mentioned source signal.

Step 201 and 202 similar is just no longer given unnecessary details at this in the method that step S301 in the embodiment of the invention and step S302 and the described embodiment of Fig. 2 provide.

S303: the precoding vector and the network code vector that receive the destination node feedback by unlimited feedback channel and/or Limited Feedback channel.

In the present embodiment, precoding vector P _mWith network code vector θ _RmObtain by destination node D, and then feed back to via node R by two kinds of feedback channels.So-called unlimited feedback channel is meant that the number of bits of feedback of feedback channel between destination node and the via node is an endless, and so-called Limited Feedback channel is meant that the feedback channel between destination node and the via node can only feed back the information of limit bit.It is pointed out that and work as feedback channel not simultaneously, precoding vector P _mWith network code vector θ _RmObtain also differently, be described respectively below:

When the feedback channel between relaying node R and destination node D is unlimited feedback channel, precoding vector P _mWith network code vector θ _RmObtain and can comprise the steps:

Channel fading matrix H between step 1, destination node D pair and the via node R _RDCarry out singular value decomposition and calculate the signal to noise ratio λ of each parallel sub-channels _iE _S/ N ₀, H wherein _RDCan represent by following formula:

$H_{\mathrm{RD}}=\left(\begin{array}{c}{h}_{\mathrm{RD}}^1\\ .\\ .\\ .\\ h_{\mathrm{RD}}^N\end{array}\right)$

Step 2, destination node D are compared the signal to noise ratio and the default thresholding signal to noise ratio of each parallel sub-channels of calculating in the step 1, select m the pairing characteristic vector of signal to noise ratio greater than the thresholding signal to noise ratio as precoding vector P _m

Step 3, destination node D choose inverse FFT IFFT matrix, and the principle that reaches according to the channel capacity maximum according to above-mentioned precoding vector obtains network code vector θ from this IFFT matrix _Rm

The forward signal that destination node D receives from the relaying node R is:

$y_{\mathrm{RD}}=H_{\mathrm{RD}}{x}_R+n_{\mathrm{RD}}=H_{\mathrm{RD}}(P_1{\mathrm{\θ}}_{R1}\hat{x},P_2{\mathrm{\θ}}_{R2}\hat{x}...,P_m{\mathrm{\θ}}_{\mathrm{Rm}}\hat{x})+n_{\mathrm{RD}};$

Wherein, x _RBe the signal after the precoding of via node process network, and n _RDBe the white Gaussian noise of via node to destination node, therefore, the m that from the IFFT matrix, chooses network code vector θ _RmNeed satisfy following formula:

$({\mathrm{\&theta;}}_{R1},{\mathrm{\&theta;}}_{R2},...,{\mathrm{\&theta;}}_{\mathrm{Rm}})=\arg \underset{{\mathrm{\&theta;}}_i\&Element;\{{\mathrm{\&theta;}}_i,i=\mathrm{1,2},...,M\}}{\max }\frac{1}{m}\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}{\log }_2\det (I_M+\frac{E_s}{{\mathrm{<figure-callout\; id="0"\; label="NN"\; filenames="H2009102592648E00061.png"\; state="\{\{state\}\}">NN</figure-callout>}}_0}{\mathrm{\&theta;}}_i^{*}{P}_i^{*}{H}_{\mathrm{RD}}^{*}{H}_{\mathrm{RD}}{P}_i{\mathrm{\&theta;}}_i).$

Choosing of above-mentioned IFFT matrix according to L=N _sT _sCarry out, wherein N _sBe the number of described source node, T _sBe number of time slots, it can be divided into following three kinds of situations:

(1) if L=2 ^k, k is a positive integer, then this IFFT matrix is:

$F_1=\left(\begin{array}{ccccc}1& 1& 1& ...& 1\\ 1& \exp \left(\frac{\mathrm{\&pi;}((4-1)\&times;1)}{2L}i\right)& \exp \left(\frac{\mathrm{\&pi;}((4-1)\&times;2)}{2L}i\right)& ...& \exp \left(\frac{\mathrm{\&pi;}\left((4-1)(L-1)\right)}{2L}i\right)\\ 1& \exp \left(\frac{\mathrm{\&pi;}((4\&times;2-1)\&times;1)}{2L}i\right)& \exp \left(\frac{\mathrm{\&pi;}((4\&times;2-1)\&times;2)}{2L}i\right)& ...& \exp \left(\frac{\mathrm{\&pi;}((4\&times;2-1)\&times;(L-1))}{2L}i\right)\\ .& .& .& .& .\\ .& .& .& .& .\\ .& .& .& .& .\\ 1& \exp \left(\frac{\mathrm{\&pi;}((4\&times;(L-1)-1)\&times;1)}{2L}i\right)& \exp \left(\frac{\mathrm{\&pi;}((4\&times;(L-1)-1)\&times;2)}{2L}i\right)& ...& \exp \left(\frac{\mathrm{\&pi;}((4\&times;(L-1)-1)\&times;(L-1))}{2L}i\right)\end{array}\right)$

(2) if L=3 * 2 ^k, k is a positive integer, then this IFFT matrix is:

$F_2=\left(\begin{array}{ccccc}1& 1& 1& ...& 1\\ 1& \exp \left(\frac{\mathrm{\&pi;}((6-1)\&times;1)}{3L}i\right)& \exp \left(\frac{\mathrm{\&pi;}((6-1)\&times;2)}{3L}i\right)& ...& \exp \left(\frac{\mathrm{\&pi;}\left((6-1)(L-1)\right)}{3L}i\right)\\ 1& \exp \left(\frac{\mathrm{\&pi;}(6\&times;2-1)\&times;1)}{2L}i\right)& \exp \left(\frac{\mathrm{\&pi;}((6\&times;2-1)\&times;2)}{3L}i\right)& ...& \exp \left(\frac{\mathrm{\&pi;}((6\&times;2-1)\&times;(L-1))}{3L}i\right)\\ .& .& .& .& .\\ .& .& .& .& .\\ .& .& .& .& .\\ 1& \exp \left(\frac{\mathrm{\&pi;}((6\&times;(L-1)-1)\&times;1)}{3L}i\right)& \exp \left(\frac{\mathrm{\&pi;}((6\&times;(L-1)-1)\&times;2)}{3L}i\right)& ...& \exp \left(\frac{\mathrm{\&pi;}((6\&times;(L-1)-1)\&times;(L-1))}{3L}i\right)\end{array}\right)$

(3) if L does not satisfy for L=2 ^kAnd L=3 * 2 ^kWhen not satisfying, then this IFFT matrix is:

$F_3=\left(\begin{array}{ccccc}1& 1& 1& ...& 1\\ 1& \exp \left(\frac{2\mathrm{\&pi;}(1\&times;1)}{2L}i\right)& \exp \left(\frac{2\mathrm{\&pi;}(1\&times;2)}{2L}i\right)& ...& \exp \left(\frac{2\mathrm{\&pi;}(1\&times;(L-1))}{2L}i\right)\\ 1& \exp \left(\frac{2\mathrm{\&pi;}(2\&times;1)}{2L}i\right)& \exp \left(\frac{2\mathrm{\&pi;}(2\&times;2)}{2L}i\right)& ...& \exp \left(\frac{2\mathrm{\&pi;}(2\&times;(L-1))}{2L}i\right)\\ .& .& .& .& .\\ .& .& .& .& .\\ .& .& .& .& .\\ 1& \exp \left(\frac{2\mathrm{\&pi;}((L-1)\&times;1)}{2L}i\right)& \exp \left(\frac{2\mathrm{\&pi;}(L-1)\&times;2)}{2L}i\right)& ...& \exp \left(\frac{2\mathrm{\&pi;}(L-1)\&times;(L-1))}{2L}i\right)\end{array}\right)$

I in the above-mentioned IFFT matrix ²=-1.

Step 4, destination node D are with above-mentioned network code vector θ _RmSequence number and precoding vector P _mFeed back to via node R by unlimited feedback channel;

Step 5, via node R are according to above-mentioned network code vector θ _RmSequence number from default network code vector θ _RmObtain network code vector θ in the set _Rm

When the feedback channel between relaying node R and destination node D is the Limited Feedback channel, network code vector θ _RmObtain with above-mentioned identical precoding vector P just _mObtain different:

In the present embodiment, have default precoding vector set in the destination node D, so destination node D can choose precoding vector according to the principle of minimal error bit probabilities from this precoding vector set.The principle of so-called minimal error bit probabilities promptly selects to make it to reach minimum precoding vector by calculating BER, is expressed as $T_{\mathrm{opt}}=\arg \underset{T\&Element;\mathrm{\&tau;}}{\min }\stackrel{\&OverBar;}{\mathrm{BER}}(H,T),$ Wherein (H T) is defined as when channel and should be H mutually BER, the average BER when precoding vector is T on k data flow;

Because when feedback channel is the Limited Feedback channel, among the via node R except being preset with the vectorial θ of network code _RmOutside the set, also be preset with precoding vector P _mSet, so destination node D can be with precoding vector P _mSequence number give via node R by the Limited Feedback channel feedback, and by via node R according to this precoding vector P _mSequence number from default precoding vector P _mObtain precoding vector P in the set _m

It is pointed out that precoding vector P in the embodiment of the invention _mWith network code vector θ _RmObtain all and obtain by destination node D, but the embodiment of the invention is not got rid of via node R yet and is finished above-mentioned precoding vector P _mWith network code vector θ _RmObtain.

S304: according to described precoding vector and network code vector estimated signal is carried out the network precoding, promptly obtain tieing up sub-information flow through m N after the network precoding: $x_R=(P_1{\mathrm{\&theta;}}_{R1}\hat{x},P_2{\mathrm{\&theta;}}_{R2}\hat{x}...,P_m{\mathrm{\&theta;}}_{\mathrm{Rm}}\hat{x}).$

S305: with precoded signal by many antenna transmission to destination node so that the signal of this destination node after to above-mentioned coding decoded, this decode procedure is also no longer given unnecessary details at this with the method that the described embodiment of Fig. 2 provides.

The embodiment of the invention is carried out the network precoding by via node to the signal that source node sent, thereby makes that the transfer of data of multiuser MIMO trunk channel has higher throughput in the cordless communication network, and efficiency of transmission has obtained effective raising.The embodiment of the invention adopts different feedback schemes at different feedback channels in addition, makes code efficiency that further raising arranged.

Be illustrated in figure 4 as the another kind of data transmission method flow chart that the embodiment of the invention provides, present embodiment be angle from destination node the present invention will be described, this method comprises the steps:

S401: receive the source signal that at least two source nodes send, obtain received signal.

Because the broadcast characteristic of wireless signal, every antenna on the destination node all can be received the signal that all source nodes send, and promptly receives N _SIndividual signal supposes that the destination node D among Fig. 1 has N root antenna, and then destination node D can receive following signal at time slot t:

y _SD(t)＝H _SDx(t)+n _SD(t)；

Wherein, $x\left(t\right)={({\mathrm{\&theta;}}_1{x}_1\left(t\right),...,{\mathrm{\&theta;}}_{N_S}{x}_{\mathrm{Ns}}\left(t\right))}^T$ Expression N _SThe signal that individual source node sends in t time slot; n _SD(t) expression N _SWhite Gaussian noise between individual source node and the destination node D; H _SDExpression N _SChannel fading matrix between individual source node and the destination node D, and

$H_{\mathrm{SD}}=\left(\begin{array}{ccc}{h}_{S_{1}D}^1& ...& h_{S_{N_S}D}^1\\ .& & .\\ .& ...& .\\ .& & .\\ h_{S_{1}D}^N& ...& h_{S_{N_S}D}^N\end{array}\right);$

Wherein

Represent source node i to the channel fading coefficient between the destination node j root antenna, j=1 ..., N.

S402: the precoded signal after the process network precoding that the reception via node sends.

Via node R carries out the network precoding to the signal that its source node that receives sends, and will send to destination node through the code signal after the network precoding, and the process of network precoding is as follows:

The source node signal that via node R receives is: y _SR(t)=H _SRX (t)+n _SR(t), wherein the lexical or textual analysis of each several part is introduced in embodiment one step S201, and via node R carries out demodulation to obtain the estimated signal of above-mentioned source signal to this received signal then

$\hat{x}\left(t\right)=\underset{x\left(t\right)}{\arg \min }{\left|\right|y_{\mathrm{SR}}\left(t\right)-H_{\mathrm{SR}}x\left(t\right)\left|\right|}^2,$ And then can obtain one and have N _SThe estimated signal vector of individual element: $\hat{x}\left(t\right)={\left(\begin{array}{ccc}{\hat{x}}_1\left(t\right)& ...& {\hat{x}}_{N_S}\left(t\right)\end{array}\right)}^T;$ At last, via node R is with T _SEstimated signal in the individual time slot constitutes the estimated signal vector $\hat{x}={(\hat{x}\left(t\right),\hat{x}(t+1),...,\hat{x}(t+T_S-1))}^T,$ And according to m precoding vector P _mWith network code vector θ _RmAbove-mentioned estimate vector is carried out the network precoding, obtains m N and tie up sub-information flow: $x_R=(P_1{\mathrm{\&theta;}}_{R1}\hat{x},P_2{\mathrm{\&theta;}}_{R2}\hat{x}...,P_m{\mathrm{\&theta;}}_{\mathrm{Rm}}\hat{x}),$ This x _RBe the precoded signal after the network precoding.

S403: decode according to above-mentioned received signal that receives and above-mentioned precoded signal.In the present embodiment, can destination node can decode to above-mentioned code signal according to maximum likelihood decoding.

The embodiment of the invention is carried out the network precoding by via node to the signal that source node sent, thereby makes that the transfer of data of multiuser MIMO trunk channel has higher throughput in the cordless communication network, and efficiency of transmission has obtained effective raising.

Present embodiment is to the further describing of the corresponding embodiment of Fig. 4, and is illustrated in figure 5 as the another kind of data transmission method flow chart that the embodiment of the invention provides, and this method comprises the steps:

S501: utilize many antennas to receive the source signal that at least two source nodes send, obtain received signal.

S502: to and described via node between the channel fading matrix carry out the signal to noise ratio that singular value decomposition is calculated each parallel sub-channels.

S503: will be greater than the pairing characteristic vector of signal to noise ratio of presetting thresholding as precoding vector.

S504: choose inverse FFT IFFT matrix, and the principle that reaches according to the channel capacity maximum according to described precoding vector obtains the network code vector from described IFFT matrix.

Here identical among the selection of IFFT matrix and the embodiment two, just repeated no more at this.The network code vector θ that obtains in this step _RmNeed satisfy following formula:

$({\mathrm{\&theta;}}_{R1},{\mathrm{\&theta;}}_{R2},...,{\mathrm{\&theta;}}_{\mathrm{Rm}})=\arg \underset{{\mathrm{\&theta;}}_i\&Element;\{{\mathrm{\&theta;}}_i,i=\mathrm{1,2},...,M\}}{\max }\frac{1}{m}\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}{\log }_2\det (I_M+\frac{E_s}{{\mathrm{<figure-callout\; id="0"\; label="NN"\; filenames="H2009102592648E00061.png"\; state="\{\{state\}\}">NN</figure-callout>}}_0}{\mathrm{\&theta;}}_i^{*}{P}_i^{*}{H}_{\mathrm{RD}}^{*}{H}_{\mathrm{RD}}{P}_i{\mathrm{\&theta;}}_i).$

S505: the sequence number and the described precoding vector of described network code vector are fed back to described via node by unlimited feedback channel, and via node can obtain the network code vector according to the sequence number of this network code vector from default network code vector set.

S506: the precoded signal after the process network precoding that the reception via node sends.

Via node is according to the precoding vector P that obtains _mWith network code vector θ _RmCarry out the network precoding, obtain m N and tie up sub-information flow: $x_R=(P_1{\mathrm{\&theta;}}_{R1}\hat{x},P_2{\mathrm{\&theta;}}_{R2}\hat{x}...,P_m{\mathrm{\&theta;}}_{\mathrm{Rm}}\hat{x}).$

S507: the precoded signal that received signal that receives according to step S501 and step S506 receive carries out maximum likelihood decoding to obtain desired signal.

It is to be noted, the such scheme destination node is carried out the vector feedback by unlimited feedback channel to via node, but if destination node is to carry out vector feedback time by the Limited Feedback channel to via node, above-mentioned steps S502-S505 can be replaced by following step:

Principle according to the minimal error bit probabilities is chosen precoding vector from the precoding vector set;

Choose suitable IFFT matrix, and from described IFFT matrix, obtain the network code vector according to described precoding vector and according to the principle of channel capacity maximum;

Give described via node with the sequence number of described precoding vector and the sequence number of described network code vector by the Limited Feedback channel feedback, via node obtains the network code vector according to the sequence number of this network code vector from default network code vector set, and obtains precoding vector according to the sequence number of precoding vector from default precoding vector set.

The embodiment of the invention is carried out the network precoding by via node to the signal that source node sent, thereby makes that the transfer of data of multiuser MIMO trunk channel has higher throughput in the cordless communication network, and efficiency of transmission has obtained effective raising.The embodiment of the invention adopts different feedback schemes at different feedback channels in addition, makes code efficiency that further raising arranged.

Be illustrated in figure 6 as the structural representation of a kind of relaying that the embodiment of the invention provides, this relaying comprises: source signal receiving element 610, demodulating unit 620, network precoding unit 630 and transmitting element 640, wherein, demodulating unit 620 links to each other with source signal receiving element 610 and network precoding unit 630 respectively, and transmitting element 640 then links to each other with network precoding unit 630.

Source signal receiving element 610 is used to receive the source signal that at least two source nodes send, and obtains received signal.

Because the broadcast characteristic of wireless signal, every antenna on the via node all can be received the signal that all source nodes send, and promptly receives N _SIndividual signal supposes that the via node among Fig. 1 has N root antenna, and then via node can be received following signal at time slot t:

y _SR(t)＝H _SRx(t)+n _SR(t)；

Wherein, $x\left(t\right)={({\mathrm{\&theta;}}_1{x}_1\left(t\right),...,{\mathrm{\&theta;}}_{N_s}{x}_{\mathrm{Ns}}\left(t\right))}^T$ Expression N _SThe signal that individual source node sends in t time slot; n _SR(t) white Gaussian noise between expression source node and the via node R; H _SRExpression N _SChannel fading matrix between individual source node and the via node R, and

$H_{\mathrm{SR}}=\left(\begin{array}{ccc}{h}_{S_{1}R}^1& ...& h_{S_{N_S}R}^1\\ .& & .\\ .& ...& .\\ .& & .\\ h_{S_{1}R}^N& ...& h_{S_{N_S}R}^N\end{array}\right)$

Wherein

The expression source node i arrives the channel fading coefficient between the j root antenna of via node, j=1 ..., N.

Demodulating unit 620 is used for described received signal is carried out demodulation, obtains the estimated signal of described source signal.Specifically, demodulating unit 620 is the estimated signal that calculate above-mentioned source signal according to following formula

$\hat{x}\left(t\right)=\underset{x\left(t\right)}{\arg \min }{\left|\right|y_{\mathrm{SR}}\left(t\right)-H_{\mathrm{SR}}x\left(t\right)\left|\right|}^2;$

Obtain having N at last _SThe estimated signal vector of individual element: $\hat{x}\left(t\right)={\left(\begin{array}{ccc}{\hat{x}}_1\left(t\right)& ...& {\hat{x}}_{N_S}\left(t\right)\end{array}\right)}^T.$

Network precoding unit 630 is used for described estimated signal is carried out the network precoding.

At first, network precoding unit 630 is earlier with T _SEstimated signal in the individual time slot constitutes the estimated signal vector $\hat{x}={(\hat{x}\left(t\right),\hat{x}(t+1),...,\hat{x}(t+T_S-1))}^T,$ And then according to m precoding vector P _mWith network code vector θ _RmAbove-mentioned estimated signal vector is carried out the network precoding, obtains m N and tie up sub-information flow: $x_R=(P_1{\mathrm{\&theta;}}_{R1}\hat{x},P_2{\mathrm{\&theta;}}_{R2}\hat{x}...,P_m{\mathrm{\&theta;}}_{\mathrm{Rm}}\hat{x}).$

As shown in Figure 7, as one embodiment of the present of invention, network code unit 630 can comprise vectorial receiver module 631, vectorial acquisition module 632 and precoding module 633, wherein:

Vector receiver module 631 is used for receiving by unlimited feedback channel the sequence number and the precoding vector of the network code vector of destination node feedback; Vector acquisition module 632 is used for obtaining the network code vector according to the sequence number of described network code vector from the set of default network code vector; Precoding module 633 is used for according to described precoding vector and network code vector described estimated signal being carried out the network precoding.Here, feedback channel is unlimited feedback channel, thus destination node to network code unit 630 feedback be the sequence number and the precoding vector of network code vector, similar about obtaining of these two kinds of vectors with the description of the corresponding embodiment of Fig. 3, no longer give unnecessary details.

As an alternative embodiment of the invention, vector is accepted module 631 and also is used for receiving the sequence number of network code vector of destination node feedback and the sequence number of precoding vector by the Limited Feedback channel; Vector acquisition module 632 also is used for obtaining precoding vector according to the sequence number of described precoding vector from default precoding vector set.Promptly when feedback channel is the Limited Feedback channel, destination node is the sequence number of network code vector and the sequence number of precoding vector to network code unit 630 feedbacks, and obtains required network code vector sum precoding vector by network code unit 630 according to this sequence number.

Transmitting element 640 is used for and will be sent to destination node through the signal behind the described network precoding unit coding.Destination node can be by following manner to x _RDecode:

At first, because the broadcast characteristic of wireless signal, destination node is the same with via node, also can receive source node S ₁-S _NsThe signal that is sent also has N root antenna at this hypothesis goal node, and its source node signal of receiving is designated as y _SD(t), then:

y _SD(t)＝H _SDx(t)+n _SD(t)；

Wherein, $x\left(t\right)={({\mathrm{\&theta;}}_1{x}_1\left(t\right),...,{\mathrm{\&theta;}}_{N_S}{x}_{\mathrm{Ns}}\left(t\right))}^T$ Expression N _SThe signal that individual source node sends in t time slot; n _SD(t) white Gaussian noise between source node and the destination node; H _SDExpression N _SChannel fading matrix between individual source node and the destination node D:

$H_{\mathrm{SD}}=\left(\begin{array}{ccc}{h}_{S_{1}D}^1& ...& h_{S_{N_S}D}^1\\ .& & .\\ .& ...& .\\ .& & .\\ h_{S_{1}D}^N& ...& h_{S_{N_S}D}^N\end{array}\right)$

Wherein

Represent source node i to the channel fading coefficient between the j root antenna of destination node, j=1 ..., N;

Then, destination node is according to its source node signal y that receives _SD(t) and via node transmit through the signal x behind the network code _R, decoding obtains needed signal.

The embodiment of the invention is carried out the network precoding by via node to the signal that source node sent, thereby makes that the transfer of data of multiuser MIMO trunk channel has higher throughput in the cordless communication network, and efficiency of transmission has obtained effective raising.

Be illustrated in figure 8 as the structural representation of a kind of device that the embodiment of the invention provides, this device comprises: source signal receiving element 810, decoding unit 820 and code signal receiving element 830, wherein decoding unit 820 links to each other with source signal receiving element 810 and code signal receiving element 830 respectively.

Source signal receiving element 810 is used to receive the source signal that at least two source nodes send, and obtains received signal.Suppose that the destination node D among Fig. 1 has N root antenna, then destination node D can receive following signal at time slot t:

y _SD(t)＝H _SDx(t)+n _SD(t)；

Wherein, $x\left(t\right)={({\mathrm{\&theta;}}_1{x}_1\left(t\right),...,{\mathrm{\&theta;}}_{N_S}{x}_{\mathrm{Ns}}\left(t\right))}^T$ Expression N _SThe signal that individual source node sends in t time slot; n _SD(t) expression N _SWhite Gaussian noise between individual source node and the destination node D; H _SDExpression N _SChannel fading matrix between individual source node and the destination node D, and

$H_{\mathrm{SD}}=\left(\begin{array}{ccc}{h}_{S_{1}D}^1& ...& h_{S_{N_S}D}^1\\ .& & .\\ .& ...& .\\ .& & .\\ h_{S_{1}D}^N& ...& h_{S_{N_S}D}^N\end{array}\right);$

Wherein Represent source node i to the channel fading coefficient between the destination node j root antenna, j=1 ..., N.

Code signal receiving element 830 is used to receive that via node sends through the precoded signal after the network precoding.Specifically, be that via node carries out the network precoding to the signal that its source node that receives sends, and then the data after the precoding sent to code signal receiving element 830 that this network precoding process can be referring to describing accordingly among Fig. 6 embodiment.

Decoding unit 820 is used for decoding to obtain desired signal, such as carrying out maximum likelihood decoding according to above-mentioned received signal and precoded signal according to above-mentioned received signal and precoded signal.

See also Fig. 9, as one embodiment of the present of invention, this device can also comprise precoding vector generation unit 840, network code vector generation unit 850 and feedback unit 860.

Wherein, network code vector generation unit 850 is used to choose inverse FFT IFFT matrix, and obtains the network code vector according to described precoding vector and according to the principle of channel capacity maximum from the IFFT matrix.

And precoding vector generation unit 840 is used to obtain precoding vector, and feedback unit 860 is used for to via node feedback precoding vector and network code vector, and still, according to the difference of feedback channel type, the concrete effect of said two units is also different.

When feedback channel is unlimited feedback channel: precoding vector generation unit 840 be used for to and via node between the channel fading matrix carry out the signal to noise ratio that singular value decomposition is calculated each parallel sub-channels, and just greater than the pairing characteristic vector of characteristic value of default thresholding signal to noise ratio as precoding vector.This moment, feedback unit 860 was that sequence number and precoding vector with the network code vector feeds back to via node.

When feedback channel was the Limited Feedback channel: precoding vector generation unit 840 specifically was used for choosing precoding vector according to the principle of minimal error bit probabilities from default precoding vector set.Feedback unit 860 then is that the sequence number with the sequence number of network code vector and precoding vector feeds back to via node.

The embodiment of the invention is carried out the network precoding by via node to the signal that source node sent, thereby makes that the transfer of data of multiuser MIMO trunk channel has higher throughput in the cordless communication network, and efficiency of transmission has obtained effective raising.

The system construction drawing that provides for the embodiment of the invention as shown in figure 10, this system comprises source node 1001, relaying 1002 and destination node 1003, wherein, relaying 1002 links to each other with source node 1001 and destination node 1003 respectively by Radio Link.

Source node 1001 can comprise that in the present embodiment mobile phone, personal digital assistant PDA, PC etc. can carry out the electronic equipment of radio communication, and in the present embodiment, source node 1001 comprises above-mentioned two equipment at least.

Relaying 1002 and destination node 1003 all are multi-antenna, and source node 1001 sends signal by relaying 1002 to destination node 1003.Specifically, relaying 1002 can comprise described a kind of relaying as above-mentioned embodiment, and destination node 1003 can comprise the described a kind of device of the foregoing description, such as a kind of base station.For the concrete course of work of this system, described in previous embodiment.

Specify the beneficial effect of the embodiment of the invention at last by several emulation experiments:

Since the embodiment of the invention with via node at T _SEstimated signal in the individual time slot finish through transmitting in a time slot after the network precoding processing, so its throughput can reach T _S/ (T _S+ 1), can be with T _SIncrease and improve, so the embodiment of the invention has the advantage of high-throughput.

In addition, the embodiment of the invention also has the advantage of higher coding gain.Be that the network pre-coding scheme of the embodiment of the invention and the performance of complex field network code compare as shown in figure 11, its simulation parameter is as follows:

(1) in the network pre-coding scheme, two source nodes, a via node and a destination node, the antenna number of source node is 1, and via node and destination node antenna number are 2, and the number of precoding vector and network code vector is 1, symbol numbers T _S=1, promptly throughput is 1/2 symbol/information source/time slot;

(2) in the complex field network code, two source nodes, two via nodes and a destination node, all nodes all are antennas, throughput is 1/2 symbol/information source/time slot;

(3) suppose that channel is a symmetric channel, promptly source node to via node, source node to destination node and via node be separate fading channel to the channel of destination node, and the received signal to noise ratio of hypothesis goal node and via node is identical;

(4) source node and via node all adopt the BPSK modulation system.

As seen from Figure 11, adopt the scheme of the scheme ratio complex territory network code of network precoding that tangible coding gain is arranged, such as when the wrong bitrate BER=10-4, the scheme of the embodiment of the invention has the coding gain of nearly 10dB than existing complex field network code.

Next be that the performance of network pre-coding scheme under different throughput situations compares, see also Figure 12, the simulation parameter here is as follows:

(1) in the network pre-coding scheme, two source nodes, a via node and a destination node, the antenna number of source node is 1, via node and destination node antenna number are 2, T _SGet 1,3 and 4 respectively, corresponding throughput is respectively 1/2 symbol/information source/time slot, 3/4 symbol/information source/time slot and 4/5 symbol/information source/time slot;

(2) suppose that channel is a symmetric channel, promptly source node to via node, source node to destination node and via node be separate fading channel to the channel of destination node, and the received signal to noise ratio of hypothesis goal node and via node is identical;

(3) source node and via node all adopt the BPSK modulation system.

As can be seen from Figure 12, when little signal to noise ratio snr, along with the increase of throughput, the performance of network pre-coding scheme runs down, but its amplitude of variation is not very big, and along with the increase gradually of SNR, the performance of several schemes reaches unanimity gradually.

This is that the improvement of destination node performance relies on via node to a great extent extra diversity is provided, and must cause more mistake and merge multidata at via node because when little signal to noise ratio, the influence of channel additive noise (white Gaussian noise) is bigger.Along with the increase of signal to noise ratio, what produce in the channel is wrong less, and the destination node only information of the reception sources node probability that can recover initial data increases, and the dependence of via node is reduced, thereby the performance of several schemes is reached unanimity.

As seen, this programme is when having high-throughput, within scope that can also being controlled at of wrong bitrate is certain.

One of ordinary skill in the art will appreciate that all or part of flow process that realizes in the foregoing description method, can instruct relevant hardware to finish by computer program, described program can be stored in the computer read/write memory medium, this program can comprise the flow process as the embodiment of above-mentioned each side method when carrying out.Wherein, described storage medium can be magnetic disc, CD, read-only storage memory body (Read-Only Memory, ROM) or at random store memory body (Random Access Memory, RAM) etc.

Above-described embodiment; purpose of the present invention, technical scheme and beneficial effect are further described; institute is understood that; the above only is the specific embodiment of the present invention; and be not intended to limit the scope of the invention; within the spirit and principles in the present invention all, any modification of being made, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (13)

1. a data transmission method is characterized in that, described method comprises:

Receive the source signal that at least two source nodes send, obtain received signal;

Described received signal is decoded, obtain the estimated signal of described source signal;

Described estimated signal is carried out the network precoding, and precoded signal is sent to destination node.

2. the method for claim 1 is characterized in that, describedly described estimated signal is carried out the network precoding comprises:

Receive the sequence number and the precoding vector of the network code vector of destination node feedback by unlimited feedback channel;

Choose the network code vector according to the sequence number of described network code vector;

According to described precoding vector and network code vector described estimated signal is carried out the network precoding.

3. the method for claim 1 is characterized in that, describedly described estimated signal is carried out the network precoding comprises:

Receive the sequence number of network code vector of destination node feedback and the sequence number of precoding vector by the Limited Feedback channel;

Choose the network code vector according to the sequence number of described network code vector, and choose precoding vector according to the sequence number of described precoding vector;

According to described precoding vector and network code vector described estimated signal is carried out the network precoding.

4. a data transmission method is characterized in that, described method comprises:

Receive the source signal that at least two source nodes send, obtain received signal;

Receive the precoded signal that via node sends, described precoded signal is decoded to the received signal that the source signal that sends according to described at least two source nodes obtains by described via node, obtain estimated signal, and estimated signal is carried out the network precoding obtain;

Decode according to described received signal and described precoded signal.

5. method as claimed in claim 4 is characterized in that, also comprises before the precoded signal that described reception via node sends:

To and described via node between the channel fading matrix carry out singular value decomposition, obtain the signal to noise ratio of parallel sub-channels;

Will be greater than the pairing characteristic vector of signal to noise ratio of presetting thresholding as precoding vector;

Choose inverse FFT IFFT matrix, from described IFFT matrix, obtain the network code vector according to described precoding vector;

The sequence number and the described precoding vector of described network code vector are fed back to described via node by unlimited feedback channel.

6. method as claimed in claim 4 is characterized in that, what described reception via node sent also comprises through the code signal after the network precoding before:

From the precoding vector set, choose precoding vector;

Choose the IFFT matrix, and from described IFFT matrix, obtain the network code vector according to described precoding vector;

Give described via node with the sequence number of described precoding vector and the sequence number of described network code vector by the Limited Feedback channel feedback.

7. a relaying is characterized in that, comprising:

The source signal receiving element is used to receive the source signal that at least two source nodes send, and obtains received signal;

Decoding unit is used for described received signal is decoded, and obtains the estimated signal of described source signal;

The network precoding unit is used for described estimated signal is carried out the network precoding;

Transmitting element is used for and will be sent to destination node through the signal after the precoding of described network precoding unit.

8. relaying as claimed in claim 7 is characterized in that, described network precoding unit comprises:

The vector receiver module is used for sequence number and precoding vector by the network code vector of unlimited feedback channel reception destination node feedback;

The vector acquisition module is used for obtaining the network code vector according to the sequence number of described network code vector;

Precoding module is used for according to described precoding vector and network code vector described estimated signal being carried out the network precoding.

9. relaying as claimed in claim 8 is characterized in that,

Described vector is accepted module, also is used for receiving the sequence number of network code vector of destination node feedback and the sequence number of precoding vector by the Limited Feedback channel;

Described vectorial acquisition module also is used for obtaining precoding vector according to the sequence number of described precoding vector.

10. a device is characterized in that, comprising:

The source signal receiving element is used to receive the source signal that at least two source nodes send, and obtains received signal;

The code signal receiving element, be used to receive the precoded signal that via node sends, described precoded signal is decoded to the received signal that the source signal that sends according to described at least two source nodes obtains by described via node, obtain estimated signal, and estimated signal is carried out the network precoding obtain;

Decoding unit is used for decoding according to described received signal and described precoded signal.

11. device as claimed in claim 10 is characterized in that, also comprises:

The precoding vector generation unit, be used for to and described via node between the channel fading matrix carry out the signal to noise ratio that singular value decomposition is calculated each parallel sub-channels, and will be greater than the pairing characteristic vector of signal to noise ratio of default thresholding as precoding vector;

Network code vector generation unit is used to choose inverse FFT IFFT matrix, and obtains the network code vector according to described precoding vector from described IFFT matrix;

Feedback unit is used for described precoding vector and described network code vector are fed back to described via node by unlimited feedback channel.

12. device as claimed in claim 10 is characterized in that,

Described precoding vector generation unit also is used for choosing precoding vector from the precoding vector set;

Feedback unit also is used for giving described via node with described precoding vector and described network code vector by the Limited Feedback channel feedback.

13. a data transmission system is characterized in that, comprises as the arbitrary described relaying of claim 7-9, as the arbitrary described device of claim 10-12 and at least two source nodes, described source node is used for sending data to described relaying and described device.

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