CN102739383A - Method for allocating union resource based on limited feedback OFDM-AF (Orthogonal Frequency Division Multiplexing-Audio Frequency) system - Google Patents

Abstract

The invention discloses a method for allocating union resource based on a limited feedback OFDM-AF (Orthogonal Frequency Division Multiplexing-Audio Frequency) system. The method comprises the following steps: a resource allocation policy code book necessary for limited feedback is designed, wherein each code word in the code book is an independent complete power allocation and sub-carrier matching scheme; an information destination D matches an estimation value with the designed code book based on the channel estimation to a communication system, and carries out ergodic search and selects an optimal code word in the code book; the information destination D broadcasts a subscript with the optimal code word; and an information source S and a relay R with the same code book transcripts transmit corresponding code words in accordance with the received subscripts respectively. With the adoption of the method, the system performance can be improved greatly under the condition of extremely few feedback bits; the performance loss when a transmitter has no channel information is made up; and meanwhile the defect that the complete channel information feedback in a traditional OFDM system cannot be realized is overcome; and the method is applicable to more practical communication scenes.

Description

Based on the system combined resource allocation methods of the OFDM-AF of Limited Feedback

Technical field

The present invention relates to the federated resource distribution method of wireless communication field, specifically is that (Amplify-and-Forward, AF) federated resource based on Limited Feedback distributes in the relaying diversity system in OFDM amplification-forwarding.

Background technology

Be accompanied by people to the improving constantly of communicating requirements such as high accuracy, high reliability, strong flexibility, solve owing to its non-ideal characteristic problems such as complicated more various serious decline that causes of the continuous expansion of communication range and communication environment and intersymbol interference just seem particularly important.Its immediate solution is exactly in wireless communication system, to adopt the Radio Transmission Technology that spectrum efficiency is higher, the anti-multipath interference performance is stronger.In multiple wireless solution, with the relaying technique that can significantly improve power system capacity with OFDM be representative multi-carrier modulation technology with can show one's talent.In the relaying cooperation communication system, information source is when message is sent in the stay of two nights, and via node also can receive this message simultaneously, after it is directly amplified the recompile of perhaps decoding, is transmitted to the stay of two nights.The stay of two nights is united the message of utilizing all to receive again and is decoded.Junction network is equal to and need disposing under the condition of many antennas, and certain relaying collaboration diversity is provided, and when enlarging communication, has improved communication quality.Based on the availability of frequency spectrum of OFDM technique to high-efficiency, and superior anti-multipath decline ability, become the physical layer key technology of future mobile communication system based on the relaying technique of OFDM modulation.

Based on the finiteness of system's transmitted power budget, and the independence of the decline of the sub-carrier channels in the multi-hop in the junction network, power division and subcarrier coupling have become problem demanding prompt solution in the OFDM relay system.

Yet, no matter be power division, or be the subcarrier coupling, all need under the prerequisite that obtains network channel information, could realize.Because the complexity of communication environment and the mobility at random at terminal, power allocation vector and subcarrier matching vector must change along with the change of channel status.Because traditional channel reciprocity method is no longer proved effective in the carrier frequency subsystem, what current industry was mainly considered is through reverse link forward channel status information to be fed back to transmitting terminal.But in multicarrier system; Owing to there be circuitous the hysteresis, the restriction of factors such as capacity that channel estimation errors, based on feedback link are limited and the restriction of code book scale, the complete channel information feedback is difficult to realize; The proposition of Limited Feedback technology has overcome this problem effectively.

Because the inherent distributed nature of relaying collaborative network, the Limited Feedback research that is directed to the OFDM junction network is also also immature.

N.Zhou and X.Zhu etc. are in 2009 IEEE International Conference on Communications meeting article " Dynamic Resource Allocation with Limited Feedback for OFDM Based CooperativeNetworks "; Considered a kind of asymmetric relay transmission structure based on Limited Feedback; Increased the degree of freedom that system power distributes, but the author has only considered power division to this model.They are again in the paper of above-mentioned achievement being expanded to IEEETrans. ~ Commun. periodical in 2010 " Optimal asymmetric resource allocation with limited feedback for OFDM based relay systems ".People such as Hajiaghayi are in IEEE International Conference on Communications meeting paper " Using Limited Feedback in Power Allocation Design for a Two-Hop Relay OFDM System " in 2009; Power division based on the double bounce AF junction network of OFDM modulation has been discussed, the author respectively with maximized system capacity with minimize error sign ratio and come algorithm for design as target.Although the document is not discussed to the subcarrier coupling of double bounce, its thought based on the Lloyd algorithm is extensively adopted.Utilize similar methods; Proposed similar power distribution algorithm in the article " Power Allocation in Decode-and-Forward Cooperative OFDM Systems Using Perfect and Limited Feedback " of Zhang on Chinese Journal of Electronics, but it discusses the DF junction network that object is based on OFDM.F.Li; The relay selection scheme based on Limited Feedback discussed in the article that people such as X.Ke deliver in 2010 IEEE Youth Conference on Information Computing and Telecommunications meetings " A relay selection scheme with limit feedback in OFDM relay networks based onsubcarrier mapping "; Although the document has related to the coupling of subcarrier, the author does not have power division limited in the analytical system.Liu Yonghe Chen Wen has considered the power division based on the AF network of Limited Feedback in 2011 in IEEE International Conference on Communications meeting article " Capacity Based Adaptive Power Allocation for the OFDM Relay Networks with Limited Feedback "; But in this piece document, the author does not consider the subcarrier coupling.

Summary of the invention

The objective of the invention is to overcome the deficiency of prior art; Federated resource distribution method based on Limited Feedback is provided in a kind of OFDM amplification-forwarding (AF) relaying diversity system; This method utilizes iteration Lloyd algorithm that the channel matrix space is divided into independently subspace; The method of utilizing integer restriction serialization and Lagrange duality to decompose; Dexterously mixed integer programming problem to be optimized is found the solution, and constructed algorithm center criterion based on this, finally the feedback through stay of two nights limit bit realizes that system power distributes and the subcarrier coupling.The present invention has characteristics such as real-time operation is simple, complexity is low, overhead is few, and data show the bit number that only needs seldom, just can remedy the performance loss of system's overwhelming majority.

Relaying diversity system of the present invention is a kind of single antenna communication system, and this communication system is made up of three nodes, i.e. 1 information source S, 1 AF relaying R and 1 stay of two nights D.Information source, the stay of two nights and relaying are the single antenna configuration.The present invention also supposes to exist direct link between the information source and the stay of two nights.The stay of two nights sends to information source and relaying through based on feedback link with subscript after the subscript that chooses the resource allocation vector.

In order to make full use of the extra channel degree of freedom that relaying brings, the whole transmission course of collaborative network of the present invention is divided into two time slots.Information source is at the first time slot radio transmission signal, and the stay of two nights and relaying receive respectively, and both receive signal and are:

$y_{\mathrm{rm}}=\sqrt{P_S^m}{h}_{\mathrm{SR}}^m{s}_m+z_{\mathrm{rm}},$

$y_{\mathrm{dm}}^{\left(1\right)}=\sqrt{P_S^m}{h}_{\mathrm{SD}}^m{s}_m+z_{\mathrm{dm}}^{\left(1\right)},$

The noise introduced for each node of z wherein, subscript " 1 " expression first time slot.In second time slot, S keeps quite, and relaying R is to y _RmAmplify the back and transmit, the stay of two nights receives, and its reception signal is:

$y_{\mathrm{dn}}^{\left(2\right)}=\sqrt{\frac{P_R^n}{P_S^m{\left|h_{\mathrm{SR}}^m\right|}^2+{\mathrm{\σ}}_r^2}}{h}_{\mathrm{RD}}^n{y}_{\mathrm{rm}}+z_{\mathrm{dn}}^{\left(2\right)},$

The signal that the stay of two nights receives two time slots carries out high specific and merges (MRC), and the signal of receiving in two time slots is merged, and signal is sent in the decoding reduction again.In addition, another work of the stay of two nights is the instantaneous channel condition information that estimates according to it, in preset resource allocation code book, searches optimum code word, and its subscript is fed back to transmitting terminal.

The present invention adopts following technical scheme to realize:

The system combined resource allocation methods of a kind of OFDM-AF based on Limited Feedback may further comprise the steps:

Step 1: the design of federated resource allocation strategy code book: each code word in the code book is a kind of independent, perfect power division and subcarrier matching scheme; Decompose through integer restriction serialization and Lagrange duality; Dexterously former mixed integer programming problem is found the solution, and constructed the center criterion of Lloyd algorithm with this;

Step 2: stay of two nights D is according to all channel matrixes of estimating to know; Through channel status estimated value and resource allocation code book are mated; Traversal search is selected optimum code word in the resource allocation code book of current optimal, and promptly optimum power is distributed and the subcarrier matching scheme, writes down this code word subscript;

Step 3: stay of two nights D broadcasts optimum code word subscript, and information source S and via node R with same codebook copy receive simultaneously;

Step 4: information source S distributes and the subcarrier matching scheme according to the optimum power that step 1 is pointed out, and carries out the transmission of modulated signal sequences;

Step 5: relaying R carries out processing and amplifying to the received signal of step 2 according to the factor

, transmits to stay of two nights D then;

Step 6: stay of two nights D merges (MRC) through the signal of receiving in two time slots being carried out high specific, and signal is sent in reduction, and simultaneously that channel condition information in this transmission course is corresponding optimum code word subscript is carried out feedback processing.

Optimum code word described in the step 2

procurement process is following:

In the AF cooperating relay network limited based on system's gross power, corresponding to subcarrier to (m, achievable rate n) is approximately:

$R_{m,n}\≈\frac{1}{2}{\log }_2(1+P_S^m{\mathrm{\γ}}_{\mathrm{SD}}^m+\frac{P_S^m{P}_R^n{\mathrm{\γ}}_{\mathrm{SR}}^m{\mathrm{\γ}}_{\mathrm{RD}}^n}{P_S^m{\mathrm{\γ}}_{\mathrm{SR}}^m+P_R^n{\mathrm{\γ}}_{\mathrm{RD}}^n}),$

As target function, system's gross power is limited as condition with maximum this achievable rate, can obtain, at subcarrier to (m, n) gross power does

The time, maximum achievable rate R ^* _{M, n}For:

$R_{m,n}^{*}=\left\{\begin{array}{ccc}\frac{1}{2}{\log }_2(1+\frac{{\mathrm{\&gamma;}}_{\mathrm{SD}}^m\mathrm{\&mu;}({\mathrm{\&gamma;}}_{\mathrm{SR}}^m\mathrm{\&mu;}+{\mathrm{\&gamma;}}_{\mathrm{RD}}^n)+{\mathrm{\&gamma;}}_{\mathrm{SR}}^m{\mathrm{\&gamma;}}_{\mathrm{RD}}^n\mathrm{\&mu;}}{(1-\mathrm{\&mu;})({\mathrm{\&gamma;}}_{\mathrm{SR}}^m\mathrm{\&mu;}+{\mathrm{\&gamma;}}_{\mathrm{RD}}^n)}{P}_{m,n})& \mathrm{if}& {\mathrm{\&gamma;}}_{\mathrm{SD}}^m<{\mathrm{\&gamma;}}_{\mathrm{RD}}^n,\\ \frac{1}{2}{\log }_2(1+{\mathrm{\&gamma;}}_{\mathrm{SD}}^m{P}_{m,n}),& \mathrm{if}& {\mathrm{\&gamma;}}_{\mathrm{SD}}^m\&GreaterEqual;{\mathrm{\&gamma;}}_{\mathrm{RD}}^n.\end{array}\right.$

If definition equivalent channel gain

${\stackrel{\&OverBar;}{\mathrm{\&gamma;}}}^{m,n}=\left\{\begin{array}{cc}\frac{{\mathrm{\&gamma;}}_{\mathrm{SD}}^m\mathrm{\&mu;}({\mathrm{\&gamma;}}_{\mathrm{SR}}^m\mathrm{\&mu;}+{\mathrm{\&gamma;}}_{\mathrm{RD}}^n)+{\mathrm{\&gamma;}}_{\mathrm{SR}}^m{\mathrm{\&gamma;}}_{\mathrm{RD}}^n\mathrm{\&mu;}}{(1+\mathrm{\&mu;})({\mathrm{\&gamma;}}_{\mathrm{SR}}^m\mathrm{\&mu;}+{\mathrm{\&gamma;}}_{\mathrm{RD}}^n)},& {\mathrm{\&gamma;}}_{\mathrm{SD}}^m<{\mathrm{\&gamma;}}_{\mathrm{RD}}^n,\\ {\mathrm{\&gamma;}}_{\mathrm{SD}}^m,& {\mathrm{\&gamma;}}_{\mathrm{SD}}^m\&GreaterEqual;{\mathrm{\&gamma;}}_{\mathrm{RD}}^n\end{array}\right.$

R _{M, n}Can unify to be expressed as

Form.To integer restrictive condition t _{M, n}{ 0,1}'s ∈ relaxes extremely

Afterwards, make subcarrier matching attribute t _{M, n}Become the right time domain of each subcarrier of system and share the factor, then this moment, former optimization problem can become

$\underset{\{S,t\}}{\max }\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{t}_{m,\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="DEST\_PATH\_HDA00001923150300031.png,HDA00001692195000021.png"\; state="\{\{state\}\}">n</figure-callout>}}\frac{1}{2}{\log }_2(1+S_{m,n}\frac{{\stackrel{\&OverBar;}{\mathrm{\&gamma;}}}^{m,n}}{t_{m,n}}),$

$s.t.t_{m,n}\&GreaterEqual;0,\&ForAll;m,n,\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{S}_{m,n}\&le;P_t,S_{m,n}\&GreaterEqual;0,\&ForAll;m,n,$

$\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}{t}_{m,n}=1,\&ForAll;n,\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{t}_{m,n}=1,\&ForAll;m,$

S wherein _{M, n}=t _{M, n}P _{M, n}The finger system at subcarrier to (m, the actual power that is consumed in n).The present invention carries out the dualization operation with restrictive condition

and

, can construct Lagrangian and be:

$L(S,t,\mathrm{\&alpha;},\mathrm{\&beta;})=\frac{1}{2}\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{t}_{m,n}{\log }_2(1+S_{m,n}\frac{{\stackrel{\&OverBar;}{\mathrm{\&gamma;}}}^{m,n}}{t_{m,n}})+\mathrm{\&alpha;}(P_t-\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{S}_{m,n})+\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_m(1-\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{t}_{m,n}),$

α>=0 and β=(β wherein ₁, β ₂..., β _N)>=0 is a dual variable.At this moment, dual objective function and dual problem thereof are respectively:

$g(\mathrm{\&alpha;},\mathrm{\&beta;})=\underset{\{S,t\}}{\max }L(S,t,\mathrm{\&alpha;},\mathrm{\&beta;}),s.t.\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}{t}_{m,n}=1,\&ForAll;n,t_{m,n}\&GreaterEqual;0,\&ForAll;m,n,\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{S}_{m,n}\&le;P_t,$

$\underset{\{\mathrm{\&alpha;},\mathrm{\&beta;}\}}{\min }g(\mathrm{\&alpha;},\mathrm{\&beta;})s.t.\mathrm{\&alpha;}\&GreaterEqual;0,\mathrm{\&beta;}\&GreaterEqual;0.$

Find the solution to such an extent that optimal power allocation vector and optimum subcarrier matching attribute are respectively:

$S_{m,n}^{*}=t_{m,n}{[\frac{1}{2\mathrm{\&alpha;}}-\frac{1}{{\stackrel{\&OverBar;}{\mathrm{\&gamma;}}}^{m,n}}]}^{+},$ $t_{m,n}^{*}=\left\{\begin{array}{cc}1& m=\arg \underset{m=1,...,N}{\max }{T}_{m,n},\\ 0& \mathrm{otherwise}.\end{array}\right.$

For dual problem, can obtain the dual variable value through gradient descent method iteration:

$\left\{\begin{array}{cc}{\mathrm{\&alpha;}}^{(i+1)}={\mathrm{\&alpha;}}^{\left(i\right)}-a^{\left(i\right)}(P_t-\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{S}_{m,n}^{\left(i\right)}),& \\ {\mathrm{\&beta;}}_m^{(i+1)}={\mathrm{\&beta;}}_m^{\left(i\right)}-b^{\left(i\right)}(1-\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{t}_{m,n}^{\left(i\right)}),& m=1,...,N,\end{array}\right.$

Wherein, i is an iterations, a ⁽ⁱ⁾And b ⁽ⁱ⁾Be iteration step length.Based on the α and the β that obtain in the iteration each time _m, we can upgrade optimal power allocation vector and optimum subcarrier matching attribute, until algorithmic statement, export optimal power allocation vector and optimum subcarrier matching attribute, and construct optimum code word with this.

Operation principle of the present invention:

In relaying cooperative system based on the OFDM modulation; Because the sub-channel amount of information is various; The restriction of factors such as capacity that based on feedback link is limited and the restriction of code book scale makes feedback of channel information be difficult to realize, and then limited the carrying out that the power division in the real system and subcarrier mate.The present invention adopts the technology of Limited Feedback, through the design to the feedback code book, represents complete resource allocation vector with few feedback bits, thereby realizes the dynamic assignment of subcarrier and power.The present invention adopts the Lloyd algorithm to construct the required resource allocation code book of feedback.In design part for the center criterion, utilize the time domain sharing characteristic of multicarrier system, former mixed integer programming problem is carried out integer restriction serialization, and adopt the optimization problem after the Lagrange duality method is found the solution processing.Through the center criterion and the most mutual iteration of contiguous criterion, the optimal resource allocation vector that the convergence back obtains is the prototype of code word in the optimum code book.

Compared with prior art, the present invention has considered application scenarios more actual in the radio communication, dynamic sub carrier coupling and power division promptly can't obtain complete channel information at the sending node place time.Compare with power distribution strategies with existing joint subcarrier coupling, only needing very, the feedback of limit bit number just can remedy the most performance gain of system.

Description of drawings

Fig. 1 is the trunk channel system block diagram based on feedback.

Fig. 2 is the iterative process sketch map of Lloyd algorithm.

Fig. 3 is a Lloyd convergence of algorithm performance.

Fig. 4 is distinct methods comparison on the end-to-end speed of system in given signal to noise ratio scope.

Fig. 5 is the comparison of method end-to-end speed of system when different number of bits of feedback.

Fig. 6 for method when number of sub carrier wave changes, the comparison of the end-to-end speed of system that diverse ways can be obtained.

Among Fig. 4, Fig. 6:

Carry out average power allocation on the basis of the no subcarrier coupling of EPA w/o SP representative;

Carry out optimal power allocation on the basis of the no subcarrier coupling of OPA w/o SP representative;

Carry out average power allocation on the basis that on behalf of optimum subcarrier, EPA with SP then mate.

Embodiment

Below in conjunction with accompanying drawing and simulation example embodiments of the invention are elaborated: present embodiment is that prerequisite is implemented with technical scheme of the present invention; Provided detailed execution mode and concrete operating process, but protection scope of the present invention is not limited to following embodiment.

Like the OFDM AF trunk channel in the accompanying drawing 1, relaying amplifies forwarding with the signal that receives.System adopts the QPSK modulation system.The channel gain of all sub-carrier channels remains unchanged in the transmission course of two complete time slots, and the equal Rayleigh distributed of each sub-carrier channels, the path loss factor are 3.The noise hypothesis is obeyed

Gradient descent method iteration step length does

The scale of channel status collection is 10 ⁴In the emulation, every prescription case is all carried out l-G simulation test 10,000 times.Each test is carried out according to following steps:

1: according to maximum system rate criterion design resource feedback code book, its code word is made up of power allocation vector and subcarrier matching attribute.At first construct optimization problem, restrictive condition is the integer attribute that system's gross power is limited and subcarrier matees; Integer condition through serialization subcarrier coupling is converted into solution Lagrange duality resolution problem with problem; The closed solutions of optimal power allocation and optimum subcarrier coupling when optimizing this dual objective function and corresponding dual problem thereof and obtaining set channel status.Initialization Lloyd algorithm parameter comprises the channel status collection H={h that defines great scale then _l, l=1 ..., M}, definition iteration step length and constant ε.The midamble code collection T={c (h) that then answers from the channel status set pair | choose the h ∈ H} that B code word constitutes initial codebook and realize the iteration that replaces of the most contiguous criterion and center criterion based on this code book; When the distortion factor satisfied

of algorithm; Stop iteration, and export optimum code book.

Shown in accompanying drawing 2, code book design and code word renewal process specifically are expressed as:

Step 1: produce a large amount of forward channel matrix h=(h at random _SD, h _SR, h _RD) constitute the sample space H={h_{l} of channel as training sequence, l=1 ..., M}, wherein, $h_{\mathrm{SD}}=({\mathrm{<figure-callout\; id="1"\; label="h\; SD"\; filenames="DEST\_PATH\_HDA00001923150300031.png,HDA00001692195000021.png"\; state="\{\{state\}\}">h</figure-callout>}}_{\mathrm{SD}}^{},...,h_{\mathrm{SD}}^N),$ $h_{\mathrm{SR}}=({\mathrm{<figure-callout\; id="1"\; label="h\; SR"\; filenames="DEST\_PATH\_HDA00001923150300031.png,HDA00001692195000021.png"\; state="\{\{state\}\}">h</figure-callout>}}_{\mathrm{SR}}^{},...,h_{\mathrm{SR}}^N),$ $h_{\mathrm{RD}}=({\mathrm{<figure-callout\; id="1"\; label="h\; RD"\; filenames="DEST\_PATH\_HDA00001923150300031.png,HDA00001692195000021.png"\; state="\{\{state\}\}">h</figure-callout>}}_{\mathrm{RD}}^{},...,h_{\mathrm{RD}}^N)$ Refer to S-D in a certain transmission cycle respectively, the channel status of S-R and R-D, N are the sub-carrier number of this ofdm system;

Step 2: produce initialized code book, i.e. codeword set at random based on the channel matrix sample space

Wherein j is that iterations is got j=0 at this moment, and B is the code book scale, depends on system feedback bit number k, and the relationship of the two is k=log ₂B,

Be code word, wherein

Refer to information source S respectively on m number of sub-carrier channel and the transmitted power of relaying R on n number of sub-carrier channel, t _{M, n}∈ 0,1} is the subcarrier matching attribute, and when its value is 1, subcarrier m and n coupling, otherwise the two does not mate;

Step 3: according to set code book

is the channel matrix spatial division B sub-channel space k=1 that does not overlap mutually; ...; B, and have

$Q_k^j=\{h=h(h_{\mathrm{SD}},h_{\mathrm{SR}},h_{\mathrm{RD}})|\left(R\left(c_k^j\right|h)\right)\&GreaterEqual;\left(R\left(c_l^j\right|h)\right),\&ForAll;l\&Element;\{\mathrm{1,2},...,B\}\},$

Wherein R (c|h) is defined as corresponding to based on channel samples Space H={ h _l, l=1 ..., the end-to-end total speed of arbitrary given channel conditions h among the M} and the system of optimum code word c, it can be tried to achieve through following formula:

$R=\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="DEST\_PATH\_HDA00001923150300031.png,HDA00001692195000021.png"\; state="\{\{state\}\}">N</figure-callout>}}{\mathrm{\&Sigma;}}}\frac{1}{2}{t}_{m,n}{\log }_2(1+P_S^m{\mathrm{\&gamma;}}_{\mathrm{SD}}^m+\frac{P_S^m{P}_R^n{\mathrm{\&gamma;}}_{\mathrm{SR}}^m{\mathrm{\&gamma;}}_{\mathrm{RD}}^n}{P_S^m{\mathrm{\&gamma;}}_{\mathrm{SR}}^m+P_R^n{\mathrm{\&gamma;}}_{\mathrm{RD}}^n}),$

Wherein,

refers to the standardization channel gain on the respective sub link respectively, and has:

${\mathrm{\&gamma;}}_{S,D}^m={\left|h_{\mathrm{SD}}^m\right|}^2/{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="DEST\_PATH\_HDA00001923150300031.png,DEST\_PATH\_HDA00001923150300032.png"\; state="\{\{state\}\}">k</figure-callout>}}^2,$ ${\mathrm{\&gamma;}}_{S,R}^m={\left|h_{\mathrm{SR}}^m\right|}^2/{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="DEST\_PATH\_HDA00001923150300031.png,DEST\_PATH\_HDA00001923150300032.png"\; state="\{\{state\}\}">r</figure-callout>}}^2$ And ${\mathrm{\&gamma;}}_{R,D}^n={\left|h_{\mathrm{RD}}^n\right|}^2/{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="DEST\_PATH\_HDA00001923150300031.png,DEST\_PATH\_HDA00001923150300032.png"\; state="\{\{state\}\}">k</figure-callout>}}^2;$

Step 4: realize the renewal of code book through each code word in the code book is more newly arrived, be updated to corresponding to k code word of new code book

:

$c_k^{j+1}=\arg \underset{c\&Element;T}{\max }{E}_{h\&Element;Q_k}\left(R\left(c\right|h)\right),k=\mathrm{1,2},...,B;$

This step can realize through following calculating:

$\arg \underset{c\&Element;T}{\max }{E}_{h\&Element;Q_k}\left(R\left(c\right|h)\right)=\arg \underset{c\&Element;T}{\max }{E}_{h\&Element;Q_k}\left(\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{t}_{m,\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="DEST\_PATH\_HDA00001923150300031.png,HDA00001692195000021.png"\; state="\{\{state\}\}">n</figure-callout>}}\frac{1}{2}{\log }_2(1+P^{m,n}{\mathrm{\&gamma;}}^{m,n})\right);$

Step 5: the definition error distance function is a distortion function:

And calculate the overall distortion degree of new code book with this;

Step 6: observe algorithm and whether restrain; And if

stops iteration; Export optimum code book code word; Otherwise jump to step 2 until algorithmic statement, wherein ε is a preset minimum numeral.

2: instantaneous channel condition information h=(h is carried out in the stay of two nights _SD, h _SR, h _RD) estimation, and based on this estimated value, the subscript of the code word of maximum end-to-end speed is searched for and obtained having to traversal search in code book

Q is fed back to information source and relaying with the binary coding form.

3: information source S carries out signal according to power division in the pairing code word of q

and optimum subcarrier matching vector

and sends, and via node R and stay of two nights D receive simultaneously.

4: via node R is according to the pairing code word of q

In optimum subcarrier matching vector t _{M, n}Carry out the subcarrier coupling of double bounce, simultaneously according to power

The signal that first time slot is received amplifies, and carries out the signal transmission of second time slot, and have only stay of two nights D to receive this moment.

5: the stay of two nights merges (MRC) through the signal of receiving in two time slots being carried out high specific, and decoding obtains former transmission signal, decodes again.Simultaneously channel condition information in this transmission course is estimated, and the corresponding optimum code word subscript of search is carried out feedback processing then.

In the present embodiment, the communication scenes of setting is: information source S, via node R and stay of two nights D are distributed on the same straight line; Suppose that information source S is 1 to the range normalization between the stay of two nights D, information source S is d to the distance definition between the via node R, and then via node R just is 1-d to the distance of stay of two nights D.Above-mentioned all figure all are attained at d=0.4.According to above-mentioned steps, each has carried out independent l-G simulation test repeatedly 10,000 times, and the total speed of the system that calculates draws like result shown in the drawings.

Can find out that from accompanying drawing 3 in 4 times that carry out were independently added up, the Lloyd algorithm was all just realized convergence in limited number of times (less than 6 times), this shows that algorithm that the present invention carries has certain feasibility.

From accompanying drawing 4, can find out, the federated resource allocative decision of present embodiment, when number of bits of feedback k=3, performance is considerably beyond EPA w/o SP, OPA w/o SP, three kinds of schemes of EPA with SP.This explanation, scheme of the present invention is than there not being when feedback; Performance is greatly improved, and in addition, accompanying drawing 3 can also be found; Performance when total speed of the system that is obtained during number of bits of feedback k=3 and transmitting terminal have ideal communication channel information is more or less the same, this explanation, scheme of the present invention; Only need few overhead, just can remedy the performance loss of the overwhelming majority.The employing that this means the Limited Feedback technology has certain feasibility and frontier nature.Its further excavation and development had positive great realistic significance.

Can find out that from accompanying drawing 5 the federated resource allocative decision of present embodiment only needs few bit feedback, just can realize the significantly lifting of performance.Under 4 bit feedback situation, be 2.5 o'clock for example in system's speed, this Limited Feedback and transmitting terminal have perfect condition information situation and have only-performance difference of 0.7dB.In addition, accompanying drawing 4 it can also be seen that it is more and more littler that number of bits of feedback increases the performance boost amplitude of being brought, this explanation, and scheme of the present invention, number of bits of feedback and code book scale need not set too big.

Can find out from accompanying drawing 6; Continuous increase along with the system subcarrier number; The poor performance of scheme of the present invention and EPA w/o SP, OPA w/o SP, three kinds of schemes of EPA with SP increases gradually, and this is can bring the bigger distribution degree of freedom to cause by bigger number of sub carrier wave.

Although content of the present invention has been done detailed introduction through above-mentioned preferred embodiment, will be appreciated that above-mentioned description should not be considered to limitation of the present invention.After those skilled in the art have read foregoing, for multiple modification of the present invention with to substitute all will be conspicuous.Therefore, protection scope of the present invention should be limited appended claim.

Claims (5)

1. the system combined resource allocation methods of the OFDM-AF based on Limited Feedback is characterized in that, said relay system is a kind of single antenna communication system, and this system comprises an information source S, an amplification-forward relay R, a stay of two nights D; Said method step comprises:

Step 1: the design of federated resource allocation strategy code book: each code word in the code book is a kind of independent, perfect power division and subcarrier matching scheme; Decompose through integer restriction serialization and Lagrange duality; Former mixed integer programming problem is found the solution, and constructed the center criterion of Lloyd algorithm with this;

Step 2: stay of two nights D is according to all channel matrixes of estimating to know; Through channel status estimated value and resource allocation code book are mated; Traversal search is selected optimum code word in the resource allocation code book of current optimal, and promptly optimum power is distributed and the subcarrier matching scheme, writes down this code word subscript;

Step 3: stay of two nights D broadcasts optimum code word subscript, and information source S and via node R with same codebook copy receive simultaneously;

Step 4: information source S distributes and the subcarrier matching scheme according to the optimum power that step 1 is pointed out, and carries out the transmission of modulated signal sequences;

Step 5: relaying R carries out processing and amplifying to the received signal of step 2, transmits to stay of two nights D then;

Step 6: stay of two nights D merges (MRC) through the signal of receiving in two time slots being carried out high specific, attempts to reduce former transmission signal, and simultaneously that channel condition information in this transmission course is corresponding optimum code word subscript is carried out feedback processing.

2. the system combined resource allocation methods of the OFDM-AF based on Limited Feedback according to claim 1; It is characterized in that: stay of two nights D is as the maincenter node; Channel status is estimated and with code book in after the code word coupling; Subscript is fed back to relaying R and information source S, thus the resource allocation factor of decision fl transmission.

3. the system combined resource allocation methods of the OFDM-AF based on Limited Feedback according to claim 1 and 2 is characterized in that, code book design and code word renewal process specifically are expressed as:

Step 1: produce a large amount of forward channel matrix h=(h at random _SD, h _SR, h _RD) constitute the sample space H={h_{l} of channel as training sequence, l=1 ..., M}, wherein, $h_{\mathrm{SD}}=(h_{\mathrm{SD}}^1,...,h_{\mathrm{SD}}^N),$ $h_{\mathrm{SR}}=(h_{\mathrm{SR}}^1,...,h_{\mathrm{SR}}^N),$ $h_{\mathrm{RD}}=(h_{\mathrm{RD}}^1,...,h_{\mathrm{RD}}^N)$ Refer to S-D in a certain transmission cycle respectively, the channel status of S-R and R-D, N are the sub-carrier number of this ofdm system;

Step 2: produce initialized code book, i.e. codeword set at random based on the channel matrix sample space

Wherein j is that iterations is got j=0 at this moment, and B is the code book scale, depends on system feedback bit number k, and the relationship of the two is k=log ₂B,

Be code word, wherein

Refer to information source S respectively on m number of sub-carrier channel and the transmitted power of relaying R on n number of sub-carrier channel, t _{M, n}∈ 0,1} is the subcarrier matching attribute, and when its value is 1, subcarrier m and n coupling, otherwise the two does not mate;

Step 3: according to set code book

is the channel matrix spatial division B sub-channel space k=1 that does not overlap mutually; ...; B, and have

$Q_k^j=\{h=h(h_{\mathrm{SD}},h_{\mathrm{SR}},h_{\mathrm{RD}})|\left(R\left(c_k^j\right|h)\right)\&GreaterEqual;\left(R\left(c_l^j\right|h)\right),\&ForAll;l\&Element;\{\mathrm{1,2},...,B\}\},$

Wherein R (c|h) is defined as corresponding to based on channel samples Space H={ h _l, l=1 ..., the end-to-end total speed of arbitrary given channel conditions h among the M} and the system of optimum code word c, it is tried to achieve through following formula:

$R=\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}\frac{1}{2}{t}_{m,n}{\log }_2(1+P_S^m{\mathrm{\&gamma;}}_{\mathrm{SD}}^m+\frac{P_S^m{P}_R^n{\mathrm{\&gamma;}}_{\mathrm{SR}}^m{\mathrm{\&gamma;}}_{\mathrm{RD}}^n}{P_S^m{\mathrm{\&gamma;}}_{\mathrm{SR}}^m+P_R^n{\mathrm{\&gamma;}}_{\mathrm{RD}}^n}),$

Wherein,

refers to the standardization channel gain on the respective sub link respectively, and has:

${\mathrm{\&gamma;}}_{S,D}^m={\left|h_{\mathrm{SD}}^m\right|}^2/{\mathrm{\&sigma;}}_k^2,$ ${\mathrm{\&gamma;}}_{S,R}^m={\left|h_{\mathrm{SR}}^m\right|}^2/{\mathrm{\&sigma;}}_r^2$ And ${\mathrm{\&gamma;}}_{R,D}^n={\left|h_{\mathrm{RD}}^n\right|}^2/{\mathrm{\&sigma;}}_k^2;$

Step 4: realize the renewal of code book through each code word in the code book is more newly arrived, be updated to corresponding to k code word of new code book

:

$c_k^{j+1}=\arg \underset{c\&Element;T}{\max }{E}_{h\&Element;Q_k}\left(R\left(c\right|h)\right),k=\mathrm{1,2},...,B;$

This step realizes through following calculating:

$\arg \underset{c\&Element;T}{\max }{E}_{h\&Element;Q_k}\left(R\left(c\right|h)\right)=\arg \underset{c\&Element;T}{\max }{E}_{h\&Element;Q_k}\left(\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{t}_{m,n}\frac{1}{2}{\log }_2(1+P^{m,n}{\mathrm{\&gamma;}}^{m,n})\right);$

Step 5: the definition error distance function is a distortion function:

And calculate the overall distortion degree of new code book

with this;

Step 6: observe algorithm and whether restrain; And if

stops iteration; Export optimum code book code word; Otherwise jump to step 2 until algorithmic statement, wherein ε is a preset minimum numeral.

4. the system combined resource allocation methods of the OFDM-AF based on Limited Feedback as claimed in claim 3 is characterized in that, the renewal of code word is embodied in optimizes following mixed integer programming problem:

$\underset{\{P,t\}}{\max }\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}\frac{1}{2}{t}_{m,n}{\log }_2(1+P_S^m{\mathrm{\&gamma;}}_{\mathrm{SD}}^m+\frac{P_S^m{P}_R^n{\mathrm{\&gamma;}}_{\mathrm{SR}}^m{\mathrm{\&gamma;}}_{\mathrm{RD}}^n}{P_S^m{\mathrm{\&gamma;}}_{\mathrm{SR}}^m+P_R^n{\mathrm{\&gamma;}}_{\mathrm{RD}}^n}),$

$s.t.\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{t}_{m,n}{P}_{m,n}\&le;P_t,P_{m,n}\&GreaterEqual;0,$

$\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}{t}_{m,n}=1,\&ForAll;n,\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{t}_{m,n}=1,\&ForAll;m,$

$t_{m,n}\&Element;\left\{\mathrm{0,1}\right\},\&ForAll;m,n,$

And through integer restriction serialization and dualization method acquisition optimal solution.

5. the system combined resource allocation methods of the OFDM-AF based on Limited Feedback as claimed in claim 4 is characterized in that, the dualization method becomes the optimization dual objective function with above-mentioned mixed integer programming problem:

$g(\mathrm{\&alpha;},\mathrm{\&beta;})=\underset{\{P,t\}}{\max }L(P,t,\mathrm{\&alpha;},\mathrm{\&beta;}),$

And dual problem:

$\underset{\{\mathrm{\&alpha;},\mathrm{\&beta;}\}}{\min }g(\mathrm{\&alpha;},\mathrm{\&beta;}),s.t.\mathrm{\&alpha;}\&GreaterEqual;0,\mathrm{\&beta;}\&GreaterEqual;0,$

α wherein, β is a dual variable, and Lagrangian L (α β) is configured to for P, t:

$L(P,t,\mathrm{\&alpha;},\mathrm{\&beta;})=\frac{1}{2}\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{t}_{m,n}{\log }_2(1+P_S^m{\mathrm{\&gamma;}}_{\mathrm{SD}}^m+\frac{P_S^m{P}_R^n{\mathrm{\&gamma;}}_{\mathrm{SR}}^m{\mathrm{\&gamma;}}_{\mathrm{RD}}^n}{P_S^m{\mathrm{\&gamma;}}_{\mathrm{SR}}^m+P_R^n{\mathrm{\&gamma;}}_{\mathrm{RD}}^n}).$

$+\mathrm{\&alpha;}(P_t-\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{P}_{m,n})+\underset{m=1}{\overset{N}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_m(1-\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{t}_{m,n})$

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