CN105591725A - Improved decoding forwarding relay communication system resource distribution method - Google Patents

Abstract

The invention discloses an improved decoding forwarding relay communication system resource distribution method, comprising: first establishing an improved decoding forwarding relay communication system resource distribution model; determining whether the transmission mode of each subcarrier pair is direct transmission or relay transmission, and determining the forwarding relay set corresponding to each subcarrier pair having a transmission mode of relay transmission; obtaining a power optimal solution through establishing the lagrangean function of the improved decoding forwarding relay communication system resource distribution model; calculating the transmission rate contribution value corresponding to each subcarrier pair according to the power optimal solution; and finally determining subcarrier pairs according to the transmission rate contribution value corresponding to all subcarrier pairs by utilizing a Hungary algorithm. The method fully utilizes the silence period and null sub-carriers of a second time slot base station, and adaptively adjusts subcarrier pair coupling and relay selection, thereby maximizing a frequency spectrum utilization rate, and maximizing the system capacity under fixed total power.

Description

A kind of modified decode-and-forward relay resource assignment method of communication system

Technical field

The present invention relates to a kind of telecommunication system resources distribution technique, especially relate to a kind of modified decode-and-forward relay logicalCommunication system resource allocation methods.

Background technology

OFDM (orthogonalfrequencydivisionmultiplexing, OFDM) technology hasHigh, the anti-fading ability of the availability of frequency spectrum is strong, resource is distributed flexibly and transfer rate advantages of higher, has become current and has moved futureThe key technology of moving communication. Meanwhile, relaying technique is as the key technology of LTE-A, and its height that can ensure communication system coversThe service quality of rate and Cell Edge User. In the relay communications system based on OFDM, allocation of research resources problem mainly relates toAnd relay selection, subcarrier distribution and power division, reasonably resource allocation algorithm can improve telecommunication system resources effectivelyUtilization ratio. Therefore, the relay communications system resource allocation problem based on OFDM has obtained paying close attention to widely.

The pass-through mode of relaying mainly contains amplification forwarding (AF), decoding forwards (DF), coding cooperative (CC) etc., at present forThe resource allocation problem of decode-and-forward relay communication system has had research widely. At TDD (TimeDivisionDuplexing, time division duplex) under pattern, adopt different subcarriers for former and later two time slots in same telex network processTransmission realizes subcarrier marriage problem, can effectively improve spectrum efficiency. For this problem, research and propose and demonstrate,proveBright by the link channel gain sequence to base station-via node, via node-destination node respectively, by identical rank sequence numberSubcarrier to match be optimum pairing scheme. But this optimum pairing is to be limited under the situation of the link that do not direct transfer, communication process only could be realized under relay forwarding, and in reality, a lot of situations are really not so. At traditional relaying(ConventionalRelay), in resource allocation problem research, in the second time slot relay forwarding process, base station keeps mourning in silence,Do not continue transmission information. In order to improve the availability of frequency spectrum, someone has proposed modified relaying (ImprovedRelay) communicationConcept, the idle sub-carrier that the second time slot base station can be utilized do not taken by relaying continues transmission information. For modified solutionCode forward relay model of communication system, someone has proposed some corresponding resource allocation methods, but these resource allocation methodsSelecting when forward relay, in transmitting procedure of some resource allocation methods same subcarrier pair only select one optimum inThe forwarding information that continued, space diversity gain is lower; Some resource allocation methods are not considered the difference of front and back time slot channelProperty, once in two processes of transmission, all select identical subcarrier transmission information, this makes the availability of frequency spectrum lower.

Summary of the invention

Technical problem to be solved by this invention is to provide a kind of modified decode-and-forward relay telecommunication system resources and distributesMethod, it can make communication system obtain higher taking the maximum capacity under communication system general power restrictive condition as targetPower system capacity.

The present invention solves the problems of the technologies described above adopted technical scheme: a kind of modified decode-and-forward relay communication systemSystem resource allocation methods, is characterized in that comprising the following steps:

1. the general power of supposing modified decode-and-forward relay communication system is PdBm, and relaying number is K, sub-carrier numberIt is that subchannel number is N that order is N, and N sub-channels has identical bandwidth and experiences separately independently frequency selectivityRayleigh fading, wherein, P > 0, K >=1, N > 1;

And require modified decode-and-forward relay communication system to be operated under TDD mode, the first time slot: base station toRelaying and object user broadcast singal; The second time slot: relaying sends to object by the signal receiving by decoding retransmission protocolUser, base station utilizes the subcarrier not taken by relaying to object user transmitted signal simultaneously;

In modified decode-and-forward relay communication system, object user adopts high specific merging mode to receive signal;

2. the resource allocator model of setting up modified decode-and-forward relay communication system, is described as: $\max \underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}\frac{{\mathrm{\ρ}}_{(i,j)}}{2}\{{\mathrm{\φ}}_{(i,j)}{\log }_2(1+{\mathrm{\α}}_{(i,j)}^R{p}_{(i,j)}^R)+(1-{\mathrm{\φ}}_{(i,j)})\[{\log }_2(1+{\mathrm{\γ}}_i^{SD,1})+{\log }_2(1+{\mathrm{\γ}}_j^{SD,2})\]\}$ , and this resource allocator model meets following constraintCondition: $\begin{array}{cc}A2:{\mathrm{\ρ}}_{(i,j)}\∈\{0,1\},{\mathrm{\φ}}_{(i,j)}\∈\{0,1\},\∀i,j;& A3:\underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}{\mathrm{\ρ}}_{(i,j)}\[p_i^{S,1}+{\mathrm{\φ}}_{(i,j)}{p}_{(i,j)}^R+(1-{\mathrm{\φ}}_{(i,j)})p_j^{S,2}\]\≤P;\end{array}$ $A4:p_i^{S,1}\≥0,p_{(i,j)}^R\≥0,p_j^{S,2}\≥0;$

Wherein, max () is for getting max function, 1≤i≤N, and 1≤j≤N, 1≤k≤K, k represents relaying sequence number, Φ_(i,j)Represent the forward relay set while forwarding on information on the subcarrier i in the first time slot subcarrier j in the second time slot,ρ_(i,j)And φ_(i,j)Value be 0 or 1, ρ_(i,j)Subcarrier i in=0 expression the first time slot and the subcarrier j in the second time slotUnpaired, ρ_(i,j)=1 represents the subcarrier i in the first time slot and the pairing of the subcarrier j in the second time slot, φ_(i,j)=0 representsSubcarrier pair (i, j) is passed through directly to object user transmission information, φ in base station_(i,j)=1 represents that subcarrier pair (i, j) passes through relayingTransmission information, subcarrier pair (i, j) is the combination being made up of subcarrier i and subcarrier j,Son while representing relay transmissionThe equivalent channel gain of carrier wave to (i, j) respective links,Symbol " || " is for getting absolutelyTo value symbol,Represent that base station is to relayingThe channel coefficients of link on subcarrier i,For arriving base stationΦ_(i,j)In channel coefficients on subcarrier i of the link of each relaying in the sequence number of relaying corresponding to minimum channel coefficient,Represent relaying k to object user's link the channel coefficients on subcarrier j,Represent the link of base station to object userChannel coefficients on subcarrier i,Represent transmitted power total when relaying transmits by subcarrier pair (i, j),Transmitted power while representing the first time slot base station broadcast singal on subcarrier i,Represent φ_(i,j)Transmission merit when the second time slot was by relaying k transmission in=1 o'clock on subcarrier jRate,Represent φ_(i,j)While direct transferring, receive the first time slot object user the letter that transmit by subcarrier i base station at=0 o'clockNumber signal to noise ratio,Represent base station to object user's link the additivity Gauss's white noise on subcarrier iAcoustical power,Represent φ_(i,j)The base station receiving the second time slot object user while direct transferring for=0 o'clock passes by subcarrier jThe signal to noise ratio of defeated signal,Represent φ_(i,j)While within=0 o'clock, direct transferring on the subcarrier j of the second time slotTransmitted power,Represent base station to object user's link the channel coefficients on subcarrier j,Represent that base station is to object useThe additive white Gaussian noise power of the link at family on subcarrier j; Constraints A1 represents a subcarrier energy and can only be withIndividual subcarrier pairing, constraints A2 represents ρ_(i,j)And φ_(i,j)Value can only be 0 or 1, constraints A3 represents modifiedThe general power restriction of decode-and-forward relay communication system, constraints A4 representsWithIt can only be positive number or 0;

3. determine the transmission means of each subcarrier pair:

For subcarrier pair (i, j), the deterministic process of its transmission means is: whenTime, determine sonCarrier wave is relay transmission to the transmission means of (i, j); WhenOrTime, determine the biography of subcarrier pair (i, j)Defeated mode is directly transmission, wherein, $\begin{array}{ccc}{\mathrm{\α}}_{i,k}^{SR}=\frac{|h_{i,k}^{SR}{|}^2}{{\mathrm{\σ}}_{i,k}^{SR}},& {\mathrm{\α}}_i^{SD}=\frac{|h_i^{SD}{|}^2}{{\mathrm{\σ}}_i^{SD}},& {\mathrm{\α}}_j^{RD}={\left({\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}\frac{\left|h_{j,k}^{RD}\right|}{{\mathrm{\σ}}_{j,k}^{RD}}\right)}^2,\end{array}$ Symbol " || " is for getting absolutelyTo value symbol,Represent base station to the link of relaying k the channel coefficients on subcarrier i,Represent the chain of base station to relaying kThe additive white Gaussian noise power of road on subcarrier i,Represent link the adding on subcarrier j of relaying k to object userProperty white Gaussian noise power;

4. determine the corresponding forward relay set of each subcarrier pair that transmission means is relay transmission:

For subcarrier pair (i, j), suppose that its transmission means is relay transmission, by its corresponding forward relay setForward relay set Φ while forwarding on the subcarrier j of information on subcarrier i in the first time slot in the second time slot_(i,j)ReallyBe decided to beWherein,Represent to get to makeValueRelaying when maximum is set expression symbol at this symbol " { } ";

5. _ 1, set up the Lagrangian of the resource allocator model of modified decode-and-forward relay communication system $L({\mathrm{\ρ}}_{(i,j)},{\mathrm{\φ}}_{(i,j)},p_{(i,j)}^R,p_j^{S,2},p_i^{S,1},\mathrm{\λ})=R-\mathrm{\λ}(\underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}{\mathrm{\ρ}}_{(i,j)}\[{\mathrm{\φ}}_{(i,j)}{p}_{(i,j)}^R+(1-{\mathrm{\φ}}_{(i,j)})(p_j^{S,2}+p_i^{S,1})\]-P),$ Wherein, λ represents Lagrange multiplier, $R=\frac{{\mathrm{\ρ}}_{(i,j)}}{2}\{{\mathrm{\φ}}_{(i,j)}{\log }_2(1+{\mathrm{\α}}_{(i,j)}^R{p}_{(i,j)}^R)+(1-{\mathrm{\φ}}_{(i,j)})\[{\log }_2(1+{\mathrm{\γ}}_i^{SD,1})+{\log }_2(1+{\mathrm{\γ}}_j^{SD,2})\]\};$

5. _ 2, set up dual objective function g (λ),G (λ) meets below approximatelyBundle condition: $\begin{array}{cc}A1:\underset{i=1}{\overset{N}{\Σ}}{\mathrm{\ρ}}_{(i,j)}=1,\underset{j=1}{\overset{N}{\Σ}}{\mathrm{\ρ}}_{(i,j)}=1,\∀i,j,& A2:{\mathrm{\ρ}}_{(i,j)}\∈\{0,1\},{\mathrm{\φ}}_{(i,j)}\∈\{0,1\},\∀i,j,\end{array}$ Wherein, max () is for getting max function;

5. _ 3, dual problem corresponding to g (λ) is described as: ming (λ), ming (λ) meets following constraints: λ >=0,Wherein, min () is for getting minimum value function;

5. _ 4, solve ming (λ), obtainWithOptimization solution, correspondence is designated asWith $\begin{array}{cc}{\tilde{p}}_i^{S,1}=\max \left({\mathrm{\ρ}}_{(i,j)}\right(1-{\mathrm{\φ}}_{(i,j)})\[\frac{1}{2\mathrm{\λ}}-\frac{1}{{\mathrm{\α}}_i^{SD}}\],0),& {\tilde{p}}_{(i,j)}^R=\max ({\mathrm{\ρ}}_{(i,j)}{\mathrm{\φ}}_{(i,j)}\[\frac{1}{2\mathrm{\λ}}-\frac{1}{{\mathrm{\α}}_{(i,j)}^R}\],0),\end{array}$ ${\tilde{p}}_j^{S,2}=max\left({\mathrm{\ρ}}_{(i,j)}\right(1-{\mathrm{\φ}}_{(i,j)})\[\frac{1}{2\mathrm{\λ}}-\frac{1}{{\mathrm{\α}}_j^{SD}}\],0),$ Wherein, ${\mathrm{\α}}_j^{SD}=\frac{|h_j^{SD}{|}^2}{{\mathrm{\σ}}_j^{SD}},$ Symbol " || " is the symbol that takes absolute value,Represent base station to object user's link the letter on subcarrier jRoad coefficient,Represent base station to object user's link the additive white Gaussian noise power on subcarrier j;

5. _ 5, calculate the corresponding transfer rate contribution margin of each subcarrier pair, by corresponding subcarrier pair (i, j) transmission speedRate contribution margin is designated as L_(i,j)，

5. _ 6,, by the matrix of a corresponding all subcarrier pairs transfer rate contribution margin composition N × N dimension, be designated as L,Wherein, L_(1,1)Represent the corresponding transfer rate contribution margin of subcarrier pair (1,1), L_(1,N)Represent sonCarrier wave is to (1, N) corresponding transfer rate contribution margin, L_(N,1)Represent the corresponding transfer rate contribution margin of subcarrier pair (N, 1),L_(N,N)Represent the corresponding transfer rate contribution margin of subcarrier pair (N, N);

5. _ 7, calculate and make by Hungary AlgorithmMeeting constraintsTime ρ_(i,j)Value, wherein, max () is for getting max function, L_(i,j)That is to say in LCoordinate position is the value of the element of (i, j);

6. calculate φ_(i,j)Transmitted power when the second time slot was by relaying k transmission in=1 o'clock on subcarrier jExcellentDissolve, be designated as ${\tilde{p}}_j^{k,2},{\tilde{p}}_j^{k,2}=\frac{|h_{j,k}^{RD}{|}^2({\tilde{p}}_{(i,j)}^R-{\tilde{p}}_i^{S,1})}{{\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}\left(\right|h_{j,k}^{RD}{|}^2/{\mathrm{\σ}}_{j,k}^{RD})},$ Wherein, k ∈ Φ_(i,j)。

The λ of described step in 5. obtains by iterative search, and detailed process is: a1, make q represent iterations, and make that q's is initialValue is 1; Lagrange multiplier after a2, the q time iteration of calculating, is designated as λ^q， ${\mathrm{\λ}}^q={\mathrm{\λ}}^{q-1}-\mathrm{\β}\{P-\underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}{\mathrm{\ρ}}_{(i,j)}\[{\mathrm{\φ}}_{(i,j)}{\tilde{p}}_{(i,j)}^R+(1-{\mathrm{\φ}}_{(i,j)})({\tilde{p}}_i^{S,1}+{\tilde{p}}_j^{S,2})\]\},$ Wherein, as q=1 λ in season^q-1＝λ₀，λ₀For given initial value, λ in the time of q ≠ 1^q-1Represent the Lagrange after the q-1 time iterationMultiplier, β represents iteration step length; A3, work as λ^q>=0 and $0\≤P-\underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}{\mathrm{\ρ}}_{(i,j)}\[{\mathrm{\φ}}_{(i,j)}{\tilde{p}}_{(i,j)}^R+(1-{\mathrm{\φ}}_{(i,j)})({\tilde{p}}_i^{S,1}+{\tilde{p}}_j^{S,2})\]\≤\mathrm{\ϵ}$ While meeting, stop iteration, and make λ=λ^q; Work as λ^q>=0 and $0\≤P-\underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}{\mathrm{\ρ}}_{(i,j)}\[{\mathrm{\φ}}_{(i,j)}{\tilde{p}}_{(i,j)}^R+(1-{\mathrm{\φ}}_{(i,j)})({\tilde{p}}_i^{S,1}+{\tilde{p}}_j^{S,2})\]\≤\mathrm{\ϵ}$ While not meeting, make q=q+1, then return to step a2 and continue to carry out; Wherein, λ=λ^qBe assignment symbol with "=" in q=q+1Number, ε is a very little positive number.

In described step 5.-2Wherein, min () is for getting minimum value function.

In described step 5.-2

ε=10 in described step 5.-3^-6P。

Compared with prior art, the invention has the advantages that:

1) the inventive method is in modified decode-and-forward relay communication system, realized simultaneously subcarrier pairing with how inThe forwarding that continues, not only takes full advantage of silence period and the idle sub-carrier of the second time slot base station, and can be according to channel differenceSelf adaptation is adjusted subcarrier pairing and relay selection, and this can maximize the availability of frequency spectrum of system, has improved space simultaneously and has dividedDiversity gain, under the certain condition of system general power, maximizes power system capacity.

2) the inventive method is solving in subcarrier pairing and many relay forwardings problem, the equivalence while obtaining many relay forwardingsChannel gain and multiple forward relay set, two time slot links while making relay transmission are equivalent to the link transmission that direct transfers, therebyThe complexity that has reduced problem, is easier to Project Realization.

Brief description of the drawings

Fig. 1 is the overall realization flow block diagram of the inventive method;

Fig. 2 is that the power system capacity of resource allocation algorithm of the inventive method and existing three kinds of models is with the general power of systemSimulation curve when size variation;

Fig. 3 is that the power system capacity of resource allocation algorithm of the inventive method and existing three kinds of models is with relaying number sizeSimulation curve when variation;

Fig. 4 is that the power system capacity of the resource allocation algorithm of the inventive method and existing three kinds of models becomes with number of sub carrier waveSimulation curve when change.

Detailed description of the invention

Below in conjunction with accompanying drawing, embodiment is described in further detail the present invention.

In order further to improve the availability of frequency spectrum, the present invention, in modified decode-and-forward relay communication system, proposes oneKind realizing in subcarrier pairing situation, same subcarrier pair can be selected multiple relay forwarding information in each transmitting procedureResource allocation methods, thus take full advantage of otherness and the spatial domain free degree of channel, improve diversity gain and total system and heldAmount.

A kind of modified decode-and-forward relay resource assignment method of communication system that the present invention proposes, its overall realization flowAs shown in Figure 1, it comprises the following steps block diagram:

1. the general power of supposing modified decode-and-forward relay communication system is PdBm, and relaying number is K, sub-carrier numberIt is that subchannel number is N that order is N, and N sub-channels has identical bandwidth and experiences separately independently frequency selectivityRayleigh fading, wherein, P > 0, K >=1, N > 1.

And require modified decode-and-forward relay communication system to be operated under time division duplex (TDD) pattern, the first time slot: baseStand to relaying and object user broadcast singal; The second time slot: relaying forwards (DF) agreement by the signal receiving by decoding and sends outDeliver to object user, base station can utilize the subcarrier not taken by relaying to object user transmitted signal simultaneously.

In modified decode-and-forward relay communication system, object user adopts existing high specific merging mode to receive letterNumber.

2. the resource allocator model of setting up modified decode-and-forward relay communication system, is described as: $\max \underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}\frac{{\mathrm{\ρ}}_{(i,j)}}{2}\{{\mathrm{\φ}}_{(i,j)}{\log }_2(1+{\mathrm{\α}}_{(i,j)}^R{p}_{(i,j)}^R)+(1-{\mathrm{\φ}}_{(i,j)})\[{\log }_2(1+{\mathrm{\γ}}_i^{SD,1})+{\log }_2(1+{\mathrm{\γ}}_i^{SD,2})\]\}$ , and this resource allocator model meets below approximatelyBundle condition: $\begin{array}{cc}A2:{\mathrm{\ρ}}_{(i,j)}\∈\{0,1\},{\mathrm{\φ}}_{(i,j)}\∈\{0,1\},\∀i,j;& A3:\underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}{\mathrm{\ρ}}_{(i,j)}\[p_i^{S,1}+{\mathrm{\φ}}_{(i,j)}{p}_{(i,j)}^R+(1-{\mathrm{\φ}}_{(i,j)})p_j^{S,2}\]\≤P;\end{array}$ $A4:p_i^{S,1}\≥0,p_{(i,j)}^R\≥0,p_j^{S,2}\≥0.$

Wherein, max () is for getting max function, 1≤i≤N, and 1≤j≤N, 1≤k≤K, k represents relaying sequence number, Φ_(i,j)Represent the forward relay set while forwarding on information on the subcarrier i in the first time slot subcarrier j in the second time slot,ρ_(i,j)And φ_(i,j)Value be 0 or 1, ρ_(i,j)Subcarrier i in=0 expression the first time slot and the subcarrier j in the second time slotUnpaired, ρ_(i,j)=1 represents the subcarrier i in the first time slot and the pairing of the subcarrier j in the second time slot, φ_(i,j)=0 representsSubcarrier pair (i, j) is passed through directly to object user transmission information, φ in base station_(i,j)=1 represents that subcarrier pair (i, j) passes through relayingTransmission information, subcarrier pair (i, j) is the combination being made up of subcarrier i and subcarrier j,Son while representing relay transmissionThe equivalent channel gain of carrier wave to (i, j) respective links, can be expressed asSymbol " || " be the symbol that takes absolute value,Represent that base station is to relayingThe channel coefficients of link on subcarrier i,ForBase station is to Φ_(i,j)In channel coefficients on subcarrier i of the link of each relaying in relaying corresponding to minimum channel coefficientSequence number,Represent relaying k to object user's link the channel coefficients on subcarrier j,Represent that base station is to object useThe channel coefficients of the link at family on subcarrier i,Represent transmission merit total when relaying transmits by subcarrier pair (i, j)Rate,Transmitted power while representing the first time slot base station broadcast singal on subcarrier i,Represent φ_(i,j)Transmission merit when the second time slot was by relaying k transmission in=1 o'clock on subcarrier jRate,Represent φ_(i,j)Transmit by subcarrier i the base station receiving the first time slot object user while direct transferring for=0 o'clockThe signal to noise ratio of signal,Represent base station to object user's link the additivity white Gaussian on subcarrier iNoise power,Represent φ_(i,j)The base station receiving the second time slot object user while direct transferring for=0 o'clock is by subcarrier jThe signal to noise ratio of the signal of transmission,Represent φ_(i,j)The subcarrier j of the second time slot while direct transferring for=0 o'clockOn transmitted power,Represent base station to object user's link the channel coefficients on subcarrier j,Represent that base station is to orderAdditive white Gaussian noise power on subcarrier j of user's link; Constraints A1 represents a subcarrier energy and can onlyWith the pairing of subcarrier (same subcarrier also can), constraints A2 represents ρ_(i,j)And φ_(i,j)Value can only be 0Or 1, constraints A3 represents the general power restriction of modified decode-and-forward relay communication system, constraints A4 representsWithIt can only be positive number or 0.

3. determine the transmission means of each subcarrier pair:

For subcarrier pair (i, j), the deterministic process of its transmission means is: whenAndTime, determine sonCarrier wave is relay transmission to the transmission means of (i, j); WhenOrTime, determine the transmission of subcarrier pair (i, j)Mode is directly transmission, wherein, $\begin{array}{ccc}{\mathrm{\α}}_{i,k}^{SR}=\frac{|h_{i,k}^{SR}{|}^2}{{\mathrm{\σ}}_{i,k}^{SR}},& {\mathrm{\α}}_i^{SD}=\frac{|h_i^{SD}{|}^2}{{\mathrm{\σ}}_i^{SD}},& {\mathrm{\α}}_j^{RD}={\left({\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}\frac{\left|h_{j,k}^{RD}\right|}{{\mathrm{\σ}}_{j,k}^{RD}}\right)}^2,\end{array}$ Symbol " || " is for getting definitelyValue symbol,Represent base station to the link of relaying k the channel coefficients on subcarrier i,Represent the link of base station to relaying kAdditive white Gaussian noise power on subcarrier i,Represent relaying k to object user's link the additivity on subcarrier jWhite Gaussian noise power.

4. determine the corresponding forward relay set of each subcarrier pair that transmission means is relay transmission:

For subcarrier pair (i, j), suppose that its transmission means is relay transmission, by its corresponding forward relay setForward relay set Φ while forwarding on the subcarrier j of information on subcarrier i in the first time slot in the second time slot_(i,j)ReallyBe decided to beWherein,Represent to get to makeValueRelaying when maximum is set expression symbol at this symbol " { } ".

At this, supposeThe increasing function about k,Corresponding to Φ_(i,j)InMinimum relaying, so,In relaying all can be correctly decoded the signal that base station sends over, and optimum'sSelection makes equivalent channel gainMaximum relaying,

5. _ 1, set up the Lagrangian of the resource allocator model of modified decode-and-forward relay communication system $L({\mathrm{\ρ}}_{(i,j)},{\mathrm{\φ}}_{(i,j)},p_{(i,j)}^R,p_j^{S,2},p_i^{S,1},\mathrm{\λ})=R-\mathrm{\λ}(\underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}{\mathrm{\ρ}}_{(i,j)}\[{\mathrm{\φ}}_{(i,j)}{p}_{(i,j)}^R+(1-{\mathrm{\φ}}_{(i,j)})(p_j^{S,2}+p_i^{S,1})\]-P),$ Wherein, λ represents Lagrange multiplier, $R=\frac{{\mathrm{\ρ}}_{(i,j)}}{2}\{{\mathrm{\φ}}_{(i,j)}{\log }_2(1+{\mathrm{\α}}_{(i,j)}^R{p}_{(i,j)}^R)+(1-{\mathrm{\φ}}_{(i,j)})\[{\log }_2(1+{\mathrm{\γ}}_i^{SD,1})+{\log }_2(1+{\mathrm{\γ}}_j^{SD,2})\]\}.$

5. _ 2, set up dual objective function g (λ),G (λ) meets below approximatelyBundle condition: $\begin{array}{cc}A1:\underset{i=1}{\overset{N}{\Σ}}{\mathrm{\ρ}}_{(i,j)}=1,\underset{j=1}{\overset{N}{\Σ}}{\mathrm{\ρ}}_{(i,j)}=1,\∀i,j,& A2:{\mathrm{\ρ}}_{(i,j)}\∈\{0,1\},{\mathrm{\φ}}_{(i,j)}\∈\{0,1\},\∀i,j,\end{array}$ Wherein, max () is for getting max function.

5. _ 3, dual problem corresponding to g (λ) is described as: ming (λ), ming (λ) meets following constraints: λ >=0,Wherein, min () is for getting minimum value function.

5. _ 4, solve ming (λ), obtainWithOptimization solution, correspondence is designated asWith $\begin{array}{cc}{\tilde{p}}_i^{S,1}=\max \left({\mathrm{\ρ}}_{(i,j)}\right(1-{\mathrm{\φ}}_{(i,j)})\[\frac{1}{2\mathrm{\λ}}-\frac{1}{{\mathrm{\α}}_i^{SD}}\],0),& {\tilde{p}}_{(i,j)}^R=\max ({\mathrm{\ρ}}_{(i,j)}{\mathrm{\φ}}_{(i,j)}\[\frac{1}{2\mathrm{\λ}}-\frac{1}{{\mathrm{\α}}_{(i,j)}^R}\],0),\end{array}$ ${\tilde{p}}_j^{S,2}=max\left({\mathrm{\ρ}}_{(i,j)}\right(1-{\mathrm{\φ}}_{(i,j)})\[\frac{1}{2\mathrm{\λ}}-\frac{1}{{\mathrm{\α}}_j^{SD}}\],0),$ Wherein, ${\mathrm{\α}}_j^{SD}=\frac{|h_j^{SD}{|}^2}{{\mathrm{\σ}}_j^{SD}},$ Symbol " || " is the symbol that takes absolute value,Represent base station to object user's link the letter on subcarrier jRoad coefficient,Represent base station to object user's link the additive white Gaussian noise power on subcarrier j.

5. _ 5, calculate the corresponding transfer rate contribution margin of each subcarrier pair, by corresponding subcarrier pair (i, j) transmission speedRate contribution margin is designated as L_(i,j)，

5. _ 6,, by the matrix of a corresponding all subcarrier pairs transfer rate contribution margin composition N × N dimension, be designated as L,Wherein, L_(1,1)Represent the corresponding transfer rate contribution margin of subcarrier pair (1,1), L_(1,N)Represent sonCarrier wave is to (1, N) corresponding transfer rate contribution margin, L_(N,1)Represent the corresponding transfer rate contribution margin of subcarrier pair (N, 1),L_(N,N)Represent the corresponding transfer rate contribution margin of subcarrier pair (N, N).

5. _ 7, calculate and make by Hungary AlgorithmMeeting constraintsTime ρ_(i,j)Value, wherein, max () is for getting max function, L_(i,j)That is to say in L and sitMark is set to the value of the element of (i, j).

In this specific embodiment, the λ of step in 5. obtains by iterative search, and detailed process is: a1, make q represent repeatedlyGeneration number, and to make the initial value of q be 1; Lagrange multiplier after a2, the q time iteration of calculating, is designated as λ^q， ${\mathrm{\λ}}^q={\mathrm{\λ}}^{q-1}-\mathrm{\β}\{P-\underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}{\mathrm{\ρ}}_{(i,j)}\[{\mathrm{\φ}}_{(i,j)}{\tilde{p}}_{(i,j)}^R+(1-{\mathrm{\φ}}_{(i,j)})({\tilde{p}}_i^{S,1}+{\tilde{p}}_j^{S,2})\]\},$ Wherein, as q=1 λ in season^q-1＝λ₀，λ₀For example, for the initial value of setting,Min () is for getting minimum value function, λ in the time of q ≠ 1^q-1RepresentLagrange multiplier after the q-1 time iteration, β represents iteration step length,A3, work as λ^q>=0 and $0\≤P-\underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}{\mathrm{\ρ}}_{(i,j)}\[{\mathrm{\φ}}_{(i,j)}{\tilde{p}}_{(i,j)}^R+(1-{\mathrm{\φ}}_{(i,j)})({\tilde{p}}_i^{S,1}+{\tilde{p}}_j^{S,2})\]\≤\mathrm{\ϵ}$ While meeting, stop iteration, and make λ=λ^q; Work as λ^q>=0 and $0\≤P-\underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}{\mathrm{\ρ}}_{(i,j)}\[{\mathrm{\φ}}_{(i,j)}{\tilde{p}}_{(i,j)}^R+(1-{\mathrm{\φ}}_{(i,j)})({\tilde{p}}_i^{S,1}+{\tilde{p}}_j^{S,2})\]\≤\mathrm{\ϵ}$ While not meeting, make q=q+1, then returnStep a2 continues to carry out; Wherein, λ=λ^qBe assignment with "=" in q=q+1, ε is a very little positive number, as gets ε＝10^-6P。

6. calculate φ_(i,j)Transmitted power when the second time slot was by relaying k transmission in=1 o'clock on subcarrier jOptimizationSeparate, be designated as ${\tilde{p}}_j^{k,2},{\tilde{p}}_j^{k,2}=\frac{|h_{j,k}^{RD}{|}^2({\tilde{p}}_{(i,j)}^R-{\tilde{p}}_i^{S,1})}{{\Σ}_{k\∈{\mathrm{\Φ}}_{(i,j)}}\left(\right|h_{j,k}^{RD}{|}^2/{\mathrm{\σ}}_{j,k}^{RD})},$ Wherein, k ∈ Φ_(i,j)。

Below by Computer Simulation, to further illustrate feasibility and the superiority of the inventive method.

When emulation, channel adopts six footpath rayleigh fading channels, and Monte Carlo simulation number of times is 1000 times. For the ease of comparing,The resource allocation algorithm of existing three kinds of models has been carried out to emulation simultaneously. In emulation legend, IDFw/oSP representative does not haveThe algorithm that carries out the many relay-models of modified (Improved) of subcarrier pairing, ConventionalDF represents traditional DFThe algorithm of many relay forwardings model, SingleRelay represents single relay forwarding model resource allocation algorithm, Proposed representativeThe inventive method.

Total with system of the power system capacity of resource allocation algorithm that Fig. 2 has provided the inventive method and existing three kinds of modelsSimulation curve when watt level changes. Wherein, in this emulation, get number of sub carrier wave N=16, relaying number K=4, and hypothesisThe additive white Gaussian noise power of all links is 1dBm. As can be seen from Figure 2, along with the increase of the general power P of system, everyThe increased power of individual sub-allocation of carriers, also can correspondingly increase power system capacity. Wherein, SingleRelay method is because of its pointDiversity gain minimum, therefore power system capacity is minimum; IDFw/oSP method and the inventive method have all adopted modified trunking traffic,Improved the availability of frequency spectrum, therefore power system capacity is all higher than ConventionalDF method, and the inventive method is owing to utilizing letterRoad difference has realized again subcarrier pairing, therefore can obtain the highest power system capacity.

Fig. 3 has provided the power system capacity of resource allocation algorithm of the inventive method and existing three kinds of models with relaying numberSimulation curve when size variation. Wherein, in this emulation, get number of sub carrier wave N=16, the general power P=10dBm of system, andThe additive white Gaussian noise power of supposing all links is 1dBm. As can be seen from Figure 3, along with the increase of relaying number, skyThe territory free degree increases, and can be used for the also corresponding increase of relaying number of repeating base station information in system, thereby space diversity is increasedBenefit increases, the corresponding lifting of power system capacity, and also the inventive method is with respect to the resource allocation algorithm of existing three kinds of models all the timeThere is preferably performance.

Fig. 4 has provided the power system capacity of resource allocation algorithm of the inventive method and existing three kinds of models with sub-carrier numberSimulation curve when order changes. Wherein, in this emulation, get relaying number K=4, the general power P=10dBm of system, and hypothesisThe additive white Gaussian noise power of all links is 1dBm. As can be seen from Figure 4, along with sub-carrier number object increases, frequencyDiversity gain increases, and the free degree of subcarrier pairing simultaneously increases, the corresponding lifting of power system capacity, and the inventive method is at sub-carrier numberOrder can obtain the power system capacity higher than the resource allocation algorithm of existing three kinds of models while variation.

Claims (5)

1. a modified decode-and-forward relay resource assignment method of communication system, is characterized in that comprising the following steps:

1. the general power of supposing modified decode-and-forward relay communication system is PdBm, and relaying number is K, and number of sub carrier wave isN is that subchannel number is N, and N sub-channels has identical bandwidth and experiences separately independently frequency selectivity RayleighDecline, wherein, P > 0, K >=1, N > 1;

And require modified decode-and-forward relay communication system to be operated under TDD mode, the first time slot: base station is to relayingAnd object user broadcast singal; The second time slot: relaying sends to object user by the signal receiving by decoding retransmission protocol,Base station utilizes the subcarrier not taken by relaying to object user transmitted signal simultaneously;

In modified decode-and-forward relay communication system, object user adopts high specific merging mode to receive signal;

2. the resource allocator model of setting up modified decode-and-forward relay communication system, is described as: $\max \underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{\left(i,j\right)}}\frac{{\mathrm{\ρ}}_{\left(i,j\right)}}{2}\left\{{\mathrm{\φ}}_{\left(i,j\right)}{\log }_2\left(1+{\mathrm{\α}}_{\left(i,j\right)}^R{p}_{\left(i,j\right)}^R\right)+\left(1-{\mathrm{\φ}}_{\left(i,j\right)}\right)\[{\log }_2\left(1+{\mathrm{\γ}}_i^{SD,1}\right)+{\log }_2\left(1+{\mathrm{\γ}}_j^{SD,2}\right)\]\right\}$ $,$ And this resource is dividedJoin model and meet following constraints: $A3:\underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{\left(i,j\right)}}{\mathrm{\ρ}}_{\left(i,j\right)}\[p_i^{S,1}+{\mathrm{\φ}}_{\left(i,j\right)}{p}_{\left(i,j\right)}^R+\left(1-{\mathrm{\φ}}_{\left(i,j\right)}\right)p_j^{S,2}\]\≤P;$ $A4:p_i^{S,1}\≥0,p_{(i,j)}^R\≥0,p_j^{S,2}\≥0;$

Wherein, max () is for getting max function, 1≤i≤N, and 1≤j≤N, 1≤k≤K, k represents relaying sequence number, Φ_(i,j)RepresentForward relay set while forwarding on the subcarrier j of information on subcarrier i in the first time slot in the second time slot, ρ_(i,j)Withφ_(i,j)Value be 0 or 1, ρ_(i,j)Subcarrier i in=0 expression the first time slot and the subcarrier j in the second time slot are unpaired,ρ_(i,j)=1 represents the subcarrier i in the first time slot and the pairing of the subcarrier j in the second time slot, φ_(i,j)=0 expression base station is passed throughSubcarrier pair (i, j) is directly to object user transmission information, φ_(i,j)=1 expression subcarrier pair (i, j) is believed by relay transmissionBreath, subcarrier pair (i, j) is the combination being made up of subcarrier i and subcarrier j,Subcarrier pair while representing relay transmissionThe equivalent channel gain of (i, j) respective links,Symbol " || " is the symbol that takes absolute valueNumber,Represent that base station is to relayingThe channel coefficients of link on subcarrier i, For base station is to Φ_(i,j)InThe sequence number of the relaying that minimum channel coefficient in the channel coefficients of the link of each relaying on subcarrier i is corresponding,Show relayingK is the channel coefficients on subcarrier j to object user's link,Represent base station to object user's link on subcarrier iChannel coefficients,Represent transmitted power total when relaying transmits by subcarrier pair (i, j), TableTransmitted power while showing the first time slot base station broadcast singal on subcarrier i, Represent φ_(i,j)＝1Time the second time slot by the transmitted power on relaying k when transmission subcarrier j,Represent φ_(i,j)While within=0 o'clock, direct transferringOne time slot object user receives the signal to noise ratio of the signal transmitting by subcarrier i base station, Represent baseThe additive white Gaussian noise power of the object of standing user's link on subcarrier i,Represent φ_(i,j)=0 o'clock when direct transferringThe signal to noise ratio of the signal that transmit by subcarrier j the base station receiving the second time slot object user, Represent φ_(i,j)The transmitted power while direct transferring for=0 o'clock on the subcarrier j of the second time slot,Represent the chain of base station to object userThe channel coefficients of road on subcarrier j,Represent base station to object user's link the additivity Gauss's white noise on subcarrier jAcoustical power; Constraints A1 represent a subcarrier energy and can only with the pairing of subcarrier, constraints A2 represents ρ_(i,j)Withφ_(i,j)Value can only be 0 or 1, constraints A3 represents the general power restriction of modified decode-and-forward relay communication system, approximatelyBundle condition A4 representsWithIt can only be positive number or 0;

3. determine the transmission means of each subcarrier pair:

For subcarrier pair (i, j), the deterministic process of its transmission means is: whenAndTime, determine subcarrierBe relay transmission to the transmission means of (i, j); WhenOrTime, determine the transmission side of subcarrier pair (i, j)Formula is directly transmission, wherein, ${\mathrm{\α}}_{i,k}^{SR}=\frac{|h_{i,k}^{SR}{|}^2}{{\mathrm{\σ}}_{i,k}^{SR}},{\mathrm{\α}}_i^{SD}=\frac{|h_i^{SD}{|}^2}{{\mathrm{\σ}}_i^{SD}},{\mathrm{\α}}_j^{RD}={\left({\mathrm{\Σ}}_{k\∈{\mathrm{\Φ}}_{(i,j)}}\frac{\left|h_{j,k}^{RD}\right|}{{\mathrm{\σ}}_{j,k}^{RD}}\right)}^2,$ Symbol " || " is for taking absolute valueSymbol,Represent base station to the link of relaying k the channel coefficients on subcarrier i,Represent that base station exists to the link of relaying kAdditive white Gaussian noise power on subcarrier i,The additivity on subcarrier j is high to object user's link to represent relaying kThis white noise power;

4. determine the corresponding forward relay set of each subcarrier pair that transmission means is relay transmission:

For subcarrier pair (i, j), suppose that its transmission means is relay transmission, be first by its corresponding forward relay setForward relay set Φ while forwarding on the subcarrier j of information on subcarrier i in time slot in the second time slot_(i,j)Be defined asWherein, Represent to get to makeValue when maximumRelaying, be set expression symbol at this symbol " { } ";

5. _ 1, set up the Lagrangian of the resource allocator model of modified decode-and-forward relay communication system $L({\mathrm{\ρ}}_{(i,j)},{\mathrm{\φ}}_{\left(i,j\right)},p_{\left(i,j\right)}^R,p_j^{S,2},p_i^{S,1},\mathrm{\λ}),$ Wherein, λ represents Lagrange multiplier, $R=\frac{{\mathrm{\ρ}}_{\left(i,j\right)}}{2}\left\{{\mathrm{\φ}}_{\left(i,j\right)}{\log }_2\left(1+{\mathrm{\α}}_{\left(i,j\right)}^R{p}_{\left(i,j\right)}^R\right)+\left(1-{\mathrm{\φ}}_{\left(i,j\right)}\right)\[{\log }_2\left(1+{\mathrm{\γ}}_i^{SD,1}\right)+{\log }_2\left(1+{\mathrm{\γ}}_j^{SD,2}\right)\]\right\};$

5. _ 2, set up dual objective function g (λ),G (λ) meets following constraint barPart: Wherein, max () is for getting max function;

5. _ 3, dual problem corresponding to g (λ) is described as: ming (λ), ming (λ) meets following constraints: λ >=0, itsIn, min () is for getting minimum value function;

5. _ 4, solve ming (λ), obtainWithOptimization solution, correspondence is designated asWith ${\tilde{p}}_i^{S,1}=max\left({\mathrm{\ρ}}_{(i,j)}\right(1-{\mathrm{\φ}}_{(i,j)})\[\frac{1}{2\mathrm{\λ}}-\frac{1}{{\mathrm{\α}}_i^{SD}}\],0),$ ${\tilde{p}}_{\left(i,j\right)}^R=max({\mathrm{\ρ}}_{(i,j)}{\mathrm{\φ}}_{(i,j)}\[\frac{1}{2\mathrm{\λ}}-\frac{1}{{\mathrm{\α}}_{\left(i,j\right)}^R}\],0),$ Wherein,Symbol " || " is the symbol that takes absolute value,RepresentBase station is the channel coefficients on subcarrier j to object user's link,Represent that the link that arrives object user in base station is at subcarrierAdditive white Gaussian noise power on j;

5. _ 5, calculate the corresponding transfer rate contribution margin of each subcarrier pair, by corresponding subcarrier pair (i, j) transfer rate tributeThe value of offering is designated as L_(i,j)，

5. _ 6,, by the matrix of a corresponding all subcarrier pairs transfer rate contribution margin composition N × N dimension, be designated as L,Wherein, L_(1,1)Represent the corresponding transfer rate contribution margin of subcarrier pair (1,1), L_(1,N)Represent sonCarrier wave is to (1, N) corresponding transfer rate contribution margin, L_(N,1)Represent the corresponding transfer rate contribution margin of subcarrier pair (N, 1),L_(N,N)Represent the corresponding transfer rate contribution margin of subcarrier pair (N, N);

5. _ 7, calculate and make by Hungary AlgorithmMeeting constraints Time ρ_(i,j)Value, wherein, max () is for getting max function, L_(i,j)That is to say the element that in L, coordinate position is (i, j)Value;

6. calculate φ_(i,j)Transmitted power when the second time slot was by relaying k transmission in=1 o'clock on subcarrier jOptimization solution,Be designated as ${\tilde{p}}_j^{k,2},{\tilde{p}}_j^{k,2}=\frac{|h_{j,k}^{RD}{|}^2\left({\tilde{p}}_{\left(i,j\right)}^R-{\tilde{p}}_i^{S,1}\right)}{{\Σ}_{k\∈{\mathrm{\Φ}}_{\left(i,j\right)}}\left(|h_{j,k}^{RD}{|}^2/{\mathrm{\σ}}_{j,k}^{RD}\right)},$ Wherein, k ∈ Φ_(i,j)。

2. a kind of modified decode-and-forward relay resource assignment method of communication system according to claim 1, is characterized in thatThe λ of described step in 5. obtains by iterative search, and detailed process is: a1, make q represent iterations, and to make the initial value of q be 1;Lagrange multiplier after a2, the q time iteration of calculating, is designated as λ^q， ${\mathrm{\λ}}^q={\mathrm{\λ}}^{q-1}-\mathrm{\β}\left\{P-\underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{\left(i,j\right)}}{\mathrm{\ρ}}_{\left(i,j\right)}\[{\mathrm{\φ}}_{\left(i,j\right)}{\tilde{p}}_{\left(i,j\right)}^R+\left(1-{\mathrm{\φ}}_{\left(i,j\right)}\right)\left({\tilde{p}}_i^{S,1}+{\tilde{p}}_j^{S,2}\right)\]\right\},$ Wherein, as q=1 λ in season^q-1＝λ₀，λ₀For given initial value, λ in the time of q ≠ 1^q-1Represent the Lagrange after the q-1 time iterationMultiplier, β represents iteration step length; A3, work as λ^q>=0 and $0\≤P-\underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{\left(i,j\right)}}{\mathrm{\ρ}}_{\left(i,j\right)}\[{\mathrm{\φ}}_{\left(i,j\right)}{\tilde{p}}_{\left(i,j\right)}^R+\left(1-{\mathrm{\φ}}_{\left(i,j\right)}\right)\left({\tilde{p}}_i^{S,1}+{\tilde{p}}_j^{S,2}\right)\]\≤\mathrm{\ϵ}$ While meeting, stop iteration, and make λ=λ^q; Work as λ^q>=0 and $0\≤P-\underset{i=1}{\overset{N}{\Σ}}\underset{j=1}{\overset{N}{\Σ}}{\Σ}_{k\∈{\mathrm{\Φ}}_{\left(i,j\right)}}{\mathrm{\ρ}}_{\left(i,j\right)}\[{\mathrm{\φ}}_{\left(i,j\right)}{\tilde{p}}_{\left(i,j\right)}^R+\left(1-{\mathrm{\φ}}_{\left(i,j\right)}\right)\left({\tilde{p}}_i^{S,1}+{\tilde{p}}_j^{S,2}\right)\]\≤\mathrm{\ϵ}$ While not meeting, make q=q+1, then return to step a2 and continue to carry out; Wherein, λ=λ^qBe assignment symbol with "=" in q=q+1Number, ε is a very little positive number.

3. a kind of modified decode-and-forward relay resource assignment method of communication system according to claim 2, its feature existsIn described step 5.-2Wherein, min () is for getting minimum value function.

4. a kind of modified decode-and-forward relay resource assignment method of communication system according to claim 2, its feature existsIn described step 5.-2

5. a kind of modified decode-and-forward relay resource assignment method of communication system according to claim 2, its feature existsε=10 in described step 5.-3^-6P。