CN103249155B - A kind of resource allocation methods of OFDM wireless relay network system - Google Patents

Abstract

The present invention discloses the resource allocation methods of a kind of OFDM wireless relay network system and system thereof, and this system comprises base station, relaying and user, and the method comprises the following steps: its user's set of serving determined by (1) each relaying; (2) external iteration Counter Value is defined, the original allocation value of subcarrier and user label; (3) internal layer iteration count initial value is defined, initialization Lagrangian; (4) calculate each base-station transmission data to relaying and each relay transmission data to the power division of each subcarrier of user, obtain current hop power system capacity; (5) judge whether to reach internal layer iteration optimum, if reach, enter external iteration, enter (6), otherwise recalculate internal layer iteration count value and upgrade Lagrangian, get back to (4); (6) judge whether to reach external iteration optimum, if reach, termination of iterations obtains optimal value, otherwise recalculates external iteration Counter Value and upgrade the apportioning cost of subcarrier, gets back to (3).

Description

A kind of resource allocation methods of OFDM wireless relay network system

Technical field

The present invention relates to a kind of OFDM wireless relay network system and resource allocation methods thereof.

Background technology

Resourse Distribute is the important component part of OFDM wireless relay network.In wireless relay network, relaying is in half-duplex state, and the complete transmission of a packet is divided into base station to relaying and is relayed to two periods of user, and these two periods can take the different time.And user needs to select suitable relaying to provide relay services for it, and suitable subcarrier to be selected to transmit data and to need for sub-carrier configuration power.If Resourse Distribute is unreasonable, not only can reduce network capacity, also can have influence on the service quality of user.

In prior art, generally realize Resourse Distribute by feasible zone search method.In the feasible zone that this algorithm defines in each constraints, step-length and the ascent direction of each iteration are set according to first-order condition, finally reach effect of optimization.When variable is less, feasible zone search method has very high efficiency.But OFDM junction network also exists the problem of a large amount of sub carries allocation, if use existing feasible zone search method, directly in higher dimensional space, seek optimal solution, its time complexity will be very high.If at this moment use intelligent optimization algorithm by the problem of complexity settling time, but its performance is but often stable not.

Summary of the invention

Goal of the invention: the present invention discloses a kind of OFDM wireless relay network system and resource allocation methods thereof, the method can realize the distribution of Internet resources with lower Time & Space Complexity, realize the heap(ed) capacity of system, and algorithm performance is stablized.

Technical scheme: a kind of OFDM wireless relay network system, it is characterized in that, this system comprises: base station, relaying and user.Base station is used for transmission and the reception of wireless signal; Relaying is used for transmitting between base station and user the intermediary of data, for the copying of signal, sends, adjusts and gain amplifier; User is used for the reception of wireless signal.

In order to promote the capacity of whole relay system, and reduce the complexity of algorithm and ensure the stability of algorithm, a kind of distribution method of OFDM wireless relay network resource, is characterized in that, comprise the following steps:

(1) based on the sub-carrier channels gain estimated value of relay transmission data to User window, its user's set of serving is determined according to first regular each relaying;

(2) external iteration counter initial value is defined, according to user's set, the original allocation value of each relaying stochastic generation subcarrier, and obtain the user label of subcarrier, enter internal layer iteration;

(3) optimal value is obtained through internal layer iteration, enter external iteration, according to the 6th rule, judge whether to reach outer optimal value, reach then iteration ends, obtain relay system heap(ed) capacity, optimum sub carries allocation and optimum sub-carrier power to distribute, otherwise enter step (4);

(4) recalculate external iteration Counter Value, according to the 7th Policy Updates sub carries allocation value, rebound (2) enters internal layer iteration.

As preferably, the external iteration in step (3) is in order to the distribution for optimizing subcarrier, and the internal layer iteration in step (2) is in order to the distribution for optimizing sub-carrier power;

As preferably, the first rule in step (1) is:

$R_m{=}_n^{\arg }\max \{{\Σ}_{k=1}^n\left|h_{n,m,k}\right|,n=1,2,\mathrm{...},N\},$

Wherein R _mrepresent the individual user-selected relaying numbering of m; represent each sub-carrier channels gain mould when user m selects relaying n and value.

As preferably, the internal layer iteration in described step (2) comprises the following steps:

1. the initial value of internal layer iteration count is set, initialization Lagrangian;

2. according to Second Rule, calculate the power assignment value of relay transmission data to each subcarrier of User window, then according to three sigma rule, obtain the power assignment value of base-station transmission data to each subcarrier of relaying period, thus obtain the capacity of current hop system;

3. for the capacity of relay system, according to the 4th rule, judge whether relay system reaches optimum value, reach then internal layer iteration ends; Otherwise enter step 4.;

4. recalculate the value of internal layer iteration count, according to the 5th rule, upgrade Lagrangian, get back to step 2..

As preferably, the internal layer iterative step in described step (2) 2. in Second Rule be:

$P_{r,k}=\{{\[\frac{1}{2W}\frac{{\left|h_{s,n,k}\right|}^2}{\mathrm{\λ}{\left|h_{n,m_k,k}\right|}^2+{\Σ}_{n=1}^N{\mathrm{\μ}}_n{\left|h_{s,n,k}\right|}^2}-\frac{N_{0}W}{{\left|h_{n,m_k,k}\right|}^2}\]}^{+},k=1,2,\mathrm{...},N\},$

Wherein P _r,krepresent the power assignment value that a kth subcarrier obtains to User window in relay transmission data; λ and μ _mrepresent Lagrangian; h _{s, n, k}with respectively represent subcarrier base-station transmission data to when relaying and relay transmission data to the user m of relaying n when user _kchannel gain.

As preferably, the internal layer iterative step in described step (2) 2. in three sigma rule be:

$P_{s,k}=\{{\mathrm{\Σ}}_{m=1}^M\frac{{\left|h_{n,m,k}\right|}^2}{{\left|h_{s,n,k}\right|}^2}{w}_{m,k}{P}_{r,k},k=1,2,\mathrm{...},K\},$

Wherein P _s,krepresent the power assignment value that a kth subcarrier obtains to User window in relay transmission data; w _m,krepresent the sub-carrier selection factor, work as w _m,kwhen=1, subcarrier k distributes to user m, works as w _m,kwhen=0, subcarrier k distributes to other users except user m.

As preferably, the internal layer iterative step in described step (2) 3. in the 4th rule be:

|C(t ₂)-C(t ₂-1)|/C(t ₂)≤1％，

Wherein C (t ₂) represent the power system capacity that current internal layer iteration obtains; C (t ₂-1) power system capacity that last internal layer iteration obtains is represented.

As preferably, the internal layer iterative step in described step (2) 4. in the 5th rule be:

$\mathrm{\λ}(t_2+1)={\[\mathrm{\λ}\left(t_2\right)-\frac{1}{5}(P_s-\underset{k=1}{\overset{K}{\Σ}}\frac{{\left|h_{n,m_k,k}\right|}^2}{{\left|h_{s,n,k}\right|}^2}{P}_{r,k})\mathrm{\λ}\left(t_2\right)\]}^{+}$

${\mathrm{\μ}}_n(t_2+1)={\[{\mathrm{\μ}}_n\left(t_2\right)-\frac{1}{5}(P_n-{\Σ}_{k=1}^K{P}_{r,k}){\mathrm{\μ}}_n\left(t_2\right)\]}^{+},n=1,2,\mathrm{...}N$

Wherein λ (t ₂), μ _n(t ₂) represent current Lagrangian; λ (t ₂+ 1), μ _m(t ₂+ 1) Lagrangian after upgrading is represented; P _srepresent the maximum transmission power of transmitting terminal; P _nrepresent the maximum transmission power of relaying n.

As preferably, the 6th rule in described step (3) is:

|C(t ₁)-C(t ₁-1)|/C(t ₁)≤1％，

Wherein C (t ₁) represent the power system capacity that current external iteration obtains; C (t ₁-1) power system capacity that last external iteration obtains is represented.

As preferably, the 7th rule in described step (4) is:

$m_k{=}_m^{\arg }\max \{{\left|h_{n,m,k}\right|}^2{P}_{r,k},n\∈\{1,2,\mathrm{...},N\},m\∈U_m|,\},$

$w_{m,k}=\left\{\begin{array}{c}1,m=m_k\\ 0,m\≠m_k\end{array}\right.$

Wherein m _krepresent that subcarrier k distributes to the Customs Assigned Number of user.

Beneficial effect: the present invention is by providing a kind of distribution method of new OFDM wireless relay network resource, for the high time complexity occurred in existing algorithm and low stability, by twice iterative algorithm, achieve the distribution realizing Internet resources with lower Time & Space Complexity, realize the heap(ed) capacity of system, and algorithm performance is stablized.

Accompanying drawing explanation

The flow chart of the OFDM wireless relay network Resourse Distribute that Fig. 1 designs for the present invention.

Fig. 2 is the hypothesis scene graph of base station and relaying.

Fig. 3 is that the Performance Ratio of OFDM relay system Resource Allocation in Networks algorithm is according to figure.

Fig. 4 is the iterations frequency figure of two-layer iterative algorithm.

Embodiment

Below in conjunction with Fig. 1, the present invention is further described.

A kind of OFDM wireless relay network, it is K that system comprises number of subcarriers, and the number of users of service is M, and relaying quantity is N, and the bandwidth that each subcarrier takies is W.

A distribution method for OFDM wireless relay network resource, is characterized in that, comprise the following steps:

(1) channel estimation module of base station and each relaying was the first period to base-station transmission data to period of relaying, and the channel gain estimated value of each subcarrier of the first period is h _{s, n, k}, relay transmission data were the second period to the period of each user, and the channel gain estimated value of each subcarrier of the second period is h _{n, m, k}.Based on the sub-carrier channels gain estimated value of the second period, according to the first rule, each relaying determines that the user that it is served gathers U ₁, U ₂..., U _n.First rule is

$R_m{=}_n^{\arg }\max \{{\Σ}_{k=1}^n\left|h_{n,m,k}\right|,n=1,2,\mathrm{...},N\},$

Wherein R _mrepresent the individual user-selected relaying numbering of m; represent each sub-carrier channels gain mould when user m selects relaying n and value.

(2) external iteration counter initial value t is defined ₁=0, according to U ₁, U ₂..., U _n, the original allocation w of each relaying cooperation stochastic generation subcarrier _m,k(t ₁), obtain the user label m using subcarrier k _k(t ₁).Enter internal layer iteration, step is:

1. internal layer iteration count initial value t is defined ₂=0, initialization Lagrangian λ (t ₂)=1, μ (t ₂)=(1,1 ... 1).

2. according to Second Rule, the power division P of each subcarrier is calculated _r,k(t ₂).Second Rule is:

$P_{r,k}=\{{\[\frac{1}{2W}\frac{{\left|h_{s,n,k}\right|}^2}{\mathrm{\λ}{\left|h_{n,m_k,k}\right|}^2+{\Σ}_{n=1}^N{\mathrm{\μ}}_n{\left|h_{s,n,k}\right|}^2}-\frac{N_{0}W}{\left|h_{n,m_k,k}\right|}\]}^{+},k=1,2,\mathrm{...},N\},$

Wherein P _r,krepresent the power assignment value that a kth subcarrier obtains to User window in relay transmission data; λ and μ _nrepresent Lagrangian; h _{s, n, k}with respectively represent subcarrier base-station transmission data to when relaying and relay transmission data to the user m of relaying n when user _kchannel gain.The power division P of first each subcarrier of period is obtained again according to three sigma rule _s,k(t ₂) thus obtain the capacity of current hop system.Three sigma rule is:

$P_{s,k}=\{{\mathrm{\Σ}}_{m=1}^M\frac{{\left|h_{n,m,k}\right|}^2}{{\left|h_{s,n,k}\right|}^2}{w}_{m,k}{P}_{r,k},k=1,2,\mathrm{...},K\},$

Wherein P _s,krepresent the power assignment value that a kth subcarrier obtains to User window in relay transmission data; w _m,krepresent the sub-carrier selection factor, work as w _m,kwhen=1, subcarrier k distributes to user m, works as w _m,kwhen=0, subcarrier k distributes to other users except user m.Capacity formula is

$C_2\left(t_2\right)=\frac{w}{2}\underset{m=1}{\overset{M}{\Σ}}\underset{k=1}{\overset{K}{\Σ}}{\log }_2(1+\frac{min\{{\left|h_{s,n,k}\right|}^2{P}_{s,k}\left(t_2\right),{\left|h_{n,m,k}\right|}^2{P}_{r,k}\left(t_2\right)\}}{N_{0}W})$

Wherein C (t ₂) be the capacity of relay system.

3. for C (t ₂), the optimum of internal layer iteration whether is reached according to the 4th rule judgment relay system capacity.If reach, internal layer iteration ends, enters external iteration, namely enters step (3); Otherwise enter step 4..4th rule is:

|C ₂(t ₂)-C ₂(t ₂-1)|/C(t ₂)≤1％，

Wherein C ₂(t ₂) represent the power system capacity that current internal layer iteration obtains; C ₂(t ₂-1) power system capacity that last internal layer iteration obtains is represented.

4. internal layer iteration count t ₂=t ₂+ 1.According to the 5th Policy Updates Lagrangian λ (t ₂), μ (t ₂).Rebound step 2..5th rule is:

$\mathrm{\λ}(t_2+1)={\[\mathrm{\λ}\left(t_2\right)-\frac{1}{5}(P_s-\underset{k=1}{\overset{K}{\Σ}}\frac{{\left|h_{n,m_k,k}\right|}^2}{{\left|h_{s,n,k}\right|}^2}{P}_{r,k})\mathrm{\λ}\left(t_2\right)\]}^{+}$

${\mathrm{\μ}}_n(t_2+1)={\[{\mathrm{\μ}}_n\left(t_2\right)-\frac{1}{5}(P_n-{\mathrm{\Σ}}_{k=1}^K{P}_{r,k}){\mathrm{\μ}}_n\left(t_2\right)\]}^{+},n=1,2,...N$

Wherein λ (t ₂), μ _n(t ₂) represent current Lagrangian; λ (t ₂+ 1), μ _n(t ₂+ 1) Lagrangian after upgrading is represented; P _srepresent the maximum transmission power of transmitting terminal; Pn represents the maximum transmission power of relaying n.

(3) C is made ₁(t ₁)=C ₂(t ₂), whether reach outer optimum according to the 6th rule judgment relay system capacity, if meet the 6th rule, then expression meets outer optimum, then global iterative stops, C ₁(t ₁) be the heap(ed) capacity of relay system, w _m,k(t ₁) be optimum sub carries allocation, P _s,k(t ₂), P _r,k(t ₂) distribute for optimum sub-carrier power; Otherwise enter step (4).6th rule is:

|C ₁(t ₁)-C ₁(t ₁-1)|/C ₁(t ₁)≤1％，

Wherein C (t ₁) represent the power system capacity that current external iteration obtains; C (t ₁-1) power system capacity that last external iteration obtains is represented.

(4) external iteration counter t ₁=t ₁+ 1, according to the apportioning cost w of the 7th Policy Updates subcarrier _m,k(t ₁), the 1. portion of in rebound step (2), carries out inner iterative again.7th rule is:

$m_k{=}_m^{\arg }\max \{{\left|h_{n,m,k}\right|}^2{P}_{r,k},n\∈\{1,2,\mathrm{...},N\},m\∈U_m|,\},$

$w_{m,k}=\left\{\begin{array}{c}1,m=m_k\\ 0,m\≠m_k\end{array}\right.$

Wherein m _krepresent that subcarrier k distributes to the Customs Assigned Number of user.

Be described below in conjunction with embodiment, as shown in Figure 2, construct a wireless relay network.Be provided with 1 base station, 3 relayings, 10 users in network, the quantity of subcarrier is 64, and the frequency bandwidth that each subcarrier takies is 1MHz.The maximum transmission power of setting base station is 1W.The maximum transmission power of three relayings is identical, is all 0.5W.Channel is multi-path Fading Channel, and each footpath fading factor is [0-8.69-17.37-26.06-34.74-43.43] dB, and channel distribution is independent identically distributed white Gaussian noise.If base station, relaying and user are in two-dimensional space, the coordinate of base station 1 is (0,0), the coordinate of the first relaying 2 is (0,1), the coordinate of the second relaying 3 is (cos (-π/6), sin (-π/6)), the seat (cos (-5 π/6), sin (-5 π/6)) of the 3rd relaying 3.If the maximal cover radius of community is 2.5, user coordinates position is being uniformly distributed in cell coverage area.Each channel is also subject to path loss, if square being inversely proportional to of the channel yield value of receiving terminal time domain and transmitting-receiving two-end distance.Stochastic generation rayleigh distributed, can obtain every footpath domain channel gain of each channel according to path loss, then through the channel gain of FFT (fast fourier transform) to each each subcarrier of link.Two-layer alternative manner described in Fig. 1 carries out Resourse Distribute, obtains the heap(ed) capacity of relay system.

As shown in Figure 3, the Performance comparision curve based on the situation supposed in Fig. 2 algorithm of two-layer generation and genetic algorithm and greedy algorithm is given.Can find out, after adopting two-layer iterative algorithm to realize optimal resource allocation, its power system capacity has obvious lifting relative to other two algorithms.Relative Hereditary algorithm, the performance boost amplitude of two-layer iterative algorithm is more than 50%, and relative greedy algorithm, improve especially more than one times.When SNR (signal to noise ratio) is higher, the performance boost that two-layer iterative algorithm brings will be more obvious.

The complexity of algorithm and stability are also the key factors of measure algorithm quality, the expression formula providing time complexity is theoretically difficult to for two-layer iterative algorithm, so under having added up different channels parameter, the optimum results of 1000 algorithms, have recorded ground floor iterations and the second layer iterations of each algorithm realization, its result is as shown in Figure 4, the first time expectation of iterations is lower, be approximately 7, and iterations is less than the probability of 10 more than 90%, iterations concentrates on 4 ~ 8 times; The expectation of second time iterations is higher, and be approximately 26, iterations concentrates on 20 ~ 30 times.According to the statistics of each iteration total degree, total iterations is generally no more than 200 times, and because algorithm itself only employs some simple calculations formula, the complexity of its computing is also not high, and iterations is also more concentrated, so the stability of algorithm is better.

In sum, the invention provides a kind of distribution method of OFDM wireless relay network resource, the method is obvious compared with the method improving performance of prior art, and has the feature of low complex degree and high stability.

Claims (2)

1. a resource allocation methods for OFDM wireless relay network system, is applied to wireless relay network system, and this OFDM wireless relay network system comprises base station, relaying and user;

Base station is used for transmission and the reception of wireless signal; Relaying is used for transmitting between base station and user the intermediary of data, for the copying of signal, sends, adjusts and gain amplifier; User is used for the reception of wireless signal

It is characterized in that, the method is used for the Resourse Distribute of wireless relay network, and it comprises the following steps:

(1) based on the sub-carrier channels gain estimated value of relay transmission data to User window, according to the first rule, its user's set of serving determined by each relaying;

First rule is:

$R_m{=}_n^{\arg }\max \{{\Σ}_{k=1}^n\left|h_{n,m,k}\right|,n=1,2,\mathrm{...},N\},$

Wherein R _mrepresent the individual user-selected relaying numbering of m; represent each sub-carrier channels gain mould when user m selects relaying n and value; N is intrasystem relaying total number;

(2) external iteration counter initial value is defined, according to user's set, the original allocation value of each relaying stochastic generation subcarrier, and obtain the user label of subcarrier, enter internal layer iteration; Its internal layer iteration comprises the following steps:

1. the initial value of internal layer iteration count is set, initialization Lagrangian;

2. according to Second Rule, the power assignment value of relay transmission data to each subcarrier of User window is calculated;

Second Rule is:

$P_{r,k}=\{{\[\frac{1}{2W}\frac{{\left|h_{s,n,k}\right|}^2}{\mathrm{\λ}{\left|h_{n,m_k,k}\right|}^2+{\Σ}_{n=1}^N{\mathrm{\μ}}_n{\left|h_{s,n,k}\right|}^2}-\frac{N_{0}W}{{\left|h_{n,m_k,k}\right|}^2}\]}^{+},k=1,2,\mathrm{...},N\}$

Wherein P _r,krepresent the power assignment value that a kth subcarrier obtains to User window in relay transmission data; λ and μ _nrepresent Lagrangian; h _{s, n, k}with respectively represent subcarrier base-station transmission data to when relaying and relay transmission data to the user m of relaying n when user _kchannel gain; N ₀for the one-sided power spectrum density of link white Gaussian noise; W is the bandwidth that each subcarrier takies;

Again according to three sigma rule, obtain the power assignment value of base-station transmission data to each subcarrier of relaying period, thus obtain the capacity of current hop system;

Three sigma rule is:

$P_{s,k}=\{{\mathrm{\Σ}}_{m=1}^M\frac{{\left|h_{n,m,k}\right|}^2}{{\left|h_{s,n,k}\right|}^2}{w}_{m,k}{P}_{r,k},k=1,2,\mathrm{...},K\}$

Wherein P _s,krepresent the power assignment value of base-station transmission data to a kth subcarrier of relaying period; w _m,krepresent the sub-carrier selection factor, work as w _m,kwhen=1, subcarrier k distributes to user m, works as w _m,kwhen=0, subcarrier k distributes to other users except user m; K is ofdm system total number of sub-carriers order;

3. for the capacity of relay system, according to the 4th rule, judge whether relay system reaches optimum value, reach then internal layer iteration ends; Otherwise enter step 4.;

4th rule is:

|C(t ₂)-C(t ₂-1)|/C(t ₂)≤1％

Wherein C (t ₂) represent the power system capacity that current internal layer iteration obtains; C (t ₂-1) power system capacity that last internal layer iteration obtains is represented;

4. recalculate the value of internal layer iteration count, according to the 5th rule, upgrade Lagrangian, get back to step 2.;

5th rule is:

$\mathrm{\λ}(t_2+1)={\[\mathrm{\λ}\left(t_2\right)-\frac{1}{5}(P_s-\underset{k=1}{\overset{K}{\Σ}}\frac{{\left|h_{n,m_k,k}\right|}^2}{{\left|h_{s,n,k}\right|}^2}{P}_{r,k})\mathrm{\λ}\left(t_2\right)\]}^{+}$

${\mathrm{\μ}}_n(t_2+1)={\[{\mathrm{\μ}}_n\left(t_2\right)-\frac{1}{5}(P_n-{\mathrm{\Σ}}_{R=1}^K{P}_{r,k}){\mathrm{\μ}}_n\left(t_2\right)\]}^{+},n=1,2,...N$

Wherein λ (t ₂), μ _n(t ₂) represent current Lagrangian; λ (t ₂+ 1), μ _n(t ₂+ 1) Lagrangian after upgrading is represented; P _srepresent the maximum transmission power of transmitting terminal; P _nrepresent the maximum transmission power of relaying n;

(3) optimal value is obtained through internal layer iteration, enter external iteration, according to the 6th rule, judge whether to reach outer optimal value, reach then iteration ends, obtain relay system heap(ed) capacity, optimum sub carries allocation and optimum sub-carrier power to distribute, otherwise enter step (4);

6th rule is:

|C(t ₁)-C(t ₁-1)|/C(t ₁)≤1％，

Wherein C (t ₁) represent the power system capacity that current external iteration obtains; C (t ₁-1) power system capacity that last external iteration obtains is represented;

(4) recalculate external iteration Counter Value, according to the 7th rule, upgrade sub carries allocation value, rebound (2) enters internal layer iteration;

7th rule is:

$m_k{=}_m^{\arg }\max \{{\left|h_{n,m,k}\right|}^2{P}_{r,k},n\∈\{1,2,\mathrm{...},N\},m\∈U_m|,\},$

$w_{mk}=\left\{\begin{array}{c}1,m=m_k\\ 0,m\≠m_k\end{array}\right.$

Wherein m _krepresent that subcarrier k distributes to the Customs Assigned Number of user; U _mit is user's set of m relay services.

2. the resource allocation methods of OFDM wireless relay network system as claimed in claim 1, it is characterized in that, external iteration is for optimizing the distribution of subcarrier, and internal layer iteration is for optimizing the distribution of sub-carrier power.