CN102752256A - Method and system for allocating multi-user cooperation orthogonal frequency division multiplexing (OFMD) system resources - Google Patents

Abstract

The invention discloses a method and a system for allocating multi-user cooperation orthogonal frequency division multiplexing (OFMD) system resources and relates to the technical field of cooperation communication. The method comprises the steps of determining a transmission mode of a subcarrier utilized when a source node sends information according to channel gain, wherein the transmission mode comprises a direct transmission mode and a cooperation mode; when the transmission mode of the subcarrier is the cooperation mode, determining the corresponding relay node and a rear-section subcarrier from the relay node to a target node; and according to the transmission mode of the subcarrier, the relay node and the rear-section subcarrier, utilizing a genetic algorithm to allocate bits with corresponding quantity to the subcarrier. Under the condition of certain power, the method and the system can remarkably improve throughput of the OFMD system and have wide application prospects.

Description

Multi-user collaborative ofdm system resource allocation methods and system

Technical field

The present invention relates to the communication for coordination technical field, particularly a kind of multi-user collaborative ofdm system resource allocation methods and system.

Background technology

At present, more and more rich data is professional, causes the mobile Internet development rapidly.Meanwhile, high-speed data has increased challenge for traditional cellular communication system.How to utilize existing base station and terminal,, satisfy each user's different service requirement, become a research focus through rational resource allocation.Because at LTE-Advanced (Long Term Evolution-Advanced)) increased collaborative relaying technique in the system, system can utilize space diversity to come to increase power system capacity with the power consumption of minimum.Van der Meulen etc. at first propose can improve the availability of frequency spectrum through communication for coordination, strengthen the reliability of wireless network.Laneman etc. have proposed cooperative modes such as fixed relay, selection relaying, and derived outage probability and power system capacity.

The core of communication for coordination is to utilize virtual-antenna to divide collection, increases power system capacity.Particularly be exactly spatially; Utilize the antenna of user's mobile phone terminal on every side; Form a VAA (Virtual Antenna Array, virtual antenna array), to the characteristic of channel; Source node is with when destination node is communicated by letter, also can a part of information distribution to those through repeated link can saving power subcarrier.Do not need many antennas just can reach higher speed through this method user.OFDM (Orthogonal Frequency Division Multiplexing, i.e. orthogonal frequency division multiplexi) communication for coordination at present is a standard perfect in IEEE802.16.

Ofdm system has a lot of subcarriers, and is quadrature between the subcarrier.Each subcarrier is the arrowband simultaneously, under deep fading's situation, on average on single narrow-band sub-carriers, can be approximated to be the flatness decline.Can allow the user according to self channel characteristic like this, adaptive chooser carrier wave is communicated by letter.For example, a number of sub-carrier is the deep fading to a user, might be to select preferably to other users.Therefore ofdm system can more make full use of limited frequency spectrum resources, and particularly in 3G and LTE, OFDM is a basic technology.

At present, also very not many to the research of the resource allocation in the communication for coordination.At paper Yidong Lang; Dirk

and Karl-Dirk Kammeyer; " Efficient Power Allocation for Outage Restricted Asymmetric Distributed MIMO Multi-hop Networks "; Personal; Indoor and Mobile Radio Communications; 2008 (PIMRC 2008), IEEE International Symposium on.pp.1-5 is among the doi:10.1109/PIMRC.2008.4699758; Analyzed the outage probability end to end in the distributed multihop symmetrical network, and under the certain situation of outage probability, made gross power minimum.But this paper is not considered the communication between source node and the destination node.Paper Bo Gui and Leonard J.Cimini; Jr. " Resource Allocation Algorithms for Multiuser Cooperative OFDMA Systems with Subchannel Permutation " Information Sciences and Systems; 2008.CIS S 2008.42nd Annual Conference on.19-21March 2008.pp.692-697, doi:

10.1109/CISS.2008.4558611 considered the communication between source node and the destination node, but the bit allocation algorithm that waits wherein can not cause the waste of power according to the channel gain adjustment method of salary distribution of each number of sub-carrier, has reduced throughput.

Summary of the invention

The technical problem that (one) will solve

The technical problem that the present invention will solve is: how a kind of multi-user collaborative ofdm system resource allocation methods and system are provided, under the certain situation of power, improve the throughput of ofdm system.

(2) technical scheme

For solving the problems of the technologies described above, the present invention provides a kind of multi-user collaborative ofdm system resource allocation methods, and it comprises step:

A: the transmission mode of confirming the subcarrier that source node is adopted when sending information according to channel gain; Said transmission mode comprises the pattern of direct transferring and collaborative pattern;

B:, confirm the corresponding relay node, and said via node is to the back segment subcarrier of destination node when the transmission mode of said subcarrier during for collaborative pattern;

C: according to the transmission mode of said subcarrier, and said via node and said back segment subcarrier, adopting genetic algorithm is the bit of said subcarrier allocation respective numbers.

Preferably, said steps A specifically comprises step:

A1: calculate the channel gain of current subcarrier i from source node to k via node

With the channel gain of current subcarrier i from k via node to destination node

In smaller value $\mathrm{Min}\{G_{{s,r}_k}\left(i\right),G_{r_k,d}\left(i\right)\};$

A2: judge the channel gain G of current subcarrier i from the source node to the destination node _{S, d}(i) whether less than said smaller value

If judge that the transmission mode of current subcarrier i is collaborative pattern; Otherwise, judge that the transmission mode of current subcarrier i is the pattern of direct transferring;

A3: repeat said steps A 1 to A2, all be determined until the transmission mode of all subcarriers.

Preferably, said step B specifically comprises step:

B1: the transmission mode of confirming in the said steps A is made the leading portion subcarrier for the subcarrier note of collaborative pattern;

B2:, from all said subcarriers, choose current subcarrier j successively for current leading portion subcarrier m; Wherein, the initial value of m is 1, and m≤M, and M representes the sum of said leading portion subcarrier; The initial value of j is 1, and j≤N, and N representes the sum of said subcarrier;

B3: for current subcarrier j, from all via nodes, choose current via node k successively, calculate corresponding equivalent channel gain then respectively; Wherein, the initial value of k is 1, and k≤K, and K representes the sum of said via node;

B4: for current leading portion subcarrier m; Find the combination of a number of sub-carrier and via node to make said equivalent channel gain obtain maximum; With the back segment subcarrier of the subcarrier in the said combination, with the via node of the via node in the said combination as current leading portion subcarrier m correspondence as current leading portion subcarrier m correspondence;

B5: repeat said step B2 ~ B4, all find corresponding back segment subcarrier and via node until all leading portion subcarriers.

Preferably, among the said step B3, the computing formula of said equivalent channel gain is following:

$G_{\mathrm{eq}}=\left(m\right)=\frac{G_{{s,r}_k}\left(m\right)G_{r_k,d}\left(j\right)}{G_{{s,r}_k}\left(m\right)+G_{r_k,d}\left(j\right)-G_{s,d}\left(m\right)};$

Wherein, G ^Eq(m) represent said equivalent channel gain; The channel gain of expression subcarrier m from source node to k via node;

The channel gain of expression subcarrier j from k via node to destination node; G _{S, d}(m) channel gain of expression subcarrier m from the source node to the destination node.

Preferably, said step C specifically comprises step:

C1: the initiation parameter that genetic algorithm is set; Said initiation parameter comprises: gross power, population number of individuals, generation gap parameter, fiducial value, crossover probability, variation probability, maximum iteration time; And individual chromosome number, and said chromosome number equals the sum of said subcarrier;

C2: create initial population as current population; Each individual chromosomal value is mapped as the quantity of the bit that each said subcarrier distributes in the said initial population, and said chromosomal value between 0 between the said fiducial value;

C3: according to the transmission mode of the definite said subcarrier of said steps A; And said via node and the said back segment subcarrier confirmed among the said step B; Under the restrictive condition of said gross power, calculate total speed of each individuals in the current population, as the desired value of current population;

C4: calculate the fitness of each individuals in the current population according to the desired value of current population, select the maximum individuality of fitness;

C5: judge whether iterations reaches said maximum iteration time, if, be the bit of said subcarrier allocation respective numbers according to chromosomal value in the individuality of fitness maximum, process ends; Otherwise, execution in step C6;

C6: the fitness according to each individuals in the current population, carry out selection operation to current population;

C7: carry out interlace operation according to the current population of said crossover probability after to selection operation;

C8: carry out mutation operation according to the current population of said variation probability after, obtain new population, carry out said step C3 to interlace operation.

The present invention also provides a kind of multi-user collaborative ofdm system resource allocation system, and said system comprises:

Pattern determining unit is used for confirming according to channel gain the transmission mode of the subcarrier that source node is adopted when sending information; Said transmission mode comprises the pattern of direct transferring and collaborative pattern;

Collaborative mode unit, the transmission mode that is used for when said subcarrier is when working in coordination with pattern, to confirm the corresponding relay node, and said via node is to the back segment subcarrier of destination node;

The Bit Allocation in Discrete unit is used for the transmission mode according to said subcarrier, and said via node and said back segment subcarrier, and adopting genetic algorithm is the bit of said subcarrier allocation respective numbers.

Preferably, said pattern determining unit comprises:

The smaller value module is used to calculate the channel gain of current subcarrier i from source node to k via node

With the channel gain of current subcarrier i from k via node to destination node

In smaller value $\mathrm{Min}\{G_{{s,r}_k}\left(i\right),G_{r_k,d}\left(i\right)\};$

The mode decision module is used for the channel gain G from the source node to the destination node at current subcarrier i _{S, d}(i) less than said smaller value

The time, judge that the transmission mode of subcarrier i is collaborative pattern; And, at the channel gain G of current subcarrier i from the source node to the destination node _{S, d}(i) more than or equal to said smaller value

The time, judge that the transmission mode of subcarrier i is the pattern of direct transferring.

Preferably, said Bit Allocation in Discrete unit comprises:

Initialization module; Be used to be provided with the initiation parameter of genetic algorithm; Said initiation parameter comprises: gross power, population number of individuals, generation gap parameter, fiducial value, crossover probability, variation probability, maximum iteration time; And individual chromosome number, and said chromosome number equals the sum of said subcarrier;

Initial population is created module, is used to create initial population, and offers the desired value computing module; Each individual chromosomal value is mapped as the quantity of the bit that each said subcarrier distributes in the said initial population, and said chromosomal value between 0 between the said fiducial value;

Said desired value computing module is used for the transmission mode according to said subcarrier, and said via node and said back segment subcarrier, under said gross power restrictive condition, calculates total speed of each individuals in the current population, as the desired value of current population;

The fitness computing module is used for calculating according to the desired value of current population the fitness of current each individuals of population, and selects the maximum individuality of fitness;

The Bit Allocation in Discrete module is used to write down iterations, and when iterations reaches said maximum iteration time, is the bit of said subcarrier allocation respective numbers according to chromosomal value in the individuality of fitness maximum;

Select module, be used for fitness, current population is carried out selection operation according to current each individuals of population;

Cross module is used for carrying out interlace operation according to the current population of said crossover probability after to selection operation;

The variation module is used for carrying out mutation operation according to the current population of said variation probability after to interlace operation, obtains new population, offers said desired value computing module.

(3) beneficial effect

Said multi-user collaborative ofdm system resource allocation methods of the present invention and system; At first confirm the transmission mode of each number of sub-carrier according to channel gain; And, adopt the bit number that genetic algorithm is carried each number of sub-carrier to carry out the non-equivalent distribution at last, under the certain situation of power to further definite via node of the subcarrier of collaborative transmission and back segment subcarrier; Can significantly improve the throughput of ofdm system, be with a wide range of applications.

Description of drawings

Fig. 1 is the cooperative communication model sketch map of the embodiment of the invention;

Fig. 2 is the said multi-user collaborative ofdm system of an embodiment of the invention resource allocation methods flow chart;

Fig. 3 is the modular structure sketch map of the said multi-user collaborative ofdm system of embodiment of the invention resource allocation system;

Fig. 4 is the throughput contrast sketch map of system of the present invention and legacy system.

Embodiment

Below in conjunction with accompanying drawing and embodiment, specific embodiments of the invention describes in further detail.Following examples are used to explain the present invention, but are not used for limiting scope of the present invention.

Fig. 1 is the cooperative communication model sketch map of the embodiment of the invention, and is as shown in Figure 1, and said model is 1 VAA sub-district, and K via node arranged in the VAA sub-district, a source node and a destination node.Wherein, all K via node all is the terminal of single antenna, so this VAA sub-district constitutes a virtual MIMO (Multiple-Input Multiple-Out-put, mimo systems).Suppose that an OFDM symbol has the N number of sub-carrier, the characteristic of channel all is flatness decline on each subcarrier, and each node all is half-duplex operation, and time domain and frequency domain are all synchronous.

Concrete communication process is following: all communication nodes all adopt TDMA (Time Division Multiple Access; Time division multiple access) mode; Phase I; Source node sends signal and gives destination node and via node, and only some participation in possible at this moment K the via node also might be that K via node all participated in.The information that second stage, via node decoding earlier institute will send, coding forwarding again after the correct decoding, sends to destination node with signal.At last, the destination node mode that adopts maximum rate to merge merges the signal that phase I and second stage are received.Should be noted that in the phase I each subcarrier can only be distributed to a via node, can use the subcarrier of using in the phase I in the second stage, but each subcarrier can only be used also by a via node.

Present embodiment adopts to concentrate and distributes, and at first Centralized Controller is collected all channel gain situations.Then, according to all channel gain situation, the transmission means of each number of sub-carrier of source node decision; Promptly directly send to destination node or pass through the via node transmission, and confirm concrete modulation system, comprise BPSK (Binary Phase Shift Keying; Phase-shift keying), QPSK (Quadrature Phase Shift Keying, QPSK); 8QAM (orthogonal amplitude keying a kind of), 16QAM (orthogonal amplitude keying a kind of) or the like.All very under the condition of severe, may occur not allocation bit at the channel conditions of SD (Source to Destination, source node to destination node) link and SR (Source to Relay, source node is to via node) link, promptly not modulate.

Suppose that the bit number that is sent on the subcarrier n is b _n, establish the channel gain of subcarrier n and do from source node to k via node

The channel gain of subcarrier n from the source node to the destination node is G _{S, d}(n), the channel gain of subcarrier n from k via node to destination node does

$G_{r_k,d}\left(n\right).$

Subcarrier n can transmit b _nThe computing formula of the needed signal to noise ratio of individual bit is:

$\mathrm{\γ}\left(b_n\right)=\mathrm{\ρ}(2^{{2b}_n}-1)---\left(1\right)$

Wherein, the span of parameter ρ is between 1 to 6.4.

We can draw and will send b according to signal to noise ratio _nIndividual bit desired power is:

P _req(b _n)＝γ(b _n)N ₀ (2)

Wherein, N ₀Be the bilateral power spectral density of additivity broadband white Gaussian noise, average is 0, and power is σ ²

Because each subcarrier all has two kinds of selections, arrive the destination node or the arrival destination node that direct transfers through relaying.The subcarrier n destination node desired power that direct transfers is:

$P_{s,d}^D\left(b_n\right)=P_{\mathrm{req}}\left(b_n\right)/G_{s,d}\left(n\right)---\left(3\right)$

Subcarrier n send information to via node k earlier, and via node is through decoding, coding again, and chooser carrier wave j is during with the information delivery destination node, and desired power is:

$P_{{s,r}_k,d}^C\left(b_n\right)=P_{\mathrm{req}}\left(b_n\right)\frac{G_{{s,r}_k}\left(n\right)+G_{r_k,d}\left(j\right)-G_{s,d}\left(n\right)}{G_{{s,r}_k}\left(n\right)G_{r_k,d}\left(j\right)}---\left(4\right)$

Introduce parameter β (n) ∈ 0,1}, when β (n)=1, expression subcarrier n direct transfers; Otherwise expression subcarrier n passes through relay transmission.That pass to that via node k uses when source node is subcarrier n, and via node k passes to destination node when using subcarrier j, record α _k(n, j)=1.Attention: each subcarrier is used by a via node at the most.We use G _Eq(n) represent equivalent channel gain, then can get by formula (3), (4):

$G_{\mathrm{eq}}\left(n\right)=\left\{\begin{array}{cc}{G}_{s,d}\left(n\right)& \mathrm{\β}\left(n\right)=1\\ \frac{G_{{s,r}_k}\left(n\right)G_{r_k,d}\left(j\right)}{G_{{s,r}_k}\left(n\right)+G_{r_k,d}\left(j\right)-G_{s,d}\left(n\right)}& \mathrm{\β}\left(n\right)=0\end{array}\right.---\left(5\right)$

Can know that to sum up our optimization aim is under the certain situation of power, the maximization transmission rate.If P _TotalBe gross power, R is total speed, and then target function is:

$R^{*}=\arg \underset{b_n\∈\{0~B_{\max }\}}{\max }\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{b}_n---\left(6\right)$

Constraints is: $\underset{n=1}{\overset{N}{\mathrm{\Σ}}}\frac{P_{\mathrm{Req}}\left(b_n\right)}{G_{\mathrm{Eq}}\left(n\right)}\≤P_{\mathrm{Total}---\left(7\right)}$

$\mathrm{\β}\left(n\right)+\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\α}}_k(n,j)=1---\left(8\right)$

β(n)≤1 (9)

$\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\α}}_k(n,j)\≤1---\left(10\right)$

Fig. 2 is the said multi-user collaborative ofdm system of an embodiment of the invention resource allocation methods flow chart, and as shown in Figure 2, said method comprises step:

A: the transmission mode of confirming the subcarrier that source node is adopted when sending information according to channel gain; Said transmission mode comprises the pattern of direct transferring and collaborative pattern.

Said steps A specifically comprises step:

A1: calculate the channel gain of current subcarrier i from source node to k via node

With the channel gain of current subcarrier i from k via node to destination node

In smaller value $\mathrm{Min}\{G_{{s,r}_k}\left(i\right),G_{r_k,d}\left(i\right)\}.$

A2: judge the channel gain G of current subcarrier i from the source node to the destination node _{S, d}(i) whether less than said smaller value

If judge that the transmission mode of current subcarrier i is collaborative pattern; Otherwise, judge that the transmission mode of current subcarrier i is the pattern of direct transferring.

A3: repeat said steps A 1 to A2, all be determined until the transmission mode of all subcarriers.

B:, confirm the corresponding relay node, and said via node is to the back segment subcarrier of destination node when the transmission mode of said subcarrier during for collaborative pattern.

Said step B specifically comprises step:

B1: the transmission mode of confirming in the said steps A is made the leading portion subcarrier for the subcarrier note of collaborative pattern.

B2:, from all said subcarriers, choose current subcarrier j successively for current leading portion subcarrier m; Wherein, the initial value of m is 1, and m≤M, and M representes the sum of said leading portion subcarrier; The initial value of j is 1, and j≤N, and N representes the sum of said subcarrier.

B3: for current subcarrier j, from all via nodes, choose current via node k successively, calculate corresponding equivalent channel gain then respectively; Wherein, the initial value of k is 1, and k≤K, and K representes the sum of said via node.

According to aforementioned formula 5, among the said step B3, it is that the computing formula of said equivalent channel gain is following that subcarrier m adopts the cooperative mode transmission:

$G_{\mathrm{eq}}\left(m\right)=\frac{G_{{s,r}_k}\left(m\right)G_{r_k,d}\left(j\right)}{G_{{s,r}_k}\left(m\right)+G_{r_k,d}\left(j\right)-G_{s,d}\left(m\right)}---\left(11\right)$

Wherein, G _Eq(m) represent said equivalent channel gain;

The channel gain of expression subcarrier m from source node to k via node; The channel gain of expression subcarrier j from k via node to destination node; G _{S, d}(m) channel gain of expression subcarrier m from the source node to the destination node.

B4: for current leading portion subcarrier m; Find the combination of a number of sub-carrier and via node to make said equivalent channel gain obtain maximum; With the back segment subcarrier of the subcarrier in the said combination, with the via node of the via node in the said combination as current leading portion subcarrier m correspondence as current leading portion subcarrier m correspondence.

B5: repeat said step B2 ~ B4, all find corresponding back segment subcarrier and via node until all leading portion subcarriers.

C: according to the transmission mode of said subcarrier, and said via node and said back segment subcarrier, adopting genetic algorithm is the bit of said subcarrier allocation respective numbers.

Said step C specifically comprises step:

C1: the initiation parameter that genetic algorithm is set; Said initiation parameter comprises: gross power, population number of individuals, generation gap parameter, fiducial value, crossover probability, variation probability, maximum iteration time; And individual chromosome number, and said chromosome number equals the sum of said subcarrier;

C2: create initial population as current population; Each individual chromosomal value is mapped as the quantity of the bit that each said subcarrier distributes, each individual corresponding initial solution in the promptly said initial population in the said initial population; And said chromosomal value between 0 between the said fiducial value.

C3: according to the transmission mode of the definite said subcarrier of said steps A; And said via node and the said back segment subcarrier confirmed among the said step B; Under said gross power restrictive condition, calculate total speed of each individuals in the current population, as the desired value of current population.Particularly, utilize in the current population each chromosomal value in each individuality, i.e. the bit value of each number of sub-carrier, and said equivalent channel gain calculates each number of sub-carrier carrying the power that is consumed under the corresponding bits value situation, obtains rated output P.At P during greater than gross power, the bit number zero setting of that subcarrier that the unit's of order bit consumption power is maximum, until rated output P less than gross power.Obtain total speed of each individuals, be the desired value of current population.

C4: calculate the fitness of each individuals in the current population according to the desired value of current population, select the maximum individuality of fitness.By the desired value of population, promptly total speed of each individuals in the population can shine upon the fitness of each individuals, and the ideal adaptation degree that total speed is big more is big more, and the ideal adaptation degree that total speed is more little is more little.

C5: judge whether iterations reaches said maximum iteration time, if, be the bit of said subcarrier allocation respective numbers according to chromosomal value in the individuality of said fitness maximum, process ends; Otherwise, execution in step C6.

C6: the fitness according to each individuals in the current population, current population is carried out selection operation, promptly eliminate the minimum predetermined value individuals of fitness, such as each minimum individuality of 2 fitness of eliminating.

C7: carry out interlace operation according to the current population of said crossover probability after to selection operation, the purpose of doing like this is for the subcarrier overabsorption bit of realizing that channel gain is good, the few allocation bit of the subcarrier of channel gain difference.

C8: carry out mutation operation according to the current population of said variation probability after, obtain new population, carry out said step C3 to interlace operation.Said step C8 just adjusts the bit value on the subcarrier in fact, is in order to make the good bit that subcarrier distributed of channel become big, the bit that subcarrier distributed of bad channel to be diminished equally.

Fig. 3 is the modular structure sketch map of the said multi-user collaborative ofdm system of embodiment of the invention resource allocation system, and is as shown in Figure 3, and said system comprises:

Pattern determining unit 100 is used for confirming according to channel gain the transmission mode of the subcarrier that source node is adopted when sending information; Said transmission mode comprises the pattern of direct transferring and collaborative pattern;

Collaborative mode unit 200, the transmission mode that is used for when said subcarrier is when working in coordination with pattern, to confirm the corresponding relay node, and said via node is to the back segment subcarrier of destination node;

Bit Allocation in Discrete unit 300 is used for the transmission mode according to said subcarrier, and said via node and said back segment subcarrier, and adopting genetic algorithm is the bit of said subcarrier allocation respective numbers.

Said pattern determining unit 100 further comprises:

The smaller value module is used to calculate the channel gain of current subcarrier i from source node to k via node

With the channel gain of current subcarrier i from k via node to destination node

In smaller value $\mathrm{Min}\{G_{{s,r}_k}\left(i\right),G_{r_k,d}\left(i\right)\};$

The mode decision module is used for the channel gain G from the source node to the destination node at current subcarrier i _{S, d}(i) less than said smaller value The time, judge that the transmission mode of subcarrier i is collaborative pattern; And, at the channel gain G of current subcarrier i from the source node to the destination node _{S, d}(i) more than or equal to said smaller value

The time, judge that the transmission mode of subcarrier i is the pattern of direct transferring.

Said Bit Allocation in Discrete unit 300 further comprises:

Initialization module; Be used to be provided with the initiation parameter of genetic algorithm; Said initiation parameter comprises: gross power, population number of individuals, generation gap parameter, fiducial value, crossover probability, variation probability, maximum iteration time; And individual chromosome number, and said chromosome number equals the sum of said subcarrier;

Initial population is created module, is used to create initial population, and offers the desired value computing module; Each individual chromosomal value is mapped as the quantity of the bit that each said subcarrier distributes in the said initial population, and said chromosomal value between 0 between the said fiducial value;

Said desired value computing module is used for the transmission mode according to said subcarrier, and said via node and said back segment subcarrier, under said gross power restrictive condition, calculates total speed of each individuals in the current population, as the desired value of current population;

The fitness computing module is used for calculating according to the desired value of current population the fitness of current each individuals of population, and selects the maximum individuality of fitness;

The Bit Allocation in Discrete module is used to write down iterations, and when iterations reaches said maximum iteration time, is the bit of said subcarrier allocation respective numbers according to chromosomal value in the individuality of fitness maximum;

Select module, be used for fitness, current population is carried out selection operation according to current each individuals of population;

Cross module is used for carrying out interlace operation according to the current population of said crossover probability after to selection operation;

The variation module is used for carrying out mutation operation according to the current population of said variation probability after to interlace operation, obtains new population, offers said desired value computing module.

Contrast the data rate of the legacy system of bit algorithms such as system of the present invention and employing below through emulation.Fig. 4 is the throughput contrast sketch map of system of the present invention and legacy system, and wherein, GA representes system of the present invention, and EBA representes legacy system.In the emulation experiment, except source node and destination node, via node is counted K=1 or 2, and via node is between source node and destination node, and its distance to two ends is the same, so path fading is the same.Suppose that the path fading coefficient is 4, the subcarrier number N=64 of each OFDM symbol, the modulation system that each subcarrier can be selected is BPSK, QPSK, 8PSK, 16QAM, i.e. b _nOptional maximum B _MaxBe 4.Population number of individuals NIND=40, maximum iteration time is 10, generation gap GGAP=0.8 adopts single-point to intersect.

Can see that from Fig. 4 under the certain situation of power, the throughput of system of the present invention is obviously greater than legacy system.Throughput on average has more 5bps.This is because wait bit to distribute the channel gain of not considering each number of sub-carrier, only is to be the identical bit number of each subcarrier allocation.And genetic algorithm will be according to channel conditions, the bit number of adaptive modulation allocation.Can also see that from Fig. 4 along with increasing of via node quantity, the throughput increase of legacy system is very fast, this is because many relayings provide space diversity.But legacy system is still less than system of the present invention, and space diversity promotes though this is, it can not self adaptation allocated channel gain bit.In addition, can also see that the energy that genetic algorithm unit's bit is consumed will lack a lot, therefore, is well suited for the situation of power limited.

The embodiment of the invention said multi-user collaborative ofdm system resource allocation methods and system; At first confirm the transmission mode of each number of sub-carrier according to channel gain; And, adopt the bit number that genetic algorithm is carried each number of sub-carrier to carry out the non-equivalent distribution at last, under the certain situation of power to further definite via node of the subcarrier of collaborative transmission and back segment subcarrier; Can significantly improve the throughput of ofdm system, be with a wide range of applications.

Above execution mode only is used to explain the present invention; And be not limitation of the present invention; The those of ordinary skill in relevant technologies field under the situation that does not break away from the spirit and scope of the present invention, can also be made various variations and modification; Therefore all technical schemes that are equal to also belong to category of the present invention, and scope of patent protection of the present invention should be defined by the claims.

Claims (8)

1. a multi-user collaborative ofdm system resource allocation methods is characterized in that, comprises step:

A: the transmission mode of confirming the subcarrier that source node is adopted when sending information according to channel gain; Said transmission mode comprises the pattern of direct transferring and collaborative pattern;

B:, confirm the corresponding relay node, and said via node is to the back segment subcarrier of destination node when the transmission mode of said subcarrier during for collaborative pattern;

C: according to the transmission mode of said subcarrier, and said via node and said back segment subcarrier, adopting genetic algorithm is the bit of said subcarrier allocation respective numbers.

2. the method for claim 1 is characterized in that, said steps A specifically comprises step:

A1: calculate the channel gain of current subcarrier i from source node to k via node

With the channel gain of current subcarrier i from k via node to destination node

In smaller value $\mathrm{Min}\{G_{{s,r}_k}\left(i\right),G_{r_k,d}\left(i\right)\};$

A2: judge the channel gain G of current subcarrier i from the source node to the destination node _{S, d}(i) whether less than said smaller value

If judge that the transmission mode of current subcarrier i is collaborative pattern; Otherwise, judge that the transmission mode of current subcarrier i is the pattern of direct transferring;

A3: repeat said steps A 1 to A2, all be determined until the transmission mode of all subcarriers.

3. the method for claim 1 is characterized in that, said step B specifically comprises step:

B1: the transmission mode of confirming in the said steps A is made the leading portion subcarrier for the subcarrier note of collaborative pattern;

B2:, from all said subcarriers, choose current subcarrier j successively for current leading portion subcarrier m; Wherein, the initial value of m is 1, and m≤M, and M representes the sum of said leading portion subcarrier; The initial value of j is 1, and j≤N, and N representes the sum of said subcarrier;

B3: for current subcarrier j, from all via nodes, choose current via node k successively, calculate corresponding equivalent channel gain then respectively; Wherein, the initial value of k is 1, and k≤K, and K representes the sum of said via node;

B4: for current leading portion subcarrier m; Find the combination of a number of sub-carrier and via node to make said equivalent channel gain obtain maximum; With the back segment subcarrier of the subcarrier in the said combination, with the via node of the via node in the said combination as current leading portion subcarrier m correspondence as current leading portion subcarrier m correspondence;

B5: repeat said step B2 ~ B4, all find corresponding back segment subcarrier and via node until all leading portion subcarriers.

4. method as claimed in claim 3 is characterized in that, among the said step B3, the computing formula of said equivalent channel gain is following:

$G_{\mathrm{eq}}=\left(m\right)=\frac{G_{{s,r}_k}\left(m\right)G_{r_k,d}\left(j\right)}{G_{{s,r}_k}\left(m\right)+G_{r_k,d}\left(j\right)-G_{s,d}\left(m\right)};$

Wherein, G _Eq(m) represent said equivalent channel gain;

The channel gain of expression subcarrier m from source node to k via node;

The channel gain of expression subcarrier j from k via node to destination node; G _{S, d}(m) channel gain of expression subcarrier m from the source node to the destination node.

5. the method for claim 1 is characterized in that, said step C specifically comprises step:

C1: the initiation parameter that genetic algorithm is set; Said initiation parameter comprises: gross power, population number of individuals, generation gap parameter, fiducial value, crossover probability, variation probability, maximum iteration time; And individual chromosome number, and said chromosome number equals the sum of said subcarrier;

C2: create initial population as current population; Each individual chromosomal value is mapped as the quantity of the bit that each said subcarrier distributes in the said initial population, and said chromosomal value between 0 between the said fiducial value;

C3: according to the transmission mode of the definite said subcarrier of said steps A; And said via node and the said back segment subcarrier confirmed among the said step B; Under the restrictive condition of said gross power, calculate total speed of each individuals in the current population, as the desired value of current population;

C4: calculate the fitness of each individuals in the current population according to the desired value of current population, select the maximum individuality of fitness;

C5: judge whether iterations reaches said maximum iteration time, if, be the bit of said subcarrier allocation respective numbers according to chromosomal value in the individuality of fitness maximum, process ends; Otherwise, execution in step C6;

C6: the fitness according to each individuals in the current population, carry out selection operation to current population;

C7: carry out interlace operation according to the current population of said crossover probability after to selection operation;

C8: carry out mutation operation according to the current population of said variation probability after, obtain new population, carry out said step C3 to interlace operation.

6. multi-user collaborative ofdm system resource allocation system is characterized in that said system comprises:

Pattern determining unit is used for confirming according to channel gain the transmission mode of the subcarrier that source node is adopted when sending information; Said transmission mode comprises the pattern of direct transferring and collaborative pattern;

Collaborative mode unit, the transmission mode that is used for when said subcarrier is when working in coordination with pattern, to confirm the corresponding relay node, and said via node is to the back segment subcarrier of destination node;

The Bit Allocation in Discrete unit is used for the transmission mode according to said subcarrier, and said via node and said back segment subcarrier, and adopting genetic algorithm is the bit of said subcarrier allocation respective numbers.

7. system as claimed in claim 6 is characterized in that, said pattern determining unit comprises:

The smaller value module is used for calculating the channel gain

of current subcarrier i from source node to k via node and the smaller value

of the channel gain

of current subcarrier i from k via node to destination node

The mode decision module is used for the channel gain G from the source node to the destination node at current subcarrier i _{S, d}(i) less than said smaller value The time, judge that the transmission mode of subcarrier i is collaborative pattern; And, at the channel gain G of current subcarrier i from the source node to the destination node _{S, d}(i) more than or equal to said smaller value

The time, judge that the transmission mode of subcarrier i is the pattern of direct transferring.

8. system as claimed in claim 6 is characterized in that, said Bit Allocation in Discrete unit comprises:

Initialization module; Be used to be provided with the initiation parameter of genetic algorithm; Said initiation parameter comprises: gross power, population number of individuals, generation gap parameter, fiducial value, crossover probability, variation probability, maximum iteration time; And individual chromosome number, and said chromosome number equals the sum of said subcarrier;

Initial population is created module, is used to create initial population, and offers the desired value computing module; Each individual chromosomal value is mapped as the quantity of the bit that each said subcarrier distributes in the said initial population, and said chromosomal value between 0 between the said fiducial value;

Said desired value computing module is used for the transmission mode according to said subcarrier, and said via node and said back segment subcarrier, under said gross power restrictive condition, calculates total speed of each individuals in the current population, as the desired value of current population;

The fitness computing module is used for calculating according to the desired value of current population the fitness of current each individuals of population, and selects the maximum individuality of fitness;

The Bit Allocation in Discrete module is used to write down iterations, and when iterations reaches said maximum iteration time, is the bit of said subcarrier allocation respective numbers according to chromosomal value in the individuality of fitness maximum;

Select module, be used for fitness, current population is carried out selection operation according to current each individuals of population;

Cross module is used for carrying out interlace operation according to the current population of said crossover probability after to selection operation;

The variation module is used for carrying out mutation operation according to the current population of said variation probability after to interlace operation, obtains new population, offers said desired value computing module.

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