CN103051583A - OFDMA (orthogonal frequency division multiple access) resource distribution method based on rate adaption - Google Patents

Abstract

The invention discloses an OFDMA (orthogonal frequency division multiple access) resource distribution method based on rate adaption. The method comprises the following steps of: firstly, carrying out subcarrier number distribution between users; then carrying out subcarrier distribution; and finally, carrying out power distribution. The OFDMA resource distribution method based on the rate adaption has the advantages that the subcarrier is distributed on the basis of a proportionality coefficient corresponding to the preset rate requirement between users in the subcarrier number distribution process; in the subcarrier distribution process, the subcarrier is distributed on the basis of the ratio of the maximized minimum rate requirement and a corresponding proportionality coefficient; then, the rest subcarrier is distributed to a user with the maximum channel gain; according to the subcarrier distribution mode, the system handling capacity can be better improved; and in the power distribution process, the channel gain is distributed in proportion by the proportionality coefficient corresponding to the user rate requirement and a relative channel gain. The OFDMA resource distribution method based on the rate adaption is easy to realize, and has a low computation complexity.

Description

A kind of OFDMA resource allocation methods based on rate adaptation

Technical field

The present invention relates to a kind of resource allocation techniques, especially relate to a kind of OFDMA resource allocation methods based on rate adaptation.

Background technology

Multi-user orthogonal frequency division multiple access (OFDMA, Orthogonal Frequency Division MultipleAccess) be the multi-access mode of next generation wireless communication physical layer first-selection, it is based on OFDM(Orthogonal Frequency DivisionMultiplexing, OFDM) a kind of wireless access way of modulation system, have availability of frequency spectrum height, anti-fading ability is strong, transmission rate is high, resource is distributed flexibly and supports simultaneously the characteristics such as a plurality of users, be considered to the key technology of NGBW access way.The OFDMA multiple access system is divided into transmission bandwidth a series of sub-carrier set of the non-overlapping copies of quadrature, different sub-carrier set is distributed to different users realize multiple access, and can be according to channel status, dynamically available bandwidth resources is distributed to the user who needs, be easy to realize the optimization utilization of system resource, therefore it is to guarantee QoS of customer, and improves the important means of power system capacity and the availability of frequency spectrum, has become one of focus of Chinese scholars research.

The Dynamic Resource Allocation for Multimedia problem can effectively be utilized user's diversity, improves the capacity of system.In ofdm system, difference according to optimization aim, resource allocation problem generally can be divided into two kinds of forms: a kind of minimized MA of transmitting power (MarginAdaptive) problem that is based on, and it is under the condition that user data rate is fixed, and total transmitting power is reached minimize; Another kind is based on the maximized RA(RateAdaptive of speed) problem, it is under the condition that gross power is fixed, and guarantees that the capacity of system reaches maximization.For the RA problem, be divided into static resource allocation and Dynamic Resource Allocation for Multimedia, wherein static resource allocation is that each user of OFDM-TDMA(is assigned with one group of predetermined time slot,

This user can use all subcarriers in given time slot) and each user of OFDM-FDMA(be assigned with the subcarrier of one group of predetermined sequential frequency band, this user uses that group subcarrier of being got regularly in each OFDM symbol); Dynamic Resource Allocation for Multimedia, namely each user can use at different time slots unfixed subcarrier, and the foundation of distribution is that each user is in the instantaneous characteristic of channel of each subchannel.At present existing many typical dynamically OFDM adaptive resource allocation methods are suggested, as based on the fairness resource allocation method of maximum-minimum (Max-Min) criterion, based on the resource allocation methods of equitable proportion, based on the resource allocation methods of weight etc.In the Max-Min method, at first gross power is averagely allocated to each subcarrier, then adopt the method realization power system capacity of the minimum user rate of maximization and the maximization of user fairness, because the method is based on average power allocation, do not consider the time-varying characteristics of channel, thereby be a kind of method of suboptimum.In the resource allocation methods of equitable proportion, Shen has proposed the Resource Allocation Formula under the proportional constraints of speed in the OFDMA system, at first finding out optimum subchannel based on the Max-Min method distributes, then adopt the iterative search method to find out optimum power division, yet this method has been carried out a large amount of iterative searchs, and computation complexity is very high.

Summary of the invention

It is low that technical problem to be solved by this invention provides a kind of computation complexity, and can realize the transmission rate maximization of total transmission, and can satisfy user's rate requirement and the OFDMA resource allocation methods based on rate adaptation that fairness requires.

The present invention solves the problems of the technologies described above the technical scheme that adopts: a kind of OFDMA resource allocation methods based on rate adaptation is characterized in that may further comprise the steps:

1. the proportionality coefficient corresponding according to the rate requirement of each user preset determined original allocation to each user's number of sub carrier wave, is designated as N for k user's number of sub carrier wave original allocation _k', then according to the number of sub carrier wave of original allocation to K user, calculate the number of sub carrier wave that the first beginning and end are assigned with, be designated as N ^*,

Wherein, 1≤k≤K, K represents total number of users, N represents total number of sub-carriers;

2. give each user's number of sub carrier wave according to original allocation, the subcarrier that should be assigned with for each user assignment, in assigning process, always preferentially give rate requirement the channel best with the relative channel gain of user assignment of the ratio minimum of corresponding proportionality coefficient, until the number of sub carrier wave that all users initially should be assigned with is met; Then remaining subcarrier is distributed to the user of relative channel gain maximum;

3. carry out power division at each subcarrier of distributing to each user, the power of distributing on k user's n the subcarrier is designated as P _{K, n}

Described step 1. in original allocation give k user's number of sub carrier wave N _k' definite process be: proportionality coefficient corresponding to rate requirement of supposing k user preset is θ _k, then according to θ _kCalculate original allocation to k user's number of sub carrier wave N _k', Wherein, θ _iProportionality coefficient corresponding to rate requirement that represents i user,

For rounding symbol downwards.

Described step detailed process 2. is:

2.-1, each user's rate requirement is initialized as 0, the subcarrier set is designated as Ω _N, Ω _N={ z ₁, z ₂..., z _n..., z _N, user's set is designated as Ω _K, Ω _K={ u ₁, u ₂..., u _k..., u _K, average power is designated as p,

The weighted factor whether k corresponding n the subcarrier of user is assigned with is designated as ρ _{K, n}, ρ _{K, n}K corresponding n subcarrier of user of=1 expression has been assigned with ρ _{K, n}K corresponding n subcarrier of user of=0 expression is not assigned with, wherein, and 1≤n≤N, z ₁Represent the 1st subcarrier, z ₂Represent the 2nd subcarrier, z _nRepresent n subcarrier, z _NRepresent N subcarrier, u ₁Represent the 1st user, u ₂Represent the 2nd user, u _kRepresent k user, u _KRepresent K user, P _TotalRepresent total transmitted power;

2.-2, initially give a best subcarrier of the relative channel gain of each user assignment, the subcarrier that then will distribute is gathered Ω from subcarrier _NMiddle deletion is upgraded original allocation again to each user's number of sub carrier wave and each user's rate requirement; For k user u _k, find out the maximum corresponding subcarrier of channel gain, suppose that the subcarrier of finding out is n subcarrier z _n, then with n subcarrier z _nDistribute to k user u _k, then with n subcarrier z _nFrom subcarrier set Ω _NMiddle deletion is then upgraded original allocation to k user u _kNumber of sub carrier wave N _k'=N _k'-1, and upgrade k user u _kRate requirement R _k,

Again with ρ _{K, n}Value be set to 1 and be used for n subcarrier of expression and be assigned to k user, wherein, N _k'=N _k"=" is assignment in '-1, and B represents channel width, H _{K, n}Represent k user u _kAt n subcarrier z _nOn relative channel gain, H _{K, n}=h _{K, n}| ²/ δ ², h _{K, n}Represent k user u _kAt n subcarrier z _nOn impulse response, δ ²Expression additive white Gaussian noise variance, " || " is the symbol that takes absolute value;

2.-3, judge || Ω _N|| N ^*Whether set up, if set up, then execution in step 2.-4, otherwise, execution in step 2.-5, wherein, || Ω _N|| the subcarrier set Ω after the allocation of subcarriers is deleted in expression _NIn the number of subcarrier;

2.-4, distribute the subcarrier that should be assigned with: the subcarrier that also is not assigned with in the subcarrier that should be assigned with continues to distribute to each user, in assigning process, at first find out the user of rate requirement and the ratio minimum of corresponding proportionality coefficient, suppose that the user who finds out is k user u _k, then find out again k user u _kThe corresponding subcarrier of channel gain of maximum, suppose that the subcarrier of finding out is n subcarrier z _n, then work as N _k' 0 o'clock with n subcarrier z _nDistribute to k user u _k, then with n subcarrier z _nFrom subcarrier set Ω _NMiddle deletion is then upgraded original allocation to k user u _kNumber of sub carrier wave N _k'=N _k'-1, and upgrade k user u _kRate requirement R _k, Afterwards with ρ _{K, n}Value be set to 1 and be used for n subcarrier of expression and be assigned to k user, work as N _k'=0 o'clock with k user from user's set omega _KMiddle deletion is returned step again and 2.-3 is continued to carry out, wherein, $R_k=R_k+\frac{B}{N}{\log }_2(1+{\mathrm{pH}}_{k,n})$ In "=" be assignment, $R_k=R_k+\frac{B}{N}{\log }_2(1+{\mathrm{ph}}_{k,n})$ In the R on "=" left side _kK user u after expression is upgraded _kRate requirement, "=" the right R _kFront k user u upgraded in expression _kRate requirement;

2.-5, distribute remaining subcarrier: with remaining N ^*Individual sub-allocation of carriers is given each user, and detailed process is: be this N ^*Individual subcarrier is found out respectively the user of relative channel gain maximum, for this N ^*N in the individual subcarrier ^*Individual subcarrier is supposed this n ^*Individual subcarrier is n subcarrier in N the subcarrier, and the user of the relative channel gain maximum found out of hypothesis is k user u _k, then with n subcarrier z _nDistribute to k user u _k, then upgrade the number of sub carrier wave N that the first beginning and end are assigned with ^*=N ^*-1, and upgrade k user u _kRate requirement R _k,

Again with ρ _{K, n}Value be set to 1 and be used for n subcarrier of expression and be assigned to k user, wherein, 1≤n ^*≤ N ^*, N ^*=N ^*"=" is assignment in-1,

In "=" be assignment,

In the R on "=" left side _kK user u after expression is upgraded _kRate requirement, "=" the right R _kFront k user u upgraded in expression _kRate requirement.

Described step is distributed to the power P on k user's n the subcarrier in 3. _{K, n}Concrete acquisition process be:

3.-1, between K user, carry out power division, the gross power of distributing to k user is designated as P _{K, tot},

Wherein, 1≤k≤K, K represents total number of users, θ _kProportionality coefficient corresponding to rate requirement that represents k user preset, θ _iProportionality coefficient corresponding to rate requirement that represents i user, p _TotalRepresent total transmitted power;

3.-2, carry out power division at each subcarrier of distributing to each user, for k user, the subcarrier of supposing finally to distribute to it is the 1st subcarrier to the N _kIndividual subcarrier is then with this N _kThe power that distributes on n' the subcarrier in the individual subcarrier is designated as P _{K, n '},

Wherein, 1＜N _k＜N, 1≤n '≤N _k, N _kK user's number of sub carrier wave, H are finally distributed in expression _{Kn '}Represent that k user is at this N _kThe relative channel gain of correspondence on the individual subcarrier of n ' in the individual subcarrier, H _{K, i '}Represent that k user is at this N _kThe relative channel gain of correspondence on the individual subcarrier of i ' in the individual subcarrier.

Compared with prior art, the invention has the advantages that: be based in the number of sub carrier wave assigning process that proportionality coefficient corresponding to predefined rate requirement distributes between the user; Be based on first the score gamete carrier wave of maximization minimum-rate requirement and corresponding proportionality coefficient in the subcarrier assigning process, then the subcarrier that is left distributed to the user of channel gain maximum, this sub-carrier distribution manner more can improve the throughput of system; In the power division process, be based on proportionality coefficient corresponding to user's rate requirement and the pro-rata of relative channel gain, not only be easy to realize, and computation complexity be low.

Description of drawings

Fig. 1 is for adopting TDMA method, Shen method and the inventive method to carry out the schematic diagram that resource distributes all user's total capacities of obtaining to change with number of users;

Fig. 2 is for adopting TDMA method, Shen method and the inventive method to carry out the schematic diagram that resource distributes the user fairness sex factor FP that obtains to change with number of users;

Fig. 3 distributes the performed time with the schematic diagram of number of users variation for adopting Shen method and the inventive method to carry out resource under same channel condition.

Embodiment

Embodiment is described in further detail the present invention below in conjunction with accompanying drawing.

The target of the present invention proposes a kind of OFDMA resource allocation methods based on rate adaptation satisfies each user's rate requirement and fairness requirement when being the maximization overall transmission rate, it is to be based upon on the basis of OFDMA optimal resource allocation model of down link, and the optimal resource allocation model is as follows: $\begin{array}{c}s.t.\underset{k=1}{\overset{k}{\mathrm{\Σ}}}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{p}_{k,n}\≤P_{\mathrm{total}}---\left(a\right)\\ \begin{array}{cc}{p}_{k,n}\≥0& \∀k,n---\left(b\right)\end{array}\\ \begin{array}{cc}{\mathrm{\ρ}}_{k,n}\∈\left\{\mathrm{0,1}\right\}& \∀k,n---\left(c\right)\end{array}\\ \begin{array}{cc}\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{\mathrm{\ρ}}_{k,n}=1& \∀n---\left(d\right)\end{array}\\ R_1:R_2:...:R_K={\mathrm{\θ}}_1:{\mathrm{\θ}}_2:...:{\mathrm{\θ}}_k---\left(e\right)\end{array},$ Wherein, K represents total number of user, and N represents total number of subcarrier, ρ _{K, n}Be used for the weighted factor whether n subcarrier of expression is assigned to k user, if n subcarrier is assigned to k user, ρ then _{K, n}=1, if n subcarrier is not assigned to k user, ρ then _{K, n}=0, B represents channel width, p _{K, n}Represent the transmitted power of k user on n subcarrier, H _{K, n}Represent the relative channel gain of k user on n subcarrier, H _{K, n}=| h _{K, n}| ²/ δ ², h _{K, n}Represent k the impulse response of user on n subcarrier, δ ²Expression additive white Gaussian noise variance, " || " is the symbol that takes absolute value, P _TotalRepresent total transmitted power, R ₁The rate requirement that represents the 1st user, R ₂The rate requirement that represents the 2nd user, R _KThe rate requirement that represents K user, θ ₁Proportionality coefficient corresponding to rate requirement that represents the 1st user, θ ₂Proportionality coefficient corresponding to rate requirement that represents the 2nd user, θ K represents K user's proportionality coefficient corresponding to rate requirement, constraints (a) represents that the summation of the transmitted power of all users on all subcarriers can not surpass total transmitted power, constraints (b) represents that the transmitted power of each user on each subcarrier should be more than or equal to 0, whether n subcarrier of constraints (c) expression is assigned to k user, constraints (d) represents each subcarrier only for a user, and constraints (e) is the proportionality coefficient value of setting for the fairness of guaranteeing the user.

In order to weigh the fairness situation of user under different condition, in this definition fairness factor, be designated as FP,

Wherein, R _kThe rate requirement that represents k user, θ _kProportionality coefficient corresponding to rate requirement that represents k user, from

In can find out FP≤1, FP illustrates that more near 1 fairness is better, fairness obtains maximum satisfying during FP=1.

The inventive method specifically may further comprise the steps:

1. the proportionality coefficient corresponding according to the rate requirement of each user preset determined original allocation to each user's number of sub carrier wave, is designated as N for k user's number of sub carrier wave original allocation _k', then according to the number of sub carrier wave of original allocation to K user, calculate the number of sub carrier wave that the first beginning and end are assigned with, be designated as N ^*,

Wherein, 1≤k≤K, K represents total number of users, N represents total number of sub-carriers.

In this specific embodiment, step 1. in original allocation give k user's number of sub carrier wave N _k' definite process be: proportionality coefficient corresponding to rate requirement of supposing k user preset is θ _k, then according to θ _kCalculate original allocation to k user's number of sub carrier wave N _k',

Wherein, θ _iProportionality coefficient corresponding to rate requirement that represents i user,

For rounding symbol downwards.

2. give each user's number of sub carrier wave according to original allocation, the subcarrier that should be assigned with for each user assignment, in assigning process, always preferentially give rate requirement the channel best with the relative channel gain of user assignment of the ratio minimum of corresponding proportionality coefficient, until the number of sub carrier wave that all users initially should be assigned with is met; Then remaining subcarrier is distributed to the user of relative channel gain maximum.

In this specific embodiment, step detailed process 2. is:

2.-1, each user's rate requirement is initialized as 0, the subcarrier set is designated as Ω _N, Ω _N={ z ₁, z ₂..., z _n..., z _N, user's set is designated as Ω _K, Ω _K={ u ₁, u ₂..., u _k..., u _K, average power is designated as p,

The weighted factor whether k corresponding n the subcarrier of user is assigned with is designated as ρ _{K, n}, ρ _{K, n}K corresponding n subcarrier of user of=1 expression has been assigned with ρ _{K, n}K corresponding n subcarrier of user of=0 expression is not assigned with, wherein, and 1≤n≤N, z ₁Represent the 1st subcarrier, z ₂Represent the 2nd subcarrier, z _nRepresent n subcarrier, z _NRepresent N subcarrier, u ₁Represent the 1st user, u ₂Represent the 2nd user, u _kRepresent k user, u _KRepresent K user, P _TotalRepresent total transmitted power.

2.-2, initially give a best subcarrier of the relative channel gain of each user assignment, the subcarrier that then will distribute is gathered Ω from subcarrier _NMiddle deletion is upgraded original allocation again to each user's number of sub carrier wave and each user's rate requirement; For k user u _k, find out the maximum corresponding subcarrier of channel gain, suppose that the subcarrier of finding out is n subcarrier z _n, then with n subcarrier z _nDistribute to k user u _k, then with n subcarrier z _nFrom subcarrier set Ω _NMiddle deletion is then upgraded original allocation to k user u _kNumber of sub carrier wave N _k'=N _k'-1, and upgrade k user u _kRate requirement R _k,

Again with ρ _{K, n}Value be set to 1 and be used for n subcarrier of expression and be assigned to k user, wherein, N _k'=N _k"=" is assignment in '-1, and B represents channel width, H _{K, n}Represent k user u _kAt n subcarrier z _nOn relative channel gain, H _{K, n}=| h _{K, n}| ²/ δ ², h _{K, n}Represent k user u _kAt n subcarrier z _nOn impulse response, δ ²Expression additive white Gaussian noise variance, " || " is the symbol that takes absolute value.

2.-3, judge || Ω _N|| N ^*Whether set up, if set up, then execution in step 2.-4, otherwise, execution in step 2.-5, wherein, || Ω _N|| the subcarrier set Ω after the allocation of subcarriers is deleted in expression _NIn the number of subcarrier.

2.-4, distribute the subcarrier that should be assigned with: the subcarrier that also is not assigned with in the subcarrier that should be assigned with continues to distribute to each user, in assigning process, at first find out the user of rate requirement and the ratio minimum of corresponding proportionality coefficient, suppose that the user who finds out is k user u _k, then find out again k user u _kThe corresponding subcarrier of channel gain of maximum, suppose that the subcarrier of finding out is n subcarrier z _n, then work as N _k' 0 o'clock with n subcarrier z _nDistribute to k user u _k, then with n subcarrier z _nFrom subcarrier set Ω _NMiddle deletion is then upgraded original allocation to k user u _kNumber of sub carrier wave N _k'=N _k'-1, and upgrade k user u _kRate requirement R _k,

Afterwards with ρ _{K, n}Value be set to 1 and be used for n subcarrier of expression and be assigned to k user, work as N _k'=0 o'clock with k user from user's set omega _KMiddle deletion is returned step again and 2.-3 is continued to carry out, wherein, $R_k=R_k+\frac{B}{N}{\log }_2(1+{\mathrm{pH}}_{k,n})$ In "=" be assignment, $R_k=R_k+\frac{B}{N}{\log }_2(1+{\mathrm{pH}}_{k,n})$ In the R on "=" left side _kK user u after expression is upgraded _kRate requirement, "=" the right R _kFront k user u upgraded in expression _kRate requirement.

2.-5, distribute remaining subcarrier: with remaining N ^*Individual sub-allocation of carriers is given each user, and the criterion of distribution is: the subcarrier of relative channel gain maximum is distributed to the user, and detailed process is: be this N ^*Individual subcarrier is found out respectively the user of relative channel gain maximum, for this N ^*N in the individual subcarrier ^*Individual subcarrier is supposed this n ^*Individual subcarrier is n subcarrier in N the subcarrier, and the user of the relative channel gain maximum found out of hypothesis is k user u _k, then with n subcarrier z _nDistribute to k user u _k, then upgrade the number of sub carrier wave N that the first beginning and end are assigned with ^*=N ^*-1, and upgrade k user u _kRate requirement R _k,

Again with ρ _{K, n}Value be set to 1 and be used for n subcarrier of expression and be assigned to k user, wherein, 1≤n ^*≤ N ^*, N ^*=N ^*" " is assignment in-1, $R_k=R_k+\frac{B}{N}{\log }_2(1+{\mathrm{pH}}_{k,n})$ In "=" be assignment, $R_k=R_k+\frac{B}{N}{\log }_2(1+{\mathrm{pH}}_{k,n})$ In the R on "=" left side _kK user u after expression is upgraded _kRate requirement, "=" the right R _kFront k user u upgraded in expression _kRate requirement.

3. carry out power division at each subcarrier of distributing to each user, the power of distributing on k user's n the subcarrier is designated as P _{K, n}

In this specific embodiment, step is distributed to the power P on k user's n the subcarrier in 3. _{K, n}Concrete acquisition process be:

3.-1, between K user, carry out power division, the gross power of distributing to k user is designated as P _{K, tot},

Wherein, 1≤k≤K, K represents total number of users, θ _kProportionality coefficient corresponding to rate requirement that represents k user preset, θ _iProportionality coefficient corresponding to rate requirement that represents i user, P _TotalRepresent total transmitted power.

3.-2, carry out power division at each subcarrier of distributing to each user, for k user, the subcarrier of supposing finally to distribute to it is the 1st subcarrier to the N _kIndividual subcarrier is then with this N _kThe power that distributes on the individual subcarrier of n ' in the individual subcarrier is designated as P _{K, n '},

Wherein, 1＜N _k＜N, 1≤n '≤N _k, N _kK user's number of sub carrier wave, H are finally distributed in expression _{Kn '}Represent that k user is at this N _kThe relative channel gain of correspondence on the individual subcarrier of n ' in the individual subcarrier, H _{K, i '}Represent that k user is at this N _kThe relative channel gain of correspondence on the individual subcarrier of i ' in the individual subcarrier.

Below for validity and the feasibility of the inventive method are described by experiment.

At this, the simulated environment of employing is 6 footpath frequency selectivity Raleigh channels, and maximum Doppler frequency-shift is 30HZ, and time delay expands to 5 μ s, and total number of sub carrier wave is 64, and system bandwidth is 1MHz, and total transmitted power is 1W, and the white Gaussian noise power spectral density is N ₀=10 ^-8, number of users is 2～10, the Monte Carlo simulation number of times is 2000 times.The below analyzes validity and the feasibility of the inventive method from power system capacity, user fairness sex factor, time of implementation three aspects:.

Fig. 1 has provided employing TDMA method, Shen method and the inventive method are carried out resource and are distributed (subcarrier, bit and power) schematic diagram that changes with number of users of all user's total capacities of obtaining, as can be seen from Figure 1 along with the increase of number of users, the inventive method, the power system capacity that the Shen method obtains increases thereupon, and the power system capacity that the TDMA method obtains is substantially constant, this is because the inventive method, the Shen method is dynamic adaptive resource allocation method, utilized multi-user's diversity principle, and be better than static TDMA resource allocation methods, simultaneously along with the power system capacity of increase the inventive method of the user power system capacity apparently higher than the Shen method.

Fig. 2 has provided employing TDMA method, Shen method and the inventive method are carried out the schematic diagram that resource distributes the system user fairness factor FP obtain to change with number of users, as can be seen from Figure 2 along with the increase of number of users, the Shen method has embodied user fairness, its fairness factor is near 1, the fairness factor that the inventive method and TDMA method obtain is all on a declining curve, this is because well taken into account user's fairness when Shen method maximized system capacity, and the inventive method has maximized power system capacity in the slight reduction user fairness, compare the TDMA method, the inventive method has preferably fairness, and its fairness factor is 0.88～0.98.

Fig. 3 has provided and has adopted Shen method and the inventive method to carry out the schematic diagram that the performed time of resource distribution changes with number of users under same channel condition, as can be seen from Figure 3 along with the increase of number of users, the inventive method is carried out resource and is distributed required time to have increased slightly, and Shen method required time is and increases progressively trend, this is because power division is based on user's speed proportionality coefficient and the pro-rata of relative channel gain in the inventive method, it has very low complexity, be easy to realize, and the Shen method adopts the iterative search method to find out optimum power division, carry out a large amount of iterative searchs, needed very high computation complexity.

Claims (4)

1. OFDMA resource allocation methods based on rate adaptation is characterized in that may further comprise the steps:

1. the proportionality coefficient corresponding according to the rate requirement of each user preset determined original allocation to each user's number of sub carrier wave, is designated as N for k user's number of sub carrier wave original allocation _k', then according to the number of sub carrier wave of original allocation to K user, calculate the number of sub carrier wave that the first beginning and end are assigned with, be designated as N ^*,

Wherein, 1≤k≤K, K represents total number of users, N represents total number of sub-carriers;

2. give each user's number of sub carrier wave according to original allocation, the subcarrier that should be assigned with for each user assignment, in assigning process, always preferentially give rate requirement the channel best with the relative channel gain of user assignment of the ratio minimum of corresponding proportionality coefficient, until the number of sub carrier wave that all users initially should be assigned with is met; Then remaining subcarrier is distributed to the user of relative channel gain maximum;

3. carry out power division at each subcarrier of distributing to each user, the power of distributing on k user's n the subcarrier is designated as P _{K, n}

2. a kind of OFDMA resource allocation methods based on rate adaptation according to claim 1 is characterized in that original allocation was to k user's number of sub carrier wave N during described step 1. _k' definite process be: proportionality coefficient corresponding to rate requirement of supposing k user preset is θ _k, then according to θ _kCalculate original allocation to k user's number of sub carrier wave N _k',

Wherein, θ _iProportionality coefficient corresponding to rate requirement that represents i user,

For rounding symbol downwards.

3. a kind of OFDMA resource allocation methods based on rate adaptation according to claim 1 and 2 is characterized in that described step detailed process 2. is:

2.-1, each user's rate requirement is initialized as 0, the subcarrier set is designated as Ω _N, Ω _N={ z ₁, z ₂..., z _n..., z _N, user's set is designated as Ω _K, Ω _K={ u ₁, u ₂..., u _k..., u _K, average power is designated as p,

The weighted factor whether k corresponding n the subcarrier of user is assigned with is designated as ρ _{K, n}, ρ _{K, n}K corresponding n subcarrier of user of=1 expression has been assigned with ρ _{K, n}K corresponding n subcarrier of user of=0 expression is not assigned with, wherein, and 1≤n≤N, z ₁Represent the 1st subcarrier, z ₂Represent the 2nd subcarrier, z _nRepresent n subcarrier, z _NRepresent N subcarrier, u ₁Represent the 1st user, u ₂Represent the 2nd user, u _kRepresent k user, u _KRepresent K user, P _TotalRepresent total transmitted power;

2.-2, initially give a best subcarrier of the relative channel gain of each user assignment, the subcarrier that then will distribute is gathered Ω from subcarrier _NMiddle deletion is upgraded original allocation again to each user's number of sub carrier wave and each user's rate requirement; For k user u _k, find out the maximum corresponding subcarrier of channel gain, suppose that the subcarrier of finding out is n subcarrier z _n, then with n subcarrier z _nDistribute to k user u _k, then with n subcarrier z _nFrom subcarrier set Ω _NMiddle deletion is then upgraded original allocation to k user u _kNumber of sub carrier wave N _k'=N _k'-1, and upgrade k user u _kRate requirement R _k,

Again with ρ _{K, n}Value be set to 1 and be used for n subcarrier of expression and be assigned to k user, wherein, N _k'=N _k"=" is assignment in '-1, and B represents channel width, H _{K, n}Represent k user u _kAt n subcarrier z _nOn relative channel gain, H _{K, n}=| h _{K, n}| ²/ δ ², h _{K, n}Represent k user u _kAt n subcarrier z _nOn impulse response, δ ²Expression additive white Gaussian noise variance, " || " is the symbol that takes absolute value;

2.-3, judge || Ω _N|| N ^*Whether set up, if set up, then execution in step 2.-4, otherwise, execution in step 2.-5, wherein, || Ω _N|| the subcarrier set Ω after the allocation of subcarriers is deleted in expression _NIn the number of subcarrier;

2.-4, distribute the subcarrier that should be assigned with: the subcarrier that also is not assigned with in the subcarrier that should be assigned with continues to distribute to each user, in assigning process, at first find out the user of rate requirement and the ratio minimum of corresponding proportionality coefficient, suppose that the user who finds out is k user u _k, then find out again k user u _kThe corresponding subcarrier of channel gain of maximum, suppose that the subcarrier of finding out is n subcarrier z _n, then work as N _k' 0 o'clock with n subcarrier z _nDistribute to k user u _k, then with n subcarrier _zN gathers Ω from subcarrier _NMiddle deletion is then upgraded original allocation to k user u _kNumber of sub carrier wave N _k'=N _k'-1, and upgrade k user u _kRate requirement R _k,

Afterwards with ρ _{K, n}Value be set to 1 and be used for n subcarrier of expression and be assigned to k user, work as N _k'=0 o'clock with k user from user's set omega _KMiddle deletion is returned step again and 2.-3 is continued to carry out, wherein, $R_k=R_k+\frac{B}{N}{\log }_2(1+{\mathrm{pH}}_{k,n})$ In "=" be assignment, $R_k=R_k+\frac{B}{N}{\log }_2(1+{\mathrm{pH}}_{k,n})$ In the R on "=" left side _kK user u after expression is upgraded _kRate requirement, "=" the right R _kFront k user u upgraded in expression _kRate requirement;

2.-5, distribute remaining subcarrier: with remaining N ^*Individual sub-allocation of carriers is given each user, and detailed process is: be this N ^*Individual subcarrier is found out respectively the user of relative channel gain maximum, for this N ^*N in the individual subcarrier ^*Individual subcarrier is supposed this n ^*Individual subcarrier is n subcarrier in N the subcarrier, and the user of the relative channel gain maximum found out of hypothesis is k user u _k, then with n subcarrier z _nDistribute to k user u _k, then upgrade the number of sub carrier wave N that the first beginning and end are assigned with ^*=N ^*-1, and upgrade k user u _kRate requirement R _k,

Again with ρ _{K, n}Value be set to 1 and be used for n subcarrier of expression and be assigned to k user, wherein, 1≤n ^*≤ N ^*, N ^*=N ^*"=" is assignment in-1,

In "=" be assignment,

In the R on "=" left side _kK user u after expression is upgraded _kRate requirement, "=" the right R _kFront k user u upgraded in expression _kRate requirement.

4. a kind of OFDMA resource allocation methods based on rate adaptation according to claim 3 is characterized in that distributing to during described step 3. the power P on k user's n the subcarrier _{K, n}Concrete acquisition process be:

3.-1, between K user, carry out power division, the gross power of distributing to k user is designated as P _{K, tot}, Wherein, 1≤k≤K, K represents total number of users, θ _kProportionality coefficient corresponding to rate requirement that represents k user preset, θ _iProportionality coefficient corresponding to rate requirement that represents i user, P _TotalRepresent total transmitted power;

3.-2, carry out power division at each subcarrier of distributing to each user, for k user, the subcarrier of supposing finally to distribute to it is the 1st subcarrier to the N _kIndividual subcarrier is then with this N _kThe power that distributes on n' the subcarrier in the individual subcarrier is designated as P _{K, n}',

Wherein, 1＜N _k＜N, 1≤n '≤N _k, N _kK user's number of sub carrier wave, H are finally distributed in expression _{Kn '}Represent that k user is at this N _kThe relative channel gain of correspondence on n' the subcarrier in the individual subcarrier, H _{K, i '}Represent that k user is at this N _kThe relative channel gain of correspondence on i' the subcarrier in the individual subcarrier.

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