CN103051583B - A kind of OFDMA resource allocation methods based on rate adaptation - Google Patents

Abstract

The invention discloses a method for allocating OFDMA resources based on rate self-adaptation. The method first allocates the number of sub-carriers among users, then allocates the number of sub-carriers, and finally allocates power. The advantage is that in the process of allocating the number of sub-carriers The preset rate requirements among users are allocated according to the corresponding proportional coefficients; in the subcarrier allocation process, the subcarriers are first allocated based on the ratio of the maximum minimum rate requirement to the corresponding proportional coefficients, and then the remaining subcarriers are allocated to the channel For the user with the largest gain, this subcarrier allocation method can improve the throughput of the system; in the process of power allocation, it is allocated in proportion based on the proportional coefficient corresponding to the user's rate requirement and the relative channel gain, which is not only easy to implement, but also computationally complex Low.

Description

A rate-adaptive OFDMA resource allocation method

technical field

The present invention relates to a resource allocation technology, in particular to an OFDMA resource allocation method based on rate self-adaptation.

Background technique

Multi-user Orthogonal Frequency Division Multiple Access (OFDMA, Orthogonal Frequency Division Multiple Access) is the preferred multiple access method for the physical layer of next-generation wireless communication. It is a wireless access method based on OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing) modulation method. It has the characteristics of high spectrum utilization, strong anti-fading ability, high transmission rate, flexible resource allocation, and simultaneous support for multiple users. It is considered to be the key technology of the next-generation broadband wireless access method. The OFDMA multiple access system divides the transmission bandwidth into a series of orthogonal non-overlapping subcarrier sets, assigns different subcarrier sets to different users to achieve multiple access, and can dynamically allocate the available bandwidth according to the channel state It is easy to optimize the utilization of system resources by allocating resources to users in need, so it is an important means to ensure user service quality, improve system capacity and spectrum utilization, and has become one of the hot spots of domestic and foreign scholars.

The problem of dynamic resource allocation can effectively utilize the diversity of users and improve the capacity of the system. In an OFDM system, according to different optimization objectives, resource allocation problems can generally be divided into two forms: one is the MA (Margin Adaptive) problem based on the minimization of transmit power, which is to make the total The transmit power is minimized; the other is the RA (RateAdaptive) problem based on rate maximization, which ensures that the capacity of the system is maximized under the condition that the total power is fixed. For the RA problem, it is divided into static resource allocation and dynamic resource allocation, wherein the static resource allocation is OFDM-TDMA (each user is assigned a set of predetermined time slots, and the user can use all subcarriers in a given time slot ) and OFDM-FDMA (each user is allocated a set of subcarriers of a predetermined continuous frequency band, and within each OFDM symbol, the user uses the assigned set of subcarriers); dynamic resource allocation, that is, each Users can use unfixed sub-carriers in different time slots, and the allocation is based on the instantaneous channel characteristics of each user in each sub-channel. At present, many typical dynamic OFDM adaptive resource allocation methods have been proposed, such as the fair resource allocation method based on the Max-Min (Max-Min) criterion, the resource allocation method based on proportional fairness, and the resource allocation method based on weight. In the Max-Min method, firstly, the total power is evenly allocated to each subcarrier, and then the method of maximizing the minimum user rate is used to maximize the system capacity and user fairness. Since this method is based on average power allocation, it does not consider to the time-varying nature of the channel, and thus is a suboptimal approach. In the proportional fair resource allocation method, Shen proposed a resource allocation scheme under the rate proportional constraints in the OFDMA system. First, the optimal sub-channel allocation was found based on the Max-Min method, and then the iterative search method was used to find out Optimal power allocation, however, this method performs a large number of iterative searches, and the computational complexity is high.

Contents of the invention

The technical problem to be solved by the present invention is to provide a rate-adaptive OFDMA resource allocation method that has low computational complexity, can maximize the transmission rate of the total transmission, and can meet the user's rate and fairness requirements.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a kind of OFDMA resource allocation method based on rate self-adaptation, it is characterized in that comprising the following steps:

① Determine the number of subcarriers initially allocated to each user according to the proportional coefficient corresponding to the preset rate requirement of each user, and record the number of subcarriers initially allocated to the kth user as N _k ', and then according to the initial allocation to The number of sub-carriers of K users, calculate the number of sub-carriers that are not allocated initially, denoted as N ^* , Among them, 1≤k≤K, K represents the total number of users, and N represents the total number of subcarriers;

②According to the number of subcarriers initially assigned to each user, allocate the subcarriers that should be allocated to each user. During the allocation process, the user with the smallest ratio of the rate requirement to the corresponding proportional coefficient is always given priority to allocate the highest relative channel gain. Good subcarriers, until the number of subcarriers that should be initially assigned to all users is satisfied; then allocate the remaining subcarriers to users with the largest relative channel gain;

③ Perform power allocation on each subcarrier allocated to each user, and denote the power on the nth subcarrier allocated to the kth user as P _k,n .

The determination process of the number of subcarriers N _k ' initially allocated to the kth user in the step ① is as follows: assuming that the proportional coefficient corresponding to the preset rate requirement of the kth user is θ _k , then calculate the initial allocation according to θ _k the number of subcarriers N _k ' for the kth user, Among them, _θi represents the proportional coefficient corresponding to the rate requirement of the i-th user, is the rounding down symbol.

The concrete process of described step 2. is:

②-1. Initialize the rate requirement of each user to 0, record the subcarrier set as Ω _N , Ω _N ={z ₁ ,z ₂ ,…,z _n ,…,z _N }, and record the user set as Ω _K , Ω _K ＝{u ₁ ,u ₂ ,…,u _k ,…,u _K }, record the average power as p, The weighting factor of whether the nth subcarrier corresponding to the kth user is allocated is recorded as ρk _,n , ρk _,n =1 means that the nth subcarrier corresponding to the kth user has been allocated, ρk _{, n} = 0 means that the nth subcarrier corresponding to the kth user is not allocated, where 1≤n≤N, z ₁ means the first subcarrier, z ₂ means the second subcarrier, z _n means the nth subcarrier , z _N represents the Nth subcarrier, u ₁ represents the first user, u ₂ represents the second user, u _k represents the kth user, u _K represents the Kth user, and P _total represents the total transmission power;

②-2. Initially allocate a subcarrier with the best relative channel gain to each user, then delete the allocated subcarrier from the subcarrier set Ω _N , and then update the number of subcarriers initially allocated to each user and each The rate requirement of each user; for the kth user u _k , find the subcarrier corresponding to the maximum channel gain, assuming that the found subcarrier is the nth subcarrier z _n , then allocate the nth subcarrier z _n to The kth user u _k , then delete the nth subcarrier z _n from the subcarrier set Ω _N , then update the number of subcarriers N _k '=N _k '-1 initially assigned to the kth user u _k , and The rate requirement for updating the kth user u _k is R _k , Then set the value of ρ _k,n to 1 to indicate that the nth subcarrier is allocated to the _kth user, where "=" in Nk'= _Nk' -1 is the assignment symbol, and B represents the channel bandwidth, H _k,n represents the relative channel gain of the kth user u _k on the nth subcarrier z _n , H _k,n = |h _k,n | ² /δ ² , h _k,n represents the kth user u The impulse response of _k on the nth subcarrier z _n , δ ² represents the variance of additive Gaussian white noise, and "||" is the symbol for taking the absolute value;

②-3. Judging whether ||Ω _N ||>N ^* is true, if true, execute step ②-4, otherwise, execute step ②-5, where ||Ω _N || means after deleting the allocated subcarriers The number of subcarriers in the subcarrier set Ω _N of ;

②-4. Allocate the subcarriers that should be allocated: continue to allocate the unallocated subcarriers among the subcarriers that should be allocated to each user, and first find out the ratio between the rate requirement and the corresponding proportional coefficient in the allocation process The smallest user, assuming that the found user is the kth user u _k , then find out the subcarrier corresponding to the maximum channel gain of the kth user u _k , assuming that the found subcarrier is the nth subcarrier z _n , then when N _k '>0, assign the nth subcarrier z _n to the kth user u _k , then delete the nth subcarrier z _n from the subcarrier set Ω _N , and then update the initial assignment to the kth user The number of subcarriers N _k '=N _k '-1 of the user u _k , and update the rate requirement R _k of the kth user u _k , Afterwards, set the value of ρ _k,n to 1 to indicate that the nth subcarrier is allocated to the kth user, and when N _k '=0, delete k users from the user set Ω _K , and then return to step ②- 3 continue to execute, where, $R_k=R_k+\frac{B}{N}{\log }_2(1+{\mathrm{pH}}_{k,\mathrm{no}})$ "=" is the assignment symbol, $R_k=R_k+\frac{B}{N}{\log }_2(1+{\mathrm{pH}}_{k,\mathrm{no}})$ The R _k on the left side of "=" represents the rate requirement of the kth user u _k after the update, and the R _k on the right side of "=" represents the rate requirement of the kth user u _k before the update;

②-5. Assign the remaining subcarriers: assign the remaining N ^* subcarriers to each user. The specific process is: find out the user with the largest relative channel gain for the N ^* subcarriers respectively. For the N ^* subcarriers In the n ^* th subcarrier, assuming that the n ^* th subcarrier is the nth subcarrier in the N subcarriers, and assuming that the user with the largest relative channel gain found is the kth user u _k , then the nth subcarrier The carrier z _{n is} allocated to the kth user u _k , and then the initial unallocated subcarrier number N ^* = N ^* -1 is updated, and the rate requirement R _k of the kth user u _k is updated, Then set the value of ρ _k,n to 1 to indicate that the nth subcarrier is allocated to the kth user, where, 1≤n ^* ≤N ^* , N ^* =N ^* -1, "=" is the assignment symbol , "=" is the assignment symbol, The R _k on the left side of "=" in the figure represents the rate requirement of the kth user u _k after the update, and the R _k on the right side of "=" represents the rate requirement of the kth user u _k before the update.

The specific acquisition process of the power P _k on the nth subcarrier assigned to the kth user in the step 3., n is:

③-1. Perform power allocation among K users, and record the total power allocated to the kth user as P _k,tot , Among them, 1≤k≤K, K represents the total number of users, θ _k represents the proportional coefficient corresponding to the preset rate requirement of the kth user, θ _i represents the proportional coefficient corresponding to the rate requirement of the i-th user, and P _total represents the total transmit power;

③-2. Perform power allocation on each subcarrier allocated to each user. For the kth user, assuming that the subcarriers finally allocated to it are from the 1st subcarrier to the N _kth subcarrier, then the N _k The power allocated on the n'th subcarrier among subcarriers is denoted as P _k,n' , Among them, 1<N _k <N, 1≤n'≤N _k , N _k represents the number of subcarriers finally allocated to the kth user, H _k,n' represents the number of subcarriers of the kth user in the N _k subcarriers The relative channel gain corresponding to the n'th subcarrier, H _k,i' represents the relative channel gain corresponding to the kth user on the i'th subcarrier among the N _k subcarriers.

Compared with the prior art, the present invention has the advantages that: in the subcarrier number allocation process, it is allocated based on the proportional coefficient corresponding to the preset rate requirement among users; It is required to allocate subcarriers according to the ratio of the corresponding proportional coefficient, and then allocate the remaining subcarriers to users with the largest channel gain. This subcarrier allocation method can improve the throughput of the system; in the power allocation process, it is based on the user's rate It is required that the corresponding proportional coefficients and relative channel gains be distributed proportionally, which is not only easy to implement, but also has low computational complexity.

Description of drawings

Fig. 1 is the schematic diagram that adopts TDMA method, Shen method and the method of the present invention to carry out resource allocation and obtain all user total capacity changes with the number of users;

Fig. 2 is the schematic diagram that adopts TDMA method, Shen method and the method of the present invention to carry out resource allocation and obtain the user fairness factor FP that changes with the number of users;

Fig. 3 is a schematic diagram showing the change of execution time of resource allocation with the number of users under the same channel conditions by using the Shen method and the method of the present invention.

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

The goal of a rate-adaptive-based OFDMA resource allocation method proposed by the present invention is to maximize the total transmission rate while satisfying the rate requirements and fairness requirements of each user, which is an OFDMA optimal resource allocation model based on the downlink On the basis of , the optimal resource allocation model is as follows: Among them, K represents the total number of users, N represents the total number of subcarriers, ρ _{k, n} is used to represent the weighting factor of whether the nth subcarrier is allocated to the kth user, if the nth subcarrier is allocated to For the k-th user, then ρ _k,n =1, if the n-th subcarrier is not allocated to the k-th user, then ρ _k,n =0, B represents the channel bandwidth, p _k,n represents the k-th user in The transmit power on the nth subcarrier, H _k,n represents the relative channel gain of the kth user on the nth subcarrier, H _k,n = |h _k,n | ² /δ ² , h _k,n represents The impulse response of the kth user on the nth subcarrier, δ ² represents the variance of additive white Gaussian noise, "||" is the symbol for taking the absolute value, P _total represents the total transmission power, and R ₁ represents the first user’s Rate requirement, R ₂ indicates the rate requirement of the second user, R _K indicates the rate requirement of the K-th user, θ ₁ indicates the proportional coefficient corresponding to the rate requirement of the first user, and θ ₂ indicates the rate requirement of the second user The corresponding proportional coefficient, θ _K represents the proportional coefficient corresponding to the rate requirement of the Kth user, the constraint condition (a) means that the sum of the transmit power of all users on all subcarriers cannot exceed the total transmit power, and the constraint condition (b) Indicates that the transmit power of each user on each subcarrier should be greater than or equal to 0, constraint (c) indicates whether the nth subcarrier is allocated to the kth user, constraint (d) indicates that each subcarrier is only for one user Using, the constraint condition (e) is the scale factor value set to ensure the fairness of the user.

In order to measure the fairness of users under different conditions, the fairness factor is defined here, denoted as FP, Among them, R _k represents the rate requirement of the kth user, θ _k represents the proportional coefficient corresponding to the rate requirement of the kth user, from It can be seen that FP≤1, the closer FP is to 1, the better the fairness is, and the fairness can be satisfied to the maximum when FP=1.

The inventive method specifically comprises the following steps:

① Determine the number of subcarriers initially allocated to each user according to the proportional coefficient corresponding to the preset rate requirement of each user, and record the number of subcarriers initially allocated to the kth user as N _k ', and then according to the initial allocation to The number of sub-carriers of K users, calculate the number of sub-carriers that are not allocated initially, denoted as N ^* , Wherein, 1≤k≤K, K represents the total number of users, and N represents the total number of subcarriers.

In this specific embodiment, the determination process of the number of subcarriers N _k ' initially allocated to the kth user in step ① is as follows: assuming that the proportional coefficient corresponding to the preset rate requirement of the kth user is θ _k , then according to θ _k Calculate the number of subcarriers N _k ' initially assigned to the kth user, Among them, _θi represents the proportional coefficient corresponding to the rate requirement of the i-th user, is the rounding down symbol.

②According to the number of subcarriers initially assigned to each user, allocate the subcarriers that should be allocated to each user. During the allocation process, the user with the smallest ratio of the rate requirement to the corresponding proportional coefficient is always given priority to allocate the highest relative channel gain. Good subcarriers are used until the number of subcarriers that should be initially assigned to all users is satisfied; then the remaining subcarriers are allocated to users with the largest relative channel gain.

In this specific embodiment, the concrete process of step 2. is:

②-1. Initialize the rate requirement of each user to 0, record the subcarrier set as Ω _N , Ω _N ={z ₁ ,z ₂ ,…,z _n ,…,z _N }, and record the user set as Ω _K , Ω _K ＝{u ₁ ,u ₂ ,…,u _k ,…,u _K }, record the average power as p, The weighting factor of whether the nth subcarrier corresponding to the kth user is allocated is recorded as ρk _,n , ρk _,n =1 means that the nth subcarrier corresponding to the kth user has been allocated, ρk _{, n} = 0 means that the nth subcarrier corresponding to the kth user is not allocated, where 1≤n≤N, z ₁ means the first subcarrier, z ₂ means the second subcarrier, z _n means the nth subcarrier , z _N represents the Nth subcarrier, u ₁ represents the first user, u ₂ represents the second user, u _k represents the kth user, u _K represents the Kth user, and P _total represents the total transmission power.

②-2. Initially allocate a subcarrier with the best relative channel gain to each user, then delete the allocated subcarrier from the subcarrier set Ω _N , and then update the number of subcarriers initially allocated to each user and each The rate requirement of each user; for the kth user u _k , find the subcarrier corresponding to the maximum channel gain, assuming that the found subcarrier is the nth subcarrier z _n , then allocate the nth subcarrier z _n to The kth user u _k , then delete the nth subcarrier z _n from the subcarrier set Ω _N , then update the number of subcarriers N _k '=N _k '-1 initially assigned to the kth user u _k , and The rate requirement for updating the kth user u _k is R _k , Then set the value of ρ _k,n to 1 to indicate that the nth subcarrier is allocated to the _kth user, where "=" in Nk'= _Nk' -1 is the assignment symbol, and B represents the channel bandwidth, H _k,n represents the relative channel gain of the kth user u _k on the nth subcarrier z _n , H _k,n = |h _k,n | ² /δ ² , h _k,n represents the kth user u The impulse response of _k on the nth subcarrier z _n , δ ² represents the variance of additive Gaussian white noise, and "||" is the symbol for taking the absolute value.

②-3. Judging whether ||Ω _N ||>N ^* is true, if true, execute step ②-4, otherwise, execute step ②-5, where ||Ω _N || means after deleting the allocated subcarriers The number of subcarriers in the subcarrier set Ω _N of .

②-4. Allocate the subcarriers that should be allocated: continue to allocate the unallocated subcarriers among the subcarriers that should be allocated to each user, and first find out the ratio between the rate requirement and the corresponding proportional coefficient in the allocation process The smallest user, assuming that the found user is the kth user u _k , then find out the subcarrier corresponding to the maximum channel gain of the kth user u _k , assuming that the found subcarrier is the nth subcarrier z _n , then when N _k '>0, assign the nth subcarrier z _n to the kth user u _k , then delete the nth subcarrier z _n from the subcarrier set Ω _N , and then update the initial assignment to the kth user The number of subcarriers N _k '=N _k '-1 of the user u _k , and update the rate requirement R _k of the kth user u _k , Afterwards, set the value of ρ _k,n to 1 to indicate that the nth subcarrier is allocated to the kth user, and when N _k '=0, delete k users from the user set Ω _K , and then return to step ②- 3 continue to execute, where, $R_k=R_k+\frac{B}{N}{\log }_2(1+{\mathrm{pH}}_{k,\mathrm{no}})$ "=" is the assignment symbol, $R_k=R_k+\frac{B}{N}{\log }_2(1+{\mathrm{pH}}_{k,\mathrm{no}})$ The R _k on the left of "=" in the figure represents the rate requirement of the k-th user uk after the update, and the R _k on the right of "=" represents the rate requirement of the _k -th user _uk before the update.

②-5. Allocate the remaining subcarriers: allocate the remaining N ^* subcarriers to each user. The allocation criterion is: allocate the subcarriers with the largest relative channel gain to the users. The specific process is: for the N ^* subcarriers Carriers respectively find the user with the largest relative channel gain. For the n ^* th subcarrier in the N ^* th subcarriers, assume that the n ^* th subcarrier is the nth subcarrier in the N subcarriers, and assume that the found relative channel The user with the largest gain is the kth user u _k , then assign the nth subcarrier z _n to the kth user u _k , then update the initial number of unallocated subcarriers N ^* = N ^* -1, and update the The rate requirement R _k for k users u _k , Then set the value of ρ _k,n to 1 to indicate that the nth subcarrier is allocated to the kth user, where, 1≤n ^* ≤N ^* , N ^* =N ^* -1, "=" is the assignment symbol , "=" is the assignment symbol, The R _k on the left side of "=" in the figure represents the rate requirement of the kth user u _k after the update, and the R _k on the right side of "=" represents the rate requirement of the kth user u _k before the update.

③ Perform power allocation on each subcarrier allocated to each user, and denote the power on the nth subcarrier allocated to the kth user as P _k,n .

In this specific embodiment, the specific acquisition process of the power P _k on the nth subcarrier allocated to the kth user in step ③ is:

③-1. Perform power allocation among K users, and record the total power allocated to the kth user as P _k,tot , Among them, 1≤k≤K, K represents the total number of users, θ _k represents the proportional coefficient corresponding to the preset rate requirement of the kth user, θ _i represents the proportional coefficient corresponding to the rate requirement of the i-th user, and P _total represents the total transmit power.

③-2. Perform power allocation on each subcarrier allocated to each user. For the kth user, assuming that the subcarriers finally allocated to it are from the 1st subcarrier to the N _kth subcarrier, then the N _k The power allocated on the n'th subcarrier among subcarriers is denoted as P _k,n' , Among them, 1<N _k <N, 1≤n'≤N _k , N _k represents the number of subcarriers finally allocated to the kth user, H _k,n' represents the number of subcarriers of the kth user in the N _k subcarriers The relative channel gain corresponding to the n'th subcarrier, H _k,i' represents the relative channel gain corresponding to the kth user on the i'th subcarrier among the N _k subcarriers.

The effectiveness and feasibility of the method of the present invention are illustrated below by experiments.

Here, the simulation environment used is a 6-path frequency selective Raleigh channel, the maximum Doppler frequency shift is 30HZ, the delay spread is 5μs, the total number of subcarriers is 64, the system bandwidth is 1MHz, and the total transmission power is 1W , the Gaussian white noise power spectral density is N ₀ =10 ^-8 , the number of users is 2 to 10, and the number of Monte Carlo simulations is 2000 times. The validity and feasibility of the method of the present invention are analyzed from three aspects of system capacity, user fairness factor and execution time.

Fig. 1 has provided the schematic diagram that adopts TDMA method, Shen method and the method of the present invention to carry out resource allocation (subcarrier, bit and power) and obtains the schematic diagram that the total capacity of all users changes with the number of users, as can be seen from Fig. increase, the system capacity obtained by the method of the present invention and the Shen method increases accordingly, while the system capacity obtained by the TDMA method remains basically unchanged. This is because the method of the present invention and the Shen method are dynamic adaptive resource allocation methods that utilize multi-user The diversity principle of the present invention is superior to the static TDMA resource allocation method, and the system capacity of the method of the present invention is obviously higher than that of the Shen method with the increase of users.

Fig. 2 has provided the schematic diagram that adopts TDMA method, Shen method and the method of the present invention to carry out resource allocation and obtains the schematic diagram that the fairness factor FP of system user changes with the number of users, as can be seen from Fig. 2 along with the increase of the number of users, Shen method embodies User fairness is ensured, and its fairness factor is close to 1. The fairness factors obtained by the method of the present invention and the TDMA method all show a downward trend. This is because the Shen method maximizes the system capacity while taking into account the fairness of users. The method of the invention maximizes the system capacity while slightly reducing user fairness. Compared with the TDMA method, the method of the invention has better fairness, and its fairness factor is 0.88-0.98.

Fig. 3 has provided the schematic diagram that adopts Shen method and the method of the present invention to carry out resource allocation under the same channel condition and the schematic diagram that the execution time changes with the number of users, as can be seen from Fig. 3 along with the increase of the number of users, the method of the present invention progresses The time required for resource allocation increases slightly, while the time required for the Shen method shows an increasing trend. This is because the power allocation in the method of the present invention is allocated proportionally based on the user's rate ratio coefficient and relative channel gain, which has a very low complexity. The degree is easy to implement, while the Shen method uses an iterative search method to find the optimal power allocation, and performs a large number of iterative searches, which requires high computational complexity.

Claims (3)

1., based on an OFDMA resource allocation methods for rate adaptation, it is characterized in that comprising the following steps:

1. corresponding according to the rate requirement of each user preset proportionality coefficient, determines the number of sub carrier wave being initially allocated to each user, and the number of sub carrier wave being initially allocated to a kth user is designated as N _k', then according to the number of sub carrier wave being initially allocated to K user, the number of sub carrier wave that the calculating first beginning and end are assigned with, is designated as N ^*, wherein, 1≤k≤K, K represents total number of users, and N represents total number of sub-carriers;

2. according to the number of sub carrier wave being initially allocated to each user, for each user distributes the subcarrier that should be assigned with, distribute relative channel gain best subcarrier, until the number of sub carrier wave that all users initially should be assigned with is met always preferentially in the assignment procedure the rate requirement user minimum with the ratio of corresponding proportionality coefficient; Then by remaining sub carries allocation to the maximum user of relative channel gain;

Described step detailed process is 2.:

-1 2., the rate requirement of each user is initialized as 0, t easet ofasubcarriers 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 the n-th subcarrier corresponding to a kth user is assigned with is designated as ρ _k,n, ρ _k,n=1 represents that the n-th subcarrier corresponding to a kth user is assigned with, ρ _k,n=0 represents that the n-th subcarrier corresponding to a kth user is not assigned with, wherein, and 1≤n≤N, z ₁represent the 1st subcarrier, z ₂represent the 2nd subcarrier, z _nrepresent the n-th subcarrier, z _nrepresent N number of subcarrier, u ₁represent the 1st user, u ₂represent the 2nd user, u _krepresent a kth user, u _krepresent K user, P _totalrepresent total transmitted power;

-2 2., initially distribute a best subcarrier of relative channel gain to each user, then by the subcarrier that distributed from t easet ofasubcarriers Ω _nmiddle deletion, then renewal is initially allocated to the number of sub carrier wave of each user and the rate requirement of each user; For a kth user u _k, find out the subcarrier corresponding to maximum channel gain, suppose that the subcarrier found out is the n-th subcarrier z _n, then by the n-th subcarrier z _ndistribute to a kth user u _k, then by the n-th subcarrier z _nfrom t easet ofasubcarriers Ω _nmiddle deletion, then upgrades and is initially allocated to a kth user u _knumber of sub carrier wave N _k'=N _k'-1, and upgrade a kth user u _krate requirement R _k, again by ρ _k,nvalue be set to 1 for representing that the n-th subcarrier is assigned to a kth user, wherein, N _k'=N _kin '-1, "=" is assignment, and B represents channel width, H _k,nrepresent a kth user u _kat the n-th subcarrier z _non relative channel gain, H _k,n=| h _k,n| ²/ δ ², h _k,nrepresent a kth user u _kat the n-th subcarrier z _non impulse response, δ ²represent 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 perform step 2.-4, otherwise, perform step 2.-5, wherein, || Ω _n|| represent the t easet ofasubcarriers Ω after deleting allocation of subcarriers _nin the number of subcarrier;

2. the subcarrier that should be assigned with-4, is distributed: the subcarrier be not also assigned with in the subcarrier that should be assigned with continues to distribute to each user, first find out the rate requirement user minimum with the ratio of corresponding proportionality coefficient in the assignment procedure, suppose that the user found out is a kth user u _k, then a kth user u is found out again _kthe subcarrier corresponding to maximum channel gain, suppose that the subcarrier found out is the n-th subcarrier z _n, then N is worked as _k' >0 time by the n-th subcarrier z _ndistribute to a kth user u _k, then by the n-th subcarrier z _nfrom t easet ofasubcarriers Ω _nmiddle deletion, then upgrades and is initially allocated to a kth user u _knumber of sub carrier wave N _k'=N _k'-1, and upgrade a kth user u _krate requirement R _k, afterwards by ρ _k,nvalue be set to 1 for representing that the n-th subcarrier is assigned to a kth user, work as N _kduring '=0 by k user from user's set omega _kmiddle deletion, then return step 2.-3 continuation execution, 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 _krepresent a kth user u after upgrading _krate requirement, "=" the right R _krepresent a kth user u before upgrading _krate requirement;

2.-5, remaining subcarrier is distributed: by remaining N ^*individual sub carries allocation gives each user, and detailed process is: be this N ^*individual subcarrier finds out the maximum user of relative channel gain respectively, for this N ^*in individual subcarrier n-th ^*individual subcarrier, suppose this n-th ^*individual subcarrier is the n-th subcarrier in N number of subcarrier, and supposes that the maximum user of the relative channel gain found out is a kth user u _k, then by the n-th subcarrier z _ndistribute to a kth user u _k, the number of sub carrier wave N that the beginning and end at the beginning of then upgrading are assigned with ^*=N ^*-1, and upgrade a kth user u _krate requirement R _k, again by ρ _k,nvalue be set to 1 for representing that the n-th subcarrier is assigned to a kth user, wherein, 1≤n ^*≤ N ^*, N ^*=N ^*in-1, "=" is assignment, in "=" be assignment, in the R on "=" left side _krepresent a kth user u after upgrading _krate requirement, "=" the right R _krepresent a kth user u before upgrading _krate requirement;

3. on each subcarrier distributing to each user, carry out power division, the power distributed on n-th subcarrier of a kth user 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 the number of sub carrier wave N being initially allocated to a kth user during described step 1. _k' deterministic process be: suppose that proportionality coefficient corresponding to the rate requirement of a kth user preset is θ _k, then according to θ _kcalculate the number of sub carrier wave N being initially allocated to a kth user _k', wherein, θ _irepresent the proportionality coefficient that the rate requirement of i-th user is corresponding, for rounding symbol downwards.

3. a kind of OFDMA resource allocation methods based on rate adaptation according to claim 1, is characterized in that the power P distributed to during described step 3. on n-th subcarrier of a kth user _k,nconcrete acquisition process be:

-1 3., between K user, carry out power division, the gross power distributing to a kth user is designated as P _{k, tot}, wherein, 1≤k≤K, K represents total number of users, θ _krepresent the proportionality coefficient that the rate requirement of a kth user preset is corresponding, θ _irepresent the proportionality coefficient that the rate requirement of i-th user is corresponding, P _totalrepresent total transmitted power;

-2 3., on each subcarrier distributing to each user, carry out power division, for a kth user, the subcarrier supposing finally to distribute to it is that the 1st subcarrier is to N _kindividual subcarrier, then by this N _kin individual subcarrier n-th ' power that individual subcarrier distributes is designated as P _{k, n'}, wherein, 1<N _k<N, 1≤n'≤N _k, N _krepresent the number of sub carrier wave finally distributing to a kth user, H _{k, n'}represent that a kth user is at this N _kin individual subcarrier n-th ' relative channel gain corresponding on individual subcarrier, H _{k, i'}represent that a kth user is at this N _kin individual subcarrier i-th ' relative channel gain corresponding on individual subcarrier.