CN1829210A - Method for distributing carrier wave with equitable proportion in multi user OFDM system - Google Patents

Abstract

The present invention relates to a dynamical carrier wave distribution method having user fairness in multi-user single/multiple aerial quadrature frequency division multiple addresses (OFDMA) system. OFDMA, being used as next generation wireless multimedia network transmission technique, is presently adopted by IEEE 802.16 standard. Compared With general TDMA, said OFDMA can dynamically distribute carrier wave. But general OFDMA carrier wave distribution method does not consider fairness between users, therefore present invention provides an effective dynamical carrier wave distribution method. It contains first to proceed initializing distribution to all carrier wave based on speed rate among user, then according to principle of distributing maximum channel noise ratio carrier wave to user with lowest speed rate, to proceed redistribution to primary distributed to user carrier wave, to ensure fairness among users.Said method has user fairness and raising system capacity advantages.

Description

The carrier allocation method of equitable proportion in the multi-user OFDM system

Technical field

The present invention relates to the dynamic allocation method of carrier wave (frequency resource) in multi-user's list/many antennas ofdm system.

Background technology

Along with the fusion gradually of wireless network, multimedia technology and internet, people are more and more higher to the requirement of the type of radio communication service and quality.For satisfying the requirement of radio multimedium and high speed data transfers, need the Development of New Generation wireless communication system.In the new generation of wireless system, to network layer, will extensively adopt some new technologies, as OFDM (OFDM), many antennas input and output (MTMO) etc. from physical layer, media access control layer.

OFDM is divided into many orthogonal sub-channels to channel at frequency domain, and whole wideband frequency selective channel is divided into the subchannel of relatively flat, simultaneously, inserts Cyclic Prefix (CP) as protection at interval at each OFDM intersymbol, has reduced intersymbol interference (ISI) greatly.Because OFDM has advantages such as ability of anti-multipath is strong, generally believes that it is the key technology of new generation of wireless transmission link.

The MTMO system is meant and is sending and receiving terminal use multi-antenna array that it can significantly improve power system capacity (spectrum efficiency) and wireless transmission link quality (bit error rate).The mode of utilizing the MIMO technology to improve power system capacity and transmission quality comprises two classes: space division multiplexing (SM) and space diversity (SD).The MIMO OFDM transmission technology that combines with OFDM as the MIMO that proposes towards the new generation of wireless information network also is subjected to extensive concern.The MIMO OFDM technology that MIMO combines with OFDM has both advantages, it both resolved into one group of parallel flat fading channel to frequency selectivity MTMO fading channel by the OFDM modulation, utilize MIMO to improve power system capacity again, be applicable to the multimedia service of high quality.

As everyone knows, the wireless system of practicability must be supported multi-user communication.Therefore, no matter be general ofdm system, still the ofdm system of many antennas all need have the ability of supporting that the multi-user inserts.Multi-user OFDM allows a plurality of users to share an OFDM symbol.Existing fixed channel allocation mode, all can be used for multi-user OFDM system as time division multiple access (TDMA), frequency division multiple access (FDMA), code division multiple access (CDMA) and space division multiple access (SDMA), they distribute resources such as different time slots, frequency, sign indicating number to give each user respectively.These methods of salary distribution belong to static allocation, do not consider the influence that wireless channel changes.

FDMA is applied to OFDM and is called OFDM (OFDMA), and it is in each OFDM symbol, for each user distributes a part of subcarrier in all carrier waves.When unknown each user's of transmitter channel condition information (CSI), can be that each user distributes one group of subcarrier arbitrarily.And when the channel response of transmitter known users, transmitting terminal is given the user according to channel condition information self adaptation allocation of subcarriers, obtains any allocation of subcarriers more performance of each user of comparison.When OFDMA is applied to when up, all insert that users can work and are user's dynamic bandwidth allocation under low-power amplifier.When it is applied to when descending, to the parallel emission of a plurality of users data, can be by adjusting subcarrier down transmitting power control link-quality.Compare with TDMA, the OFDMA advantage is dynamic distributing carrier wave, paired pulses noise and disturb very strong robustness is arranged.

Simultaneously, the characteristics of multi-user wireless network are, there are a plurality of users can receive the signal of transmitting terminal simultaneously, therefore, transmitter is that different user has been set up different propagation channels, then can utilize the wireless channel time varying characteristic, give the best user of channel condition allocation of radio resources, this method of the different fading channel feature of each user of utilizing is called multi-user diversity (MuD).MuD can follow the tracks of the small scale time-varying characteristics that utilize channel, improves the utilance of Radio Resource (time, frequency, code, space etc.).

When obtaining multi-user diversity gain, also must the assurance system in each user can obtain capacity liberally.Among the OFDMA, general carrier allocation method is not considered the fairness problem between the user, therefore, need propose effective Dynamic Resource Allocation for Multimedia algorithm at the time variation and the user fairness characteristics of wireless channel.

The list of references tabulation:

[1] G.J.Foschini, M.J.Gans is published in Wireless PersonalCommunications, the article that is entitled as " On limits ofwireless communications in fading environment when usingmultiple antennas " on 19986 (3) the 311st～315 pages.

[2] V.Tarokh, N.Scshadri, A.R.Calderband is published in IEEE Trans.On IT, the article that is entitled as " Space-time codes for highdata rate wireless communication:Performance critierion andcode construction " on 199844 (2) the 744th～765 pages.

[3] E.Lawrey is published in the article that is entitled as " Multiuser OFDM " on the 761st～764 page of the Proc.International Symposium onSignal Processing and its Applications.

Summary of the invention

The object of the present invention is to provide the dynamic carrier with user fairness (frequency resource) distribution method in a kind of multi-user OFDM system.

Among the present invention, total K the user of supposing the system and N carrier wave, each allocation of carriers equal-wattage and can only be by user's utilization.Therefore, can make to give a definition:

(A) the interchannel noise ratio of n the carrier wave of user k is $H_{k,n}=\frac{h_{k,n}^2}{N_{0}B/N},$ H wherein _{K, n}Be the channel gain of n the carrier wave of user k, N ₀Be the white Gauss noise power spectral density, B is a channel width, noise power σ ²=N ₀B/N.If distributing to the power of n the carrier wave of user k is p _{K, n}, then this user's received signal noise ratio is SNR _{K, n}=p _{K, n}H _{K, n}, p _{K, n}Satisfy total power constraint $\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{p}_{k,n}\≤P_{\mathrm{tot}}.$

(B) speed of n the carrier wave of user k is r _{K, n}=log ₂(1+SNR _{K, n}), the capacity of user k (spectrum efficiency) is $C_k=\stackrel{N_k}{\underset{n=1}{\mathrm{\Σ}}}\frac{1}{N_k}{\mathrm{\ρ}}_{k,n}{r}_{k,n},$ Speed is $R_k=\underset{n=1}{\overset{N_k}{\mathrm{\Σ}}}\frac{B}{N_k}{\mathrm{\ρ}}_{k,n}{r}_{k,n},$ N wherein _kFor distributing to the carrier number of user k, ρ _{K, n}∈ [0,1] represents that its value is 1 or 0 only, depends on whether carrier wave n is assigned to user k, if carrier wave n is assigned to user k, then ρ _{K, n}=1, otherwise ρ _{K, n}=0; All users' traversal total capacity (Ergodic sum capacity) is

$C=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{C}_k.$

(C) for guaranteeing the fairness between the user, according to user's mean data rate, the ratio that limits each user rate is R ₁: R ₂: ...: R _K=φ ₁: φ ₂: ...: φ _K

(D) the ratio speed of definition user k is R _k/ φ _k

The thought of carrier allocation method of the present invention is to give the user allocation of carriers of peaked channal noise ratio as far as possible.At first, all carrier waves of comparison according to the speed between each user carry out the initialization distribution; Then, according to the principle of the allocation of carriers of peaked channal noise ratio being given minimum ratio rate users, reallocate for user's carrier wave to initial allocation.Its step is as follows:

The first step: initial carrier allocation.

Determine to distribute to each user's carrier number N according to the ratio of the speed between each user _kEven, N ₁: N ₂: ...: N _K=φ ₁: φ ₂: ...: φ _K, obtain distributing to the carrier number of user k thus Round under the expression).For unappropriated carrier wave $N^{*}=N-\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{N}_k,$ By handling these allocation of carriers for the user of higher channel noise ratio, distribute a carrier wave to give the user of high channel noise ratio earlier, the carrier wave of reallocate is given the user of time high channel noise ratio, by that analogy, and particularly, several steps below dividing.

(1) determines to distribute to each user's carrier number according to the ratio of the speed between each user;

(2) deduct the carrier wave that the carrier wave of distributing to each user is not assigned with total carrier number;

(3) initialization, carrier wave counting n=1;

(4) calculate each subscriber channel noise ratio of this carrier wave correspondence, by relatively obtaining and the user of high channel noise ratio;

(5) this allocation of carriers is given the user of high channel noise ratio;

(6) more be newly assigned to this user's carrier number N _k=N _k+ 1;

(7) upgrade carrier wave counting n=n+1;

(8) judge, if n is not more than N ^*, change (4) step iteration, till the carrier wave that will not be assigned with is all distributed to the user; Otherwise, carry out following each step.

Second step: carrier reallocation.

Divide following several steps to finish.

(1) initialization:

For user k ∈ [1, K] arbitrarily, and carrier wave n ∈ [1, N-N ^*], user k is not given in definition

The carrier wave n of distributing is ρ _{K, n}=0;

For user k ∈ [1, K] arbitrarily, the speed R of user k _{K, n}=0;

Carrier set N=[1 2 ... N-N ^*].

(2) distribute the carrier wave of its peaked channal noise ratio to determine each user rate R to each user _kInitial value:

1) initialization, user number counting k=1;

2) calculate each carrier channel noise ratio of this user's correspondence, by relatively obtaining the carrier wave of high channel noise ratio;

3) give user k this allocation of carriers;

4) upgrade carrier set, promptly concentrate to deduct the carrier number N that has distributed from total carrier wave _k=N _k-1, N=N-{n};

5) the speed R in the redetermination (B) more _k

6) upgrade user number counting k=k+1

7) judge,, change 2 over to if k is not more than K) the step iteration; Otherwise, carry out following each step.

(3) user's distributing carrier wave of giving minimum ratio speed is to guarantee the subscribers carrier distributional equity:

8) find the user k of minimum scale speed;

9) find the peaked channal noise of user k to compare carrier wave n;

10) in this time slot, distribute n carrier wave to give user k;

11) upgrade carrier set N _k=N _k-1, N=N-{n};

12) the speed R in the redetermination (B) more _k

13) judge,, change 8 if N=is not null set) the step iteration, otherwise, finish.

Above-mentioned is the carrier allocation method of single antenna ofdm system.Many antennas OFDM (MIMO OFDM) system for the space division multiplexing mode of operation, after receiving terminal utilizes feedback channel that channel condition information is returned to transmitting terminal, channel matrix is carried out characteristic value (SVD) decompose and to resolve into the single output of a plurality of single inputs of parallel independent (SISO) channel to mimo channel.Like this, can be applied to the carrier allocation method of aforementioned single antenna ofdm system in many antennas ofdm system.Notice that in SISO OFDM the subcarrier of distributing to the user is used for a width of cloth antenna, and among the MIMO OFDM, the subcarrier of distributing to the user is used for several antennas.If transmission, reception antenna number equate, and the identical carrier wave of every width of cloth antenna assignment, the carrier number of then every width of cloth antenna assignment is to distribute to this user's the carrier number and the ratio of antenna number.

Description of drawings

Below, with reference to the accompanying drawings, the preferred embodiments of the present invention are described in detail, wherein:

Fig. 1 shows multi-user's single antenna ofdm system;

Fig. 2 (a) shows the overview flow chart according to the carrier allocation method of the embodiment of the invention;

Fig. 2 (b) shows the flow chart according to the initial carrier allocation method of the embodiment of the invention;

Fig. 2 (c) shows the flow chart according to the carrier reallocation method of the embodiment of the invention;

Fig. 3 is the curve chart that the simulation result with the present invention and prior art compares;

Fig. 4 shows the schematic diagram that is used to explain TDMA OFDM; And

Fig. 5 shows the multi-user multi-antenna ofdm system.

Embodiment

Below in conjunction with accompanying drawing the present invention is specified.Be noted that described embodiment only is for illustrative purposes, rather than limitation of the scope of the invention.

Embodiment 1: the single antenna ofdm system

The applied multi-user's single antenna of the present invention ofdm system as shown in Figure 1.

At transmitting terminal, adopt 101 pairs of incoming bit streams of encoder to carry out chnnel coding with antinoise; Adopt 102 pairs of coding outputs of interleaver to carry out interleaving treatment to reduce the bit stream correlation; Adopt modulator 103 that the bit stream of interleaver output is modulated to symbols streams; Insertion pilot module 104 is finished and insert the pilot frequency sequence that is used for timing, channel estimating in being sent symbols streams; Adopt 105 pairs of stream of modulation symbols of IDFT processor to make N _cThe contrary discrete fourier transform (IDFT) of point; Symbols streams after 106 couples of IDFT of CP module handle adds Cyclic Prefix (CP); Adopt radio frequency (RF) chain 107 that baseband signalling is transmitted into channel by antenna 108 after carrier modulation.

At receiving terminal, RX module 110 down-converts to baseband signalling to the carrier signal that receives from antenna end 109～109 '; Removing CP module 111～111 ' deletes the Cyclic Prefix of OFDM symbol; DFT module 112～112 ' is carried out N _cDian Lisanfushi conversion (DFT); Channel estimation module 116～116 ' utilizes the pilot frequency sequence that sends to estimate channel gain, and utilizes feedback channel that estimated result is fed back to transmitting terminal carrier allocation module 117; Signal after the DFT conversion is the recovering information bit stream after demodulation 113～113 ', deinterleaving 114～114 ', decoding 115～115 '.

Transmitting terminal carrier allocation module 117 is according to each user's information dynamic assignment carrier waves such as received signal to noise ratio, and allocation result is delivered to transmitting terminal IDFT module 105 and receiving terminal DFT module 112, forms the OFDM symbol according to allocation of carriers information in these modules.

Carrier wave (frequency) resource allocation of ofdm system is discussed below.Among the present invention, total K the user of supposing the system and N carrier wave, each allocation of carriers equal-wattage and can only be by user's utilization.Therefore, can make to give a definition:

(A) the interchannel noise ratio of n the carrier wave of user k is $H_{k,n}=\frac{h_{k,n}^2}{N_{0}B/N},$ H wherein _{K, n}Be the channel gain of n the carrier wave of user k, N ₀Be the white Gauss noise power spectral density, B is a channel width, noise power σ ²=N ₀B/N.If distributing to the power of n the carrier wave of user k is p _{K, n}, then this user's received signal noise ratio is SNR _{K, n}=p _{K, n}H _{K, n}, p _{K, n}Satisfy total power constraint $\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{p}_{k,n}\≤P_{\mathrm{tot}}.$

(B) speed of n the carrier wave of user k is r _{K, n}=log ₂(1+SNR _{K, n}), the capacity of user k (spectrum efficiency) is $C_k=\stackrel{N_k}{\underset{n=1}{\mathrm{\Σ}}}\frac{1}{N_k}{\mathrm{\ρ}}_{k,n}{r}_{k,n},$ Speed is $R_k=\underset{n=1}{\overset{N_k}{\mathrm{\Σ}}}\frac{B}{N_k}{\mathrm{\ρ}}_{k,n}{r}_{k,n},$ N wherein _kFor distributing to the carrier number of user k, ρ _{K, n}∈ [0,1] represents that its value is 1 or 0 only, depends on whether carrier wave n is assigned to user k, if carrier wave n is assigned to user k, then ρ _{K, n}=1, otherwise ρ _{K, n}=0; All users' traversal total capacity is $C=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{C}_k.$

(C) for guaranteeing the fairness between the user, according to user's mean data rate, the ratio that limits each user rate is R ₁: R ₂: ...: R _K=φ ₁: φ ₂: ...: φ _K

(D) the ratio speed of definition user k is R _k/ φ _k

The thought of allocation of carriers algorithm proposed by the invention is to give the allocation of carriers of peaked channal noise ratio the user obtaining heap(ed) capacity as far as possible, and according to the principle of allocation of carriers being given minimum ratio rate users to guarantee fairness between the user.Arthmetic statement is: at first, carry out initialization according to all carrier waves of comparison of the speed between each user and distribute S2a01; Then, according to the principle of the allocation of carriers of peaked channal noise ratio being given minimum ratio rate users, to the carrier wave of just distributing to the user S2a02 that reallocates, shown in Fig. 2 (a)～(c).Its step is as follows:

The first step: initial carrier allocation.

(1) determines to distribute to each user's carrier number N according to the ratio of the speed between each user _kEven, N ₁: N ₂: ...: N _K=φ ₁: φ ₂: ...: φ _K, to guarantee the fairness between the user.Thus, can obtain distributing to the carrier number of user k

Round under the expression).S2b01

(2) because of having adopted the approximate processing that rounds in (1) step, so there is the carrier wave N that is not assigned with ^*, it deducts the carrier wave of distributing to each user for total carrier number, promptly $N^{*}=N-\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{N}_k.$ By handling these allocation of carriers for the user of higher channel noise ratio, distribute a carrier wave to give the user of high channel noise ratio earlier, the carrier wave of reallocate is given the user of inferior high channel noise ratio, by that analogy.S2b02

(3) original carrier counting n=1; S2b03

(4) calculate each subscriber channel noise ratio of this carrier wave correspondence, by relatively obtaining and the user of high channel noise ratio; S2b04

(5) this allocation of carriers is given the user of high channel noise ratio; S2b05

(6) more be newly assigned to this user's carrier number N _k=N _k+ 1; S2b06

(7) upgrade carrier wave counting n=n+1; S2b07

(8) judge, if n is not more than N ^*, change (S2b04) step iteration; Otherwise, carry out following each step.S2b08

Second step: carrier reallocation.

According to the principle of the allocation of carriers of peaked channal noise ratio being given minimum ratio rate users, at the beginning of distribute to the user carrier wave reallocate several steps below its divides.

(1) initialization S2c01

To user k ∈ [1, K] arbitrarily, and carrier wave n ∈ [1, N-N ^*], it is ρ that definition is not given user k distributing carrier wave n _{K, n}=0;

To user k ∈ [1, K] arbitrarily, the speed R of user k _{K, n}=0;

Carrier set N=[1 2 ... N-N ^*].

(2) distribute the carrier wave of its peaked channal noise ratio for each user.When in (3) step the user being carried out fair allocation of carriers, need known every user rate R _kSo, in this step, distribute the carrier wave of high channel noise ratio for earlier every user, calculate each user rate initial value thus.

1) user number counting k=1; S2c02

2) calculate each carrier channel noise ratio of user k correspondence, by relatively obtaining the carrier wave of high channel noise ratio; S2c03

3) give user k, i.e. ρ this allocation of carriers _{K, n}=1; S2c04

4) upgrade carrier set, promptly concentrate to deduct the carrier number that has distributed from total carrier wave

N _k＝N _k-1，N＝N-{n}； S2c05

5) the speed R in the redetermination (B) more _kS2c06

6) upgrade user number counting k=k+1; S2c07

7) judge,, change S2c03 step iteration if k is not more than K; Otherwise, carry out following each step.S2c08

By 1)～7) step, each simultaneously, calculates speed R with being assigned with per family-carrier wave of individual high channel noise ratio _kInitial value.

(3) give user's distributing carrier wave of minimum ratio speed.

8) find minimum scale speed R _k/ φ _kUser k; S2c09

9) find the peaked channal noise of user k to compare carrier wave n; S2c10

10) in this time slot, distribute n carrier wave to give user k, i.e. ρ _{K, n}=1;

S2c11

11) upgrade carrier set N _k=N _k-1, N=N-{n}; S2c12

12) the speed R in the redetermination (B) more _kS2c13

13) judge,, change S2c09 step iteration if N=is not null set, otherwise, finish.S2c14

By 8)～13) step, find the user of minimum scale speed earlier, and in this time slot, this user's peaked channal noise than this user of allocation of carriers, like this, is carried out allocation of carriers according to user's ratio speed successively, promptly give user's distributing carrier wave of minimum scale speed earlier, give user's distributing carrier wave of time minimum scale speed then, by that analogy, guaranteed the subscribers carrier distributional equity.

Verify the performance of the allocation of carriers algorithm that proposes by l-G simulation test, simulation parameter is as follows: system has 64 carrier waves, total bandwidth is 1MHz, gross power is normalized to 1, noise power spectral density is-80dBW/Hz, 6 footpath channels, every footpath power time delay distributes and is exponential damping, and the ratio of user rate ratio is φ ₁: φ ₂: ...: φ _K=2: 1: ...: 1.When utilizing these parameter distributing carrier wave, if the user is 4, the carrier number that is calculated each user's distribution by the S2b01 step is 25,12,12,12, the carrier wave N that then is not assigned with ^*=64-(25+12+12+12)=3.To these 3 carrier waves, utilize each step of S2b01～S2b07 to distribute to the user; Then, each user is obtained carrier wave, utilize each step of S2c01～S2c14 to carry out carrier reallocation.Simulation result such as Fig. 4 can see, the power system capacity of the dynamic carrier distribution method of proposition and be higher than general static resource allocation method TDMA (as Fig. 4), and it distributes different time-gap for each user, and monopolizes all carrier waves in a time slot.

Embodiment 2: many antennas ofdm system

Consider the down link (broadcast channel) of the MIMO ofdm system of employing space division multiplexing mode of operation, transmitting terminal (base station BS) is installed N _TWidth of cloth antenna is installed N at each user's receiving terminal _RWidth of cloth antenna.

MIMO ofdm system such as Fig. 5 of proposing, its operation principle is: at transmitting terminal, input bit is flowed through and is multiplexed into every transmit antennas end 109～109 ' after the serial/parallel conversion 101; To the bit stream of every antenna branch end, adopt encoder 102～102 ' that incoming bit stream is carried out chnnel coding with antinoise; Adopt interleaver 103～103 ' that coding is exported and carry out interleaving treatment to reduce the bit stream correlation; Adopt modulator 104～104 ' that the interleaver output bit flow is modulated to symbols streams; Insertion pilot module 105～105 ' is finished and insert the pilot frequency sequence that is used for timing, channel estimating in being sent symbols streams; Adopt IDFT processor 106～106 ' that stream of modulation symbols is made N _cThe contrary discrete fourier transform of point; Symbols streams after the CP module is handled 107～107 ' IDFT adds Cyclic Prefix; Pre-filtering (emission filtering) device after the antenna transmission Signal Pretreatment, utilizes rf chain 109～109 ' that baseband signalling is transmitted into channel after carrier modulation more than 108 pairs.

At receiving terminal, RX module 112～112 ', 121～121 ' down-converts to baseband signalling to the carrier signal that receives from antenna end 111～111 ', 120～120 '; Synchronization module 113,122 is finished frame synchronization, tracking; The function of receiving filter 114,123 is corresponding with prefilter, the compensation received signal; Removing CP module 115～115 ', 124～124 ' deletes the Cyclic Prefix of OFDM symbol; DFT module 116～116 ', 125～125 ' is carried out N _cThe Dian Lisanfushi conversion; Channel estimation module 118,127 utilizes the pilot frequency sequence that sends to estimate channel gain, and utilizes feedback channel that estimated result is fed back to the transmitting terminal carrier wave and select module 119; Signal after the DFT conversion is the recovering information bit stream after demodulation, deinterleaving, decoding 117,126.

Transmitting terminal carrier allocation module 119 is according to every user's information dynamic assignment carrier waves such as received signal to noise ratio, and allocation result delivered to transmitting terminal IDFT module 106～106 ' and receiving terminal DFT module 116～116 ', in these modules, form the OFDM symbol according to allocation of carriers information.

The main advantage of the mimo system of space division multiplexing mode of operation is to obtain high channel capacity (spectrum efficiency).For the space division multiplexing multiaerial system, being x if transmit, is x=Vx after the pre-filtering, and the signal after the channel H transmission is y=H x+ w=HVx+ w, back signal vector y and y=U accept filter ^HY=U ^H(HVx+ w), wherein U is for launching pre-filtering battle array and V for accepting filter battle array, and " T " represents transposition, the Hermite transposition of " H " representing matrix, channel matrix is

Element h wherein _IjBe the channel fading coefficient of transmitting antenna i to reception antenna j.After receiving terminal utilizes feedback channel that channel condition information is returned to transmitting terminal, channel matrix is carried out characteristic value (SVD) branch solve H=U Λ V ^H, unitary matrix U, V satisfy UU ^H=I, VV ^H=I; Diagonal matrix Λ=diag (λ ₁λ ₂λ _k), λ ₁＞λ ₂＞...＞λ _kBe the characteristic value of H, so the output y=U that accepts filter ^H(U Λ V ^H) (Vx)+U ^HW=Λ x+w, w is a noise in the formula.As seen,, can resolve into the single output of a plurality of single inputs of parallel independent (SISO) channel to mimo channel, decompose the number that the parallel sub-channels number that obtains equals nonzero eigenvalue among the H by characteristic value decomposition.

Like this, can be applied to the carrier allocation method of aforementioned single antenna ofdm system in many antennas ofdm system, embodiment 1 is seen in the description of this algorithm flow, repeat no more here, below with an example explanation.

Adopt parameter same as described above, setting up departments altogether has 64 carrier waves, and emission, receiving terminal are installed 2 width of cloth antennas, and 4 users are arranged, and the ratio of user rate ratio is φ ₁: φ ₂: φ ₃: φ ₄=2: 1: 1: 1.Decompose through SVD, mimo channel is converted into the SISO channel.Like this, promptly the assignable OFDM carrier wave of system is 64 * 2=128.During to these parameter distributing carrier wave, the carrier number that is calculated each user's distribution by the S2b01 step is 51,25,25,25, the carrier wave N that then is not assigned with ^*=128-(51+25+25+25)=2.To these 2 carrier waves, utilize each step of S2b01～S2b07 to carry out original allocation; Then, to distributing to every user's carrier wave, utilize S2c01～S2c14 to carry out carrier reallocation.

Although illustrated and described the present invention at exemplary embodiments, will be understood by those skilled in the art that, under the situation that does not break away from the spirit and scope of the present invention, can carry out various other change, replacement and interpolations.Therefore, the present invention should not be understood that to be limited to above-mentioned particular instance, and should be limited by claims.

Claims (8)

1, a kind of method of the user being carried out the dynamic carrier distribution of fairness in multi-user orthogonal frequency division multiplexing system comprises:

The initial carrier allocation step is determined to distribute to each user's carrier number according to the ratio of the speed between each user; For the carrier wave that is not assigned with, it is distributed to the user with higher channel noise ratio;

The carrier reallocation step according to the principle of the allocation of carriers of peaked channal noise ratio being given minimum ratio rate users, reallocates for user's carrier wave to determining original allocation.

2, method according to claim 1 is characterized in that described carrier reallocation step may further comprise the steps:

Initialization step;

The carrier wave of distributing its peaked channal noise ratio for each user is with the initial value of the speed of determining each user; And

According to the ratio and the above-mentioned speed initial value of each user's speed, give user's distributing carrier wave of minimum ratio speed, to guarantee the subscribers carrier distributional equity.

3, method according to claim 1 is characterized in that described initial carrier allocation step may further comprise the steps:

Determine to distribute to each user's carrier number according to the ratio of the speed between each user;

Deduct the carrier wave that the carrier wave of distributing to each user is not assigned with total carrier number;

For each carrier wave that is not assigned with, calculate the subscriber channel noise ratio of this carrier wave correspondence, by relatively, obtain the user of high channel noise ratio;

This allocation of carriers is given the user of described high channel noise ratio;

More be newly assigned to this user's carrier number; And

Continuation distributes the carrier wave that is not assigned with, till it is all distributed to the user.

4, according to claim 1 or 3 described methods, it is characterized in that comprising the step that defines following parameter:

Total K the user of system and N carrier wave, the power that each allocation of carriers is identical, and can only be utilized by a user;

(A) the interchannel noise ratio of n the carrier wave of user k is $H_{k,n}=\frac{h_{k,n}^2}{N_{0}B/N},$ H wherein _{K, n}Be the channel gain of n the carrier wave of user k, N ₀Be the white Gauss noise power spectral density, B is a channel width, noise power σ ²=N ₀B/N is p if distribute to the power of n the carrier wave of user k _{K, n}, then this user's received signal noise ratio is SNR _{K, n}=p _{K, n}H _{K, n}, p _{K, n}Satisfy total power constraint $\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}{p}_{k,n}\≤P_{\mathrm{tot}},$ P _TotBe gross power;

(B) speed of n the carrier wave of user k is r _{K, n}=1og ₂(1+SNR _{K, n}), the capacity of user k (spectrum efficiency) is $C_k=\underset{n=1}{\overset{N_k}{\mathrm{\Σ}}}\frac{1}{N_k}{\mathrm{\ρ}}_{k,n}{r}_{k,n},$ Speed is $R_k=\underset{n=1}{\overset{N_k}{\mathrm{\Σ}}}\frac{B}{N_k}{\mathrm{\ρ}}_{k,n}{r}_{k,n},$ N wherein _kFor distributing to the carrier number of user k, ρ _{K, n}∈ [0,1] represents that its value is 1 or 0 only, depends on whether carrier wave n is assigned to user k, if carrier wave n is assigned to user k, then ρ _{K, n}=1, otherwise ρ _{K, n}=0; All users' traversal total capacity is $C=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{C}_k;$

(C) for guaranteeing the fairness between the user, according to user's mean data rate, the ratio that limits each user rate is R ₁: R ₂: ...: R _K=φ ₁: φ ₂: ...: φ _KAnd

(D) the ratio speed of definition user k is R _k/ φ _k,

Wherein said initial carrier allocation step is:

According to the ratio of the speed between each user, determine to distribute to each user's carrier number N _kEven, N ₁: N ₂: ...: N _K=φ ₁: φ ₂: ...: φ _K, obtain distributing to the carrier number of user k thus

Round under the expression;

To unappropriated carrier wave $N^{*}=N-\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{N}_k,$ These allocation of carriers are given the user with higher channel noise ratio: distribute a carrier wave to give the user of high channel noise ratio earlier, the carrier wave of reallocate is given the user of inferior high channel noise ratio, and the rest may be inferred, till whole distribution.

5, method according to claim 4 is characterized in that described carrier reallocation step is:

The carrier wave of distributing its peaked channal noise ratio for each user is to determine each user's speed R _kInitial value:

Calculate each carrier channel noise ratio of user k correspondence, by relatively obtaining the carrier wave of high channel noise ratio;

Give user k, i.e. ρ this allocation of carriers _{K, n}=1;

Upgrade carrier set, concentrate from total carrier wave to deduct the carrier number N that has distributed _k=N _k-1, N=N-{n};

Renewal rate R _k

Judge at next user;

According to user's ratio speed in proper order, give user's distributing carrier wave successively from low to high, to guarantee the fairness between the user:

Find the user k of minimum scale speed and the peaked channal noise of user k to compare carrier wave n;

In this time slot, distribute n carrier wave to give user k;

Upgrade carrier set N _k=N _k-1, N=N-{n} and speed R _k

Judge that if N=changes the above-mentioned user's of minimum scale speed the step that finds and carries out iteration not for null set, otherwise described carrier reallocation finishes.

6,, it is characterized in that described multi-user orthogonal frequency division multiplexing system is multi-user's single antenna ofdm system according to any one the described method in the claim 1 to 5.

7,, it is characterized in that described multi-user orthogonal frequency division multiplexing system is a multi-user and multi-antenna OFDM system according to any one the described method in the claim 1 to 5.

8, a kind of method of the user being carried out the dynamic carrier distribution of fairness in multi-user and multi-antenna OFDM system comprises step:

Transmitting terminal emission pilot frequency sequence, receiving terminal is estimated the channel gain matrix coefficient, and utilizes feedback channel that this information is returned to transmitting terminal;

Transmitting terminal carries out characteristic value decomposition to channel matrix, thereby multi-antenna channel is decomposed into the single delivery channel of a plurality of single inputs of parallel independent; And

At the single delivery channel of described a plurality of single inputs, use according to any one the described dynamic carrier distribution method in the claim 1 to 5.

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