CN1862984A - Power distributing method of ensuring signal quality in multi-channel multi-antenna communication system - Google Patents

Abstract

The invention discloses the power assigning method for assuring the signal quality in the communicating system with several antennas and several channels in the communicating domain, the filling water power assignment on the base of the character module; if the character module of the assigned power is less than the need least power by the satisfaction of the least SNR is existing, the least need power can be assigned to the character modules, then the odd general power uses the filling water power assignment in the other character modules; if the assigned power satisfies the character module least power needing, the assignment finishes, otherwise, the power assignment is conducted using the filling water rule. The invention conquers the defect of the existing technology cannot satisfying the signal quality, so the signal transferring quality can be assured in the system with the several channels, the frequency table efficiency can be used fully.

Description

The power distribution method that ensures signal quality in the multi-channel multi-antenna communication system

Technical field

The present invention relates to wireless communication field, relate in particular to multi-channel multi-antenna (be multiple-input and multiple-output, MIMO, Multiple-Input, Multiple-Output) power resource allocation in the wireless communication system, guarantee the method for signal transmission quality.

Background technology

The MIMO technology is the important breakthrough of wireless communication field intelligent antenna technology.This technology can improve the capability of communication system and the availability of frequency spectrum exponentially under the situation that does not increase bandwidth.Generally believe that MIMO will be the key technology that the new generation of wireless communication system must adopt.Mimo system all adopts a plurality of antennas at transmitting terminal and receiving terminal, a plurality of parallel spatial channels between these a plurality of transmitting antennas and a plurality of reception antenna, have been formed, by these parallel spatial channel transmission datas, make the data signal quality or the transmission rate that receive be improved, thereby realize the higher capacity of communication system and the availability of frequency spectrum.

The independent parallel transmission of a plurality of spatial sub-channels can be realized in the mimo system, different independent data streams can be on different spatial sub-channels, transmitted.And this independent data stream is because the needs of communication may need different minimum transmission qualities to guarantee when supporting specific data rate, as the error rate (BER).Provide minimum signal to noise ratio (snr) to guarantee it is effective ways realizing signal transmission quality, and this utilize power division to realize usually.And present prior art can't realize such requirement.The power division problem in the multiaerial system that at present many documents arranged, the I.Emre Telatar of Lucent Bell Laboratory is at " Capacity of multi-antenna Gaussian channels " Europe Transactions on Telecommunications, Vol.10, No.6, pp.585-595, studied the capacity problem of many antennas Gaussian channel in the document of Nov.-Dec.1999, the result shows, when channel condition information (CSI) is known completely by system, the optimal power allocation of many antennas Gaussian channel power system capacity is the power division (water-filling power allocation) of pouring water, this technology has provided under complete CSI condition, realize the power distribution method of preferred channels capacity, but do not have to consider to have the power division of channel quality requirement.QualCom company distributes total transmitting power to realize the more technology of spectral efficient in multichannel communication system thereby provided in patent application (application number is US 2003/0139196) " reallocation of surplus power in the complete channel state information multi-input multi-output system (Reallocation of excess power for full channel-state information (CSI) multiple-input multiple-output (MIMO) systems) ".Total transmitting power begins based on a specific power allocation scheme (as the power of pouring water), such distribution may cause to some channel more power that realize SNR (as realizing the required SNR of maximum data rate) demand, thereby makes transmission channel be in the zone of saturation.Be necessary to redistribute the unnecessary transmitting power that is in the zone of saturation like this and be lower than the channel of zone of saturation to other.Thereby can obtain higher data rate at relatively poor transmission channel and do not sacrifice the performance of better transmission channel.In addition, give the power distribution method of considering discrete data rates, minimize the method for transmitting power during with the realization maximum data rate, this technology has considered to have under the condition of maximum S R requirement, improves spectrum utilization efficiency thereby surplus power is distributed to other channels.But do not have to consider to have the power division that minimum SNR requires.In another part patent application (application number is US 2003/0072379) " method and apparatus (Method and apparatus for determining powerallocation in a MIMO communication system) of decision power division in the multiple-input-multiple-output communication system " of QualCom company, consider that each antenna has the MIMO communication system of limited power, designed one and determined the method and apparatus that energy level distributes for each OFDM carrier frequency of each transmitting antenna.In the MIMO communication system, if system can realize that beam shaping and all transmitting antennas have a total transmission power limit, then can pass through the irrigation method maximized system capacity by transmitting antenna.If but each antenna all has transmission power limit, perhaps can not use beam shaping, then be necessary to find the optimum allocation of subcarrier transmitting power on each transmitting antenna, give feature mode because can't directly control transmit power allocations in this case.Because the MIMO spatial sub-channel intercouples on each frequency subchannels when the feature mode decomposition can not provide the orthogonal frequency subchannel, can't use irrigation method.The target of assigning process is to calculate the energy of each subcarrier on each antenna and the parameter of pouring water.The use alternative manner is found the solution, and uses the Newton-Raphson method and finds the solution nonlinear equation.This technology has considered that each antenna has the method for power division under the condition of maximum power constraint, does not consider that channel has the power allocation scheme of signal quality demand.

As a whole, existing power distributing technique does not all have the minimum channel quality requirement, guarantees thereby can't satisfy service quality.

Summary of the invention

Technical problem to be solved by this invention is to overcome the shortcoming that can't ensure signal quality that prior art exists, a kind ofly can in multichannel system, guarantee signal transmission quality in the hope of proposing, and make full use of the power distribution method that ensures signal quality in the multi-channel multi-antenna communication system of spectrum efficiency.

The power distribution method that ensures signal quality in the multi-channel multi-antenna communication system of the present invention may further comprise the steps:

The power division of on all feature modes, pouring water;

If exist the power that distributes less than the feature mode that satisfies the required minimum power of minimum SNR, just minimum power demand is distributed to this feature mode, in remaining feature mode set, use the power division of pouring water with remaining gross power then;

If distribute power to satisfy each feature mode minimal power requirements, then distribute to finish, otherwise continue to utilize the rule of pouring water to carry out power division.

The method of the invention further may further comprise the steps:

Step 1: initialization maximum transmission power P _T, channel response matrix H carries out feature mode and decomposes, and determines eigenvalue and treats the feature mode set F of power division, set G=Φ (Φ is an empty set), set G=F-G, iterations k=0; H is carried out feature mode decompose, then forming set F greater than zero feature mode;

Step 2: define the feature mode subclass E that minimum SNR requires, calculate the required minimum power P of each feature mode among the E _i ^MinIn feature mode set F, select to form feature mode subclass E, each feature mode power demand P among the subset of computations E greater than zero element by the minimum SNR value that minimum SNR requires or requires _i ^Min

Step 3: if $\underset{i\∈E}{\mathrm{\Σ}}{P}_i^{\min }\≤P_T,$ Change step 5: otherwise change step 4:

Step 4: if $\underset{i\∈E}{\mathrm{\Σ}}{P}_i^{\min }>P_T,$ Be that gross power can't satisfy whole minimum power demand sums, then system is in overload, solve by load control this moment, according to feature mode ordering from big to small among the subclass E, remove subchannel one by one with minimal characteristic mode value, enough distribute other spatial sub-channels of requiring for minimum SNR up to gross power, so one or more subchannels that the feature mode value is minimum be the spatial sub-channel condition the poorest will not distribute power; Upgrade the feature mode set F of power to be allocated, have $\underset{i\∈F}{\mathrm{\Σ}}{P}_i^{\min }\≤P_T,$ Change step 5;

Step 5:k=k+1, set GIn, at gross power P _TThe following use power distribution method of pouring water is that each feature mode distributes power P _i(k);

Step 6: if having for each feature mode among the set E $P_i\left(k\right)\≥P_i^{\min },$ Then change step 9; Otherwise, change step 7;

Step 7: set GIn satisfy $P_i\left(k\right)\≤P_i^{\min }$ Feature mode add set G, distribute power to make that wherein the power of each feature mode is minimum power for set G, promptly $P_j\left(k\right)=P_j^{\min }(j\∈G);$ Then total surplus power is $P_T=P_T-\underset{j\∈G}{\mathrm{\Σ}}{P}_j^{\min },$ Upgrade set G

Step 8: if G=Φ then changes step 9; Otherwise change step 5.

Step 9: the power division process finishes.

The method of the invention also may further include following steps:

Step 1: initialization maximum transmission power P _T, channel response matrix H carries out feature mode and decomposes, and determines eigenvalue and treats the feature mode set F of power division, initial sets G=B=Φ (Φ is an empty set), set Z=F-(G ∪ B), iterations k=0; H is carried out feature mode decompose, then forming set F greater than zero feature mode;

Step 2: define the feature mode subclass E that minimum SNR requires, calculate the required minimum power P of each feature mode among the E _i ^MinDefine the feature mode subset D that maximum S R requires, calculate the required maximum power P of each feature mode among the D _j ^MaxIf among the set F all feature modes all have maximum S R to require and $\underset{i\&Element;F}{\mathrm{\&Sigma;}}{P}_i^{\max }<P_T,$ Then make maximum transmission power be $P_T=\underset{i\&Element;F}{\mathrm{\&Sigma;}}{P}_i^{\max };$

Step 3: if $\underset{i\&Element;E}{\mathrm{\&Sigma;}}{P}_i^{\min }\&le;P_T,$ Change step 5; Otherwise, change step 4;

Step 4: if $\underset{i\&Element;E}{\mathrm{\&Sigma;}}{P}_i^{\min }>P_T,$ Be that gross power can't satisfy whole minimum power demand sums, then system is in overload, solve by load control this moment, according to feature mode ordering from big to small among the subclass E, remove subchannel one by one with minimal characteristic mode value, enough distribute other spatial sub-channels of requiring for minimum SNR up to gross power, so one or more subchannels that the feature mode value is minimum be the spatial sub-channel condition the poorest will not distribute power.Upgrade the feature mode set F of power to be allocated, have $\underset{i\&Element;F}{\mathrm{\&Sigma;}}{P}_i^{\min }\&le;P_T,$ Change step 5;

Step 5:k=k+1 is among the set Z, at gross power P _TThe following use power distribution method of pouring water is that each feature mode distributes power P _i(k);

Step 6: if having for each feature mode among the set E $P_i\left(k\right)\&GreaterEqual;P_i^{\min },$ And each feature mode among the set D has $P_j\left(k\right)\&le;P_j^{\max },$ Then change step 9; Otherwise change step 7;

Step 7: satisfying among the set Z $P_i\left(k\right)<P_i^{\min }$ Feature mode add set G, distribute power to make that wherein the power of each feature mode is minimum power for set G, promptly $P_i\left(k\right)=P_i^{\min }(i\&Element;G);$ Satisfying among the set Z $P_j\left(k\right)>P_i^{\max }$ Feature mode add set B, distribute power to make that to set B wherein the power of each feature mode is maximum power, promptly $P_j\left(k\right)=P_j^{\max }(j\&Element;B);$ Then total surplus power is $P_T=P_T-\underset{i\&Element;G}{\mathrm{\&Sigma;}}{P}_i^{\min }-\underset{j\&Element;B}{\mathrm{\&Sigma;}}{P}_j^{\max },$ Upgrade set Z;

Step 8:, then change step 9 if Z=is Φ: otherwise change step 5;

Step 9: the power division process finishes.

The present invention has provided the technology of distributing total transmitting power to realize spectral efficient simultaneously in the MIMO communication system, realized the optimal power allocation method under the minimum SNR demand condition of assurance channel.Characteristics of the present invention are transmission qualities that power division has guaranteed channel, and have obtained optimum channel capacity, have efficiently utilized wireless frequency spectrum.

Description of drawings

Fig. 1 is the method for the invention workflow diagram;

Fig. 2 is a mimo system structural representation in the method for the invention.

Embodiment

Power division is the important method that Radio Resource is optimized in multi-channel multi-antenna (MIMO) wireless communication system, also is the important means that improves the system channel capacity.The present invention has provided the technology of distributing total transmitting power to realize spectral efficient simultaneously in the MIMO communication system, realized the optimal power allocation method under the minimum SNR demand condition of assurance channel.Characteristics of the present invention are transmission qualities that power division has guaranteed channel, and have obtained optimum channel capacity.

The present invention includes several basic steps as shown in Figure 1.

Step 1 initialization maximum transmission power P _T, channel response matrix H carries out feature mode and decomposes, and determines eigenvalue and treats the feature mode set F of power division, set G=Φ (Φ is an empty set), set G=F-G, iterations k=0.

H is carried out feature mode decompose, then forming set F greater than zero feature mode.

Step 2 defines the feature mode subclass E that minimum SNR requires, and calculates the required minimum power P of each feature mode among the E _i ^Min

In feature mode set F, select to form feature mode subclass E, each feature mode power demand P among the subset of computations E greater than zero element by the minimum SNR value that minimum SNR requires or requires _i ^Min

If step 3 $\underset{i\&Element;E}{\mathrm{\&Sigma;}}{P}_i^{\min }\&le;P_T,$ Change step 5; Otherwise, change step 4.

If step 4 $\underset{i\&Element;E}{\mathrm{\&Sigma;}}{P}_i^{\min }>P_T,$ Be that gross power can't satisfy whole minimum power demand sums, then system is in overload, solve by load control this moment, according to feature mode ordering from big to small among the subclass E, remove subchannel one by one with minimal characteristic mode value, enough distribute other spatial sub-channels of requiring for minimum SNR up to gross power, so one or more subchannels that the feature mode value is minimum be the spatial sub-channel condition the poorest will not distribute power.Upgrade the feature mode set F of power to be allocated, have $\underset{i\&Element;F}{\mathrm{\&Sigma;}}{P}_i^{\min }\&le;P_T,$ Change step 5.

Step 5k=k+1, set GIn, at gross power P _TThe following use power distribution method of pouring water is that each feature mode distributes power P _i(k).

If step 6 has for each feature mode among the set E $P_i\left(k\right)\&GreaterEqual;P_i^{\min },$ Then change step 9.

Otherwise, change step 7.

Step 7 is set GIn satisfy $P_i\left(k\right)\&le;P_i^{\min }$ Feature mode add set G, distribute power to make that wherein the power of each feature mode is minimum power for set G, promptly $P_j\left(k\right)=P_j^{\min }(j\&Element;G);$ Then total surplus power is $P_T=P_T-\underset{j\&Element;G}{\mathrm{\&Sigma;}}{P}_j^{\min },$ Upgrade set G

If step 8 G=Φ then changes step 9;

Otherwise, change step 5.

Step 9 power division process finishes.

Other possible power distribution methods have:

Additive method one: at first require required power, the power division of then dump power being poured water on all spatial sub-channels for the spatial sub-channel basic of distribution SNR that has minimum SNR to require.The power that spatial sub-channel distributed that has minimum SNR to require like this is two sub-distribution power sums.

Additive method two: at first for the channel allocation that has minimum SNR to require requires required power according to SNR, the power division of then dump power being poured water on all the other spatial sub-channels that do not have minimum SNR to require.

In addition, the present invention gives a power distribution method that guarantees minimum and high quality-of-service requirement simultaneously.

As previously mentioned, the optimal power allocation method that proposes of the present invention is that can guaranteeing of proposing on the basis that utilizes the existing power distribution method of pouring water transmitted the power distribution method that the minimum quality of service of data requires.And in the practical application, because the performance limitations of portable terminal or specific application demand, also need to satisfy the upper limit of the quality of service requirement of transmission data, so not only can guarantee user's demand, and utilization ratio that can Radio Resource.This can be by in the method that the method for the prior art 2 of Qualcomm is attached to the present invention's proposition, and promptly in actual wireless was used, such combination can improve the performance and the spectrum utilization efficiency of system when satisfying the active service quality requirement.Provide the implementation algorithm step that guarantees the power distribution method that minimum and high quality-of-service requires in conjunction with the method for the prior art 2 of Qualcomm simultaneously below:

Step 1 initialization maximum transmission power P _T, channel response matrix H carries out feature mode and decomposes, and determines eigenvalue and treats the feature mode set F of power division, initial sets G=B=Φ (Φ is an empty set), set Z=F-(G ∪ B), iterations k=0.

H is carried out feature mode decompose, then forming set F greater than zero feature mode.

Step 2 defines the feature mode subclass E that minimum SNR requires, and calculates the required minimum power P of each feature mode among the E _i ^MinDefine the feature mode subset D that maximum S R requires, calculate the required maximum power P of each feature mode among the D _i ^MaxIf among the set F all feature modes all have maximum S R to require and $\underset{i\&Element;F}{\mathrm{\&Sigma;}}{P}_i^{\max }<P_T,$ Then make maximum transmission power be $P_T=\underset{i\&Element;F}{\mathrm{\&Sigma;}}{P}_i^{\max }.$

If step 3 $\underset{i\&Element;E}{\mathrm{\&Sigma;}}{P}_i^{\min }\&le;P_T,$ Change step 5; Otherwise, change step 4.

If step 4 $\underset{i\&Element;E}{\mathrm{\&Sigma;}}{P}_i^{\min }>P_T,$ Be that gross power can't satisfy whole minimum power demand sums, then system is in overload, solve by load control this moment, according to feature mode ordering from big to small among the subclass E, remove subchannel one by one with minimal characteristic mode value, enough distribute other spatial sub-channels of requiring for minimum SNR up to gross power, so one or more subchannels that the feature mode value is minimum be the spatial sub-channel condition the poorest will not distribute power.Upgrade the feature mode set F of power to be allocated, have $\underset{i\&Element;F}{\mathrm{\&Sigma;}}{P}_i^{\min }\&le;P_T,$ Change step 5.

Step 5k=k+1 is among the set Z, at gross power P _TThe following use power distribution method of pouring water is that each feature mode distributes power P _i(k).

If step 6 has for each feature mode among the set E $P_i\left(k\right)\&GreaterEqual;P_i^{\min },$ And each feature mode among the set D has $P_j\left(k\right)\&le;P_j^{\max },$ Then change step 9.

Otherwise, change step 7.

Step 7 is satisfying among the set Z $P_i\left(k\right)<P_i^{\min }$ Feature mode add set G, distribute power to make that wherein the power of each feature mode is minimum power for set G, promptly $P_i\left(k\right)=P_i^{\min }(i\&Element;G)$ Satisfying among the set Z $P_j\left(k\right)>P_i^{\max }$ Feature mode add set B, distribute power to make that to set B wherein the power of each feature mode is maximum power, promptly $P_j\left(k\right)=P_j^{\max }(j\&Element;B)$ Then total surplus power is $P_T=P_T-\underset{i\&Element;G}{\mathrm{\&Sigma;}}{P}_i^{\min }-\underset{j\&Element;B}{\mathrm{\&Sigma;}}{P}_j^{\max },$ Upgrade set Z.

If step 8 Z=is Φ, then change step 9;

Otherwise, change step 5.

Step 9 power division process finishes.

Introduce a specific embodiment below power distribution method of the present invention is described.Concrete mimo system structure such as Fig. 2 among the embodiment.The MIMO communication system has N transmitting antenna and M reception antenna, channel between this N transmitting antenna and M the reception antenna can be broken down into L independently subchannel, (N, M), the number of subchannel is by the feature mode number decision of mimo channel for L＜=min.And feature mode depends on channel response matrix H, promptly describes the channel response between N transmitting antenna and M the reception antenna, can be expressed as:

$H=\left(\begin{array}{ccc}{h}_{11}& K& h_{1N}\\ M& O& M\\ h_{M1}& L& h_{\mathrm{MN}}\end{array}\right)---\left(1\right)$

Wherein, h _IjIt is the complex gain between i transmitting antenna and j the reception antenna.The mimo system model can be expressed as:

y＝Hx+n (2)

Wherein, x is an emission signal vector, and y is a received signal vector, and n is an Additive White Gaussian Noise, and its average is 0 vector, and variance is η ²

For eliminating or reducing and disturb, make data flow on orthogonal sub-channels, transmit effectively the mimo channel diagonalization, can use the method for channel response matrix being carried out singular value decomposition, be expressed as:

H＝UAV ^H (3)

Wherein, U is the unitary matrice of M * M, and A is the matrix of M * N, and V is the unitary matrice of N * N, [] ^HThe conjugate transpose that refers to matrix.The diagonal element of matrix A is matrix B=H ^HThe eigenvalue of H _i(the square root of 1≤i≤L).

Singular value decomposition is decomposed into two unitary matrice U and V and diagonal matrix A to channel response matrix H, and matrix A has been described the feature mode of mimo channel, corresponding to spatial sub-channel.Be the diagonalization mimo channel, a signal vector s can multiply by matrix U again launching external reservoir with matrix V from mimo channel when receiving ^H, obtain one like this and receive the vectorial r of recovery, be expressed as:

$r=U^H\mathrm{HVs}+U^{H}n$

Like this, mimo channel just is decomposed for L independence, no phase mutual interference, quadrature, parallel channel, i.e. mimo channel spatial sub-channel.The gain of spatial sub-channel i or feature mode i equals eigenvalue _iReceiver is estimated channel response matrix H, feeds back to transmitting terminal then, and H carries out diagonalization to mimo channel thereby transmitting terminal utilizes channel response matrix information, obtains L independent orthogonal spatial sub-channel.

If the total transmitting power of mimo system is P _TThe power distribution method of a maximized system capacity is the power division of pouring water, and promptly whole transmit power allocations is given the spatial sub-channel of L feature mode correspondence, and the channel allocation with bigger mode characteristic values is given higher power.The power of distributing for channel i can be expressed as:

$P_i={[\mathrm{\&mu;}-\frac{N{\mathrm{\&eta;}}^2}{P_T{\mathrm{\&lambda;}}_i}]}^{+},$ Wherein [a] ⁺Expression max (0, a) (5)

Select μ to make

$\underset{i}{\mathrm{\&Sigma;}}{P}_i=P_T---\left(6\right)$

Based on the transmitting power of distributing, then the effective signal-to-noise ratio γ of feature mode i _iFor

${\mathrm{\&gamma;}}_i=\frac{P_i}{{\mathrm{\&eta;}}^2}{\&CenterDot;\mathrm{\&lambda;}}_i---\left(7\right)$

Then the capacity of L spatial sub-channel is

$C=\underset{i=1}{\overset{L}{\mathrm{\&Sigma;}}}{\log }_2(1+{\mathrm{\&gamma;}}_i)---\left(8\right)$

If the spectrum efficiency of each feature mode i is

δ _i=log ₂(1+ γ _i) (9) SNR of establishing the required minimum of spatial sub-channel i is γ _i ^Min, then the required minimum power of spatial sub-channel i is

$P_i^{\min }=\frac{{\mathrm{\&gamma;}}_i^{\min }{\mathrm{\&eta;}}^2}{{\mathrm{\&lambda;}}_i}---\left(10\right)$

In the present embodiment, supposing the system number of transmit antennas N and reception antenna number M are respectively N=M=4, feature mode number L=4, and the feature mode value is respectively λ ₁=4, λ ₂=2, λ ₃=1, λ ₄=0.4.If the peak transmitted power normalization of each transmitting antenna is P _m=1, the total maximum transmission power P of transmitter then _T=4 * 1=4, receiver noise variance η ²=0.05, minimum SNR is γ ^Min=15.8489=12dB supposes that feature mode 2 and 4 has minimum SNR demand.

(1) step of optimal power allocation of the present invention is as follows:

Step 1 characteristic value is known, because L=4, has comprised all feature modes among the set F, i.e. F={1,2,3,4}.

Step 2 set E={2,4} is according to the required minimum power of formula (10) calculated characteristics pattern 2 and 4

P ₂ ^min＝0.3962，P ₄ ^min＝1.9811。

Step 3 judges whether gross power can satisfy minimum power demand

P ₂ ^min+P ₄ ^min＝0.3962+1.9811＝2.3773＜P _T＝4。

Step 4 G={ 1,2,3,4} utilizes the power distribution method of pouring water to calculate according to formula (5) and (6) GIn the power division of each feature mode

P ₁(1)＝1.0406，P ₂(1)＝1.0281，P ₃(1)＝1.0031，P ₄(1)＝0.9281。

Step 5 has judged whether that feature mode does not satisfy the lowest power demand

P ₄(1)＝0.9281＜P ₄ ^min＝1.9811，

Be that feature mode 4 does not satisfy, G={4} then.

Distribute minimum power to give feature mode 4, P ₄(1)=P ₄ ^Min=1.9811.

The residue gross power is P _T=P _T-P ₄(1)=4-1.9811=2.0189.

G＝{1，2，3}，k＝2。

The reallocation of step 6 power

Utilize residue gross power P according to formula (5) and (6) _TGather the power division of pouring water among the G at feature mode, have

P ₁(2)＝0.6896，P ₂(2)＝0.6771，P ₃(2)＝0.6521。

P ₂ ^Min=0.3962＜P ₂(2)=0.6771, distribute the minimal power requirements that satisfies feature mode 2.

Step 7 power division finishes

Optimum allocation power is:

P ₁＝0.6896，P ₂＝0.6771，P ₃＝0.6521，P ₄＝1.9811。

According to formula (7), calculate the corresponding SNR of each feature mode and be respectively:

γ ₁＝55.1680，γ ₂＝27.0840，γ ₃＝13.0420，γ ₄＝15.8488。

According to capacity formula (8), the computing system capacity is

C＝18.5096。

(2) among this embodiment, do not consider that power division of pouring water (WF) and channel capacity that minimum SNR requires are

P ₁＝1.0406，P ₂＝1.0281，P ₃＝1.0031，P ₄＝0.9281。

Corresponding SNR is respectively

γ ₁＝83.2500，γ ₂＝41.1250，γ ₃＝20.0625，γ ₄＝7.4250。

Y ₄＜Y ₄ ^Min, the SNR of feature mode 4 does not satisfy minimum SNR demand.

Power system capacity is

C＝19.2645。

(3) among this embodiment, the power distribution result of additive method one is as follows:

The power that each spatial sub-channel distributes is

P ₁＝0.4463，P ₂＝0.8300，P ₃＝0.4088，P ₄＝2.3149。

The corresponding SNR of each spatial sub-channel is

γ ₁＝35.7040，γ ₂＝33.2000，γ ₃＝8.1760，γ ₄＝18.5192。

Channel capacity is

C＝17.7785。

(4) among this embodiment, the power distribution result of additive method two is as follows:

The power that each spatial sub-channel distributes is

P ₁＝0.8301，P ₂＝0.3962，P ₃＝0.7926，P ₄＝1.9811。

The corresponding SNR of each spatial sub-channel is

γ ₁＝66.4080，γ ₂＝15.8480，γ ₃＝15.8520，γ ₄＝15.8488。

Channel capacity is

C＝18.2988。

The result shows: though the power distribution method of pouring water has the highest channel capacity, can not guarantee the demand on signal quality of the spatial sub-channel of minimum SNR; The optimal power allocation method that the present invention provides has realized at the preferred channels capacity that guarantees under the condition that minimum SNR requires.

Claims (8)

1, the power distribution method that ensures signal quality in a kind of multi-channel multi-antenna communication system is characterized in that, may further comprise the steps:

The power division of on all feature modes, pouring water;

If exist the power that distributes less than the feature mode that satisfies the required minimum power of minimum signal to noise ratio, just minimum power demand is distributed to this feature mode, in remaining feature mode set, use the power division of pouring water with remaining gross power then;

If distribute power to satisfy each feature mode minimal power requirements, then distribute to finish, otherwise continue to utilize the rule of pouring water to carry out power division.

2, the power distribution method that ensures signal quality in the multi-channel multi-antenna communication system according to claim 1 is characterized in that, further may further comprise the steps:

Step 1: initialization maximum transmission power P _TWith channel response matrix H, carry out feature mode and decompose, determine eigenvalue and treat the feature mode set F of power division, set G=Φ, set G=F-G, iterations k=0; H is carried out feature mode decompose, then forming set F greater than zero feature mode;

Step 2: define the feature mode subclass E that minimum signal to noise ratio requires, calculate the required minimum power P of each feature mode among the E _i ^MinIn feature mode set F, select to form feature mode subclass E, each feature mode power demand P among the subset of computations E greater than zero element by the minimum snr value that minimum signal to noise ratio requires or requires _i ^Min

Step 3: if $\underset{i\&Element;E}{\mathrm{\&Sigma;}}{P}_i^{\min }\&le;P_T,$ Change step 5; Otherwise change step 4;

Step 4: if $\underset{i\&Element;E}{\mathrm{\&Sigma;}}{P}_i^{\min }>P_T,$ Then, remove subchannel one by one, enough distribute other to give the spatial sub-channel of minimum signal to noise ratio requirement up to gross power with minimal characteristic mode value according to feature mode ordering from big to small among the subclass E; Upgrade the feature mode set F of power to be allocated, have $\underset{i\&Element;F}{\mathrm{\&Sigma;}}{P}_i^{\min }\&le;P_T,$ Change step 5;

Step 5:k=k+1, set GIn, at gross power P _TThe following use power distribution method of pouring water is that each feature mode distributes power P _i(k);

Step 6: if P is all arranged for each feature mode among the set E _i(k) 〉=P _i ^Min, then change step 9; Otherwise change step 7;

Step 7: set GIn satisfy P _i(k)≤P _i ^MinFeature mode add set G, distribute power to make that wherein the power of each feature mode is minimum power, i.e. P for set G _j(k)=P _j ^Min(j ∈ G); Then total surplus power is $P_T=P_T-\underset{j\&Element;G}{\mathrm{\&Sigma;}}{P}_j^{\min },$ Upgrade set G

Step 8: if G=Φ then changes step 9; Otherwise change step 5;

Step 9: the power division process finishes.

3, the power distribution method that ensures signal quality in the multi-channel multi-antenna communication system according to claim 2, it is characterized in that, in described step 1, at first require required power, the power division of then dump power being poured water on all spatial sub-channels for the spatial sub-channel basic of distribution signal to noise ratio that has minimum signal to noise ratio to require.

4, the power distribution method that ensures signal quality in the multi-channel multi-antenna communication system according to claim 2, it is characterized in that, in described step 1, at first be that the channel allocation that has minimum signal to noise ratio to require requires required power according to signal to noise ratio, the power division of then dump power being poured water on all the other spatial sub-channels that do not have minimum signal to noise ratio to require.

5, the power distribution method that ensures signal quality in the multi-channel multi-antenna communication system according to claim 1 is characterized in that, further may further comprise the steps:

Step 1: initialization maximum transmission power P _TWith channel response matrix H, carry out feature mode and decompose, determine eigenvalue and treat the feature mode set F of power division, initial sets G=B=Φ, set Z=F-(G ∪ B), iterations k=0; H is carried out feature mode decompose, then forming set F greater than zero feature mode;

Step 2: define the feature mode subclass E that minimum signal to noise ratio requires, calculate the required minimum power P of each feature mode among the E _i ^MinDefine the feature mode subset D of maximum signal to noise ratio requirement, calculate the required maximum power P of each feature mode among the D _j ^MaxIf the set F in all feature modes all have the maximum signal to noise ratio requirement and $\underset{i\&Element;F}{\mathrm{\&Sigma;}}{P}_i^{\max }<P_T,$ Then make maximum transmission power be $P_T=\underset{i\&Element;F}{\mathrm{\&Sigma;}}{P}_i^{\max };$

Step 3: if $\underset{i\&Element;E}{\mathrm{\&Sigma;}}{P}_i^{\min }\&le;P_T,$ Change step 5; Otherwise, change step 4;

Step 4: if $\underset{i\&Element;E}{\mathrm{\&Sigma;}}{P}_i^{\min }>P_T,$ Then, remove subchannel one by one, enough distribute other to give the spatial sub-channel of minimum signal to noise ratio requirement up to gross power with minimal characteristic mode value according to feature mode ordering from big to small among the subclass E; Upgrade the feature mode set F of power to be allocated, have $\underset{i\&Element;F}{\mathrm{\&Sigma;}}{P}_i^{\min }\&le;P_T,$ Change step 5;

Step 5:k=k+1 is among the set Z, at gross power P _TThe following use power distribution method of pouring water is that each feature mode distributes power P _i(k);

Step 6: if P is all arranged for each feature mode among the set E _i(k) 〉=P _i ^Min, and each feature mode among the set D all has P _j(k)≤P _j ^Max, then change step 9; Otherwise change step 7;

Step 7: satisfying P among the set Z _i(k)＜P _i ^MinFeature mode add set G, distribute power to make that wherein the power of each feature mode is minimum power, i.e. P for set G _i(k)=P _i ^Min(i ∈ G); Satisfying P among the set Z _j(k)＞P _i ^MaxFeature mode add set B, distribute power to make that to set B wherein the power of each feature mode is maximum power, i.e. P _j(k)=P _j ^Max(j ∈ B); Then total surplus power is $P_T=P_T-\underset{i\&Element;G}{\mathrm{\&Sigma;}}{P}_i^{\min }-\underset{j\&Element;B}{\mathrm{\&Sigma;}}{P}_j^{\max },$ Upgrade set Z;

Step 8:, then change step 9 if Z=is Φ; Otherwise change step 5;

Step 9: the power division process finishes.

6, the power distribution method that ensures signal quality in the multi-channel multi-antenna communication system according to claim 5, it is characterized in that, in described step 1, at first require required power, the power division of then dump power being poured water on all spatial sub-channels for the spatial sub-channel basic of distribution signal to noise ratio that has minimum signal to noise ratio to require.

7, the power distribution method that ensures signal quality in the multi-channel multi-antenna communication system according to claim 5, it is characterized in that, in described step 1, at first be that the channel allocation that has minimum signal to noise ratio to require requires required power according to signal to noise ratio, the power division of then dump power being poured water on all the other spatial sub-channels that do not have minimum signal to noise ratio to require.

According to the power distribution method that ensures signal quality in claim 2 or the 5 described multi-channel multi-antenna communication systems, it is characterized in that 8, described Φ is an empty set.

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