CN101868018B - Method for allocating low-bit feedback user frequencies of MIMO - Google Patents

Abstract

The invention discloses a method for allocating low-bit feedback user frequencies of MIMO, which comprises the following steps of: firstly, defining serial numbers embodying power allocation priority for user antennae, and acquiring all serial number arrangements of all the antennae through permutation and combination; secondly, sending test signals by a base station, giving a serial number to each antenna by a user according to a rule that the greater the signal-to-noise ratio is the higher the priority is, feeding serial number information and the maximum value and the minimum value of the signal-to-noise ratio back to the base station, calculating the mean value of the signal-to-noise ratio by the base station, and selecting a user according to the mean value to perform power allocation for the first time; and finally, performing the power allocation on each antenna for the second time by the base station according to the fed back serial number information and a rule that the higher the priority of the serial number of the antenna is the higher the allocated power of the antenna is. The method overcomes the defect that the conventional user subchannel estimation needs oversize feedback information quantity, can effectively estimate the basic states of all the subchannels of the user under the condition of decreasing the feedback information quantity to perform reasonable user power allocation, improves the transmission performance, and increases the data transmission throughput.

Description

A kind of low-bit feedback user power distribution method that is used for MIMO

Technical field

The present invention relates to multiple-input and multiple-output (MIMO) communications field, be specifically related to the low-bit feedback user power distribution method of a kind of MIMO of being used for.

Background technology

In the MIMO communication system; It disposes many antenna elements at transmitting-receiving two-end, through time-space Combined Treatment technology, with the multipath transmisstion that is considered to usually in the radio transmission be harmful to; Change the multipath delay expansion useful into, thereby improved transfer rate the user.

But for reaching optimum dirty paper code (DPC) transmission plan of capacity in theory, because its coding and decoding complexity is too high and too tight to the requirement of channel information precision, but its practicality is very low in the mimo system.Follow-up researcher also studies for the lower suboptimum transmission plan of complexity; And close-to zero beam forms technology (ZFBF); According to research, like A.Goldsmith et al. " On the optimality of multiantenna broadcast scheduling using zero-forcing beamforming ", IEEE Journal on Selected Area of Comm.; Vol.24; No.3, March 2006 is said, the upper limit that can under the more situation of number of users, approach throughput in the mimo system with lower processing complexity.Yet this method needs all users in each all antenna subchannel information of time slot feedback, selects and power division to carry out rational user.Can bring very big feedback overhead to the user like this, and because number of users is a lot, the complexity of base station selected user's set is very high.

Summary of the invention

The object of the present invention is to provide the low-bit feedback user power distribution method of a kind of MIMO of being used for; This method has reduced the bit number that the user need feed back; Shorten the time of base station selected transmission user set, improved transmission performance, improved the transfer of data throughput.

A kind of low-bit feedback user power distribution method that is used for MIMO is specially:

(1) each user confirms the antenna number set of self:

(1.1) self-defined n different antennas numbering, numbering should embody the priority level that antenna power distributes, and n is this user's a antenna number;

(1.2) n antenna number done permutation and combination, obtain the antenna number set A _User={ a _i, i=1,2..., 2n! , arrange a for i _iJ the numbering that element is a j root antenna;

(2) all users' of base station stored antenna number set;

(3) all antenna transmission test signals of all users are given in the base station;

(4) each user acceptance test signal, and operation as follows:

(4.1) big more according to the signal to noise ratio of receiving signal to each antenna, the high more criterion of priority that this antenna power distributes is given the numbering of step (1.1) definition;

(4.2) the sequence number z of the numbering result that obtains of query steps (4.1) in this user's antenna number set;

(4.3) to base station feedback sequence number z, maximum signal to noise ratio S _{U_max}With minimum signal to noise ratio S _{U_min}

(5) handle according to following mode each user's feedback the base station:

(5.1) calculate signal to noise ratio intermediate value S _{U_aver}=(S _{U_max}+ S _{U_min})/2;

(5.2) if signal to noise ratio intermediate value S _{U_aver}Greater than threshold value S _Thresh, then distribute power P for this user _u, get into step (5.3), otherwise, do not distribute this user power, finish;

(5.3) base station is searched antenna number and is arranged a in this user's antenna number set _z, with power P _uPriority according to antenna number is high more, and the high more criterion of the power of this antenna assignment is distributed to each antenna.

The present invention's advantage compared with prior art is: at D.A.Gore et al. " Transmit selection in spatial multiplexing systems "; IEEE Comm.Letters; Vol.6, No.11 is among the Nov.2002; The signal to noise ratio that analysis obtains all subchannels is the stochastic variable of obeying card side's distribution (Chisquared distributed), and the signal to noise ratio of channel is the key factor that influences channel information.This is the appropriate design feedback scheme just, and simplifying scheduling processing method provides theoretical foundation.The present invention has confirmed the scope of the channel condition information (CSI) of each subchannel of user through at user side all subchannel SNR being sorted; End user terminal only feeds back maximum, minimum value and the antenna alignment sequence number of all subchannel SNR, and having reduced user side greatly needs the feedack amount, has reduced feedback overhead; And base station end only need be calculated the essential information that the intermediate value of all subchannel SNR of each user feedback just can obtain the subscriber channel state, thereby has reduced the complexity of base station end selection transmission user, reasonably carries out power division; Simultaneously, carry out secondary distribution, can on the basis that guarantees user's key property, further improve user's overall performance, also guaranteed the flexibility that sub-channel power is distributed simultaneously according to user's antenna alignment sequence number.

Description of drawings

Fig. 1 is the inventive method flow chart;

Fig. 2 is for when user's maximum antenna number is 3 to 10, and the bit number and the tradition that adopt the present invention to feed back need the ratio sketch map between the needed bit number of the whole user's subchannel SNR of feedback.

Embodiment

Below in conjunction with the practical implementation example to further explain of the present invention.

Present embodiment adopts K=20 user's descending multi-user mimo system.Base station end configuration M=12 root antenna, the user disposes 3～5 antennas and does not wait.Suppose that user antenna can be decomposed into independently subchannel through precoding processing, each subchannel is obeyed card side and is distributed.

(1) each user confirms the antenna number set:

With the user 4 antennas being arranged is example, defines four antenna numbers and is respectively 1,2,3,4, and wherein the 1 expression antenna power priority of distributing is minimum, and 2 are higher than 1,3, and to be higher than 2,4 priority the highest.User antenna is arranged set A _User={ a ₁, a ₂..., a ₄₈, a ₁=(1,2,3,4), a ₂=(1,2,4,3) ..., arrange a for i _iJ the numbering that element is a j root antenna, i=1,2..., 48.

(2) all users' of base station stored antenna number set;

(3) all antenna transmission test signals of all users are given in the base station;

(4) each user acceptance test signal, and operation as follows:

The user receives signal according to every antenna SNR to the sky line ordering, supposes that the user has 4 antennas by descending, and the SNR that four antennas of first antenna to the receive is followed successively by { 10dB; 8dB, 11dB, 3dB}; Big more according to the Signal-to-Noise of receiving to first to the 4th antenna, the high more criterion of priority that another day, linear heat generation rate distributed is given numbering successively and is obtained { 3,2; 4,1}.The user at first searches the antenna alignment set, and { 3,2,4, it is 140 that the 1} corresponding antenna is arranged sequence number to obtain numbering.And the maximum 11dB of recording user subchannel SNR and minimum value 3dB.The user sends to the base station with maximum 11dB, minimum value 3dB and the antenna alignment sequence number 140 of SNR.

(5) base station end is carried out user's selection and the power division first time.

Explain with step (4) example:

(5.1) the intermediate value processing is carried out according to maximum and the minimum value of the next SNR of user feedback in the base station, promptly $S_{u\_\mathrm{Aver}}=(11\mathrm{DB}+3\mathrm{DB})/2=\sqrt{11.3}\mathrm{DB}\≈5.7\mathrm{DB}.$

(5.2) base station is according to user's intermediate value S _{U_aver}=5.7dB carries out user's selection, its intermediate value greater than threshold value (generally get 3～5dB), then this user is selected, the base station with choose the user to communicate.

At first to carry out power division when the base station communicates these users that choose, can adopt water-filling algorithm (promptly according to user's S to the user _{U_aver}Size distribute power, S _{U_aver}Little distribution power is few, S _{U_aver}Big distribution power is big) realize the maximization of subscriber channel capacity.S _{U_aver}The power that the user of=5.7dB is assigned with is 1mW.

(6) the power division second time is carried out according to the antenna alignment sequence number of selected user in the base station

Explain with step (4) example equally:

(6.1) base station is arranged sequence number a to selected user in its antenna number set search corresponding antenna ₁₄₀

(6.2) carry out the subchannel user power according to the user antenna number and quantize, quantification manner is:

Wherein, k _iFor arranging sequence number a according to user antenna _iThe numeral number that the i root antenna of finding is corresponding.In the instance, n=4, P _u=1mW, according to such allocation strategy, four antenna assignment of user to power is respectively $\{1\mathrm{MW}\·\frac{3}{3+2+4+1},1\mathrm{MW}\·\frac{2}{3+2+4+1},1\mathrm{MW}\·\frac{4}{3+2+4+1},1\mathrm{MW}\·\frac{1}{3+2+4+1}\},$ I.e. { 0.3mW, 0.2mW, 0.4mW, 0.1mW}.This quantification manner demonstrates fully the user power of distributing for the first time high more according to the priority that antenna number embodies; The high more criterion of the power of this antenna assignment is distributed to each antenna; The concrete method of salary distribution is not limited to this, all can as long as satisfy any way of this principle.

During greater than 3, the bit number that this feedback method need feed back will be less than the needed bit number of SNR that needs all antenna subchannels of feedback user at selecteed certain user's antenna.And the ratio of the bit number of the bit number of this method feedback and original method feedback can reduce along with the increase of user antenna number.Fig. 2 represent when user's number of antenna when 3 rise to 10, the variation of the bit number ratio that two kinds of methods need be fed back.

The numbering form of definition is not limited to the digital form in the instance, can adopt for example letter of other any form, and key point is to want the priority level relation of clear and definite each numbering.

Claims (1)

1. low-bit feedback user power distribution method that is used for MIMO is specially:

(1) each user confirms the antenna number set of self:

(1.1) self-defined n different antennas numbering, numbering should embody the priority level that antenna power distributes, and n is this user's a antenna number;

(1.2) n antenna number done permutation and combination, obtain the antenna number set A _User={ a _i, i=1,2..., 2n! , arrange a for i _iJ the numbering that element is a j root antenna;

(2) all users' of base station stored antenna number set;

(3) all antenna transmission test signals of all users are given in the base station;

(4) each user acceptance test signal, and operation as follows:

(4.1) big more according to the signal to noise ratio of receiving signal to each antenna, the high more criterion of priority that this antenna power distributes is given the numbering of step (1.1) definition;

(4.2) the sequence number z of the numbering result that obtains of query steps (4.1) in this user's antenna number set;

(4.3) receive the maximum signal to noise ratio S of signal to base station feedback sequence number z, antenna _{U_max}With minimum signal to noise ratio S _{U_min}

(5) handle according to following mode each user's feedback the base station:

(5.1) calculate signal to noise ratio intermediate value S _{U_aver}=(S _{U_max}+ S _{U_min})/2;

(5.2) if signal to noise ratio intermediate value S _{U_aver}Greater than threshold value S _Thresh, then distribute power P for this user _u, get into step (5.3), otherwise, do not distribute this user power, finish;

(5.3) base station is searched antenna number and is arranged a in this user's antenna number set _z, with power P _uPriority according to antenna number is high more, and the high more criterion of the power of this antenna assignment is distributed to each antenna.

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