CN101656601B - Method, unit and processor for feeding back information in communication system - Google Patents

Abstract

The invention discloses a method for feeding back information in a communication system. The method comprises the following steps: selecting a limited number of K' frequency subbands and a limited number of P precoding matrixes corresponding to the limited number of K' frequency subbands at a receiving end, wherein the K' frequency subbands are contained in a subset omega (from m1 to mK') of the set omega, K' is smaller than K, and P is equal to 1; and transmitting information for recognizing the subset omega and a precoding matrix index for recognizing the precoding matrixes to a transmitting end.

Description

The method of feeding back information in communication system, unit and processor

Technical field

The present invention relates to a kind of method at feeding back information in communication system, receiving element, transmitter unit and processor.

Background technology

Transmitter and receiver is all used the wireless telecommunication system of many antennas to be commonly called multiple-input, multiple-output (MIMO) system.As everyone knows, in the prior art, if use linear MIMO precoding in transmitter-side, systematic function will be greatly improved.This linear predictive coding of IEEE 802.16-2005 standard executed, and advised adopting this linear predictive coding in 3GPP E-UTRA standard.

In conjunction with the OFDM after MIMO (OFDM), can make MIMO precoding expand on Frequency-Selective MIMO Channel.In MIMO-OFDM system, broad-band channel is converted into and the corresponding a plurality of narrow band channels of OFDM subcarrier.Can suppose that each narrow band channel is for flat fading.

And adjacent OFDM subcarrier forms the impartial group of size, obtains OFDM frequency sub-band.In 3GPP E-UTRA, commonly every 25 adjacent OFDM subcarriers form an OFDM frequency sub-band.Like this, total bandwidth can be divided into K frequency sub-band.The width that each frequency sub-band is set is approximately flat fading to guarantee the channel in frequency sub-band.This represents that same best pre-coding matrix generally can be used for all subcarriers of same frequency sub-band.

MIMO-OFDM system has produced a problem: due to frequency selective scheduling, channel quality is the function of a plurality of OFDM frequency sub-band, has therefore increased feedback overhead.In addition, when adopt based on code table (codebook) linear MIMO precoding time, receiver need to be pointed out to code table the pre-coding matrix index (PMI) of each OFDM frequency sub-band.This load that just means signaling consumption obviously increases, and must find a kind of method that reduces expense.

For the precoding MIMO-OFDM based on code table, existing background technology is all utilized the correlation between the best pre-coding matrix of adjacent subcarrier or frequency sub-band, reduces the feedback quantity of precoding information.

Last in the application, with the reference paper list of background technology.

At reference paper [6] (3GPP R1-061441, " Feedback Reduction for Rank-1pre-coding for E-UTRA downlink ", Texas Instruments, Shanghai, May 2006 (3GPP R1-061441, " first order precoding feedback reduction method of E-UTRA down link ", Texas Instrument, Shanghai, and reference paper [7] (3GPP R1-061439 in May, 2006)), " Evaluationof Codebook-based Precoding for LTE MIMO Systems ", Texas Instruments, Shanghai, May 2006 (3GPP R1-061439, " the precoding assessment based on code table in LTE mimo system ", Texas Instrument, Shanghai, in May, 2006)) in, a kind of group technology has been described, by setting up larger adjacent sub-carrier group, find out in larger group on average all efficient precoding matrixes, thereby reduced precoding information feedback.For example, recommend every two OFDM frequency sub-band to use a pre-coding matrix index in reference paper [6], compare with a pre-coding matrix index of each OFDM frequency sub-band feedback, systematic function declines only slightly.And adopt in this way, the feedback overhead of pre-coding matrix just can reduce by half.

At reference paper [3] (J.Choi, R.W.Heath Jr., " Interpolation Based UnitaryPrecoding for Spatial Multiplexing MIMO-OFDM with Limited Feedback ", IEEE Globecom Conference 2004, Dallas, USA, November 2004, page 214-218 (J.Choi and R.W.Heath Jr., " the interpolation monobasic precoding of Limited Feedback in spatial multiplexing MIMO-OFDM ", IEEE international communication seminar document assembly in 2004, Dallas, the U.S., in November, 2004, and reference paper [4] (J.Choi 214-218 page)), R.W.Heath Jr., " InterpolationBased Transmit Beamforming for MIMO-OFDM with Limited Feedback ", IEEETransactions on Signal Processing, Vol.53, No.11, November 2005, page4125-4135 (J.Choi and R.W.Heath Jr., " in MIMO-OFDM, the interpolation of Limited Feedback sends beam forming method ", IEEE signal is processed journal, the 53rd volume o.11, in November, 2005, the method of same principle has also been proposed 4125-4135 page)).The author of reference paper proposes to report the pre-coding matrix index of every L OFDM subcarrier, and subcarrier is sampled and selected in whole bandwidth here.At transmitter, by interpolation arithmetic, middle pre-coding matrix index is reconstructed.

At reference paper [5] (B.Mondahl, R.W.Heath Jr., " Algorithms for QuantizedPrecoding in MIMO-OFDM Beamforming Systems ", Proceedings of the SPIE, Volume 5847, pp.80-87, 2005 (B.Mondahl and R.W.Heath Jr., " the quantification precoding algorithm in MIMO-OFDM Beam Forming System ", SPIE committee paper compilation, the 5847th volume, 80-87 page, 2005)) in, another kind of method has been proposed, according to this method, quantized channel information in time domain rather than in frequency domain (pre-coding matrix information), this conversion has been carried out decorrelation to channel information.The essence of this method is, decorrelation pre-coding matrix information before quantizing.The group technology that the effect of this method and reference paper [4] provide is similar.

The existing method for reducing precoding matrix index feedback signaling amount has a common defect, and that is exactly their often feedback information useless to system transmitting terminal.The existing solution for reducing precoding matrix index feedback expense is not all considered in some information of transmitting terminal important, and other information are so unimportant.

Therefore, need to find out a kind of method, can select intelligently should feedack, to further reduce precoding matrix index feedback signaling consumption amount.

Summary of the invention

The object of the present invention is to provide a kind of method for receiving terminal of communication system and transmitting terminal, to reduce precoding feedback amount of information.The present invention is also provided for a kind of receiving element in said system, a kind of transmitter unit and a kind of processor, for matrix index feedback signaling is limited within the scope of system Useful Information.

For realizing object of the present invention, the invention provides the method with feature described in claim 1 to 7, for reducing precoding feedback amount of information.

For realizing object of the present invention, the present invention also provides the transmitter unit that has the receiving element of feature described in claim 8 to 9 and have feature described in claim 10 to 11, for reducing precoding feedback amount of information.

Which information the method that the application of the invention provides, receiving element, transmitter unit and processor, can effectively judge at receiver useful to transmitter, and feed back these information.

The method that the application of the invention provides, receiving element, transmitter unit and processor, can no longer be wasted in the communication resource on second-rate frequency sub-band signaling information.

Therefore, method provided by the invention, receiving element, transmitter unit and processor limits feedback information only include can be scheduled, the frequency sub-band information for transmitting.Therefore feedback information volume reduces.

The invention provides a solution, between throughput of system and reduction feedback information volume, found good balance point.

In embodiments of the present invention, the number of elements in precoding code table index vector can be set to a low value, as is made as 1.This can effectively reduce feedback signaling amount.When the performance of pre-coding matrix and OFDM frequency sub-band height correlation, the embodiment of the present invention is also favourable.

Below with reference to the preferred embodiment diagram in accompanying drawing, describe the method for reducing matrix index feedback signaling amount provided by the invention, receiving element, transmitter unit and processor in detail, and the advantage of described method, receiving element, transmitter unit and processor.

Accompanying drawing explanation

Fig. 1 has shown the subset ω selecting from all available frequency sub-band Ω, and identifies ω with bitmap B.

Fig. 2 has shown the subset ω that Ω selects from all available frequency sub-band, and at (a) with (b), subset ω is used to group technology.

Fig. 3 has shown the SNR curve chart example of pre-coding matrix and frequency sub-band in OFDM frequency sub-band frequency spectrum.

Fig. 4 has shown another SNR curve chart example of pre-coding matrix and frequency sub-band in OFDM frequency sub-band frequency spectrum.

Embodiment

There is N _tindividual transmitting antenna and N _rin the flat fading of individual reception antenna, non-precoding MIMO system, its Input output Relationship can be described below:

y＝Hx+n.(1)

In formula (1), x is the N that has sent symbol _t* 1 vector, y, n is respectively the N of receiving symbol and noise _r* 1 vector, H is the N of channel coefficients _r* N _tmatrix.Send symbol and on mimo channel H, carried out N _tinferior spatial reuse, that is to say, N _tindividual data flow is by parallel transmission, and its spectrum efficiency can reach N in theory _tdoubly.

Linear predictive coding represents: in formula (1), introduced N _t* N _spre-coding matrix W, for carrying out precoding to the symbol of vector x.Columns N _scan be set to be less than line number N _t, at this moment x is revised as N _s* 1.Like this, N _sthe capable transmission of individual data levelling, is called rank adaptation (rank adaptation), and it is less that this is illustrated on channel the symbol of spatial reuse.Although the symbol of spatial reuse is less, the error rate of is-symbol has reduced, so rank adaptation is useful.The Input output Relationship of precoding MIMO is described below:

y＝HWx+n.(2)

In formula (2), select best pre-encoder matrix W, just need to understand the statistic of channel H and receiver noise.Because receiver is easy to obtain these information, so this selection course is preferably carried out by receiver.Then receiver issues transmitter by the precoder W choosing, and transmitter carries out precoding according to the selection of receiver.In order to reduce the signaling traffic load between Receiver And Transmitter, conventionally suppose that this pre-coding matrix W belongs to a fixing pre-coding matrix set, this fixing pre-coding matrix set is here called code table.If there be N element in code table, only need bit represents an element in code table, so receiver only need to be issued transmitter by pre-coding matrix index (PMI).

In conjunction with the OFDM after MIMO, making MIMO precoding expand to frequency selects on property mimo channel.In MIMO-OFDM system, broad-band channel is converted into and the corresponding a plurality of narrow band channels of OFDM subcarrier.Can suppose that each narrow band channel is flat fading.Use after OFDM, formula (1) and (2) just can be used on all described narrow band channels.

And adjacent OFDM subcarrier forms the impartial group of size, obtains OFDM frequency sub-band.In 3GPPE-UTRA, commonly every 25 adjacent OFDM subcarriers form an OFDM frequency sub-band.Like this, total bandwidth can be divided into K frequency sub-band.The width that each frequency sub-band is set is approximately flat fading to guarantee the channel in frequency sub-band.Best pre-coding matrix W in this representation formula (2) generally can be used for all subcarriers of same frequency sub-band.Therefore, in PMI feedback, minimum necessary unit is a frequency sub-band, and each frequency sub-band only need to feed back a PMI.

In ofdm system, carry out frequency selective scheduling.In systems such as E-UTRAN and IEEE 802.16, due to channel quality, as signal interference ratio, on whole transmission bandwidth, change, therefore can the scheduling of proportion selectivity and multi-subscriber dispatching.

In order to realize frequency selective scheduling, receiver is indicated on feedback channel, and all in K OFDM frequency sub-band, which Q frequency sub-band is more suitable in receiving data, and provides the CQI of this Q frequency range.In all K OFDM frequency sub-band, receiver can be selected Q the frequency sub-band that signal interference ratio is the highest naturally.This point is as the reference paper of prior art [1] " 3GPP R1-061246 " Unifieduplink CQI signalling by efficient labeling "; Huawei; Shanghai; May 2006 " (" realizing unified up link CQI signaling by effective label ", Huawei, Shanghai, 2006) shown in.

Prior art reference paper [2] " PCT/CN/2006/0004; " Method for sub-bandindicator signalling "; Huawei; Patent application; March 2006 " (PCT/CN/2006/0004, < < frequency sub-band designator Signalling method) > >, Huawei, patent application, in March, 2006) further provided a kind of effective method, for the subset that represents to be formed by a K available frequency sub-band Q frequency sub-band.

The method that the present invention adopts combines the behavior of physical layer precoding and the action of dispatch layer.What therefore, the present invention adopted is cross-layer method.

The present inventor observes, and due to the competition between user, the user on the OFDM frequency sub-band of bad channel quality can not be scheduled.

The present inventor further finds, the OFDM frequency sub-band that each channel quality is high has relevant pre-coding matrix index.This just means on a high-quality frequency sub-band and shows good pre-coding matrix, probably on another high-quality frequency sub-band, also can show good.Inventor thinks that this discovery can be used for reducing the quantity of the pre-coding matrix using.

Therefore, there is no need to feed back the pre-coding matrix information of all OFDM frequency sub-band, because transmitter does not need to use this information, unless all frequency sub-band are all scheduled, to user, use, and in this case, just do not have frequency scheduling gain to say at all.

The present invention and prior art reference paper [3], [4], [5], [6] and [7] are all different, the present invention is not intended to describe pre-coding matrix indexes all in whole bandwidth, but only describe, channel quality is high, the pre-coding matrix index of the OFDM frequency sub-band that may carry out transformation task.

The label technique providing by reference to file [1], can express the frequency range that receiver is wished scheduling effectively, and preferably, precoding matrix indicators communication (signalling) is consistent with the communication of channel quality information.

OFDM bandwidth can be divided into the frequency sub-band that frequency bandwidth is equal, and wherein K sub-frequency can be for scheduling.The set of this K frequency sub-band represents with Ω.Receiver determines to be that a less subset ω generates a pre-coding matrix index report, and subset ω comprises the individual frequency sub-band of K ' in all K frequency sub-band in Ω here.

By bitmap B, can generate the label of a unique definition set ω.As shown in Figure 1, whole bandwidth is divided into K=12 frequency sub-band, and wherein K '=4 frequency sub-band is selected, and by bitmap mask, B is labelled.Here can also adopt a kind of effective bits compression method, details are referring to reference paper [1] and [2].

Can be the subset ω generating pre-coding matrix index report of OFDM frequency sub-band now.As shown in Figure 2, adopt the subset ω of K '=4 frequency sub-band, precoding information is compressed effectively.Can also adopt group technology as shown in (a) or the method for the single pre-coding matrix index of whole subset ω as shown in (b) further to compress the pre-coding matrix information in ω.

According to the present invention, can select by an optimal standards subset ω of the individual frequency sub-band of K ':

$\{\mathrm{\&Pi;},\mathrm{\&omega;}\}=\arg \underset{\widehat{\mathrm{\&Pi;}}\widehat{\mathrm{\&omega;}}}{\max }f(\widehat{\mathrm{\&Pi;}},\widehat{\mathrm{\&omega;}},N_S)---\left(3\right)$

Wherein П be vector, comprise with vectorial ω in the corresponding pre-coding matrix index of frequency sub-band, the element in ω is selected from Ω here, and ω has formed the complete or collected works of usable frequency frequency sub-band.In addition N, _sthe order of transmission, the i.e. number of transmitting data stream.F is scalar metric function, for a plurality of data flow and a plurality of frequency sub-band metric are mapped to single real number.

In embodiments of the present invention, find out the individual optimum frequency band of K ', make metric function f maximum in formula (3), each frequency range is used its best pre-coding matrix index here, and K ' is set-point.In the present embodiment, П comprises P element, and P value can be as big as the number K ' of selected frequency sub-band here.In the present embodiment, can select a different pre-coding matrix index for the individual frequency sub-band of each K ' in ω.Can find the individual pre-coding matrix index of as many as P=K ', and one group of individual frequency sub-band of K ' in vectorial ω is to meet the formula (3) in the present embodiment.

In another embodiment of the present invention, in order further to reduce feedback information volume, select a vectorial П, make the pre-coding matrix index number comprising in vectorial П be less than the element number in corresponding frequency sub-band vector ω.For example,, by the frequency sub-band grouping in vectorial ω, for every group of frequency sub-band reports a pre-coding matrix index.Although be to divide into groups in the frequency sub-band ω selecting, rather than to all frequency sub-band Ω groupings, this group technology is similar to the method in background technology reference paper [6] herein.In this embodiment, П comprises P element, and the number of P is less than selected frequency sub-band number K ' here.Can find the individual pre-coding matrix index of as many as P < K ', and one group of individual frequency sub-band of K ' in vectorial ω is to meet the formula (3) in the present embodiment.Referring to the example in Fig. 2 (a), here P=2.

In another embodiment of the present invention, in the vectorial П of pre-coding matrix index, only contain an element.In this embodiment, П comprises P=1 element.Therefore, in this embodiment, can find a pre-coding matrix index, and one group of individual frequency sub-band of K ' in vectorial ω is to meet the formula (3) in the present embodiment.Referring to the example in Fig. 2 (b).

Fig. 3 is signal to noise ratio (SNR) the curve chart example of pre-coding matrix and frequency sub-band in OFDM frequency sub-band frequency spectrum.Below how the diagram shows in use Fig. 3 is selected to the combination of pre-coding matrix index and frequency sub-band according to the present invention.

According in first example of the present invention shown in Fig. 3, the number of elements P=1 in П is set, frequency sub-band quantity K '=4 that select.According to method provided by the invention, travel through all possible matrix index and frequency sub-band combination, in this embodiment, specifically to find out an energy and obtain the matrix of optimum performance on four frequency sub-band, and find out the frequency sub-band that four these matrixes will be applied.Here, matrix 3 and frequency sub-band 4,5,6 and 12 are selected.

According in second example of the present invention shown in Fig. 3, be set to P=2, K '=4.The matrix of selecting in this embodiment and frequency sub-band are different from embodiment 1, and what choose is matrix 1 frequency sub-band 7, and no longer comprises frequency sub-band 12.This be because the present embodiment in need to select two matrixes, and the signal to noise ratio of matrix 1 in frequency sub-band 7 higher than matrix 3 signal to noise ratio in frequency sub-band 12.

The existing method that reduces pre-coding matrix index signaling amount in background technology comprises: be a fixed subset of frequency sub-band, as every two frequency sub-band send pre-coding matrix index.The problem of doing is like this that some are second-rate, the frequency sub-band of the program scheduler that can not be scheduled has taken a large amount of pre-coding matrix index signalings.Therefore the method, providing in prior art is unsatisfactory.

In an example shown in Fig. 3, use method of the prior art, with every two frequency sub-band, use the fixed subset of a frequency sub-band, comprise frequency sub-band 1,3,5,7,9 and 11.According to method of the prior art, then for above-mentioned each frequency sub-band, select most probable pre-coding matrix exactly, and the pre-coding matrix of selecting for each frequency sub-band sends pre-coding matrix index signaling.As shown in Figure 3, which matrix no matter frequency sub-band 1,3 and 11 use, and signal to noise ratio is all very poor, and these frequency sub-band generally can not be used to transmitting and scheduling.In the solution of prior art, the related signaling that sends these frequency sub-band has been wasted communication resources.

According to the present invention, once select pre-coding matrix index and one group of individual frequency sub-band of K ' according to formula (3), just can select frequency sub-band and the best of breed of the pre-coding matrix index that uses on frequency sub-band.Here given available pre-coding matrix index number and the value of K ', just can find out pre-coding matrix index and one group of individual frequency sub-band of K ' according to formula (3).

This is because formula (3) travels through all available frequency sub-band and pre-coding matrix index combination, selects the combination that makes function f maximum.Function f provides the measured value of transmission quality.What therefore, formula (3) was selected is the combination that can bring high-transmission quality.What equally, formula (3) was selected is also the combination of the most possible scheduling of scheduler program.Below will further illustrate function f.

Fig. 4 is another example of signal to noise ratio (SNR) curve chart of pre-coding matrix and frequency sub-band in OFDM frequency sub-band frequency spectrum.As shown in Figure 4, some time, some pre-coding matrixes are better than other pre-coding matrix.At this moment, pre-coding matrix index vector П only comprises an element, and embodiment during P=1 especially has superiority in application.Because this pre-coding matrix is all almost best pre-coding matrix in whole bandwidth.When P=1, method of the present invention can be reduced to only chooser frequency range.

The selection of frequency sub-band and pre-coding matrix can also further expand to rank adaptation technology, the number N that order is data flow here _s, can obtain by following formula:

$\{\mathrm{\&Pi;},\mathrm{\&omega;},N_S\}=\arg \underset{\widehat{\mathrm{\&Pi;}},\widehat{\mathrm{\&omega;}},{\hat{N}}_S}{\max }f(\widehat{\mathrm{\&Pi;}},\widehat{\mathrm{\&omega;}},{\hat{N}}_S)---\left(4\right)$

But while utilizing formula (4), can find out one group of individual frequency sub-band of K ' in pre-coding matrix index, vectorial ω and the number N of data flow _sto meet formula (4).The same with formula (3), when in П, the quantity P of containing element gets different value, all can meet.While using formula (4), by receiving terminal, make rank adaptation decision-making.This is conducive to improve the probability that maximizes connection.While utilizing formula (3), by base station transceiver (BTS)/Node B (Node B), N is set _s.

Metric function f in above-mentioned formula (3) and formula (4) is the function of one or more pre-coding matrix indexes in frequency sub-band, corresponding length K ' and П in vectorial ω.This function can be realized with distinct methods.One of method is all used reference paper [8] (3GPP R1-031304 to each data flow exactly, " System-levelevaluation of OFDM-initial evaluation " Ericsson, Nov.17-21, 2003 (3GPPR1-031304, the system-level OFDM of < < estimates---> > according to a preliminary estimate), Ericsson, 17-21 day in November, 2003)) the effective power SIR mapping (EESM) in, suppose a certain set ω of frequency sub-band and for PMI vector or the single PMI of all frequency sub-band of ω, then with following formula table, show f:

$f(\mathrm{\&Pi;},\mathrm{\&omega;},N_S)=\min ({\mathrm{EESM}}_1(\mathrm{\&Pi;},\mathrm{\&omega;},N_S),...,{\mathrm{EESM}}_{N_S}(\mathrm{\&Pi;},\mathrm{\&omega;},N_S))---\left(5\right)$

N _sthe number of data flow, EESM (П, ω, N _s) be the EESM of data flow s, be wherein provided with N _sindividual data flow, and use with vectorial П in the corresponding pre-coding matrix of index and frequency sub-band ω.EESM is also channel matrix H. and the function of interference covariance matrix, omit to simplify expression herein.

Other method is that EESM is mapped in mutual (mutual) information of each data flow, suppose a certain set ω of frequency sub-band and for PMI vector or the single PMI of all frequency sub-band of ω, then total throughout or the transinformation content of cumulative each each frequency sub-band of data flow, the scalar output valve that obtains metric function f is as follows:

$f(\mathrm{\&Pi;},\mathrm{\&omega;},N_S)=\underset{s=1}{\overset{N_S}{\mathrm{\&Sigma;}}}{\log }_2(1+{\mathrm{EESM}}_s(\mathrm{\&Pi;},\mathrm{\&omega;},N_S))---\left(6\right)$

Another kind method is that f is regarded as given BLER (block error rate) (BLER) in the situation that, the reflection to total throughout:

$f(\mathrm{\&Pi;},\mathrm{\&omega;},N_S)=\underset{s=1}{\overset{N_S}{\mathrm{\&Sigma;}}}{g}_{\mathrm{BLER}}\left({\mathrm{EESM}}_s(\mathrm{\&Pi;},\mathrm{\&omega;},N_S)\right)---\left(7\right)$

Here g _bLER(x) function is for being mapped to corresponding maximum code block length (quantity of information bit) by the value of EESM, and under maximum code block length, the value of BLER is less than the ideal value of regulation.Therefore, formula (7) has provided the code block length sum of each data flow, and this code block length sum and expection throughput are directly proportional.

The method proposing in formula (5), (6) and (7) all supposes there are a plurality of code words, wherein block of information of encoding separately of each data stream transmitting.Another kind method is to use the code word of (larger), and this code word is inserted and is mapped in all data flow, and at this moment whole code word generates an EESM value:

$f(\mathrm{\&Pi;},\mathrm{\&omega;},N_S)={\mathrm{EESM}}_{1,...,N_S}(\mathrm{\&Pi;},\mathrm{\&omega;},N_S)---\left(8\right)$

It will be understood by those skilled in the art that and can carry out computation measure function f by several different methods.Transmission quality has multiple different definition, therefore also has multiple distinct methods to be used for estimating transmission quality.What formula (5) and (8) obtained is SNR value, and what formula (6) obtained is capability value, and what formula (7) obtained is goodput.These are all the different metrics of transmission quality, but in communication field, transmission quality also has much other metrics.Therefore above-mentioned formula (5) to formula (8) can be regarded four kinds in multiple channel quality estimation method as, but formula (5) to formula (8) can not be for limiting the scope of the invention.

In one embodiment of the invention, except one or more pre-coding matrix indexes of subset ω, receiver can also feed back for the supplementary set ω of frequency sub-band a pre-coding matrix index, here ω ∪ ω=Ω.If scheduler program determines to use the frequency sub-band in subset ω to send information, can use the pre-coding matrix index of frequency sub-band supplementary set.

Alternatively, in ω, the pre-coding matrix of frequency sub-band can be fixed.Therefore the indication of the pre-coding matrix of these frequency sub-band does not need signaling.Specifically, in this case, fixing pre-coding matrix can be unit matrix, or if the row and column of this fixing pre-coding matrix is not etc., it can be the row in unit matrix.

In the above-described embodiments, can also for example use average coding service cycle (RLC) by the pre-coding matrix index information in any compression method compressed subset ω, or the existing compression method in other this area.

Frequency sub-band in ω can be further divided into a plurality of son-frequency sub-band, and every height-frequency sub-band all has unique pre-coding matrix index.This method need to indicate the method that ω is son-frequency sub-band of dividing with label.

In one embodiment of the invention, transmitting terminal is BTS/Node B, and receiving terminal is travelling carriage/subscriber equipment (UE).In this embodiment, travelling carriage/UE is by precoding vector П, subset ω and the possible number N of data flow _ssend to BTS/Node B.BTS/Node B by these information of receiving as a reference, but does not need to strictly observe these information.In this embodiment, the value of K ' can be set by BTS/Node B, also the value of K ' can be set by travelling carriage/UE.

In another embodiment, transmitting terminal is travelling carriage/UE, and receiver end is BTS/Node B, and wherein BTS/Node B will comprise the number N that precoding vector П, subset ω and data flow are possible _sscheduling grant send to travelling carriage/UE.At this moment travelling carriage/user that it must strictly observes the information of receiving.

In another embodiment, set the number of elements P in П in system standard, P value can be determined according to data type, as according to system bandwidth, communication statistic etc.

Method of the present invention can be applied in a kind of receiving element and/or a kind of transmitter unit, in the travelling carriage/UE of operating software or BTS/Node B.Preferably, can use digital signal processor (DSP) or other equal processor to carry out each step in this method.

In table 1, the feedback quantity while having compared the group technology of using one group of every L OFDM frequency sub-band in the feedback quantity of the present invention's needs, the feedback quantity while feeding back completely and prior art.The rear two behaviors feedback quantity required for the present invention of table 1.

Table 1: the signaling consumption contrast table that feeding back precoding matrix index is required.(N is the required bit quantity of indication code table element)

Systematic function when relatively using unity feedback and the systematic function while using Frequency Band Selection and single precoding matrix index feedback (Fig. 2 institute example [b]), also carried out computer simulation experiment.

Simulation result is as shown in table 2.While utilizing single precoding matrix index feedback, though throughput has declined several percentage points slightly, it is about 1/3rd that feedback quantity has reduced, and this shows that precoding square index compression method of the present invention is very effective.

Table 2: l-G simulation test.

Table 2 is depicted as the comparison of unity feedback and throughput of the present invention and feedback load.Simulated environment is an ofdm system that bandwidth is 5MHz bandwidth, and this system signal is TU (typical metropolitan area) channel, and only comprises an alone family, and code table comprises 8 elements.

Those skilled in the art can further revise the method for reducing precoding feedback amount of information provided by the present invention, receiving element and transmitter unit on the basis of above-described embodiment.

Obviously, those skilled in the art can on the basis of above-described embodiment, make other application, modification, change and/or augment.Be appreciated that application, modification within the scope of every the claims in the present invention, change and/or augment and all belong to the present invention and protect content.

Reference paper

[1]3GPP R1-061246“Unified uplink CQI signaling by efficient labeling”，Huawei，Shanghai，May 2006.

[2]PCT/CN/2006/0004，“Method for sub-band indicator signaling”，Huawei，Patent application，March 2006.

[3]J.Choi，R.W.Heath Jr.，“Interpolation Based Unitary Precoding forSpatial Multiplexing MIMO-OFDM with Limited Feedback”，IEEEGlobecom Conference 2004，Dallas，USA，November 2004，page 214-218.

[4]J.Choi，R.W.Heath Jr.，“Interpolation Based Transmit Beamforming forMIMO-OFDM with Limited Feedback”，IEEE Transactions on SignalProcessing，Vol.53，No.11，November 2005，page 4125-4135.

[5]B.Mondahl，R.W.Heath Jr.，“Algorithms for Quantized Precoding inMIMO OFDM Beamforming Systems”，Proceedings of the SPIE，Volume5847，pp.80-87(2005).

[6]3GPP R1-061441，“Feedback Reduction for Rank-1pre-coding forE-UTRA downlink”，Texas Instruments，Shanghai，May 2006.

[7]3GPP R1-061439，“Evaluation of Codebook-based Precoding for LTEMIMO Systems”，Texas Instruments，Shanghai，May 2006.

[8]3GPP R1-031303，“System-level evaluation of OFDM-initialevaluation”Ericsson，Nov.17-21，2003.

Claims (8)

1. in a method for multicarrier multiple-input, multiple-output MIMO feeding back information in communication system, a plurality of subcarriers in described system form a set omega (n who contains K available frequency sub-band ₁..., n _k), it is characterized in that, described method comprises:

Each frequency sub-band in the combination of sets that traversal is comprised of described K available frequency sub-band and a fixing pre-coding matrix set and the combination of pre-coding matrix, select the individual frequency sub-band of K ' of limited quantity and P pre-coding matrix of the limited quantity corresponding with the individual frequency sub-band of K ' of described limited quantity simultaneously, the transmission quality of other frequency sub-band in the combination of sets being formed by described K available frequency sub-band and described fixing pre-coding matrix set described in the transmission quality of the combination of the individual frequency sub-band of described K ' and a described P pre-coding matrix is better than and the combination of pre-coding matrix, the individual frequency sub-band of wherein said K ' is contained in the subset ω (m of described set omega ₁..., m _k') in, the value of K ' meets K ' <K, and the value of P meets P=1,

To send to a transmitting terminal with the pre-coding matrix index of the described pre-coding matrix of identification for identifying the information of described subset ω.

2. method according to claim 1, wherein said transmitting terminal is base station transceiver or Node B, the receiving terminal corresponding with described transmitting terminal is travelling carriage or subscriber equipment.

3. method according to claim 2, the number K ' of the corresponding frequency sub-band of wherein said pre-coding matrix index is arranged by described base station transceiver or described Node B.

4. in a method for multicarrier multiple-input, multiple-output MIMO feeding back information in communication system, a plurality of subcarriers in described system form a set omega (n who contains K available frequency sub-band ₁..., n _k), it is characterized in that, described method comprises:

According to a transmission quality function, select the individual frequency sub-band of K ' of limited quantity and P pre-coding matrix of the limited quantity corresponding with the individual frequency sub-band of K ' of described limited quantity simultaneously, the individual frequency sub-band of wherein said K ' is contained in the subset ω (m of described set omega ₁..., m _k') in, the value of K ' meets K ' <K, and the value of P meets P=1;

To send to a transmitting terminal with the pre-coding matrix index of the described pre-coding matrix of identification for identifying the information of described subset ω.

5. method according to claim 4 wherein selects a described P pre-coding matrix and the individual frequency sub-band of described K ' that described transmission quality function is maximized simultaneously.

6. at a receiving element for multicarrier multiple-input, multiple-output MIMO feeding back information in communication system, a plurality of subcarriers in described system form a set omega (n who contains K available frequency sub-band ₁..., n _k), it is characterized in that, described receiving element comprises:

One device, for traveling through each frequency sub-band of the combination of sets being formed by described K available frequency sub-band and a fixing pre-coding matrix set and the combination of pre-coding matrix, select the individual frequency sub-band of K ' of limited quantity and P pre-coding matrix of the limited quantity corresponding with the individual frequency sub-band of K ' of described limited quantity simultaneously, the transmission quality of other frequency sub-band in the combination of sets being formed by described K available frequency sub-band and described fixing pre-coding matrix set described in the transmission quality of the combination of the individual frequency sub-band of described K ' and a described P pre-coding matrix is better than and the combination of pre-coding matrix, the individual frequency sub-band of wherein said K ' is contained in the subset ω (m of described set omega ₁..., m _k') in, the value of K ' meets K ' <K, and the value of P meets P=1,

One device, for sending to a transmitter unit with the pre-coding matrix index of the described pre-coding matrix of identification for identifying the information of described subset ω.

7. receiving element according to claim 6, wherein said receiving element is travelling carriage or subscriber equipment.

8. for the device at multicarrier multiple-input, multiple-output MIMO feeding back information in communication system, a plurality of subcarriers in described system form a set omega (n who contains K available frequency sub-band ₁..., n _k), it is characterized in that, described device comprises:

One parts, for traveling through each frequency sub-band of the combination of sets being formed by described K available frequency sub-band and a fixing pre-coding matrix set and the combination of pre-coding matrix, select the individual frequency sub-band of K ' of limited quantity and P pre-coding matrix of the limited quantity corresponding with the individual frequency sub-band of K ' of described limited quantity simultaneously, the transmission quality of other frequency sub-band in the combination of sets being formed by described K available frequency sub-band and described fixing pre-coding matrix set described in the transmission quality of the combination of the individual frequency sub-band of described K ' and a described P pre-coding matrix is better than and the combination of pre-coding matrix, the individual frequency sub-band of wherein said K ' is contained in the subset ω (m of described set omega ₁..., m _k') in, the value of K ' meets K ' <K, and the value of P meets P=1, with

One parts, for sending to a transmitting terminal with the pre-coding matrix index of the described pre-coding matrix of identification for identifying the information of described subset ω.