CN101247157A - Method and system for an alternating channel delta quantizer for 2x2 mimo pre-coders with finite rate channel state information feedback - Google Patents

Abstract

Aspects of a method and system for an alternating channel delta quantizer for 2x2 MIMO pre-coders with finite rate channel state information feedback may include quantizing a change in channel state information in a 2x2 MIMO pre-coding system onto a codebook using a cost function, and alternating the codebook between two codebooks, each of which comprises one or more unitary matrices. The channel state information may be a matrix V that may be generated using Singular Value Decomposition (SVD) or Geometric Mean Decomposition (GMD). The cost function f(A) may be defined by the following relationship: where A is a matrix of size N by N and a ij is element (i,j) of matrix A. The one or more unitary matrices may be generated from a first matrix and a second matrix. The first matrix and the second matrix may be generated using a Givens decomposition.

Description

The method and system that alternate channel quantizes in the MIMO precoder

Technical field

The present invention relates to the signal processing of communication system, more particularly, the present invention relates to the method and system that a kind of alternate channel δ that is used to have 2 * 2MIMO precoder of limited ratio channel condition information feedback quantizes.

Background technology

Mobile communication has changed the mode of people's communications, and mobile phone has been formed by original luxury goods and has been the necessity in people's daily life.The use of current mobile phone hinders by the social state domination rather than by geographical position or technology.Though voice connect the basic need of the communication of having satisfied, wherein mobile voice connects and continues even further be penetrated in every day in the life, and mobile internet will be next step of mobile communication revolution.Described mobile Internet becomes a public source of daily information naturally, and to the simple and general mobile access of this data, services mode that will be inevitable.

The third generation (3G) cellular network is to be used for realizing these demands of described mobile Internet and specially design.Because the growth of using and popularizing of these services, for for the Cellular Networks operator, will become more important as network capacity optimization cheaply and service quality factors such as (QoS) with respect at present.These factors can be improved methods such as launching technique and improvement receiver technology and realize by the careful network planning and operation.For this reason, carrier wave needs to make it increase the technology of descending throughput, like this, provides high QoS performance and speed with those services that provided by cable modem and/or DSL service provider that contend with.

In order to satisfy these demands, the communication system of all placing many antennas at transmitter and receiver has received increasing attention recently because of it can improve system greatly in the wireless fading channel environment capacity.These multi-antenna structures, the intelligent antenna technology of just knowing can be used for reducing multipath and/or signal and disturb when signal receives.Can predict intelligent antenna technology along with the base station facility spread out and cellular system in mobile phone user will be used widely the increase of the processing capacity requirement of described these systems.These require part is that described multimedia service will provide voice, video and data communication services because of caused from the transformation of serving to radio multimedium of future generation based on voice service.

The use of a plurality of emissions and/or reception antenna is designed to introduce diversity gain and improves the degree of freedom and receives the interference that produces in the processing with the opposing signal.Diversity gain is by increasing the performance that received signal to noise ratio and stable transmitting chain improve system.On the other hand, the more freedom degree allows the emission of a plurality of whiles, thereby the robustness (robustness) that antinoise signal is disturbed is provided, and/or has allowed higher channeling to reach higher capacity.For example, in having the communication system of a plurality of aerial receivers, M reception antenna collection can be used for eliminating fully (M-1) individual disturbing effect.Therefore, N signal can use N transmitting antenna to launch simultaneously in identical bandwidth, and individual the transmitting of described N then is divided into N signal alone by N the antenna collection that is configured in receiver.Use a plurality of systems that transmit and receive antenna can refer to multiple-input and multiple-output (MIMO) system.In specific mimo system, an attracting aspect of multiaerial system refers to by utilizing these emitting structurals can increase the capacity of system significantly.For fixing total transmitting power and bandwidth, the capacity that the MIMO structure can provide is along with the signal to noise ratio (snr) dynamic change that increases.For example, under the situation of the weak channel of multipath, for the every increase of SNR 3dB, the capacity that the MIMO structure can increase system arrives near M bit/cycle (cycle).

Because the increase of volume, the raising of complexity, and the expense that the increase of power consumption causes increases, thus the restriction multiaerial system is used in radio communication widely.The problem that this has become wireless system design and application need to note.As a result, may pay close attention to the link that can support single user's point-to-point about some researchs of multiaerial system, other research may be paid close attention to multi-user's scene.The communication system of using many antennas very great achievement degree is improved the capacity of system.

Using the MIMO technology is in order to obtain very large performance gain, however this need provide channel information to transmitter to allow the MIMO preliminary treatment.Benefit from or need be called channel condition information (CSI) based on the MIMO preliminary treatment of MIMO transmitter and other MIMO technology about the knowledge of channel.In addition, because many wireless systems are with the operation of Frequency Division Duplexing (FDD) (FDD) pattern,, uplink and downlink use different frequencies so connecting.In these cases, the channel by measuring receiver also feeds back described information, so just can carry out the channel measurement of transmitter.Yet owing to the increase of transmission and reception antenna quantity in the mimo system, feeding back channel state information comprises the very transmission of big data quantity.Therefore need limit feedback, make it can not influence performance as far as possible.In these cases, also need obtain between the ratio compromise in system self-adaption speed and feedback.

Compare by the many aspects of introducing in conjunction with the accompanying drawings with the application's further part of the present invention, the restriction and the drawback that exist in the existing and conventional method, it is very obvious to become to those skilled in the art.

Summary of the invention

The present invention relates to the method and system that a kind of alternate channel δ that is used to have 2 * 2MIMO precoder of limited ratio channel condition information feedback quantizes, showing fully in conjunction with at least one accompanying drawing and/or describing, and in claims, setting forth more completely.

According to an aspect of the present invention, a kind of method that is used for process communication signals comprises:

The trace utilization cost function is quantized to the variation on the channel condition information in 2 * 2MIMO pre-coding system first on first code book, and described first code book comprises one or more unitary matrice;

The trace utilization cost function is quantized to the variation on the channel condition information in 2 * 2MIMO pre-coding system second on second code book, and described second code book comprises one or more unitary matrice; And

Repeating described first in an alternating manner quantizes and described second quantification.

Preferably, described channel condition information is a matrix V.

Preferably, described method comprises that further use singular value decomposition (SVD) produces described matrix V.

Preferably, described method comprises that further using geometric mean to decompose (GMD) produces described matrix V.

Preferably, described cost function f (A) is defined by following relational expression:

$f\left(A\right)=\left(\frac{1}{N}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{\left|a_{\mathrm{jj}}\right|}^2\right)$

Wherein A is the matrix of N * N, a _IjBe matrix A element (i, j).

Preferably, described method further comprises from first matrix and second matrix and produces described one or more unitary matrice.

Preferably, described method comprises that further using Robin Givens (Givens) to decompose produces described first matrix and second matrix.

Preferably, described method further comprises the dynamic range of revising described first code book and/or second code book by modification step-length variable.

Preferably, the element index that described method further is included in the described MIMO pre-coding system described first code book or described second code book sends to transmitter from receiver, and wherein the described variation on the channel condition information is quantized on described first code book or second code book.

Preferably, described method further comprises and uses a described unitary matrice to change the matrix at the transmitter place of described MIMO pre-coding system linearly.

According to an aspect of the present invention, a kind of system that is used for process communication signals comprises:

2 * 2MIMO the pre-coding system that comprises one or more circuit, described one or more circuit are used for:

The trace utilization cost function is quantized to the variation on the channel condition information in 2 * 2MIMO pre-coding system first on first code book, and described first code book comprises one or more unitary matrice;

The trace utilization cost function is quantized to the variation on the channel condition information in 2 * 2MIMO pre-coding system second on second code book, and described second code book comprises one or more unitary matrice; And

Repeating described first in an alternating manner quantizes and described second quantification.

Preferably, described channel condition information is a matrix V.

Preferably, described one or more circuit uses singular value decomposition (SVD) to produce described matrix V.

Preferably, described one or more circuit uses geometric mean to decompose (GMD) and produces described matrix V.

Preferably, described cost function f (A) is defined by following relational expression:

$f\left(A\right)=\left(\frac{1}{N}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{\left|a_{\mathrm{jj}}\right|}^2\right)$

Wherein A is the matrix of N * N, a _IjBe matrix A element (i, j).

Preferably, described one or more circuit produces one or more unitary matrice from first matrix and second matrix.

Preferably, described one or more circuit uses Robin Givens to decompose and produces described first matrix and second matrix.

Preferably, described one or more circuit is revised the dynamic range of described first code book and/or second code book by revising the step-length variable.

Preferably, described one or more circuit sends to transmitter with the element index of described first code book or described second code book from receiver in described MIMO pre-coding system, wherein the described variation on the channel condition information is quantized on described first code book or second code book.

Preferably, described one or more circuit uses a described unitary matrice to change the matrix at the transmitter place of described MIMO pre-coding system linearly.

These and other advantage of the present invention, aspect and new features, with and specific embodiment, can from following description and figure, obtain understanding more completely.

Description of drawings

Figure 1A is the schematic diagram in conjunction with the honeycomb multipath communication of the embodiment of the invention between base station and mobile computing terminal;

Figure 1B is the schematic diagram according to the MIMO communication system of the embodiment of the invention;

Fig. 2 is the block diagram according to the MIMO precoding transceiver chain model of the embodiment of the invention;

Fig. 3 is the block diagram according to the MIMO pre-coding system of the limited ratio channel condition information feedback of having of the embodiment of the invention;

Fig. 4 is the flow chart that quantizes feedback algorithm according to the typical precoding δ of the embodiment of the invention;

Fig. 5 is the performance map according to the typical 2 * 2MIMO system with 4 element code book C of the embodiment of the invention.

Embodiment

Embodiments of the invention have been introduced the method and system that a kind of alternate channel δ that is used to have 2 * 2MIMO precoder of limited ratio channel condition information feedback quantizes.Being used for having the method and system that the alternate channel δ of 2 * 2MIMO precoder of limited ratio channel condition information feedback quantizes comprises: the trace utilization cost function is quantized to code book with the variation on the channel condition information of 2 * 2MIMO pre-coding system, and between two code books, hocket, wherein each code book comprises one or more unitary matrice.Described channel condition information is to use singular value decomposition (SVD) or geometric mean to decompose the matrix V that (GMD) produces.Described cost function f (A) is defined by following relational expression:

$f\left(A\right)=\left(\frac{1}{N}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{\left|a_{\mathrm{jj}}\right|}^2\right)$

Wherein A is the matrix of N * N, a _IjBe matrix A element (i, j).Described one or more unitary matrice produces from first matrix and second matrix.Described first matrix and second matrix can use Robin Givens to decompose and produce.The dynamic range of described two code books is made amendment by revising the step-length variable.The element index of described code book is sent to transmitter from receiver in the MIMO pre-coding system, wherein the described variation on the channel condition information is quantized on the described code book.Use a unitary matrice can change the matrix at the transmitter place of MIMO pre-coding system linearly.

Figure 1A shows in conjunction with the honeycomb multipath communication of the embodiment of the invention between base station and mobile computing terminal.With reference to Figure 1A, house 120, portable terminal 122, factory 124, base station 126, automobile 128 and communication path 130,132 and 134 have been provided.

Base station 126 and portable terminal 122 include suitable logic, circuit and/or code, are used for producing and handling the MIMO signal of communication.Radio communication between base station 126 and portable terminal 122 can be undertaken by wireless channel.Described wireless channel comprises a plurality of communication paths, for example, and communication path 130,132 and 134.Described wireless channel can move and dynamic change along with portable terminal 122 and/or automobile 128.In some cases, portable terminal 122 is line-of-sight propagation (LOS) with base station 126.In other cases, may not direct sighting distance between portable terminal 122 and the base station 126, radiofrequency signal is propagated between the reflection communication path between the communication entity, representative communication path 130,132 and 134 as shown in the figure.Described radiofrequency signal can be reflected by the obstacle such as the mountain of man-made structures such as house 120, factory 124 or automobile 128 or existence naturally.Such system refers to non line of sight (NLOS) communication system.

Communication system can comprise LOS and NLOS signal component simultaneously.If there is the LOS signal component, described LOS signal component is than strong many of NLOS signal component.In some communication systems, the NLOS signal component can produce to be disturbed and the reduction receiver performance.This refers to multipath and disturbs.For example, communication path 130,132 and 134 reaches portable terminal 122 and has different delays.Communication path 130,132 and 134 can also have different decay.For example, in down link, the signal that receives at portable terminal 122 can be a differential declines communication path 130,132, and/or the summation of 134 signal, and these different communication paths may be nonsynchronous and dynamic changes.Such channel is called weak multipath channel.Weak multipath channel can be introduced interference, but also can introduce the diversity and the degree of freedom for described wireless channel.In the base station and/or portable terminal have the communication system of many antennas, mimo system for example, be particularly suitable for utilizing the characteristic of wireless channel and can obtaining very big performance gain by weak multipath channel, with respect in the base station 126 and portable terminal 122 have the communication system (particularly NLOS communication system) of single antenna, the communication system of described many antennas can obtain very big performance and improve.

Figure 1B shows the schematic diagram according to the MIMO communication system of the embodiment of the invention.With reference to Figure 1B, show MIMO transmitter 102 and MIMO receiver 104, and antenna 106,108,110,112,114,116.Also show wireless channel among the figure, described channel comprises communication path h ₁₁, h ₁₂, h ₂₂, h ₂₁, h _2NTX, h _1NTX, h _{NRX 1}, h _{NRX 2}, h _{NRX NTX}, h wherein _MnCan represent channel coefficients from transmitter antenna n to receiver antenna m.Has N _TXIndividual transmitter antenna and N _RXIndividual receiver antenna.Give emission symbol x among the figure ₁, x ₂, x _NTXWith receiving symbol y1, y2, y _NRX

MIMO transmitter 102 includes suitable logic, and circuit and/or code are used for producing emission symbol x _iI ∈ 1,2 ... N _TX, described symbol is by 106,108,110 emissions of the transmitting antenna shown in Figure 1B.MIMO receiver 104 includes suitable logic, and circuit and/or code are used to handle the receiving symbol y that receives by the reception antenna shown in Figure 1B 112,114,116 _iI ∈ 1,2 ... N _RX.Shown in input/output relation between that launch in mimo system and the signal that receives can be expressed as:

y＝Hx+n

Y=[y wherein ₁, y ₂... y _NRX] ^TBe to have N _RXThe column vector of individual element. ^TExpression vector transposition, H=[h _Ij]: i ∈ 1,2 ... N _RX; J ∈ 1,2 ... N _TXExpression N _RX* N _TXThe channel matrix of dimension, x=[x ₁, x ₂... x _NTX] ^TBe to have N _TXThe column vector of individual element, n are to have N _RXThe noise samples column vector of individual element.Channel matrix H can be write as H=U ∑ V under the situation of using singular value decomposition (SVD) ^H, wherein. ^HExpression Hamilton's transposition (hermitian transpose), U is N _RX* N _TXUnitary matrice, ∑ is N _TX* N _TXDiagonal matrix, and V is N _TX* N _TXUnitary matrice.Also can use other matrix decomposition rather than SVD to decompose with diagonalization or the described matrix H of conversion.If the receiver algorithms of carrying out in the MIMO receiver 104 are the Interference Cancellations (OSIC) that for example sort, then other can transition matrix H to time/matrix decomposition of upper triangular matrix also is fine.Such decomposition comprises that geometric mean decomposes (GMD), wherein H=QRP ^H, wherein R can be that the geometric mean of the singular value of H is positioned at the upper triangular matrix on the diagonal element, Q and P can be unitary matrice.

Fig. 2 shows the block diagram according to the MIMO precoding transceiver chain model of the embodiment of the invention.With reference to figure 2, the MIMO pre-coding system 200 that shows comprises MIMO transmitter 202, MIMO equivalence baseband channel 203, MIMO receiver 204 and addition module 208.MIMO transmitter 202 comprises transmitter (TX) baseband processing module 210 and emission precoding module 214.MIMO equivalence baseband channel 203 comprises wireless channel 206, TX radio frequency (RF) processing module 212 and receiver (RX) RF processing module 218.MIMO receiver 204 comprises precoding decoder module 216 and RX baseband processing module 220.Also show symbolic vector s, precoding vectors x, noise vector n among the figure, receive vector y and channel-decoding vector y '.

MIMO transmitter 202 comprises baseband processing module 210, and it includes suitable logic, circuit and/or code, is used to produce the MIMO base band transmit.Described MIMO base band transmit can be transferred to emission precoding module 214.Through suitably encoding with emission in wireless channel 206, emission precoding module 214 includes suitable logic, circuit and/or code to be used to making it carry out these functions to baseband signal in emission precoding module 214.TX RF processing module 212 includes suitable logic, and circuit and/or code are used for making the signal that is transferred to TX RF processing module 212 to be modulated onto radio frequency (RF) to launch at wireless channel 206.RX RF processing module 218 includes suitable logic, and circuit and/or code are used for carrying out the radio-frequency front-end function to be received in the signal of wireless channel 206 emissions.RX RF processing module 218 includes suitable logic, and circuit and/or code are used for its input signal is demodulated to baseband signal.Addition module 208 is illustrated in the MIMO receiver noise is added in the signal that receives.MIMO receiver 204 comprises precoding decoder module 216, and the signal that its linear codec receives also transmits described signal to RX baseband processing module 220.RX baseband processing module 220 includes suitable logic, and circuit and/or code are used for this baseband signal is used further signal processing.

MIMO transmitter 202 comprises baseband processing module 210, and it includes suitable logic, and circuit and/or code are used to produce the MIMO base band transmit.Described MIMO base band transmit, just symbolic vector s is transferred to emission precoding module 214.Symbolic vector s can be N _TXThe vector of * 1 dimension.

The 214 couples of symbolic vector s of emission precoding module carry out linear transformation, make x=Ws, and wherein the dimension of W is N _TXMultiply by the length of s, and x=[x ₁, x ₂... x _NTX] ^TEach element of precoding vectors x is at available N _TXLaunch on the individual different antenna.

The precoding vectors x of emission is by MIMO equivalence baseband channel 203.By N _RXThe signal y that individual receiver antenna receives transmits x by MIMO equivalence baseband channel 203 conversion (being represented by matrix H), and adds that noise component(s) (being expressed as noise vector n) obtains.Shown in addition module 208, receive vector y and be expressed as y=Hx+n=HWs+n.Receive vector y and be transferred to precoding decoder module 216, wherein can carry out linear codec operation B to obtain decoded vector y '=B receiving vector y ^HY=B ^HHWs+B ^HN, wherein B is the complex matrix of suitable dimension.Decoded vector y ' then is transferred to RX baseband processing module 220, carries out further signal processing in this output to precoding decoder module 216.

If it is all known at MIMO transmitter 202 and MIMO receiver 204 ends to be applied to launch the MIMO equivalence baseband channel 203 transfer function H of precoding vectors x, then described channel can for example, be provided with W=V and B=U, wherein H=U ∑ V by diagonalization ^HIt is singular value decomposition.In these cases, channel-decoding vector y ' is shown in the following relational expression:

y’＝U ^HU∑V ^HVs+U ^Hn＝∑s+U ^Hn

Because ∑ is a diagonal matrix, do not disturb between the element of the symbolic vector s among the y ' to exist, therefore described wireless communication system is similar to and has up to N _TXThe wireless communication system of individual parallel single antenna is such, and for each element of s, the order of channel matrix H can be smaller or equal to N _TX

Fig. 3 shows the block diagram according to the MIMO pre-coding system of the limited ratio channel condition information feedback of having of the embodiment of the invention.With reference to figure 3, the MIMO pre-coding system 300 that illustrates comprises part MIMO transmitter 302, part MIMO receiver 304, wireless channel 306, addition module 308 and feedback channel 320.Part MIMO transmitter 302 comprises emission precoding module 314.Part MIMO receiver 304 comprises precoding decoder module 316, channel estimation module 322, channel quantitative module 310, channel decomposing module 312 and code book processing module 318.Fig. 3 also shows symbolic vector s, precoding vectors x, noise vector n, receives vector y and decoded vector y '.

Emission precoding module 314, wireless channel 306, addition module 308 and precoding decoder module 316 are basic identical with the emission precoding module 214 shown in Fig. 2, MIMO equivalence baseband channel 203, addition module 208 and precoding decoder module 216.Channel estimation module 322 includes suitable logic, and circuit and/or code are used to estimate the transfer function of wireless channel 206.Channel estimation value can send channel decomposing module 312 to, and channel decomposing module 312 includes suitable logic, and circuit and/or code are used to decompose channel.In this respect, the channel communication that is decomposed is connected to channel quantitative module 310.Channel quantitative module 310 includes suitable logic, and circuit and/or code are used for described channel strip is quantized to code book.Code book processing module 318 includes suitable logic, and circuit and/or code are used to produce code book.Feedback channel 320 is expressed as the channel from part MIMO receiver 304 transmitting channel state informations to part MIMO transmitter 302.

In a lot of wireless systems, channel condition information about the understanding of Channel Transmission matrix H, may be ignorant for transmitter and receiver just.Yet,, may wish to know partial channel knowledge at least at transmitter terminal in order to utilize pre-coding system as shown in Figure 2.In the disclosed embodiments of the invention as Fig. 2, MIMO transmitter 302 needs and is used for the unitary matrice V that carries out precoding in the emission precoding module 214 of MIMO transmitter 202.

In frequency division multiplexing (FDD) system, the communication band that is used for the downlink communication from the base station to the portable terminal is different with the frequency band that is used for uplink communication.Because the difference of frequency band, the channel measurement of up link is otiose for down link generally, and vice versa.In these cases, only carry out described measurement, and channel condition information (CSI) can transmit back transmitter by the mode of feedback at receiver end.Reason hereto, CSI can feed back to the emission precoding module 314 of part MIMO transmitter 302 by feedback channel 320 from part MIMO receiver 304.Emission precoding module 314, wireless channel 306 and addition module 308 are basic identical with corresponding module 214,203 and 208 shown in Figure 2.

At part MIMO receiver 304 places, the signal y of reception can be used for estimating channel transfer function H in channel estimation module 222, uses

Expression.For example, described estimated value can further resolve into diagonal matrix or triangular matrix form, and this depends on specific receiver realization, explains as Fig. 2.For example, channel decomposing module 312 can be carried out the SVD decomposition: $\hat{H}=\hat{U}\widehat{\mathrm{\Σ}}{\hat{V}}^H.$ Matrix H and It is the matrix of order r=2.This can be following situation, for example, when the quantity of the quantity of transmitting antenna and reception antenna is 2, i.e. N _TX=N _RX=2.Need be with matrix

Being quantized into dimension is N _TX* N _TXMatrix V _k, wherein $V_k=V_{k-1}\&CenterDot;{\mathrm{<figure-callout\; id="0"\; label="Q\; q"\; filenames="S2008100097209E00061.png"\; state="\{\{state\}\}">Q</figure-callout>}}_q^{}$ From last V _kGenerate, i.e. V _K-1, the tenth of the twelve Earthly Branches spin matrix Q _q ⁰From predefined limited unitary matrice collection C _d={ Q _iThe middle generation.Described unitary matrice collection C _dJust be called code book.Matrix Change can be slowly with respect to the channel renewal rate.In these situations, send and upgrade to last quantization matrix V _K-1(rather than send to new matrix V _k) and use the channel storage, like this can be more economically.By from generating V _kCode book C _dThe middle matrix Q that seeks _q ⁰, in some sense, V _kApproach most matrix

This is enough to matrix Q _q ⁰Index q send to the emission precoding module 314.Said process can be finished by the feedback channel 320 from channel quantitative module 310.Part MIMO transmitter 302 need be known code book C _dCode book C _dSlower than channel transfer function H variation, thus be enough in emission precoding module 314, be updated periodically code book C from code book processing module 318 by feedback channel 320 _dCode book C _dCan be static or adaptive.In addition, code book C _dCan also concentrate self adaptation or non-self-adapting ground to select from a code book, these code books comprise the code book of self adaptation and/or Static Design.In these cases, part MIMO receiver 304 can be put at any time and inform that employed code book is to part MIMO transmitter 302.

Under the situation that channel matrix H can slowly change with respect to the channel condition information feedback velocity, it is feasible further reducing feedback velocity with the cost that reduces the instantaneous degree of freedom.This can finish by being divided into two code books than big code book C, i.e. C={Q _i}={ C _Even∪ C _Odd}={ C _Even={ Q _i∪ C _Odd={ Q _i.Code book C _EvenAnd C _OddHalf element that respectively comprises C.In some cases, code book C _EvenAnd C _OddBe nonoverlapping, i.e. { C _Even={ Q _i∩ C _Odd={ Q _i}= }, wherein  represents empty set.Matrix Be quantized into V at every turn _kThe time, code book C _EvenOr C _OddHave only one to be used to quantize purpose among both, because quantization code book C _d∈ { C _Even, C _Odd.Code book C _dAt different quantification situations, at code book C _EvenAnd C _OddBetween replace in wheel (round-robin) mode of changeing.For example, if

Be quantized into V _kOccur in time point kT, wherein k is that integer and T are the time intervals between the quantification situation continuously, uses code book C so when k is even number _Even, when k is odd number, use code book C _OddThis need the index k of part MIMO receiver 304 keep with part MIMO transmitter 302 manipulative indexings synchronously.By in the above described manner code book being divided quantization code book C _dOnly comprise half element of code book C in any point of quantification, promptly the radix of C is | C|=2 ^M=2|C _d|=22 ^M-1And this is enough to feed back and makes the indexed M bit of element among the C.Radix by the code book selecting to be used to quantize is | C _d|=| C|/2=|C _Even|=| C _Odd|, be enough to feed back the M-1 bit, shown in above equation.Since code book C={Q _iElement be rotation, use the code book C reduce size _dCan be interpreted as limiting the described subclass that rotates to be coordinate in each point of quantification.Yet, though described code book can be at C _EvenAnd C _OddBetween alternately, the rotation around any axle (or coordinate) in C is possible, but at C _EvenAnd C _OddIn can comprise the continuous rotation of some.Therefore, it is feasible reducing feedback velocity, because can use the code book C that reduces size _dBe used for quantizing.In some cases, by limiting quantization code book C _dSize and the direction of effectively rotation reduce feedback velocity, may need a plurality of rotations to obtain identical result by using complete code book C to finish with rotation still less.Therefore, use code book alternately to may be interpreted as and obtain compromise between the speed of rotation arbitrarily feedback data speed.Yet, in many cases, matrix Can slowly rotate, and to sacrifice rotary speed and reduce feedback velocity be favourable that it is feasible reducing the control information expense on the up link thus and increasing the data available payload.

Matrix

Can be quantized into V by relation as described below _k:

${\mathrm{<figure-callout\; id="0"\; label="Q\; q"\; filenames="S2008100097209E00061.png"\; state="\{\{state\}\}">Q</figure-callout>}}_q^{}=\arg {\max }_{{\hat{Q}}_q\&Element;C_d}f\left({\hat{V}}^H{V}_k\right)={\arg \max }_{{\hat{Q}}_q\&Element;C_d}f\left({\hat{V}}^H{V}_{k-1}{\hat{Q}}_q\right)$

$f\left(A\right)=\left(\frac{1}{N}\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}{\left|a_{\mathrm{jj}}\right|}^2\right)$

A=[a wherein _Ij] and the dimension of A be N * N.Therefore, can selection matrix Q _q ⁰Be C in the code book _dIn matrix It can maximize function as defined above

Function f (.) can be to the absolute value of the diagonal element of its input matrix square ask average.By maximization f (.), in some sense, matrix V _kSelection satisfy product

At utmost similar in appearance to unit matrix.The expression formula of above f (.) can maximize the momentary output of described precoding MIMO system under some approximation method.Therefore, channel H can estimate in channel estimation module 322, and decomposes in channel decomposing module 312.

In channel quantitative module 310, matrix, for example Can be quantized into matrix V _k=V _K-1Q _q ⁰, index q feeds back to part MIMO transmitter 302 by feedback channel 320.From the code book C of code book processing module 318, can send to part MIMO transmitter 302 by feedback channel 320, but its feedback frequency is slower than index q.Described code book C can also not be chosen as and change in time.And described code book C can also concentrate self adaptation or non-self-adapting ground to select from code book, and these code books comprise the code book of self adaptation and/or Static Design.As code book C _dRadix | C _d| satisfy | C _d|≤2 ^MThe time, in order to feed back index q, the M bit is just enough.

Emission precoding module 314 can be carried out for example linear transformation x=V _kS.The precoding decoder module 316 of receiver end can be carried out linear transformation $y^{\&prime;}={\hat{U}}^{H}y.$

Code book C can comprise multiple unitary matrice { Q _q.Desirable code book is the code book that comprises easy adjustment dynamic range.At spin matrix { Q _q, this absolute range that can be interpreted as collecting the rotatable angle of C can be adjusted maybe and can set, and granularity (granularity) also is that so described granularity is adjacency matrix Q _qBetween step-length.The adaptivity of dynamic range makes the different channels condition of code book applicable to wide region.Especially, code book C can be adapted to the speed of the variation of wireless channel matrix H.

A structure code book C _dTypical protocol can use matrix { Q _qThe single entry characteristic.2 * 2 multiple unitary matrice Q that are used for typical 2x2MIMO pretreatment system _qDecompose (Givens decomposition) and be expressed as relation according to Robin Givens by two angle parameterizations:

The angular range that wherein above-mentioned angle changes is: φ ∈ [pi/2, pi/2] and  ∈ [π, π].Specifying Q _qBe under the situation of unit matrix, rotation does not take place.Therefore, in some sense, matrix { Q _qThe approximate unit matrix.Code book C constructs with following relation:

C＝{Q _q(φ，)|φ＝±δ·π/2，＝±δ·π} (2)

δ≤1st wherein, step-length.Just, can be from matrix stack { Q _qIn construct code book C, matrix stack { Q _qCan from the angle of some, generate according to equation (1).In an embodiment of described code book, the collection C of structure comprise from angle collection φ=± the δ pi/2, =± matrix { Q that constructs in may the making up of δ π _q, such as equation (2) and equation (1) definition.With { Q _qIn possible combination of angles in conjunction with last probable value of inferring out by angle, will obtain radix | the code book of C|=4, promptly | C| is different from and is included in the matrix Q of collection among the C _qCollection C _EvenAnd C _OddEach all comprises 2 element Q _qIn one embodiment of the invention, described code book can be selected but be not limited to the code book that following relation provides:

$C_{\mathrm{even}=}\{\left[\begin{array}{cc}{e}^{\mathrm{j\&delta;}\&CenterDot;\mathrm{\&pi;}/2}& 0\\ 0& 1\end{array}\right]\&CenterDot;\begin{array}{c}\left[\begin{array}{cc}\cos \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}& \sin \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}\\ -\sin \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}& \cos \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}\end{array}\right],\left[\begin{array}{cc}{e}^{-\mathrm{j\&delta;}\&CenterDot;\mathrm{\&pi;}/2}& 0\\ 0& 1\end{array}\right]\&CenterDot;\left[\begin{array}{cc}\cos \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}& \sin \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}\\ -\sin \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}& \cos \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}\end{array}\right]\}---\left(3\right)\end{array}$

$C_{\mathrm{odd}=}\{\left[\begin{array}{cc}{e}^{\mathrm{j\&delta;}\&CenterDot;\mathrm{\&pi;}/2}& 0\\ 0& 1\end{array}\right]\&CenterDot;\left[\begin{array}{cc}\cos \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}& -\sin \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}\\ \sin \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}& \cos \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}\end{array}\right],\begin{array}{c}\left[\begin{array}{cc}{e}^{-\mathrm{j\&delta;}\&CenterDot;\mathrm{\&pi;}/2}& 0\\ 0& 1\end{array}\right]\&CenterDot;\left[\begin{array}{cc}\cos \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}& -\sin \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}\\ \sin \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}& \cos \mathrm{\&delta;}\&CenterDot;\mathrm{\&pi;}\end{array}\right]\}---\left(4\right)\end{array}$

Step-length δ≤1 allows to adjust matrix { Q _qDynamic range, therefore above-mentioned code book structure C={C _Even∪ C _OddCrock up channel matrix H when being suitable for the wide region of different rate of changes.In these situations, with B _Cd=1 bit feeds back to part MIMO transmitter 302 from part MIMO receiver 304, with this from code book C={C _Even∪ C _OddFeedback matrix Q _q ⁰The index q that selects.As explained above, with respect to quantization code book C _dNeeded feedback velocity B when equaling C _C=2, this method will reduce by 1 feedback bits.For typical 2 * 2MIMO system, so feedback velocity can be that 1 bits/channel is upgraded.

Fig. 4 is the flow chart that quantizes feedback algorithm according to the typical precoding δ of the embodiment of the invention.With reference to figure 4, show beginning step 402, determining step 406 and treatment step 408,410,412,414,416,418,420.

In step 404,, counting variable k begins a kind of typical precoding δ quantification feedback algorithm by being set.Variable k is used for reflecting respectively the strange code book C of even summation _EvenAnd C _OddUse.Variable k is in MIMO receiver and the place's initialization of MIMO transmitter, and variable k need promptly keep synchronously at MIMO receiver and MIMO transmitter place two entity places maintenances synchronously.In step 406, if k is an even number, quantization code book is set at C _d=C _EvenIf k is an odd number, quantization code book is set at C _d=C _OddDescribed quantification can be set at MIMO transmitter and MIMO receiver place.In step 412,, in channel estimation module 322, obtain channel estimation value at MIMO transmitter place.Can provide channel matrix like this

The channel estimation value of form.In step 414, in order to obtain matrix

Channel matrix decomposition

For example, channel decomposing module 312 can use singular value decomposition (SVD) or geometric mean to decompose (GMD) to obtain matrix

In step 416, based on current quantization code book C _d, matrix

Be quantized into matrix V _k, it is spin matrix Q _q ⁰∈ C _dFunction.This can finish in channel quantitative module 310.In step 418, corresponding to C _q ⁰∈ C _dIndex q be sent to the MIMO transmitter from the MIMO receiver, for example,, send to from channel quantitative module 310 and to send precoding module 314, as shown in Figure 3 by feedback channel 320.In step 420, all increase progressively counting variable k at MIMO transmitter and MIMO receiver place, described then feedback algorithm loops back step 406.

Fig. 5 is the performance map according to the typical 2x2MIMO system that tool 4 element code book C are arranged of the embodiment of the invention.With reference to figure 5, show spectrum efficiency (bps/Hz) axle and the signal to noise ratio (snr) axle.Also show desirable wave beam forming curve 502 and 2 bit code book curves 504 among the figure.

Because code book C has 4 elements, code book C _d={ C _Even, C _OddComprise 2 elements, therefore need feedback B=log ₂(2)=1 bit.Step-length is chosen as δ≤1.Although only feed back 1 bit, the performance of 2 bit code book curves 504 is similar to desirable wave beam forming curve 502.As can be seen from Figure 5, the performance of 2 bit code books 504 is near the performance of desirable wave beam forming 502.Under the situation of desirable wave beam forming 502, emission precoding module 214 places of transmitter 202 know channel condition information, i.e. wireless channel H intactly, exactly.Therefore, the performance loss of using above-mentioned 2 bit code books 504 to cause is relatively little with respect to the ideal communication channel state information.

According to embodiments of the invention, the method and system that a kind of alternation channel δ that is used for having 2 * 2MIMO precoder of finite rate channel condition information feedback quantizes comprises: channel quantitative module 310 trace utilization cost functions with 2 * 2MIMO pre-coding system 300 in variation on the channel condition information quantize to code book, and on two code book in the alternate channel processing module 318 between the code book, wherein each code book comprises one or more unitary matrice.Described channel condition information is to use singular value decomposition (SVD) or geometric mean to decompose the matrix V that (GMD) produces in code book processing module 318.Described cost function f (A) is defined by following relational expression:

$f\left(A\right)=\left(\frac{1}{N}\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}{\left|a_{\mathrm{jj}}\right|}^2\right)$

Wherein A is the matrix of N * N, a _IjBe matrix A element (i, j).First matrix and second matrix of described one or more unitary matrice from code book processing module 318 produces.First matrix and second matrix can use Robin Givens to decompose and produce.The dynamic range of described two code books is made amendment by revising the step-length variable.The element index of described code book is sent to transmitter 302 from receiver 304 in MIMO pre-coding system 300, wherein the described variation on the channel condition information is quantized on the described code book.In emission precoding module 314, can use a unitary matrice to change the matrix at the transmitter place of MIMO pre-coding system linearly.

Another one embodiment of the present invention provides a machine readable memory, computer program of storage has the code segment that at least one can be carried out by machine on it, thereby impels this machine to carry out each step of the method that a kind of alternation channel δ that is used to have 2 * 2MIMO precoder of finite rate channel condition information feedback described herein quantizes.

Therefore, the present invention can pass through hardware, software, and perhaps soft, combination of hardware realizes.The present invention can realize with centralized system at least one computer system, perhaps be realized with dispersing mode by the different piece in the computer system that is distributed in several interconnection.Anyly can realize that the computer system of described method or miscellaneous equipment all are applicatory.The combination of software and hardware commonly used can be the general-purpose computing system that computer program is installed, and by installing and carry out described program-con-trolled computer system, it is moved by described method.In computer system, utilize processor and memory cell to realize described method.

The present invention can also implement by computer program, and described program comprises whole features that can realize the inventive method, when it is installed in the computer system, by operation, can realize method of the present invention.Computer program in the presents refers to: one group of any expression formula of instructing that can adopt any program language, code or symbol to write, this instruction group makes system have information processing capability, with direct realization specific function, or after carrying out following one or two step, realize specific function: a) convert other Languages, coding or symbol to; B) reproduce with different forms.

The present invention describes by several specific embodiments, it will be appreciated by those skilled in the art that, without departing from the present invention, can also carry out various conversion and be equal to alternative the present invention.In addition, at particular condition or concrete condition, can make various modifications to the present invention, and not depart from the scope of the present invention.Therefore, the present invention is not limited to disclosed specific embodiment, and should comprise the whole execution modes that fall in the claim scope of the present invention.

Explanation

The application quote and require that application number is 60/889374, the applying date is the priority of the U.S. Provisional Patent Application on February 12nd, 2007, and it introduced among the application in full.

Also reference of the application:

Application number is 60/889382 U.S. Patent application, and the applying date is on February 12nd, 2007;

Application number is 60/889397 U.S. Patent application, and the applying date is on February 12nd, 2007;

Application number is 60/889406 U.S. Patent application, and the applying date is on February 12nd, 2007;

Application number for _ _ _ _ U.S. Patent application (acting on behalf of case 18340US02), the applying date is on August 30th, 2007;

Application number for _ _ _ _ U.S. Patent application (acting on behalf of case 18341US02), the applying date is on August 30th, 2007;

Application number for _ _ _ _ U.S. Patent application (acting on behalf of case 18342US02), the applying date is on August 30th, 2007;

The above each part application that provides at this as a whole and with reference to quoting.

Claims (10)

1, a kind of method that is used for process communication signals is characterized in that, described method comprises:

The trace utilization cost function is quantized to the variation on the channel condition information in 2 * 2MIMO pre-coding system first on first code book, and described first code book comprises one or more unitary matrice;

The trace utilization cost function is quantized to the variation on the channel condition information in 2 * 2MIMO pre-coding system second on second code book, and described second code book comprises one or more unitary matrice; And

Repeating described first in an alternating manner quantizes and described second quantification.

2, method according to claim 1 is characterized in that, described channel condition information is a matrix V.

3, method according to claim 2 is characterized in that, described method further comprises uses singular value decomposition to produce described matrix V.

4, method according to claim 2 is characterized in that, described method comprises that further using geometric mean to decompose produces described matrix V.

5, method according to claim 1 is characterized in that, described cost function f (A) is defined by following relational expression:

$f\left(A\right)=\left(\frac{1}{N}\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}{\left|a_{\mathrm{jj}}\right|}^2\right)$

Wherein A is the matrix of N * N, a _IjBe matrix A element (i, j).

6, method according to claim 1 is characterized in that, described method further comprises from first matrix and second matrix and produces described one or more unitary matrice.

7, a kind of system that is used for process communication signals is characterized in that, comprising:

2 * 2MIMO the pre-coding system that comprises one or more circuit, described one or more circuit are used for:

The trace utilization cost function is quantized to the variation on the channel condition information in 2 * 2MIMO pre-coding system first on first code book, and described first code book comprises one or more unitary matrice;

The trace utilization cost function is quantized to the variation on the channel condition information in 2 * 2MIMO pre-coding system second on second code book, and described second code book comprises one or more unitary matrice; And

Repeating described first in an alternating manner quantizes and described second quantification.

8, system according to claim 7 is characterized in that, described channel condition information is a matrix V.

9, system according to claim 8 is characterized in that, described one or more circuit use singular value decomposition to produce described matrix V.

10, method according to claim 8 is characterized in that, described one or more circuit use geometric mean to decompose and produce described matrix V.

Images