A kind of extensive MIMO method for precoding and deviceTechnical field
The present invention relates to wireless communication technology field, more particularly to a kind of extensive MIMO method for precoding and device.
Background technology
The implementation of multiple-input and multiple-output (Multiple-Input Multiple-Output, MIMO) technology will depend on pairIn channel condition information (CSI) utilization, in order to by carrying out precoding in transmitting terminal to improve system transmission performance, transmitting terminalNeed to know channel condition information (Channel Statement Information, CSI), and channel condition information CSI is usualChannel estimation is carried out by receiving terminal using reference sequences to obtain, this usually requires receiving terminal channel condition information CSI and its is anti-Feed transmitting terminal, for calculating suitable precoding or beam forming parameter in transmitting terminal.However, CSI feedback channel hasThe sex-limited design for determining precoding codebook is necessary.In order to reduce feedback quantity, in the situation proposition on high order and low-rankA kind of dicode this W=W by forming for two layers1*W2Method for precoding, W1With W2It is that long-term pre-coding matrix is (that is, sharp respectivelyThe pre-coding matrix calculated with the long-time statistical of channel condition information) with short-term pre-coding matrix (that is, utilize channel condition informationShort term statistics calculate pre-coding matrix).
The long-time statistical characteristic of channel depends primarily on the channel relevancy of channel, and channel relevancy is by aerial array clothThe influence of office.Under traditional multiaerial system (number of antenna elements is less), the linear antenna of antenna array layout generally useArray layout, such as uniform linear array (Uniform Linear Array, ULA)；But under extensive antenna system (my godLine element number is a lot), due to constraint spatially, antenna array layout is more likely to the antenna array layout using plane, such asUniform rectangular array (Uniform Rectangle Array, URA).However, most dicode sheet is both for linear at presentAntenna array layout design, the antenna array layout so for plane, these dicodes can not originally portray letter wellThe long-time statistical characteristic in road, so as to have large effect to system precoding performance.
Although the pre-coding scheme based on dicode sheet is proposed in the prior art, for example existing LTE R8 systems are basesIt is main in 4 antenna codebooks and 8 antenna codebooks of the LTE R10 systems based on dicode the design of mirror transformation Householder designsLevel to be directed to Antenna Design, does not account for vertically being filled in the free degree of space resources to the free degree of antennaDivide and utilize, be especially not efficiently used in the space resources of perpendicular domains, thus in multiple user distributions in same building thingDifferent floors in the case of, these schemes be difficult to support multi-user transmission, be directly used in AAS antenna for base station deployment when, systemPerformance is by degradation.
The content of the invention
The present invention in view of the shortcomings of the prior art, proposes a kind of extensive MIMO method for precoding and device, applied to 4GIn LTE, LTE-A and 5G IMT-2020 GSMs eMBB, utilize what is quantified including supporting vertical direction with horizontal directionPre-coding matrix, the free degree of active antenna system vertical direction can be made full use of, so as to improve the precision of CSI feedback and beSystem handling capacity.
In a first aspect, the present invention proposes a kind of extensive MIMO method for precoding, including：
Channel vector is decomposed into level with vertical dimension channel phase information according to the horizontal dimension of 3D MU-MIMO channel modelsDimensional vector and vertical dimensional vector；
It is the first codebook matrix W for representing broadband or long-term channel characteristics to construct pre-coding matrix W1With representing arrowband or shortSecond code book matrix W of the phase characteristic of channel2Product, first codebook matrix is：
Wherein, Λ, RCLA,H、RCLA,V、RULA,H、RULA,VIt is diagonal matrix, DCLA,H、DCLA,V、DULA,H、DULA,VBe respectively classified asThe positive semidefinite matrix of discrete Fourier transform DFT vectors；
The horizontal codebook set of 3D MU-MIMO systems is stored in transmitting terminal and receiving terminal simultaneously with vertical codebook set,Receiving terminal is grouped to obtain multiple levels by transmitting terminal according to channel condition information CSI is obtained from level, vertical two dimensionsReceiving terminal group and multiple vertical reception ends group, then each horizontal receiving terminal group and vertical reception end group take occur simultaneously two-by-two respectivelyTo multiple alternative optional scheduled reception end set, transmitting terminal is selected from multiple alternative optional scheduled reception end set connect againOne group of receiving end channel quality information CQI sums maximum is used for downlink transfer as the receiving terminal finally dispatched.
Preferably, described Λ, DCLA,H、DCLA,V、DULA,H、DULA,VIt is fixed unit matrix, RCLA,H、RCLA,V、RULA,H、RULA,VBit number be adjustable.
Preferably, it is described when the transmission antenna of the 3D MU-MIMO systems is four antennas and only transmits a code wordChannel independence precoding transmissions are one layer of transmission, or carry out re-transmission transmission using two layers for a code word.
Preferably, when the transmission antenna of the 3D MU-MIMO systems is eight antennas and only transmits a code word, instituteState channel independence precoding transmissions and use four layers or eight layers transmission for one layer or two layers transmission, or for two code words.
Preferably, the first codebook matrix W1In matrix RCLA,H、RCLA,V、RULA,H、RULA,VBe respectively listed in [0,2 π] phaseChosen in the section of position in equally distributed discrete Fourier transform DFT vectors.
Preferably, the first codebook matrix W1In matrix RCLA,H、RCLA,V、RULA,H、RULA,VThe ripple that is formed of each rowIt is adjacent overlapping between beam group subset.
Preferably, when the pre-coding matrix W set in matrix it is more than one when, to different subcarriers in turn according toPositive sequence is using the logm in pre-coding matrix W set according to progress precoding.
Preferably, the pre-coding matrix W is at least one class index RI, the second code book matrix W2It is eachCode word is in the second code book matrix W2Every other code word on distinguished by every layer of at least two beam selection vector.
Preferably, the second code book matrix W2Meet phase-shift keying (PSK) QPSK { 1, -1, j,-j } characteristic, constant modulus property withOrthogonal property, and for selecting the first codebook matrix W1In column vector so as to forming matrix W.
Second aspect, the present invention propose a kind of extensive MIMO pre-coding apparatus, including：
Transmitter, for sending reference signal to receiving device；
Receiver, the pre-coding matrix instruction PMI sent for receiving the receiving device；
Determiner, for determining that the receiving device is based on reference signal use according to the present invention first according to the PMIExtensive MIMO method for precoding any one of aspect constructs the pre-coding matrix W.
Beneficial effects of the present invention：A kind of extensive MIMO method for precoding and device of the present invention, using including supportingThe pre-coding matrix that vertical direction quantifies with horizontal direction, the free degree of active antenna system vertical direction can be made full use of,Solve 4G LTE, the precision and throughput of system of CSI feedback in LTE-A and 5G IMT-2020 GSMs eMBBThe problem of.
Brief description of the drawings
With accompanying drawing, the invention will be further described, but the embodiment in accompanying drawing does not form any limitation of the invention.
Fig. 1 is the extensive embodiment schematic flow sheet of MIMO method for precoding one of the invention.
Fig. 2 is the extensive example structure schematic diagram of MIMO pre-coding apparatus one of the invention.
Embodiment
The present invention is further illustrated with embodiment below in conjunction with the accompanying drawings, and this is presently preferred embodiments of the present invention.
The cross-polarized arrays with vertical and horizontal polarization are set to tend to lead to the transmission of good separation at transmitterPassage, this sends attractive for multithread MIMO.Because use and the block diagonal of block diagonal structure pre-coding matrixThe block diagonal structure matching of channel matrix, so being suitable using the precoding of block diagonal structure.From this view, typicallyThe +/- 45 degree of cross-polarized arrays used are because the two not same polarizations sent in both vertical polarization and horizontal polarization mixClose, then it is block diagonal like that channel matrix, which is likely to not use horizontal and vertical polarization for another example, and this potentially increasesInter-stream interference, and MIMO performances are thus damaged, thus it is considered as unattractive.Accordingly, for +/- 45 degree of cross polarizationsFor situation, block diagonal pre-coding matrix structure is not optimal, but it is very common that it, which is arranged in existing deployment,.
In this case, pre-coding matrix product structure is beneficial, because it is related to resolves into two by pre-coding matrixThe product of individual matrix, cause the newly-generated channel with the trend as block diagonal.Because it is empty effectively to obtain block diagonalIntend channel, so the block diagonal pre-coding matrix W in product structure can be used now1To match its feature.
As shown in figure 1, one embodiment of the invention proposes a kind of building method of pre-coding matrix, including：
Channel vector is decomposed into level with vertical dimension channel phase information according to the horizontal dimension of 3D MU-MIMO channel modelsDimensional vector and vertical dimensional vector；
It is the first codebook matrix W for representing broadband or long-term channel characteristics to construct pre-coding matrix W1With representing arrowband or shortSecond code book matrix W of the phase characteristic of channel2Product W=W1*W2。
For the user terminal UE of the different floors positioned at same building, traditional bidimensional MIMO sometimes can not be spatiallyThey are distinguished, so as to cause them to tend not to enough while be dispatched with same running time-frequency resource, i.e., can not use MU-MIMO.
The horizontal codebook set of 3D MU-MIMO systems is stored in transmitting terminal and receiving terminal simultaneously with vertical codebook set,Receiving terminal is grouped to obtain multiple levels by transmitting terminal according to channel condition information CSI is obtained from level, vertical two dimensionsReceiving terminal group and multiple vertical reception ends group, then each horizontal receiving terminal group and vertical reception end group take occur simultaneously two-by-two respectivelyTo multiple alternative optional scheduled reception end set, transmitting terminal is selected from multiple alternative optional scheduled reception end set connect againOne group of receiving end channel quality information CQI sums maximum is used for downlink transfer as the receiving terminal finally dispatched.
When the transmission antenna of 3D MU-MIMO systems is four antennas and only one code word of transmission, the precoding of channel independence passesDefeated is one layer of transmission, or carries out re-transmission transmission using two layers for a code word；When the transmission antenna of 3D MU-MIMO systems isWhen transmitting for eight antennas and only a code word, channel independence precoding transmissions are one layer or two layers transmission, or are two code wordsUse four layers or eight layers transmission.
When the matrix in pre-coding matrix W set is more than one, different subcarriers is used according to positive sequence in turn pre-Logm in encoder matrix W set is according to progress precoding.
Based on common phase and selection W2Design follow structure for R10 version 8Tx codebook designs, common phase allows at twoPhase adjusted is carried out between polarization group and generates DFT vectors according to two block diagonal matrixs.Due to W2Represent arrowband or short-term letterThe codebook matrix of road characteristic, feedback cycle is shorter, thus excessively depends on W2Common phase regulation is carried out, is unfavorable for feedback and opensPin.
Pre-coding matrix W is at least one class index RI, the second code book matrix W2Each code word in the second code bookMatrix W2Every other code word on distinguished by every layer of at least two beam selection vector.Wherein, the second code book matrix W2Meet phaseKeying QPSK { 1, -1, j,-j } characteristic, constant modulus property and orthogonal property is moved, and for selecting the first codebook matrix W1In rowVector is so as to forming matrix W.
The present embodiment, the horizontal direction at transmitter have to dual polarized antenna, have in vertical direction to dual polarized antenna,They collectively form dual polarization uniform planar aerial array, can spatially distinguish different UE.So, the first codebook matrixWherein, Λ,RCLA,H、RCLA,V、RULA,H、RULA,VIt is diagonal matrix, DCLA,H、DCLA,V、DULA,H、DULA,VBe respectively classified as discrete Fourier transform DFTVector positive semidefinite matrix, well the vector form with antenna-array response match.
Wherein, Λ, DCLA,H、DCLA,V、DULA,H、DULA,VIt is fixed unit matrix, RCLA,H、RCLA,V、RULA,H、RULA,V'sBit number is adjustable.
The present embodiment, W1Represent the codebook matrix of broadband or long-term channel characteristics, W2Represent arrowband or short-term channel behaviorsCodebook matrix.W2It can be used for selection matrix W1In column vector so as to forming matrix W, or for linear weighted combination matrixW1In column vector so as to forming matrix W.The selection operation of wave beam group allows resource block (RB) of the field angle in same sub-bandOn refinement or adjustment so that frequency selectivity pre-coding gain is maximum, and the main origin W of phase-adjusted function1Undertake,Efficiently solve the problem of short-term code book feedback overhead is higher.
In the implementation, to ensure the selection accuracy of each beam vectors group inward flange wave beam, adjacent beams vector is directlyGenerally there is certain overlap.The overlapping of field angle can be favourable for reducing " edge effect ", i.e., prelisted when using subbandWhen code or CSI feedback, it is ensured that public W1Matrix can more preferably be selected for the different resource block (RB) in identical precoding subband.
First codebook matrix W1In matrix RCLA,H、RCLA,V、RULA,H、RULA,VBe respectively listed in [0,2 π] phase intervalChosen in the discrete Fourier transform DFT vectors of even distribution.Also, the first codebook matrix W1In matrix RCLA,H、RCLA,V、RULA,H、RULA,VThe wave beam group subset that is formed of each row between be adjacent overlapping.
As shown in Fig. 2 one embodiment of the invention proposes a kind of extensive MIMO pre-coding apparatus and its corresponding workMake principle, it is specific as follows：
First, the transmitter for sending equipment sends reference signal to receiving device；
Then, the receiver for sending equipment receives the pre-coding matrix instruction PMI that receiving device is sent；
Finally, the determiner for sending equipment determines that receiving device is based on reference signal and constructs the first codebook matrix according to PMIW1, the second code book matrix W2, and by the first codebook matrix W1With the second code book matrix W2It is multiplied, product is the precoding constructedMatrix W.
Finally it should be noted that：Various embodiments above is merely illustrative of the technical solution of the present invention, rather than its limitations；To the greatest extentThe present invention is described in detail with reference to foregoing embodiments for pipe, it will be understood by those within the art that：Its according toThe technical scheme described in foregoing embodiments can so be modified, either which part or all technical characteristic are enteredRow equivalent substitution；And these modifications or replacement, the essence of appropriate technical solution is departed from various embodiments of the present invention technologyThe scope of scheme.