CN107408962A - For determining the method for optimal precoding parameters and the decoding apparatus that prelists of adjustable complexity - Google Patents

For determining the method for optimal precoding parameters and the decoding apparatus that prelists of adjustable complexity Download PDF

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CN107408962A
CN107408962A CN201580078249.7A CN201580078249A CN107408962A CN 107408962 A CN107408962 A CN 107408962A CN 201580078249 A CN201580078249 A CN 201580078249A CN 107408962 A CN107408962 A CN 107408962A
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precoding
value
transmission
function
precoder
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CN107408962A8 (en
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卢卡·罗斯
阿克塞尔·米勒
何高宁
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0452—Multi-user MIMO systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting

Abstract

A kind of value J for being used to determine precoding parameters JoptMethod (400,500,600), the transmission sample sequence s (t) transmitted in multi-antenna systems for precoding, methods described includes：Obtain (401) object function u (J) value, the transmission cycle T based on the transmission sample sequence s (t) for sending precodingT, channel coherence time TCWith precoding performance function f (J), and precoding performance function f (J) characteristic, the transmission cycle TTDepending on T cycle of training for channel estimationTR, for precoding send sample sequence s (t) precoding cycle TPAnd the coherence time T of the channelC；And using (402) optimality criterion to the value of the object function u (J) on the precoding parameters J, to obtain described value Jopt。

Description

For determining the method for optimal precoding parameters and the decoding apparatus that prelists of adjustable complexity
Technical field
This disclosure relates to a kind of method for determining optimal precoding parameters, is passed in multi-antenna systems for precoding The sequence of defeated transmission sample, and a kind of decoding apparatus that prelists of adjustable complexity, for precoding in multi-antenna systems The sequence of the transmission sample of transmission.The invention further relates to the precoding system for realizing variable complexity/variable performance precoding strategy System, using this method to consider the contextual properties of pre-encoding quality and transmission medium, particularly coherence time to carry out most The precoding of excellent ground.Specifically, it is this disclosure relates to maximum for the performance based on the balance between precoder complexity and quality Change the technology of adaptive MIMO precoding.
Background technology
In modern network, the presence of multiple antenna equipments with Long Term Evolution (long term evolution, LTE) deployment of infrastructure and come true.In next generation communication system (i.e. 5G networks), this phenomenon certainly will drastically increase Add, so as to generate extensive multiple-input and multiple-output (massive multiple input multiple output, MaMIMO) system.In such a system, the quantity of the transmitting antenna at base station (base station, BS) place is much larger than reception The total quantity of antenna.Typically in mimo systems, particularly in MaMIMO, precoding occupies significant status.It is most common Precoding type includes maximum rate transmitting (maximum ration transmission, MRT) (also referred to as matched filter (matched filter, MF)), the signal that it makes to receive is than noise power (signal to noise power, SNR) most Bigization, ZF (zero-forcing, ZF), it makes the minimum interference between not cocurrent flow, and regularization ZF (regularized zero forcing, RZF) (also referred to as maximum mean square error (maximum mean square error, MMSE) transmitted with Wiener filter (Wiener filter)), it increases signal noise and adds interference than (signal to noise Plus interferenceratio, SINR).
Different precoding strategies produces different performances in handling capacity, and needs the different calculating time.Most The complexity of high-performance (in handling capacity) precoding and the quantity of transmitting antenna are closely related.With finite computational abilities, In the system that limited coherence time and a large amount of transmitting antennas are characterized, this severely limits the performance of network.Channel condition may Change due to mobility, this can change channel statistical and relevant duration again in turn.Especially, coherence time changes It may be influenceed by the scheduling of highly mobile user, or by the uncontrollable modification to the object velocity around receiver Influence.In this case, fixed complexity pre-coding scheme can suffer from serious limitation.
In exemplary downlink MaMIMO systems as shown in Figure 1, base station (base station, BS) is equipped with M Individual antenna, and its service K reception antenna, wherein M ＞ ＞ K altogether, for from multiple user equipment (user Equipment, UE) reception signal.In order to successfully serve different users, BS needs to retrieve channel matrix Then its precoder is calculated, is represented by alphabetical w.All standard precoders (for example, MMSE, MF) used in document by Some fixed functions of channel matrix limit.Here fixation refers to the fact that their complexity can not be adjusted.For example, most may be used One of precoding strategy of implementation is referred to as RZF transmission, and its formula is：
Here, z represents regularization factors, generally uses noise variance divided by transmit power, IKRepresent dimension K unit square Battle array, and β is the normalization factor for ensureing the power budget to be observed.It can prove that this tactful complexity is at a relatively high, and Its with transmitting antenna M number and reception antenna number K square and linear increase.
In view of its high-performance, it is RZF precoders to be in the following assumed to for the baseline of precoding.However, institute's exhibition The reasoning opened is consistent with any kind of linear precoder with fixed complexity.
In the single coherence time shown in Fig. 2, BS must complete following steps：(i) training is completed to obtain channel square Battle array；(ii) precoder is calculated；(iii) send and terminate until coherence time.Therefore, coherence time TCIt can be divided into for three weeks Phase：Cycle of training TTR, precoding cycle TPWith transmission cycle TT, and then have TC=TTR+TP+TT.Cycle of training be it is fixed, it Channel status is obtained depending on Systematic selection, and is considered as fixed for hereafter.On the contrary, compole during precoding The earth depends on selected precoder.In T cycle of trainingTREnd 210 at, obtain channel matrix H.In the precoding cycle TPEnd 212 at, the first symbol is encoded and sent.
Obviously, the overall performance of system depends not only on the performance of precoder, and depends on its complexity.It is logical Often, higher complexity can bring the higher code performance that prelists, and but have the longer precoding time.If contemplate variable relevant Between or hardware variable performance, then be readily seen fixed complexity (and then fixed precoding time) strategy and be not suitable for MaMIMO systems System.If for example, TC＜ TTR+TP, then no time is exclusively used in transmitting, and the total throughout of system will be equal to 0.
In general, problem is to maximize object function, and it can be expressed as：
Wherein f () is the yardstick of precoder w performance, for example, it can be average SINR ranks.Symbol (x)+Represent maximum (x, 0).
In MaMIMO systems, one of technology most carried out be for example by M.Joham, K.Kusume, M.H.Gzara, W.Utschick, and J.A.Nossek " are being used for the transmission Wiener filter of the downlink of TDD DS-CDMA systems The years of (Transmit Wiener Filter for the Downlink of TDD DS-CDMA Systems) " 2002 ISSSTA collects, the RZF of 2002 year 1 page number 9-13 of volume descriptions.The technology balances interference and useful signal is maximized averagely SINR negative effect.However, the solution requires the evaluation of following matrix：
Be possible to show total complexity of this method, and and then the precoding time with M and K square and linearly Increase.
In order to exchange complexity, M ü ller, A., A.Kammoun, E. for performanceAnd M.Debbah, " based on more The linear predictive coding of item formula expansion：Reduce complexity (the Linear Precoding Based in extensive MIMO Polynomial Expansion：Reducing Complexity in Massive MIMO) " propose Representation theorem exhibition Open the realization of (truncated polynomial expansion, TPE).It is similar to flowing according to the matrix operation of equation (1) The power sequence for the fixed size realized in journey, such as according to precoder flow 300 as shown in Figure 3.This solution Code performance is prelisted to shorten the precoding time of fixed amount by being reduced in terms of SINR.
Precoder flow 300 include a series of memory blocks 321 based on channel estimation H, 322a, 322b, 323a, 323b；For realizing the weighting filter (not shown in Fig. 3) and processor 301,302,303 of filter function.Processor includes Multiple J processing cores or pre-encoded blocks 301,302,303, it is configured to parallel processing driving and sends sample sequence 302, s (t) passes through A series of memory block with provided at the tap 341,342,343 of a series of memory block a series of power coefficient 331, 332、333.Processor 301,302,303 is based on filter function ∑ wiA series of power coefficient series 331,332,333 is entered Row is filtered to provide the transmission sample y (t) of precoding (not shown in Fig. 3).Precoder flow 300 includes being coupling in each depositing Multiple memory latency units 312,313 between reservoir block, for postpone a series of memory block tap 341,342, Signal at 343.
However, this solution (referring to Fig. 3) does not consider that wherein coherence time is not situation about being a priori known that, and And change with the user of scheduling, or do not consider that wherein different hardware ability is available situation.
The content of the invention
It is used to improve the precoding in mimo antenna system relative to computation complexity it is an object of the invention to provide a kind of The concept of efficiency, it is not a priori to be known that or wherein different hardware ability is available feelings especially for wherein coherence time Condition.
The purpose is realized by the feature of independent claims.Further way of realization dependent claims, specification It is obvious with accompanying drawing.
The present invention is by limiting the precoder of family's variable complexity come regarding to the issue above.This variable complexity is adjusted The whole balance to prelist between code performance and complexity, so as to improve transmission quality.
The basic conception described in the disclosure is according to herein below：In (extensive) multiple antennas network, calculate pre- The time that encoder is spent reduces the time useful to data transfer.On the other hand, the complexity of precoder is increased, i.e., The time is calculated, better performance can be produced during the transmission.Optimal tradeoff depends primarily on complexity, using more complicated pre- Performance gain, relevant duration and the hardware capabilities that encoder obtains.Based on power series, i.e. channel multiplies the weighting of vector product The system for calculating the technology of time for determining optimal precoder and realizing it is described with, the disclosure.And then it is derived use In it is determined that the algorithm of optimal balance, and reality utilize these optimal settings to be used for the system that precoding sends sample sequence.Should The precoding time can be expressed as the product for (limited) amount that calculate before being transmitted.It is available not at the same level according to base station Other information, introduce different solutions.
In order to which the present invention is described in detail, following term, abbreviation and symbol will be used：
M：Antenna amount at transmitter.
K：The antenna amount of receiver is (for simplicity, it is contemplated that the receiver of an antenna；However, the present invention is suitable For the receiver with multiple antennas).
TC：Coherence time
J：The quantity of encoding block
BS：Base station
H：Channel matrix
MIMO：Multiple-input and multiple-output
RZF：Regularization ZF
TPE：Representation theorem deploys
MF：The wave filter of matching
UE：User equipment
LTE：Long Term Evolution
MaMIMO：Extensive MIMO
MRT：Maximum rate is launched
SNR：Signal-to-noise power ratio
ZF：ZF
MMSE：Least mean-square error
SINR：Signal noise adds interference ratio
TTR：Cycle of training
TP：The precoding cycle
TT：Transmission cycle
In the following, it is described that the apparatus and method that can be applied in mimo antenna system using precoding technique. MIMO is for increasing radio link capacity using multiple transmittings and reception antenna so as to develop the method for multipath propagation. MIMO refers specifically to be used to send and receive more than one in same time and same wireless radio channel via multipath propagation The practical technique of individual data-signal.Precoding is the vague generalization of beam forming, to support the multithread or more in mimo wireless communication Layer transmission.In Point-to-Point system, precoding means to launch multiple data flows from transmitting antenna with independent and appropriate weight, So that link throughput is maximized at receiver output.In multiuser MIMO, data flow is intended to for different users, And some yardsticks of total throughout are maximized.
According in a first aspect, the present invention relates to a kind of value J for being used to determine precoding parametersoptMethod, for precoding The transmission sample sequence transmitted in multi-antenna systems, methods described include：The value of object function is obtained, based on pre- for sending The transmission cycle of transmission sample sequence, the coherence time of channel and the precoding performance function of coding, and precoding performance function Characteristic, the transmission cycle depends on the cycle of training for channel estimation, for sending sample sequence described in precoding Precoding cycle and the coherence time of the channel；And application optimality criterion is on the precoding parameters The value of the object function, to obtain described value Jopt。
Because optimal precoding parameters are applied to precoding, this method improves mimo antenna relative to computation complexity The code efficiency that prelists in system.Said in the sense that the value of its optimization object function, relative to default optimality criterion, such as Minimum value, maximum or predetermined threshold, the precoding parameters applied to precoding are optimal.Because precoding parameters J value JoptBe not it is predetermined enter rather than it is fixed, but determined in operation based on coherence time, coherence time it is any Change is all considered, and is therefore reflected in determination value JoptIn.This provide flexibly, efficiently and accurately send sample sequence Precoding.
In the first possible way of realization of the method according to first aspect, the transmission cycle is with following condition It is at least one and reduce：Increase the cycle of training, increase the precoding cycle.
According to first aspect in itself or the method according to the first way of realization of first aspect the second possible reality In existing form, the characteristic of the precoding performance function includes the precoding performance function, with precoding parameters list Adjust increase.
Know that the behavior of precoding performance function provides an advantage in that, even in accurate precoding performance function not Value J can also be determined in the case of knowingopt。
Preferably, precoder parameter is natural number.Offer the advantage that, in order to calculate optimal precoding ginseng Number, it is only necessary to a small amount of calculating.
According to first aspect in itself or may according to the 3rd of the method for any foregoing way of realization of first aspect the In way of realization, the sum of the pre-encoded blocks of the precoding parameters instruction precoder, and described value JoptIndicate to be used in advance Encode the optimal number of precoder described in the transmission sample sequence.
In other words, the amount of the complexity for the precoding that precoder parameter corresponds under mounting hardware ability.On this Hereinafter, the optimal number instruction of pre-encoded blocks will be activated for sending the core of the processor of the parallel processing of sample sequence Number, to realize the maximally effective precoding of given sequence in terms of time and complexity.Offer the advantage that, for Given hardware, can determine makes the efficiency of available hardware maximumlly optimal precoding parameters.
According to first aspect in itself or may according to the 4th of the method for any foregoing way of realization of first aspect the In way of realization, methods described includes：Sample sequence is sent described in precoding, based on the optimal precoder parameter；And The transmission sample sequence through precoding is sent by the channel.
Offer the advantage that, be optimal in precoding described in precoding aspect of performance.When based on optimal precoding When the precoding of device parameter sends sample sequence, the code efficiency that prelists in mimo antenna system is carried relative to computation complexity Height, particularly coherence time is not in the case of being a priori known that or wherein having different hardware capabilities available wherein.It is real Now flexible, adaptable precoding.
According to first aspect in itself or may according to the 5th of the method for any foregoing way of realization of first aspect the In way of realization, the object function is the transmission cycle and by the coherence time normalized precoder performance The product of function.
Offer the advantage that, optimal precoding parameters are for increased transmission cycle and/or precoder performance Function and coherence time for reduction are optimal.
According to first aspect in itself or any foregoing way of realization method according to first aspect the 6th may In way of realization, using optimality criterion to object function value the step of include：In the precoding performance function to close In the case of form or conduct estimation are available, technology is maximized by applied mathematics, maximizes the object function；And institute State precoding performance function using closing form or as estimate it is disabled in the case of, by using heuristic technique, maximizing The object function.
Offer the advantage that, depending on the available form of precoding performance function, different prelist can be applied Code strategy.Therefore, this method can neatly be applied.
In the 7th possible way of realization of the method for the 6th way of realization according to first aspect, using the inspiration Formula technology includes：Relative to the value value that continuously object function described in evaluation obtains for increasing the precoding parameters, Zhi Daosuo The difference stated between two successive values of object function is less than threshold value.
Provided an advantage in that using this heuristic technique, in precoding performance function using closing form or as estimating Count it is disabled in the case of, optimal precoding parameters can also be determined.
According to first aspect in itself or may according to the 8th of the method for any foregoing way of realization of first aspect the In way of realization, the Signal to Interference plus Noise Ratio of the precoding performance function based on reception.
This provide it is such a little, the signal of change precoding performance function that evaluation receives can be passed through.
In the 9th possible way of realization of the method for the 8th way of realization according to first aspect, the precoding Energy Signal to Interference plus Noise Ratio of the function based on the reception adds 1 logarithmic function.
Offer the advantage that, the signal that can be received by evaluation simultaneously applies some simple mathematics, calculates pre- Coding efficiency function.
According to first aspect in itself or may according to the tenth of the method for any foregoing way of realization of first aspect the In way of realization, the precoding performance function is received in the feedback signal from mobile terminal.
Offer the advantage that, precoding performance function can use and need not have been calculated.
According to first aspect in itself or can according to the 11st of the method for any foregoing way of realization of first aspect the In energy way of realization, the value of the precoding performance function is received in the feedback signal from mobile terminal.
Offer the advantage that, can not estimate even if precoding performance function is both unavailable, can also be accurately Determine the value J of precoding parametersopt。
According to second aspect, prelisted decoding apparatus the present invention relates to one kind, including：Precoder, for precoding at more days The transmission sample sequence transmitted in linear system system, wherein it is adjustable that the amount of the complexity of the precoder, which is based on precoding parameters, 's；Processor, for by application optimality criterion on the precoding parameters object function value, it is determined that being used for institute State the value J of the precoding parameters of precoderopt；Wherein described processor is arranged to determine the object function, base It is described in the transmission cycle of transmission sample sequence for sending precoding, the coherence time of channel and precoding performance function Transmission cycle depends on the cycle of training for channel estimation, precoding cycle and the letter of sample sequence is sent for precoding The coherence time in road.
This decoding apparatus that prelists improves the code efficiency that prelists in mimo antenna system relative to computation complexity, because Optimal precoding parameters are applied in precoder.Said in the sense that the value of its optimization object function, relative to it is default most Dominance criterion, the precoding parameters applied to precoding are optimal.Because precoding parameters J value JoptIt is not predetermined Be less fixed, but determined in operation based on coherence time, so any change of coherence time is all considered, And therefore it is reflected in determination value JoptIn.A kind of flexible, efficient and accurate precoder is provided, it allows to sending sample This sequence carries out adaptability precoding, while take into account the change of a priori unknown coherence time.
By applying optimal precoding parameters, it is possible to reduce the amount of the complexity for the decoding apparatus that prelists, so as to improve precoding Efficiency.
In the first possible way of realization of the decoding apparatus that prelists according to second aspect, the processor is arranged to phase Value for increasing the precoding parameters continuously calculates the value of the object function, until two companies of the object function Difference between continuous value is less than threshold value.
Provided an advantage in that using this heuristic technique, in precoding performance function using closing form or as estimating Count it is disabled in the case of, optimal precoding parameters can also be determined.
According to the third aspect, the present invention relates to a kind of multi-antenna base station, including：Set according to the precoding of second aspect in itself The decoding apparatus that prelists of first way of realization standby or according to second aspect, wherein the precoder is arranged to precoding institute Transmission sample sequence is stated, based on the identified value of the precoding parameters；And transmitter, it is configured to the letter Road sends the transmission sample sequence of precoding.
In this multi-antenna base station, in precoding aspect of performance, precoding is optimal.When based on precoder parameter Determination value to send sample sequence carry out precoding when, relative to computation complexity, the code efficiency that prelists of multi-antenna base station It is improved, particularly coherence time is not a priori to be known that or wherein have the available situation of different hardware capabilities wherein Under.
According to fourth aspect, the present invention relates to a kind of pre-coding system, including：Precoder, it is used to lead to for precoding Cross the transmission sample sequence of some transmission medium；And processor, using according to first aspect method in itself or according to first The method of any form of implementation of aspect, for providing variable precoding strategy to the precoder, with relative to described The pre-encoding quality and contextual properties of transmission medium, especially with respect to coherence time, optimally send sample described in precoding This sequence.
Such pre-coding system provides an advantage in that processor is able to carry out the calculation for determining optimal balance Method, then set by the precoder for carrying out precoding to transmission sample is actual using optimal balance.Processor can be Optimal balance is realized during off-line operation or during on-line operation.This is provided in continually changing environment for the realization of system The flexibility of height.Depending on the change of coherence time, this variable precoding strategy is to fit in complexity and aspect of performance Answer.High flexible and efficient precoding system are caused using this variable complexity/variable performance precoding strategy.
Brief description of the drawings
Further embodiment of the present invention will be described with reference to the following drawings, wherein：
Fig. 1 shows the schematic diagram for showing extensive mimo system 100；
Fig. 2 shows the schematic diagram 200 utilized of the coherence time of display channel；
Fig. 3 shows the block diagram for the example 300 that the flow of display precoder is realized；
Fig. 4 shows the transmission that is used to determine for precoding in multi-antenna systems transmit of the display according to way of realization The schematic diagram of the method 400 of the optimal precoding parameters of sample sequence；
Fig. 5 shows the flow chart that is used to determine the method 500 of optimal precoding parameters of the display according to way of realization；
Fig. 6 shows the flow chart that is used to determine the method 600 of optimal precoding parameters of the display according to way of realization；
Fig. 7 shows block diagram of the display according to the decoding apparatus 700 that prelists of way of realization；And
Fig. 8 shows performance map 800 of the display according to the performance of the exemplary decoding apparatus that prelists of way of realization.
Embodiment
In detailed description below, accompanying drawing system made reference and form its a part, and wherein by showing The mode of the open specific aspect that can put into practice the disclosure is shown.It should be appreciated that without departing from the scope of the disclosure, Other aspects can be utilized and structure or logic can be changed.Therefore, detailed description below is understood not to restricted , and the scope of the present disclosure is defined by the following claims.
It should be appreciated that the note that the method with reference to described by is made sets for being arranged to perform corresponding to this method Standby or system can also be set up, and vice versa.If for example, describing specific method and step, corresponding equipment can wrap The unit for performing described method and step is included, even if such unit is not expressly depicted or shown in figure. Moreover, it will be appreciated that unless otherwise specified, the feature of various illustrative aspects described herein can be combined with each other.
In the following detailed description, with reference to extensive MIMO downlink scenarios.In extensive MIMO downlink scenarios In, the quantity of the antenna of base station is much larger than the quantity of reception antenna, i.e. M ＞ ＞ K.Explained to simplify, do not consider channel here Difference between matrix and the channel matrix of estimation.However, whenever channel matrix is employed at base station or receiver, all make With the channel matrix of estimation.Estimate the method for channel matrix outside the scope of the present disclosure.
In the following detailed description, with reference to the system model that channel matrix H is converted by using pre-coding matrix W. In such system model, x (t) can represent the information vector in moment t, and y (t) can represent the hair in moment t The vector sent.They can generally be linked by relation y (t)=Wx (t), and wherein W is pre-coding matrix.Pre-coding matrix can be with Evaluation, following different strategy.For example, W=HHIt is the wave filter (also referred to as maximum rate transmitting, MRT) of matching.It is general next Say, W is the function of channel matrix H.Each coherence time, channel matrix changes and it is reevaluated, and then precoder Change.Base station needs " precoding ", i.e. in each coherence time evaluation active matrix W.Calculate what this pre-coding matrix was spent Time cannot be used for sending (because matrix is also unavailable), as shown in Figure 2.This be for extensive MIMO it is especially problematic, Because the large scale of channel matrix means the big calculating time.If for example, using according to " M.Joham, K.Kusume, M.H.Gzara, W.Utschick, and J.A.Nossek " the transmission wiener filter for the downlink of TDD DS-CDMA systems 2002 annual ISSSTA of ripple device " collects, and the RZF in 2002 years 1 page number 9-13 " of volume, computation complexity is approx increased to MK2+K3 (that is, its with the amount of reception antenna and more than square grade increase).If it is considered to coherence time can be 5 μ s magnitude, very It is readily seen how this calculating can have a strong impact on systematic function.
Fig. 4 shows the transmission that is used to determine for precoding in multi-antenna systems transmit of the display according to way of realization The schematic diagram of the method 400 of the optimal precoding parameters of sample sequence.
Method 400 includes determining 401 object function u (J) and 402 optimality criterions of application to the object function u on J (J).It is the transmission cycle T based on the transmission sample sequence s (t) for sending precoding to determine 401 object function u (J)T, base In the coherence time T of channelCAnd it is based on precoding performance function f (J).Precoding performance function f (J) joins depending on precoding Number J.As shown in Fig. 2 is exemplary, transmission cycle TTDepending on T cycle of training for channel estimationTR, for precoding send sample This sequence s (t) the precoding cycle T P and coherence time T of channelC.Using 402 optimality criterions to object function u (J) It is to obtain optimal precoding parameters J on precoding parameters Jopt。
Transmission cycle TTIt can reduce with least one in following condition：Increase T cycle of trainingTR, increase prelists Code cycle TP.Precoding performance function f (J) can be increased monotonically with precoding parameters J.Object function u (J) can be transmission week Phase TTWith by coherence time TCThe product of normalized precoder performance function f (J).Precoder parameter J can be nature Number.Precoder parameter J may correspond to the amount of the complexity of the precoding of mounting hardware ability.
Method 400 can also include：Based on optimal precoder parameter J, precoding sends sample sequence s (t), for example, As described by above for Fig. 3 or below with respect to described by Fig. 7；And the transmission sample sequence s of precoding is sent by channel (t).Method 400 can also include：Precoding performance function f (J) using closing form or as estimate it is available in the case of, lead to Applied mathematics maximization technology is crossed, maximizes object function u (J)；And precoding performance function f (J) with closing form or As estimate it is disabled in the case of, by using heuristic technique, maximizing the object function u (J), for example, as following Described in reference picture 5 and Fig. 6.It can include using heuristic technique：Mesh is continuously calculated relative to increase precoding parameters J value Scalar functions u (J) value, until the difference between object function u (J) two successive values is less than threshold value, for example, such as following reference picture Described in 5 and Fig. 6.Precoding performance function f (J) can the Signal to Interference plus Noise Ratio based on reception, for example, as described below. Precoding performance function f (J) can add 1 logarithmic function based on the Signal to Interference plus Noise Ratio of the reception.Precoding Energy function f (J) can be received in the feedback signal from mobile terminal.
Object function can export as described below.Provided according to disclosed method and equipment by the matter of precoding strategy Measure the technology that f (w) is suitable to the length of coherence time.Generally, precoder can be written as：
Wherein term ωiIt is the suitable parameter (matrix of appropriate size or scalar) in order to maximize f (w) and calculate. During transmission time, some vectors of w precodings are used.Time index is represented with n (or t), the hair of precoding is represented with x (n) The amount of being sent to, and uncoded transmission signal is represented with s (n), it can obtain
By limiting following intermediate quantity：
(4) can be expressed as
Therefore, the vectorial evaluation of coding is reduced to intermediate vectorEvaluation, and precoder performance Clearly depend on parameter J.That is, larger J values correspond to the more accurately evaluation of precoder, but also correspond to more The long precoding time.In fact, the quantity of the operation needed for precoding is with parameter J linear increases, and precoder performance f (w) can be J non-decreasing function.Because precoder can be positively identified by parameter J, and its performance can also be known Not, in order to simplify symbol, f (w (J)) can be expressed as f (J).Therefore, in the disclosure, can be with selection parameter J to maximize Following object function：
Fig. 5 shows the flow chart that is used to determine the method 500 of optimal precoding parameters of the display according to way of realization.
Method 500 is since first piece 501, wherein alphabetical Ω represents the ratio between single operation complexity and hardware speed Rate, in other words, it represents to calculate the time needed for single operation.In second piece 502, factor I is evaluated as (TC- TP)/TC, i.e. coherence time TCWith precoding time (or cycle) TP difference divided by coherence time TC.In the 3rd piece 503, check Whether f (J), i.e. precoding performance function is available or can be estimated (for example, passing through feedback) with closing form.If f (J) is with envelope Close form to can use or can be estimated, in the 4th piece 504, calculating makes object function u (J)=(TT/TC) the maximized value J of f (J), Transmission cycle divided by correlation time and it is multiplied by precoding performance function f (J).If such function f (J) can not be with enclosed shape Formula is available and can not be estimated, in the 5th piece 505, according to applying heuristic technique below：Value relative to increase J is continuous Ground calculates u (J) value, until the difference between u (J) two successive values is less than threshold value.It may then pass through and use what is found Or the J calculated value applies precoding (not shown in Fig. 5).
As shown in figure 5, function f (J) property and available information, can calculate optimal J in two different ways.In f (J) in the case of can use or can be estimated with closing form, standard maximum technique maximized function u can be used (J).Single variable function is maximized to be easier, certainly,, can in the case of especially complex function as reserved regimen With using heuristic technique, such as exhaustive search or trial and error pricing.Such solution is possible, because J is naturally (can Can be small) number.
Resulting optimal J is substantially coherence time correlation.Therefore, whenever changing coherence time, it is required for weight New initialization.
Fig. 6 shows the flow chart that is used to determine the method 600 of optimal precoding parameters of the display according to way of realization.
Method 600 is since corresponding to first piece 501 of described above with reference to Fig. 5 first piece 501.With lower frame 502, 503rd, 504 can correspond respectively to above with reference to the frame 502,503,504 described by Fig. 5.If above-mentioned function f (J) is not to seal It is available and can not be estimated to close form, in the 5th piece 605, according to applying heuristic technique below：Test value, such as J=1 It is applied to precoding parameters J.Then, in the 6th piece 606, precoding is applied by using J applicable value.Subsequent In 7th piece 607, check whether precoding parameters J is test value.If J is not test value, the 6th piece 606 is repeated.If J is Test value, in the 8th piece 608, check whether object function u (J) currency is more than u (J) preceding value.If answer is Certainly, in the 9th piece 609, precoding parameters J increases, for example, 1 (or any other value) of increase：J=J+1, and method 600 according to the 6th piece of 606 progress precoding.If answer is no, method 600 directly carries out precoding according to the 6th piece 606.
As shown in fig. 6, according to function f (J) property and available information, optimal J can be calculated in two different ways. In the case where f (J) can use or can be estimated with closing form, standard maximum technology can be used to make function u (J) Maximize.Single variable function is maximized to be easier, certainly, as reserved regimen, in the case of especially complex function, Heuristic technique, such as exhaustive search or trial and error pricing can be applied.Such solution is possible, because J is natural (being probably small) number.In the case of this function is disabled, method 600 uses trial-and-error method.It may begin at value J：= 1, and u (1) is obtained, then in next coherence time, it attempts u (2).If u (2)≤u (1), optimal J is equal to 1, if u (2) ＞ u (1), then algorithm attempt J：=3, and obtain u (3).Now, if u (3)≤u (2), optimal J is equal to 2, otherwise algorithm Increase J is kept to provide the false code for realizing this algorithm in table 1.
Table 1：The optimal J of trial and error algorithm evaluation false code
Fig. 7 shows block diagram of the display according to the decoding apparatus 700 that prelists of way of realization.The decoding apparatus 700 that prelists can be realized Above with reference to the method 400,500, one of 600 described in Fig. 4-6.
The decoding apparatus 700 that prelists includes precoder 701 and processor 707.Precoder 701, precoding is in multiple antennas system The transmission sample sequence s (t) 702 transmitted in system, the wherein amount of the complexity of precoder 701 are based on precoding parameters J can Adjustment.
Precoder 701 can include a series of memory block 705, for example, corresponding to as discussed above concerning described by Fig. 3 Memory block 321,322a, 322b, 323a, 323b.The output 721 of wherein a series of memory block 705 is realized with being used for The weighting filter 703 of filter function couples sends sample y (t) 704 to calculate precoding.
Processor 707, to the object function u (J) on precoding parameters J, determines precoding by application optimality criterion The optimal precoding parameters J of device 701opt, for example, as explained above with described in Fig. 4-6.Processor 707 is configured for being used for Send the transmission sample sequence s (t) of precoding transmission cycle TT, channel coherence time TCWith precoding performance function f (J), Determine the object function u (J).Precoding performance function f (J) depends on precoding parameters J.Transmission cycle TTDepending on for T cycle of training of channel estimationTR, for precoding send sample sequence s (t) precoding cycle T P and channel it is relevant when Between TC。
Processor 707 can relative to increase precoding parameters J value continuously calculating target function u (J) value, until Difference between object function u (J) two successive values is less than threshold value, for example, as discussed above concerning described in Fig. 5 and Fig. 6.
The decoding apparatus 700 that prelists can be realized in multi-antenna base station, for example, equipment BS as shown in Figure 1, it includes prelisting Decoding apparatus 700, wherein precoder 701 are configured for optimal precoding parameters JoptPrecoding sends sample sequence s (t).Base station can also include transmitter, for sending the transmission sample sequence s (t) of precoding by channel.
Fig. 8 shows performance map 800 of the display according to the performance of the exemplary decoding apparatus that prelists of way of realization.
Fig. 8 shows the result of numerical simulation.Consider precoding performance function f (J)=loge(1+SINR).In Fig. 7 Description prelist decoding apparatus 700 on the machine of N=6 core for being equipped with exemplary amounts with C=1GHz exemplary speed Realize.The mimo system simulated has K=80 reception day of M=200 transmitting antenna of exemplary amounts and exemplary amounts Line, it is per second to produce about 256K operation.
First curve 801 depict on the SNR in units of dB for precoding parameters J=3 in units of nats Spectrum efficiency.Second curve 802 depict on the SNR in units of dB for precoding parameters J=2 using nats to be single The spectrum efficiency of position.3rd curve 803 depict on the SNR in units of dB for precoding parameters J=4 using nats as The spectrum efficiency of unit.Fig. 8 shows the increase J value not always improvement of the overall performance of generation system, and select optimal J can Significantly to improve systematic function.
The disclosure also supports the computer program product for including computer-executable code or computer executable instructions, When being performed, trigger at least one computer to perform and calculate the step of being described herein, particularly above with reference to described in Fig. 4 to 6 Method 400,500 and 600.Such computer program product can include readable storage medium storing program for executing, be stored thereon with for calculating The program code that machine uses.Program code can be performed above with reference to the method 400,500,600 described in Fig. 4 to Fig. 6.
Although the specific feature or aspect of the disclosure are disclosed relative to the only one in some realizations, so Feature or aspect can be combined with one or more further features or aspect of other realizations, this is for any given Or application-specific is probably desired and favourable.In addition, used in detailed description or claim term " comprising ", " having ", " carrying " or other modifications, such term are intended to have pardon in a manner of similar to term " comprising ".This Outside, term " exemplary ", " such as " and " for example " merely mean that as an example, rather than optimal or optimal.It can make With term " coupling " and " connection " and derivative.It should be appreciated that these terms can serve to indicate that two element coordination with one another Or interaction, it is direct physical contact or electrical contact but regardless of them, or they are not directly contacted with each other.
While there have been illustrated and described particular aspects, but it will be appreciated by the skilled addressee that do not taking off In the case of from the scope of the present disclosure, various replacements and/or equivalent realize can substitute shown or described specific aspect.This Application is intended to cover any modification or change of particular aspects in greater detail herein.
Although the element in following claims is enumerated with the particular order with respective markers, unless claims state The particular order for realizing some or all of those elements is implied in addition, and not so those elements are not necessarily intended to be limited For with the particular order.
According to above-mentioned teaching, many replacements, modifications and variations will be apparent for those skilled in the art.When So, it will be readily appreciated by those skilled in the art that in addition to those described herein, many applications of the present invention be present.Although The present invention is described with reference to one or more specific embodiments, but those skilled in the art recognize, are not departing from In the case of the scope of the present invention many changes can be carried out to it.It will thus be appreciated that in appended claims and its it is equal In the range of thing, the present invention can be implemented in a manner of different from what is specifically described herein.

Claims (16)

  1. A kind of 1. value J for being used to determine precoding parameters JoptMethod (400,500,600), for precoding in multiple antennas system The transmission sample sequence s (t) transmitted in system, methods described include：
    Obtain (401) object function u (J) value, the transmission cycle based on the transmission sample sequence s (t) for sending precoding TT, channel coherence time TCWith precoding performance function f (J), and precoding performance function f (J) characteristic, the transmission week Phase TTDepending on T cycle of training for channel estimationTR, for described in precoding send sample sequence s (t) the precoding cycle TPAnd the coherence time T of the channelC；And
    Using (402) optimality criterion to the value of the object function u (J) on the precoding parameters J, with described in acquisition Value Jopt。
  2. 2. according to the method for claim 1 (400,500,600),
    Wherein described transmission cycle TTReduce with least one in following condition：Increase T cycle of trainingTR, increase The precoding cycle TP。
  3. 3. method (400,500,600) according to claim 1 or 2,
    The characteristic of wherein described precoding performance function f (J) includes the precoding performance function f (J), with precoding Parameter J is increased monotonically.
  4. 4. the method (400,500,600) described in one in preceding claims, wherein the precoding parameters J is indicated The sum of the pre-encoded blocks of precoder, and described value JoptIndicate the institute for being used for transmission sample sequence s (t) described in precoding State the optimal number of the pre-encoded blocks of precoder.
  5. 5. the method (400,500,600) described in one in preceding claims, including：
    Sample sequence s (t), the described value J based on the precoder parameter J are sent described in precodingopt；And
    The transmission sample sequence (s (t)) of the precoding is sent by the channel.
  6. 6. the method (400,500,600) described in one in preceding claims,
    Wherein described object function u (J) is the transmission cycle TTWith by the coherence time TCThe normalized precoder Performance function f (J) product.
  7. 7. the method (400,500,600) described in one in preceding claims, wherein using optimality criterion to institute The step of stating object function u (J) value, including：
    The precoding performance function f (J) using closing form or as estimate it is available in the case of, it is maximum to pass through applied mathematics Change technology, maximize the object function u (J)；And
    The precoding performance function f (J) using closing form or as estimate it is disabled in the case of, by application it is heuristic Technology, maximize the object function u (J).
  8. 8. according to the method for claim 7 (400,500,600), wherein including using the heuristic technique：
    Relative to the value value that continuously object function u (J) described in evaluation is obtained for increasing the precoding parameters J, until described Difference between object function u (J) two successive values is less than threshold value.
  9. 9. the method (400,500,600) described in one in preceding claims,
    Wherein described Signal to Interference plus Noise Ratio of the precoding performance function f (J) based on reception.
  10. 10. according to the method for claim 9 (400,500,600),
    Wherein described Signal to Interference plus Noise Ratio of the precoding performance function f (J) based on the reception adds 1 logarithmic function.
  11. 11. the method (400,500,600) described in one in preceding claims,
    Wherein described precoding performance function f (J) is received in the feedback signal from mobile terminal.
  12. 12. the method (400,500,600) described in one in preceding claims,
    The value of wherein described precoding performance function f (J) is received in the feedback signal from mobile terminal.
  13. Decoding apparatus (700) 13. one kind prelists, including：
    Precoder (701), the transmission sample sequence s (t) transmitted in multi-antenna systems for precoding, wherein described prelist The amount of the complexity of code device is adjustment based on precoding parameters J；
    Processor (707), for by applying optimality criterion to the object function u's (J) on the precoding parameters J Value, determine the precoding parameters J of the precoderoptValue Jopt,
    Wherein described processor (707) is arranged to determine the object function u (J), based on the hair for sending precoding Deposit sequence s (t) transmission cycle TT, channel coherence time TCWith precoding performance function f (J), the transmission cycle TT Depending on T cycle of training for channel estimationTR, for described in precoding send sample sequence s (t) precoding cycle TPWith And the coherence time T of the channelC。
  14. 14. the decoding apparatus that prelists (700) according to claim 13,
    Wherein described processor (707) is arranged to continuously calculate institute relative to the value for increasing the precoding parameters (J) Object function (u (J)) value is stated, until the difference between the object function (u (J)) two successive values is less than threshold value.
  15. 15. a kind of multi-antenna base station, including：
    The decoding apparatus that prelists (700) according to claim 13 or 14, wherein the precoder (701) be arranged to it is pre- The transmission sample sequence s (t) is encoded, based on the precoding parameters JoptIdentified value Jopt；And
    Transmitter, it is configured to the transmission sample sequence (s (t)) that the channel sends precoding.
  16. 16. a kind of pre-coding system, including：
    Precoder, it is used for the transmission sample sequence by some transmission medium for precoding；And
    Processor, it is variable for being provided to the precoder using the method according to any one of claim 1 to 12 Precoding strategy, with relative to transmission described in the pre-encoding quality of the transmission medium and contextual properties optimally precoding Sample sequence.
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