CN103401659A - Uniflow beam forming method based on codebook in TD-LTE (Time Division Long Term Evolution) system - Google Patents

Abstract

Codebook-based single stream beam form-endowing method in a kind of TD-LTE system, comprising: antenna calibration compensation is carried out to 8 antenna of TD-LTE system; First phase normalization is carried out to 8 antenna of system, by new channel estimation value

Channel estimation correction value H (1) (kaRx, n) after calculating phase normalization; Judge the granularity of beam shape-endowing weight value,If weight granularity is m radio bearer block,If m amp; amp; gt; 1, then first the channel estimation value of m radio bearer block is averaging,Then it is transferred to the 4th step,If m=1,Directly it is transferred to the 4th step; The search of wave beam forming code book weight is carried out,According to related weight searching algorithm,Wave beam forming code book weight is searched for by channel estimation value H (1) (kaRx, n),Wave beam forming code book serial number is obtained,Judge whether to traverse all radio bearer blocks,If so,Then this figuration terminates,If not,Then go to third step. This approach reduce the complexities of beamforming algorithm, reduce system cost of implementation.

Description

In a kind of TD-LTE system based on the single current beam form-endowing method of code book

Technical field

The present invention relates to multi-antenna technology in the TD-LTE wireless communication system (MIMO) field, be specifically related in a kind of TD-LTE system the single current beam form-endowing method based on code book.

Background technology

LTE is subject to the favor of Mobile Communication Industry always.Along with the development of LTE technology, increasing world-leading operator faces the future LTE one after another as network evolution direction, equipment manufacturers have also strengthened the input in the LTE field one after another, thereby have promoted constantly advancing of LTE.With the 3G (Third Generation) Moblie technology, compare, LTE has following technical characterictic: (1) reduces every bit cost, improves the uplink and downlink communication data rate; (2) spectrum efficiency improves, and uses flexibly existing and new frequency range; (3) guarantee service quality, the providing capability of activating business, experience with lower cost, better user the more business that provides; (4) reduce the wireless network time delay, simplify framework, open interface; (5) increase the cell edge bit rate, in the situation that keep the constant increase of present base station location cell edge bit rate etc.

MIMO technique refers to and utilizes multi-emitting, multiple receive antenna to carry out the technology of space diversity.What it adopted is the many antennas of discrete, can effectively communication link be resolved into to many parallel subchannels, thereby greatly improve capacity.At the down link of TD-LTE, the send mode of many antennas mainly comprises transmit diversity, wave beam forming, when empty and the technology such as coding and multi-user's multiple-input and multiple-output.The application scenarios that the support of TD-LTE system is abundant, its transmission mode that has defined 9 kinds of downlink business is to guarantee in various environment the technical scheme of can selectivity optimizing.Wherein, emission mode 7, emission mode 8 and emission mode 9 are beam-forming mode.

Wave beam forming is a kind of technology of Signal Pretreatment based on aerial array, utilize the strong correlation of space channel and the principle of interference of ripple to produce the radiation diagram that certain orientation is arranged, make the adaptive sensing of the main lobe user of antenna pattern, thereby improve signal to noise ratio, obtain obvious array gain.The purpose of wave beam forming is in order to enlarge signal cover, to improve the edge throughput and suppress and disturb.How to produce effectively efficiently the variation that beam shape-endowing weight value carrys out match channels, thereby improve the throughput of system, become the sole criterion of weighing beamforming algorithm.

In LTE R8, support the single current wave beam forming technology based on dedicated pilot, according to agreement, in transmitting procedure, user terminal need to be estimated the equivalent channel after wave beam forming, going forward side by side relevant the detection by the measurement to dedicated pilot.In order to estimate to transmit the channel that experiences after wave beam forming, base station must send a wave beam forming reference signal with Simultaneous Transmission of Data, this reference signal is user's special use, corresponding to the transmission of user's DRS (Dedicated Reference Signal), is called the transmission of using antenna port 5.The wave beam forming technology can effectively improve the service quality of Cell Edge User, the coupling of figuration vector and current channel becomes the key factor that affects the figuration effect, because wireless channel environment often changes rapidly, therefore realize that the system descending wave beam forming not only will consider the figuration effect, but also will consider the processing speed of figuration.

TD-LTE system descending wave beam forming mainly adopts based on the method computation complexity of singular value decomposition higher at present.

Summary of the invention

Technical problem to be solved by this invention is to overcome the shortcoming of prior art, provides that a kind of method is simple, cost is low, is easy in TD-LTE system that software and hardware implements the single current beam form-endowing method based on code book.

Solving the problems of the technologies described above the technical scheme that adopts comprises the steps:

Design TD-LTE8 antenna beam figuration code book:

$v_i={\left[\begin{array}{cccc}1& {\mathrm{<figure-callout\; id="2"\; label="e\; j"\; filenames="HDA00003533529100012.png"\; state="\{\{state\}\}">e</figure-callout>}}^j& e^{j4\mathrm{\&pi;}*2*i/32}& {\mathrm{<figure-callout\; id="6"\; label="e\; j"\; filenames="HDA00003533529100012.png"\; state="\{\{state\}\}">e</figure-callout>}}^j\end{array}\right]}^T$

$v_j={\left[\begin{array}{cccc}1& {\mathrm{<figure-callout\; id="2"\; label="e\; j"\; filenames="HDA00003533529100012.png"\; state="\{\{state\}\}">e</figure-callout>}}^j& e^{j4\mathrm{\&pi;}*2*j/32}& {\mathrm{<figure-callout\; id="6"\; label="e\; j"\; filenames="HDA00003533529100012.png"\; state="\{\{state\}\}">e</figure-callout>}}^j\end{array}\right]}^T$

Wherein, i is 0,1 ..., 15; J is 0,1 ..., 15;

16 * 16 * 16=4096 altogether of codebook selecting.

One, TD-LTE system 8 antennas are carried out to the antenna calibration compensation, according to the original channel estimated value

With up correction weights, calculate the rear channel estimating of antenna calibration compensation

Wherein n is radio bearer piece number index, ka _RxFor antenna index, u is the user terminal index.

Two, system 8 antennas are carried out to first phase normalization, by new channel estimation value

Channel estimating correction value H after the calculating phase normalization ₍₁₎(ka _Rx, n).

Three, the granularity of judgement beam shape-endowing weight value, establishing the weights granularity is m radio bearer piece, if m > 1, first the channel estimation value of m radio bearer piece is averaging, then changes step 4 over to; M is 1, changes step 4 over to.

Four, carry out the search of wave beam forming code book weights, according to relevant weights searching algorithm (concrete implementation step describes in detail), by channel estimation value H ₍₁₎(ka _Rx, n) search wave beam forming code book weights, obtain wave beam forming code book sequence number, judges whether to travel through all radio bearer pieces, and if so, this figuration finishes, and if not, goes to step three.

The present invention adopts the method for precoding, and default wave beam forming code book in system is realized efficient figuration fast by the search weighted vector.The present invention proposes a kind of beam form-endowing method based on codebook search, by building the shape-endowing weight value code book, according to channel estimating information, code presupposition is searched for, and realizes the single current wave beam forming.After using the present invention, the complexity of single current wave beam forming reduces greatly, and the figuration effect approaches the related algorithm based on singular value decomposition.In the wave beam forming process, without the computer memory correlation matrix, and computational process greatly reduces the amount of calculation of single current wave beam forming without singular value decomposition, compared to traditional singular value decomposition method, is easier to software and hardware and realizes.

The accompanying drawing explanation

Fig. 1 is the wave beam forming overall process flow figure of TD-LTE system based on code book.

Fig. 2 is base station and user terminal antenna set-up mode figure.

Embodiment

The present invention is described in more detail below in conjunction with drawings and Examples, but the invention is not restricted to these embodiment.

Embodiment 1

Single current beam form-endowing method step based on code book in the present embodiment TD-LTE system is as follows:

Base station and user terminal antenna setting are seen accompanying drawing 2.

The first step: the TD-LTE8 antenna is carried out to antenna calibration compensation 11, according to the original channel estimated value

With up correction weights

Calculate the channel estimation value after new antenna calibration compensates Be calculated as follows;

${\stackrel{\&OverBar;}{H}}_1^{\left(u\right)}(n,{\mathrm{ka}}_{\mathrm{Rx}})=(H_1^{\left(u\right)}(n,{\mathrm{ka}}_{\mathrm{Rx}})\&times;{\mathrm{\&omega;}}_{\mathrm{UL}}^{\mathrm{AC}}(n,{\mathrm{ka}}_{\mathrm{Rx}}))$

Wherein n is radio bearer piece number index,

For antenna index, u is the user terminal index.

Annotate: up correction weights Computational methods as follows, after the average H that obtains each subcarrier on each passage, also just obtained the magnitude-phase characteristics of each subcarrier, take certain passage as benchmark, with online bearing calibration, calculate the width phase inconsistency of each passage with respect to reference channel, obtain the penalty coefficient of each antenna channels, namely proofread and correct weights;

Second step: system 8 antennas are carried out to first phase normalization, by new channel estimation value

Channel estimating correction value H after the calculating phase normalization ₍₁₎(ka _Rx, n), ka _RxFor antenna index, by following formula, calculate;

Loop=1:M, M are radio bearer piece sum, and in the present embodiment, getting M is 8.

1. ask the phase theta of every first antenna of radio bearer piece

$\mathrm{\&theta;}=\arctan \left(\frac{\mathrm{imag}\left(\stackrel{\&OverBar;}{H_1}(1,\mathrm{Loop})\right)}{\mathrm{real}\left(\stackrel{\&OverBar;}{H_1}(1,\mathrm{Loop})\right)}\right)$

2. every radio bearer piece carries out normalization according to antenna 1 phase place

$H_{\left(1\right)}({\mathrm{ka}}_{\mathrm{Rx}},\mathrm{Loop})=\frac{\stackrel{\&OverBar;}{H_1}({\mathrm{ka}}_{\mathrm{Rx}},\mathrm{Loop})}{\cos \mathrm{\&theta;}+j\sin \mathrm{\&theta;}}$

Carry out 8 circulations.

The 3rd step: the granularity 12 of judgement shape-endowing weight value, establishing the weights granularity is m radio bearer piece, if m > 1, first the channel estimation value of m radio bearer piece is averaging, then change the 4th step over to, m radio bearer piece channel estimation value is averaging 13, and computing formula is summarized as follows; If m=1, directly change the 4th step over to;

Loop=1:M, M are radio bearer piece sum, and in the present embodiment, getting M is 8.

${\stackrel{=}{H}}_{\left(1\right)}({\mathrm{Ka}}_{\mathrm{Tx}},\mathrm{Loop})=\frac{\underset{\mathrm{ii}=1}{\overset{m}{\mathrm{\&Sigma;}}}{H}_{\left(1\right)}({\mathrm{Ka}}_{\mathrm{Tx}},\mathrm{ii})}{m}$

The 4th step: wave beam forming code book weights search 14, v _mFor code book 1(m=0-15),

For code book 2(n=0-15); Finally try to achieve wave beam forming code book sequence number 15PMI corresponding on the radio bearer piece ₁(I, J, K), concrete computational process is as follows.

(1) when weights granularity m be 1 radio bearer piece

Loop=1:M, M are radio bearer piece sum, and in the present embodiment, getting M is 8;

In order to simplify search volume, at i, j, search in 3 16 code books of k. and wave beam forming code book weights search for 17 respectively, meet the wave beam forming code book sequence number i of following formula, j, k is calculated as follows:

$G11\left(i\right)=v_i^T\&times;H_{\left(1\right)}(\mathrm{indexl},\mathrm{Loop})$

Wherein, index1 is 4 antennas that port0 is corresponding, preserves, then presses the following formula computing;

${\mathrm{<figure-callout\; id="11"\; label="G"\; filenames="HDA00003533529100011.png"\; state="\{\{state\}\}">G</figure-callout>}11}_{\max }=\underset{i}{\arg }\left(\max \right\{{\left|\mathrm{Gll}\left(i\right)\right|}^2\left\}\right)$

Search for 16 times, obtain I ₁

$G12\left(j\right)=v_j^T\&times;H_{\left(1\right)}(\mathrm{<figure-callout\; id="2"\; label="index"\; filenames="HDA00003533529100012.png"\; state="\{\{state\}\}">index</figure-callout>}2,\mathrm{Loop})$

Wherein, index2 is 4 antennas that port1 is corresponding, preserves, then presses the following formula computing;

${\mathrm{<figure-callout\; id="12"\; label="G"\; filenames="HDA00003533529100011.png"\; state="\{\{state\}\}">G</figure-callout>}12}_{\max }=\underset{j}{\arg }\left(\max \right\{{\left|G12\left(j\right)\right|}^2\left\}\right)$

Search for 16 times, obtain J ₁

${G1}_{\max }=\underset{k}{\arg }\left(\max \right\{{\left|G1\left(k\right)\right|}^2\left\}\right)$

Search for 16 times, obtain K ₁

Obtain TD-LTE8 antenna beam figuration code book sequence number 18, PMI _W1(I ₁, J ₁, K ₁)

Until complete all the radio bearer pieces 19 of searching loop, wave beam forming finishes 20.

(2) weights granularity m > 1 radio bearer piece

Loop=1:

M is radio bearer piece sum, M value 8 in the present embodiment, and m is the shape-endowing weight value granularity, the m value is 2.

W1 search wave beam forming code book process is with m=1 radio bearer piece, and what the channel estimating of using during search was got is mean value

Carry out 4 circulations.Until complete all the radio bearer pieces 16 of searching loop, wave beam forming finishes 20.

Claims (1)

1. In a TD-LTE system based on the single current beam form-endowing method of code book, it is characterized in that the method is comprised of following steps:

   TD-LTE8 antenna beam figuration code book is:

   

   

   $v_i={\left[\begin{array}{cccc}1& e^{j2\mathrm{\&pi;}*2*i/32}& e^{j4\mathrm{\&pi;}*2*i/32}& e^{j6\mathrm{\&pi;}*2*i/32}\end{array}\right]}^T$

   $v_j={\left[\begin{array}{cccc}1& e^{j2\mathrm{\&pi;}*2*j/32}& e^{j4\mathrm{\&pi;}*2*j/32}& e^{j6\mathrm{\&pi;}*2*j/32}\end{array}\right]}^T$

   Wherein, i is 0,1 ..., 15; J is 0,1 ..., 15,16 * 16 * 16 altogether of codebook selecting;

   One, TD-LTE system 8 antennas are carried out to the antenna calibration compensation, according to the original channel estimated value

   

   With up correction weights, calculate the rear channel estimating of antenna calibration compensation

   

   Wherein n is radio bearer piece number index, ka _RxFor antenna index, u is the user terminal index;

   Two, system 8 antennas are carried out to first phase normalization, by new channel estimation value

   

   Channel estimating correction value H after the calculating phase normalization ₍₁₎(ka _Rx, n);

   Three, the granularity of judgement beam shape-endowing weight value, establishing the weights granularity is m radio bearer piece, if m > 1, first the channel estimation value of m radio bearer piece is averaging, then changes step 4 over to; M is 1, changes step 4 over to;

   Four, carry out the search of wave beam forming code book weights, according to relevant weights searching algorithm, by channel estimation value H ₍₁₎(ka _Rx, n) search wave beam forming code book weights, obtain wave beam forming code book sequence number, judges whether to travel through all radio bearer pieces, and if so, this figuration finishes, and if not, goes to step three.

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