CN102036396B - Downlink multi-antenna cooperation multipoint transmission-oriented feedback codebook bit allocation method - Google Patents

Abstract

The invention relates to a downlink multi-antenna cooperation multipoint transmission-oriented feedback codebook bit allocation method and belongs to the technical field of wireless communication. The method comprises the following steps that: users measure average signal energy of a plurality of base stations to the users and feed the average signal energy back to a serving base station by an uplink channel; the serving base station transmits the information to a central processing unit; the central processing unit calculates a codebook bit number for each user by utilizing the positions of the users and related information according to scheduling results of a plurality of users and the communication quality requirements and transmits calculation results to the corresponding users; the users search codebooks according to the bit numbers and quantize the channel by using the codebooks; the users transmit codeword indexes which are obtained by quantization to the base stations; and the base stations transmit the codeword indexes to the central processing unit and generate precoded codes according to received code words. By the method, the position information of the users can be effectively utilized to calculate the required minimum feedback bit numbers which meet the communication quantity requirements of the users so as to meet the performance of the users and reduce the feedback overhead required by a system.

Description

Feedback code book Bit distribution method towards descending multi-antenna cooperative multicast communication

Technical field

The present invention relates to a kind of feedback code book Bit distribution method towards descending multi-antenna cooperative multicast communication, when relating in particular to user in a kind of multi-BS (base station) multi-user Limited Feedback system local channel and cross-channel being fed back, the method for Bit Allocation in Discrete, belong to wireless communication technology field.

Background technology

Cooperative multipoint transmission (Coordinated Multi-Point, CoMP) can effectively improve spectrum efficiency, suppresses minizone, inter-sector interference, is one of important technology of Long Term Evolution plan (LTE-A).In the CoMP cooperative processing system, the base station can obtains the essential condition that channel information (CSI) becomes performance CoMP system advantage.Frequency Division Duplexing (FDD) (FDD) down collaboration transmission system need to be by Bandwidth-Constrained the up channel feedback channel information, so overhead can become serious problems, even can offset the system performance gain that CoMP brings.Therefore, to satisfy the feedback quantity that reduces as far as possible Limited Feedback under the prerequisite of QoS of customer most important.

Compare with its traditional non-cooperative transmission system, the CoMP system has the Some features of self, such as channel asymmetry, cooperative base station number are dynamic or semi-static variation etc.This causes for global channel combined optimization design codebooks and selects code word unrealistic.Based on the feedback technique of single channel (per-cell) code book due to its flexibility and good backwards compatibility more feasible in real system.

Per-cell code book feedback technique refers to that independently per-cell code book is used in each residential quarter in the CoMP system, and the user quantizes respectively the scheme fed back to the channel of each residential quarter.

Consider the CoMP system of N base station collaboration, there is M root antenna each base station, user side configuration single antenna, a plurality of users of CoMP system service.K user's descending global channel (global channel) can be made of the channel of each cooperative base station to this user:

$g_k=\left[\begin{array}{ccccc}{\mathrm{\α}}_{k,1}{h}_{k,1},& {\mathrm{\α}}_{k,2}{h}_{k,2},& ...& {\mathrm{\α}}_{k,N_c}& h_{k,N}\end{array}\right]$

H wherein _{K, i}Be i base station to k serviced user's per-cell small scale channel vector, its each element is for statistics independent same distribution and average are zero, variance is 1 multiple Gaussian random variable, a _{K, i}Be the corresponding path loss factor, i=1 ..., N.

Suppose that user k is to the channel h of base station i _{K, i}The code word that quantizes to obtain feeding back is

The base station that participates in cooperation will obtain codeword information and feed back to respectively center processor (CU), the global channel after CU finally obtains to quantize:

${\hat{g}}_k=\left[\begin{array}{cccc}{\mathrm{\α}}_{k,1}{\hat{h}}_{k,1},& {\mathrm{\α}}_{k,2}{\hat{h}}_{k,2},& ...& {\mathrm{\α}}_{k,N}{\hat{h}}_{k,N}\end{array}\right]$

Can adopt the ZF precoding technique to eliminate inter-user interference and carry out the space division multiplexing transmission.All users' that obtain according to CU compound channel

With the ZF matrix

K row carry out obtaining v after normalization _k=V (:, k)/|| V (:, k) || as k user's precoding vector.

The average quantization precision of considering the channel direction of per-cell channel is

(channel direction wherein

), and establish k user B is used in b base station _{K, b}The code book feedback of bit, the upper bound of average quantization precision is

Present existing Bit Allocation in Discrete scheme just simple consideration waits the distribution of bit to subscriber's local channel and cross-channel, do not take full advantage of the asymmetric property of channel, if bit number is smaller, can cause the CoMP systematic function not even as the performance of non-CoMP system.

Summary of the invention

The objective of the invention is to propose a kind of feedback code book Bit distribution method towards descending multi-antenna cooperative multicast communication, take full advantage of the asymmetric property of channel, when having designed the multi-user Cooperation transmission, the user carries out the method for optimum Bit Allocation in Discrete according to self large scale information and pairing user's large scale information to local channel and cross-channel, reduces the needed feedback overhead of system when satisfying the user performance demand.

The feedback code book Bit distribution method towards descending multi-antenna multi-base station cooperation transmission that the present invention proposes comprises with next step:

(1) establish cooperative transmission system and be comprised of N base station, M antenna of each base station configuration connects by center processing unit between each base station; Dispatch the multi-user in cooperative transmission system the base station, selects K user wherein to serve simultaneously;

(2) notice K user being scheduled out in a plurality of base stations measures in N base station and the long-time statistical average signal energy of channel between the user

J=1 ... K, b=1 ..., N; J user by uplink feedback channel with above-mentioned long-time statistical average signal energy

Feed back to b base station in N base station, b base station is with the long-time statistical average signal energy that receives

Be transferred to center processing unit;

(3) center processing unit requires γ according to the communication quality of k user's setting of above-mentioned selection _k, pass through following formula:

Calculate the bit number B that distributes between k user and b base station _{K, b}, wherein

λ satisfies

(0, x) computing repeats this step to expression max, obtains distributing to the bit number between all selection users and each base station;

(4) center processing unit will be distributed to all and select users and bit number between each base station to be transferred to corresponding base station in cooperative transmission system, and by corresponding base station, the bit number of distribution will be transferred to corresponding user;

(5) channel vector of establishing between k user and b base station is h _{K, b}, k the bit number B that the user notifies according to b base station _{K, b}Search from this user's code library and bit number B _{K, b}Corresponding code book C _{K, b}, C _{K, b}Comprise

Individual code word, k user according to

Obtain code word c _{K, b}, and to b this code word of base station feedback, repeat this step, all base stations obtain the code word of relative users;

(6) each base station in cooperative transmission system is respectively with the feedback code c that receives _{K, b}Be transferred to center processing unit;

(7) center processing unit finds corresponding code word according to the feedback code index of all base stations that receive, and reconstruct obtains each user's global channel, utilizes all users' global channel, generates the precoding of cooperative transmission system.

The feedback code book Bit distribution method towards descending multi-antenna cooperative multicast communication that the present invention proposes, its advantage is:

In the present invention, the user measures a plurality of base stations to self long-time statistical average signal energy, and by up channel, this signal energy is fed back to serving BS, serving BS with this communication to center processing unit.Center processing unit is according to scheduling result, and the user's who dispatches out communication quality requirement, quantizes the needed bit number of each BTS channel for each user calculates this user; Then the bit number that calculates is transferred to relative users, the user searches corresponding code book according to the bit number of base station notice, and utilizes corresponding code book that corresponding per-cell channel is quantized; End user is transferred to the base station with the codewords indexes that represents respectively each BTS channel that quantizes to obtain, base-station transmission is to center processing unit, center processing unit finds corresponding code word according to the codewords indexes of receiving, reconstruct obtains each user's global channel, utilizes all users' global channel to generate the multi-base station cooperative transfer pre-coding.The inventive method can take full advantage of user's large scale information, with and the pairing user large scale information, calculate the user to the Optimal Feedback code book Bit Allocation in Discrete of local channel and cross-channel, thereby obtain minimum feedback bits total amount under the prerequisite of the communication quality demand that guarantees the user, reduce the needed feedback overhead of system when satisfying the user performance demand.

Description of drawings

Fig. 1 is the FB(flow block) of the inventive method.

Fig. 2 is the system block diagram of cooperative transmission system.

Embodiment

The feedback code book Bit distribution method towards descending multi-antenna multi-base station cooperation transmission that the present invention proposes, its FB(flow block) comprises as shown in Figure 1 with next step:

(1) establish cooperative transmission system and be comprised of N base station, M antenna of each base station configuration connects by center processing unit between each base station; Dispatch the multi-user in cooperative transmission system the base station, selects K user wherein to serve simultaneously, and the system block diagram of cooperative transmission system as shown in Figure 2.

(2) notice K user being scheduled out in a plurality of base stations measures in N base station and the long-time statistical average signal energy of channel between the user

J=1 ... K, b=1 ..., N; J user by uplink feedback channel with above-mentioned long-time statistical average signal energy

Feed back to b base station in N base station, b base station is with the long-time statistical average signal energy that receives

Be transferred to center processing unit.

(3) center processing unit requires γ according to the communication quality of k user's setting of above-mentioned selection _k, pass through following formula: Calculate the bit number B that distributes between k user and b base station _{K, b}, wherein

λ satisfies

(0, x) computing repeats this step to expression max, obtains distributing to the bit number between all selection users and each base station.

(4) center processing unit will be distributed to all and select users and bit number between each base station to be transferred to corresponding base station in cooperative transmission system, and by corresponding base station, the bit number of distribution will be transferred to corresponding user;

(5) channel vector of establishing between k user and b base station is h _{K, b}, k the bit number B that the user notifies according to b base station _{K, b}Search from this user's code library and bit number B _{K, b}Corresponding code book C _{K, b}, C _{K, b}Comprise

Individual code word, k user according to

Obtain code word c _{K, b}, and to b this code word of base station feedback, repeat this step, all base stations obtain the code word of relative users.

(6) each base station in cooperative transmission system is respectively with the feedback code c that receives _{K, b}Be transferred to center processing unit.

(7) center processing unit finds corresponding code word according to the feedback code index of all base stations that receive, and reconstruct obtains each user's global channel, utilizes all users' global channel, generates the precoding of cooperative transmission system.

Describe content of the present invention in detail below in conjunction with accompanying drawing:

(1) establish cooperative transmission system and be comprised of N base station, M antenna of each base station configuration connects by center processing unit between each base station; The base station utilizes traditional user scheduling method, such as proportional fair dispatching method, the multi-user in cooperative transmission system is dispatched, and selects K user wherein to serve simultaneously.

(2) notice K user being scheduled out in a plurality of base stations measures in N base station and the long-time statistical average signal energy of channel between the user

J=1 ... K, b=1 ..., N; J user by uplink feedback channel with above-mentioned long-time statistical average signal energy Feed back to b base station in N base station, b base station is with the long-time statistical average signal energy that receives Be transferred to center processing unit;

(3) center processing unit requires γ according to the communication quality of k user's setting of above-mentioned selection _k, pass through following formula: Calculate the bit number B that distributes between k user and b base station _{K, b}, wherein

λ satisfies

(0, x) computing repeats this step to expression max, obtains distributing to the bit number between all selection users and each base station;

(4) center processing unit will be distributed to all and select users and bit number between each base station to be transferred to corresponding base station in cooperative transmission system, and notify corresponding user by corresponding base station with the bit number of distribution;

(5) channel vector of establishing between k user and b base station is h _{K, b}, k the bit number B that the user notifies according to b base station _{K, b}Search from this user's code library and bit number B _{K, b}Corresponding code book C _{K, b}, C _{K, b}Comprise

Individual code word, k user according to Obtain code word c _{K, b}, and to b this code word of base station feedback, repeat this step, all base stations obtain the code word of relative users;

(6) each base station in cooperative transmission system is respectively with the feedback code c that receives _{K, b}Be transferred to center processing unit;

(7) center processing unit finds corresponding code word according to the feedback code index of all base stations that receive, and reconstruct obtains each user's global channel, utilizes all users' global channel, generates the precoding of cooperative transmission system.

Claims (1)

1. feedback code book Bit distribution method towards descending multi-antenna multi-base station cooperation transmission is characterized in that the method comprises with next step:

(1) establish cooperative transmission system and be comprised of N base station, M antenna of each base station configuration connects by center processing unit between each base station; Dispatch the multi-user in cooperative transmission system the base station, selects K user wherein to serve simultaneously;

(2) notice K user being scheduled out in a plurality of base stations measures in N base station and the long-time statistical average signal energy of channel between the user

J=1 ... K, b=1 ..., N; J user by uplink feedback channel with above-mentioned long-time statistical average signal energy

Feed back to b base station in N base station, b base station is with the long-time statistical average signal energy that receives Be transferred to center processing unit;

(3) center processing unit requires γ according to the communication quality of k user's setting of above-mentioned selection _k, pass through following formula: $B_{k,b}=(M-1){({\log }_2\mathrm{\λ}+{\log }_2\left({\mathrm{\α}}_{k,b}^4(1+{\mathrm{\β}}_{k,b}{v}_{k,b})\right))}^{+},$ Calculate the bit number B that distributes between k user and b base station _{K, b}, wherein ${\mathrm{\β}}_{k,b}^2={\mathrm{\Σ}}_{j=1,j\≠k}^N{\mathrm{\α}}_{j,b}^2\left({\mathrm{\Σ}}_{n=1}^N{\mathrm{\α}}_{j,n}^2\right),$ $v_{k,b}={\mathrm{N\γ}}_k\left({\mathrm{\Σ}}_{n=1}^N{\mathrm{\α}}_{k,n}^2\right)/\left({\mathrm{\α}}_{k,b}^2(N-1)\right),$ $T_k={\mathrm{\Σ}}_{n=1}^N{\mathrm{\α}}_{k,n}^4,$ λ satisfies ${\mathrm{\Σ}}_{n=1}^N(1+{\mathrm{\β}}_{k,n}{v}_{k,n}){\mathrm{\α}}_{k,n}^4{2}^{-B_{k,n}/(M-1)}=T_k,$ (x) ⁺Expression max (0, x) computing repeats this step, obtains distributing to the bit number between all selection users and each base station, and wherein n represents n base station, n=1 ... N;

(4) center processing unit will be distributed to all and select users and bit number between each base station to be transferred to corresponding base station in cooperative transmission system, and by corresponding base station, the bit number of distribution will be transferred to corresponding user;

(5) channel vector of establishing between k user and b base station is h _{K, b}, k the bit number B that the user notifies according to b base station _{K, b}Search from this user's code library and bit number B _{K, b}Corresponding code book C _{K, b}, C _{K, b}Comprise

Individual code word, k user according to

Obtain code word c _{K, b}, and to b this codewords indexes of base station feedback, repeat this step, all base stations obtain the codewords indexes of relative users;

(6) each base station in cooperative transmission system is respectively with the feedback code c that receives _{K, b}Index is transferred to center processing unit;

(7) center processing unit finds corresponding code word according to the feedback code index of all base stations that receive, and reconstruct obtains each user's global channel, utilizes all users' global channel, generates the precoding of cooperative transmission system.

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