CN101621319B - Multi-cell cooperative downlink transmission user pairing method based on large-scale channel information - Google Patents

Abstract

The invention relates to a multi-cell cooperative downlink transmission user pairing method based on large-scale channel information. The method comprises the following steps: (1), users are sequenced according to the large-scale signal-interference ratio (i.e., SIR) of the users, firstly, all the users make statistics to the respective large-scale SIR and report the large-scale SIR to service base stations in cells and each base station performs sequencing to the serviced users according to the large-scale SIR values in sequence from strong to weak; and (2), the multi-cell user pairing grouping is performed according to the large-scale SIR strong and weak collocation criterion to perform numbering to the N base stations of a cooperative cluster from inside to outside according to the clockwise direction, and then the odd-even cells perform user grouping according to the large-scale SIR strong and weak collocation criterion, i.e., the NO.1 user in the odd cell and the NO.K user in the even cell are in a group, the NO.2 user in the odd cell and the NO.K-1 user in the even cell are in a group, and the NO.K user in the odd cell and the NO.1 user in the even cell are in a group; and the users in the same group accept the service of the multi-cell cooperative downlink multi-user MIMO transmission on the same time-frequency resource.

Description

A kind of multi-cell cooperative downlink transmission user matching method based on large-scale channel information

(1) technical field

A kind of multi-cell cooperative downlink transmission user matching method based on large-scale channel information of the present invention, it relates to the downlink transmission user group technology of cooperative multicast system.Belong to mobile communication, wireless communication technology field.

(2) background technology

Cooperative multipoint transmission (Coordinated Multi-Point; CoMP) many base stations, multi-user and many antenna resource be can make full use of and sub-district average throughput and cell edge throughput improved; To reach the requirement of IMT-A (International Mobile Telecommunications-Advanced, advanced international mobile communication) high spectrum utilization.

In cooperative multicast system, a plurality of sub-districts need common decision which user separately can take identical running time-frequency resource, and accept multipoint cooperative transmission service, i.e. user pairing problem jointly.

The simplest a kind of user pairing method is the random user pairing; Be that co-operating each sub-district is selected one at random at every turn and come out from own institute service-user; User with these sub-district random chooses makes up as a user then; Occupy identical running time-frequency resource, and accept collaboration services jointly.

Optimum user pairing method is at each constantly; A plurality of sub-districts are according to all users' instantaneous channel information; Travel through all possible user's combination, pick out optimum user's combination, the performance evaluation index can be system's fairness or system and data transfer rate or the like.But this method complexity is too high, needs mutual amount of information big too between the base station.If cooperate jointly in N sub-district, comprise K user in each sub-district, each sub-district is picked out 1 user separately, forms 1 user's combination that comprises N user, and then the search volume of best practice is K ^NIt is thus clear that it is quite high to seek user's combination calculation complexity of this optimum, possibly realize hardly.

Document " Marsch and G.Fettweis; " A Framework for Optimizing the DownlinkPerformance of Distributed Antenna Systems under a Constrained Backhaul "; in Proc.ofthe 13th European Wireless Conference (EW ' 07); Apr.1-4, Paris, France; 2007. " proposes a kind of user pairing method based on " degree of isolation ", utilizes large-scale channel information that the user is matched grouping.In the method, all users calculate the average signal interference ratio of receiving terminal (SIR) of oneself according to large-scale channel information.After each base station obtains all users' in this sub-district large scale SIR; The order descending according to this parameter sorts to the user, and the strongest user of large scale SIR is divided into one group in each sub-district, and SIR strong user of large scale is divided into one group;, the most weak user of large scale SIR is divided into one group.This method realizes simple, and each sub-district is as long as share K scalar value to an other N-1 sub-district, and the user grouping process need not carried out traversal search.

Our analysis shows that this user pairing scheme is compared with the random user pairing in the above-mentioned document, can make the system edges user performance impaired, reduces the fairness of system.

At present still do not have other feasible programs about the user pairing combinatorial problem in the CoMP system, more than three kinds of user pairing schemes pluses and minuses are respectively arranged, need a kind of low complex degree badly and can guarantee the user pairing group protocol of certain fairness.Proposition of the present invention is based on the support of " the great special project of new generation broadband wireless mobile communication net science and technology: IMT-Advanced cooperative multipoint transmission technical research " (20092X03003-003 of Ministry of Industry and Information).

(3) summary of the invention

1, purpose

The purpose of this invention is to provide a kind of large scale SIR that utilizes and carry out the method that user grouping improves user fairness; It forms the influence of the scheme average output signal-to-noise ratios of linear predictive coding such as (being ZF-BF) to close-to zero beam through the asymmetry of analyzing CoMP cooperation descending transmission channel; This method is compared with the method in random user pairing and the above-mentioned document; Can under the prerequisite of losing the sub-district average throughput hardly, obviously promote the cell edge spectrum efficiency.

2, technical scheme

We divide large scale SIR is stronger in arbitrary family and other sub-districts user in the multi-cell cooperating downlink transfer all can improve performance one group the time, and " strong " " weak " user pairing method can only improve performance good user in the above-mentioned document.And in the cellular system of reality, more pressing for what promote performance is to be in cell edge, user that large scale SIR is lower.Based on above analysis, we propose the pairing group technology that a kind of large scale SIR carries out " strong and weak collocation ".

A kind of multi-cell cooperative downlink transmission user matching method based on large-scale channel information of the present invention is that a kind of large scale SIR that utilizes carries out the method that user pairing improves user fairness, and these method concrete steps are following:

Step 1: according to user's large scale signal interference ratio is that SIR sorts to the user

At first, all users add up separately large scale SIR and report sub-district, place serving BS, each base station according to the large scale sir value by to weak order institute's service-user being sorted by force.

$\mathrm{SIR}={\mathrm{\&alpha;}}_{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="H2009100896314E00011.png"\; state="\{\{state\}\}">s</figure-callout>}}^2/{\mathrm{\&Sigma;}}_{i=1}^{N-1}{\mathrm{\&alpha;}}_i^2$

α wherein _sBe the large scale channel response between user and sub-district, place serving BS, α _iBe the large scale channel response between other base stations in user and the cooperation cell bunch.

Suppose to comprise in every sub-district K user, the Customs Assigned Number after the ordering is 1,2 ..., K, SIR _kBe k user's large scale SIR, SIR is then arranged ₁>=SIR ₂>=...>=SIR _K

Step 2: carry out many community user pairings by the strong and weak collocation of large scale SIR criterion and divide into groups

To N base station of cooperative cluster according to from inside to outside, clockwise direction numbers, and is as shown in Figure 1.User grouping is carried out according to the criterion of the strong and weak collocation of large scale SIR in the odd even sub-district then: No. 1 user of odd number sub-district and the K user of even number sub-district are divided into one group; No. 2 users of odd number sub-district and the K-1 user of even number sub-district are divided into one group;, No. 1 user of the K user of odd number sub-district and even number sub-district is divided into one group.

The user accepts the service of multi-cell cooperating descending multi-user MIMO transmission on same temporal frequency resource on the same group.

From to seeing the description of this method, this method complexity and required overhead are all identical with above-mentioned document, and far below the user pairing method of optimum, and transmission performance is higher than other method.

3, advantage and effect

The present invention proposes a kind of large scale SIR that utilizes and carries out the method that user pairing divides into groups to improve user fairness; It is a kind of based on large scale SIR " strong and weak collocation " many community users matching method; It is compared with the optimal user system of selection based on instantaneous channel information, and this user pairing algorithm can reduce computation complexity and required overhead greatly; It with random user pairing and above-mentioned document in method compare, this user pairing algorithm can obviously promote the cell edge spectrum efficiency, the performance comparison curves is seen Fig. 2, Fig. 3.

(4) description of drawings

Fig. 1 cell number sketch map

Fig. 2 base station end antenna number is the matching method user throughput CDF curve among matching method and the present invention in 1 o'clock random pair method, the document

Fig. 3 base station end antenna number is the matching method user throughput CDF curve among matching method and the present invention in 2 o'clock random pair methods, the document

Multi-cell cooperative downlink transmission user pairing sketch map among Fig. 4 the present invention

Symbol description is following among the figure:

CDF curve representation cumulative probability function curve; User Throughput representes user throughput;

1-7 representes the sub-district sequence number; A representes random user matching method user throughput CDF curve; B representes the matching method user throughput CDF curve among the present invention; C representes matching method user throughput CDF curve in the document.Represent customer location with mobile phone end among Fig. 4, identical mobile phone end representes that the user is assigned as same group.

(5) specific embodiments

The present invention proposes a kind of large scale SIR that utilizes and carries out the method that user pairing divides into groups to improve user fairness; The design philosophy of this method is that strong user of large scale SIR in the cooperation cell and more weak user are divided into one group, and promptly the mode of " strong and weak collocation " is with user pairing.This user pairing mode can promote the performance that is in cell edge, user that large scale SIR is lower.

For making the object of the invention, technical scheme and advantage clearer, the present invention is done to describe in detail further below in conjunction with accompanying drawing and practical implementation instance.

Suppose that the cooperation cell number is 7, cell number is by shown in Figure 1, and each sub-district comprises 10 users, and then multi-user's group protocol implementation step of these 7 cell cooperatives is following:

Step 1: SIR sorts to the user according to user's large scale

70 user's statistics large scale SIR separately of in the cooperation cell all $(\mathrm{SIR}={\mathrm{\&alpha;}}_s^2/{\mathrm{\&Sigma;}}_{i=1}^{N-1}{\mathrm{\&alpha;}}_i^2)$ Report and belong to the sub-district serving BS separately; Each base station according to the large scale sir value by to weak order user in the sub-district being sorted by force.If the Customs Assigned Number after the ordering is 1,2 ..., 10, SIR _kBe k user's large scale SIR, SIR is then arranged ₁>=SIR ₂>=...>=SIR ₁₀

Step 2: carry out many community user pairings by the strong and weak collocation of large scale SIR criterion and divide into groups

7 sub-districts of cooperation constitute a cooperative cluster, and cell number is as shown in Figure 1 in bunch.User grouping is carried out according to the strong and weak collocation of large scale criterion in the odd even sub-district: 1, No. 10 users of 3,5,7 sub-districts No. 1 same 2,4,6 sub-district of user are divided into one group; 1, No. 9 users of 3,5,7 sub-districts No. 2 same 2,4,6 sub-districts of user are divided into one group; 1,3,5,7 sub-districts No. 3 users are divided into one group with No. 8 users of 2,4,6 sub-districts, by that analogy, are divided into one group, the grouping process end up to No. 10 users of 1,3,5,7 sub-districts and 2,4,6 No. 1 user.

User on the same group accepts multi-cell cooperating descending multi-user MIMO transmission service on identical temporal frequency resource.

Facts have proved that the present invention is a kind of low complex degree and the user pairing scheme that can guarantee certain fairness.

Claims (1)

1. multi-cell cooperative downlink transmission user matching method based on large-scale channel information, it is characterized in that: these method concrete steps are following:

Step 1: according to user's large scale signal interference ratio is that SIR sorts to the user

At first, all users add up separately large scale SIR and report sub-district, place serving BS, each base station according to the large scale sir value by to weak order institute's service-user being sorted by force;

$\mathrm{SIR}={\mathrm{\&alpha;}}_s^2/{\mathrm{\&Sigma;}}_{i=1}^{N-1}{\mathrm{\&alpha;}}_i^2$

α wherein _sBe the large scale channel response between user and sub-district, place serving BS, α _iBe the large scale channel response between other base stations in user and the cooperation cell bunch;

Suppose to comprise in every sub-district K user, the Customs Assigned Number after the ordering is 1,2 ..., K, SIR _kBe k user's large scale SIR, SIR is then arranged ₁>=SIR ₂>=...>=SIR _K

Step 2: carry out many community user pairings by the strong and weak collocation of large scale SIR criterion and divide into groups

To N base station of cooperative cluster according to from inside to outside, clockwise direction numbers; User grouping is carried out according to the criterion of the strong and weak collocation of large scale SIR in the odd even sub-district then: No. 1 user of odd number sub-district and the K user of even number sub-district are divided into one group; No. 2 users of odd number sub-district and the K-1 user of even number sub-district are divided into one group;, No. 1 user of the K user of odd number sub-district and even number sub-district is divided into one group; The user accepts the service of multi-cell cooperating descending multi-user multiple-input, multiple-output MIMO (Multiple-Input Multiple-Output) transmission on same temporal frequency resource on the same group.

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