CN102088300A

CN102088300A - Angle-of-arrival (AOA) estimation-based CoMP user grouping method

Info

Publication number: CN102088300A
Application number: CN2009102165493A
Authority: CN
Inventors: 魏宁; 李沁沛
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2009-12-04
Filing date: 2009-12-04
Publication date: 2011-06-08

Abstract

The invention provides a simple angle-of-arrival (AOA) estimation-based CoMP user grouping method and belongs to the technical field of wireless communication. User equipment (UE) is grouped according to wave beam areas of different sites corresponding to the UE so as to fulfill the aims of saving resources and expanding volume. By the simple angle-of-arrival (AOA) estimation-based CoMP user grouping method, the aims of saving resources and expanding volume are fulfilled by grouping the UE according to the wave beam areas of different sites corresponding to the UE. In time division duplex (TDD), when channel change is relatively slow, estimation on an uplink AOA can be used as a dead on arrival (DOA) of downlink transmission (in a frequency division duplex (FDD), the DOA needs to be determined through feedback). Because long term evolution (LTE) + may support more site antennae, a more accurate AOA estimation value can be acquired and a transmit beam with better directional characteristic can be formed at the same time.

Description

CoMP user packet method based on the AOA estimation

Technical field

This patent belongs to wireless communication technology field, particularly the user packet method of CoMP

Background technology

In LTE ^[1], because the UE of cell edge is in interference-limited environment, (Inter-Cell Interference ICI), can reduce this regional average throughput so generally can to adopt fractional frequency reuse modes such as (FFR) to suppress presence of intercell interference.IMT-A covers for cell edge and the requirement of capacity in order to satisfy, and must adopt technology such as coordinate multipoint (CoMP), network MIMO ^{[2] [3]}Beam shaping method based on airspace filter can reduce inter-user interference by narrower launching beam, thus the elevator system performance.In TDD, when channel variation is slow, the DOA that can utilize estimation to up AOA to can be used as downlink uses (FDD then needs to decide DOA by feedback), because LTE+ may support more site antenna number, so can obtain AOA estimated value more accurately, can form the better launching beam of directional property simultaneously.In CoMP, because the participation of many site, each site all can form different wave beams and cover pattern, has so just increased the complexity of beam selection and utilization in addition.

Summary of the invention

This patent has proposed a kind of simply based on the CoMP user packet method of AOA, according to the wave beam zone of the different site of UE correspondence, UE is divided into groups, and to reach the saving resource, promotes the purpose of capacity.

As DL CoMP as shown in Figure 1, have 3 site and participate in the cooperation downlink transfer.Each site can form 3 wave beams.Carry out according to AOA under the situation of user's running time-frequency resource grouping planning not considering, zone A, the user of B must adopt the orthogonal time frequency resources piece to carry out the DL transfer of data, but after consideration is carried out user grouping according to AOA, obvious A, two groups of users in B zone can adopt identical time to carry out the DL transfer of data, so just can save transfer resource, improve power system capacity.

If carry out above-mentioned resource reuse, just must the user be divided into groups according to the wave beam zone situation of residing each site of user.Describe with simple example below, suppose to have 6 users and need transmit data, based on diagonalization precoding at the Channel Transmission matrix H, consider the accuracy of H feedback and the problem of robustness, suppose to realize at most that 4 users' is multiplexing, suppose that each user needs n RB transmission data, then common multithread Beamforming needs 2n RB transmission data.

Estimate and X2interface mutual that by up AOA each Site can obtain the corresponding wave beam of 6 users in 3 Site.For any one geographical distribution of 6 users, can obtain a user profile as shown in Figure 2, the scheme that we propose just is based on user profile the user is divided into groups.If distribute as shown in Figure 2, obviously, we can be divided into one group with user " 1,2,3,4 ", and (used resource is: Site1-Beam1,2; Site2-Beam1,3; Site3-Beam3), user " 5,6 " is divided into one group (used resource is: Site1-Beam3; Site2-Beam2; Site3-Beam1,2).Two groups are adopted identical temporal frequency resource to carry out downlink transfer, distinguish data by the Beam direction; The user adopts orthogonal time frequency resources to carry out downlink transfer in the group.By the mode that the two-stage orthogonal resource is divided, the maximum like this n of needs RB just can finish transfer of data.Reach the saving transfer resource, improved the purpose of capacity.

The user to be divided into several groups, and the descending Beam mutually orthogonal in grouping back, can save transfer resource simultaneously, must satisfy following condition:

A. to arbitrary Site, same group of user can not occupy whole Beam.

B. the number of users in arbitrary group can not be greater than realizing user's multiplexing number (do not consider based on DOA multiplexing) at most.

If all packet modes for a kind of user distribution scene all can not satisfy above-mentioned two conditions simultaneously, then can not come the lifting capacity by user grouping scheme based on AOA, can only reduce interference between the user this moment by beam shaping.When other condition was constant, the probability of happening of above-mentioned situation (i.e. grouping failure) was subjected to a plurality of condition effect, as:

(1). increase with the Site quantity that participates in cooperation;

(2). the increase with the number of users that participates in dividing increases;

(3) with. the degree of freedom of choosing of total user's group of participate in dividing increases and reduces;

(4). the increase of the wave beam degree of freedom that can realize with each Site reduces;

(5). the numbers of beams increase that can realize with each Site reduces;

(6). reduce with each increase that can divide number of packet.

Grouping algorithm is: at first the wave beam based on site1 carries out user grouping, investigates and divides into groups whether to satisfy condition A, B; Then divide into groups successfully if satisfy; Then do not change a kind of packet mode if do not satisfy, investigate and divide into groups whether to satisfy condition A, B based on site1; If finish the failure of then dividing into groups of packet mode that traversal still can not be met condition after based on the packet mode of site1.

The user packet method based on AOA that this patent proposes can pass through user grouping, utilizes the message capacity of the beam direction orthogonality lifting down link of cooperation site.

Description of drawings

Fig. 1 DLCoMPbeam schematic diagram

Fig. 2 can divide an example of the user wave beam distribution of grouping.

Claims

1. CoMP user packet method of simply estimating based on AOA, it is characterized in that, wave beam zone according to the different site of user's correspondence, the user is divided into groups, two groups of users of zones of different adopt identical temporal frequency resource to carry out downlink transfer, distinguish data by the Beam direction, the user adopts orthogonal time frequency resources to carry out downlink transfer in the group, by the mode of two-stage orthogonal resource division.

2. user packet method according to claim 1 is characterized in that, can pass through user grouping, utilizes the message capacity of the beam direction orthogonality lifting down link of cooperation site, saves transfer resource simultaneously.