MULTI-USER MULTI-STREAM BEAMFORMING METHOD, APPARATUS, AND BASE STATION

• US 20140086086A1
• Filed: 11/26/2013
• Published: 03/27/2014
• Est. Priority Date: 05/27/2011
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: ZHANG, Yi, ZHOU, Hua, WU, Jianming, GUO, Aihuang, LUO, Wei
• Granted Patent: US 9,287,955 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04W 72/541 using the level of interference

Abstract

The present invention relates to a multi-user multi-stream beamforming method and apparatus, and a base station. The multi-user multi-stream beamforming method includes the steps of: a) calculating a beamforming matrix of each user in the multi-user according to a minimum leakage principle; b) determining a user average Signal to Leakage Noise Ratio (SLNR) of the multi-user according to the beamforming matrix of each user; c) determining whether the user average SLNR is stable, and if the user average SLNR is not stable, returning to step a) to recalculate the beamforming matrix of each user by using the calculated beamforming matrix of each user.

Claims

1. A multi-user multi-stream beamforming method, comprising the steps of:

a) calculating a beamforming matrix of each user in the multi-user according to a minimum leakage principle;

b) determining a user average Signal to Leakage Noise Ratio (SLNR) of the multi-user according to the beamforming matrix of each user; and

c) determining whether the user average SLNR is stable, and if not stable, returning to step a) to recalculate the beamforming matrix of each user by using the calculated beamforming matrix of each user.

2. The method according to claim 1, wherein step a) comprising:

1) determining an initial received-merged matrix of each user in the multi-user, or determining an updated received-merged matrix of each user according to the previously calculated beamforming matrix of each user;

2) calculating a singular solution based on the initial received-merged matrix or the updated received-merged matrix of each user according to the minimum leakage principle; and

3) determining a beamforming matrix of each user by using the singular solution.

3. The method according to claim 2, wherein,

in step 1), the initial received-merged matrix of each user is calculated by using the following equation:

4. The method according to claim 1, wherein in step c), it is further judged whether step c) has performed a predetermined number of determinations, or whether step a) has performed a predetermined number of calculations of the beamforming matrix of each user, and the processing ends if the predetermined number of determinations or the predetermined number of calculations of the beamforming matrix of each user have been performed.

5. The method according to claim 1, wherein,

if |SLNR_(i)−

SLNR<sup>(i−

1)</sup>|≦

δ

(δ

is a predetermined number), then it is judged that the user average SLNR is stable, where i represents a number of iterations, SLNR⁽ⁱ⁾ represents a user average SLNR obtained at the i^th iteration.

6. The method according to claim 1, wherein in step a), the received-merged matrix is updated according to a receiver type, and the beamforming matrix of each user is recalculated by using the calculated beamforming matrix of each user.

7. The method according to claim 1, further comprising the following steps with respect to each user in the multi-user:

judging whether there is a data stream to be retransmitted; and

when there is a data stream to be retransmitted, selecting a beamforming vector corresponding to a channel having good channel quality from the beamforming matrix of the user and allocating to the data stream.

8. A multi-user multi-stream beamforming method, comprising the following steps with respect to each user in the multi-user:

a) determining a beamforming matrix of the user;

b) determining whether there is a data stream to be retransmitted; and

c) when it is determined that there is a data stream to be retransmitted, selecting a beamforming vector corresponding to a channel having good channel quality from the beamforming matrix of the user and allocating to the data stream.

9. The method according to claim 8, wherein in step a), the beamforming matrix of the user is determined according to a minimum leakage principle.

10. The method according to claim 8, comprising the steps of:

determining a user average SLNR of the multi-user according to the beamforming matrix of each user; and

determining whether the user average SLNR is stable, and if not stable, returning to step a) to recalculate the beamforming matrix of each user by using the calculated beamforming matrix of each user.

11. A multi-user multi-stream beamforming apparatus, comprising:

a beamforming matrix calculating unit configured to calculate a beamforming matrix of each user in the multi-user according to a minimum leakage principle;

a user average SLNR calculating unit configured to determine a user average SLNR of the multi-user according to the beamforming matrix of each user; and

a user average SLNR stableness judging unit configured to determine whether the user average SLNR is stable,

wherein if the user average SLNR is not stable, the beamforming matrix calculating unit recalculates the beamforming matrix of each user by using the calculated beamforming matrix of each user.

12. The apparatus according to claim 11, wherein the beamforming matrix calculating unit comprises:

an initial received-merged matrix calculating unit configured to determine an initial received-merged matrix of each user in the multi-user;

an updated received-merged matrix calculating unit configured to determine an updated received-merged matrix of each user according to the previously calculated beamforming matrix of each user;

a singular solution calculating unit configured to calculate a singular solution based on the initial received-merged matrix or the updated received-merged matrix of each user according to the minimum leakage principle; and

a beamforming matrix determining unit configured to determine a beamforming matrix of each user by using the singular solution.

13. The apparatus according to claim 11, further comprising an iteration judging unit configured to judge whether the user average SLNR stableness judging unit has performed a predetermined number of determinations, or whether the beamforming matrix calculating unit has performed a predetermined number of calculations of the beamforming matrix of each user, and end the processing if the predetermined number of determinations or the predetermined number of calculations of the beamforming matrix of each user have been performed.

14. The apparatus according to claim 11, further comprising:

a retransmitted data stream judging unit configured to judge whether there is a data stream to be retransmitted with respect to each user in the multi-user; and

an optimized beamforming vector allocating unit configured to select, when the retransmitted data stream judging unit judges that a user requires a data stream to be retransmitted, a beamforming vector corresponding to a channel having good channel quality from the beamforming matrix of the user and allocate to the data stream.

15. The apparatus according to claim 11, wherein the updated received-merged matrix calculating unit updates the received-merged matrix according to a receiver type, and recalculates the beamforming matrix of each user by using the calculated beamforming matrix of each user.

16. A base station, comprising the multi-user multi-stream beamforming apparatus according to claim 11.