METHOD AND APPARATUS FOR DOWNLINK BEAM FORMING IN TD-CDMA SYSTEM

• US 20110003552A1
• Filed: 01/09/2007
• Published: 01/06/2011
• Est. Priority Date: 01/18/2006
• Status: Active Grant

• Current Assignee: Shanghai Ultimate Power Communications Technology Co., Ltd.
• Original Assignee: Shanghai Ultimate Power Communications Technology Co., Ltd.
• Inventors: Sun, Changguo, Wu, Na, Wang, Yingmin
• Granted Patent: US 8,811,904 B2
• Time in Patent Office: Days
• US Class Current: 455/63.1
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 72/541 using the level of interference

Abstract

The present invention discloses a method and an apparatus for downlink beam forming in a TD-CDMA system. The method includes: acquiring the spatial covariance matrixes of all uplink slot interference user signals and the downlink slots in which the interference user signals locate; obtaining the interference spatial covariance matrixes of each downlink slot based on the downlink slots in which the interference user signals locate and the spatial covariance matrixes of the interference user signals; determining the beam forming weight coefficient of downlink expected user signals based on the interference spatial covariance matrixes of each downlink slot and the spatial covariance matrixes of the downlink expected user signals; implementing beam forming based on the beam forming weight coefficient of downlink expected user signals. The invention determines the downlink slots in which all interference user signals locate and calculates the interference spatial covariance matrixes of all downlink slots, so that the beam forming weight coefficients of all downlink expected user signals are obtained to implement beam forming. Therefore, the beam forming method in the invention is feasible in the cases of both slot symmetry and slot asymmetry.

Claims

1. A downlink beam forming method in a TD-CDMA system, comprising:

acquiring spatial covariance matrixes of all uplink slot interference user signals and downlink slots in which the interference user signals locate;

obtaining an interference spatial covariance matrix of each downlink slot based on the downlink slots in which the interference user signals locate and the spatial covariance matrixes of the interference user signals;

determining beam forming weight coefficients of downlink expected user signals based on the interference spatial covariance matrixes of each downlink slot and spatial covariance matrixes of downlink expected user signals; and

implementing beam forming based on the beam forming weight coefficients of the downlink expected user signals.

2. The downlink beam forming method in a TD-CDMA system according to claim 1, wherein, the step of acquiring downlink slots in which the interference user signals locate comprises:

acquiring from a corresponding relationship between the uplink slots and the downlink slots in which all predefined cell user signals locate;

or

a base station acquiring sequence numbers of the downlink slots in which the interference user signals locate from a radio network controller;

or

if interference user signals are all in cells controlled by a same base station, the base station obtaining sequence numbers of the downlink slots in which the interference user signals locate by looking up a table.

3. The downlink beam forming method in a TD-CDMA system according to claim 1, wherein,

channel estimation is applied to all uplink slot interference user signals by a channel estimator to obtain the spatial covariance matrixes of the interference user signals

R_I^(m)=E{H_I^(m)H_I^(m)H}, m=1, . . . , M,

wherein, m is the sequence number of the interference user signal, M m) represents M interference user signals totally, H_I^(m) represents multiple antenna channel estimation of the m^th interference user, and H_I^(m)H represents a conjugate transpose operation of H_I^(m).

4. The downlink beam forming method in a TD-CDMA system according to claim 1, wherein, a formula to calculate the interference spatial covariance matrixes of the downlink slots is

5. The downlink beam forming method in a TD-CDMA system according to claim 1, wherein, a formula to calculate the beam forming weight coefficients of the downlink expected user signals is

6. The downlink beam forming method in a TD-CDMA system according to claim 1, wherein, the beam forming method comprises determining transmitting sequences of the downlink expected user signals at all antennas and a formula to calculate the transmitting sequences is

7. The downlink beam forming method in a TD-CDMA system according to claim 1, wherein, the step of beam forming is implemented by a multiple user signal beam former.

8. A downlink beam forming apparatus in a TD-CDMA system, comprising:

an inference user information acquiring module, for acquiring spatial covariance matrixes of all uplink slot interference user signals and the downlink slots in which the interference user signals locate;

a spatial covariance matrix acquiring module, for acquiring spatial covariance matrixes of the uplink interference user signals, and obtaining interference spatial covariance matrixes of the downlink slots based on the downlink slots in which the uplink interference user signals locate, and acquiring spatial covariance matrixes of downlink expected user signals;

a beam forming weight coefficient acquiring module, for determining the beam forming weight coefficients of the downlink expected user signals based on the interference spatial covariance matrixes of each downlink slot and the spatial covariance matrixes of the downlink expected user signals; and

a beam forming module, for implementing beam forming based on the beam forming weight coefficients of the downlink expected user signals.

9. The downlink beam forming apparatus in a TD-CDMA system according to claim 8, wherein, acquiring the downlink slots in which the interference user signals locate by the interference user information acquiring module comprises:

acquiring from a corresponding relationship between the uplink slots and the downlink slots in which all predefined cell user signals locate;

or

acquiring sequence numbers of the downlink slots in which the interference user signals locate from a radio network controller;

or

for the interference user signals in cells controlled by a same base station, the base station obtaining sequence numbers of the downlink slots in which the interference user signals locate by looking up a table.

10. The downlink beam forming apparatus in a TD-CDMA system according to claim 8, wherein,

the spatial covariance matrix acquiring module utilizing a channel estimator to apply channel estimation to all uplink slot interference user signals to obtain the spatial covariance matrixes of the interference user signals

R_I^(m)=E{H_I^(m)H_I^(m)H}, m=1, . . . , M,

wherein m is the sequence number of the interference user signal, M represents there are M interference user signals totally, H_I^(m) represents multiple antenna channel estimation of the m^th interference user, and H_I^(m)H represents a conjugate transpose operation of H_I^(m).

11. The downlink beam forming apparatus in a TD-CDMA system according to claim 9, wherein, the spatial covariance matrix acquiring module acquires the interference spatial covariance matrixes of the downlink slots by the formula of

12. The downlink beam forming apparatus in a TD-CDMA system according to claim 10, wherein, the spatial covariance matrix acquiring module acquires the interference spatial covariance matrixes of the downlink slots by a formula of

13. The downlink beam forming apparatus in a TD-CDMA system according to claim 8, wherein, the beam forming weight coefficient acquiring module acquires the beam forming weight coefficients of the downlink expected user signals by a formula of

14. The downlink beam forming apparatus in a TD-CDMA system according to claim 8, wherein, the beam forming module is used to determine transmitting sequences of the downlink expected user signals at all antennas and a formula to calculate the transmitting sequences is

15. The downlink beam forming apparatus in a TD-CDMA system according to claim 8, wherein, the beam forming module is implemented by a multiple user signal beam former.

16. The downlink beam forming apparatus in a TD-CDMA system according to claim 14, wherein, the beam forming module is implemented by a multiple user signal beam former.