Method and system for code reuse and capacity enhancement using null steering

• US 8,149,895 B2
• Filed: 12/05/2008
• Issued: 04/03/2012
• Est. Priority Date: 11/02/2001
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Bolourchi, Nadar, Kazakevich, Leonid, Yang, Rui
• Primary Examiner(s): Tran, Khai
• Application Number:
  US12/329,516
• Publication Number:
  US 20090135889A1
• Time in Patent Office: 1,215 Days
• Field of Search: 375/142, 375/130, 375/146, 375/148, 375/199, 375/260, 370/320, 370/335, 370/342
• US Class Current: 375/142
• CPC Class Codes: H01Q 3/2611 Means for null steering; Adaptive interference nulling
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04J 13/0077 Multicode, e.g. multiple codes assigned to one user
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

The number of users and data capacity of wireless systems are increased by employing apparatus and method for increasing the number of spreading codes available in the system by providing a mechanism to reuse the already allocated spreading code or use the codes that may correlate to those already being used within the same sector/cell. This, in return, provides capacity improvement proportional to the number of added base station (BS) antennas for each cell. An antenna null steering technique for code allocation maintains the cross correlation properties of the codes only for the desired user and to obtain a gain in capacity improvement.

Claims

1. Apparatus for wireless communication with at least two mobile units using a null beam steering technique, comprising:

first and second data sources each having data intended for a different one of said mobile units;

first and second units for respectively spreading input data from said first and second data sources, each employing a spreading code for spreading their associated input data, said spreading code being one of a same spreading code or a correlated spreading code;

first and second groups of complex weighting values respectively associated with said first and second data sources, each group of complex weighting values being respectively supplied to inputs of first and second groups of circuits, each of said first and second groups of circuits respectively receiving an output of said first and second units, for multiplying each received output responsive to an associated complex weighting value input;

an antenna array comprising a given number of antennas which is greater than a number of data sources; and

a third group of circuits each combining an output of one of said circuits in said first group with an associated one of said circuits of said second group and delivering an output of each circuit of said third group to an associated one of said antennas in said array, said antennas being arranged to limit the mobile units to receipt of data from only one of said data sources.

2. The apparatus as claimed in claim 1, wherein N remote users are configured to receive data, and the number of antennas in the antenna array is N+1.

3. The apparatus of claim 2, wherein the number of complex weighting value inputs in each group is N+1.

4. The apparatus of claim 2, wherein the number of combining circuits is N+1.

5. The apparatus of claim 1, wherein said first and second spreading units both employ a given spreading code.

6. The apparatus of claim 1, wherein said first and second spreading units employ correlated spreading codes.

7. The apparatus of claim 1, wherein said circuits of said third group are summing circuits.

8. The apparatus of claim 1, wherein the antennas are spaced apart in a given manner.

9. The apparatus of claim 1, wherein the antennas are arranged in a linear manner.

10. The apparatus of claim 1, wherein the antennas are arranged in a linear manner and spaced at predetermined intervals.

11. The apparatus of claim 1, wherein the complex weighting inputs are a function of the number of antennas in the array.

12. The apparatus of claim 11, wherein on a condition that data is sent to two remote units, complex weighting values of the one group of complex weighting inputs are selected to provide a power of a communication received by a first one of the remote users which is maximized.

13. The apparatus of claim 12, wherein said one group of complex weighting values are selected so that a power of a communication received by a second one of the remote users is minimized.

14. The apparatus of claim 13, wherein complex weighting values of a remaining one of said groups of complex weighting inputs are selected so that a power of a communication received by a second one of the remote users is maximized.

15. The apparatus of claim 14, wherein complex weighting values of said remaining one of said groups of complex weighting inputs are selected so that a power of a communication received by a the first one of the remote users is maximized.

16. The apparatus of claim 1, wherein said first and second groups of circuits are modulators.

17. The apparatus of claim 1, wherein said apparatus is employed by a base station.

18. The apparatus of claim 1, wherein the antennas are arranged to provide beam steering.

19. The apparatus of claim 1, wherein said first and second groups of circuits are amplifiers each having a gain adjustable responsive to a complex weighting input applied thereto.