METHOD AND APPARATUS FOR PERFORMING SPATIAL-DIVISION MULTIPLE ACCESS

• US 20070183362A1
• Filed: 02/06/2006
• Published: 08/09/2007
• Est. Priority Date: 02/06/2006
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Zhuang, Xiangyang, Mondal, Bishwarup, Thomas, Timothy, Baum, Kevin, Vook, Frederick
• Granted Patent: US 7,426,198 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0639 Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method and apparatus for performing spatial-division multiple access within a communication system is provided herein. During operation, nodes will return null subspace information along with their channel subspace information. The null subspace is similar to the channel subspace except that the null subspace information directs a base station to the matrix in a predefined codebook that results in minimum power being received at the node. The null subspace for each node is taken into consideration when communicating with a particular node.

Claims

1. A method comprising the steps of:

transmitting pilot data to a first and a second node from multiple antennas;

receiving a first and a second channel subspace information from the first and the second nodes in response to the transmission;

receiving first and second null subspace information from the node in response to the transmission;

utilizing the first channel subspace information and the second null subspace information to determine antenna weights for the first node;

utilizing the second channel subspace information and the first null subspace information to determine antenna weights for the second node; and

transmitting data to the first and the second nodes simultaneously utilizing the first and the second antenna weights, respectively.

2. The method of claim 1 wherein the channel subspace information comprises a codebook entry.

3. The method of claim 1 wherein the null subspace information comprises a codebook entry.

4. The method of claim 1 wherein first channel subspace information comprises a codebook entry that maximizes transmit energy to the first node and the second channel subspace information comprises a codebook entry that maximizes energy to the second node.

5. The method of claim 1 wherein first null subspace information comprises a codebook entry that is used to minimize transmit energy to the first node and the second null subspace information comprises a codebook entry that is used to minimize energy to the second node.

6. A method comprising the steps of:

receiving pilot data from a base station that is transmitted from multiple antennas;

determining channel subspace information based on the received pilot data;

determining null subspace information based on the received pilot data; and

transmitting the channel subspace information and the null subspace information for use by the base station in determining antenna weights.

7. The method of claim 6 further comprising the step of:

receive beamformed transmissions that utilize the channel subspace information.

8. The method of claim 7 wherein the channel subspace information comprises a codebook entry.

9. The method of claim 7 wherein the null subspace information comprises a codebook entry.

10. The method of claim 7 wherein the channel subspace information comprises a codebook entry that maximizes transmit energy received from a base station.

11. The method of claim 7 wherein the null subspace information comprises a codebook entry that minimizes transmit energy received from a base station.

12. An apparatus comprising:

a transmitter transmitting pilot data;

a receiver receiving first and second channel subspace information from a first and a second node and first and second null subspace information from the first and the second node; and

stream weighting circuitry utilizing the first channel subspace information and the second null subspace information to determine first antenna/stream weights for the first node, the stream weighting circuitry additionally utilizing the second channel subspace information and the first null subspace information to determine second antenna/stream weights for the second node.

13. The apparatus of claim 12 wherein the transmitter additionally transmits information to the first and the second nodes simultaneously utilizing the first and the second antenna/stream weights.

14. The apparatus of claim 12 wherein the channel subspace information comprises a first and a second codebook entry.

15. The apparatus of claim 12 wherein the first and the second null subspace information comprises a first and a second codebook entry.

16. The apparatus of claim 12 wherein first channel subspace information comprises a codebook entry that maximizes transmit energy to the first node and the second channel subspace information comprises a codebook entry that maximizes energy to the second node.

17. The apparatus of claim 12 wherein first null subspace information comprises a codebook entry that is used to minimize transmit energy to the first node and the second null subspace information comprises a codebook entry that is used to minimize energy to the second node.

18. An apparatus comprising:

a receiver receiving pilot data from a base station that is transmitted from multiple antennas;

logic circuitry determining channel subspace information based on the received pilot data and determining null subspace information based on the received pilot data; and

transmitting circuitry transmitting the channel subspace information and the null subspace information for use by the base station in determining antenna weights.

19. The apparatus of claim 18 wherein the receiver additionally receives beamformed transmissions that utilize the channel subspace information.

20. The apparatus of claim 18 wherein the channel subspace information comprises a codebook entry that maximizes transmit energy received from a base station and wherein the null subspace information comprises a codebook entry that minimizes transmit energy received from a base station.