Method and apparatus for processing feedback in a wireless communication system

• US 9,225,400 B2
• Filed: 06/27/2014
• Issued: 12/29/2015
• Est. Priority Date: 10/30/2006
• Status: Expired due to Fees

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Pan, Kyle Jung-Lin, Tsai, Allan Y.
• Primary Examiner(s): Ghulamali, Qutbuddin
• Application Number:
  US14/318,495
• Publication Number:
  US 20140314169A1
• Time in Patent Office: 550 Days
• Field of Search: 375/346, 375/267, 375/347
• US Class Current: 1/1
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/063 Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection
• 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: H04B 7/0641 Differential feedback
• CPC Class Codes: H04B 7/065 Variable contents, e.g. long-term or short-short
• CPC Class Codes: H04L 1/0693 Partial feedback, e.g. partial channel state information [CSI]
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0246 with factorisation

Abstract

A method and apparatus for processing feedback implemented in a wireless transmit/receive unit (WTRU) comprises estimating a channel matrix. The effective channel is calculated and a precoding matrix is selected. Feedback bits are generated and transmitted.

Claims

1. A method for processing feedback bits implemented in a wireless transmit/receive unit (WTRU), comprising:

estimating a channel matrix by the wireless WTRU;

calculating an effective channel;

selecting a precoding matrix from a set of precoding matrices;

computing a differential precoding matrix or delta matrix;

quantizing the differential precoding matrix or delta matrix;

generating the feedback bits by the WTRU; and

transmitting the feedback bits from the WTRU, wherein the set of precoding matrices is constructed using a Discrete Fourier Transform (DFT) matrix multiplied with different phase shifts.

2. The method of claim 1 wherein selecting the precoding matrix includes selecting the precoding matrix based upon a metric, wherein the metric includes any one of the following:

signal to interference noise ratio (SINR), throughput, block error rate (BER), frame error rate, and channel capacity.

3. The method of claim 1 wherein the effective channel is a multiplication of the channel estimate with precoding matrices.

4. The method of claim 1 wherein selecting the precoding matrix includes calculating the precoding matrix from the channel matrix estimate.

5. The method of claim 4 wherein selecting the precoding matrix further comprises:

quantizing the precoding matrix using a predetermined codebook.

6. The method of claim 1 wherein the feedback bits include a codeword index.

7. The method of claim 1, further comprising:

updating the precoding matrix.

8. A method for processing feedback bits implemented in a wireless transmit/receive unit (WTRU), comprising:

constructing a set of precoding matrices using a Discrete Fourier Transform (DFT) matrix multiplied with different phase shifts;

selecting a precoding matrix from the set of precoding matrices by the by the wireless WTRU;

computing a differential precoding matrix or delta matrix;

quantizing the differential precoding matrix or delta matrix;

generating the feedback bits by the WTRU; and

transmitting the feedback bits from the WTRU.

9. The method of claim 8 wherein the feedback bits include a codeword index.

10. The method of claim 8, further comprising:

updating the precoding matrix.

11. A wireless transmit/receive unit (WTRU), comprising:

a channel estimator configured to receive a signal and estimate a channel; and

a feedback bit generator in communication with the channel estimator, the feedback bit generator configured to determine a precoding matrix from a set of precoding matrices, generate a differential feedback bit and transmit the differential feedback bit, wherein the set of precoding matrices is constructed using a Discrete Fourier Transform (DFT) matrix multiplied with different phase shifts.

12. The WTRU of claim 11 wherein the feedback bit generator is further configured to generate a binary feedback bit.

13. The WTRU of claim 11 wherein the feedback bit generator is configured to generate a non-differential feedback bit.

14. The WTRU of claim 11 wherein the precoding matrix is determined based upon at least one of:

a signal to interference noise ratio (SINR), a throughput, a block error rate (BER), a frame error rate, or a channel capacity.

15. The WTRU of claim 11, wherein the feedback bit generator is further configured to determine a feedback rate based at least in part on a Doppler adjustment.

16. A wireless transmit/receive unit (WTRU), comprising:

a channel estimator configured to receive a signal and estimate a channel; and

a feedback bit generator in communication with the channel estimator, the feedback bit generator configured to determine a precoding matrix from a set of precoding matrices, generate a binary feedback bit and transmit a binary feedback bit, wherein the set of precoding matrices is constructed using a Discrete Fourier Transform (DFT) matrix multiplied with different phase shifts.

17. The WTRU of claim 16 wherein the feedback bit generator is configured to generate a non-differential feedback bit.

18. The WTRU of claim 16 wherein the feedback bit generator is configured to generate a differential feedback bit.

19. The WTRU of claim 16 wherein the precoding matrix is further determined based upon at least one of:

a signal to interference noise ratio (SINR), a throughput, a block error rate (BER), a frame error rate, or a channel capacity.

20. The WTRU of claim 16, wherein the feedback bit generator is further configured to determine a feedback rate based at least in part on a Doppler adjustment.