Method and apparatus for interference cancellation in a communication system

• US 6,788,733 B1
• Filed: 11/09/2000
• Issued: 09/07/2004
• Est. Priority Date: 11/09/2000
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc., Yonsei University
• Original Assignee: Qualcomm, Inc.
• Inventors: Kwon, Hyuck-Chan, Whang, Keum-Chan
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Wang, Ted
• Application Number:
  US09/711,108
• Time in Patent Office: 1,398 Days
• Field of Search: 375/148, 375/341, 375/340, 375/147, 375/152, 375/142, 375/150, 375/144, 370/332, 370/335, 370/522, 370/347, 370/208, 455/522, 455/69, 455/422.1, 342/457
• US Class Current: 375/148
• CPC Class Codes: H04B 1/7107 Subtractive interference cancellation
• CPC Class Codes: H04L 1/005 Iterative decoding, including iteration between signal detection and decoding operation
• CPC Class Codes: H04L 1/0066 Parallel concatenated codes

Abstract

A novel and improved method and apparatus in a communication system (100) provides for efficient processing of received signals. The method and apparatus includes converting an encoded and spectrum spread received signal to received samples, determining a first channel estimate based on a first set of pilot signal samples. The first set of pilot signal samples are included in the received samples. The received samples are passed through a correlation and decoding process in accordance with the first channel estimate to produce decoded received samples. The decoded received samples are re-encoded and re-spreaded to produce re-encoded and re-spread samples. The re-encoded and re-spread samples are modified based on the first channel estimate to produce channel modified re-encoded and re-spread samples. The received samples pass through an interference cancellation that uses the channel modified re-encoded and re-spread samples to produce a new set of received samples.

Claims

1. In a communication system, a method comprising:

converting an encoded and spectrum spread received signal to received samples;

determining a first channel estimate based on a first set of pilot signal samples, wherein said first set of pilot signal samples are included in said received samples;

correlating and decoding said received samples in accordance with said first channel estimate to produce decoded received samples;

re-encoding and re-spreading said decoded received samples to produce re-encoded and re-spread samples;

modifying said re-encoded and re-spread samples based on said first channel estimate to produce channel modified re-encoded and re-spread samples, wherein said modifying includes multiplying said re-encoded and re-spread samples by said first channel estimate to produce said channel modified re-encoded and re-spread samples.

2. The method as recited in claim 1 further comprising:

performing interference cancellation on said received samples by using said channel modified re-encoded and re-spread samples to produce a new set of received samples.

3. The method as recited in claim 2 further comprising:

determining a second channel estimate based on a second set of pilot signal samples, wherein said second set of pilot samples are included in said new set of received samples,

correlating and decoding said new received samples in accordance with said second channel estimate to produce new decoded received samples.

4. The method as recited in claim 3 further comprising:

re-encoding and re-spreading said new decoded received samples to produce new re-encoded and re-spread samples;

modifying said new re-encoded and re-spread samples based on said second channel estimate to produce new channel modified re-encoded and re-spread samples.

5. The method as recited in claim 4 wherein said modifying includes multiplying said new re-encoded and re-spread samples by said second channel estimate to produce said new channel modified re-encoded and re-spread samples.

6. The method as recited in claim 4 further comprising:

performing interference cancellation on said new set of received samples by using said new channel modified re-encoded and re-spread samples to produce another new set of received samples.

7. The method as recited in claim 1 wherein said decoding said received samples is performed in accordance with a turbo decoding process.

8. The method as recited in claim 3 wherein said decoding said new received samples is performed in accordance with a turbo decoding process.

9. The method as recited in claim 1 wherein said decoding said received samples is performed in accordance with a convolutional decoding process.

10. The method as recited in claim 3 wherein said decoding said new received samples is performed in accordance with a convolutional decoding process.

11. The method as recited in claim 2 further comprising:

determining whether a cyclic redundancy check of a result of said decoding said received samples passes,

wherein said performing interference cancellation of said received samples is based on whether said cyclic redundancy check passes.

12. The method as recited in claim 6 further comprising:

determining whether a cyclic redundancy check of a result of said decoding said new received samples passes,

wherein said performing interference cancellation on said new set of received samples is based on whether said cyclic redundancy check passes.

13. The method as recited in claim 1 wherein said first set of pilot signal samples are based on a pilot signal transmitted from a source of said received signal.

14. The method as recited in claim 3 further comprising:

utilizing a result of said decoding said received samples in assisting said decoding of said new set of received samples.

15. In a communication system, an apparatus comprising:

a radio frequency receiver for converting an encoded and spectrum spread received signal to received samples;

a searcher in combination with a finger element for determining a channel estimate based on a set of pilot signal samples, wherein said set of pilot signal samples are included in said received samples;

a decoder for decoding said received samples in accordance with said channel estimate to produce decoded received samples;

a controller for re-encoding and re-spreading said decoded received samples to produce re-encoded and re-spread samples, and for modifying said re-encoded and re-spread samples based on said channel estimate to produce channel modified re-encoded and re-spread samples, wherein said controller performs said modifying by multiplying said re-encoded and re-spread samples by said first channel estimate to produce said channel modified re-encoded and re-spread samples.

20. The apparatus as recited in claim 15 wherein said decoder decodes said received samples is in accordance with a turbo decoding process.

21. The apparatus as recited in claim 15 wherein said decoder decodes said received samples is in accordance with a convolutional decoding process.

16. In a communication system, an apparatus comprising:

a radio frequency receiver for converting an encoded and spectrum spread received signal to received samples;

a searcher in combination with a finger element for determining a channel estimate based on a set of pilot signal samples, wherein said set of pilot signal samples are included in said received samples;

a decoder for decoding said received samples in accordance with said channel estimate to produce decoded received samples;

a controller for re-encoding and re-spreading said decoded received samples to produce re-encoded and re-spread samples, and for modifying said re-encoded and re-spread samples based on said channel estimate to produce channel modified re-encoded and re-spread samples, wherein said controller performs interference cancellation on said received samples by using said channel modified re-encoded and re-spread samples to produce a new set of received samples.

17. The apparatus as recited in claim 16 wherein said searcher in combination with said finger element determines a second channel estimate based on a second set of pilot signal samples, wherein said second set of pilot samples are included in said new set of received samples, and said decoder is configured to decode said new set of received samples in accordance with said second channel estimate to produce new decoded received samples.

18. The apparatus as recited in claim 17 wherein said controller re-encodes and re-spreads said new decoded received samples to produce new re-encoded and re-spread samples, and modifies said new re-encoded and re-spread samples based on said second channel estimate to produce new channel modified re-encoded and re-spread samples.

19. The apparatus as recited in claim 18 wherein said controller performs interference cancellation on said new set of received samples by using said new channel modified re-encoded and re-spread samples to produce another new set of received samples.

22. The apparatus as recited in claim 19 wherein said controller determines whether a cyclic redundancy check of a result of said decoding said new received samples passes, and wherein said interference cancellation is based on whether said cyclic redundancy check passes.