Method and apparatus for demodulating signals processed in a transmit diversity mode

• US 7,623,566 B2
• Filed: 01/17/2007
• Issued: 11/24/2009
• Est. Priority Date: 06/14/2000
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Lee, Way-Shing, Rowitch, Douglas Neal, Ekvetchavit, Thunyachate
• Primary Examiner(s): Phu; Phuong
• Application Number:
  US11/624,194
• Publication Number:
  US 20070116101A1
• Time in Patent Office: 1,042 Days
• Field of Search: 375/150, 375/148, 375/140, 375/142, 375/143, 375/147, 375/152, 375/144, 370/529, 370/343, 370/320
• US Class Current: 375/150
• CPC Class Codes: H04B 1/70751 using partial detection H04B1/70758 takes precedence
• CPC Class Codes: H04B 1/70752 Partial correlation
• CPC Class Codes: H04B 1/708 Parallel implementation
• CPC Class Codes: H04B 1/709 Correlator structure
• CPC Class Codes: H04B 7/0613 using simultaneous transmission H04B7/0686 takes precedence
• CPC Class Codes: H04J 13/004 Orthogonal

Abstract

Demodulator architectures for processing a received signal in a wireless communications system. The demodulator includes a number of correlators coupled to a combiner. Each correlator typically receives and despreads input samples (which are generated from the received signal) with a respective despreading sequence to provide despread samples. Each correlator then decovers the despread samples to provide decovered “half-symbols” and further demodulates the decovered half-symbols with pilot estimates to generate correlated symbols. The decovering is performed with a Walsh symbol having a length (T) that is half the length (2T) of a Walsh symbol used to cover the data symbols in the transmitted signal. The combiner selectively combines correlated symbols from the assigned correlators to provide demodulated symbols. One or more correlators can be assigned to process one or more instances of each transmitted signal. The pilot estimates used within each assigned correlator to demodulate the decovered half-symbols are generated based on the signal instance being processed by that correlator.

Claims

1. An apparatus for a communication system, comprising:

a first and second correlator, each correlator including

a decover element for decovering a plurality of received samples to provide decovered half-symbols, wherein the decover element is configured to perform decovering with a decovering channelization symbol having a length (T) that is half the length (2T) of a covering channelization symbol used to cover the received samples;

a first multiplier for receiving the decovered half-symbols and pilot symbols to provide demodulated half-symbols; and

a switch for selectively sending a demodulated half-symbol along a first signal path during a first half of a symbol period and an inverted demodulated half-symbol along a second signal path during a second half of the symbol period.

2. The apparatus of claim 1, wherein the received samples are despread samples, and further comprising:

a second multiplier for producing the despread received samples.

3. The apparatus of claim 1, further comprising:

a conjugator for conjugating the demodulated half-symbols along the second signal path.

4. The apparatus of claim 1, further comprising:

a combiner for combining the demodulated half-symbols received from the first and second signal paths of the respective first and second correlators.

5. The apparatus of claim 4, wherein the combiner comprises:

a first accumulator for accumulating the demodulated half-symbols along the first signal path of the first correlator and the second signal path of the second correlator; and

a second accumulator for accumulating the demodulated half-symbols along the second signal path of the first correlator and the first signal path of the second correlator.

6. A receiver for processing a received signal transmitted from the transmitter, said receiver comprising:

a first and second correlator, each correlator including

a decover element for decovering a plurality of received samples to provide decovered half-symbols, wherein the decover element is configured to perform decovering with a decovering channelization symbol having a length (T) that is half the length (2T) of a covering channelization symbol used to cover the received samples;

a first multiplier for receiving the decovered half-symbols and pilot symbols to provide demodulated half-symbols; and

a switch for selectively sending a demodulated half-symbol along a first signal path during a first half of a symbol period and an inverted demodulated half-symbol along a second signal path during a second half of the symbol period.

7. The receiver of claim 6, wherein the received samples are despread samples, and further comprising:

a second multiplier for producing the despread received samples.

8. The receiver of claim 6, further comprising:

a conjugator for conjugating the demodulated half-symbols along the second signal path.

9. The reciever of claim 6, further comprising:

a combiner for combining the demodulated half-symbols received from the first and second signal paths of the respective first and second correlators.

10. The receiver of claim 9, wherein the combiner comprises:

a first accumulator for accumulating the demodulated half-symbols along the first signal path of the first correlator and the second signal path of the second correlator; and

a second accumulator for accumulating the demodulated half-symbols along the second signal path of the first correlator and the first signal path of the second correlator.

11. A method to demodulate signals, comprising:

decovering a plurality of received samples to provide decovered half symbols, wherein a decover element is configured to perform decovering with a decovering channelization symbol having a length (T) that is half the length (2T) of a covering channelization symbol used to cover the received samples;

receiving the decovered half-symbols and pilot symbols to provide demodulated half-symbols; and

selectively sending a demodulated half-symbol along a first signal path during a first half of a symbol period and an inverted demodulated half-symbol along a second signal path during a second half of the symbol period.

12. The method of claim 11, wherein the received samples are despread samples, and further comprising:

producing the despread received samples.

13. The method of claim 11, further comprising:

a conjugator for conjugating the demodulated half-symbols along the second signal path.

14. The method of claim 11, further comprising:

combining the demodulated half-symbols received from the first and second signal paths of the respective first and second correlators.

15. The method of claim 14, wherein the combining comprises:

accumulating the demodulated half-symbols along the first signal path of the first correlator and the second signal path of the second correlator; and

accumulating the demodulated half-symbols along the second signal path of the first correlator and the first signal path of the second correlator.

16. An apparatus for demodulating signals, comprising:

means for decovering a plurality of received samples to provide decovered half-symbols, wherein the means for decovering is configured to perform decovering with a decovering channelization symbol having a length (T) that is half the length (2T) of a covering channelization symbol used to cover the received samples;

means for receiving the decovered half-symbols and pilot symbols to provide demodulated half-symbols; and

means for selectively sending a demodulated half-symbol along a first signal path during a first half of a symbol period and an inverted demodulated half-symbol along a second signal path during a second half of the symbol period.

17. The apparatus of claim 16, wherein the received samples are despread samples, and further comprising:

means for producing the despread received samples.

18. The apparatus of claim 16, further comprising:

means for conjugating the demodulated half-symbols along the second signal path.

19. The apparatus of claim 16, further comprising:

means for combining the demodulated half-symbols received from the first and second signal paths of the respective first and second correlators.

20. The apparatus of claim 19, wherein the means for combining comprises:

means for accumulating the demodulated half-symbols along the first signal path of the first correlator and the second signal path of the second correlator; and

means for accumulating the demodulated half-symbols along the second signal path of the first correlator and the first signal path of the second correlator.