METHOD AND APPARATUS FOR DEMODULATING SIGNALS PROCESSED IN A TRANSMIT DIVERSITY MODE

• US 20070116102A1
• Filed: 01/17/2007
• Published: 05/24/2007
• Est. Priority Date: 06/14/2000
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Lee, Way-Shing, Rowitch, Douglas, Ekvetchavit, Thunyachate
• Granted Patent: US 7,684,474 B2
• Time in Patent Office: Days
• US Class Current: 375/148
• 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 switch for selectively outputting the decovered half-symbols corresponding to a first half of a symbol period along a first signal path and decovered half-symbols corresponding to a second half of the symbol period along a second signal path;

first and second summers, respectively coupled to the first and second signal paths, for combining each pair of decovered half-symbols to provide a respective decovered symbol; and

first and second multipliers for receiving the decovered symbols and pilot symbols to provide demodulated symbols.

2. The apparatus of claim 1, wherein the received samples are despread received samples, said first and second correlator further including:

a third multiplier for producing the despread received samples.

3. The apparatus of claim 1, further comprising:

a conjugator for conjugating the decovered symbols along the second signal path of the first correlator and the first signal path of the second correlator.

4. The apparatus of claim 1, further comprising:

a delay element for delaying the decovered half-symbols along the first signal path.

5. The apparatus of claim 1, further comprising:

a combiner for combining the demodulated symbols received from the first and second correlators.

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

a first accumulator for accumulating the demodulated symbols from the first multiplier of the first and second correlators; and

a second accumulator for accumulating the demodulated symbols from the second multiplier of the first and second correlators.

7. A communication system, comprising:

a transmitter; and

a receiver for processing a received signal transmitted from the transmitter, said receiver including;

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 switch for selectively outputting the decovered half-symbols corresponding to a first half of a symbol period along a first signal path and decovered half-symbols corresponding to a second half of the symbol period along a second signal path;

first and second summers, respectively coupled to the first and second signal paths, for combining each pair of decovered half-symbols to provide a respective decovered symbol; and

first and second multipliers for receiving the decovered symbols and pilot symbols to provide demodulated symbols.

8. The communication system of claim 7, wherein the received samples are despread received samples, said first and second correlator further including:

a third multiplier for producing the despread received samples.

9. The communication system of claim 7, further comprising:

a conjugator for conjugating the decovered symbols along the second signal path of the first correlator and the first signal path of the second correlator.

10. The communication system of claim 7, further comprising:

a delay element for delaying the decovered half-symbols along the first signal path.

11. The communication system of claim 7, further comprising:

a combiner for combining the demodulated symbols received from the first and second correlators.

12. The communication system of claim 11, wherein the combiner comprises:

a first accumulator for accumulating the demodulated symbols from the first multiplier of the first and second correlators; and

a second accumulator for accumulating the demodulated symbols from the second multiplier of the first and second correlators.