Multiplexed CDMA and GPS searching

• US 20030128747A1
• Filed: 01/07/2002
• Published: 07/10/2003
• Est. Priority Date: 01/07/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Zou, Qiuzhen, Poon, Wang Paul
• Granted Patent: US 7,738,533 B2
• Time in Patent Office: Days
• US Class Current: 375/148
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: H04B 1/70754 Setting of search window, i.e. range of code offsets to be searched H04B1/70758 takes precedence
• CPC Class Codes: H04B 1/70758 Multimode search, i.e. using multiple search strategies
• CPC Class Codes: H04B 1/708 Parallel implementation
• CPC Class Codes: H04B 2201/70711 with modular structure

Abstract

Searcher hardware is multiplexed to perform simultaneous searches in either an IS-95 CDMA mode or a GPS mode. In the IS-95 mode, the search hardware is time-multiplexed into a number of searcher time slices, each of which can generate a PN sequence to despread a data sequence. In the GPS mode, the search hardware is configured as a number of distinct GPS channels, each of which can generate a Gold code sequence for tracking a GPS signal from a particular GPS satellite. This configuration allows the searcher to perform multiple GPS signal searches simultaneously. Signal searching in both IS-95 and GPS modes is performed at significantly higher speeds compared to conventional searcher hardware. Moreover, the search hardware can be dynamically configured to operate in either the IS-95 or the GPS mode, eliminating the need for dedicated circuitry for each mode of operation.

Claims

1. A method comprising:

simultaneously executing a plurality of independent searches; and

configuring a demodulator of a wireless communication device as a function of results from the independent searches.

2. The method of claim 1, wherein each independent search is associated with a distinct set of search parameters.

3. The method of claim 2, wherein the search parameters comprise at least one of a window size, a coherent accumulation length, a non-coherent accumulation length, and a PN offset.

4. The method of claim 1, further comprising selecting a search mode from a plurality of search modes.

5. The method of claim 4, wherein the selected search mode is a GPS mode.

6. The method of claim 5, further comprising allocating portions of a channel search hardware to perform the independent searches in parallel.

7. The method of claim 5, wherein configuring the demodulator as a function of the results from the independent searches comprises:

despreading received data;

generating a coherent accumulation result as a function of the despread data; and

configuring the demodulator as a function of the coherent accumulation result.

8. The method of claim 4, wherein the selected search mode is an IS-95 mode.

9. The method of claim 8, wherein simultaneously executing the plurality of independent searches comprises time-multiplexing channel search hardware to perform the plurality of searches.

10. The method of claim 8, wherein configuring the demodulator as a function of the results from the independent searches comprises:

despreading received data;

generating coherent accumulation results as a function of the despread data;

computing energy values as a function of the coherent accumulation results;

generating non-coherent accumulation results as a function of the energy values;

identifying a plurality of energy peaks as a function of the non-coherent accumulation results;

sorting the plurality of energy peaks; and

configuring the demodulator as a function of the sorted energy peaks.

11. A method comprising:

configuring channel search hardware to perform a plurality of simultaneously executed independent searches in one of a GPS mode and an IS-95 mode;

for each independent search, despreading received data;

generating coherent accumulation results as a function of the despread data;

in the GPS mode, configuring a demodulator as a function of the coherent accumulation results; and

in the IS-95 mode,

computing energy values as a function of the coherent accumulation results,

generating non-coherent accumulation results as a function of the energy values,

identifying a plurality of energy peaks as a function of the non-coherent accumulation results,

sorting the plurality of energy peaks, and

configuring the demodulator as a function of the sorted energy peaks.

12. The method of claim 11, wherein the received data comprises I and Q quadrature components of at least one of gain-adjusted I/Q data, center band I/Q data, lower band I/Q data, and higher band I/Q data.

13. A processor readable medium containing processor executable instructions for:

simultaneously executing a plurality of independent searches; and

configuring a demodulator of a wireless communication device as a function of results from the independent searches.

14. The processor readable medium of claim 13, wherein each independent search is associated with a distinct set of search parameters.

15. The processor readable medium of claim 14, wherein the search parameters comprise at least one of a window size, a coherent accumulation length, a non-coherent accumulation length, and a PN offset.

16. The processor readable medium of claim 13, containing further instructions for selecting a search mode from a plurality of search modes.

17. The processor readable medium of claim 16, wherein the selected search mode is a GPS mode.

18. The processor readable medium of claim 17, containing further instructions for allocating portions of a channel search hardware to perform the independent searches in parallel.

19. The processor readable medium of claim 17, containing further instructions for:

despreading received data;

generating a coherent accumulation result as a function of the despread data; and

configuring the demodulator as a function of the coherent accumulation result.

20. The processor readable medium of claim 16, wherein the selected search mode is an IS-95 mode.

21. The processor readable medium of claim 20, containing further instructions for time-multiplexing channel search hardware to perform the plurality of searches.

22. The processor readable medium of claim 20, containing further instructions for:

despreading received data;

generating coherent accumulation results as a function of the despread data;

computing energy values as a function of the coherent accumulation results;

generating non-coherent accumulation results as a function of the energy values;

identifying a plurality of energy peaks as a function of the non-coherent accumulation results;

sorting the plurality of energy peaks; and

configuring the demodulator as a function of the sorted energy peaks.

23. A processor readable medium containing processor executable instructions for:

configuring channel search hardware to perform a plurality of simultaneously executed independent searches in one of a GPS mode and an IS-95 mode;

for each independent search, using a matched filter to despread received data;

generating coherent accumulation results as a function of the despread data;

in the GPS mode, configuring a demodulator as a function of the coherent accumulation results; and

in the IS-95 mode,

computing energy values as a function of the coherent accumulation results,

generating non-coherent accumulation results as a function of the energy values,

identifying a plurality of energy peaks as a function of the non-coherent accumulation results,

sorting the plurality of energy peaks, and

configuring the demodulator as a function of the sorted energy peaks.

24. An apparatus comprising:

a channel search module configured to perform a plurality of simultaneously executed independent searches in one of a GPS mode and an IS-95 mode; and

a modem to demodulate a signal based on results from the searches.

25. The apparatus of claim 24, wherein the channel search module comprises a control module to configure the channel search module as a plurality of simultaneously operating GPS channels in the GPS mode and to configure the channel search as a plurality of time-multiplexed searcher time slices in the IS-95 mode.

26. The apparatus of claim 24, wherein the channel search module comprises a matched filter to despread received data, the matched filter comprising an adder arrangement configured to output a first sum in the GPS mode and a second sum in the IS-95 mode.

27. The apparatus of claim 24, wherein the channel search module comprises a PN generator to generate a PN sequence in the IS-95 mode and a set of PN sequences in the GPS mode.

28. The apparatus of claim 24, wherein the channel search module comprises a coherent accumulator arrangement configured to generate a coherent accumulation result in the IS-95 mode and to generate a set of coherent accumulation results in the GPS mode.

29. The apparatus of claim 28, wherein the channel search module configures the modem as a function of the set of coherent accumulation results in the GPS mode.

30. An apparatus comprising:

means for simultaneously executing a plurality of independent searches; and

means for configuring a demodulator of a wireless communication device as a function of results from the independent searches.

31. The apparatus of claim 30, wherein each independent search is associated with a distinct set of search parameters.

32. The apparatus of claim 31, wherein the search parameters comprise at least one of a window size, a coherent accumulation length, a non-coherent accumulation length, and a PN offset.

33. The apparatus of claim 30, further comprising means for selecting a search mode from a plurality of search modes.

34. The apparatus of claim 33, wherein the selected search mode is a GPS mode.

35. The apparatus of claim 34, further comprising means for allocating portions of a channel search hardware to perform the independent searches in parallel.

36. The apparatus of claim 34, further comprising:

means for despreading received data;

means for generating a coherent accumulation result as a function of the despread data; and

means for configuring the demodulator as a function of the coherent accumulation result.

37. The apparatus of claim 33, wherein the selected search mode is an IS-95 mode.

38. The apparatus of claim 37, further comprising means for time-multiplexing channel search hardware to perform the plurality of searches.

39. The apparatus of claim 37, further comprising:

means for despreading received data;

means for generating coherent accumulation results as a function of the despread data;

means for computing energy values as a function of the coherent accumulation results;

means for generating non-coherent accumulation results as a function of the energy values;

means for identifying a plurality of energy peaks as a function of the non-coherent accumulation results;

means for sorting the plurality of energy peaks; and

means for configuring the demodulator as a function of the sorted energy peaks.

40. An apparatus comprising:

means for configuring channel search hardware to perform a plurality of simultaneously executed independent searches in one of a GPS mode and an IS-95 mode;

means for despreading received data for each independent search;

means for generating coherent accumulation results as a function of the despread data;

means for configuring a demodulator as a function of the coherent accumulation results in the GPS mode; and

means for, in the IS-95 mode,

computing energy values as a function of the coherent accumulation results,

generating non-coherent accumulation results as a function of the energy values,

identifying a plurality of energy peaks as a function of the non-coherent accumulation results,

sorting the plurality of energy peaks, and

configuring the demodulator as a function of the sorted energy peaks.

41. The apparatus of claim 40, wherein the received data comprises I and Q quadrature components of at least one of gain-adjusted I/Q data, center band I/Q data, lower band I/Q data, and higher band I/Q data.