Method for performing a signal search in a wireless communication system

• US 5,881,058 A
• Filed: 11/25/1996
• Issued: 03/09/1999
• Est. Priority Date: 11/25/1996
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Chen, Jiangnan
• Primary Examiner(s): Pham, Chi H.
• Assistant Examiner(s): YAO, KWANG BIN
• Application Number:
  US08/758,269
• Time in Patent Office: 834 Days
• Field of Search: 370/319, 370/320, 370/328, 370/329, 370/331, 370/332, 370/334, 370/335, 370/342, 370/441, 370/479, 375/200, 375/206, 375/208, 375/209, 375/210, 375/346, 375/347, 375/348, 375/349, 455/63, 455/65, 455/562
• US Class Current: 370/335
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04B 1/7117 Selection, re-selection, allocation or re-allocation of paths to fingers, e.g. timing offset control of allocated fingers

Abstract

The method, which operates in a code division multiple access wireless communication system including a base site having a first and second antenna for receiving communication signals from a mobile unit and a base site receiver for demodulating the communications, includes receiving at a first antenna a first set of signals of the communication signals; processing, by a searcher, the first set of signals to produce an output indicative of a winning correlation energy and an associated pn-offset for at least one of the first set of signals; receiving at a second antenna a second set of signals of the communication signals; and using the output to coordinate demodulation of the at least one of the first set of signals of the communication signals, as a function of its pn-offset, while simultaneously processing, by the searcher, the second set of signals.

Claims

1. A method for performing a signal search in a code division multiple access wireless communication system, the method comprising the steps of:

receiving a communication signal at a first antenna to produce a first received signal;

inputting, at a first time offset, at least a first portion of the first received signal to a demodulator having a plurality of outputs to produce a first set of outputs;

selecting an output from the first set of outputs to produce a first selected output;

inputting, at a second time offset, at least a second portion of the first received signal to a demodulator to produce a second set of outputs;

selecting an output from the second set of outputs to produce a second selected output;

after selecting the first selected output and the second selected output, re-assigning a RAKE receiver finger for receiving the communication signal at the first antenna;

after re-assigning the RAKE receiver finger, receiving the communication signal at a second antenna to produce a second received signal;

inputting, at a first time offset, at least a first portion of the second received signal to the demodulator to produce a third set of outputs;

selecting an output from the third set of outputs to produce a third selected output;

inputting, at the second time offset, at least a second portion of the second received signal to the demodulator to produce a fourth set of outputs;

selecting an output from the fourth set of outputs to produce a forth selected output; and

after selecting the third selected output and the fourth selected output, re-assigning the RAKE receiver finger for receiving the communication signal at the second antenna.

2. The method according to claim 1, wherein the demodulator comprises a Fast Hadamard Transform.

3. The method according to claim 1, wherein the first received signal comprises a plurality of received symbols associated with a plurality of transmitted symbols.

4. The method according to claim 3, wherein at least a portion of the first received signal comprises one received symbol of the plurality of received symbols.

5. The method according to claim 4, wherein each of the plurality of outputs of the demodulator has a value associated therewith, the value representing the likelihood that the one received symbol corresponds to a transmitted symbol of the plurality of transmitted symbols.

6. The method according to claim 5, wherein the value associated with the first selected output has the greatest likelihood.

7. The method according to claim 1, wherein the first set of outputs comprises sixty-four outputs.

8. The method according to claim 1, wherein the first time offset and the second time offset are less than or equal to one Walsh chip apart.

9. The method according to claim 1, wherein the first and second antennae are associated with a first base station.

10. The method according to claim 9, wherein the first antenna is associated with a first sector of the first base station.

11. The method according to claim 9, wherein the second antenna is associated with a second sector of the first base station.

12. The method according to claim 1, wherein the first selected output is buffered for further processing.

13. The method of claim 1, further comprising the step of:

prior to re-assigning the RAKE receiver finger adjusting the times for receiving the communication signal, generating a signal indicating that a search has been completed.