SIGNAL ACQUISITION IN A WIRELESS COMMUNICATION SYSTEM

• US 20080285526A1
• Filed: 05/21/2007
• Published: 11/20/2008
• Est. Priority Date: 05/22/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gorokhov, Alexei, Palanki, Ravi, Khandekar, Aamod
• Granted Patent: US 8,738,056 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver

Abstract

Systems and methodologies are described that generate pilots for signal acquisition in a wireless communication system based on time domain sequences. The pilots may be generated by a base station and transmitted in a pilot field to one or more access terminals to aid in signal acquisition at each of the access terminals. One of the pilots may be common to all access points in the wireless communication system, thereby allowing an access terminal to obtain a timing estimate for the system while minimizing the effects of interference variations between base stations. Further, one or more generated pilots may be unique to each access point in order to allow each respective access point to be identified by its generated pilots.

Claims

1. A method for generating and transmitting acquisition pilots in a wireless communication system, comprising:

generating a first acquisition pilot based at least in part on a first time domain pilot sequence, the first time domain pilot sequence is common to the wireless communication system;

generating a second acquisition pilot based at least in part on a second time domain pilot sequence, the second time domain pilot sequence is common to a subset of the wireless communication system that includes less than all of the wireless communication system;

generating a third acquisition pilot based at least in part on a third time domain pilot sequence, the third time domain pilot sequence is common to a subset of the wireless communication system that includes less than all of the wireless communication system; and

transmitting the first, second, and third time domain pilot sequences to one or more access terminals in a pilot field.

2. The method of claim 1, wherein the first acquisition pilot is periodic in time.

3. The method of claim 2, wherein each period of the first acquisition pilot comprises one or more of a pseudo-noise (PN) sequence, a generalized chirp-like (GCL) sequence, and a Chu sequence.

4. The method of claim 2, wherein the first and second acquisition pilots have an equal predetermined length and the third acquisition pilot has a predetermined length that is substantially equal to one period of the first acquisition pilot in time.

5. The method of claim 1, wherein the generating the second acquisition pilot includes generating the second acquisition pilot based at least in part on an identifier for an entity generating the acquisition pilots, and the generating the third acquisition pilot includes generating the third acquisition pilot based at least in part on the identifier for the entity generating the acquisition pilots.

6. The method of claim 5, wherein the identifier for the entity generating the acquisition pilots comprises a plurality of bits, the second acquisition pilot is generated based on a portion of the plurality of bits of the identifier, and the third acquisition pilot is generated based on all of the plurality of bits of the identifier.

7. The method of claim 1, wherein the second acquisition pilot and the third acquisition pilot are Walsh sequences.

8. The method of claim 7, wherein a scrambling code is applied to the second acquisition pilot and the third acquisition pilot, and the scrambling code is independent of an entity generating the acquisition pilots.

9. The method of claim 1, wherein the pilot field is transmitted in a superframe preamble.

10. A wireless communications apparatus, comprising:

a memory that stores data relating to a first time domain pilot sequence, a second time domain pilot sequence, and a third time domain pilot sequence, wherein the first time domain pilot sequence is common to a system in which the wireless communications apparatus operates and the second time domain pilot sequence and the third time domain pilot sequence are common to a subset of the system that includes less than all of the system; and

a processor configured to generate a first acquisition pilot from the first time domain pilot sequence, to generate a second acquisition pilot from the second time domain pilot sequence, to generate a third acquisition pilot from the third time domain pilot sequence, and to transmit the three generated acquisition pilots to a terminal.

11. The wireless communications apparatus of claim 10, wherein the processor is further configured to generate the first acquisition pilot to provide timing information for the network in which the wireless communications apparatus operates.

12. The wireless communications apparatus of claim 10, wherein the first acquisition pilot is periodic in time and has a length equal to a predetermined number of periods.

13. The wireless communications apparatus of claim 10, wherein each period of the first acquisition pilot is a GCL sequence.

14. The wireless communications apparatus of claim 10, wherein the memory further stores data relating to an identifier for the wireless communications apparatus, and the processor is further configured to generate the second acquisition pilot and the third acquisition pilot based on the identifier to provide one or more of identification information and timing information for the wireless communications apparatus.

15. The wireless communications apparatus of claim 14, wherein the processor is further configured to generate the second acquisition pilot and the third acquisition pilot to provide hierarchical search information that facilitates identification of the wireless communications apparatus.

16. The wireless communications apparatus of claim 14, wherein the second acquisition pilot and the third acquisition pilot are Walsh sequences.

17. The wireless communications apparatus of claim 16, wherein the memory further stores data relating to a scrambling code that is independent of the identifier for the wireless communications apparatus and the processor is further configured to generate the second acquisition pilot and the third acquisition pilot based on the scrambling code.

18. An apparatus that facilitates the generation and transmission of pilot sequences in a wireless communication network, comprising:

means for generating a first time domain pilot sequence that is common to the wireless communication network;

means for generating a second time domain pilot sequence that is common to less than all of the wireless communication network;

means for generating a third domain pilot sequence that is common to less than all of the wireless communication network; and

means for transmitting the generated time domain pilot sequences to one or more users.

19. The apparatus of claim 18, wherein the first time domain pilot sequence is periodic in time.

20. The apparatus of claim 18, wherein one or more of the second time domain pilot sequence and the third time domain pilot sequence identify the apparatus.

21. A computer-readable medium having stored thereon computer-executable instructions for generating and transmitting information for signal acquisition in a wireless communication environment, the instructions comprising:

generating a first acquisition pilot, a second acquisition pilot, and a third acquisition pilot based on one or more sequences in the time domain, wherein at least one sequence on which the first acquisition pilot is based is common to the wireless communication environment; and

transmitting the generated acquisition pilots to a terminal.

22. The computer-readable medium of claim 21, wherein the first acquisition pilot comprises a periodic sequence.

23. The computer-readable medium of claim 21, wherein the second acquisition pilot and the third acquisition pilot comprise identification information for an entity generating the acquisition pilots.

24. A processor that executes computer-executable instructions for providing acquisition information in a wireless communication network, the instructions comprising:

generating a first acquisition pilot based at least in part on a first time domain sequence;

generating a second acquisition pilot based at least in part on a second time domain sequence and an identifier for an entity generating the acquisition pilots; and

generating a third acquisition pilot based at least in part on a third time domain sequence and the identifier for the entity generating the acquisition pilots.

25. The processor of claim 24, the instructions further comprising transmitting the first, second, and third acquisition pilots to one or more access terminals in a pilot field.

26. A method for signal acquisition in a wireless communication system, comprising:

detecting a first time domain acquisition pilot, a second time domain acquisition pilot, and a third time domain acquisition pilot;

identifying an access point for communication based at least in part on the detected time domain acquisition pilots; and

synchronizing with the identified access point for communication based at least in part on the detected time domain acquisition pilots.

27. The method of claim 26, wherein the detecting includes:

receiving one or more signals;

correlating with respect to the one or more signals; and

determining whether the one or more signals comprise one or more time domain acquisition pilots based on the correlation.

28. The method of claim 27, wherein the correlating with respect to the one or more signals includes correlating with respect to the one or more signals based on a delayed correlation algorithm.

29. The method of claim 27, wherein the second time domain acquisition pilot and the third time domain acquisition pilot are Walsh sequences, and the correlating with respect to the one or more signals includes correlating with respect to the one or more signals simultaneously based at least in part on a Walsh-Hadamard transform.

30. The method of claim 26, wherein the second time domain acquisition pilot and the third time domain acquisition pilot are based at least in part on an identifier for the access point for communication, and identifying an access point for communication includes identifying the access point for communication based on the identifier.

31. The method of claim 30, wherein the second time domain acquisition pilot is based on a portion of the identifier, the third time domain acquisition pilot is based on all or substantially all of the identifier, and the identifying an access point for communication includes conducting a hierarchical search for the access point for communication.

32. The method of claim 26, wherein the synchronizing with the identified access point includes:

determining timing of the wireless communication system based on the first time domain acquisition pilot; and

determining timing of the identified access point based on the second time domain acquisition pilot and the third time domain acquisition pilot.

33. A wireless communications apparatus, comprising:

a memory; and

a processor coupled to the memory configured to detect a pilot field comprising three time domain acquisition pilots and to identify and synchronize with a base station for communication based at least in part on the pilot field.

34. The wireless communications apparatus of claim 33, wherein the time domain acquisition pilots in the pilot field provide hierarchical search information and the processor is further configured to identify the base station for communication at least in part by searching for the base station for communication using the hierarchical search information.

35. The wireless communications apparatus of claim 33, wherein one or more of the time domain acquisition pilots in the pilot field are Walsh sequences and the processor is further configured to detect the pilot field at least in part by using a Walsh-Hadamard transform.

36. An apparatus that facilitates signal acquisition in a wireless communication network, comprising:

means for detecting a first acquisition pilot based at least in part on a first time domain pilot sequence;

means for detecting a second acquisition pilot based at least in part on a second time domain pilot sequence;

means for detecting a third acquisition pilot based at least in part on a third time domain pilot sequence;

means for identifying an entity corresponding to the detected acquisition pilots; and

means for synchronizing with the entity corresponding to the detected acquisition pilots.

37. A computer-readable medium having stored thereon computer-executable instructions for acquiring information for communication in a wireless communication environment, the instructions comprising:

detecting a first acquisition pilot, a second acquisition pilot, and a third acquisition pilot, each acquisition pilot based on one or more sequences in the time domain;

identifying an access point for communication based on the detected acquisition pilots; and

acquiring timing information corresponding to the identified access point based on the detected acquisition pilots.

38. The computer-readable medium of claim 37, wherein the detecting includes:

attempting to detect a first acquisition pilot;

if the first acquisition pilot is detected, attempting to detect a second acquisition pilot; and

if the second acquisition pilot is detected, attempting to detect a third acquisition pilot.

39. The computer-readable medium of claim 37, wherein the acquiring timing information includes:

acquiring global timing information for the wireless communication environment; and

acquiring fine timing information for the identified access point.

40. A processor that executes computer-executable instructions for acquiring a signal for communication in a wireless communication system, the instructions comprising:

detecting a pilot field comprising a first time domain pilot sequence, a second time domain pilot sequence, and a third time domain pilot sequence, wherein the first time domain pilot sequence is common to the wireless communication system; and

establishing a connection for communication with a base station based at least in part on the detected pilot field.

41. The processor of claim 40, wherein the establishing a connection for communication includes identifying the base station and synchronizing with the base station.