Using a single FHT to decode access-based handoff probes from multiple users

• US 8,837,273 B2
• Filed: 08/17/2011
• Issued: 09/16/2014
• Est. Priority Date: 01/30/2007
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Khandekar, Aamod, Gorokhov, Alexei, Bhushan, Naga
• Primary Examiner(s): Nguyen, Brian D
• Assistant Examiner(s): NGUYEN, TOAN D
• Application Number:
  US13/212,114
• Publication Number:
  US 20120063293A1
• Time in Patent Office: 1,126 Days
• Field of Search: 370/208, 370/209, 370/328, 370/335, 370/338, 370/329, 455/436
• US Class Current: 370/209
• CPC Class Codes: H04B 2001/70935 using a bank of matched fileters, e.g. Fast Hadamard Transform
• CPC Class Codes: H04B 2201/70707 Efficiency-related aspects
• CPC Class Codes: H04J 13/0048 Walsh
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access

Abstract

A method includes scrambling a Walsh sequence with a random sequence to produce a scrambled Walsh sequence. The method also includes transmitting the scrambled Walsh sequence as an access-based handoff probe.

Claims

1. A method for using a single Fast Hadamard Transform for access-based handoff probes, the method comprising:

scrambling, at a first device, a first Walsh sequence with a random sequence to produce a first scrambled Walsh sequence, the random sequence to be used by a plurality of devices including the first device to scramble Walsh sequences during generation of handoff probes, wherein each of the Walsh sequences is decodable using a single Fast Hadamard Transform (FHT) including the random sequence; and

transmitting an access-based handoff probe that includes at least a portion of the first scrambled Walsh sequence.

2. The method of claim 1, further comprising receiving an access grant over a shared signaling medium access control protocol in response to the transmitted access-based handoff probe.

3. The method of claim 1, further comprising receiving an assignment of one or more sub-sequences of the first scrambled Walsh sequence at the first device, wherein the portion of the first scrambled Walsh sequence included in the access-based handoff probe corresponds to the one or more sub-sequences.

4. The method of claim 1, wherein the first scrambled Walsh sequence comprises 1,024 modulation symbols.

5. The method of claim 1, further comprising:

receiving the random sequence at the first device.

6. The method of claim 1, wherein the random sequence is to be used by the plurality of devices during a particular interval, and wherein a second random sequence is to be used by the plurality of devices during a second interval.

7. The method of claim 6, wherein the particular interval is 5 milliseconds.

8. The method of claim 1, wherein the random sequence is based on a transmission time of the access-based handoff probe, a maximum number of devices that can transmit access-based handoff probes at a particular time, or a combination thereof.

9. The method of claim 1, wherein the random sequence is based on a pilot level.

10. A wireless communications apparatus, the apparatus comprising:

a transmitter; and

a processor configured to;

scramble a first Walsh sequence with a random sequence to produce a first scrambled Walsh sequence, the random sequence to be used by a plurality of devices to scramble Walsh sequences during generation of handoff probes, wherein each of the Walsh sequences is decodable using a single Fast Hadamard Transform (FHT) including the random sequence; and

cause the transmitter to transmit an access-based handoff probe that includes at least a portion of the first scrambled Walsh sequence.

11. The wireless communications apparatus of claim 10, further comprising a receiver configured to:

receive the random sequence; and

receive an access grant over a shared signaling medium access control protocol in response to the access-based handoff probe.

12. The wireless communications apparatus of claim 10, further comprising receiving an assignment of one or more sub-sequences of the first scrambled Walsh sequence, wherein the portion of the first scrambled Walsh sequence included in the access-based handoff probe corresponds to the one or more sub-sequences.

13. The wireless communications apparatus of claim 10, wherein the first scrambled Walsh sequence comprises 1,024 modulation symbols.

14. The wireless communications apparatus of claim 10, further comprising a memory configured to store information related the first scrambled Walsh sequence and the access-based handoff probe.

15. A wireless communications apparatus that uses a single Fast Hadamard Transform for access-based handoff probes, the apparatus comprising:

means for scrambling a first Walsh sequence with a random sequence to produce a first scrambled Walsh sequence, the random sequence to be used by a plurality of devices to scramble Walsh sequences during generation of handoff probes, wherein each of the Walsh sequences is decodable using a single Fast Hadamard Transform (FHT) including the random sequence; and

means for transmitting an access-based handoff probe that includes at least a portion of the first scrambled Walsh sequence.

16. The wireless communications apparatus of claim 15, further comprising:

means for receiving the random sequence; and

means for receiving an access grant over a shared signaling medium access control protocol in response to the transmitted access-based handoff probe.

17. The wireless communications apparatus of claim 15, further comprising means for receiving an assignment of one or more sub-sequences of the first scrambled Walsh sequence, wherein the portion of the first scrambled Walsh sequence included in the access-based handoff probe corresponds to the one or more sub-sequences.

18. The wireless communications apparatus of claim 15, wherein the first scrambled Walsh sequence comprises 1,024 modulation symbols.

19. A non-transitory computer-readable medium comprising instructions that, when executed by a processor, cause the processor to:

scramble, at a first device, a first Walsh Sequence with a random sequence to produce a first scrambled Walsh sequence, the random sequence to be used by a plurality of devices including the first device to scramble Walsh sequences during generation of handoff probes, wherein each of the Walsh sequences is decodable using a single Fast Hadamard Transform (FHT) including the random sequence; and

cause a transmitter to transmit an access-based handoff probe that includes at least a portion of the first scrambled Walsh sequence.

20. The non-transitory computer-readable medium of claim 19, wherein the instructions further cause the processor to receive an assignment of one or more sub-sequences of the first scrambled Walsh sequence, wherein the portion of the first scrambled Walsh sequence included in the access-based handoff probe corresponds to the one or more sub-sequences.