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

• US 8,023,398 B2
• Filed: 01/29/2008
• Issued: 09/20/2011
• Est. Priority Date: 01/30/2007
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gorokhov, Alexei, Bhushan, Naga, Khandekar, Aamod
• Primary Examiner(s): Kizou; Hassan
• Assistant Examiner(s): Nguyen; Toan D
• Application Number:
  US12/021,961
• Publication Number:
  US 20080181096A1
• Time in Patent Office: 1,330 Days
• Field of Search: 370/209, 370/328, 370/329, 370/331, 370/335, 375/130, 455/427
• 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

Aspects describe a Fast Hadamard Transform that is common to multiple mobile devices. A scrambled sequence produced by the Fast Hadamard Transform can be utilized to decode access-based handoff probes from multiple terminals within a wireless communications system. A Walsh Sequence can be scrambled with a common random sequence to produce a scrambled sequence. At least a portion of the scrambled sequence is included in an access probe.

Claims

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

receiving access probes from two or more of a plurality of mobile devices, wherein the access probes are received substantially at the same time, wherein the access probes each include a scrambled Walsh sequence produced by scrambling a Walsh sequence with a random sequence, and wherein the random sequence is common to the two or more mobile devices; and

demodulating the scrambled Walsh Sequence of each access probe with a single Fast Hadamard Transform that comprises the random sequence.

2. The method of claim 1, further comprising:

selectively granting the two or more mobile device access to a sector based on the demodulation utilizing the random sequence.

3. The method of claim 2, wherein selectively granting the two or more mobile device access to the sector based on the demodulation comprises transmitting an Access Grant over a Shared Signaling Medium Access Control (MAC) Protocol.

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

5. A wireless communications apparatus, comprising:

a transmitter configured to;

send a random sequence to a mobile device of a plurality of mobile devices; and

send an assignment of one or more sub-sequences of a scrambled Walsh sequence to the mobile device, wherein the scrambled Walsh sequence is produced by scrambling a Walsh sequence with the random sequence, and wherein the random sequence is common to at least two of the plurality of mobile devices;

a receiver configured to receive from the mobile device the scrambled Walsh Sequence included in an access probe that is transmitted by the mobile device based on one or more of the assigned sub-sequences;

a processor configured to demodulate the scrambled Walsh Sequence with a single Fast Hadamard Transform that comprises the random sequence; and

a memory configured to store information related to analysis performed by the processor.

6. The apparatus of claim 5, wherein the processor is further configured to selectively grant the mobile device access to a sector based on the demodulation utilizing the random sequence.

7. The apparatus of claim 5, wherein the receiver is further configured to receive access probes from the at least two of the plurality of mobile devices and the processor is further configured to demodulate the scrambled Walsh Sequence included in the access probes with the single Fast Hadamard Transform that comprises the random sequence.

8. The apparatus of claim 5, wherein the transmitter is further configured to transmit an Access Grant over a Shared Signaling Medium Access Control (MAC) Protocol to grant the mobile device access to the sector.

9. The apparatus of claim 5, wherein the scrambled Walsh Sequence comprises 1,024 modulation symbols.

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

means for receiving access probes from two or more of a plurality of mobile devices, wherein the access probes are received substantially at the same time, wherein the access probes each include a scrambled Walsh sequence produced by scrambling a Walsh sequence with a random sequence, and wherein the random sequence is common to the two or more mobile devices; and

means for demodulating the scrambled Walsh Sequence of each access probe with a single Fast Hadamard Transform that comprises the random sequence.

11. The wireless communications apparatus of claim 10, further comprising:

means for selectively granting the two or more mobile devices access to a sector based on the demodulation.

12. The wireless communications apparatus of claim 11, wherein the means for selectively granting the two or more mobile devices access to the sector based on the demodulation comprises means for transmitting an Access Grant over a Shared Signaling Medium Access Control (MAC) Protocol.

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

14. In a wireless communication system, an apparatus comprising:

a transmitter configured to;

send a random sequence to a mobile device of a plurality of mobile devices; and

send an assignment of one or more sub-sequences of a scrambled Walsh sequence to the mobile device, wherein the scrambled Walsh sequence is produced by scrambling a Walsh sequence with the random sequence, and wherein the random sequence is common to at least two of the plurality of mobile devices;

a receiver configured to receive an access probe from the mobile device, wherein the access probe includes the scrambled Walsh Sequence that is transmitted by the mobile device based on one or more of the assigned sub-sequences; and

a processor configured to demodulate the scrambled Walsh Sequence with a single Fast Hadamard Transform that comprises the random sequence.

15. The wireless communication system of claim 14, wherein the receiver is further configured to receive access probes from two or more of the plurality of mobile devices and the processor is further configured to demodulate the scrambled Walsh Sequence included in the access probes with the single Fast Hadamard Transform that comprises the random sequence.

16. A non-transitory machine-readable medium having stored thereon machine-executable instructions for demodulating access probes, comprising:

instructions for receiving access probes from two or more of a plurality of mobile devices, wherein the access probes are received substantially at the same time, wherein the access probes each include a scrambled Walsh sequence produced by scrambling a Walsh sequence with a random sequence, and wherein the random sequence is common to the two or more mobile devices; and

instructions for demodulating the scrambled Walsh Sequence of each access probe with a single Fast Hadamard Transform that comprises the random sequence.