Method and system for intelligent determination of pseudonoise (PN) offsets

• US 9,002,359 B1
• Filed: 04/12/2012
• Issued: 04/07/2015
• Est. Priority Date: 04/12/2012
• Status: Expired due to Fees

• Current Assignee: Sprint Spectrum LLC (Deutsche Telekom AG)
• Original Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Inventors: Vargantwar, Sachin R., Gauba, Maneesh, Shah, Maulik K., Goyal, Anoop K.
• Primary Examiner(s): Magloire, Vladimir
• Assistant Examiner(s): DONADO, FRANK E
• Application Number:
  US13/445,280
• Time in Patent Office: 1,090 Days
• Field of Search: None
• US Class Current: 455/436
• CPC Class Codes: H04W 36/0044 of quality context information
• CPC Class Codes: H04W 36/0061 of neighbour cell information
• CPC Class Codes: H04W 36/0085 Hand-off measurements

Abstract

A mobile station measures a pseudonoise (PN) offset and a signal strength of a spread spectrum signal transmitted by a given sector of a spread spectrum communication system. The measured PN offset differs from a nominal PN offset of the given sector. The mobile station transmits a measurement message that includes the measured PN offset and the measured signal strength. The spread spectrum communication system receives the measurement message and determines a location associated with the mobile station (e.g., based on location coordinates included in the measurement message). The spread spectrum communication system determines the nominal PN offset of the given sector based on the measured PN offset and the location associated with the mobile station. If the given sector is a valid handoff destination, the spread spectrum communication system transmits to the mobile station a handoff instruction that identifies the given sector by the measured PN offset.

Claims

1. A method for a spread spectrum communication system, wherein said spread spectrum communication system comprises a plurality of sectors in which each sector is associated with a respective nominal pseudonoise (PN) offset, said method comprising:

said spread spectrum communication system receiving a measurement message from a mobile station, wherein said measurement message includes a measured PN offset that said mobile station measured for a given sector in said plurality of sectors and further includes a signal strength that said mobile station measured for said given sector, wherein said measured PN offset differs from a nominal PN offset of said given sector;

said spread spectrum communication system determining a location associated with said mobile station;

said spread spectrum communication system determining said nominal PN offset of said given sector based on said measured PN offset and said location associated with said mobile station by a process comprising said spread spectrum communication system determining that a distance between said location associated with said mobile station and a location associated with said nominal PN offset at least partially accounts for a phase difference between said nominal PN offset and said measured PN offset;

said spread spectrum communication system determining whether said given sector is a valid handoff destination based on the difference between the measured PN offset for the given sector and the nominal PN offset and said spread spectrum communication system determining whether said nominal PN offset of said given sector was in a neighbor list transmitted to said mobile station; and

in response to a determination that said given sector is a valid handoff destination, said spread spectrum communication system transmitting to said mobile station a handoff instruction that identifies said given sector by said measured PN offset.

2. The method of claim 1, wherein said location associated with said nominal PN offset is a location of a base transceiver station (BTS) that transmits spread spectrum signals with said nominal PN offset.

3. The method of claim 1, wherein said spread spectrum communication system determining a location associated with said mobile station comprises said spread spectrum communication system receiving location coordinates from said mobile station.

4. The method of claim 3, wherein said measurement message includes said location coordinates.

5. The method of claim 1, wherein said spread spectrum communication system determining a location associated with said mobile station comprises:

determining a primary sector serving said mobile station; and

determining a distance between said mobile station and a primary base transceiver station (BTS) that defines said primary sector.

6. The method of claim 5, wherein determining said distance between said mobile station and said primary BTS comprises measuring a round-trip delay for spread spectrum signals transmitted between said mobile station and said primary BTS.

7. The method of claim 1, wherein said spread spectrum communication system determining whether said given sector is a valid handoff destination comprises said spread spectrum communication system determining whether said nominal PN offset of said given sector was in a neighbor list transmitted to said mobile station.

8. The method of claim 1, wherein said measurement message is a Pilot Strength Measurement Message (PSMM).

9. The method of claim 1, wherein said handoff instruction is a Handoff Direction Message (HDM).

10. A spread spectrum communication system, comprising:

a plurality of base transceiver stations (BTSs) that are configured to provide wireless coverage in a plurality of sectors, wherein each sector is associated with a respective nominal pseudonoise (PN) offset;

a controller for controlling said plurality of BTSs, wherein said controller is configured to;

(a) receive a measurement message from a mobile station, wherein said measurement message includes a measured PN offset that said mobile station measured for a given sector in said plurality of sectors and further includes a signal strength that said mobile station measured for said given sector, wherein said measured PN offset differs from a nominal PN offset of said given sector;

(b) determine a location associated with said mobile station;

(c) determine said nominal PN offset of said given sector based on said measured PN offset and said location associated with said mobile station by a process comprising said controller determining that a distance between said location associated with said mobile station and a location associated with said nominal PN offset at least partially accounts for a phase difference between said nominal PN offset and said measured PN offset;

(d) determine whether said given sector is a valid handoff destination based on the difference between the measured PN offset for the given sector and the nominal PN offset and said spread spectrum communication system determining whether said nominal PN offset of said given sector was in a neighbor list transmitted to said mobile station; and

(e) in response to a determination that said given sector is a valid handoff destination, generate a handoff instruction for said mobile station, wherein said handoff instruction identifies said given sector by said measured PN offset.

11. The spread spectrum communication system of claim 10, wherein said controller is configured to determine said location associated with said mobile station based on location coordinates of said mobile station included in said measurement message.

12. The spread spectrum communication system of claim 10, wherein said controller is configured to determine said location associated with said mobile station based on one or more round-trip delay measurements obtained by a BTS serving said mobile station.

13. The spread spectrum communication system of claim 10, wherein said controller comprises a base station controller (BSC).