Method and system for management of neighbor scanning

• US 9,369,952 B1
• Filed: 12/30/2014
• Issued: 06/14/2016
• Est. Priority Date: 09/14/2010
• 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., Sigg, Jason P.
• Primary Examiner(s): Renner, Brandon
• Assistant Examiner(s): Mensah, Prince A
• Application Number:
  US14/586,709
• Time in Patent Office: 532 Days
• US Class Current: 1/1
• CPC Class Codes: H04W 36/0016 Hand-off preparation specially adapted for end-to-end data sessions
• CPC Class Codes: H04W 36/0061 of neighbour cell information
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information

Abstract

Disclosed herein is a method and corresponding system for management of neighbor scanning in a cellular wireless communication system. A radio access network (RAN) sends, and a mobile station receives, a neighbor list update message (NLUM) containing a plurality of different neighbor lists. The mobile station then selects one of the neighbor lists based on a determined first rank-ordering of its active set members. Once the mobile station selects one of the neighbor lists, the mobile station scans the neighbors listed in the selected neighbor list in accordance with the selected neighbor list. If the mobile station detects a change in rank-ordering from the determined first rank-ordering to another rank-ordering, the mobile station may select and transition to another one of the neighbor lists and may begin to scan the neighbors listed in the selected other neighbor list in accordance with the selected other neighbor list.

Claims

1. In a mobile station operative to maintain in data storage an active set specifying a plurality of wireless coverage areas (“

active set members”

) in which the mobile station is currently set to communicate, a method comprising;

the mobile station wirelessly receiving a neighbor list update message (NLUM) that contains a plurality of different neighbor lists, each of the plurality of neighbor lists listing respective neighbors and defining a respective priority scanning order of the neighbors listed in the neighbor list, wherein the neighbor lists of the plurality contained in the received NLUM all comprise a same set of neighbors as each other but all list neighbors in a different respective priority scanning order than each other;

the mobile station monitoring signal strength of each of the mobile station'"'"'s active set members;

the mobile station determining a first rank-ordering of the mobile station'"'"'s active set members based on the relative signal strength of the active set members;

based on the determined first rank-ordering of the mobile station'"'"'s active set members, the mobile station selecting one of the plurality of neighbor lists; and

the mobile station scanning the neighbors listed in the selected neighbor list, wherein the scanning is carried out according to the priority scanning order of the selected neighbor list.

2. The method of claim 1, further comprising:

the mobile station detecting a change in the rank-ordering from the determined first rank-ordering to another rank-ordering;

based on the other rank-ordering, the mobile station selecting another one of the neighbor lists; and

the mobile station scanning the neighbors listed in the selected other neighbor list in accordance with the priority scanning order of the selected other neighbor list.

3. The method of claim 1, wherein each of the neighbors comprises a wireless coverage area neighboring one of the mobile station'"'"'s active set members, and wherein the neighbors of one of the neighbor lists differ by at least one neighbor from the neighbors of another one of the neighbor lists.

4. The method of claim 1, wherein each of the neighbors comprises a wireless coverage area neighboring one of the mobile station'"'"'s active set members.

5. The method of claim 1, wherein each neighbor list lists a respective number of neighbors per active set member such that the respective number of neighbors for each active set member is different.

6. The method of claim 5, wherein each neighbor list defines a different difference between the respective numbers of neighbors per active set member.

7. The method of claim 1, wherein wirelessly receiving the NLUM comprises wirelessly receiving the NLUM from a radio access network serving the mobile station.

8. The method of claim 1, wherein each of the neighbors is a Code Division Multiple Access (CDMA) sector operating on a respective pseudo-noise (PN) offset, and wherein each neighbor list identifies neighbors at least in part by PN offset.

9. The method of claim 1, wherein the signal strength is a signal-to-noise ratio.

10. The method of claim 1, further comprising carrying out the method while the mobile station is actively engaged in a call.

11. The method of claim 1, wherein each of the plurality of neighbor lists is optimized for a different respective rank-ordering of the mobile station'"'"'s active set members.

12. In a radio access network (RAN) serving a mobile station, wherein the mobile station maintains in data storage an active set specifying a plurality of wireless coverage areas (“

active set members”

) in which the mobile station is currently set to communicate, and wherein the mobile station regularly monitors the respective signal strength of each of the active set members and determines a rank-ordering of the active set members based on their relative signal strength, a method comprising;

the RAN detecting a trigger for updating neighbor list data in the mobile station; and

in response to detecting the trigger, the RAN sending to the mobile station a neighbor list update message (NLUM) containing a plurality of different neighbor lists, wherein each neighbor list is optimized for a different respective rank-ordering of the mobile station'"'"'s active set members and defines a different respective priority scanning order of neighbors listed in the neighbor list, wherein the neighbor lists of the plurality contained in the sent NLUM all comprise a same set of neighbors as each other but all list neighbors in a different respective priority scanning order than each other.

13. The method of claim 12, wherein the trigger comprises the RAN receiving a power strength management message (PSMM) from the mobile station.

14. The method of claim 13, wherein the PSMM indicates (i) the respective signal strengths of the mobile station'"'"'s active set members and (ii) a signal strength of at least one wireless coverage area that is greater than at least one of the respective signal strengths of the mobile station'"'"'s active set members.

15. The method of claim 12, further comprising:

the RAN receiving a power strength management message (PSMM) from the mobile station; and

in response to receiving the PSMM, the RAN sending a handoff direction message (HDM) to the mobile station granting handoff, wherein the NLUM is sent to the mobile station in the HDM.

16. The method of claim 12, wherein each of the neighbors is a Code Division Multiple Access (CDMA) sector operating on a respective pseudo-noise (PN) offset, and wherein each neighbor list identifies neighbors at least in part by PN offset.

17. A mobile station comprising:

a wireless communication interface for communicating wirelessly with a radio access network (RAN), including wirelessly receiving a neighbor list update message containing a plurality of different neighbor lists, each of the plurality of neighbor lists listing respective neighbors and defining a respective priority scanning order of the neighbors listed in the neighbor list, wherein the neighbor lists of the plurality contained in the received neighbor list update message all comprise a same set of neighbors as each other but all list neighbors in a different respective priority scanning order than each other;

a processor;

data storage;

active set data stored in the data storage defining a plurality of wireless coverage areas (“

active set members”

) in which the mobile station is currently set to communicate; and

program logic stored in the data storage and executable by the processor for (i) monitoring signal strength of each of the active set members (ii) determining a first rank-ordering of the active set members based on their relative signal strength, (iii) selecting one of the neighbor lists based on the determined first rank-ordering, and (iv) scanning the neighbors listed in the selected neighbor list for handoff, wherein the scanning is carried out according to the priority scanning order of the selected neighbor list.

18. The mobile station of claim 17, wherein the program logic is further executable for selecting another one of the neighbor lists in response to the mobile station detecting a change in the rank-ordering from the determined first rank-ordering to another rank-ordering.

19. The mobile station of claim 17, wherein each of the neighbors is a Code Division Multiple Access (CDMA) sector operating on a respective pseudo-noise (PN) offset, and wherein each neighbor list identifies neighbors at least in part by PN offset.

20. The method of claim 17, wherein each of the neighbors comprises a wireless coverage area neighboring one of the mobile station'"'"'s active set members.