Prioritizing pilot set searching for a CDMA telecommunications system

• US 6,154,455 A
• Filed: 12/24/1997
• Issued: 11/28/2000
• Est. Priority Date: 12/24/1997
• Status: Expired due to Fees

• Current Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Dowling, Joe, Gould, Adam, Yeoman, Darin, Mekkoth, Ajith
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): HOM, SHICK C
• Application Number:
  US08/998,171
• Time in Patent Office: 1,070 Days
• Field of Search: 370/241, 370/331, 370/332, 370/335, 370/342, 370/311, 370/320, 370/397, 370/399, 370/209, 370/208, 455/436, 455/437, 455/438, 455/439, 455/440, 455/442, 455/443, 455/67.1
• US Class Current: 370/342
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information

Abstract

This invention teaches methods, and circuits that operate in accordance with the methods, for improving the management and control of pilot channel sets for a CDMA mobile station. In one aspect a Priority Neighbor Search technique is provided, wherein a list of Priority Neighbor pilot channels is maintained and searched with a higher priority than the Neighbor Set pilot channels. In a further aspect this invention provides a Dropped Pilot Channel Search technique wherein a set is made of the last pilot channel or pilot channels dropped from the Active Set, wherein the dropped pilot channels are searched for some period of time with a higher priority than the Neighbor Set pilot channels. This invention also provides a High Priority Search Set feature which includes members of the Active Set, the Candidate Set, the Dropped Pilot Set, and the Priority Neighbor Set.

Claims

1. A method to perform a pilot channel search for use in a mobile station that maintains a Neighbor Set, Candidate Set, and Active Set of pilot channels, comprising steps of:

placing dropped pilot channels in a Dropped Pilot Channel Set;

placing strongest neighbor pilot channels in a Priority Neighbor Pilot Channel Set; and

searching the Dropped Pilot Channel Set and the Priority Neighbor Pilot Channel Set as separate pilot channel search sets.

2. The method as in claim 1, wherein the sets of pilot channels that are searched include the:

Active Set, Candidate Set, Dropped Pilot Channel Set, Priority Neighbor Set and one element of the Neighbor Set.

3. A method to perform a pilot channel search for use in a mobile station that maintains a Neighbor Set, Candidate Set, and Active Set of pilot channels, comprising steps of:

placing dropped pilot channels in a Dropped Pilot Channel Set;

placing strongest neighbor pilot channels in a Priority Neighbor Pilot Channel Set; and

forming a composite pilot channel set comprised of members of the Active Set, the Candidate Set, members of the Dropped Pilot Channel Set and the Priority Neighbor Pilot Channel Set in accordance with a selected ratio.

4. The method as in claim 3, wherein the step of forming said composite pilot channel set selects pilot channels in said selected ratio of one pilot channel from the Priority Neighbor Pilot Channel Set for every two pilot channels from the Dropped Pilot Channel Set.

5. The method as in claim 3, and further comprising steps of:

initializing a timer for each dropped pilot channel upon the inclusion of the pilot channel in the Dropped Pilot Channel Set; and

removing a pilot channel from the Dropped Pilot Channel Set upon expiration of the timer.

6. A mobile station comprising a controller for placing dropped pilot channels in a Dropped Pilot Channel Set, for placing strongest neighbor pilot channels in a Priority Neighbor Pilot Channel Set, and for forming a composite pilot channel set comprised of members of an Active Set, a Candidate Set, the Dropped Pilot Channel Set and the Priority Neighbor Pilot Channel Set, said controller selecting pilot channels in a ratio of x pilot channels from the Priority Neighbor Pilot Channel Set for every y pilot channels from the Dropped Pilot Channel Set.

7. The mobile station as in claim 6, wherein X=1 and y=2.

8. The mobile station as in claim 6, and further comprising a timer initialized for each dropped pilot channel upon the inclusion of the pilot channel in the Dropped Pilot Channel Set;

and a control means being responsive to an expiration of a timer for removing an associated pilot channel from the Dropped Pilot Channel Set.