System for automated determination of handoff neighbor list for cellular communication systems

• US 6,119,005 A
• Filed: 05/27/1998
• Issued: 09/12/2000
• Est. Priority Date: 05/27/1998
• Status: Expired due to Fees

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Smolik, Kenneth Frank
• Primary Examiner(s): CUMMING, WILLIAM D
• Application Number:
  US09/085,422
• Time in Patent Office: 839 Days
• Field of Search: 455/436, 455/423, 370/320, 370/331
• US Class Current: 455/436
• CPC Class Codes: H04B 7/2628 using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA] H04B7/2618 takes precedence
• CPC Class Codes: H04W 36/00835 Determination of neighbour cell lists
• CPC Class Codes: H04W 36/0085 Hand-off measurements

Abstract

The system for automated determination of handoff neighbor list uses the data collected from mobile subscriber units to automatically update the handoff neighbor list. The mobile subscriber unit produces Pilot Strength Measurement (PSM) data that is indicative of the relative signal strength measured at the mobile subscriber unit from a plurality of pilot channels. The mobile subscriber unit transmits this data, along with a list of viable pilot channel candidates as determined by the mobile subscriber unit, to the base station serving the existing call. The system for automated determination of handoff neighbor list maintains a data structure that stores data indicative of the number of instances that a pilot channel is recommended, the sum of power levels that were measured by the various mobile subscriber units for these instances. This data is processed to determine a metric for each data structure in the list, with the metric in the present embodiment being a function of the number of occurrences multiplied by a weighting factor summed with the sum of power levels.

Claims

1. In a cellular communication system, apparatus for updating a neighbor list that contains data indicative of a predetermined number of communication channels that can be used to handoff an existing cellular communication connection for a mobile subscriber unit, comprising:

means, responsive to pilot signal strength data received from mobile subscriber units for at least one of a plurality of pilot channels, for automatically updating at least one metric associated with said at least one of a plurality of pilot channels, comprising;

means, responsive to a mobile subscriber unit identifying a one of said plurality of pilot channels having a signal strength that exceeds a predetermined threshold, for generating data indicative of a number of instances that said one of said plurality of pilot channels has a signal strength that exceeds a predetermined threshold,

means, responsive to a mobile subscriber unit identifying a one of said plurality of pilot channels having a signal strength that exceeds a predetermined threshold, for generating data indicative of power level of said number of instances that said one of said plurality of pilot channels has a signal strength that exceeds a predetermined threshold,

means for generating a pilot channel metric for said one of said plurality of pilot channels using said data indicative of a number of instances and said data indicative of power level of said number of instances;

means for rank ordering said plurality of pilot channels as a function of said metrics; and

means for selecting at least one of said plurality of pilot channels for said neighbor list.

2. The cellular communication system of claim 1 wherein said means for rank ordering comprises:

means for ordering said plurality of pilot channels in order of a magnitude of said metrics.

3. The cellular communication system of claim 1 wherein said means for selecting comprises:

means for identifying a predetermined number of communication channels from said rank ordered list as candidates for said neighbor list; and

means for adding ones of said identified predetermined number of communication channels not presently in said neighbor list to said neighbor list.

4. The cellular communication system of claim 3 wherein said means for selecting further comprises:

means, responsive to a sum of existing members of said neighbor list and said added ones of said identified predetermined number of communication channels not presently in said neighbor list to said neighbor list, exceeding said predetermined number, for expunging sufficient ones of said members of said existing neighbor list to maintain said predetermined number as a number of members of said neighbor list.

5. In a cellular communication system, a method for updating a neighbor list that contains data indicative of a predetermined number of communication channels that can be used to handoff an existing cellular communication connection for a mobile subscriber unit, comprising the steps of:

automatically updating, in response to pilot signal strength data received from mobile subscriber units for at least one of a plurality of pilot channels, at least one metric associated with said at least one of a plurality of pilot channels, comprising;

generating, in response to a mobile subscriber unit identifying a one of said plurality of pilot channels having a signal strength that exceeds a predetermined threshold, data indicative of a number of instances that said one of said plurality of pilot channels has a signal strength that exceeds a predetermined threshold,

generating, in response to a mobile subscriber unit identifying a one of said plurality of pilot channels having a signal strength that exceeds a predetermined threshold, data indicative of power level of said number of instances that said one of said plurality of pilot channels has a signal strength that exceeds a predetermined threshold,

generating a pilot channel metric for said one of said plurality of pilot channels using said data indicative of a number of instances and said data indicative of power level of said number of instances;

rank ordering said plurality of pilot channels as a function of said metrics; and

selecting at least one of said plurality of pilot channels for said neighbor list.

6. The method of operating a cellular communication system of claim 5 wherein said step of rank ordering comprises:

ordering said plurality of pilot channels in order of a magnitude of said metrics.

7. The method of operating a cellular communication system of claim 5 wherein said step of selecting comprises:

identifying a predetermined number of communication channels from said rank ordered list as candidates for said neighbor list; and

adding ones of said identified predetermined number of communication channels not presently in said neighbor list to said neighbor list.

8. The method of operating a cellular communication system of claim 7 wherein said step of selecting further comprises:

expunging, in response to a sum of existing members of said neighbor list and said added ones of said identified predetermined number of communication channels not presently in said neighbor list to said neighbor list, exceeding said predetermined number, sufficient ones of said members of said existing neighbor list to maintain said predetermined number as a number of members of said neighbor list.

9. In a cellular communication system, apparatus for updating a neighbor list that contains data indicative of a predetermined number of communication channels that can be used to handoff an existing cellular communication connection for a mobile subscriber unit, comprising:

means, responsive to pilot signal strength data received from mobile subscriber units for a plurality of pilot channels indicative of signal, for generating data indicative of a number of instances that each of said plurality of pilot channels has a signal strength that exceeds a predetermined threshold;

means for generating data indicative of power level of said plurality of pilot channels that has a signal strength that exceeds a predetermined threshold;

means for automatically updating at least one metric associated with said plurality of pilot channels using said data indicative of a number of instances and said data indicative of power level;

means for rank ordering said plurality of pilot channels as a function of said metrics; and

means for selecting at least one of said plurality of pilot channels for said neighbor list.

10. The cellular communication system of claim 9 wherein said means for rank ordering comprises:

means for ordering said plurality of pilot channels in order of a magnitude of said metrics.

11. The cellular communication system of claim 9 wherein said means for selecting comprises:

means for identifying a predetermined number of communication channels from said rank ordered list as candidates for said neighbor list; and

means for adding ones of said identified predetermined number of communication channels not presently in said neighbor list to said neighbor list.

12. The cellular communication system of claim 11 wherein said means for selecting further comprises:

means, responsive to a sum of existing members of said neighbor list and said added ones of said identified predetermined number of communication channels not presently in said neighbor list to said neighbor list, exceeding said predetermined number, for expunging sufficient ones of said members of said existing neighbor list to maintain said predetermined number as a number of members of said neighbor list.

13. In a cellular communication system, a method for updating a neighbor list that contains data indicative of a predetermined number of communication channels that can be used to handoff an existing cellular communication connection for a mobile subscriber unit, comprising the steps of:

generating, in response to pilot signal strength data received from mobile subscriber units for a plurality of pilot channels indicative of signal, data indicative of a number of instances that each of said plurality of pilot channels has a signal strength that exceeds a predetermined threshold;

generating data indicative of power level of said plurality of pilot channels that has a signal strength that exceeds a predetermined threshold;

automatically updating at least one metric associated with said plurality of pilot channels using said data indicative of a number of instances and said data indicative of power level;

ordering said plurality of pilot channels as a function of said metrics; and

selecting at least one of said plurality of pilot channels for said neighbor list.

14. The method of operating a cellular communication system of claim 13 wherein said ste of rank ordering comprises:

ordering said plurality of pilot channels in order of a magnitude of said metrics.

15. The method of operating a cellular communication system of claim 13 wherein said step of selecting comprises:

identifying a predetermined number of communication channels from said rank ordered list as candidates for said neighbor list; and

adding ones of said identified predetermined number of communication channels not presently in said neighbor list to said neighbor list.

16. The method of operating a cellular communication system of claim 15 wherein said step of selecting further comprises:

expunging, in response to a sum of existing members of said neighbor list and said added ones of said identified predetermined number of communication channels not presently in said neighbor list to said neighbor list, exceeding said predetermined number, sufficient ones of said members of said existing neighbor list to maintain said predetermined number as a number of members of said neighbor list.