Method of performing handoff in a cellular communication system

• US 5,432,843 A
• Filed: 08/02/1993
• Issued: 07/11/1995
• Est. Priority Date: 08/02/1993
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Bonta, Jeffrey D.
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Bost, Dwayne D.
• Application Number:
  US08/100,230
• Time in Patent Office: 708 Days
• Field of Search: 379/59, 379/60, 455/33.1, 455/33.2
• US Class Current: 455/438
• CPC Class Codes: H04W 36/0055 Transmission or use of information for re-establishing the radio link
• CPC Class Codes: H04W 36/00835 Determination of neighbour cell lists
• CPC Class Codes: H04W 36/0085 Hand-off measurements
• CPC Class Codes: H04W 36/12 Reselecting a serving backbone network switching or routing node

Abstract

The method consists of analyzing a handoff request received from a source base station at a source base site controller (BSC). If the handoff request contains a preferred base site list (is from a MAHO environment) the request is forwarded to the mobile switching center. If the handoff request does not contain the preferred list, the BSC generates a candidate list and transmits measurement messages to each candidate base site. The candidate base sites take measurements and reply to the BSC. The BSC uses the replies to generate a preferred base site list which is forwarded to the MSC. When the MSC receives a preferred base site list, it selects a handoff base site and executes the handoff.

Claims

1. A method of performing a handoff in a cellular communication system, said method comprising the steps of:

sending a handoff request from a source base station to a source base station controller;

generating, in said source base station controller, a candidate list of a plurality of candidate base stations;

transmitting a measurement request from said source base station controller to at least one of said plurality of candidate base stations on said candidate list;

measuring a signal from a mobile station at said at least one candidate base station;

reporting said measurement to said source base station controller;

generating a preferred list containing said measurement from said at least one candidate base station;

transmitting said preferred list from said source base station controller to a source mobile switching center;

selecting a handoff base station from said preferred list; and

directing a handoff of said mobile station to said handoff base station.

2. The method of claim 1 wherein said measurement request is a signal strength measurement request.

3. The method of claim 1 wherein said measurement request is one of a energy per chip per total noise, a bit error rate, a frame erasure rate, and a word error rate.

4. The method of claim 1 further comprising the step of:

analyzing said handoff request received by said source base station controller to determine if said handoff request contains a preferred list; and

transmitting said handoff request to said source mobile switching center if said handoff request contains said preferred list.

5. A method of performing a handoff in a cellular communication system, said method comprising the steps of:

sending a handoff request from a source base station to a source base station controller;

analyzing said handoff request received by said source base station controller to determine if said handoff request contains a preferred list of a plurality of candidate base stations;

transmitting said handoff request to a source mobile switching center if said handoff request contains said preferred list;

generating, in said source base station controller, a candidate list of a plurality of candidate base stations if said handoff request does not contain said preferred list;

transmitting a measurement request from said source base station controller to at least one of said plurality of candidate base stations on said candidate list;

measuring a signal from a mobile station at said at least one candidate base station;

reporting said measurement to said source base station controller;

generating a preferred list containing said measurement from said at least one candidate base station;

transmitting said preferred list from said source base station controller to a source mobile switching center;

selecting a handoff base station from said preferred list; and

directing a handoff of said mobile station to said handoff base station.

6. The method of claim 5 wherein said measurement request is a signal strength measurement request.

7. The method of claim 5 wherein said measurement request is one of a bit error rate and a word error rate.

8. A method of performing a handoff in a cellular communication system, said method comprising the steps of:

sending a handoff request from a source base station to a source base station controller;

generating, in said source base station controller, a candidate list of a plurality of candidate base stations if said source base station is an analog base station;

transmitting said handoff request to a source mobile switching center if said source base station is a type base station other than said analog base station;

transmitting a measurement request from said source base station controller to at least one of said plurality of candidate base stations on said candidate list;

measuring a signal from a mobile station at said at least one candidate base station;

reporting said measurement to said source base station controller;

generating a preferred list containing said measurement from said at least one candidate base station;

transmitting said preferred list from said source base station controller to a source mobile switching center;

selecting a handoff base station from said preferred list; and

directing a handoff of said mobile station to said handoff base station.