Mobile switching centre and method for handling a dropped connection between a mobile station and a basestation transceiver

• US 6,246,872 B1
• Filed: 05/06/1998
• Issued: 06/12/2001
• Est. Priority Date: 05/06/1998
• Status: Active Grant

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Lewis, Len, Lee, Henry
• Primary Examiner(s): LEGREE, TRACY MICHELLE
• Application Number:
  US09/073,442
• Time in Patent Office: 1,133 Days
• Field of Search: 455/423, 455/421, 455/426, 455/437-446, 455/458, 455/459, 455/432, 455/433, 455/517, 455/414, 370/331, 370/312, 370/338
• US Class Current: 455/414.1
• CPC Class Codes: H04W 4/00 Services specially adapted for wireless communication networks; Facilities therefor
• CPC Class Codes: H04W 76/10 Connection setup

Abstract

A system and method for recovering from a lost connection between a mobile station and a mobile communications system after a traffic channel has been successfully assigned are provided. After the connection is lost, rather than dropping the call altogether, the party on the other end of the call is connected to an announcement. While the announcement is playing, the system pages the mobile station in an effort to re-locate it and re-establish a traffic channel. When a traffic channel is successfully re-established, the call is connected. The connection may be lost during handoff, conversation (normal use), mobile termination or mobile origination for example.

Claims

1. In a communications system, wherein a call connection between a first mobile terminal and a connection entity comprises a first connection over an assigned traffic channel between the mobile terminal and a mobile switching centre and a second connection between the mobile switching centre and the connection entity, wherein said first connection may be lost after successfully assigning said traffic channel, a method of recovering from such a lost first connection comprising the steps of:

a) maintaining said second connection;

b) paging the first mobile terminal to determine its location;

c) establishing a new first connection between the mobile terminal and the mobile switching centre;

d) after establishing a new first connection between the mobile terminal and the mobile switching centre, alerting the mobile terminal with a special ringing tone and/or message text; and

e) bridging the second connection with said new first connection thereby re-connecting the call after the call is answered by the mobile terminal;

wherein said first connection was lost during a handoff;

wherein in said step of paging the mobile terminal, the mobile terminal is paged in a plurality of cells defined by a target cell list generated during handoff.

2. A mobile switching centre for use in a communications system, wherein a call connection between a first mobile terminal and a connection entity comprises a first connection over an assigned traffic channel between the mobile terminal and the mobile switching centre and a second connection between the mobile switching centre and the connection entity;

the mobile switching centre comprising;

a handoff mechanism for coordinating a handoff to a target cell within a list of target cells identified as being suitable candidates for handoff;

a connection recovery mechanism for recovering said first connection after it is lost after said traffic channel has been successfully assigned during handoff, the connection recovery mechanism comprising;

a) a connection holding mechanism for maintaining said second connection after said first connection is lost;

b) a paging mechanism for paging the first mobile terminal to determine its location in cells of said list of target cells;

c) connection establishment circuitry for coordinating the establishment of a new first connection between the mobile terminal and the mobile switching centre;

d) means for alerting the mobile terminal with a special ringing tone and/or message text when a new second connection is ready to be established; and

e) connection bridging circuitry for bridging the second connection with said new first connection after the call is answered by the mobile terminal thereby re-connecting the call.