Method for triggering inter-RAT idle handoff
AssigneeAlcatel Lucent
InventorsChristopher Francis Mooney, David Albert Rossetti, Jialin Zou
Life of this patent
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Abstract
A method for inter-RAT idle handoff is provided by transmitting a handoff initiation signal from a cell associated with a carrier for a first Radio Access Technology (RAT) area, the cell being located in an overlap coverage area with a second RAT area and adjacent to the second RAT area. Spatial hysteresis is provided by the new triggering method to eliminate the ping-pong issue when a mobile move along the border area. The invention also reduces network resource consumption due to ping-ponging.
Claims16
A method of triggering idle hand-offs at Radio Access Technology (RAT) borders in a wireless cellular system, comprising:
- sending an idle hand-off indication signal to an access terminal attached to a first carrier of a first RAT type when the access terminal moves into an edge cell of a border coverage area that is covered by the first carrier and a second carrier of a second RAT type, wherein the edge cell is adjacent to a coverage area covered by the second carrier, and wherein the idle hand-off indication signal represents an instruction allowing an idle hand-off to the second carrier;
- triggering the idle hand-off to the second carrier;
- and
- after triggering the idle hand-off to the second carrier and upon the access terminal camping on the second carrier, receiving an Inter-RAT Mobility Indication (IRMI) message from the access terminal at an access node of the second carrier.
A wireless cellular system comprising:
- a plurality of cells;
- a first portion of the plurality cells in a first coverage area and covered by a first carrier, wherein the first carrier has a first Radio Access Technology (RAT) type;
- a second portion of the plurality of cells in a second coverage area and covered by a second carrier, wherein the second carrier has a second RAT type;
- a third portion of the plurality of cells in a third coverage area covered by both the first carrier and the second carrier;
- at least one edge cell among the third portion of the plurality of cells that is located adjacent to the second coverage area;
- and
- an access node for the second carrier,
- wherein the system is configured to send an idle hand-off indication signal from the at least one edge cell to an access terminal that is attached to the first carrier and has entered into the edge cell,
- wherein the idle hand-off indication signal represents an instruction allowing an idle hand-off to the second carrier,
- wherein the system is configured to trigger the idle hand-off to the second carrier, and
- wherein the access node is configured to receive an Inter-RAT Mobility Indication (IRMI) message from the access terminal after the system triggers the idle hand-off to the second carrier and upon the access terminal camping on the second carrier.
Dependencies are inferred from the claim text.