System and method for GSM hard handoff
First Claim
Patent Images
1. A method of handoff from a CDMA network to a GSM network, comprising:
- determining a mobile is served by a CDMA border cell, the mobile including a GSM1×
protocol stack for performing handoff procedures to a CDMA network, and a GSM protocol stack for performing handoff procedures to a GSM network;
sending the mobile a list of candidate GSM cells after determining the mobile is served by a CDMA border cell;
sending a Mobile Switching Node (MSN) a candidate frequency search response message after receiving the list of candidate GSM cells;
sending the mobile a candidate frequency search control message indicating that the mobile measure a surrounding GSM network;
measuring the surrounding GSM network;
sending a report of the measurements to the MSN; and
selecting a GSM cell for handoff based on the report.
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Abstract
A GSM1×-to-GSM handoff feature allows a GSM1× subscriber with a dual-mode (GSM1× and GSM modes) handset to seamlessly roam from GSM1× coverage areas to GSM coverage areas. This functionality is facilitated by the GSM1× system design which integrates a CDMA RAN with a standard GSM core network. The GSM1× system is built using standard CDMA as its air interface and an unmodified CDMA RAN with a standard IOS interface to the MSN. The only modifications are done at the MSN and the MS.
53 Citations
6 Claims
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1. A method of handoff from a CDMA network to a GSM network, comprising:
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determining a mobile is served by a CDMA border cell, the mobile including a GSM1×
protocol stack for performing handoff procedures to a CDMA network, and a GSM protocol stack for performing handoff procedures to a GSM network;sending the mobile a list of candidate GSM cells after determining the mobile is served by a CDMA border cell; sending a Mobile Switching Node (MSN) a candidate frequency search response message after receiving the list of candidate GSM cells; sending the mobile a candidate frequency search control message indicating that the mobile measure a surrounding GSM network; measuring the surrounding GSM network; sending a report of the measurements to the MSN; and selecting a GSM cell for handoff based on the report. - View Dependent Claims (2, 3)
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4. A Mobile Switching Node (MSN), comprising:
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means for determining a mobile is served by a CDMA border cell, the mobile including a GSM1×
protocol stack for performing handoff procedures to a CDMA network, and a GSM protocol stack for performing handoff procedures to a GSM network;means for sending the mobile a list of candidate GSM cells after determining the mobile is served by a CDMA border cell; means for sending the mobile a candidate frequency search control message indicating that the mobile measure a surrounding GSM network; and means for selecting a GSM cell for handoff based on a report from a mobile of measurements of a mobile'"'"'s surrounding GSM network.
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5. A dual-mode mobile station, comprising:
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an antenna for receiving and transmitting signals; a duplexer coupled to a transmitter and a receiver for switching between a transmitter and receiver; a receiver coupled to the duplexer for receiving signals; a transmitter coupled to the duplexer for transmitting signals; a GSM1×
protocol stack used for performing handoff procedures to a CDMA network;a GSM protocol stack used for performing handoff procedures to a GSM network; and a processor coupled to the GSM1×
protocol stack and the GSM protocol stack for performing handoff between CDMA and GSM networks, the processor also coupled to the receiver and transmitter for receiving and transmitting signals, respectively.
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6. Computer readable media embodying a program of instructions executable by a computer program to perform a method of handoff from a CDMA network to a GSM network, the method comprising:
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determining a mobile is served by a CDMA border cell, the mobile including a GSM1×
protocol stack for performing handoff procedures to a CDMA network, and a GSM protocol stack for performing handoff procedures to a GSM network;sending the mobile a list of candidate GSM cells after determining the mobile is served by a CDMA border cell; sending a Mobile Switching Node (MSN) a candidate frequency search response message after receiving the list of candidate GSM cells; sending the mobile a candidate frequency search control message indicating that the mobile measure a surrounding GSM network; measuring the surrounding GSM network; sending a report of the measurements to the MSN; and selecting a GSM cell for handoff based on the report.
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Specification