Patent ID: 6026301
Filing Date: 2000-02-15
Classification: H04W

Abstract:
In a CDMA cellular network overlaid on an AMPS cellular network, a method for performing a handoff of a call from a mobile unit in a CDMA cell site of the CDMA cellular network wherein the CDMA cell site is co-located with an AMPS cell site of the AMPS cellular network, the method comprising the steps of:measuring a round trip delay (""RLTD"") value representing a distance from the mobile unit to the CDMA cell site;comparing the RTD value with a first predetermined value;if the RTD value exceeds the first predetermined value, determining whether any other CDMA cell site is available for handoff;comparing the RTD value with a second predetermined value;if the RTD value exceeds the second predetermined value, handing off the call to a second CDMA cell site if one is available; andif no other CDMA cell site is available for handoff, handing off the call to the AMPS cell site.