Patent ID: 8086241
Filing Date: 2011-12-27
Classification: H04W

Abstract:
1. A handoff method for use in a mobile station, comprising: recording, by the mobile station, a first strength of a pilot signal from a serving cell of a 3G (third generation) CDMA (Code Division Multiple Access) system as a reference strength when a handoff occurs in the 3G CDMA system; triggering, by the mobile station, a handoff from the 3G CDMA system to a 2G (second generation) CDMA system when the mobile station is at a border cell of the 3G CDMA system and a second strength of a pilot signal from the serving cell of the 3G CDMA system reaches the reference strength; and adjusting the reference strength by a correction factor as follows: wherein Δ is the correction factor, E wherein X=(μPb/Rchip)×(Gb×Gm)/(Lb×Lm) and Y=(Pm,max×Gb×Gm)/(M×Lb×Lm), wherein Gb is a base station gain, Gm is a mobile station gain, M is an additional link margin to account for fading under soft handoffs, Pmax is a mobile transmission power, Pb is a power per carrier at the base station transmit filter input, μ is a fraction of base station power for the pilot, Rchip is a chip rate of the pilot, Lb is a base station loss, and Lm is a mobile station loss.