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To: S100 who wrote (100385)	6/14/2001 12:40:47 AM
From: S100	Read Replies (2) \| Respond to of 152472

Method and system for handoff between an asynchronous CDMA base station and a synchronous CDMA base station Abstract A method and system that enables faster acquisition of the forward link signal of a target base station in a mixed network of synchronous and asynchronous base stations is disclosed. The serving base station transmits in a neighbor list an estimated timing error 417 between the serving base station and a target base station. By utilizing the timing information, a mobile station estimates the relative time offset 408 between forward link signals received from the serving base station and signals received from the target base station. Timing information acquired during handoff enables accurate updating of the estimated timing error 417 subsequently transmitted in the neighbor lists by the base stations snip snip Base station time-synchronization as provided in the cdma2000 and IS-95 systems has many advantages with respect to system acquisition and handoff completion time. Synchronized base stations and time-shifted common pilot signals as discussed above permit a fast one-step correlation for system acquisition and detection of neighboring base stations. Once the mobile station has acquired one base station, it can determine system time that is the same for all neighboring synchronous base stations. In this case, there is no need to adjust the timing of each individual mobile station during a handoff between synchronous base stations. Additionally, the mobile station does not need to decode any signal from the new base station in order to obtain rough timing information prior to handing off. Another recently-proposed 3G communication system is referred to as W-CDMA. One example of a W-CDMA system is described in the ETSI Terrestrial Radio Access (UTRA) International Telecommunications Union (ITU) Radio Transmission Technology (RTT) Candidate Submission forwarded by ETSI to the ITU for consideration for the IMT-2000 CDMA standard. The base stations in a W-CDMA system operate asynchronously. That is, the W-CDMA base stations do not all share a common universal time reference. Different base stations are not time-aligned. Consequently, a W-CDMA base station may not be identified by its pilot signal offset alone. Also, once the system time of one base station is determined, this cannot be used to estimate the system time of a neighboring base station. For this reason, mobiles in a W-CDMA system use a three-step PERCH acquisition procedure to synchronize with each base station in the system. Each step in the acquisition procedure identifies a different code within a frame structure called a PERCH channel. snip Patent issued 12 June 2001 to 164.195.100.11