Importance

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Abstract

A method for handoff of an analog connection within a cellular communication system which relies upon mobile station synchronization to a system time is disclosed herein. In order to reduce the acquisition time for a mobile station commencing operation in a digital mode, an estimate of master system time is transferred to the mobile station in analog mode before entering digital mode. The alignment operates within the protocols of existing analog systems, and hence requires only minimal changes in the mobile station. Time alignment may be initiated upon the base station sending to the mobile station a command to continually transmit a periodic signaling tone. The base station compares the phase of the signaling tone from the mobile station to a master system clock and determines an error signal. The base station notifies the mobile station to delay or advance in time the transmitted signaling tones based on the error signal. This procedure may continue until the calculated error falls below a predetermined level. Having attained time alignment, the base station is able to transfer to the mobile station absolute time of day information with increased accuracy. The mobile station is then commanded into digital mode where transition time is reduced to a level tolerable by the end user due to the performed alignment.

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First Claim