Method and apparatus for facilitating establishment of communications in a messaging system

摘要

A digital sync signal (502) is transmitted (702) from K transmitters (206) of a cluster (402), followed by K fine tuning signals (506) during K time slots (510), each time slot assigned to a transmitter. Each fine tuning signal comprises a pair of tones (512) separated in frequency by a predetermined amount. A portable subscriber unit (122) receives (706) the sync signal and the fine tuning signals, and makes (708) a rough estimate of the beginning of the fine tuning signals from the sync signal and from knowledge about the time slots. The portable subscriber unit computes (710) for each time slot a 2M-point Fourier transform (FT) on a received signal including M fine tuning signals received during the time slot from a transmitter of the cluster and from M-1 corresponding transmitters of adjacent clusters (404). The portable subscriber unit then fine tunes (722) the rough estimate through FT calculations.