A RAPID-ACQUISITION ACCESS CHANNEL SCHEME FOR CDMA SYSTEMS

摘要

A spread spectrum CDMA communication system in which a station transmits a short synchronization signal to allow a second station to (1) recognize that a signal is present, (2) resolve frequency uncertainty, (3) acquire the spreading code timing, (4) acquire frame and symbol synchronization, and (5) demodulate data which may contain user identification and other data. The rapid acquisition channel (RAC) includes a burst signal comprising of an Acquisition Field during which the carrier is biphase modulated with a pseudo-noise (PN) sequence, a Sync Field during which a synchronization sequence is mod-2 added to the PN sequence with one chip of the sync sequence equal to one or more periods of the PN sequence, and a data field with m-ary orthogonal code words mod-2 added to the PN sequence with one chip of the code word equal to one or more periods of the PN sequence.