VARIABLE RATE SIGNAL TRANSMISSION IN A SPREAD SPECTRUM COMMUNICATION SYSTEM USING COSET CODING

摘要

An improved system and method for communicating information at variable datarates over in-phase (I) and quadrature phase (Q) communication channels in aCDMA spread spectrum communication system is disclosed herein. In an exemplaryimplementation an input information signal is transmitted over either an I orQ communication channel using a direct sequence spread spectrum communicationsignal. The information signal is initially divided into first and secondsubsignals, which are respectively provided to first and second coset-encodingnetworks. The first coset-encoding combines the first subsignal with a firstcoset code, while the second coset-encoding network combines the secondsubsignal with a second cosed code orthogonal to the first cosed code. In thisway the first and second coset-encoding networks are operative to producefirst and second coset-encoding signals, respectively. A composite coset-encoded signal formed from the first and second coset-encoded signals is thenmodulated by an orthogonal function signal to provide a first modulatedsignal. In-phase pseudorandom noise (PNI) and quadrature phase pseudorandomnoise (PNQ) signals of predetermined PN codes are used for spreading the firstmodulated signal for transmission to a receiver over either the I or Qcommunication channel, respectively. The receiver is operative to produce anestimate of the input information signal on the basis of the modulated carriersignal received over either the I or Q communication channel.