CELLULAR RADIOTELEPHONE COMMUNICATION SYSTEMS AND METHODS OF UPLINKING DOWNSAMPLED SIGNALS FROM CELLULAR RADIOTELEPHONE BASE STATIONS TO A CELLULAR RADIO EXCHANGE

摘要

Cellular radiotelephone communication systems and methods downlink digital coded speech from a cellular radio exchange to a cellular radiotelephone base station and uplink downsampled (i.e. undersampled relative to the Nyquist rate of two samples per symbol) radiotelephone signals from the cellular radiotelephone base station to the cellular radio exchange. The downsampled radiotelephone signals are demodulated at the cellular radio exchange and the digital coded speech is modulated at the cellular radiotelephone base station. Diversity demodulation may be used at the cellular radio exchange, to diversity demodulate the downsampled radiotelephone signals at the cellular radio exchange. By downlinking digital coded speech from the cellular radio exchange to the cellular radiotelephone base station, and uplinking downsampled radiotelephone signals from the cellular radiotelephone base station to the cellular radio exchange, narrowband uplinks and downlinks may be provided between the base stations and the cellular radio exchange, to thereby reduce cost. Moreover, since demodulation takes place at the cellular radio exchange rather than at the base stations, low cost base stations may be provided. However, since downsampled radiotelephone signals are transmitted from the base stations to the cellular radio exchange, diversity demodulation may be performed at the cellular radio exchange, to thereby improve the voice quality of the cellular radiotelephone communications.