DS/CDMA prototype system transmitting low bit-rate voice and high bit-rate ISDN signals

The DS/CDMA prototype system described can transmit low bit-rate voice and high bit-rate ISDN signals in the ISM band. The robust error correction scheme uses interleaving, convolutional coding, and Reed-Solomon coding; it ensures high quality voice and ISDN signals. The relationship between the SNR and and the number of quantizing bits output by the ADC of SS signals has been evaluated, and it has been shown that an ADC with few-bits has minimal SNR degradation in CDMA systems. The received and despread signals are quasi-coherently detected in the forward link by referring to the phase of the pilot signal, whereas in the reverse link, non-coherent or differential detection is used. The proposed DS/CDMA prototype system has shown to achieve good performance in various experiments using a wireless TV-phone, developed as a potential ISDN application