1.6 Mbit/sec high capacity land mobile transmission characteristics of differential coding CDMA over multi-ray Rayleigh fading channel

Abstract

Differential coding CDMA (diffCDMA) is verified to conquer the fatal transmission error when communications are carried from high speed vehicles running through an urban environment with rapid multi-ray Rayleigh channels. With the introduction of differential coding into the primary modulation and employing analytic receiving for primary differential demodulation, the proposed diffCDMA system improves the transmission characteristics of similar CDMA systems such as IS-95 and WcdmaOne IMT2000 for mobile communications at vehicle speeds of more than 100 mile/h mobiles even if a multi-ray environment. Previously, differential coding primary modulation has not been considered for use with CDMA owing to the strict sense synchronization required in demodulation, which suffered from bit error under such rapid multi-ray Rayleigh fading. However, its use is now possible in high speed and high capacity transmission since analytic receiving is being adopted into CDMA systems. In the demodulation procedure of the diffCDMA, the received waves are first detected after multi-ray propagation with certain inevitable errors both in phase and frequency of the recovered carrier for the pseudo synchronization primary demodulation during analytic receiving.