Spread spectrum multiple access performance of orthogonal codes in fading multipath channels

Abstract

Indoor wireless communications (IWC) is an attractive alternative to wire-based local area networks. However, the indoor environment is characterized by fading multipath channels. Direct-sequence spread-spectrum techniques, with their inherent resistance to multipaths, are promising for IWC. To allow multiple users within a limited bandwidth, code division multiple access (CDMA) is needed. The authors analyze one relevant CDMA technique. A set of M-orthogonal sequences of length N is assigned to each of K users. The sequences consist of phase-modulated signals on the same carrier frequency. The bandwidth efficiency achieved over fading multipath channels is the presence of additive white Gaussian noise and multiple-access interference is determined.<>