Oversaturated Group Orthogonal CDMA in Multipath Channels using Chip Interleaving with Zero Padding

Oversaturated group orthogonal CDMA (GO-CDMA) offers an elegant way of increasing capacity of synchronous DS-CDMA, which allows existence of number of users exceeding signal space dimension. The system provides excellent results in synchronous single-path channels; however, in multipath channels complicated equalizers of big length are required to secure good performance due to significant MAI. In this paper implementation of chip interleaving with zero padding in GO-CDMA system is considered to alleviate the effect of MAI. It is shown that this approach results in bit-synchronous multipath signals at the receiving end. Computer simulations demonstrate that in such a system the usage of the simplest zero-forcing equalizer of moderate length provides performance very close to that of GO-CDMA in an AWGN channel.