Signature Code Design for Fast Fading Channels

We address the problem of codebook design for sparse user detection in fast fading channels, where the fading realization changes from channel use to next. In this scenario, codebook design criteria based on quasi-static fading, and/or channel state information at the receiver, become ineffective. In this paper we suggest new code design principles for signature coding in fast fading channels and provide examples of codes that are built using these methods.