A generalized framework - periodically scrambled CDMA

In this paper, a generalized framework - periodically scrambled CDMA is proposed. The basic idea is to use periodic scrambling instead of the conventional pseudo-random scrambling. The period of the scrambling code can either be the same or different from that of the channelization code. Each user can be assigned a specific pair of channelization code and scrambling sequence to modulate its message signal. The overall system is therefore a "structured long code system", existing short code, long code and semilong code systems are all special cases of the proposed scheme. In this paper, following the system modeling, channel estimation and signal separation are presented for both uplink and downlink periodically scrambled CDMA. The proposed framework potentially can provide more flexibility in mobile management and cross-layer optimization for broadband access multimedia systems.