Single code cyclic shift detection - A pilot aided CDMA multiuser detector without using explicit knowledge of signature codes

A new pilot-aided multiuser detection scheme, single code cyclic shift (SCCS) detector, is proposed in this paper for synchronous CDMA multiuser signal reception. The unique feature of the proposed detector is that a receiver can decode multiuser signals even without explicit knowledge of all signature codes active in the system. The transmitting signal from a base station to a mobile contains two separated channels: the pilot and data channels; the former consists of periodically repeated pilot symbols encoded by the same signature codes as the one spreading the latter. Both pilot and data signals for a specific mobile are sent by a base-station using quadrature and in-phase carriers at the same frequency with QPSK modulation. A matched filter bank, consisting of M correlators that match to distinct cyclic-shifted versions of a "single" signature code, is employed for "channel cyclic shift correlation function" estimation, followed by the multiuser detection algorithm based on the channel information obtained earlier. The performance of the proposed SCCS detector is evaluated and compared to decorrelating detector by computer simulations considering various multipath channels with different profiles. The results demonstrate that a synchronous CDMA joint detection can be implemented successfully without necessarily knowing all signature codes of the system.