A Semi-Blind Multiuser Detection Based on Chebyshev Approximation and Subspace Tracking for MC-CDMA Uplink

In this paper, a new semi-blind multiuser detection based on a hybrid of Chebyshev approximation (CA) and subspace estimation is proposed for multicarrier code division multiple access (MC-CDMA) uplink. It is shown that the detector can be expressed as an anchored signal in the signal subspace and the coefficients can be estimated by CA algorithm. The spreading sequences of all known users are used to impose the linear vector constraints on the multiuser detector such that the interferers within the cell are suppressed effectively. To reduce the computational complexity, an improved projecting approximation subspace tracking with deflation (PASTd) algorithm is presented for adaptive subspace estimation. Simulation results demonstrate that the proposed semi-blind multiuser detection offers substantial performance gains over the blind multiuser detection in the MC-CDMA uplink environment