A novel channel estimator for a superposition-based cooperative system

This paper investigates channel estimation and equalization for the relay node of a cooperative diversity system based on superposition modulation. Exploring the superposition structure of the transmission data, we propose a novel channel estimator for the relay node. Without any pilot sequence, the proposed estimator can converge to the ideal case as if the transmission data is known to the receiver. We also re-derive the soft-input-soft-output MMSE equalizer to match the superimposed data structure of the cooperative scheme. Finally computer simulation results are given to verify the proposed algorithm.