Semi-blind pilot-layer aided channel estimation with emphasis on interleave-division multiple access systems

A channel estimation scheme for Interleave-Division Multiple Access (IDMA) systems is presented. Training and data are superimposed, i.e., no bandwidth expansion compared to a system without any training is necessary. A semi-blind linear Minimum Mean Squared Error (MMSE) channel estimator is derived. Monte Carlo simulation results are presented showing that the derived channel estimator in combination with the proposed training scheme is able to track fast-fading frequency-selective channels. As opposed to conventional channel estimation techniques, the BER performance even improves with increasing Doppler spread. An error performance close to the case of perfect channel knowledge can be achieved with high power efficiency.