Recursive Compressed Sensing of Doubly-selective Sky-Wave Channel in Shortwave OFDM Systems

For shortwave OFDM systems under sky-wave doubly-selective channel conditions, the multi-path delay can be almost constant in several continuous OFDM symbols, while the path gain can be changed significantly along with the change of OFDM symbols. Based on the temporal-correlation properties of such a channel, we propose a recursive compressed sensing (CS) method of sky-wave channels with double selectivity in delayed Doppler domain. The recursive ideas is introduced into CS based double-selective channel estimation and the performance of channel estimation in the current OFDM symbol is improved by using the estimation results from the previous OFDM symbol as prior information. Simulation results show that the proposed recursive CS algorithm can take full advantage of the temporal correlation structure of channel sparsity, which result in the significantly reducing the pilot overhead.