Absolute Amplitude Differential Phase Spatial Modulation and Its Non-Coherent Detection Under Fast Fading Channels

Amplitude phase shift keying (APSK) aided differential spatial modulation (APSK-DSM) is a multiple-input-multiple-output wireless transmission technique which not only has the desirable features of differential spatial modulation (DSM) but also has a higher spectrum efficiency than DSM. However, the error propagation problem and the violation of the quasi-static channel assumption in conventional APSK-DSM design will cause significant performance loss, especially in undesirable channel conditions. Besides, the maximum-likelihood detection based on the traditional block-by-block search has a complexity that grows exponentially with the block size, which becomes intractable in systems with large transmit antenna numbers. To overcome those drawbacks, we propose a novel transmission scheme named the absolute amplitude differential phase spatial modulation (AADP-SM) in this paper. AADP-SM is able to alleviate the error propagation problem and achieve a near-coherent performance by invoking multiple previous blocks in the current detection. By taking into account the channel fading rate, AADP-SM is also more robust in fast-fading channels than APSK-DSM. A novel non-coherent detection algorithm is proposed for AADP-SM to reduce the exponential detection complexity to a polynomial order. Finally, we show through simulation that AADP-SM is tolerable to imperfect information about the channel statistics.