Pilot symbol assisted schemes: a better alternative to systematic unitary constellations for the non-coherent fast fading channel

This work deals with the design of coding/modulation and demodulation/decoding schemes for multiple-antenna systems. We focus on fast fading channels where channel state information is not available at the transmitter and receiver. It is shown that when turbo-like outer codes are considered, the optimized unitary constellations previously investigated are inferior to constellations that utilize simple inner space-time block codes. More importantly, the latter schemes have a rich structure that can be exploited at the receiver to design very low complexity iterative decoding algorithms. We provide examples for which the proposed scheme results in a performance improvement simultaneously with a complexity reduction.