Time-varying linear dispersion coding over frequency-selective fading channels

In this paper, we first introduce a (redundant) filterbank precoder framework for linear dispersion coding over frequency-selective fading channels, where the linear dispersion of information-bearing symbols over time has been shown by a synthesis filterbank structure whose filters are linear temporal dispersive encoders. Well-known zero-padding method would be applied to avoid IBI and changing the problem to LD coding over (virtual) flat-fading channels. Based on the proposed framework, coding in the transmitter and decoding in the receiver would be straightforward. Then, as the major novelty of the paper, we will propose time varying linear dispersion coding and it would be shown that choosing time varying filters as encoders would cause some modifications on the coding gain. Also it has been shown that the impairments caused due to 'zero-padding + frequency selectivity", could be compensated by time varying encoders. Simulation results would confirm our idea.