On the separability of demodulation and decoding for communications over multiple-antenna block-fading channels

We study the separability of demodulation and decoding for communications over multiple-antenna block-fading channels when bit-linear linear dispersion (BL-LD) codes are used. We assume the channel is known to the receiver only, and find necessary and sufficient conditions on the dispersion matrices for the separation of demodulation and decoding at the receiver without loss of optimality.