On Broadcast Approach to MIMO Fading Channels

We consider a general point-to-point fading multiple-input multiple-output (MIMO) Gaussian channel. The channel suffers block fading and with finite channel states, among which there is no degraded order on state information due to multi-antenna deployment. To guarantee reliable transmissions under arbitrary unpredictable fading states, we generalize the layered broadcast approach in the channel by inducing a rate splitting scheme. It assigns a specific sub-message layer for every possible state set and splits the transmission rate by allocating power to each layer. Under this scheme, a generalized broadcast approach is designed to be suitable for multi-antenna transmission. The maximum average rate under total power constraint can be characterized by an optimization problem. Numerical examples are provided to show the optimality of our transmission scheme within degradedness among different channel state information. Meanwhile, such generalization can also provide a decent performance under the general non-degraded case.