Broadcasting Over Uncertain Channels with Decoding Delay Constraints

We examine communication over slowly-varying flat-fading additive white Gaussian noise channels with delayed channel state information feedback to the transmitter and finite decoding delay constraints. Under a block-fading channel model, it is shown that a broadcast strategy [8] maximizes the expected reliably received rate when the decoding delay constraint is one block and in certain cases when the delay constraint is two blocks. The latter requires a new analysis of underling parallel Gaussian broadcast channels which are not degraded in the same direction.