On the Capacity of the Two-User Erasure Broadcast Channel with Mixed CSIT

This paper investigates the two-user Erasure Broadcast Channel (EBC), where the Channel State Information (CSI) is fully known at the destination, while the transmitter is only aware of the strictly causal CSI by state feedback and an estimate of the instantaneous CSI. We propose a novel transmission scheme that exploits both the delayed and the instantaneous CSI. Our scheme includes both the case with full CSI and the case with delayed CSI as special cases. We also derive a new outer bound region for this channel. For the symmetric EBC, we show that our scheme is capacity achieving in some nontrivial cases. Since both the inner and outer bound regions are characterized with linear constraints, numerical evaluation can be done easily.