Optimal interference pre-cancellation order in DPC-based broadcast and unicast hybrid network

It is well known that the Dirty Paper Coding (DPC) achieves the channel capacity for multiuser degraded channels. However, the optimality of DPC remains unknown for nondegraded channel. In this paper, we derive the optimal interference pre-cancellation order for a DPC based broadcast and unicast hybrid network. Specifically, we study different DPC cancellation schemes to maximize the hybrid capacity region. The conditions for each scheme being optimal are analytically derived. Our results show that the optimal interference precancellation order varies with SNR and broadcast and unicast channel conditions.