Robust Layered Transmission and Compression for Distributed Uplink Reception in Cloud Radio Access Networks

In the uplink of cloud radio access networks, each base station (BS) compresses the received signal before transmission to the cloud decoder via capacity-limited backhaul links. A major issue in designing the transmission strategy at the mobile stations (MSs) and the compression strategies is the lack of channel state information (CSI) relative to the signal received by BSs in other cells. To tackle this problem, this paper proposes layered transmission and compression strategies that aim at opportunistically leveraging more advantageous channel conditions to neighboring BSs. A competitive robustness criterion is adopted, which enforces the constraint that a fraction of the rate that is achievable when the CSI is perfectly known to the MSs and the BS in the cell under study should be attained also in the absence of CSI. Under competitive robustness and backhaul capacity constraints, the problem is formulated as the minimization of the transmit power. Extensive numerical results confirm the effectiveness of the proposed approaches.