Hybrid Compression and Message-Sharing Strategy for the Downlink Cloud Radio-Access Network

Abstract—Cloud radio-access network (CRAN) is a wireless cellular network architecture in which the base-stations are connected to a cloud-computing based central processor with digital backhaul links. In this setting, the base-stations can be thought of as relays between the central processor and the user terminals. This paper considers the downlink of a cloud radio-access network with finite-capacity backhaul links. We model the overall network as a broadcast-relay channel, and propose a hybrid compression and message-sharing strategy for the downlink transmission. This paper further proposes numerical techniques for optimizing the quantization noise level in the compression part of the hybrid precoding scheme. We compare the system-level performance of the proposed scheme with the pure compression and the pure message sharing schemes to show the benefit of the hybrid strategy for the downlink CRAN. I