Opportunistic Hybrid ARQ—Enabler of Centralized-RAN Over Nonideal Backhaul

Centralized radio access networks rely on transport networks with very high throughput and very low latency. In the case of nonideal backhaul, it may be necessary to only centralize parts of the radio access network. This implies several timing and protocol constraints, e.g., predefined timing of retransmissions due to hybrid ARQ. In this paper, an opportunistic hybrid-ARQ approach is introduced, which estimates the decoding error probability at the radio access points and directly provides feedback to mobile terminals, while actual decoding is performed at the central processor. Furthermore, an effective signal-to-noise ratio (SNR) is derived, which allows for the use of a single mapping curve.