The impact of error control on energy-efficient reliable data transfers over optical networks

In this paper, we study the efficacy of error control schemes for energy-efficient reliable delivery of large files (hundreds of GBs) over core optical networks. Specifically, we examine two schemes: automatic repeat request (ARQ), and hybrid ARQ (i.e. ARQ combined with forward error correction (FEC) capability). We focus on Reed-Solomon (RS) FEC codes (in hybrid ARQ) and propose a new model, incorporating different block sizes as well as code error-correction capability, to estimate the energy consumption for performing encoding and decoding operations in optical networks. The model considers the impact of varying pre-FEC bit-error rates (BER) of the optical channel, and the signal processing blocks used to implement RS codes. Our results show that when the pre-FEC channel BER is in excess of 10^-5, hybrid ARQ offers better performance than ARQ in terms of energy efficiency. However, both hybrid ARQ and ARQ have similar performance under lower BER.