N-in-1 Retransmission with Network Coding

Retransmission (ReTX) mechanisms, i.e. Automatic Retransmission reQuest (ARQ) protocols are widely used for error control in mobile communications. Using ARQ, corrupted data frames are retransmitted in several attempts for eventual error recovery at the receiver. Error correction coding and soft combining have also been used in Hybrid ARQ (HARQ) protocols to increase efficiency. However, the evolution of ARQ protocols to date has been limited to the paradigm of ONE ReTX attempt for (the recovery of) ONE data frame, which often leads to excessive redundancies. In this paper we propose a new N-in-1 ReTX scheme. Using Random Network Coding, the scheme further improves the efficiency of ReTX by transforming a data frame into a series of equally-useful blocks for error recovery and sharing every ReTX attempt among multiple frames. Results from extensive simulations show that the proposed scheme achieves a significant throughput gain of up to 106% against the conventional HARQ-CC protocol.