Performance comparison of type I, II and III hybrid ARQ schemes over AWGN channels

Basically, there are two techniques to control errors in data communications, ARQ and FEC. The combination of these two techniques yields type I, II and III hybrid ARQ (HARQ) schemes. In this paper, we compare the performance of ARQ and different HARQ schemes based on theoretical results on the average number of transmissions and throughput on an AWGN channel. In type II HARQ, only a code combining strategy is considered which consists in alternatingly sending one of the outputs of a convolutional encoder.