Performance evaluations of hybrid automatic repeat request schemes for a data communication system

Abstract It is generally impossible to avoid occurrences of errors of the data transmission because of the disturbing factors such as disconnections, noises or distortions in a communication line. Therefore, the error‐control procedure is indispensable to trnnsmit high‐quality data and its various techinques have been considered from the viewpoints of high reliability data transmission. the main techniques in the error‐correcting strategies are classified into the following three categories: (i) forward‐error‐correction (FEC) scheme; (ii) automatic‐repeat‐request (ARQ) scheme; and (iii) hybrid ARQ scheme. the hybrid ARQ scheme is the system combined FEC scheme with ARQ scheme. This aims to reduce the frequency of retransmissions as much as possible and to gain a constant data throughput, even in a worse communication environment, by coding error patterns that would be expected to occur frequently. However, when the first data of transmission has failed, the hybrid ARQ is removed to the ARQ policy with the same FEC, i.e., its data throughput decreases because of bit increments, such as codes to correct errors in the data transmission. This is called type‐I hybrid ARQ and its modified systems, which are called type‐II hybrid ARQ, have been studied and proposed by many authors. This paper suggests a new type‐II hybrid ARQ system from the viewpoint of improving the data throughput and derives the mean time to success of the data transmission. Then, the mean times of the system are compared analytically with those of the usual ARQ and the type‐I hybrid ARQ, and an evaluation is done.