Queueing performance of an adaptive type-I hybrid-ARQ scheme over a markovian channel

In this paper, we investigate a queueing perfor- mance of an adaptive Type-I hybrid-Automatic Repeat re- Quest(ARQ) scheme in a TDMA System over a Markovian channel. In the system, we assume that an arriving message of variable size over a medium access control(MAC) layer consists of a number of information units of fixed size. It is fragmented in a MAC/LLC layer according to the payload size of ARQ block of fixed size and transmitted. The payload size of ARQ block varies in accordance with each channel state in order to increase the packet transmission success probability. The system of interest is modelled as bulk arrival and modulated bulk service in an infinite buffer and solved by a generating function approach. From the queueing analysis, we obtain the message delay, which is its queueing delay plus the time to transmit the entire message, by inverting the generating function. In the numerical examples, the queueing performance of a non-adaptive hybrid type-I and adaptive one is compared. The adaptive one maintains its queueing performance over a wide range of bit error rate(BER) while that of non-adaptive one is highly sensitive to BER. In addition, a slowly-varying channel shows worse queueing performance, because the channel whose bad state shows low BER and long period causes higher queueing delay than the channel with counterpart parameters. I. INTRODUCTION