A queueing model of an adaptive type-I hybrid-ARQ with a generalized Markovian source and channel

In this paper, the queueing performance of an adaptive type-I hybrid automatic repeat request (ARQ) with a generalized Markovian source is studied for a TDMA/TDD system over a Markovian channel. In the adaptive type-I hybrid ARQ of our interest, the pay load size for information in a packet (or ARQ block) and the coding rate of ARQ block vary, according to the channel state, e.g., high coding rate and small payload size for information in a bad state of channel. We assume that an arriving message over a medium access control (MAC) layer consists of a number of information units of fixed size. We analyze the delay of a message, which is composed of its queueing delay and its transmission time, and the message dropping probability. In the numerical examples, we have shown that the correlation of either traffic source or radio channel affects the queueing performance in a similar way, due to its Markovian structure. The analytical work presented here can be used to control physical parameters, such as coding rate, in order to meet QoS requirements in a higher layer which is over the MAC layer.