On Viterbi’s formula for the mean delay in a queue of data packets

An explicit formula for the mean waiting time in a discrete-time queue whose input is generated by N heterogeneous two-state Markovian sources was obtained by A.M. Viterbi. The paper shows that the same formula holds under more general conditions, provided that the terms involved are appropriately redefined. The method of proof exploits the structural features of the model, which may be described by a Markov chain of M/G/1 type.