In this paper, we consider parameter estimation for a FIFO queue with
deterministic service times and two independent arrival streams of ''o
bserved'' and ''unobserved'' packets. The arrivals of unobserved packe
ts are Poisson with an unknown rate lambda while the arrivals of obser
ved packets are arbitrary. Maximum likelihood estimation of lambda is
formulated based on the arrival times and waiting times of k observed
packets. The likelihood function is derived in terms of the transition
probabilities of the unfinished work process which are calculated rec
ursively. Sufficient conditions for consistency, asymptotic normality,
and asymptotic efficiency are given. The mean and variance of the MLE
are measured in simulation experiments. Numerical results indicate th
at the MLE is consistent and asymptotically normal.