In this paper, we propose a method to synthesize protocol specifications automatically from service specifications written in a time-extended LOTOS called LOTOS/T+. In LOTOS/T+, structured descriptions, such as parallelism and interruption are allowed to describe service specifications, and time-constraints among non-adjacent actions can be described using Presburger formulas. Here we assume that there is a reliable communication channel between any two nodes and the maximum communication delay for each channel is bounded by a constant. Moreover we assume service specifications have no deadlocks. Under our simulation policy, a specification S' is derived from a given service specification S and a given maximum communication delay of each channel. In S', time-constraints necessary for exchanging synchronization messages are added. If S and S' can carry out the same behaviour, i.e., if S and S' are bisimulation equivalent when time is ignored, then a correct protocol specification for simulating S is derived from S' automatically