Entities in communication systems behave under sets of communication rules (protocols) and their behaviours are related to each other. Using this relationship, we present a synthesis algorithm to derive a structured protocol model by generating a peer entity from a given entity automatically. The given entity is in the form of a communicating process, which is natural in the context of communication protocols. We prove that the synthesized protocol model consisting of the generated entity and the peer entity is safe: i.e. logical errors free, collectively represented as deadlock free and is bisimulated by both entities. Unlike many previous works, where FSMs (Finite State Machines) are used to synthesize protocol model we present our synthesis algorithm for the process-algebraic language LOTOS, which is one of the FDTs developed by ISO