Specification and Description Language (SDL) is a high abstraction level system design language with a clear graphical notation. Because of formal presentation, an SDL model can be automatically converted into source C code for implementation. However, the high abstraction level creates a conceptual gap between a general SDL model and its implementation in a final operational platform. This paper studies the SDL development of an embedded Medium Access Control (MAC) protocol for a Wireless Local Area Network (WLAN) demonstrator. The SDL design flow for the protocol is first started by architectural design without target platform dependencies. Functionality is added to the model using the top-down design approach. Functional simulations are used for verifying the operation of the protocol. Next, the performance is estimated using performance simulations in a workstation environment. Performance improvements can be achieved by optimizing the SDL model.