Integrating the Physical and Link Layers in Modeling the Wireless Ad Hoc Networking MAC Protocol, Synchronous Collision Resolution

Providing a set of protocols that will support the demands of mobile wireless ad hoc networking is fraught with many challenges. Despite over 30 years of research and effort, ad hoc networking still remains a field of research rather than a field of practice. Many of these challenges, however, are created by the use of an inappropriate paradigm to define the network's behavior.

To date, the bulk of the research in this area has used a wired paradigm. We propose a new wireless paradigm that we believe is more suitable. The significance of the paradigm is that the wired paradigm tends to promote research in routing and higher layer protocols as a result of over simplifying the behavior of the link and physical layers. The wireless paradigm reveals that most of the networking functionality needs to be implemented at the link and physical layers.

In this paper, we contrast the different paradigms and explain how the protocol, Synchronous Collision Resolution (SCR), provides a framework for implementing algorithms that will solve the challenges of ad hoc networking according to the wireless paradigm. To conduct research in this area, and to ultimately answer critics' concerns about the impact of the unreliable physical layer on the performance of SCR, have required us to make a sophisticated model of the physical layer. We describe how we implemented such a model using OPNET's Modeler environment.