Overview

SWAN represents a simple, stateless network model that uses distributed control algorithms to support "soft" real-time services and service differentiation in wireless ad hoc networks. SWAN uses rate control for UDP and TCP best-effort traffic and sender-based admission control for UDP real-time traffic. In addition, SWAN uses explicit congestion notification (ECN) to dynamically regulate admitted real-time traffic in the face of network dynamics brought on by mobility or traffic overload conditions. We use the term "soft" real-time services to indicate that real-time sessions could be regulated or dropped due to mobility or excessive traffic overloading at wireless routers. SWAN is designed to limit such conditions, however. A novel aspect of SWAN is that it does not require the support of a QOS-capable/real-time MAC. Rather, soft real-time services are built using existing best effort wireless MAC technology.