Design of an ATM switch for handoff support

In a wireless ATM system, a network must provide seamless services to mobil e users. To support this, mobility function should be added to existing ATM networks. Through a handoff operation, a mobile user can receive a service from the network without disconnecting the communication. A handoff result s in connection path rerouting during an active connection. To avoid cell l oss during a handoff, cell buffering and rerouting are required in the netw ork. A handoff switch is a connection breakdown point on an original connec tion path in the network from which a new connection sub-path is establishe d. It performs cell buffering and rerouting during a handoff. Cell bufferin g and rerouting can introduce a cell out-of-sequence problem. In this paper we propose a handoff switch architecture with a shared memory. The archite cture performs cell buffering and rerouting efficiently by managing logical queues of virtual connections in the shared memory and sorting head-of-lin e cells for transmission, thus achieving in-sequence cell delivery during a handoff. We also present simulation results to understand the impacts of h andoffs on switch performance.