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Giving users simple access to QoS selection capability of ATM networks is important for the future of integrated services networks. We describe the rst instance of an application in which users had the capacity t o t u n e A TM tra c parameters with a button, at run time. To a c hieve t h i s w e implemented the necessary signaling extension on ATM switches as well as on end-systems. Furthermore, we extended Arequipa (Application REQested IP over ATM a mechanism that enables applications to request direct ATM connections for their exclusive use, and to directly control their trafc parameters) to support modi cation, and modi ed the popular Mbone tool Vic (VIdeo Conferencing) to use Arequipa to request and modify ATM bandwidth at will. We describe how Vic accomplished this over the ATM WAN of SWISSCOM, transferring live video from Lausanne to Basel over switched, renegotiable ATM connections.

We have created a large-scale information delivery platform optimized for mobile phones and used it for many months now to run a content delivery service through SMS. We share the key findings from our experience of serving many millions of short messages each month to over 1 million subscribers.

Abstract-We describe enhancements to the IEEE 802.11 DCF MAC Protocol which enable nodes to identify themselves as exposed nodes and to opportunistically schedule concurrent transmissions whenever possible, thereby improving utilization and mitigating the exposed node problem. The algorithm makes minimal changes to the IEEE 802.11 MAC protocol. It does not require making changes to frame formats or the introduction of new frame types. We show, using simulations in GloMoSim, that it provides significant improvement in throughput.