Quality-of-service in ad hoc carrier sense multiple access wirelessnetworks

摘要

Carrier sense multiple access (CSMA) is one of the most pervasivenmedium access control (MAC) schemes in ad hoc, wireless networks.nHowever, CSMA and its current variants do not provide quality-of-servicen(QoS) guarantees for real-time traffic support. This paper presents andnstudies black-burst (BB) contention, which is a distributed MAC schementhat provides QoS real-time access to ad hoc CSMA wireless networks.nWith this scheme, real-time nodes contend for access to the channel withnpulses of energy-so called BBs-the durations of which are a function ofnthe delay incurred by the nodes until the channel became idle. It isnshown that real-time packets are not subject to collisions and that theynhave access priority over data packets. When operated in an ad hocnwireless LAN, BB contention further guarantees bounded and typicallynvery small real-time delays. The performance of the network can approachnthat attained under ideal time division multiplexing (TDM) via andistributed algorithm that groups real-time packet transmissions intonchains. A general analysis of BB contention is given, contemplatingnseveral modes of operation. The analysis provides conditions for thenscheme to be stable. Its results are complemented with simulations thatnevaluate the performance of an ad hoc wireless LAN with a mixednpopulation of data and real-time nodes