Asynchronous Multihop Wireless Networks for Real-time Support

Abstract

Personal communications and mobile computing will require a wireless network infrastructure which is fast deployable, possible multihop, and capable of multimedia service support. The first infrastructure of this type was the Packet Radio Network (PRNET), developed in the 70’s to address the battlefield and disaster recovery communication requirements. PRNET was totally asynchronous and was based on a completely distributed architecture. It handled datagram traffic reasonably well, but did not offer efficient multimedia support. Recently, under the WAMIS and Glomo ARPA programs several mobile, multimedia, multihop (M3) wireless network architectures have been developed, which assume some form of synchronous, time division infrastructure. The synchronous time frame leads to efficient multimedia support implementations. However, it introduces more complexity and is less robust in the face of mobility and channel fading. In this paper, we examine the impact of synchronization on wireless M3 network performance. First, we introduce MACA/PR, an asynchronous network based on the collision avoidance MAC scheme employed in the IEEE 802.11 standard. Then, we evaluate and compare several wireless packet networks ranging from the total asynchronous PRNET to the synchronized cluster TDMA network. We examine the tradeoffs between time synchronization and performance in various traffic and mobility environments.