RVK 99: Adaptive Antennas in Spatial TDMA Multihop Packet Radio Networks

Multihop Packet Radio Networks (MHPRN) is an alternative for reliable rural data transmission where no telecommunication infrastructures exist. A key issue in designing such networks is the selection of Medium Access Control (MAC) strategy. Spatial TDMA is a MAC protocol proposed for MHPRN where links are pre-assigned time-slots according to a schedule in such way that interference is avoided allowing dense reuse of time slots within the network. Terrain obstacles act as shields to interference and may produce better performance. In this paper it is shown that use of simple adaptive directional antennas in rough terrain considerably improve the throughput and delay performance of MHPRN using STDMA. Using fourelement linear antenna arrays at both transmitter and receiver ends of a link controlled to maximize the received power, provide a significantly reduction in the average packet delay and up to 70% capacity improvement respect to a reference system using omnidirectional antennas.