On the performance of antenna arrays in spatial reuse TDMA ad hoc networks

Abstract

We have investigated how, the capacity and average delay can be improved by using antenna arrays in an ad hoc network with Spatial Time Division Multiple Access (STDMA). The study is based on different antenna combinations consisting of a single isotropic antenna element, beam steering and adaptive beamforming. We have also studied how the number of antenna elements and the terrain affects the performance. The study shows that the maximum capacity is improved dramatically for the examined networks, with up to 980%. In addition, the average delays are decreased substantially when using antenna arrays. Depending on the beamforming combination used, the capacity gain and the average delay reduction will differ. The highest capacity gain is achieved when combining beam steering (transmitting node) and adaptive beamforming (receiving node). For broadcast traffic omni-directional transmission is most feasible (no transmit beamforming); however,,ever, beamforming is still possible in the receiving nodes. For this beamforming combination the capacity gain is significant, about 560%. The study also indicates that the benefit from antenna arrays is higher in aflat terrain than in a rough terrain.