Adaptive arrays in packet radio

Abstract

The authors describe how a multiple beam adaptive antenna (MBAA) may be used to improve the performance of a random access packet radio communication network. In such networks, packets arriving at a terminal receiver compete for the use of the radio channel. Collisions between uncoordinated packets limit the average throughput and increase the network delay. A multibeam adaptive array used at a packet receiver can eliminate nearly all collisions between packets and hence is a very attractive technique for improving the performance of such networks. The authors describe the procedure used for rapid signal acquisition with the adaptive array and the effect of the array on network performance for a simple slotted ALOHA network. Each beam captures a different packet in a slot by automatically pointing its beam toward that packet and nulling other packets in the slot. Such a system permits average throughputs on 2-4 packets per slot with only modest MBAA capabilities.< >