Terrestrial communication between wireless sensor networks using beam-forming and space division multiple access

Abstract

In this thesis, methods for forming a communications link of Wireless Sensor Networks (WSN) by enabling each WSN to act as a smart antenna are presented. Each WSN is simulated as a set of randomly placed sensor nodes within a planar area. The proposed method involves a searching WSN, a receiving WSN and a link budget for establishing the link. The searching WSN has the task of transmitting a search beam in order to find adjacent WSNs. Like a lighthouse this is done in a rotating beam style search using the sensor nodes as an aperiodic array. Results show that for a random array, we can achieve a specific beamwidth and gain as a function of the number of elements and area. We also demonstrate that for a given required gain level we can spatially thin the array without significant loss of gain or the effects of grating lobes. The receiving WSN uses a spread spectrum based space division multiple access (SDMA) receiver. This receiver is simulated to determine the direction of arrival from the searching WSN and to extract the location information from the searching WSN's signal with additive white Gaussian noise. From the DOA and the location information within the arriving signal, the WSN has sufficient knowledge to respond to the query of the searching WSN and form the communications link.