Synthesis Of Randomly Spaced Antenna Arrays For Wireless Sensor Networks

A Wireless Sensor Network (WSN) is a self-organized wireless network of sensors. The nodes collect and process the data, then transfer the data to the sink node. The sink node, which has the wireless transmitting function, keeps on sending the data to the control center. However, sometimes the control center is so faraway that the sink node can't provide enough power for distant communication. As for this problem, we provide a beamforming method by making the nodes elements of an antenna array to form a high gain beam and meet the required SNR.Since the WSN nodes are arbitrarily distributed, the WSN beamforming problem is actually a synthesis problem of randomly spaced antenna arrays with arbitrary distribution. Research of randomly spaced antenna arrays began in early 1960s; however, no succeeding research was done due to the complexity of engineering fulfillment. People put more attention to antenna arrays that can partially substitute for randomly spaced arrays but easier to implement, such as unequally spaced antenna arrays or tapered arrays. In order to build up WSN beamforming theory, we take up the research of randomly spaced antenna arrays again and make a synthesis theory of randomly spaced arrays for WSN.In this article, a 2-dimensional randomly spaced antenna array model with arbitrary distribution is built up, and in the meaning of forming the maximum gain, we simplify the 2-D synthesis problem into an equivalent 1-D one. By making the pattern of the randomly spaced array approach the pattern of an antenna with continuous aperture, we make the synthesis of the current amplitude distribution over the aperture equivalent to that over a continuous one, and the later is fully developed in antenna technology. We also propose a synthesis method immune to inaccurate positioning of WSN nodes. In order to mitigate the adverse effect of mutual coupling, a compensation method using parallel Gauss-Seidel iterative algorithm is addressed. The simulation result verified the effectiveness of this algorithm.In this article, we proved the possibility of WSN data transmission by beamforming. The main parameters of randomly spaced antenna arrays, like the amplitude distribution over aperture, the phase-shift, the pattern sidelobe level distribution, and the mutual coupling effect, are studied. And a whole set of theory for WSN randomly spaced array synthesis is provided. Further study could be the combining of this theory with the physical layer of WSN to make a distributed feeding network...