Concurrent Sidelobe Minimization and Node Transmission Power Reduction in Collaborative Beamforming in Wireless Sensor Networks

Abstract

Collaborative Beamforming (CBF) is an essential tool towards increasing transmission range in Wireless Sensor Networks (WSNs). Conventional CBF (essentially beamsteering) is intricately associated with high sidelobes owing to the usual random WSN node arrangement. In WSNs high sidelobes imply increased interference at co-channel data sinks. This necessitates adoption of sidelobe minimization procedures in CBF. Also, WSN sensor nodes bear limited energy resources necessitating apt power control during CBF. Current literature focuses on peak sidelobe minimization upon conventional beamsteering; This yields sub-optimal outcomes. Power control during CBF has not been intricately addressed in current literature. In this paper, a novel approach towards concurrent beam- steering, generalized sidelobe minimization and node transmission power reduction is proposed. The proposed scheme simultaneously adjusts collaborating nodes’ transmission phase and amplitude to ensure the intended multiple objectives are met. Firefly Algorithm (FA) is utilized in optimizing the nodes’ transmission phase and amplitude. Performance comparisons have been carried out against a scheme featuring concurrent beamsteering and generalized sidelobe minimization only (without node transmission power control). The overall performance has been validated against a peak sidelobe minimization approach (as per the current literature). The proposed scheme is noted to improve node transmission power and overall sidelobe performance whilst maintaining appreciable beamsteering accuracy. Keywords—Wireless Sensor Network, Collaborative Beamforming, Sidelobes, Firefly Algorithm