Distributed beamforming using semiblind retracement technique for randomly distributed sensors

Abstract

Beamforming technique is being used in sensor networks to enhance its communication range. The sensors in a networks work on their own clock and for distributed beamforming these signals coherently add at the destination. For this, the knowledge of the channel state information is required. Since the channel state information (CSI) is not available at the transmitter side, the retracement technique is used to estimate the channel effect. In this paper, a novel Semiblind retracement technique is proposed to improve the data transfer rate. The semiblind retracement technique is considered for the cases of a 1 bit feedback and for no reliable feedback mechanism from destination. The sensor distribution is considered as uniform and gaussian and the channel is modeled as Rayleigh and Rician distributed. Simulation results indicate that the proposed semiblind method results in improved data rate. The efficiency is about 9.1% increase in data transmission rate for the worst case channel variation assuming retracement slot is 20% of transmission slot and with 3dB reduction in gain.