Minimum Energy Decentralized Estimation in a Wireless Sensor Network with Correlated Sensor Noises
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Minimum Energy Decentralized Estimation in a Wireless Sensor Network with Correlated Sensor Noises Alexey Krasnopeev Department of Electrical and Computer Engineering, University of Minnesota, 200 Union Street SE, Minneapolis, MN 55455, USA Email: [email protected]
Jin-Jun Xiao Department of Electrical and Computer Engineering, University of Minnesota, 200 Union Street SE, Minneapolis, MN 55455, USA Email: [email protected]
Zhi-Quan Luo Department of Electrical and Computer Engineering, University of Minnesota, 200 Union Street SE, Minneapolis, MN 55455, USA Email: [email protected] Received 25 November 2004; Revised 20 May 2005 Consider the problem of estimating an unknown parameter by a sensor network with a fusion center (FC). Sensor observations are corrupted by additive noises with an arbitrary spatial correlation. Due to bandwidth and energy limitation, each sensor is only able to transmit a finite number of bits to the FC, while the latter must combine the received bits to estimate the unknown parameter. We require the decentralized estimator to have a mean-squared error (MSE) that is within a constant factor to that of the best linear unbiased estimator (BLUE). We minimize the total sensor transmitted energy by selecting sensor quantization levels using the knowledge of noise covariance matrix while meeting the target MSE requirement. Computer simulations show that our designs can achieve energy savings up to 70% when compared to the uniform quantization strategy whereby each sensor generates the same number of bits, irrespective of the quality of its observation and the condition of its channel to the FC. Keywords and phrases: wireless sensor networks, decentralized estimation, power control, energy efficiency.
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INTRODUCTION
Wireless sensor networks (WSNs) are ideal for environmental monitoring applications because of their low implementation cost, agility, and robustness to sensor failures. A popular WSN architecture consists of a fusion center (FC) and a large number of spatially distributed sensors. The FC can be either a standard base station or a mobile access point such as an unmanned aerial vehicle hovering over the sensor field. Each sensor in a WSN is responsible for local data collection as well as occasional transmission of a summary of its observations to the FC via a wireless link. In a practical WSN, each sensor has only limited computation and communication capabilities due to various design considerations such as small size battery, bandwidth, and cost. As a result, it is difficult for sensors to send their entire real-valued observations This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
to the FC. Instead, a more practical decentralized estimation scheme is to let each sensor quantize its real-valued local measurement to an appropriate length and send the resulting discrete message (typically short) to the FC, while the latter comb
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