DocumentCode :
818193
Title :
Distributed Adaptive Quantization for Wireless Sensor Networks: From Delta Modulation to Maximum Likelihood
Author :
Fang, Jun ; Li, Hongbin
Author_Institution :
Dept. of Electr. & Comput. Eng., Stevens Inst. of Technol., Hoboken, NJ
Volume :
56
Issue :
10
fYear :
2008
Firstpage :
5246
Lastpage :
5257
Abstract :
We consider distributed parameter estimation using quantized observations in wireless sensor networks (WSNs) where, due to bandwidth constraint, each sensor quantizes its local observation into one bit of information. A conventional fixed quantization (FQ) approach, which employs a fixed threshold for all sensors, incurs an estimation error growing exponentially with the difference between the threshold and the unknown parameter to be estimated. To address this difficulty, we propose a distributed adaptive quantization (AQ) approach, which, with sensors sequentially broadcasting their quantized data, allows each sensor to adaptively adjust its quantization threshold. Three AQ schemes are presented: (1) AQ-FS that involves distributed delta modulation (DM) with a fixed stepsize, (2) AQ-VS that employs DM with a variable stepsize, and (3) AQ-ML that adjusts the threshold through a maximum likelihood (ML) estimation process. The ML estimators associated with the three AQ schemes are developed and their corresponding Cramer-Rao bounds (CRBs) are analyzed. We show that our 1-bit AQ approach is asymptotically optimum, yielding an asymptotic CRB that is only pi/2 times that of the clairvoyant sample-mean estimator using unquantized observations.
Keywords :
delta modulation; maximum likelihood estimation; quantisation (signal); wireless sensor networks; Cramer-Rao bounds; bandwidth constraint; delta modulation; distributed adaptive quantization; distributed parameter estimation; maximum likelihood estimaton; wireless sensor networks; Adaptive quantization (AQ); distributed estimation; wireless sensor networks (WSNs);
fLanguage :
English
Journal_Title :
Signal Processing, IEEE Transactions on
Publisher :
ieee
ISSN :
1053-587X
Type :
jour
DOI :
10.1109/TSP.2008.928956
Filename :
4579689
Link To Document :
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