後卓越進度報告 蔡育仁老師實驗室 2007/06/04

DSC with Slotted ALOHA Random Access Distributed source coding (DSC) We study the effect of MACs on the efficiency (delivery success rate ) and delay of DSC-based sensor network Encoder 1 Encoder 2 Joint Decoder X Y X, Y : Sensor : cluster head Number of reconstructed packets N Success Rate  Delay : the average number of time slots needed to reconstruct Node 1 23 N p1p1 p2p2 p3p3 pNpN

Energy Consumption Analysis Energy consumption for slotted ALOHA in a DSC-based WSN has been analyzed in two point-of-views: Average energy consumed to resolve at least n packets Average energy consumption after m slots transmissions Comparisons are made among transmission schemes with different transmit probability sets { p 1, p 2, …, p N } Node i i p i p i p Scheme 1Scheme 2 Scheme 3

Simulation Model for H (X i | X i-1,…, X 1 ) Consider {X i } as a 1-D continuous-space-parameter stationary Gaussian-Markov process [1] with Zero mean, variance σ 2 Autocorrelation : R (τ) = σ 2 e – |τ| ( τ is a distance factor) Based on above model, the conditional entropy is given as [1] E.g., for σ = 1,

Time Slot Entropy Scheme 3 Scheme 1 Scheme 2 Average Entropy Transmitted vs. Time Slots

Reference [1] D. Marco and D. L. Neuhoff, “Reliability vs. efficiency in distributed source coding for field-gathering sensor networks,” IPSN 2004, pp