Asymptotic analysis of cooperative censoring policies in sensor networks

TL;DR

The problem of cooperative data censoring in battery-powered multihop sensor networks is analyzed, and a theoretically optimal censoring policy, which maximizes a long-term reward, is found.

Abstract

The problem of cooperative data censoring in battery-powered multihop sensor networks is analyzed in this paper. We are interested in scenarios where nodes generate messages (which are related to the sensor measurements) that can be graded with some importance value. Less important messages can be censored in order to save energy for later communications. The problem is modeled using a joint Markov Decision Process of the whole network dynamics, and a theoretically optimal censoring policy, which maximizes a long-term reward, is found. Though the optimal censoring rules are computationally prohibitive, our analysis suggests that, under some conditions, they can be approximated by a finite collection of constant-threshold rules. A centralized algorithm for the computation of these thresholds is proposed. The experimental simulations show that cooperative censoring policies are energy-efficient, and outperform other non-cooperative schemes.

Figures (10)

• Figure 1: Threshold functions for a network of 2 nodes (plus the sink) in a line topology. (a) Optimal threshold function at node 1, $\mu_1({\bf e})=\mu({\bf e},1)$ for a non-rechargeable node with ${\bf c}_0(1) = (3,1)^\top$, ${\bf c}_0(2) = (1,3)^\top$, ${\bf c}_1(1) = (11,10)^\top$, ${\bf c}_1(2) = (1,10)^\top$. (b) Optimal threshold function at node 2, $\mu_2({\bf e})=\mu({\bf e},2)$.
• Figure 2: The value function $\lambda(e)$ for a network of 2 nodes in a line topology for the optimal threshold functions calculated in Fig.\ref{['fig:MuExp']}.
• Figure 3: (a) Asymptotic threshold for the 2-node network described in Section \ref{['Sec:CEC']}. (b) Lifetime of nodes. Direction $\phi$ is counter-clockwise measured in radians from the origin ${\bf e}=(0,0)$.
• Figure 4: Sketch for the computation of the node thresholds.
• Figure 5: Received importance sum at the sink in a line network composed of 10 nodes.