Opportunity-based Topology Control in Wireless Sensor Networks

Date: 2009.12.30Speaker: Chang, Chien-Yang

IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS ||||

Outline Introduction Related Work System Model CONREAP Performance Evaluation Conclusion

Introduction Topology control is an effective method to improve the energy efficiency of wireless sensor networks (WSNs)

connectivity-based topology control reliable links

opportunity-based topology control lossy link reliable links

Related Work Connectivity-based topology control Cone-Based Topology Control (CBTC)

System Model Assumptions

individual link reachability is available the link reachability is fixed the link reach ability is pretty stable (not asymmetric) the node is stationary only sink-to-sensors communications

Without consideration do not consider the node failure no node sleeping is considered in this work. no congestion or packet collision is considered either.

Motivation

Problems Reachability Preserving Problem ( RPP)

data-critical applications to minimize the energy cost while guaranteeing that the network reachability is no less than a given threshold

Energy Preserving Problem long-term monitoring to maximize the network reachability while guaranteeing that the network energy cost is no greater than a given threshold

Efficiency Maximization Problem no constraint on energy or network reachability to maximize the reachability-energy ratio

Basic Idea Reachability Preserving Problem

Greedy algorithm

CONREAP Initially, v broadcasts a “Hello” message and initials its neighbor set Nbv

CONREAP Step2. from the known λTi (u), v selects a node ui that provides v the highest tree reachability λTi (v) as its parent node in the tree

0.80.4

0.2

0.9

CONREAP Step3. node v selects the tree with the highest λTi (v) to join,

denoted as

and

CONREAP Step4. Upon receiving the Nbv node reachability, v updates avg(˜λGR(v))

Until

Performance Evaluation Experiment parameters

50 Berkeley Mica2 nodes uniformly deployed transmission power: -10dbm maximal distance: 5 hops link reachability is measured using 1000 “Hello” messages receivers continuously measure the link quality and piggyback the results to senders

Performance Evaluation Experiment results

Performance Evaluation Simulation parameters

evaluate CONREAP in a large scale of 200 nodes fixed-size field of 300m × 300m 1/9 of the simulated wireless links are reliable the other 8/9 are lossy links

Performance Evaluation Simulation results

Conclusion We propose a novel opportunity-based topology control We focus on the reachability preserving problem

this problem is NP-hard we propose CONREAP algorithm by exploring reliability theory we prove that CONREAP has the guaranteed network reachability and the energy cost can be significantly reduced the worst running time is O(|E|) and the space requirement is O(d)