Wireless sensor networks consisting of large numbers of inexpensive energy-constrained nodes are an area of emerging networking research. Routing algorithms in these networks are required to provide tolerance to temporary or lasting faults. In this paper, the authors show a single path routing scheme with higher transmit power to be an energy-efficient solution for robustness to node failures, in terms of energy-efficiency.
WSNs consisting og large numbers of in-expensive energy-constrained devices are expected to find a wide range of applications from vehicle tracking to habitat monitoring.
There are many research on multipath routing in mobile ad-hoc networks (MANETs), the basic idea behind multipath routing is fault-tolerance through redundancy, An alternative philosophy for fault tolerance is to minimize the number of failure modes by reducing the number of intermediate nodes prone to failure. In sensor networks this can be done even with single-path routing algorithms utilizing higher transmission ranges.
They begin exploration of the energy-robustness tradeoff by considering a simple, small configuration of five sensor nodes.
Each configuration represents a possible way to route information from the source to the receiver. If we assume that nodes can only communicate with other nodes within a common radius R, then there is a minimum radius required for each routing configuration to be possible.
They assume that the energy required to transmit on a link is R^α , where the path loss exponent α is typically between 2 to 5 (for dense networking situations it is closer to 2)
They define an energy metric for each routing scheme H as follows : if the minimum common transmission radius required for it is RH, and mH transmission are required, then the energy cost for the scheme H is considered to be mHRH^α.
The robustness metric ΠH corresponding to the routing scheme H is the probability that a message sent from the source can reach the sink given these independent failure probabilities.
Pareto optimality :
A routing scheme Hi is said to dominate a routing scheme Hj if it results in an equal or greater robustness level with strictly less energy cost or if it results in an equal or lesser energy cost with strictly higher robustness level, or if ΠHi >= ΠHj; EHi < EHj, or if EHi <= EHj ; ΠHi > ΠHj.
Routing schemes which are not dominated by others in the set of considered schemes are said to be Pareto optimal and constitute the Pareto set.
Experimental Setup :
they use 50 nodes are placed in a square area with unit sides. The source is placed at (0;0), and the destination sink node is placed at (1;1). The simulation is repeated 100 times with random placements for the remaining 48 intermediate nodes. For each simulation the transmission radius R within which each pair of nodes can communicate is increased in increments of 0.05 from 0.05 to 1.5. Th authors use forward-k routing algorithms.
Let see original paper for more detail 🙂
The Energy-Robustness Tradeoff for routing in Wireless Sensor Networks
Bhaskar Krishnamachari et all
University of southern California.
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February 12 2008,
High Speed Network Lab