PIES: Protocol Independent Energy Saving Algorithm

	Yasser Gadallah
	Thomas Kunz
	August 15, 2004

Presentation Outline

	Energy Consumption in Mobile Ad Hoc Networks
	Proposed Solution: PIES
	PIES Evaluation
	Conclusions

Energy Consumption In Mobile Ad Hoc Networks

	Many sources of energy consumption exist in mobile nodes e.g. screens, HDD, interfaces, etc
	Our focus is energy consumed in wireless interfaces
	Energy is consumed in sending, receiving, idle and sleep modes of operation
	It is crucial for energy conservation that we eliminate or reduce wasted idle energy consumption which constitutes a large portion of energy consumption is wireless interfaces
	To do this, ideally nodes need to be put to sleep when idle to save this wasted energy

Proposed Solution: PIES - Goals

	Fair energy conservation: all nodes are treated equally
	Complements existing routing algorithms from energy conservation perspective
	Functionality that is independent of the underlying routing protocol
	Little or no impact on network operation – no additional major traffic

Proposed Solution: PIES - Characteristics

	Achieves fair energy conservation by:
		Putting nodes to sleep for equal time periods
		Providing the routing algorithm with energy threshold info to help it make fair energy conscious decisions
	Fully distributed algorithm – functionality does not depend on a node or a set of nodes
	Modular nature – easily integrated with existing routing algorithms
	Ability to determine with certainty neighbors’ sleep state
	Configurable in such a way that introduces no additional traffic to the network

PIES Evaluation – Energy Performance

PIES Evaluation – Packet Delivery Performance

PIES Evaluation – Summary

	PIES introduces energy savings of about 50% for the conditions we used
	It also extends network lifetime by about 70%
	This is done while achieving higher fairness than in the case of the routing protocol alone
	The resulting PDR is comparable to that of the routing protocol alone
	Packet delivery latency increases with the increase of the ST/WT ratio

Conclusions

	Energy is the most scarce resource for the functionality of mobile ad hoc networks
	PIES is a solution that achieves fair energy conservation and works with existing routing algorithms
	Simulations show that PIES achieves energy savings of about 50% and extends network lifetime by about 70%

Backup Slides

Ad Hoc Network Energy Management Issues – Energy Conservation Challenges

	Energy conservation mechanisms should not add significant energy consumption or traffic demands on the network
	It should be able to answer the following questions:
		When to put the node to sleep without knowledge of traffic patterns?
		When to wake the node up?
		What is the sleep state of a neighbor?
		If the neighbor is asleep when will it wake up?
	There should be no major effect on the normal network functionality (e.g. no major traffic loss)

Energy-Efficient Schemes - Issues

	Most routing energy-efficient schemes ignored idle energy consumption in their analysis
	Non-routing energy-efficient schemes suffered one or more of the following issues:
		No attention given to energy fairness among network nodes
		Unrealistic assumptions e.g. traffic nodes do not forward traffic
		Algorithm design tied to a specific underlying routing strategy
		Large impact on the functionality of the underlying routing scheme
		No interaction with underlying routing protocol which results in unnecessary loss of traffic
		Heuristic methodology in determining neighbors’ sleep state

Proposed Solution: PIES - Operation