Sharp Hybrid Adaptive Routing Protocol for Mobile Ad Hoc Networks

Venugopalan Ramasubramanian (Rama)Zygmunt HaasEmin Gün Sirer

Cornell University

introductionproactive

constant high overhead independent of data trafficproactive maintenance enables low delay and often low loss rate

reactiveon-demand routing enables overhead to scale with data trafficperformance significantly affected by mobility

one protocol may out perform the other in different network conditionschange is the only constant in mobile ad hoc networks

sharp overviewhybridization framework

combine proactive and reactive routingapplication specific goals

destination nodes independently choose adaptation goals minimal packet overhead, target loss rate, target delay

jitteradaptability

fine grain adaptation to changing network and traffic characteristics

self-tuning and driven by analytical model efficiency

low overhead localized mechanisms

sharp hybrid adaptive routing

destinationsource

sharp hybrid adaptive routing

destinationsource

sharp hybrid adaptive routing

destinationsource

sharp hybrid adaptive routing

destinationsourceSPR

AODV

sharp proactive routing (SPR)destination rooted Directed Acyclic Graph (DAG)

multi-link routing DAG construction

local broadcast (TTL = zone radius) periodic reconstructions

DAG maintenance link orientation reversal (TORA) periodic update beacons

sharp proactive routingexpanding radius from r to s (r < s)

reconstruct DAG with zone radius s and TTL sshrinking radius from r to s (r > s)

reconstruct DAG with zone radius s and TTL r distributed coordination and reliable packet delivery

not requiredmultiple destinations apply SPR independently

overlapping regions share overhead

overhead of sharp routing components

proactive routingindependent of number of sources (S)largely independent of mobility (λ: mean link lifetime)depends on zone radius (r)depends on number of nodes in proactive zone (ND

r)

reactive routingdependent on number of active routes (sources and destinations)dependent on mobilitydepends on distance (h-r)depends on number of nodes in the search area (NS

h-r)

SDr h-r

h

AODVSPR

sharp adaptationestimating mean link-lifetime and mean node degree

aggregated within proactive zone piggy-backed on update beacons

estimating traffic characteristics number of sources, routing distance, loss rate, delay jitter measured at destination with information piggy-backed

on data packets by the sourceperiodically choose radius before reconstruction

driven by analytical modelhysteresis

different low and high watermarks prevents oscillations

sharp protocolsminimal packet overhead (SHARP-PO)

power and bandwidth constrained networks estimate overhead during each reconstruction

interval and adjust radiustargeted loss rate (SHARP-LR)

loss sensitive applications (TCP) incur less overhead to achieve the target loss rate

targeted delay jitter (SHARP-DJ) multi-media applications incur less overhead to achieve the target delay jitter

each destination independently chooses adaptation strategy

evaluationGloMoSim simulatorlower layers

MAC: IEEE 802.11b; range: 250m; data rate: 11Mbpsmobility

random waypoint, 0 to 20 m/s, 0 pause time mobility fraction: fraction of mobile nodes

scale 600 nodes 3000m x 3000m, 2 pkts/sec 200 nodes 1700m x 1700m, 8 pkts/sec

traffic single destination multiple destinations: 1, 4, 7, 10 sources respectively all nodes destination

packet overhead600 nodes, single destination, 5 sources

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AODVSPR

SHARP-PO: minimal packet overhead

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AODVSHARP-POSPR

packet overhead600 nodes, single destination, 5 sources

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AODV 1 2 3 4 5 6 7 8 9 10 11 12 13 SPRzone radius

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loss rate600 nodes, single destination, 5 sources

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loss

rate

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AODVSPR

SHARP-LR: target loss rate (5%)600 nodes, single destination, 5 sources

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loss

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AODVSHARP-LRSPR

SHARP-LR: packet overhead600 nodes, single destination, 5 sources

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AODVSHARP-LRSPR

conclusionsSHARP hybridization

explore the continuum between proactive and reactive routing strategies

application specific performance metrics minimal packet overhead, target loss rate, target delay

jitter nodes independently choose adaptation goals

SHARP adaptability fine grain control of hybridization across wide range of

network and traffic scenarios expensive mechanisms – clock synchronization, leader

election, agreement – not required

SHARP vs ZRPSHARP supports application specific adaptation strategies (loss rate, delay jitter) in addition to packet overhead

ZRP optimizes only for packet overheadSHARP constructs proactive zones only around destination-nodes

proactive zones around all nodes in ZRPSHARP’s proactive routing has lower overhead – only maintains routes to the center node

ZRP ‘s proactive routing is expensive – maintain multi-cast tree to the edge nodes

SHARP expands proactive zone in response to link failures, whereas ZRP shrinks the proactive zone