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
0
100
200
300
400
500
0 0.2 0.4 0.6 0.8 1mobility fraction (F)
tota
l ove
rhea
d in
pac
kets
(100
0s)..
.
AODVSPR
SHARP-PO: minimal packet overhead
600 nodes, single destination, 5 sources
0
100
200
300
400
500
0 0.2 0.4 0.6 0.8 1mobility fraction (F)
tota
l ove
rhea
d in
pac
kets
(100
0s)..
.
AODVSHARP-POSPR
packet overhead600 nodes, single destination, 5 sources
0
100
200
300
400
500
AODV 1 2 3 4 5 6 7 8 9 10 11 12 13 SPRzone radius
tota
l ove
rhea
d in
pac
kets
(100
0s)..
. F 0.0F 0.2F 0.4F 0.6F 0.8F 1.0
loss rate600 nodes, single destination, 5 sources
0%
5%
10%
15%
20%
25%
30%
35%
40%
0 0.2 0.4 0.6 0.8 1mobility fraction (F)
loss
rate
(%)
AODVSPR
SHARP-LR: target loss rate (5%)600 nodes, single destination, 5 sources
0%
5%
10%
15%
20%
25%
30%
35%
40%
0 0.2 0.4 0.6 0.8 1mobility fraction (F)
loss
rate
(%)
AODVSHARP-LRSPR
SHARP-LR: packet overhead600 nodes, single destination, 5 sources
0
100
200
300
400
500
0 0.2 0.4 0.6 0.8 1mobility fraction (F)
tota
l ove
rhea
d in
pac
kets
(100
0s)..
.
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