Geography-informed Energy Conservation for Ad Hoc Routing by RG

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									Geography-informed Energy Conservation for Ad Hoc Routing
Ya Xu, John Heidemann, Deborah Estrin ISI & UCLA
Presented by: Cristian Borcea

Motivation



reduce the energy consumption in ad hoc wireless networks


increase the network lifetime

Solution



identifies equivalent nodes for routing


based on location information



turns off unnecessary nodes

Assumptions
dense node deployment




many nodes can hear each other



each node knows its location


GPS ... but better other methods

Energy Model


listen:receive:transmit energy consumption


1:1.05:1.4 or 1:1.2:1.7



recall from last week
 

listen:receive:transmit times are 1:3:40 duty cycle > 22% ==> more than 50% of energy spent in listening



energy dissipation in idle state cannot be ignored

Effects of turning radio off in the idle state

Determining Node Equivalence






the physical space is divided into equal size squares  based on nominal radio range any two nodes in adjacent squares can communicate with each other the nodes within a square are equivalent

Geographical Adaptive Fidelity ( GAF ) Routing


nodes in the same grid coordinate each other


who will sleep and for how long



runs over any ad hoc routing protocol



load balancing energy usage


all nodes remain up for us long as possible

GAF state transitions

Node Ranking


node(active) > node(discovery) enat1>enat2 ==> node(enat1)> node(enat2)




enat = estimated node active time



node ids break the ties

Adapting to Mobility


each node estimates the time when it expects the leave the grid: engt includes this estimation in the discovery message




other nodes sleep for min(enat, engt)



GAF-ma ( mobility adaptation ), GAF-b ( basic scheme )

Simulation


ns2 + cmu's extension for 802.11


   

AODV vs GAF/AODV
DSR vs GAF/DSR 50 transit nodes ( "routers" ) 10 traffic nodes ( sources & sinks ) Traffic: CBR



Nominal radio range: 250

Energy model - values used in simulation


WaveLAN (pre-802.11, 1995) 2Mb/s



listen:receive:transmit 1:1.2:1.6W


0.025 when sleeping 0.75:1.5:1.9W 0.83:1:1.4W



802.11 wireless LAN
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

802.11 cards


Network Lifetime

GAF energy savings


mean energy consumption per node (E0-Et)/(n*t)


E0 initial total energy for n nodes Et total energy after time t





results: GAF+AODV is 40% better than AODV


for both GAF-b, GAF-ma

GAF-b vs GAF-ma

Data Delivery Ratio

Average Delay

Network lifetime: GAF vs AODV

Network Lifetime vs Node Density

Conclusions

 

GAF increases the network lifetime does not decrease the performance

substantially


								
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