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 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 , 1995) 2Mb/s listen:receive:transmit 1:1.2:1.6W when sleeping wireless LAN 0.75:1.5:1.9W cards 0.83:1:1.4W

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