G-REMiT: An Algorithm for BuG-REMiT: An Algorithm for Building Energy Efficient Multicailding Energy Efficient Multica

st Trees inst Trees inWireless Ad Hoc NetworksWireless Ad Hoc Networks

Bin Wang and Sandeep K. S. GuptaBin Wang and Sandeep K. S. Gupta

NCA’03NCA’03

speakerspeaker ：： Chi-Chih WuChi-Chih Wu

OutlineOutline

IntroductionIntroduction

System Module and AssumptionSystem Module and Assumption

Multicast Energy Cost Estimation

G-REMiT Protocol Details

Performance Evaluation

Conclusions

IntroductionIntroduction

Wireless ad hoc network (WANET)– myriad wirelessly connected static devices– no infrastructure

Energy efficiency is an important design consideration in WANET– serious resource (battery) constraints

IntroductionIntroduction

Multicast is an important communication primitive– Group communication– Distributed cache maintenance

Multicast tree is an efficient approach to overcome resource wastage in multicasting

System Module and AssumptionSystem Module and Assumption

AssumptionsAssumptions– Each node in the WANET has only local view

of the network– Each node knows the distance between itself

and its neighbor nodes using distance estimation schemes

– We assume that every node can know the number of nodes in the multicast group

– Average of multicast message generation rate at a given node is stable over a period time.

System Module and AssumptionSystem Module and Assumption

p p i,j i,j = E= Eelecelec + K( r + K( ri,ji,j ) )αα

– p p i,j i,j ： ： minimum power neededminimum power needed for link betwee for link between nodes i and jn nodes i and j

– EEelec elec ： ： distant-independent constant that accounts for realworld overheads of electronics and digital processing

– K ： constant dependent upon the properties of the antenna

– rri,j i,j ： Euclidean distance between i and j– α ： constant which is dependent on the

propagation losses in the medium

L. M. Feeney and M. Nilsson. ，” Investigating the energy consumption of a wireless network interface in an ad hoc networking environment”

System Module and AssumptionSystem Module and Assumption

MST (minimum weight spanning tree)MST (minimum weight spanning tree)

multicast group members

forwarding nodes

R. Gallager et al. ，” A distributed algorithm for minimum weight spanning trees”

Multicast Energy Cost Estimation

the energy cost at every tree node is not only decided by the distance between connected tree neighbors but also decided by where the message is coming fromfrom

4

1

9

3

2

10

Max(p9,1 ， p9,3 ， p9,4 ， p9,10) = p9,3

Max(p9,1 ， p9,2 ， p9,3 ， p9,4) = p9,2

Multicast Energy Cost Estimationp p i,ji,j = E = Eelecelec + K( r + K( ri,ji,j ) )αα

λi ：Message generation rate

Multicast Energy Cost Estimation

p p i,j i,j = E= Eelecelec + K( r + K( ri,ji,j ) )αα

Multicast Energy Cost Estimation

G-REMiT Protocol Details

Criterion for switchingCriterion for switching– EEelecelec = 0 = 0– αα = 2 = 2– ChangeChange22

9,69,6

– Gain (gGain (g229,69,6))

– RR22 = r = r9,29,22 2 == 22.5922.59

RR66 = r = r6,106,102 + 2 + 8 * r8 * r6,86,8

2 2 = 94.68= 94.68RR99 = r = r9,39,3

2 + 2 + 8 * r8 * r9,29,222 = 191.43 = 191.43

– RR22’’ = r = r2,62,6

2 2 = 12.96= 12.96RR66

’’ = r = r6,26,22 + 2 + 8 * r8 * r6,86,8

2 2 = 100.08= 100.08

RR99’’ = r = r9,49,4

2 + 2 + 8 * r8 * r9,39,32 2 = 93.33= 93.33

– gg229,6 9,6 = (R= (R22+R+R66+R+R99) – (R) – (R22’+R’+R66’+R’+R99’) = 102.33’) = 102.33

gg229,10 9,10 = (R= (R22+R+R99+R+R1010) – (R) – (R22’+R’+R99’+R’+R1010’) = 10.89’) = 10.89

gg229,8 9,8 = (R= (R22+R+R99+R+R88) – (R) – (R22’+R’+R99’+R’+R88’) = 44.82’) = 44.82

G-REMiT Protocol Details

Algorithm descriptionAlgorithm description– DistributedDistributed– Divided into two phasesDivided into two phases

First phaseFirst phase– Run Gallager et al. Run Gallager et al. ，” ，” A distributed algorithm for mi

nimum weight spanning trees” ， to build a MST tree– Nodes have all local information

G-REMiT Protocol Details

G-REMiT Protocol Details

Second phaseSecond phase– Depth-First Search (DFS)Depth-First Search (DFS)– TokenToken

Example 1Example 1 ：：i

x

j

Join_REQJoin REP

G-REMiT Protocol Details

Example 2Example 2 ：：

Performance EvaluationPerformance Evaluation

10, 20, 40, 60, 80, 100, 200 nodes10, 20, 40, 60, 80, 100, 200 nodes

The graph is connectedThe graph is connected

Network bandwidth is 50 kb/sNetwork bandwidth is 50 kb/s

Message generation rate is randomly geneMessage generation rate is randomly generated as 0, 1, 2, …, 50 kb/srated as 0, 1, 2, …, 50 kb/s

αα = 2 = 2

Performance EvaluationPerformance Evaluation

TPC (total power consumed)TPC (total power consumed)

MIP 、 MLiMST– J. Wieselthier et al. ，” On the construction of energ

y-efficient broadcast and multicast tree in wireless networks” ，INFOCOM 2000

Performance EvaluationPerformance Evaluation

Performance EvaluationPerformance Evaluation

ConclusionsConclusions

G-REMit algorithm to construct an energy-G-REMit algorithm to construct an energy-efficient multicast treeefficient multicast tree

G-REMit algorithm performs much better tG-REMit algorithm performs much better than most existing energy efficient multicashan most existing energy efficient multicast algorithmt algorithm

In featureIn feature ，， we plain to extends G-REMit we plain to extends G-REMit algorithm to mobile ad hoc networks and salgorithm to mobile ad hoc networks and study its performancetudy its performance