slide_residual time aware forwarding for randomly duty-cycled wsn

7/28/2019 Slide_Residual Time Aware Forwarding for Randomly Duty-Cycled WSN

1/24

Networking Laboratory1/27

Sungkyunkwan University

Copyright 2000-

2011 Networking Laboratory

Residual Time Aware Forwarding for Random ly

Duty-Cycled Wireless Sensor Netwo rks

Long Cheng, Canfeng Chen, Jian Ma, Lei Shu, and Laurence T. Yang

IEEE Conference on Computational Science and Engineering 2009

2011/11/15

Nguyen Phan Khanh Ha [email protected]


2/24


Presentat ion Outl ine

Introduction

Related Work

Overview of the scheme

Residual Time Aware routing metric

Residual Time Aware Forwarding strategy

Discussions

Performance Evaluation

Conclusion


3/24


In t roduct ion

Data delivery is a major function of sensor network

applications

To save the energy, low duty-cycle WSNs are designed and

deployed In randomly duty-cycle WSNs, sensors turn on and off in a random fashion

independent of each others

The authors propose a new routing metric as well as a

packet forwarding strategy for geographic routing in

randomly duty-cycled WSNs The objective is to increase the delivery ratio and average advance

per hop, and reduce the delivery latency introduced by the duty-

cycling operation


4/24


Related Work

Geographic routing is greedy forwarding data packets tothe neighbor geographically closest to the destination Priori forwarding method:

In [1], [2], the next-hop forwarder is selected as a priori by the

forwarding node

Each node sends periodic control messages (beacons) including itsinformation

Each node maintains neighbor tables which store information

(location, link quality) of all its neighbors

Posteriori forwarding method (on-demand contention-based forwarding):

In [3], [4], the next-hop forwarder is chosen based on the contentionamong neighbors

Neither topological knowledge or routing table are needed at each

node

The contention process is achieved by calculating a routing metric to

assign different back-off time at each neighbor


5/24


Related Work

In [3], the authors propose a posteriori forwarding method,called BOSS Data packet is sent first rather than control messages

Only neighbors who successfully receive Data packet and provide positive

advance contend to be the next forwarder

Advance refers to the decreased distance between the neighbor to thedestination comparing with the forwarding node

Each contender starts a timer whose value depends on a metric

When timer expires, it sends a Response message to the forwarding node

The forwarding node broadcasts a Selection message to announce the

contention result and the new selected forwarding node starts broadcastingData packet

f

a

b

cS

dResponse

g

h

D

dataSelection

data

In this paper, the authors apply this

packet delivery scheme to randomly

low-duty-cycle WSNs


6/24


Assumpt ions

Each sensor dynamically turns on and off its radioindependent of other sensors The sleep duration tsis uniformly distributed within [MsVs, Ms+Vs]

The wake duration tais uniformly distributed within [MaVa, Ma+Va]

Mand Vare the mean value and the variance respectively

Each node only knows its current wake/sleep schedule, e.g.,

the residual time when in awake state Residual time Trrefers to the remaining time of a node keeping awake state

in its schedule

Each node can send and receive when it is in awake state

Ms Vs Ma Va

Duty

cycle

4 (s) 2 (s) 1(s)0.5(s)

20 %

ta

[0.5,1.5]; ts

[2,6]


7/24 Networking Laboratory7/23

Motivat ion

Existing routing metrics for geographic routing, e.g.maximum-advance are not suitable for randomly duty-

cycled WSNs Among neighbors of forwarding node S, A wins the contention and become

the next-hop forwarder of node S

A broadcasts Data packetto its neighbors A turns off the radio before receiving response message from its best next-

hop forwarder candidate Cbecause ofits limited residual time -> The three-

way handshake transmission fails ->A has to retransmit Data packet in the

next awake state

B should take the forwarding responsibility since it has longer residual time



Overv iew of the scheme

An appropriate routing metric is needed in the contentionphase to help the forwarding node make a foresighted next

hop forwarder selection in duty-cycled networks

The authors propose a residual time aware (RTA) routing metric

RTA metric assigns the priority for each contender based on an overall

consideration including the advance distance and the residual time

of both the forwarding node and the contender

A RTA forwarding strategy is presented using the RTA metric for

data forwarding in duty-cycled networks

A

B

C

S D

Forwarding node Destination

Dist(S,D)



Residual Time Aware Rout ing Metr icNotat ion

Tr(i): The current residual time of node i keeping in theawake state

Tmax: A predefined value, the upper bound for setting the

maximum value of contention timer of a contender

Tmax(j): The maximum value of nodejs contention timer To avoid the three way handshake transmission fails, the Response

message should be replied before the forwarding node turns off its

radio )('max

)(

max ,mini

r

j TTT



Residual Time Aware Rout ing Metr icPrior i ty As signment (1/2)

For each contenderj, the contention timers value ofj, Tset(j)

ADV(i,j): The advance provided by node j when j forwards data sent from

forwarding node i, ADV(i,j) = Dist(i,dest) Dist(j,dest)

R: The transmission range of a node

Tmax(j): The maximum value of nodejs contention timer

: the modification coefficient by taking the residual time of node j into

consideration

,0),(

1 )(max)( randomT

R

jiADVT jjset

Tset(j) < Tset

(k) : contender

j is selected as the next

hop forwarder of node i

i

Contenderk

Contenderj

Destination

Dist(i,dest)



Residual Time Aware Rout ing Metr icPrior i ty As signment (2/2)

: the modification coefficient by taking the residual time of node j intoconsideration

: the roughly estimated contention time needed by

contenderj

Tmax : the upper bound for setting the maximum value of contention

timer (In advance for node jssubsequent forwarding process)

The contender which provides more advance and has longer

residual time is assigned higher priority (lower value ofTset)

,0),(

1 )(ma x)( randomT

R

jiADVT jjset

1,),(

1

min'

max

)(

ma x

)(

TTR

jiADV

T

j

j

r

)(

ma x

),(1

jT

R

jiADV

i

Contenderk

Contenderj

Destination

l



Residual Time Aware Forw arding

A forwarding node i Broadcast Data packet and waits in a maximum time for the

Response messages

If not receive Response message, rebroadcast Data packet up to K1

times

If receive the first Response message, broadcast Selection messagecontaining the ID of selected contender and wait for the implicit ACK

If fail to receive ACK, rebroadcast Selection message up to K2times

If overhear ACK, go back to monitoring state and wait to receive

otherData packets

A neighborjof node i Once receiving a Data packet, start its contention timerTset

(j)

When the timer Tset(j) expires, it sends a Response message to the

forwarding node i, waits for the Selection message and continues forwarding

data

The Selection message will suppress otherneighbors contention

)('ma x ,min irTTT



Residual Time Aware Forw ardingExample

data

Tr(i )

j

m

l

ik

D

Tset(j )

Tset(l )

Tset(k )

Response

Selection

data

Data

Response message

Selection message

Tr(j )

Tr(k )

Tr(l )



Discu ss ion (1/3)

The Response message from the best neighbor (theneighbor with the smallest contention time Tset) can be lost

The forwarding node i selects the neighbor which its Response

message reaching node iearliest as the next-hop forwarder

RTAF strategy cannot guarantee selecting the best neighbor in

terms of RTA routing metric

Data

Tr(i )

j

i k D

Tset(j )

Tset(k )

Response message

Selection message



Discu ss ion (2/3)

Forwarding node ihas to rebroadcast Selection message incase: The transmission of previous Selection message succeeds but the

forwarding node i fails in receiving the implicit ACK from the next-hop

forwarder

Data packet is broadcasted by node is next hop forwarder servers asan implicit ACK

j

i k D

Data

Data broadcasted

by nodej(Implicit ACK)

Selection

(Node j)...

...

...

wakewakesleep sleep

sleep sleep

wake

Response message

Data packet

Selection message



Discu ss ion (3/3)

Forwarding node ihas to rebroadcast Selection message incase: The transmission of previous Selection message failed

Residual timeResidual time is smaller

sleep

sleep

sleep

sleep

wake wake

wake

j

i k D

Response message

Data packet

Selection message

Selection node j

Selection node j



Performance Evaluat ionSimulat ion setup

Using NS-2 simulator Comparing the result with Maximum-advance forwarding (MAF)

scheme

Using the packet delivery scheme like RTAF but using maximum-

advance distance as routing metric

400 sensors are uniformly placed in a 200mx200m field

The upper bound of the contention timer are Tmax= 0.5s and 1s

The average wake/sleep schedule period is set 5s

The sleep duration of each sensor:

ts[2.25,6.75]

The active duration of each sensor:

ta[0.25,0.75]



Performance Evaluat ionEvaluat ion metr ics

Advance per hop:

The ratio ofthe sum of one-hop advances to the number of hops

End-to-end hops:

The number ofrequired hops for an end to end transmission

End-to-end delivery delay:

The time for transmitting a data packet from a source to the sink

Duty-cycling Introduced delay:

The delayed time caused by the duty-cycling operation for an end-

to-end transmission

Duty-cycling Introduced delay ratio:

Data delivery ratio

DelayDeliveryendtoEnd

DelayIntroducedcyclingDuty



Performance Evaluat ionImpact of Duty-cyc le

RTAF improves the end-to-end delay compared with MAF

The duty-cycling introduced delay ratio of RATF decreasesmore rapidly when the duty-cycle increases

At lower duty cycles, RATF has the higher delivery ratio

than MAF



Performance Evaluat ionImpact of no de densi ty

Node duty cycle is 15%, Tmax= 0.5 s

RATF reduces the performance degradation caused by theduty-cycle operation such as retransmission, delay

introduced by duty-cycling



Conclus ion

A new residual time aware routing metric for randomly duty-

cycled WSNs which is more responsive to the dynamics

resulting from the uncertainty ofnodes sleep scheduling is

proposed

There are some problems with the residual time aware

forwarding strategy using the proposed RTA metric



References

[1] Y. Yu, R. Govindan, and D. Estrin, Geographical and energy aware

routing: a recursive data dissemination,Technical Report UCLA/CSD-

TR-01-0023, UCLA Computer Science Department, 2001

[2] K. Seada, M. Zuniga, A. Helmy, and B. Krishnamachari, Energy-

efficient forwarding strategies for geographic routing in lossy wirelesssensornetworks, in Proc. ACM SenSys 04, pp. 108121, 2004

[3] J. Sanchez, R. Marin-Perez, and P. Ruiz, BOSS: Beacon-less on

demand strategy for geographic routing in wireless sensornetworks, in

Proc. IEEE MASS 07, pp. 110, 2007

[4] H. F., J. Widmer, M. M. Michael Ksemann, and H. Hartenstein,Contention-based forwarding for mobile ad-hoc networks, Elseviers

Ad Hoc Networks, vol. 1, no. 4, pp. 351369, 2003


23/24


Thank you for your listening!


24/24

N ki L b 24/23

Example

Tr(S)

= 0.75; Tr(A)

= 0.5; Tr(B)

= 0.25 Assume Tmax

= 0.5 s

Tmax(A) = Tmax

(B)= min(Tr(S) , Tmax

) =

0.5 s

NodeA:

ADV(S,A) = 15-6 = 9

Node B:

ADV(S,B) = 15-8 = 7

Ms

Vs Ma Va

Duty

cycle

4.25

s

2.125

s

0.75

s

0.375s

15 %

ts [2.125,6.375]; ts [0.375,1.125]

Forwarding node S

Active time: 1 s; Sleep time: 3 s

Dist(S,dest)=15

R = 10

NodeA

Active time: 1 s;

Sleep time: 2.75 s Dist(A,dest)=6

Node B

Active time: 0.5 s;

Sleep time: 3 s

Dist(B,dest)=8

11

101,

5.05.010

91

5.0min1,

),(1

min'

max

)(

max

)(

TTR

ASADV

T

j

A

rA

09.0,0),(

1 )(max)(

randomT

R

ASADVT AA

A

set

385.01,

5.05.010

71

25.0min1,

),(1

min'

max

)(

max

)(

TTR

BSADV

T

j

B

rB

365.0,0),(

1 )(max)(

randomT

R

BSADVT BB

B

set

slide_residual time aware forwarding for randomly duty-cycled wsn

Documents