Staffetta: Smart Duty-Cycling for Opportunistic Data Collection

1Challenge the future

STAFFETTA: exploit duty-cycling for opportunistic data collection

M.Cattani, A.Loukas, M.Zimmerling, M.Zuniga, K.Langendoen


Data collection in WSN:problem statement

senderreceiver

rendezvous time

Sink is a special node that collect all information and has no resource constraintsNodes deliver their data to the sink over a multi-hop path and are battery powered à duty cycle their radioDuty cycle makes communication expensive due to the time and energy required by nodes to rendezvous

Collect data from a wireless network as fast as possible under severe resource constraints


Data collection in WSN:existing solutions

Choose as forwarder the closest node to the sink (shortest path)

Not always the fastest route

Best paths are over-used

Tree-based routing(unicast primitive) next-hop



From a set of best forwarders, choose the first one to wake up (fastest path)

Not always the shortest route

Robustness due to path diversity

Opportunistic routing(anycast primitive)forwarder set



Choose as forwarder the closest node to the sink (shortest path)

Not always the fastest route

Best paths are over-used

Tree-based routing(unicast primitive)

From a set of best forwarders, choose the first one to wake up (fastest path)

Not always the shortest route

Robustness due to path diversity

Opportunistic routing(anycast primitive)


Data collection in WSN:Staffetta’s idea

Bias opportunistic choices towards nodes closer to the sink (fast choices are also the shortest)



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tree-based opportunistic opportunistic with staffetta

rendezvous timerendezvous time rendezvous time


can take time to reach best forwarder



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the more forwarders, the faster (but longer paths)



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the more active, the faster the forwarding


MECHANISMStaffetta’s


Staffetta mechanism

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1) Exploit relation between the activity of nodes and rendezvous time to create a gradientsink


Staffetta mechanism

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1) Exploit relation between the activity of nodes and rendezvous time to create a gradient2) Use Activity Gradient to improve the efficiency of opportunistic data collection protocols


How to create an activity gradient

a) Give to nodes a fixed energy budget (DCmax)

b) Let nodes wake up as frequently as possible

c) In the presence of a sink, obtain an activity gradient

1) Exploit relation between the activity of nodes and rendezvous time to create a gradient


0 5

10 15 20 25 30

Wake

up F

req. [H

z]

Without Staffetta With Staffetta

0

30

60

90

120

150

Fw

d. dela

y [m

s]

Rendezvous w/o Staffetta Rendezvous Staffetta Data Transmission

0 5

10 15 20 25 30

Duty

Cyc

le [%

]

DCmax

1 2 3 4 5Hops from Sink

Topolo

gy

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2

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S

How to create an activity gradient

1) Exploit relation between the activity of nodes and rendezvous time to create a gradient

0 5

10 15 20 25 30

Wa

keu

p F

req

. [H

z]

Without Staffetta With Staffetta

0

30

60

90

120

150

Fw

d.

de

lay

[ms]

Rendezvous w/o Staffetta Rendezvous Staffetta Data Transmission

0 5

10 15 20 25 30

Du

ty C

ycle

[%

]

DCmax

1 2 3 4 5Hops from Sink

To

po

log

y

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S


How to exploit an activity gradient

2) Use Activity Gradient to improve the efficiency of opportunistic data collection protocolsShorter forwarding delays

Biased opportunistic choices (more likely to reach good nodes)

Exploit temporal links

Handle high traffic loads around the sink

Increased adaptability to network dynamics


EVALUATIONStaffetta’s


Protocols comparison

DUTY CYCLE MAC Routing metricORW

FIXEDGENERIC

LPL + ANYCAST

Expected Duty Cycle (ORW)

Queue Backlog (BCP)

STAFFETTA None - Random Walk

We evaluated Staffetta against 1 opportunistic protocol and 3 routing metrics on 2 testbeds


Comparison with ORW

ORW ST.EDC ORW ST.EDC ORW ST.EDC

0

50

100

150

200

250

300Rate 1/30 Hz Rate 1/60 Hz Rate 1/240 HzPerformance improvements

Latency 80-450xDuty Cycle 2-9xDelivery Ratio up to 1.5x

ORW ST.EDC ORW ST.EDC ORW ST.EDC0.8

0.85

0.9

0.95

1.0Rate 1/30 Hz Rate 1/60 Hz Rate 1/240 Hz

ORW ST.EDC ORW ST.EDC ORW ST.EDC0

1

2

3

4

5

6Rate 1/30 Hz Rate 1/60 Hz Rate 1/240 Hz

late

ncy

[s]

deliv

ery

ratio

duty

cyc

le [

%]


Latency improvements

EDC ST.EDC QB ST.QB RW ST.RW0

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20

30


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100

150

200

Staffetta achieves low latencies by reducing the forwarding time and the path length

path

leng

th [h

op]

late

ncy

[s]


Delivery Ratio improvements


50

100

150

200


0.2

0.4

0.6

0.8

1

Staffetta improves the delivery ratio by reducing queue backlog (but ...)

late

ncy

[s]

deliv

ery

ratio


Duty Cycle improvements


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20

Staffetta reduces the energy consumption even if it increases the nodes’ activity

wak

eup

freq.

[Hz]

duty

cyc

le [

%]


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4

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10

12


Adaptability

1

2

3

Nodes close to 1Nodes close to 2Nodes close to 3


Adaptability

0 100 200 300 400 500 6000

4

8

12W

ake

up F

req. [H

z] Nodes close to position 1

0 100 200 300 400 500 6000

4

8

12

Wake

up F

req. [H


0 100 200 300 400 500 600

Time [s]

0

4

8

12

Wake

up F

req. [H


sink moves


0 100 200 300 400 500 6000

4

8

12W

ake

up F

req. [H


0 100 200 300 400 500 6000

4

8

12

Wake

up F

req. [H


0 100 200 300 400 500 600

Time [s]

0

4

8

12

Wake

up F

req. [H


Adaptability sink moves


Adaptability140 160 180 200 220 240 2600

100

200

300

La

ten

cy [

s] Nodes close to pos. 1 Nodes close to pos. 2 Nodes close to pos. 3

140 160 180 200 220 240 260Time [s]

0

0.5

1

1.5

2

Th

rou

gh

pu

t [m

sg/s

]

140 160 180 200 220 240 260 0

1

2

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Late

ncy

[s] Nodes close to pos. 1 Nodes close to pos. 2 Nodes close to pos. 3

140 160 180 200 220 240 260Time [s]

0

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Th

rou

gh

pu

t [m

sg/s

]

FIXED

STAFFETTA


CONCLUSIONS


Conclusion

Staffetta’s simple rule is able to

• Achieve desired network lifetime• Adapt to network changes

and generate an activity gradient that

• Biases opportunistic choices towards the sink• Reduces latency, path length and energy consumption

github.com/cattanimarco/Staffetta-Sensys-2016


THANKS A LOT

Staffetta: Smart Duty-Cycling for Opportunistic Data Collection

Presentations & Public Speaking

Transcript of Staffetta: Smart Duty-Cycling for Opportunistic Data Collection