Enhancement of Receiver-initiated Packet Train Protocol with Slotted Random Access for Underwater Acoustic Networks

Nuttarit Leelapisut1, Nitthita Chirdchoo2, Muhammad Saadi1, Lunchakorn Wuttisittikulkij1

1. Department of Electrical Engineering, Faculty of Engineering, Chulalongkorn University

2. Sensor Network and Embedded System Research Unit, Nakhon Pathom Rajabhat University

Outline

IntroductionProtocol DesignSimulation & ResultsSummary

2

Introduction

•Why Underwater?▫The ocean covers 71% of the Earth's

surface and contains 97% of the planet's water.

▫more than 95% of the underwater world remains unexplored.

•Example of Application in underwater▫Pollution monitoring▫Offshore exploration▫Oceanographic data collection

3

Underwater Communication Characteristics• Most underwater sensor networks are based on

acoustic waves.▫Propagation speed 1500m/s

Lead to long propagation delay 0.67s/km▫Scarce bandwidth availability

Lead to low datarate a few kbps▫Terrestrial MAC protocols cannot be applied

directly to Underwater Acoustic Networks.• Example for MAC for Underwater Acoustic

Network▫MACA-U, RIPT, SF-MAC, CS-MAC, Aloha-AN

4

5

RIPT

•RIPT was proposed by Chirdchoo et al.(2008)▫is handshaking with Receiver-initiated

protocol.▫with packet train that can send more than

one DATA packet in each handshake round.

6

RIPT

• Strong▫More effective in term of alleviating the hidden

terminal problems.• Weakness

▫Each node must know the inter-node’s propagation delay of all other nodes.

▫RIPT protocol adapt the frame size of data transmission period according to the number of data packets from the previous handshaking round. May be not match with current traffic demand Cause low Throughput

7

E-RIPT

•E-RIPT is from Enhance RIPT•Main point of E-RIPT protocol

▫Use the slotted random access at reservation time. Reduce the requirement of original RIPT

that need to know all inter-node propagation delay

▫Set frame size after received traffic demand from neighboring node. Increase channel utilization

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Node Type

•Beacon node▫Process and Control the Slave

node(s).▫Receive DATA packet(s) from Slave

node(s).•Slave node

▫Reserve the data slot which declare from beacon

▫Send DATA packet to Beacon node• Idle node

▫Node which wait for changing type

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E-RIPT Protocol

Node 4

SlaveNode 2

SlaveNode 1

BeaconNode 3

SlaveNode 5

SlaveNode 6

Silent

tou

t1

tou

t1

tou

t1

tou

t1

tou

t1

REVNTF1REV-ACK

ORDERBROADCAST

NTF2

Beacon

Slave

Slave

Slave Slave

Silent

DATA

REV• Beacon node ID• No reservation Slot

NTF1• Time till tout1

REV-ACK• Number of packet wish to

send• Time till tout1

ORDER• Time and Number of DATA

packet(s) for Slave to send.

Sall = 4

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E-RIPT Protocol

Node 4

SlaveNode 2

SlaveNode 1

BeaconNode 3

SlaveNode 5

Slave

Node 6

Silenttou

t1

tou

t2

tou

t2

tou

t2

tou

t,b

tou

t2

tou

t2

REVNTF1REV-ACK

ORDERBROADCAST

NTF2

Beacon

Slave

Slave

Slave Slave

Silent

DATA

NTF2• Time till tout2

Sall = 4

Simulation Model• We used open source simulator NS-3,

with UAN module.• Simulation model is the same as RIPT

simulation model.▫ 36 nodes each node has

8 1-hop neighboring nodes 16 2-hop neighboring nodes

▫ Wraparound▫ Deviate from intersection point a

maximum 10% in x and y direction

• Datarate = 2400 bps• DATA packet length = 2400 bit• Grid Spacing = 700m• We choose to benchmark our

protocol with RIPT and MACA-U

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12

Result-Throughput

0 0.01 0.02 0.03 0.04 0.05 0.06 0.070

0.005

0.01

0.015

0.02

RIPTMACA-UE-RIPT S

all = 2

E-RIPT Sall

= 4

E-RIPT Sall

= 8

E-RIPT Sall

= 10

E-RIPT Sall

= 12

E-RIPT Sall

= 14

E-RIPT Sall

= 16Nor

mal

ized

thro

ughp

ut p

er n

ode

Normalized offered load per node

Sall = No. 1-hop neighboring node

Result-Delay

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0 0.01 0.02 0.03 0.04 0.05 0.06 0.070

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

RIPTMACA-UE-RIPT with S

all = 2

E-RIPT with Sall

= 4

E-RIPT with Sall

= 8

E-RIPT with Sall

= 10

E-RIPT with Sall

= 12

E-RIPT with Sall

= 14

E-RIPT with Sall

= 16

End

-to-

End

pac

ket d

elay

(se

cond

s)

Normalized offered load per nodeSall = No. 1-hop neighboring node

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Result-Fairness

• Number of packets sent with offerload per node = 0.503▫ RIPT,

Mean = 38528.1389, SD = 4922.9368

▫ E-RIPT Sall = 8, Mean = 41608.8056, SD = 3470.5466

▫ MACA-U,Mean = 18598.6944, SD = 906.4938

0 10 20 300

1

2

3

4

5x 10

4

0 10 20 300

0.5

1

1.5

2

2.5x 10

4 MACA-U0 10 20 30

0

1

2

3

4

5x 10

4 RIPT

E-RIPT Sall =

8

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Summary

• E-RIPT▫ can reduce the requirement of original

RIPT by using slotted random access.▫ can decrease the time latency, improve

throughput and fairness of original RIPT protocol, if reservation slots are selected carefully.

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Q & A

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Thank you