Shekar Nethi, Jari Nieminen and Riku Jantti

Exploitation of Multi-Channel Exploitation of Multi-Channel Communications in Industrial Communications in Industrial Wireless Sensor Applications: Wireless Sensor Applications: Avoiding Interference and Enabling Avoiding Interference and Enabling CoexistenceCoexistence

Shekar Nethi, Jari Nieminen and Riku JanttiShekar Nethi, Jari Nieminen and Riku Jantti

WCNC 2011WCNC 2011

Speaker : Huei-Rung TsaiSpeaker : Huei-Rung Tsai

OutlineOutline

• Introduction

• Goals

• G-McMAC Protocol

• Simulation Results

• Conclusions

OutlineOutline

• Introduction

• Goals



• Conclusions

IntroductionIntroduction

• Industrial wireless sensor Employ Wireless Sensor and Actuator Networks (WSANs) Low-power sensors collect information about the physical world Sensors transmit the physical information to actuators wirelessly

• In industrial wireless sensor applications Channel conditions are very likely to vary and harsh IEEE 802.11 b/g networks may interfere IEEE 802.15.4 sensor networks

• Multi channel MAC protocol can improve the network performance


• Rendezvous problem is thorny in Multi-channel environment Sender and receiver rendezvous Data transmission channel

S R

Where is R?Where is R?

ch1ch3

ch3chN time

ch2

ch1

… …


• Existing multi-channel MACs can be divided into 4 classes Dedicated control channel Common hopping Parallel rendezvous Split phase


• Dedicated control channel Dynamic Channel Assignment (DCA) Two interfaces

• One is fixed on the control transmitted RTS/CTS/RES packets

• Other switches between data channel transmitted data/ACK packets

Shortcoming• More cost

Control channeltime

RTS CTS RES

Control Channel

R S

123 2 2Data channel?DATA ACK

NAV


• Common hopping based Channel-Hopping Multiple Access (CHMA)

• All the nodes obey a common hopping pattern and data transmission will take place on the current channel after a RTS/CTS handshake

Shortcoming• Energy consumption

Channel 3time

Channel 1

Channel 2

RTSRTS

CTSCTS

ORS

ORS

ORS

DATA(S,R)DATA(S,R)


• Parallel rendezvous SSCH: Slotted Seeded Channel Hopping for Capacity Improvement in

IEEE 802.11 Ad-Hoc Wireless Networks

Shortcoming• Energy consumption

f(A.mac)=1,2,0,0,3,1…

f(B.mac)=1,0,0,1,2,2…


• Split phase based Multi-channel MAC (MMAC)

Suitable for WSNs • Nodes can sleep after a contention period if they do not need to transmit or receive

ATIM Window Data Window

time

Beacon Interval


• The problem with these approaches is that predetermined frame structures

Makes the system inflexible

• WirelessHART is an industrial standard for wireless automation

Don’t specifically solve the problems • Related to real-time communications

• Co-existence of multiple overlapping networks

GoalsGoals

• Design a generic, flexible and robust multi-channel MAC protocol (G-McMAC)

Its enable coexistence of multiple wireless sensor applications It can dynamically adapt when network topology changed Achieves low transmission delays and high throughputs

OutlineOutline

• Introduction

• Goals



• Conclusions

• Network topology

G-McMAC ProtocolG-McMAC Protocol

GW1

1

3

4

2

6

5

GW2

GW3

8

8

8

• Channel arrangement


Beacon Period (BP)

Contention plus Data Period (CDP)

Beacon Interval

CCC

ch1

chN

ch2

time

... …

• Beacon Period (BP) Route establishment Exchange channel information Provide time synchronization

• Contention plus Data Period (CDP) Resource negotiations Data transmissions

• Common Control Channel (CCC)


CCC

ch1

chN

ch2

BP CDP


time

... …

GW 4 3 1 2

TDMA CSMA

Feedback assisted Beacon Collision Avoidance (FBCA)

: Beacon : RsACK: Sensing : RsREQ

2

2GW

DATA2→GW2

3 1

3 1DATA3→1


• Feedback assisted Beacon Collision Avoidance (FBCA) To avoid collisions To produce optimal sort

Hop0

Hop1

GW

4 3 1

BP CDP BP

GW

1 2 3 4

timeHop2

5 5 6

GW

BP CDP 1, 41, 4

1 4

6

2

… …

2

5 6

3

Expireslot

Expireslot


• Multiple Gatways network priority Primary networks Secondary networks

Hop0

Hop1

Hop2

GW1

4 3 1GW2

BP CDP BP

GW1

1 2 3GW2

6 5 5 6

GW2

BnAcREQ

GW2

7 8

Secondary BP

time

9


• Nodes sense the channel before starting a data transmission Miss resource reservations when transmission does not matter

• Nodes can reserve periodic transmissions simply by setting the Periodic Transmission bit as 1 in RsREQ message

OutlineOutline

• Introduction

• Goals



• Conclusions

Simulation ResultsSimulation Results

• The implementation of G-McMAC is done on ns2

• Environment Crane (overhead)Control System (CCS) — Primary network Machine Health Monitoring System (MHMS) Air Conditioning Unit (ACU)

• The goal is to achieve minimum performance degradation for high priority CCS with the added payload in the network


• G-McMAC effectively integrates application priority and achieves good performance in case of multiple overlapping WSANs


• These results show that G-McMAC is able to avoid interference and enables coexistence of multiple sensor applications

OutlineOutline

• Introduction

• Goals



• Conclusions

ConclusionsConclusions

• G-McMAC protocol achieves high throughput and low packet transmission delays while enabling coexistence of multiple overlapping wireless networks.

• In Simulation, showed a comprehensive set of simulation results from a real-world industrial application scenario to confirm that GMcMAC is suitable for industrial wireless sensor applications.

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Shekar Nethi, Jari Nieminen and Riku Jantti

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