8/11/2019 A Rate-Adaptive MAC Protocol for Multi-Hop

1/15

A Rate-Adaptive MAC Protocol for Multi-HopWireless Networks

Gavin Holland Nitin VaidyaDept. of Computer Science

Texas A&M UniversityCollege Station, TX 77843-3112

Paramvir BahlMicrosoft ResearchOne Microsoft Way

Redmond, WA 98052-6399

ABSTRACT

1. INTRODUCTION

To appear in

, Rome, Italy, July 2001.

0 10 20 30 40

SNR (dB)

1E-07

1E-06

1E-05

1E-04

1E-03

1E-02

1E-01

BER

QAM256 (8Mbps)

QAM64 (6Mbps)

QAM16 (4Mbps)

QPSK (2Mbps)

BPSK (1Mbps)

8/11/2019 A Rate-Adaptive MAC Protocol for Multi-Hop

2/15

50 100 150 200 250 300

Distance (m)

0

1000

2000

3000

4000

Mea

nThroughput(Kbps)

QAM256 (8Mbps)

QAM64 (6Mbps)

QAM16 (4Mbps)

QPSK (2Mbps)

BPSK (1Mbps)

1.1 Rate Adaptation

8/11/2019 A Rate-Adaptive MAC Protocol for Multi-Hop

3/15

30.0 30.1 30.2 30.3 30.4 30.5

Time (s)

05

1015202530

SNR(dB)

BPSK (1 Mbps)

QPSK (2 Mbps)

QAM16 (4 Mbps)

QAM64 (6 Mbps)

QAM256 (8 Mbps)

30.0 30.1 30.2 30.3 30.4 30.5

Time (s)

0

2

4

6

8

Rate(Mbps)

1.2 Motivation

8/11/2019 A Rate-Adaptive MAC Protocol for Multi-Hop

4/15

1.3 Paper Organization

2. OVERVIEW OF IEEE 802.11

2.1 Distributed Coordination Function (DCF)

DATAD

CTSD

1T

0T

2T

4T

3T

DRTS

CTS

Src

Dst

RTS

ACK

A

B

L

Time

DATA

2.2 Network Allocation Vector (NAV)

8/11/2019 A Rate-Adaptive MAC Protocol for Multi-Hop

5/15

8/11/2019 A Rate-Adaptive MAC Protocol for Multi-Hop

6/15

Frame

Control

Duration

Address

Dest

Control

Sequence

Address

Source

0

0

1

1

0

0

1

1

0

0

1

1

01

2Octets: 2

MAC Header

6 6 2 0 - 2312 4

BodyBSSID FCS

6

Frame

Control

Frame

Control Address

Dest

Address

Source

Address

Dest

0

0

1

1

2

Duration

2Octets:

Duration

4

FCS

66 6

FCS

4

CTS Frame

Octets:2 2

RTS Frame

4. INCORPORATION OFRBARINTO802.11

Frame

Control Address

Source

Address

Dest BSSID

Control

Sequence FCSBody

0

0

1

1

0

0

1

1

0

0

1

1

0

0

1

1

01

2Octets:

Reservation Subheader

Duration

6 6 6 2 0 - 2308 44

HCS

MAC Header

2

Frame

Control

Frame

Control Address

Dest

Address

Source

Address

Dest

LengthRate

0

0

1

1

Bits: 4 12

LengthRate

Bits: 4 12

00110 00 0

0 0

1 11 1

1 1

0 0 00 0 0

0 0 0

1 1 11 1 1

1 1 1

0 00 0

0 0

1 11 1

1 1

0 0 00 0 0

0 0 0

1 1 11 1 1

1 1 1

22Octets: 4

FCS

66 6

FCS

4

RTS Frame CTS Frame

Rate &

Length

Rate &

Octets:2 2

Length

0 0

0 0

0 0

1 1

1 1

1 1

0 0 0

0 0 0

0 0 0

1 1 1

1 1 1

1 1 1

Octets: 2 1 2

Sync SFD Signal Service Length CRC

16 1 2

Bits: 4

Data

Rate

RSH

Rate

4

8/11/2019 A Rate-Adaptive MAC Protocol for Multi-Hop

7/15

5. SIMULATION ENVIRONMENT

5.1 Autorate Fallback Algorithm (ARF)

0 100 200 300

ARF Timeout (ms)

0

500

1000

1500

2000

MeanThroughput(Kbps)

fixed

2 m/s

10 m/s

8/11/2019 A Rate-Adaptive MAC Protocol for Multi-Hop

8/15

5.2 Receiver-BasedAutoRate Protocol(RBAR)

5.3 Error Model

8/11/2019 A Rate-Adaptive MAC Protocol for Multi-Hop

9/15

5.4 Network Configurations

Configuration 1

Configuration 2

6. PERFORMANCE EVALUATION

6.1 Overhead of the Reservation Subheader

8/11/2019 A Rate-Adaptive MAC Protocol for Multi-Hop

10/15

0 500 1000 1500

Packet Size (bytes)

-0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

MeanThroughputofRB

AR(RelativetoARF)

431 2

Flow2Flow1

RSH

Scenario 2

1 2 43

Flow1 Flow2

RSH

Scenario 1

6.2 Slow Changing Channel Conditions

8/11/2019 A Rate-Adaptive MAC Protocol for Multi-Hop

11/15

50 100 150 200 250 300

Distance (m)

0

1000

2000

3000

4000

Mea

nThroughput(Kbps)

ARF

QAM256 (8Mbps)

QAM64 (6Mbps)

QAM16 (4Mbps)

QPSK (2Mbps)

BPSK (1Mbps)

50 100 150 200 250 300

Distance (m)

0

1000

2000

3000

4000

MeanThroughput(Kbps)

RBAR

QAM256 (8Mbps)

QAM64 (6Mbps)

QAM16 (4Mbps)

QPSK (2Mbps)

BPSK (1Mbps)

50 100 150 200 250 300

Distance (m)

0

1000

2000

3000

4000

Mea

nThroughput(Kbps)

RBAR-P

QAM256 (8Mbps)

QAM64 (6Mbps)

QAM16 (4Mbps)

QPSK (2Mbps)

BPSK (1Mbps)

6.3 Fast Changing Channel Conditions

8/11/2019 A Rate-Adaptive MAC Protocol for Multi-Hop

12/15

0 5 10

Mean Node Speed (m/s)

0

500

1000

MeanThroughput(Kbps)

RBAR

ARF

QAM256 (8Mbps)

QAM64 (6Mbps)

QAM16 (4Mbps)

QPSK (2Mbps)

BPSK (1Mbps)

0 5 10

Mean Node Speed (m/s)

0

200

400

600

800

MeanThroughput(Kbps)

RBAR

ARF

QAM256 (8Mbps)

QAM64 (6Mbps)

QAM16 (4Mbps)

QPSK (2Mbps)

BPSK (1Mbps)

6.4 Impact of Variable Traffic Sources

0 10 20 30

Mean Burst Length (ms)

0.0

0.2

0.4

0.6

0.8

1.0

DeliveryRatio(PktsRx/PktsT

x)

RBAR

ARF

6.5 Multi-Hop Performance

8/11/2019 A Rate-Adaptive MAC Protocol for Multi-Hop

13/15

30.0 30.1 30.2 30.3 30.4 30.5

Time (s)

05

1015202530

SNR(dB)

BPSK (1 Mbps)

QPSK (2 Mbps)

QAM16 (4 Mbps)

QAM64 (6 Mbps)

QAM256 (8 Mbps)

30.0 30.1 30.2 30.3 30.4 30.5

Time (s)

0

2

4

6

8

Rate(Mbps)

0 10 20 30

Mean Burst Length (ms)

0.0

0.2

0.4

0.6

0.8

1.0

DeliveryRatio(PktsRx/PktsTx)

RBAR

ARF

0 5 10

Mean Node Speed (m/s)

0

100

200

300

400

MeanThroughput(Kbps)

RBAR

ARF

7. FUTURE WORK

8/11/2019 A Rate-Adaptive MAC Protocol for Multi-Hop

14/15

5 10 15 20 25 30

Scenario Number

0

500

1000

1500

2000

MeanTput(Kbps)

RBAR

ARF

5 10 15 20 25 30

Scenario Number

0

500

1000

1500

2000

MeanTput(Kbps)

RBAR

ARF

5 10 15 20 25 30

Scenario Number

0

500

1000

1500

2000

MeanTput(Kbps)

RBAR

ARF

5 10 15 20 25 30

Scenario Number

0

500

1000

1500

2000

MeanTput(Kbps)

RBAR

ARF

0 5 10

Mean Node Speed (m/s)

0

50

100

150

200

250

MeanThroughput(Kbps)

RBAR

ARF

8. CONCLUSION

9. ACKNOWLEDGMENTS

10. REFERENCES

8/11/2019 A Rate-Adaptive MAC Protocol for Multi-Hop

15/15