An Opportunistic Directional MAC Protocol for
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An Opportunistic Directional MAC Protocol for Multihop Wireless Networks with Switched Beam Directional Antennas. 석사 1 학기 홍혁진 2009.4.27. Contents. Introduction Directional antennas Basic Directional MAC Protocol Opportunistic Directional MAC Protocol(OPDMAC) Conclusion. Introduction.

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1 2009 4 27

An Opportunistic Directional MAC Protocol forMultihop Wireless Networks with Switched BeamDirectional Antennas

석사1학기

홍혁진

2009.4.27


Contents

Contents

  • Introduction

  • Directional antennas

  • Basic Directional MAC Protocol

  • Opportunistic Directional MAC Protocol(OPDMAC)

  • Conclusion


Introduction

Introduction

  • Motivation

  • MAC protocol aims to fully exploit the benefits of spatial reuse introduced by the use of directional antennas.


Directional antennas

Directional antennas

  • Directional antennas

    Directional antennas in multihop wireless networks offer a potential increase in the spatial reuse of the wireless channel

  • Pros- spatial reuse,

    - reduce interference,

    - extend the transmission range

    - reduce power consumptions


Directional antennas1

Directional antennas

Silenced Node

C

B

A

D

A

  • Omni-directional Antennas


Directional antennas2

Directional antennas

Not possible using Omni

C

B

A

D

A

  • Directional Antennas


802 11 mac protocols with omi directional

A

B

C

D

E

RTS

RTS

CTS

CTS

DATA

DATA

ACK

ACK

802.11 MAC Protocols with omi-directional

This mechanism overcome hidden terminal problems but waste a large portion of the network capacity.

When B communicate with C, D defer the transmission to E until B, C completed.


D mac example

D-MAC Example

1. DRTS-DCTS-DDTAT-DACK

RTS(Request to Send)

CTS(Clear to Send)

DRTS

A

B

C

D

E

F


D mac example1

(c) 2002 Nitin Vaidya, UIUC

D-MAC Example

1. DRTS-DCTS-DDTAT-DACK

RTS(Request to Send)

CTS(Clear to Send)

DCTS

A

B

C

D

E

F


D mac example2

(c) 2002 Nitin Vaidya, UIUC

D-MAC Example

1. DRTS-DCTS-DDTAT-DACK

DDATA

A

B

C

D

E

F


D mac example3

D-MAC Example

1. DRTS-DCTS-DDTAT-DACK

DACK

A

B

C

D

E

F


D mac example4

D-MAC Example

2.ORTS-OCTS-DDTAT-DACK

RTS(Request to Send)

CTS(Clear to Send)

ORTS

A

B

C

D

E

F


D mac example5

D-MAC Example

2.ORTS-OCTS-DDTAT-DACK

RTS(Request to Send)

CTS(Clear to Send)

OCTS

A

B

C

D

E

F


D mac example6

D-MAC Example

2.ORTS-OCTS-DDTAT-DACK

DATA

A

B

C

D

E

F


D mac example7

D-MAC Example

2.ORTS-OCTS-DDTAT-DACK

ACK

A

B

C

D

E

F


Deafness

A

B

DATA

RTS

C

Deafness


Deafness1

A

B

DATA

B

CTS

ACK

CTS

RTS

Data

RTS

A

RTS

C

RTS

Backoff

RTS

Backoff

C

Deafness

  • C retransmits RTS and back off longer (it mis-deduces the congestion as the failure reason)

  • Underutilizes channel


D mac example8

D-MAC Example

3. DBTMA/DA(Dual busy Tone Multiple Access Protocol using direcitional Antenna)

DRTS

A

B

C

D

E

F


D mac example9

D-MAC Example

3. DBTMA/DA(Dual busy Tone Multiple Access Protocol using direcitional Antenna)

BTr(Receive busy tone)

BTt(Transmit busy tone)

DCTS

A

B

C

D

E

F

BTr

BTr


D mac example10

D-MAC Example

3. DBTMA/DA(Dual busy Tone Multiple Access Protocol using direcitional Antenna)

BTr(Receive busy tone)

BTt(Transmit busy tone)

DATA

A

B

C

D

E

F

BTt

BTt

BTt


D mac example11

D-MAC Example

3. DBTMA/DA(Dual busy Tone Multiple Access Protocol using direcitional Antenna)

ACK

A

B

C

D

E

F


D mac example12

D-MAC Example

4. RI-DMAC(Receviver-Initiated Directional Mac Protocol

DRTS

A

B

C

D

E

F

RTS1


D mac example13

D-MAC Example

4. RI-DMAC(Receviver-Initiated Directional Mac Protocol

DCTS

A

B

C

D

E

F

RTS2


D mac example14

D-MAC Example

4. RI-DMAC(Receviver-Initiated Directional Mac Protocol

DATA

A

B

C

D

E

F

RTS3


D mac example15

D-MAC Example

4. RI-DMAC(Receviver-Initiated Directional Mac Protocol

RTR(Ready to Receive)

ACK

A

B

C

D

E

F

RTR


Basic opdmac protocol

Basic OPDMAC Protocol

  • OPDMAC(Opportunistic Directional MAC Protocol )

    If a node is foced to backoff due to a missing CTS,

    OPDMAC explores transmission opportunity in other direction

  • Pros- minimizesthe idle wait time of the wireless channel

    - increase the channel utilization.

    - decrease the effect of deafness without additional control overhead


Operation of opdmac protocol

Operation Of OPDMAC Protocol

  • In case of a missing response

A

B

RTS

DATA

Z


Operation of opdmac protocol1

Operation Of OPDMAC Protocol

  • In case of a missing response

C

RTS

A

B

DATA

Z


Conclusion

Conclusion

  • OPDMAC is effective in alleviating the effect of both deafness and directional hidden terminal problems

  • OPDMAC also outperforms both IEEE 802.11 and Basic DMAC in terms of throughput, delay and fairness


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