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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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slide1

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, UIUCD-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, UIUCD-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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