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MACA-BI(MACA By Invitation)A Receiver Oriented Access Protocol for Wireless Multihop Network

F. Talucci, M. Gerla, and L. FrattaProceedings of IEEE PIMRC'97

(Personal, Indoor and Mobile Radio Communications-1997)

Speaker: Earl Kuo

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Outline

Introduction Related WorkMACA illustratedMACA-BI illustratedCollisions in MACA-BISimulationConclusion

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Introduction

Tx-Rx turn-around time (the transition time from transmit to receive state)

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Related Work[8]L.Kleinrock and F.Tobagi. “Packet switching in radio channels : Part 1 carrier sense multiple-access modes and their throughput-delay characteristic.” IEEE Trans Comm COM-23 no 12:1400-1416,1975.[7]P. Karn. “MACA a new channel access method for packet radio” In 9th Computer Networking Conference, pages 134-140. ARRL/CRRL Amateur Radio,1990.solves hidden terminal problem[4]C.L. Fullmer and J. Garcia-Luna-Aceves. “Floor acquisition multiple access (FAMA) for packet-radio networks.” In SIGCOMM’9, pages 262-273. ACM,August 1995.Cambridge, MA(USA).extend MACA by adding carrier sensing

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MACA and MACA-BI illustrated

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MACA and MACA-BI illustrated

Sender Receiver

RTS

CTSData

Sender Receiver

RTR

Data

MACA protocol - three way handshake

MACA-BI protocol - two way handshake

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MACA-BI illustrated

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MACA-BI illustrated (cont.)MACA-BI: The suppression of CTS packet is the main

idea Is two way handshake protocol RTR (Ready to Receive)

Indicating the readiness to receive a certain number of packets

assume that each data packet carries the information about the backlog in the transmitter (sender)

From the backlog notification and from previous history (receiver)

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MACA-BI illustrated (cont.)

Sender Receiver

RTR

Data

MACA-BI protocol - two way handshake

Reply with the requested and with the new backlog information

Predict which neighbors have (how many) packets to send

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MACA-BI Specifications

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MACA-BI Specifications (cont.)

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MACA-BI Specifications (cont.)

Status = remoteCall receive

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RTR

RTR

data

data

RTR

Wait(MAX(Pd+2*Tp,Timer)

RTR

Wait(Pd+2*Tp)

s

d

o

o

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MACA-BI Specifications (cont.)

RTR to otherswait

senderData

RTR

RTR

receiver

RTR to me

overhear node

Data

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Collisions in MACA-BIData collision

The channel is assumed to be noise free and symmetric

Node A transmits a data packet to B and simultaneously, node C transmits a data packet to B or to D

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Collisions in MACA-BIC transmits a data packet to B. This is impossible since node B can invite only one node at a timeC transmits a data packet to D. This can happen only if C did not hear the RTR from B to A

B transmitted RTR to A while C was transmittingThis is impossible since transmission from C would have been heard from B, preventing its RTR transmission to A

B transmitted RTR to A while C was receiving an RTR from D This is impossible because the RTR from D would have conflicted (at node C) with RTR from B thus preventing the subsequent data transmission from C to D

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Simulation single-hop caseData packet length=296 bytesControl packet length=20 bytesPropagation delay=54µs (radius =10 miles)Channel speed=10Mbps

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Simulation multi-hop case (throughput)

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Simulation multi-hop case (throughput)

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Simulation multi-hop case (delay)

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Simulation multi-hop case (delay)

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Conclusion

A new multiple access protocol for wireless networks called MACA-BI has been presentedTurn-around time overheadMACA functionality is preserved in MACA-BIMACA-BI is data collision free in the same sense as MACAMACA-BI is less vulnerable to control packet corruption than MACA

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Discussion

About algorithm

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Thank you!!

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Status = remote Call receive

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MACA protocol

The MACA protocol. (a) A sending an RTS to B.(b) B responding with a CTS to A.

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Source

Destination

Node in

Transmission Range

RTS

NAV(RTS)

NAV(CTS)

CTSP T

DATAP T

P T: Propagation timePropagation time

MACA protocol

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MACA-BI state diagramPassive

Send RTRRemote

RTR to metransmit(data)

Wait (random (Ts))

Send RTRwait(2*Tp)

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Passive

Send RTRRemote

Wait (random (Ts))

Send RTRwait(2*Tp)RTR to otherwait(Td+2*Tp)

wait(Td+2*Tp)

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Passive

Send RTRRemote

Wait (random (Ts))

Send RTRwait(2*Tp)RTR to otherwait(Td+2*Tp)

DataPCK to upper layers

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Passive

Send RTRRemote

Wait (random (Ts))

Send RTRwait(2*Tp)

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Passive

Send RTRRemote

Wait (random (Ts))

Send RTRwait(2*Tp)RTR to otherwait(Td+2*Tp)

wait(Td+2*Tp)

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Passive

Send RTRRemote

Wait (random (Ts))

Send RTRwait(2*Tp)RTR to otherwait(Td+2*Tp)

wait(Td+2*Tp)

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Passive

Send RTRRemote

Wait (random (Ts))

Send RTRwait(2*Tp)RTR to otherwait(Td+2*Tp)

wait(Td+2*Tp)

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Passive

Send RTRRemote

Wait (random (Ts))

Send RTRwait(2*Tp)RTR to otherwait(Td+2*Tp)

wait(Td+2*Tp)

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Passive

Send RTRRemote

1. RTR to metransmit data2. DataPCK to upper layers3. Error

RTR to otherwait(Td+2*Tp)

1. Wait (random (Ts))2. RTR to others wait(Max

(Timer,Td+2*Tp))3. DataPCK to upper layers

wait(Timer)4. Defaultwait(Timer)

Send RTRwait(2*Tp)

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Passive

Send RTRRemote

1. RTR to metransmit data2. DataPCK to upper layers3. Error

RTR to otherwait(Td+2*Tp)

1. Wait (random (Ts))2. RTR to others wait(Max

(Timer,Td+2*Tp))3. DataPCK to upper layers

wait(Timer)4. Defaultwait(Timer)

Send RTRwait(2*Tp)

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