Download of MARCH with MACA

<Sensor Network Seminar 2007 >
<출처 - IEEE 2000 >
MARCH : A Medium Access Control Protocol
For Multihop Wireless Ad Hoc Networks
2007. 5. 23
성백동
[email protected]
Agenda
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Abstract
Introduction
Related work
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The MARCH Procotol
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The Overhearing Mechanism
MARCH Illustration
Perframance Evaluation
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Sender-Initiated MAC Protocols
Receiver-Initiated MAC Protocols
End-to-End Throughput
End-to-End Delay
Conclusion
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Abstract
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MARCH
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utilizes the broadcast characteristics of an omnidirectional
antenna to reduce the number of control message
RTS-CTS handshake is used only by the first hop of a route
 collision is reduced and channel throughput is increased
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Introduction
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A multihop wireless ad hoc network consists of mobile
hosts(MHs) equipped with radio devices to cooperatively
form a communication network
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MHs
 may not be within transmission range of each other
 Can build a connection through other MHs
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Need to MAC protocol
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Use a common radio channel to communicate with one another
CSMA
 Simple
 hidden terminal problem
 Degrades performance
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Introduction
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Other protocols
 Developed various MAC protocol with an additional control handshake
before data transmission
 sender-initiated protocols
 receiver-initiated protocols
 less control overhead is required
 Outperform sender-initiated protocol
 but vulnerable
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MARCH(Multiple Access with ReduCed Handshake)
 combines the advantages of both sender- and receiver-initiated
protocols
 reduces the number of handshakes
 Outperform sernder-initiated protocol
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Related work

Sender-Initiated MAC Protocols
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MACA(Multiple Access Collision Avoidance)
 Use a request-response dialogue to solve the HTM problem
 Request-to-send(RTS) and Clear-to-send(CTS)
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MACAW
 Improvement of MACA
 Use more handshakes to handle problems associated with control
packet collision
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FAMA(Floor Acquisition Multiple Access)
 Improve MACA
 Adds carrier sensing capability in order to reduce the possibility of
collision
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Performance is quite limited when the traffic load is high
 high probability of control packet collision
 A lot of reTX and lowering the channel throughput
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Related work
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Receiver-Initiated MAC Protocols
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reduce the number of control packets
MACA-BI(MACA By Invitation)
 Based on the prediction
 predict the packet arrival time at its neighboring MHs
 send ready-to-receive (RTR) packets
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RIMA(Receiver Initiated Multiple Access)
 Improved MACA-BI
 Employs a new packet arrival prediction method
 Assumes that all MHs have the same packet arrival rate.
 When an MH receives a data packet, it assumes that its neighboring MH
also receives a data packet.
 It then sends an RTR packet to invite the neighboring MH to transmit.
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Reduce control overhead
 if the data packet arrival at a sender can be correctly predicted by its
receiver
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The MARCH Protocol
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reduced the amount of control overhead.
Operates without resorting to any traffic prediction
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Exploits the broadcast characteristic of omnidirectional antennas
to reduce the number of required handshakes
Approach
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An MH has knowledge of data packet arrival at its neighboring
MHs from the over heard CTS packet.
It can then initiate an invitation for the data to be relayed
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The MARCH Protocol
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The Overhearing Mechanism
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The overheard CTS1 packet can be used to convey the information
of a data packet arrival at MHB to MHC
Figure shows the new handshake process through the route
RTS-CTS handshake reduced to a single CTS(CTS-only)
handshake after the first hop
Reduction in the control overhead is a function of the route length
Ad hoc route of L hops
 The number of handshakes needed to send a data packet from the
source to destination
 2L in MACA , L in MACA-BI, and (L+1) in MARCH
 If L is large, MARCH will have very similar number of handshakes as in
MACA_BI
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The MARCH Protocol
The RTS-CTS handshake in MACA
The proposed handshake mechanism in MARCH protocol
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The MARCH Protocol
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MARCH Illustration
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Include information in an CTS/RTS packet
 The MAC address of the sender and the receiver
 The route identification number(RTID)
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Assume
 each MH keeps sensing the channel and will not transmit until the
channel is free
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The MARCH Protocol
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Two routes - can be established through an appropriate
routing protocol
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MHZ will overhear the CTS2 packet
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To avoid MHZ misinterpreting it and initiating an unnecessary CTSonly handshake
The MAC Layer has access to tables that maintain
information on the routes the node participates
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Route 1 consists of MHA , MHB , MHC, MHD
Route 2 includes MHY , MHC, and MHZ
Consult to understand if it should respond to a control msg to
certain route
MARCH does not participate in routing, nor makes any
decisions about the data packets exchanged
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in the network layer
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The MARCH Protocol
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Two overlapping routes in an ad hoc mobile network
Overhear CTS2
To avoid MHZ misinterpreting, the RTID method
Z
X
Include Timer TW
CTS1
CTS1
B
CTS2
CTS2
C
RTS1
A
Y
Route 1
Route 2
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D
Performance Evaluation
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Test environment
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Simulations using the OPNET tool
Compared the performance( throughput , overhead and delay)
of MARCH with MACA
Neighboring MHs are separated by 10 m
Each MH is within the tx range of its upstream and downstream
MH2
The channel is considered to be error free and its capacity is
1Mbps
Data size = 2048 bits
Control packet size = 128 bits
Generate data packets according to a Poissaon process with an
arrival rate varying from 10 pkt/sec to 350 pkt/sec
The TX-RX/RX-TX turn-around time of a radio transceiver is 25
usec and the length of a time slot is 1 usec
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Performance Evaluation
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Network topology
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Route 1
7
Route 2
2
3
4
10m
8
1
9
15
5
Performance Evaluation
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End-to-End Throughput
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Under high traffic load, MARCH achieves about 66% improvement
when compared to MACA
 The reduced handshake mechanism
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MH2 must content with MH1 and MH3 for the channel
 It is difficult for MH2 to forward data packet to MH3
 RTS packets transmitted by MH2 may collide at MH3, with other packets
coming from MH7 , MH4, or MH8
 In MARCH
 Transmissions between MH2 and MH3
 The CTS packets from MH3 may only collide with RTS packets from MH1
End-to-End Throughput Performance
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Performance Evaluation
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The control overhead associated with each protocol
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in MACA
 when the traffic load is greater than 50 pkt/sec, control packet
collisions result in a lot of reTX
 an increase in control overhead
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in MARCH
 has a lower probability of control packet collision
 Its control overhead is much less than MACA at all traffic loads
Route Control
17 Overhead
Performance Evaluation
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End-to-end Delay
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Under light traffic load, the delay in MARCH is higher than MACA
 The reduced handshake mechanism introduces an extra delay close
to the packet inter-arrival time at each intermediate MH
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As the traffic load increases beyond 50 pkt/sec
 the delay in MACA grows significantly when compared to MARCH
since control packet collisions cause a lot of queuing delay at MH2 and
MH7
 Packet queueing due to collisions does not happen in MARCH until
the traffic load is above 100 pkt/sec
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End-to-End Delay
Conclusion
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MARCH
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improves throughput, delay, and control overhead performance by
reducing the number of handshakes
Exploits the fact that control messages are overheard by
neighbors
 More deterministic and does not resort to network prediction
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The concepts can be applied to other multi-channel MAC protocols
to further improve their communication performance
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