Tufts Wireless Laboratory
School Of Engineering
Tufts University
Paper Review
“An Energy Efficient Multipath Routing Protocol for
Wireless Sensor Networks”,
B. Yahya and J. Ben-Othman
Almir Davis
4/13/2015
1
Tufts Wireless Laboratory
School Of Engineering
Tufts University
Key Findings
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One of the best papers I have read so far in WSN arena
Very clear organization
A lot of information about already available architectures
Paper proposes a unique, innovative approach to solve
power problem in WSN (called EMR1 and EMR2)
• A lot of testing and performance benchmarking included
to back the theory
4/13/2015
2
Tufts Wireless Laboratory
School Of Engineering
Tufts University
Why traditional routing cannot
be implemented in WSNs? (1)
• routing protocols cannot be applied to sensor networks,
where building a global addressing scheme is necessary for
such protocols to work, which is not feasible in large scale
deployments of sensor networks
• in many applications of sensor networks, the flow of the
sensed data should be from different sources to a single
target (sink node)
• sensor nodes are tightly constrained in terms of battery
power, processing power, and storage capacity, and
hence a careful resources management is required.
4/13/2015
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Tufts Wireless Laboratory
School Of Engineering
Tufts University
Routing Techniques Classification
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negotiation based
query based
QoS based
multipath based (this paper is based on
this technique)
4/13/2015
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Tufts Wireless Laboratory
School Of Engineering
Tufts University
EMR (Efficient Multipath Routing)
• EMR uses the residual energy, node
available buffer size, and Signal-to-Noise Ratio
(SNR) to predict the next hop through the path
construction phase
• Two EMR Protocols:
– EMR-1
– EMR-2
4/13/2015
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Tufts Wireless Laboratory
School Of Engineering
Tufts University
EMR-1
• EMR-1: uses a single path among the
discovered paths to transfer the whole data
message, when this path cost falls bellow a
certain threshold, it then switches to the next
alternative path.
4/13/2015
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Tufts Wireless Laboratory
School Of Engineering
Tufts University
EMR-2
• EMR-2: adds data redundancy to the
original data message and uses multiple
paths to transmit the data
4/13/2015
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Tufts Wireless Laboratory
School Of Engineering
Tufts University
Related Work (1)
• Sequential Assignment Routing (SAR) protocol - SAR protocol is
a multi-path routing protocol that makes routing decisions based
on three factors: energy resources, Quality of Service (QoS) on
each path, and packet’s priority level (increases fault tolerance
but suffers from overhead of maintaining tables)
• Chang and L. Tassiulas have proposed a multipath routing
protocol (nodes in the first path will not completely drain their
energy through continual use of the same path, hence achieving
longer lifetime. Here, the path switching cost is an incremental
overhead. )
4/13/2015
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Tufts Wireless Laboratory
School Of Engineering
Tufts University
Related Work (2)
• Directed Diffusion Paradigm: the source node or an intermediate
node selects one path from the available multiple paths to
delivery the data to sink, based on the quality of data delivery (e.g.
delay, throughput). Based on the changes on the network
conditions, a node may change its primary path to another one
(limited by the inherent delay of such scheme to switch to and
establish a new primary path in case of network error conditions. As
well, in case of path failure, the protocol lacks of an efficient
retransmission control mechanism which depletes quickly the
node energy resources)
4/13/2015
9
Tufts Wireless Laboratory
School Of Engineering
Tufts University
Description of EMR Protocol (1)
• Assumptions:
– sensor nodes are distributed randomly in the sensing field
– All nodes have the same transmission range
– enough battery power to carry their sensing, computing, and
communication activities
– Network is fully connected and dense
– Additionally, at any time, we assume that each
– sensor node is able to compute its residual energy, and its
available buffer size, as well as record the link performance
between itself and its neighboring node in terms of signal-to-noise
ratio (SNR).
4/13/2015
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Tufts Wireless Laboratory
School Of Engineering
Tufts University
Description of EMR Protocol (2)
• Link Cost Function:
– Cost function includes an energy factor, available buffer factor, and
interference factor with appropriate weights (α, β, and γ):
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Tufts Wireless Laboratory
School Of Engineering
Tufts University
Description of EMR Protocol (3)
• Discovery Procedure:
– Initialization phase
– Primary Path discovery phase
– Alternative Paths discover phase
• Path Maintenance
• Traffic allocation and data transmission
– Transfer through Single-path at a time
– Transfer data across multiple paths simultaneously
4/13/2015
• Paths Selection
• Message Segmentation
• Message Forwarding and Recovery
12
Tufts Wireless Laboratory
School Of Engineering
Tufts University
EMR Performance Evaluation
• Assumptions:
– NS-2 Simulation environment
– Comparison made against N-to-1 multipath routing
protocol and Directed Diffusion
– Field 500mx500m
– Node radio transmission range set to 25m
– Performance matrix: Average Energy Consumption,
Delivery Ration, and Delay
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Tufts Wireless Laboratory
School Of Engineering
Tufts University
EMR Performance Evaluation
• Average Energy Consumption:
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Tufts Wireless Laboratory
School Of Engineering
Tufts University
EMR Performance Evaluation
• Delivery Ratio:
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Tufts Wireless Laboratory
School Of Engineering
Tufts University
EMR Performance Evaluation
• Delay:
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Tufts Wireless Laboratory
School Of Engineering
Tufts University
EMR Performance Evaluation
• Average Energy Consumption:
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Tufts Wireless Laboratory
School Of Engineering
Tufts University
EMR Performance Evaluation
• Delivery Ratio:
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Tufts Wireless Laboratory
School Of Engineering
Tufts University
EMR Performance Evaluation
• Delay:
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