Paper Review

1
Paper ReviewAn Energy Efficient Multipath
Routing Protocol for Wireless Sensor Networks,
B. Yahya and J. Ben-Othman

• Almir Davis

2
Key Findings

• 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

3
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
Routing Techniques Classification

• negotiation based
• query based
• QoS based
• multipath based (this paper is based on this
  technique)

5
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

6
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.

7
EMR-2

• EMR-2 adds data redundancy to the
  original data message and uses multiple
  paths to transmit the data

8
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 packets
  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. )

9
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)

10
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).

11
Description of EMR Protocol (2)

• Link Cost Function
• Cost function includes an energy factor,
  available buffer factor, and interference
  factor with appropriate weights (a, ß, and ?)

12
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
• Paths Selection
• Message Segmentation
• Message Forwarding and Recovery

13
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

14
EMR Performance Evaluation

• Average Energy Consumption

15
EMR Performance Evaluation

• Delivery Ratio

16
EMR Performance Evaluation

• Delay

17
EMR Performance Evaluation

• Average Energy Consumption

18
EMR Performance Evaluation

• Delivery Ratio

19
EMR Performance Evaluation

• Delay