Transcript Routing Protocols for Sensor Networks

Routing Protocols for Sensor
Networks
An Application Specific Protocol Architecture for Wireless
Microsensor Networks
by
Anantha Chandrakasan, Wendi Rabiner Heinzelman, and Hari
Balakrishnan
Presented by
Siva Desaraju
Computer Science
WMU
LEACH
Outline
Introduction
 Background
 Architecture
 Operation
 Analysis and Simulation
 Results
 Comparisions
 Conclusion

Introduction

Sensor Network Challenges
– Limited communication bandwidth
– Limited energy
Parameters
(Design goals)
– Ease of deployment
– System lifetime
– Latency
– Quality
– Neighboring nodes may have same data
– End user cares about a higher-level description of events
LEACH (Low-Energy Adaptive
Clustering Hierarchy)

Techniques (to achieve the design goals)
–
–
–
–
Randomized, adaptive, self-configuring cluster formation.
Localized control of data transfers
Low energy media access control (MAC)
Application specific data processing, such as data aggregation
and compression.
Background
Some application specific protocols developed for MSN
Minimum
Transmission Energy (MTE)
– For 3 nodes A, B and C, A would transmit to node C through B
iff (ETX – total transmit energy)
ETX(d=dAB) + ETX(d=dBC) < ETX(d=dAC)
– Only consider transmitter energy, neglects energy dissipation
of the receivers
Clustering
– Nodes send data to central cluster head
– Cluster head forwards data
– Cluster head has to be high energy node
– Fixed Infrastructure
LEACH Protocol Architecture

Assumptions
– All nodes can transmit with enough power to reach the base
station if needed
– Each node has computational power to support different
MAC protocols
– Nodes always have data to send
– Nodes located to each other have correlated data
LEACH in brief

All non-cluster head nodes transmit data to their cluster head

Cluster head receives this data and performs signal processing
functions on the data and transmits data to the remote BS

Nodes organize themselves into local clusters, with one node as
cluster head
Operation

Divided into rounds
– Set-up phase
–
Clusters are organized
– Steady phase
–
Data transferred from nodes to cluster and on to BS
LEACH Step by Step

Cluster Head Selection
– Each sensor elects itself to be cluster head at the beginning
of a round
– Nodes that have not already been cluster heads recently,
may become cluster heads
– Probability of becoming a cluster head is set as a function of
nodes’ energy level relative to the aggregate energy
remaining in the network
–
Average energy of nodes in each cluster X Number of
nodes in the network
LEACH Step by Step contd…

Cluster Formation
– Each cluster head node broadcasts an advertisement message
(ADV) using CSMA MAC Protocol
–
The message consists of the nodes’ ID and a header that distinguishes it
as an ADV message
– Each non-cluster head node determines its cluster/cluster head that
requires minimum communication energy
–
Largest signal strength, minimum transmit energy for communication
– Each node transmits a join-request message (REQ) using CSMA
MAC Protocol
–
The message consists of node’s ID and cluster head ID
– Each cluster head node sets up a TDMA schedule and transmits it
–
This ensures that there is no collision in data messages, radio
components can be turned off at all times except during transmit time
Setup phase complete
Flowchart
LEACH step by step contd…

Steady State Phase
– Nodes send data during their allocated time slot
– Once the cluster head receives all data it performs data
aggregation
– Resultant data is sent from cluster head to BS (a high
energy transmission)
– Uses transmitter based code assignment to reduce intercluster interference
– Cluster head senses the channel before transmission
Steady phase complete
LEACH-C:BS Cluster Formation

Uses a central control algorithm to form clusters
– During setup phase each node sends its location and
energy level to BS
– BS assigns cluster heads and clusters
– BS broadcasts this information
Analysis and Simulation

Using ns

Experiment setup
– 100-node network
– Nodes randomly distributed between (0,0) and (100,100)
– BS at location (50,175)
– Bandwidth of the channel 1Mbps
– Each data message 500 bytes long
– Packet header 25 bytes
– Simple radio model
Results:Limited energy Simulations


LEACH distributes more data per unit energy than MTE
LEACH-C delivers 40% more data per unit energy than LEACH
Results contd…


LEACH can deliver 10 times the amount of effective data to BS
as MTE for the same number of node deaths
Benefits of rotating cluster heads is seen
Conclusions

Advantages
– Outperforms conventional routing protocols
– LEACH is completely distributed, requiring no control
information from the base station
– Nodes do not need global topology information

Disadvantages
– Nodes must have data to send in the allotted time
– Perfect correlation is assumed, which might not be true always
Comparisions
SPIN
LEACH
Directed
Diffusion
Optimal
Route
No
No
Yes
Network
Lifetime
Good
Very Good
Good
Resource
Awareness
Yes
Yes
Yes
Use of
Meta-data
descriptors
Yes
No
Yes
References
 An Application Specific Protocol Architecture for
Wireless Microsensor Networks by Anantha
Chandrakasan, Wendi Rabiner Heinzelman, and
Hari Balakrishnan
 Energy-efficient Communication Protocol for
Wireless Sensor Networks by Anantha
Chandrakasan, Wendi Rabiner Heinzelman, and
Hari Balakrishnan (IEEE Transactions on wireless
communications, vol. 1, no. 4, Oct 2002)
Questions/Comments?
Thanks