protocols for self organisation of a wireless sensor network
DESCRIPTION
TRANSCRIPT
Presented by
Saatviga S.
PROTOCOLS FOR SELF-ORGANIZATION OF A
WIRELESS SENSOR NETWORKPublished in “Personal Communications, IEEE, vol 7, no
5, 2000”
Authors
Katayoun Sohrabi B.S & M.S degrees in Electrical Engineering, University of Missouri, Rolla.
Ph.D. University of California, Los Angeles
Vishal Ailawadhi B.S. and M.S. degrees in electrical engineering, Ph.D. in electrical
engineering, University of California, Los Angeles
Jay L. Gao B.S. and M.S. degrees in electrical engineering, Ph.D. in electrical
engineering, University of California, Los Angeles
Gregory J. Pottie B.Sc. in engineering physics, Queen’s University, Kingston, Ontario,
Canada. M.Eng. And Ph.D. in electrical engineering from McMaster
University, Hamilton, Ontario
Road Map
Wireless Sensor Network – A General Scenario
Design Challenges Involved
Related Wireless Network Models
The Research Problem
Link Layer Issues
Mobile MAC Issues
Protocols for Wireless Sensor Networks
Multihop Routing
Cooperative Signal Processing
Conclusion
Wireless Sensor Network – A General Scenario
Internet
Wireless Sensor Network
TargetSensor Node
Sink Node
User
Sensor
Actuator In
terf
ac
e
Signal processing for event detection
Control
Processing
Event Classification
and identification
Wireless networkinterface
WINS Sensor Node Architecture
Design Challenges Involved
Hardware MEMS Sensor Technology Digital Circuit Design & System Integration Designing Low-power RF front-end and circuitry
Wireless Networking Robust & Energy-Efficient Communication Channel Access, Routing, Mobility Management
Applications Detection, Data Collection & Signal Processing
Related Wireless Network ModelsMobile Ad hoc Network
Cellular Network
Mobile NodeWireless link
Mobile Cluster Head
Wired link
Wireless link
Mobile User
Stationary Base Station
Research Problem
Energy Consumption – sensing, data processing and
communications
Communications in a network consumes lot of energy
Trade-off between data processing and wireless
communications
More local processing done in sensors
Message overhead should be reduced
Need For Highly Localized And Distributed
Algorithms For Data Processing And Networking
Link Layer Issues
Formation of topology & Channel Access
Contention/ Explicit Organization based Channel Access
TDMA/FDMA/CDMA schemes
Transceivers have to monitor channels at all times
Expensive in the context of sensor networks
Organized Channel Access
Discover neighbors and then assign collision-free channels
Hierarchical structure
Network-wide Synchronization
Centralized / Distributed Channel Assignment
Mobile MAC Issues
Provides connectivity to mobile sensors as they interact with
static networks
It has to adhere to the stationary network constraints
Mobility Management
MANET – Through Mobile Cluster Heads
Cellular Network – Hand-off Techniques by Base stations
Sensor Networks
Consists of mobile nodes and stationary nodes
Must focus on energy consumption than anything else
What is the Mechanism/Algorithm to handle mobility????
Protocols that perform ORM Network Start up & Link layer organization
SMACS (Self-Organizing Medium Access Control for Sensor Networks)
Stationary Wireless Nodes and Mobility Management EAR (Eavesdrop-And-Register) algorithm
Multihop Routing SAR (Sequential Assignment Routing) algorithm
Signaling & Data Transferring SWE (Single Winner Election) algorithm MWE (Multi-Winner Election) algorithm
SMACS It is an infrastructure building, distributed protocol that forms
a flat topology Neighbor discovery and channel assignment phases are
combined TDMA slots are assigned to links and then they operate on
different frequencies To reduce likelihood of collisions
AD
C
B
F
Link-layer self-organizing procedure
TYPE
1
TYPE1
TYPE2
TYPE
2
TYPE
3
TYPE3
TYPE4Initial listening
time
Node B
Node C
D and A find each other
B and C find each other
Trans. SLOT
Rec. SLOT
Td
Ta
fx fx
fx fx
Tb
Tc
fy
fy
T frame
Node D
Node A
Node B
Node C
EAR Algorithm A Typical Wireless Sensor Network
Attempts to offer continuous service to these mobile nodes under both mobile and stationary constraints.
Adheres to mobile nodes’ limited power constraints within the stationary network
Mobility Management
Wireless link
Mobile sensor
Stationary sensor
Signaling Method Broadcast Invite (BI)
Stationary node transmits invitation to surrounding neighbors –Stationary MAC protocol
Mobile node extracts SNR, node ID, transmitted power etc and holds it in the registry
Mobile Invite (MI) Mobile node responds to BI to request a connection
Mobile Response (MR) Stationary node accepts the connection and selects the slots for
communication Adds it to the registry
Mobile Disconnect (MD) Disconnection of nodes are determined through predefined thresholds
Timeouts for limiting errors
Routing
Multihop Routing
AODV (Ad Hoc On Demand Distance Vector)
TORA (Temporally Ordered Routing Algorithm)
Power –Aware Routing Algorithm
Minimum energy/packet
Minimum cost/packet
SAR Algorithm
Path Selection – Energy Resource, QoS , Priority of Packet
Minimizes average weighted QoS metric
Focus on High
Mobility
Focus on Energy
Efficiency
Cooperative Signal Processing
A form of hierarchical information processing where raw sensor
data is first collected and processed by individual nodes to
generate a parametric or filtered version of the original data,
and later gathered at a single location for combined processing.
Eliminates the communication cost for relaying the raw data to
some entity outside of the sensor network for processing.
Adaptive Local Routing Algorithm (SWE, MWE)
Coherent and
Non-Coherent event-based cooperative signal processing.
Noncoherent Cooperative Function
Raw data is often parameterized and or highly compressed
Data traffic is lower
Energy minimization is best achieved by reducing the overhead in the algorithm itself.
Communication cost can be significantly reduced
Processing Network Formation
• Target Detection• Data Collection• Preprocessing
Phase 1
• Membership Declaration
Phase 2
• Central Node Election
Phase 3
SNR (Signal to Noise Ratio)
SWE ,ST
algorithm
SWE Algorithm
Routing information & Election information is piggybacked on the
Elect message so that a minimum-hop spanning tree can be built
from each sensor node to the eventual winner(s) of the election
Overhead-Delay Tradeoff
By the end of the SWE process, a minimum-hop spanning tree will
completely cover the network.
ST Algorithm
The routing algorithm computes a minimum-hop spanning
tree connecting each participating sensor to the winner(s)
of the election.
No additional complexity is added to the algorithm
complexity
Ultimately shortens the duration of the entire network
routing algorithm
Also cuts overhead by compressing election and routing
information into a single message.
Coherent Cooperative Function
Raw data is only mildly filtered before combined processing takes place
Data traffic is higher
Communication cost associated with relaying long data streams can be prohibitively high because of energy resource limitation
Focus is on finding the optimal processing node and the minimum energy routes.
MWE Algorithm
Limits the number of sensor nodes that provide data
Each node will now keep up to n of the best candidates
At the end of the MWE process, each sensor in the network has a set of minimum energy path to each SN
Total energy consumption to upload data from each SN to each node is computed
Formation Process for Coherent Routing
Test Simulation Implementation The simulation environment models each node as a
separate Parsec entity. The functionality of each layer, namely MAC, mobile MAC,
and the network layer, is implemented as a function inside the node.
Conclusion The algorithms exploit the low mobility and abundant
bandwidth, while coping with the severe energy constraint and the requirement for network scalability.
THANK YOU..
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