Must see data for beginners on WSN projects

1. Implementation and Improvement of
LEACH Protocol for Wireless Sensor
Networks
Saurabh Goel Dept. of IT, Jaypee University of IT
Abstract
In Wireless Sensor Networks, a node may be self-powered and discrete node have
the proficiency to intellect and interconnect. Becausesensors haverestricted
battery power, energy efficient routing is vital. In this paper, we implement
sensor routing scheme LEACH and clustering model in LEACH protocol. Leach is
one of the fundamentalprotocols in the clustering technique hierarchical routing
protocols that can be used for hindering the energy consumed in gathering and
distributing data. The paper will be concluded by mentioning the observations
made fromscrutiny of results about these protocols.
Introduction
Low Energy Adaptive Clustering Hierarchy ("LEACH") is a TDMA-based MAC
protocol which is integrated with clustering and a simple routing protocol in
wireless sensor networks (WSNs). Thegoal of LEACH is to lower the energy
consumption required to create and maintain clusters in order to improvethe life
time of a wireless sensor network.

2.  Sensor Network Challenges
 Limited communication bandwidth
 Limited energy
 Parameters (Design goals)
o Ease of deployment
o System lifetime
o Latency
o Quality
 Neighboring nodesmay have samedata
 End user cares about a higher-level description of events
 Techniques (to achieve the design goals)
o Randomized, adaptive, self-configuringcluster formation.
o Localized controlof data transfers
o Low energy mediaaccess control (MAC)
o Application specific data processing, such as data aggregation and
compression.
LEACH in brief
o Randomized rotation of cluster heads amongthe sensors
o All non-cluster head nodestransmitdata to their cluster head
o CH receives this data and performssignal processing
o functionson the data and transmits data to the BS

3. Cluster Formation Algorithm
 Cluster Heads broadcasts an advertisementmessage (ADV) using CSMA
MAC protocol.
 ADV= node’s ID + distinguishable header.
 Based on the received signalstrength of ADV message, each
non-Cluster Head node determines its Cluster Head for this
round.
 Each non-Cluster Head transmits a join-requestmessage(Join-REQ) back to
its chosen Cluster Head using a CSMA MAC protocol.
 Join-REQ = node’s ID + cluster-headID + header.
 Cluster Head node sets up a TDMA schedulefor data transmission
coordination within the cluster.
 TDMA Schedule
 Prevents collision among data messages.
 Energy conservation in non cluster-head nodes.

4. Steady State Phase
 TDMA scheduleis used to send data fromnode to cluster head.
 Cluster head aggregates the data received fromnodes in the cluster.
 Communication is via direct-sequencespread spectrum(DSSS) and each
cluster uses a unique spreading code to reduce inter-cluster interference.
 Data is sent fromthe cluster head nodes to the BS using a fixed spreading
code and CSMA.
 Assumptions
 Nodes are all time synchronized and startthe setup phase at same
time.
 BS sends out synchronized pulses to the nodes.
 Cluster Head mustbe awake all the time.
 To reduce inter-cluster interference, each cluster in LEACH communicates
using direct-sequence spread spectrum(DSSS).
 Data is sent fromthe cluster head nodes to the BS using a fixed spreading
code and CSMA.
Time line showing Leach Operation

5. Flow chart for steady state phase
Conclusion
 Microsensor network protocols mustbedesigned for
 Bandwidth efficiency
 Energy efficiency
 High quality
 LEACH
 Better energy utilization and systemlifetime
 Load balancing is achieved
 All nodes die at a time