This ppt gives an overview of the two routing protocols in the wireless sensor networks namely Rumor Routing and LEACH.

1. ROUTING IN
SENSOR NETWORKS
TEAM MEMBERS:
PALLAVI MEHARIA
AARTHI RAGHAVENDRA
ABHYUDAYA UPADHAYAY

2. OUTLINE
 Introduction
 Challenges and Design issues
 LEACH
 Rumor Routing
 Conclusion

3. Introduction
 Routing protocols differ in WSN based on the application and network
architecture.
 Based on the network structure, routing protocols are classified into three:
 Flat Routing – Same role is assigned to all the nodes
 Hierarchical Routing – Different roles are assigned to nodes
 Location based Routing – Position of the nodes are exploited to route
the data.
 Further classified into multipath-based, query-based, negotiation-based,
QoS-based, and coherent-based depending on the protocol operation.
 Trade off exists between energy consumption and communication
overhead.

4. Challenges and design issues
 Node deployment
 Manual Deployment
 Random Deployment
 Data routing methods
 Application-specific
 Time-driven: Periodic monitoring
 Event-driven: Respond to sudden changes
 Query-driven: Respond to queries
 Hybrid

5. Challenges and design issues
 Node link/ heterogeneity
 Homogeneous sensors
 Heterogeneous sensors
 Fault tolerance
 Transmission media
 Connectivity
 Coverage
 Data aggregation
 Quality of Service

6. Leach - Low Energy Adaptive Clustering
Hierarchy
 It is a hierarchical routing protocol that
suggests both hierarchical and
centralized schemes.
 Self-Organizing, adaptive clustering
protocol.
 Minimal setup time, even distribution of
energy load among the sensors thus
enhancing the lifetime of the network.
 Dynamic cluster formation.
 Randomized rotation of cluster heads
after each round.
 Cluster-heads communicate data with
the base station.
 Application-specific data processing,
such as data aggregation.

7. leach
 Each LEACH round consists of two phases:
 Set-up Phase
 Cluster head selection
 Cluster formation
 Steady-State Phase
 Cluster head maintenance
 Data transmission between nodes

8. Leach – Set up phase
 At the beginning of each round, each node advertises it probability to be the
Cluster Head, to all other nodes.
 Probability for each node i to be the Cluster-head at time t
where Ci(t) = determines whether node i has been a Cluster head in the most
recent rounds
 Higher the probability better are the chances to be chosen as the Cluster Head.

9. Leach – Set up phase
 Cluster Head broadcasts an advertisement message (ADV) using CSMA
MAC protocol.
 Based on the received signal strength of the ADV message, each non-
cluster head node decides its Cluster Head for that round.
 Each node transmits a join-request message (Join-REQ) back to its chosen
Cluster Head.
 Cluster Head node sets up the TDMA schedule for coordinating data
transmission with the cluster.
 Using TDMA schedule has two advantages:
 Avoid collision of data packets from different nodes within a cluster.
 Conserve energy in the non-cluster head nodes.

10. Leach – steady state phase
 Node uses the time slot assigned to it to transfer data to the cluster head.
 Cluster head aggregates the data received from all the nodes of the
cluster.
 Communication is via direct-sequence spread spectrum (DSSS) and each
cluster uses a unique spreading code to reduce inter-cluster interference.
 Intra-cluster communication uses TDMA and Inter-cluster communication
uses CDMA.

11. Rumor routing
 It is a flat routing protocol.
 Ensures network longevity, robustness in handling node failures.
 Intended to fill the region between query flooding and event
flooding.
 Transmits data packets through random paths rather than shortest
path.
 Event – Abstraction of a localized phenomena occurring in a fixed
region of space.
 Query – Information of interest to be retrieved.

12. Rumor routing
 Each node maintains a list of neighbors and its event table.
 When a node witnesses an event, it adds it to its event table with
distance zero and generates an agent simultaneously.
 An agent is a long-lived packet, which travels the network,
propagating information about local events to distant nodes.
 Any node can generate a query, then forward the query in a
random direction to find the path. The query keep going until its TTL
expires or it intersects with the agent path leading it to the
destination event.
 If the node that originated the query determines the query died, it
can retransmit, give up or flood the query.

13. Rumor routing
 Basic scheme
 Each node maintain
 A lists of neighbors
 An event table
 When a node detects an event
 Generate an agent
 Let it travel on a random path
 The visited node form a gradient to
the event
 When a sink needs an event
 Transmit a query
 The query meets some node which
lies on the gradient
 Route establishment

14. Agent
• Set up path by
random walk.
• Aggregate paths.
• Optimize paths in the
network.

15. Agent
 Each agent carries a list of all
the events it encountered
along with the number of hops
to that event.
 Each node among the path
maintains a table of events,
the number of hops to that
event and the next node in the
path toward the event.

16. Agent
 A straightening algorithm is used when determining the agent’s next hop
 Agent maintains a list of recently seen nodes. When it decides the next
hop, it tries the nodes not in the list. When it passes a node, the node’s
neighbors are added to the list.
 A node that witnessed an event would generate an agent at a fixed
probability in the simulation
 The future work can do better by generating agents according to
number of events, event size and node density.
 For applications where events are temporal, the event table may have
an expiration timestamp associated with each event

17. Query
 A query can be generated at any time by any node.
 Before reaching the path, nodes forward queries using the same
straightening algorithm – keep a list of recently seen nodes and
avoid visiting them.
 Each query has a TTL to avoid looping routes. If the query dies, the
node originating the query detects the failure and decide to
retransmit it or flood the query.

18. References
1. Rumor Routing Algorithm for Sensor Networks
http://research.cens.ucla.edu/people/estrin/resources/conferences/2
002sept-Brainsky-Etrin-Rumor.pdf
2. Energy- Efficient Communication Protocol for Wireless Microsensor
Networks
http://pdos.csail.mit.edu/decouto/papers/heinzelman00.pdf
3. Introduction to Wireless and Mobile Systems by Dharma Prakash
Agarwal and Qing-An Zeng.

19. THANK YOU !
QUERIES ?