1. A Survey on Routing Protocols for Wireless Sensor NetworksBy
Vinay Kumar Singh
Dongseo University

2. Table of Contents Introduction System Architecture & Designing
Protocols for Sensor Networks
Next Plan
Summary

3. Introduction - Routing
No global addressing
Redundant data traffic
Multiple-source single-destination network
Careful resource management
Transmission power
On-board energy
Processing capacity
Storage

4. System Architecture & Designing
Network Dynamics
Mobile or Stationary nodes
Static Events (Temperature)
Dynamic Events ( Target Detection)
Node Deployment
Deterministic – Placed manually
Self-organizing – Scattered randomly

5. System Architecture & Designing
Energy Considerations
Direct vs Multi-hop communication
Direct Preferred – Sensors close to sink
Multi-hop – unavoidable in randomly scattered networks
Data Delivery Models
Continuous
Event-driven
Query-driven
Hybrid

6. System Architecture & Designing
Node Capabilities
Homogenous
Heterogeneous
Nodes dedicated to a particular task (relaying, sensing, aggregation)
Data Aggregation/Fusion
Aggregation – Combination of data by eliminating redundancy
Data Fusion is Aggregation through signal processing techniques
Aggregation achieves energy savings

7. Introduction - Taxonomy
Classification of Routing Protocols
Data Centric
Hierarchical
Location-based
Network Flow & QoS Aware

8. Data-centric Protocols
Sink sends queries to certain regions and waits data from sensors located in that region
Attribute-based naming is necessary to specify properties of data

9. Data-centric Protocols
Flooding
Gossiping
Sensor Protocols for Information via Negotiation (SPIN)
Directed Diffusion
Energy-aware Routing
Rumor Routing
Gradient-Based Routing (GBR)
Constrained Anisotropic Diffusion Routing (CADR)
COUGAR
Active Query forwarding In sensor networks (ACQUIRE)

10. Data-centric Protocols
Flooding
Sensor broadcasts every packet it receives
Relay of packet till the destination or maximum number of hops
No topology maintenance or routing
Gossiping
Enhanced version of flooding
Sends received packet to a randomly selected neighbor

11. Data-centric Protocols – Flooding, Gossiping Problems
Problems of Implosion, Overlap, Resource Blindness

12. Data-centric Protocols
Sensor Protocols for Information via Negotiation (SPIN)
Uses meta data and high level descriptors to name the data

13. Data-centric Protocols
Directed Diffusion
Uses a naming scheme for the data to save energy
Attribute-value pairs for data and queries on-demand (Interests)
Interests are broadcasted by the sink (query) to its neighbors (caching), which can do in-network aggregation
Gradients = reply links to an interest (path establishment)

14. Data-centric Protocols – Direct Diffusion
Energy saving and delay done with caching
No need for global addressing (neighbor-to-neighbor mechanism)
Cannot be used for continuous data delivery or event-driven applications

15. Data-centric Protocols
Energy-aware Routing
Occasional use of a set of sub-optimal paths
Multiple paths used with certain probability
Increase of the total lifetime of the network
Hinders the ability for recovering from node failure
Requires address mechanism Complicate setup
The optimal path is not used all the time ….

16. Data-centric Protocols
Rumor Routing
Variation of Directed Diffusion
Flood the events instead of the queries
Creation of an event  generation of a long live packet travel through the network (agent)
Nodes save the event in a local table
When a node receives query  checks its table and returns source – destination path

17. Data-centric Protocols – Rumor Routing
Advantages
Can handle node failure
Significant energy savings
Disadvantages
Works well only with small number of events
Overhead through adjusting parameters, like the time to live of the agent
Big number of events mean event tables to big and big cost for maintaining agents

18. Data-centric Protocols
Active Query forwarding In sensor networks (ACQUIRE)
Views network as a distributed database
Node receiving a query from the sink tries to respond partially and then forwards packet to a neighbor
Use of pre-cached information
After the query is answered, result is returned to the sink by using the reverse path or the shortest path
If cache information is not up to date  node gathers information from neighbors within look ahead of d hops

19. Data-centric Protocols – ACQUIRE
Motivation: Deal with one shot complex queries
Efficient routing by adjusting parameter d
If d equals network size  behaves similar to flooding
If d too small the query has to travel more hops

20. Hierarchical Protocols
Maintain energy consumption of sensor nodes
By multi-hop communication within a particular cluster
By data aggregation and fusion  decrease the number of the total transmitted packets

21. Hierarchical Protocols
LEACH – Low-Energy Adaptive Clustering Hierarchy
Power-Efficient Gathering in Sensor Information Systems (PEGASIS)
Hierarchical PEGASIS
Threshold sensitive Energy Efficient sensor Network protocol (TEEN)
Adaptive Threshold TEEN (APTEEN)
Energy-aware routing for cluster-based sensor networks
Self-organizing protocol

22. Hierarchical Protocols
LEACH – Low-Energy Adaptive Clustering Hierarchy
One of the first hierarchical routing protocols
Forms clusters of the sensor nodes based on received signal strength
Local cluster heads route the information of the cluster to the sink
Cluster heads change randomly over time  balance energy dissipation
Data processing & aggregation done by cluster head

23. Hierarchical Protocols - LEACH
Advantages
Completely distributed
No global knowledge of the network
Increases the lifetime of the network
Disadvantages
Uses single-hop routing within cluster not applicable to networks in large regions
Dynamic clustering brings extra overhead (advertisements, etc)

24. Hierarchical Protocols
Power-Efficient Gathering in Sensor Information Systems (PEGASIS)
Improvement of LEACH
Forms chains from sensors rather than clusters
Data aggregation in the chain  one node sends the data to the base station
Outperforms LEACH
Excessive delay for distant nodes in the chain
Outperforms LEACH  we don’t have the overhead of the cluster formation

25. Hierarchical Protocols
Hierarchical PEGASIS
Extension of PEGASIS
Decrease the delay for the packets during transmission to the base station
Solution to the delay data gathering problem
Simultaneous transmissions of data messages
Avoid collisions and possible signal interference
Signal Coding (e.g. CDMA)
Spatially separated nodes can transmit at the same time

26. Hierarchical Protocols

27. Hierarchical Protocols
Energy-aware routing for cluster-based sensor networks
Assumptions:
Sensors are grouped into clusters prior to network operation
Cluster Heads (Gateways) less energy constrained
Cluster Heads know the location of the sensors  Known Multi-Hop routing to collect data
Communication node (sink) communicates only with gateways

28. Hierarchical Protocols
Stages of a Sensor inside a cluster
Sensing only
Relaying only
Sensing-Relaying
Inactive

29. Hierarchical Protocols
Least Cost path used between nodes and gateway
Cost function
Energy Consumption
Delay Optimization
Performance Metrics
TDMA based MAC is used for nodes to send data to the gateways
Protocol performs well for
Energy-based metrics (e.g. network lifetime)
Cotemporary metrics (e.g. throughput)

30. Hierarchical Protocols
Self-organizing protocol
Architecture supports heterogeneous sensors
Nodes act as routers  backbone of communication
Stationary
Sensing nodes forward data to the routers
Mobile
Sensors are a part of the network if they are reachable by a router

31. Hierarchical Protocols
The architecture requires addressing
Sensor identified by the router is connected to
Algorithm for Self-Organizing & Creation of routing table
Discovery phase
Organization phase
Maintenance phase
Self-reorganization phase
Utilizes router nodes to keep all sensors connected by forming a dominating set

32. Hierarchical Protocols
Advantages
Useful for applications which need communication of a specific node (e.g. parking-lot networks)
Small cost of maintaining routing tables
Keeping routing hierarchy strictly balanced
Energy Savings – Utilization of a limited subset of nodes
Disadvantages
Organization phase not on demand
Many cuts in the network increase the probability of applying reorganization phase

33. Location-based Protocols
Distance between two nodes is calculated using location information
Energy consumption can be estimated
Efficient energy utilization
Protocols designed for Ad hoc networks with mobility in mind
Applicable to Sensor Networks as well
Only energy-aware protocols are considered

34. Network Flow & QoS-aware Protocols
Network Flow: Maximize traffic flow between two nodes, respecting the capacities of the links
QoS-aware protocols consider end-to-end delay requirements while setting up paths

35. Network Flow & QoS-aware Protocols
Maximum Lifetime Energy Routing
Maximum Lifetime Data Gathering
Minimum Cost Forwarding
Sequential Assignment Routing
Energy Aware QoS Routing Protocol
SPEED

36. Maximum Lifetime Energy Routing
Maximizes network lifetime by defining link cost as a function of:
Remaining energy
Required transmission energy
Tries to find traffic distribution (Network flow problem)
The least cost path is one with the highest residual energy among paths

37. Summary

38. Next Plan
I will study on how to simulate the effective sensor network outing protocols.
Mainly there are two type of routing protocols are used
Direct Diffusion
SPIN
I will try to go in detail of this protocol and than simulate using network simulator2.