05-10-2012, 01:38 PM
Routing
Routing protocols for Wireless Sensor Networks
The Main Goal of WSNS for Routing Protocols
Routing Metrics
Network Layer Responsibility
Flooding
Data Centric Routing
Proactive Routing
On-Demand Routing
Hierarchical Routing
Location Based Routing
QoS-Based Routing
Goal of WSNs Routing Protocols
To Develop Energy efficient routing strategies to transfer sensor data from nodes to sinks for the purpose of maximizing the lifetime of WSNS
Network Layer Responsibilities
Direct Communication model:- Energy sensors communicates directly(single hop) with the sink device(base station)
Multi-hop communication model:- sensors co-operate in propagating sensor data towards the sink
Network Organization:-
Flat: All nodes are “equal”
Hierarchical: Different roles for different nodes
Location Based: Nodes rely on location information
Route Discovery:-
Reactive(on-demand):Find Route only when needed
Proactive: Establish Routes before they are needed
Hybrid: Protocols with reactive and proactive characteristics
Flooding and Gossiping
Flooding:-
Every sensor (re-)broadcasts sensor data to all of its neighbors
Sensor broadcasts every packet it receives
Relay of packet till the destination or maximum no of hops
No topology maintenance or routing
Gossiping:-
Enhanced version of flooding
Sends received packet to a randomly selected neighbor
Problems of implosion, resource and blindness
Implosion: Nodes will re-broadcast even when neighbors already have a copy
Overlap: Sensor data contains redundant information
Resource Blindness: Resource constraints are ignored, Resource constraints of individual nodes
Direct Diffusion:-
Data-Centric and application-aware dissemination protocol
Nodes request data by sending interests for named data(data is named by attribute-value pairs)
Interest dissemination sets up gradients within network to direct sensor data toward recipient
Intermediate nodes along the paths can combine data from different sources
Eliminates redundancy
Reduce number of transmissions