Data Communication
Data Communication
Introduction
Motivation
Sensor network characteristics
Limited energy resources
Transient nodes and links
Mobility?
No network infrastructure
Indefinite network size
Data communication?
Limited communication range
Collaborating intermediate nodes required
Desirable property
Minimal control overhead
Delivery guarantees
Loop free operation
Good path quality
Source
Destination A
B
Delivery Guarantees
Definition: reachability
Definition: guaranteed delivery
Unicast
Multicast
Geocast
Anycast
Broadcast
Necessary condition: ideal MAC layer
Each message transmission is successful
Can be approximated by acknowledgement scheme
However, what about unidirectional links
However, sometimes messages just get lost
Delivery Guarantees by Flooding?
Pro
Simple
Works also for highly dynamic topology changes
Con
Lots of message duplicates
All nodes always involved
Loops have to be avoided
Redundant message transmissions
Broadcast storms
Memorization of sent messages
