stem/IOT/Software Services.md

• Large number of heterogeneous devices
• Spread physically
• Ability to join and leave
• Process data in-network or send directly

Challenges

• Fault tolerance
  • Nodes can
    • Get damaged
    • Run out of power
    • Lose comms
  • Redundant deployment
• Lifetime
  • Limited energy supply
  • Replacing sometimes not practical
    • Underwater
    • Large/remote field deployments
  • Energy efficient a necessity
• Scalability
  • WSM can have lots of nodes
  • Architectures and protocols need to scale
• Densities
  • Density of network can vary
    • Granularity
    • Coverage
  • Different applications warrant different numbers
    • Range of nodes
    • Space and time requirement
  • Not necessarily homogenous density throughout
    • Need to handle this
• Programmability
  • Flexible nodes with changing tasks
  • Changeable programs during operation
• Maintainability
  • WSN and environment can change
  • Adaptable system
  • Changing operational parameters
    • To increase energy efficiency for example

Node Types

• Sensor
  • Low power
  • Sensing, memory, processor, radio
  • Resource-constrained
• Sink
  • Another sensor node
    • Or different wireless node
  • Normally more powerful/better resources
• Gateway
  • Bridge IoT and internet networks
  • More powerful
  • Can have
    • Service representation
    • Cache/storage
    • Discovery

Application Types

• Event detection
  • Reporting event occurrences
  • Reporting abnormalities
  • May need collaboration with other nodes
  • Defining events and classification difficult
• Periodic measurements
  • Sense something and report
  • Period is application-dependent
• Approximation and pattern detection
  • Sense messages in space and time
  • E.g. combine wind, light, heat to detect forest fires
• Tracking
  • Source of event is mobile
  • Event updates with location information