Mote shrubs and herds

1
Mote shrubs and herds

• Thanos Stathopoulos
• Lewis Girod
• CENS/UCLA
• September 2004

2
Introduction

• Tiered systems are becoming a reality
• Simulation/emulation EmStar EmTOS
• Hardware Motes stargates
• Existing deployments
• James Reserve
• 2 stargates
• tens of motes
• NIMS/JR
• One mobile PC104 (NIMS node)
• Several motes

3
An example Flexible image triggering

• Collection of microservers
• Steerable cameras attached
• Collection of motes with environmental sensors
• Mote detecting an event can cause multiple
  cameras to activate
• Single mote cannot reach/cover all points of
  interest
• Short-range radio
• Limited sensor range
• Lack of more 'global' view
• Limited storage

4
Solution Microservers

• Microservers have ample storage
• A global view can be created
• 'Mote coverage' knowledge
• 'Camera field of view' knowledge
• Need to build an 'association' of motes to
  cameras
• Useful for both initial configurtion as well as
  run-time operation/maintenance
• Not necessarily equivalent to network
  relationship
• Can change over time (obstructions)

5
Mote herding

• A set of tools and services
• Microservers 'control' motes
• Allows applications to seamlessly use available
  hardware infrastructure
• 'Masks' resource heterogeneity under common
  abstractions

6
Mote Herding Goals

• Leverage computational power of microservers
• Take advantage of higher quality state view
• Temporal resolution (lots of storage)
• Spatial resolution (data from several motes)
• Data fusion point
• Create a logical association between
  heterogeneous components
• E.g. mote sensor coverage and camera coverage
• Provide higher-level services that applications
  can use

7
Required capabilities

• Microserver coordination
• Based on input from sensors as well as state
  exchanges
• System monitoring
• Microservers must monitor their motes as well as
  other microservers
• Mote handoff
• When needed, a mote must change 'herders'
• Reliable state synchronization
• Required for coordination, monitoring and handoff
• Custody transfer
• Motes need to reliably transfer custody of their
  data to their herders

8
Other applications for Mote Herding

• Mote herding can be useful to other applications
  that take advantage of tiered architectures
• Possible examples
• Habitat monitoring
• Distributred medical monitoring
• Acoustic colalborative signal processing
• Moving object tracking