lecture-7-cho_pte587_sensornet1-feb-24-2011

85 1386 1287 1188 1089 990 891 792 693 594

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: m 36 TDoA: Distance Calcula;on Radio Transmitter Time of of Arrival Time Arrival of Ultrasound is … TR of Radio is … U Radio Receiver ~ Distance Ultrasound Transmitter 3/2/11 Speed of Sound Ultrasound Receiver = Time Difference of Arrival USC  ­ PTE587 37 Ultrasound Ranging •  Measurement Pla{orm –  MICA motes –  Mote programming modules –  Ultrasonic ranging accessories –  AVR Development Environment –  Beacon and Arbiter code for AVR –  Sooware driver to collect data –  Ba|eries and cases 3/2/11 USC  ­ PTE587 38 TDoA with Ultrasound Paging Radio Transmitter Time of of Arrival Time Arrival of Ultrasound is … TR of Radio is … U When the Ultrasound IRadio Receiver is s received radio Sleeping awaken z Sender waits for DWimmediately aSo the radio is sent fter Ultrasound Transmission efore transmitting Radio ~bDistance Ultrasound is sent first Ultrasound Transmitter + 3/2/11 - Speed of Sound Ultrasound Receiver Listening = Time Difference of Arrival Because TU=T0+Tof_flight_of_Ultrasound and TR=T0+DW+[Tof_flight_of_Radio~0] TDoA=TU+DW-TR~Tof_flight_of_Ultrasound USC  ­ PTE587 39 Another Way? •  Modifica;ons –  Omni ­direc;onal with step motor? –  Reuse the steps for TDoA to save energy? •  Direc;onality based localiza;on –  Nasipuri 2002 –  Step ­motor with Ultrasound transducer –  Distance as well angular informa;on 3/2/11 USC  ­ PTE587 40 Data Aggrega;on •  Gradient Broadcast (GRAB) •  Basic Idea –  Flow of water from mountain to valley –  Gradient is setup from network to Sink 3/2/11 USC  ­ PTE587 41 Four major components of GRAB •  Cost field setup •  Density control –  Gradient toward Sink –  Min. cost forwarding •  Mesh Forwarding –  Complex protocol not feasible –  Use redundant paths –  Credit based control 3/2/11 –  Background process –  Min. nodes for area –  Sleep redundant nodes •  Cost field refresh –  Frequent changes –  Update cost field –  High service quality USC  ­ PTE587 42 Simplified GRAB Example > + Cost Budget: 9 10 =9 Cost: 5 9 8 Center of Stimulus 8 5 6 4 3 ... Sink 3/2/11 USC  ­ PTE587 43 Problem to Think About 10 9 8 8 5 6 4 3...
View Full Document

Ask a homework question - tutors are online