ETH Zurich – Distributed Computing – Sharing a Medium Between Concurrent Protocols Without Overhead Using the Capture Effect Michael König Roger Wattenhofer

Wireless Sensor Networks

? ? Priority Traffic – CSMA

Priority Traffic – Scheduling

The Capture Effect

The Capture Effect – Power Difference

The Capture Effect – Packet Timing Preamble SFD Len Payload... Time Preamble SFD Len Payload... (weaker) (stronger)

The Capture Effect – Packet Timing Preamble SFD Len Payload... Time Preamble SFD Len Payload µs (weaker) (stronger)

The Capture Effect – Packet Timing

Priority Traffic – Using the Capture Effect

Halfway Summary MethodAlarm DelayRegular Operation Impairment CSMAArbitrarily largeNone SchedulingBoundedConstant fraction Capture EffectNone *

Network Heterogeneity vs

Testbed Example

Network Heterogeneity

Layer 4 Layer 3 Layer 2 Layer dBm -70 dBm -75 dBm -81 dBm “Layer” Abstraction: Receiving

“Layer” Abstraction: Sending Layer 4 Layer 3 Layer 2 Layer 1

“Layer” Abstraction Layer 4 Layer 3 Layer 2 Layer 1

“Layer” Abstraction: Caveat Layer 4 Layer 3 Layer 2 Layer 1

Feasible number of layers vs

Summary Layer 4 Layer 3 Layer 2 Layer 1

ETH Zurich – Distributed Computing – Questions Michael König

Backup Slides

Layer 1 - Convergecast