An Energy-Aware Medium-Access-Control Protocol with Frequent
Sleeps for Wireless Sensor Networks
Christopher K. Nguyen And Anup Kumar
Mobile Information Networks & Distributed Systems LabDepartment of Computer Engineering & Computer Science
University of Louisville
IEEE Symposium on Computers and Communications (ISCC 2005)
Speaker: Yung-Ling Yu
Outline
• Introduction
• TEA-MAC protocol design– Simplified version of 802.11 MAC frames– Radio modes and sensor states– The complete TEA-MAC scheme
• Evaluations and simulation results
• Conclusion
Introduction
• WSN require that the energy consumption in sensors should be as low as possible
• Saving energy always compromises the utilization and performance of WSN
• The Throughput and Energy-Aware MAC(TEA-MAC) focuses on – High throughput utilization of WSN– Ensuring low consumption of energy
Introduction
• The proposed protocol has two main contributions– Wake up as soon as a communication is requested
• Because just-in-time wake-ups reduce latency
– Sleep as soon as it becomes idle• Because instant sleeps reduce consumption of energy
TEA-MAC protocol design
• The proposed scheme alleviate– Idle listening– Control-packet overhead– Overhearing
• Using two main issues– Frequent sleeps
• Minimize idle listening
• Reduce overhearing
– Short sleeps• Maximize the throughput by reducing latency
Simplified version of 802.11 MAC frames
• For WSN, the prevalent communication is broadcast
• The overhead problem grows significant when the broadcast data propagate
• The shaded regions create unnecessary overhead – Every node is the recipient of the transmission
Simplified version of 802.11 MAC frames
• From inspection of the 802.11 data frame– The wastage percentage is
• (4*6)/(2+2+6+6+6+2+6+2312+4) = 1.02 %
• From inspection of
the 802.11 control frame– The wastage percentage is
1.for RTS
(2*6)/(2+2+6+6+4) = 60%
2.for CTS or ACK
6 / (2+2+6+4) = 42.86%
Radio modes and sensor states
• Three radio modes– Sleep– Receive– Transmit
Radio modes and sensor states
• Two sensor states– Sleep– Awake
The complete TEA-MAC scheme
The complete TEA-MAC scheme
The complete TEA-MAC scheme
Evaluations and simulation results
• Simulator– SENSE(Sensor Network Simulation and Emulator)
• 500 sensor nodes• Communication types
– Broadcast, multicast, and unicast mixed– Broadcast and unicast intervals were set at 5s and 1
0s, respectively
• The power– Transmission 1.6W– Reception 1.2W– Idle listen 1.15W
Evaluations and simulation results
Evaluations and simulation results
Conclusion
• TEA-MAC is a practical approach for two reasons– First, sensors are inexpensive
• It is not cost-ineffective to deploy sensors in great numbers
– Second, Technological advances provide sensors with much longer life
• The problem of energy consumption will eventually be less significant
