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A Throughput-Adaptive MAC Protocol for Wireless Sensor Networks
Zuo Luo, Liu Danpu, Ma Yan, Wu Huarui
Beijing University of Posts and Telecommunications
Beijing, China
IEEE WiCOM 2010
Outline
• Introduction• System model• TA-MAC• Simulation• Conclusion
Introduction
• All medium access control (MAC) protocols for wireless networks try to make sure that no node should interfere with other nodes
Introduction
• An additional consideration for wireless sensor networks is to manage radio's activity to conserve energy
• While traditional MAC protocols must balance throughput, delay and fairness
Introduction
• Energy consumption on sensor– Collision– Overhearing– Idle listening
Introduction
• In recent research efforts, a duty cycle is used in sensor nodes to reduce energy waste caused by idle listening– S-MAC– T-MAC
Introduction
• S-MAC
active active active activesleep sleep sleep sleep
Time
active active active activesleep sleep sleep sleep
Sensor A
Sensor B
Introduction
• Drawbacks in S-MAC– Energy wasted– Packet dropped
Introduction
• T-MAC
Time
active active active activesleep sleep sleep sleepSensor A
Introduction
• Drawbacks in T-MAC– Packet latency– Packet dropped
Goal
• Propose a new TA-MAC protocol in this paper– Adaptive contention window– BS packet
System model
• Duty cycle and synchronization• Four way handshake• Active period (AP)
BSCSPRCWAP
Contention window
Transmission time of RTS
Transmission time of CTS
Short period between
RTS and CTS
Transmission time of BS
TA-MAC
• Adaptive contention window– Buffer threshold
2
WindowContention
TA-MAC
A
B
C
D
E
FTime
RTS CTS
CTS
RTS
RTS
CTS
A B C D E F
BS
BS
waitingBS
BS
PS
PS
DATA
DATA ACK
ACK
R
C
C
R
D
D A
A
R
C
C
R
D
D A
A
Simulation
• Simulation setup
Parameter Value
Topology 10 Line / 10*10 grid
Active period 20 ms
Frame length 650 ms
Data packet size 100 bytes
Transmitting energy 10 mA
Receiving and idle energy 4 mA
Sleeping energy 20 μA
Simulation result
• Line topology
Simulation result
• Line topology
Simulation result
• Grid topology
Simulation result
• Grid topology
Conclusion
• In this paper the authors proposed two new mechanisms to improve throughput and latency for WSNs
• The simulation results shows that TA-MAC protocol achieves significant trade-off on throughput and energy efficiency
21
Thanks for your at tention