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Influence of Transmission Power on the Performance of Ad Hoc Networks. Crystal Jackson SURE 2004. Outline. Intro Overview of major protocols Model Results Conclusion and Future Work. What is an Ad Hoc Wireless Network?. Collection of self configuring wireless nodes No infrastructure
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Influence of Transmission Power on the Performance of Ad Hoc Networks Crystal Jackson SURE 2004
Outline • Intro • Overview of major protocols • Model • Results • Conclusion and Future Work
What is an Ad Hoc Wireless Network? • Collection of self configuring wireless nodes • No infrastructure • Simple example:
How They Work • Multi-hop environment source destination
Signal vs. Interference • EINR (energy to interference plus noise ratio) EINR = N PO TC PITc + No where PO = PTL(d) and PI = ΣPRL(di) L(d) = λ (path loss formula) 4πd Received energy Noise Interference i α
Major Protocols • Slotted time system • Channel access protocol • RTS/CTS/DATA/ACK rules • Exactly one RTS • received • EINR > threshold • Packet received • EINR > threshold • CTS received • EINR > threshold • Check for ACK A B CTS ACK RTS 1 Time Slot RTS CTS DATA ACK
Major Protocols • Network Layer • Queue • First in First Out • Maximum limit of 50 packets • Routing • Dijkstra’s algorithm to calculate routes with fewest relays • Radius calculated using EINR threshold • Packet Generation • Each node generates a packet in a slot with probability p • Randomly selected destination for packet
Model • Input File • Number of nodes • Size of the field • Duration of simulation • Spreading factor (value N in EINR calculation) • Generation rate and • Transmission power of a node
Model • Nodes placed at random locations • Simulation averaged for 10 trials • Performance measures • Completion Rate – packets received/packets generated • Throughput – packets received/slot • Delay – slots/packet received • Throughput Efficiency- packets received/unit of energy
Results • Model • Number of nodes: 100 • Area: 14638m x 14638m • Duration: 30000 time slots • Spreading factor: 128 • Generation rate: 0.001 to 0.030 packets/slot • Frequency: 1 GHz • Transmission power: vary
Transmission Powers Used Diameter = 2 Diameter = 3
Completion Rate According to Variations in Transmission Power
Throughput Efficiency According to Variations in Transmission Power
Conclusion • Higher transmission powers preferred • Advantages • Higher completion rate • Higher throughput • Lower delay • Disadvantage • Lower energy efficiency • Lack of enough power for small devices
Future Work • Short-term • Varying spreading factor • Packets requiring multiple slots for delivery • Long-term • Model with adaptive transmission powers • Low transmission powers for lower generation rates • High transmission powers for higher generation rates
Acknowledgements • Dr. Russell • SURE Coordinators • Dr. Noneaker • Dr. Xu • NSF