Using Directional Antennas for Medium Access Control in Ad Hoc Networks Romit Roy Choudhury, Xue Yang, Ram Ramanathan. and Nitin H. Vaidya University of lllinois at Urbana-Champaign MOBICOM 2002
Outline Introduction Problems with Basic DMAC Multi-Hop RTS MAC Protocol Simulation Future work & Conclusion
Introduction Antenna Model Assumed antenna system Omni antenna Tx/Rx from all directions (360 degrees) Directional antenna Can point its main lobe towards any specified direction Do not consider power control Fixed beamwidth
Introduction Antenna Model A Directional modeOmni mode B Benefits of directionality Spatial reuse Higher transmission range
Problems with Basic DMAC Hidden terminal problems Hidden terminal due to asymmetry in gain BE FA RTSCTSDATARx RTS
Problems with Basic DMAC Deafness A B DC DATA
Multi-Hop RTS MAC Protocol Protocol Description : Multi-Hop RTS Direction-Omni (DO) Neighbor Direction-Direction (DD) Neighbor CD TXRX DD Neighbor C D TX RX DO Neighbor
CTS RTS Multi-Hop RTS MAC Protocol D G B RTS F C RxDATA RX A
Simulation Results
Simulation
Future Work & Conclusion Rely less on the upper layers for beamforming information Replace the omni mode operation (tone) Performance of the system improve in terms of aggregate throughput and end- to-end delay
Thank You !!
Problems with Basic DMAC Hidden terminal problems Hidden terminal due to unheard RTS/CTS D BF E DATA RTS CTS DATA