50 likes | 281 Views
Capture Sensing Simultaneous Access Exploiting the Capture Effect for Greater Spatial Reuse and Higher Bandwidth. What happens when 2 packets collide? What information can we collect during a collision? How good (bad) is CSMA?. PACKET A. PACKET A. PREAMBLE. PREAMBLE. PREAMBLE. PREAMBLE.
E N D
Capture Sensing Simultaneous AccessExploiting the Capture Effect for Greater Spatial Reuse and Higher Bandwidth
What happens when 2 packets collide? What information can we collect during a collision? How good (bad) is CSMA? PACKET A PACKET A PREAMBLE PREAMBLE PREAMBLE PREAMBLE PAYLOAD PAYLOAD PAYLOAD PAYLOAD PACKET B PACKET B A B Capture Effect CSMA At R1: Nothing! At R2: A R1 T1 R1 T2 C R2
Build a table of stronger-weaker neighbors Propagate tables? Packet format Eliminating hidden-terminal ? A C Capture Sensing Simultaneous Access • According to my table: • T2 < T1 -> OK to send • T3 > T1 -> NOT OK to send R1 T1 T2 T3 R2
Design space in spatial reuse (spectrum) CSMA vs CSSA vs No Carrier Sensing at all Protocol design Apriori vs adaptive 2nd tier tables TTS (CSMA-EX) RTS/CTS Bandwidth gain / (loss) under: Point-point Broadcast Low-power listening Network layer choice Simulation (matlab) Future Plans (winter break and spring semester) Choose best one Implementation Deployment Assessment Dissemination Status and Plan Questions or suggestions?