Spatial Backoff in Wireless Networks Xue Yang Nitin
Spatial Backoff in Wireless Networks Xue Yang Nitin Vaidya University of Illinois at Urbana-Champaign Work-in-Progress Session, Sigcomm 2005 1
Medium Access Control g Shared wireless channel g Need mechanisms to resolve contention 2
Temporal Contention Resolution g Transmissions compete for time g Separate transmissions in time B A 3
Traditional View g Contention level a given g Adapt behavior to given contention level g Examples: Aloha Ethernet IEEE 802. 11 4
Alternate View: Spatial Contention Resolution g Transmissions compete for space Space “occupied” by a transmission can be controlled to control temporal contention 5
Controlling Temporal Contention A C B 6
Controlling Temporal Contention “Space” occupied by A A C Circular shape only for convenience B 7
B A 8
Controlling Temporal Contention A C B 9
B A B Smaller occupied space A 10
Spatial Contention Resolution g g Control occupied space by adapting transmit rate/power/carrier-sensing Goal: Occupied space Desired contention level 11
Implementing Spatial Contention Resolution g Example: Joint adaptation of transmission rate and carrier-sense threshold Adapting one parameter insufficient to suitably control space 12
For more information www. crhc. uiuc. edu/wireless nhv@uiuc. edu 13
- Slides: 13