BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Rate Adaptation Games in Wireless LANs: Nash Equilibrium and Price
  of Anarchy - Bozidar Radunovic\, Microsoft Research Cambridge.
DTSTART:20090211T160000Z
DTEND:20090211T170000Z
UID:TALK16151@talks.cam.ac.uk
CONTACT:Sarah Lilienthal
DESCRIPTION:In Wireless LANs\, users may adapt their transmission rates de
 pending on the observed radio conditions on their links to maximize their 
 throughput. Recently\, there has been a significant research effort in dev
 eloping distributed rate adaptation schemes offering better performance th
 an that of the current ARF (Automatic Rate Fallback). Unlike previous work
 s\, we characterizes the optimal reaction of a rate adaptation protocol to
  the contention information received from the MAC. We formulate this probl
 em analytically. We study both competitive and cooperative user behaviors:
  In the case of competition\, users selfishly adapt their rates so as to m
 aximize their own throughput\, whereas in the case of cooperation they aim
  at adapting their rates to maximize the overall system throughput. We sho
 w that the Nash Equilibrium reached in the case of competition can be inef
 ficient (i.e.\, the price of anarchy is high\, up to 50% of the social opt
 imum)\, and provide insightful properties of the socially optimal rate ada
 ptation schemes. We also show that RTS/CTS does not make the competitive s
 cenario more efficient. We then apply the same analysis to recently propos
 ed collision-aware rate adaptation algorithms and observe similar conclusi
 ons. Finally\, we propose a novel collision-aware rate adaptation algorith
 m that significantly reduces the price of anarchy in many scenarios of int
 erest.\n\nThis is a joint work with Prasanna Chaporkar and Alexandre Prout
 iere.
LOCATION:MR15\, CMS\, Wilberforce Road\, Cambridge\, CB3 0WB
END:VEVENT
END:VCALENDAR