Efficient contention resolution protocols for selfish agents

Amos Fiat, Yishay Mansour, Uri Nadav

Abstract: We seek to understand behavior of selfish agents accessing a broadcast channel. In particular, we consider the natural agent utility where costs are proportional to delay. Access to the channel is modelled as a game in extensive form with simultaneous play. Standard protocols such as Aloha are vulnerable to manipulation by selfish agents. We show that choosing appropriate transmission probabilities for Aloha to achieve equilibrium implies exponentially long delays. We give a very simple protocol for the agents that is in Nash equilibrium and is also very efficient --- other than with exponentially negligible probability --- all n agents will successfully transmit within cn time, for some small constant c.