L. Giarré, Dipartimento di Ingegneria dell'Automazione e dei

Location :

INRIA-Rocquencourt
Dans la salle de conférence du bâtiment 11 
Domaine de Voluceau - Rocquencourt
78153 Le Chesnay Cedex

Abstract :

In Wi-Fi networks, mobile nodes compete for accessing the shared channel by means of a
random access protocol called Distributed Coordination Function (DCF), which is long term fair.
But recent drivers allow users to configure protocol parameters differently from their standard
values in order to break the protocol fairness and obtain a larger share of the available bandwidth
at the expense of other users. This motivates a game theoretical analysis of DCF.
Previous studies have already modeled access to a shared wireless channel in terms of non-
cooperative games among the nodes, but they have mainly considered ad hoc mode operation.
In this paper we consider the role of the Access Point (AP) in infrastructure mode operation, for
mitigating or discouraging such malicious behaviors. Solving a mechanism design problem, 
we use the AP as a network coordinator, for encouraging node strategies which maximize a 
global utility function. We analyze both unidirectional and bidirectional (uplink and 
downlink) traffic scenarios. In the first one it is known that nodes selfishness jeopardize 
performance, but we show that simple changes to AP operation can let the system achieve optimal 
performance in spite of nodes selfishness. Instead for the bidirectional scenario the legacy behaviour 
of an AP is sufficient to guarantee quasi optimal performance.

Host :

INRIA