Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Systems Science

2 Konorski J.

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: ad hoc WLAN

Sortuj według:

Ogranicz wyniki do:

IEEE 802.11 LAN capacity : incentives and incentive learning

Konorski J.

Systems Science

2007

Vol. 33, no 4

111-118

For an ad hoc IEEE 802.11 WLAN we investigate how stations' noncooperative behavior in the form of a backoff attack (configuring small minimum and/or maximum CSMA/CA contention windows at some stations in pursuit of a large goodput share) affects a proposed realistic network capacity measure. We argue that such a measure should reflect both the total goodput and fairness, to factor in contention overhead and favor sustainable, i.e., fair, scenarios where each station pursues a large goodput share. Therefore, we consider a capacity-fairness index (CFI), the product of total goodput and the Jain index of the stations' goodput shares. If the backoff mechanism is mandatory, the CSMA/CA game that arises has a unique Nash equilibrium. In the opposite case there is no compelling outcome; we envisage that a station then calculates backoff attack incentives to predict imminent play. We link CFI to the network size, "power awareness", a stations perception of the other stations' susceptibility to incentives, and the way of learning how the stations perceive the other stations' susceptibility to incentives. We show that noncooperative behavior reduces CFI more than does contention overhead, yet if the stations are few and "power aware" enough then its impact may be lessened.

QoS provisioning in a single-cell ad hoc WLAN via queuing and stochastic games

Konorski J.

Systems Science

2006

Vol. 32, no 3

69-77

Selfish manipulation of the binary exponential backoff scheme in an ad hoc IEEE 802.11 WLAN leads to a noncooperative CSMA/CA game with a payoff structure characteristic of a multiplayer Prisoners’ Dilemma. For a simple QoS sensitivity model, assuming elastic traffic flows with a minimum bandwidth share requirement R, we modify the payoffs to define a QoS game. In an ideal scenario, WLAN stations take actions (switch to selfish play) sequentially, in which case for R large enough the game changes into a queuing game with multiple unfair Nash equilibria. Even if the stations are allowed to act simultaneously, these equilibria predict the outcome of the QoS game fairly accurately, depending on the schedule and limits on the number of actions. However, a station can selfishly depart from a common schedule of actions; to account for that, we propose a Markovian stochastic game model and prove the existence of a fair Markov perfect Nash equilibrium.