Power Control in WLANs for Optimization of Social Fairness Vaggelis Douros Pantelis Frangoudis Konstantinos Katsaros George Polyzos {douros06,pfrag,ntinos,polyzos}@aueb.gr PCI 2008, 28/08/2008, Samos, Greece 7/12/2018

Motivation Some friends stay in the same neighborhood Each one has an AP Should they use Power Control for a fair and efficient distribution of their incomes?

Outline Prerequisites - Methodology Proposed Algorithms Performance Evaluation Variations Conclusions

Prerequisites Each AP belongs to a different owner 2 APs (3 APs) Using the same channel  interference Transmit at Pmax (i.e. maximum coverage radius) Each AP belongs to a different owner Goal: APs fully cooperate* for a fair and efficient distribution of their incomes Ν users (N=10, 30, 50,100) Uniformly randomly distributed Static – No arrivals/ volunteers departures

Methodology Custom simulator: C/ Matlab 10000 simulations for each scenario Income computation for each user i and each AP k

Algorithm FirstMax APs apply power control They simultaneously reduce their transmission power to the same level If, in the new state, the income for each AP is larger (worst case … equal) than the income in the previous state, power decrease continues Otherwise, they choose to transmit at the exact previous state Algorithm stops  First time there is a decrease to an AP’s income Find the first local maximum

Algorithm BestMax (1) APs apply power control They simultaneously reduce their transmission power to the same level Each AP computes its income Algorithm stops  APs have no common coverage area

Algorithm BestMax (2) Find the value of the transmission power ( Pmax) that maximizes the income of an AP, independently of the income of all other APs. Repeat the previous step for all APs of the topology. Find the value of the transmission power that the sum of the percentage losses from the maximum feasible incomes of each AP is minimized.

Income Comparison between FirstMax - BestMax

Mean % Improvement of FirstMax and BestMax with 2 ΑPs - 3 APs

Variations All APs of the neighborhood belong to me!.. Should I use power control? Non strict (not fully compliant) versions of these power control algorithms … “Bliss or curse?” Add a type of bargaining mechanism

Conclusions Back to the start… Some friends stay in the same neighborhood Each one has an AP Should they use Power Control for a fair and efficient distribution of their incomes? Of course! BestMax is a brilliant choice! Full and honest cooperation is rewarded!

Thank You! Vaggelis Douros Mobile Multimedia Laboratory Department of Informatics Athens University of Economics and Business douros06@aueb.gr http://mm.aueb.gr/~douros