1. Power Control in WLANs for Optimization of Social Fairness
Vaggelis Douros
Pantelis Frangoudis
Konstantinos Katsaros
George Polyzos
PCI 2008, 28/08/2008, Samos, Greece
7/12/2018

2. 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?

3. Outline Prerequisites - Methodology Proposed Algorithms
Performance Evaluation
Variations
Conclusions

4. 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

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

6. 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

7. 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

8. 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.

9. Income Comparison between FirstMax - BestMax

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

11. 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

12. 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!

13. Thank You! Vaggelis Douros Mobile Multimedia Laboratory
Department of Informatics
Athens University of Economics and Business