Including Physical Layer Security in the Game Theoretic Modeling of Distributed Wireless Networks Operating in Unlicensed Frequency Bands

Wireless networks operating in unlicensed spectrum usually have to deal with signal interference, causing performance degradation. Most studies so far have tried to minimize interference to maximize users’ satisfaction. However, interference also has a positive effect: protection against eavesdropping attacks. In this study, we include Physical Layer Security (PLS) in the game-theoretical modeling of wireless networks operating in the unlicensed spectrum in a multi-operator environment without a centralized interference management authority. We do so by defining secrecy capacity as the utility of a non-cooperative game with multiple legitimate users and eavesdroppers, and using the mixed Nash equilibrium process to find optimal transmission powers. The key difference between the use of secrecy capacity as utility, as opposed to the commonly used Shannon capacity, is that secrecy capacity includes the effect that potential eavesdroppers have on the benign signal due to the necessary inclusion of secrecy-enhancing measures. We then show for a realistic scenario in a dense deployment how the utility changes if users demand performance under the condition of secrecy instead of merely maximum performance, and how that affects their transmission power selection strategy. Our experimental results reveal how a combined power selection strategy can be effective in preventing eavesdropping attacks.