Distributed coalitional game for friendly jammer selection in ultra-dense networks

Abstract

Consider an ultra-dense heterogeneous network with one malicious eavesdropper intercepting macro-layer information. A portion of small-cell base stations (SBSs) acts as the friendly jammer to help improving macro-users’secrecy rate by transmitting interference signal on the wiretap channel. In return, the client macro-user pays to its jammers for the jamming power that they provide. Instead of transmitting noise as traditional jammers do, this paper proposes a modified spectrum leasing method, which allows SBSs to replace the thermal noise with their own traffic. This approach also permits the jamming SBSs to access extra spectrum in order to enhance the performance. In the considered scenario, the macro-user tries to find the SBSs that can mostly protect its confidential message, while each SBS decides whether to serve as a jammer or not. Once an SBS decides to be a jammer, it needs to choose the optimal client macro-user depending on the channel condition. This two-way selection problem between SBSs and macro-users is modeled as the coalition formation game with non-transferable utility, and a distributed scheme is proposed for this game, in which the players (macro-users and SBSs) individually make a decision and converge to a Nash-stable partition in a self-organized manner. The simulation results show that the majority of macro-user equipments enjoy a fivefold increment in average secrecy rate and that the friendly jammer scheme effectively protects the macro-users from the eavesdropper. At the same time, the average capacity of small-cell layer also achieves a 16.92 % improvement.