Physical Layer Security: Coalitional Games for Distributed Cooperation

TL;DR

This paper introduces a distributed coalitional game approach enabling wireless nodes to cooperatively enhance physical layer security, balancing secrecy gains with exchange costs, and adapts to environmental changes.

Contribution

It models physical layer security cooperation as a non-transferable utility coalitional game and proposes a distributed algorithm for coalition formation in decentralized networks.

Findings

Secrecy capacity improves by up to 25.32% with cooperation.

The algorithm enables autonomous coalition formation and network self-organization.

Coalitional structures adapt effectively to mobility and environmental changes.

Abstract

Cooperation between wireless network nodes is a promising technique for improving the physical layer security of wireless transmission, in terms of secrecy capacity, in the presence of multiple eavesdroppers. While existing physical layer security literature answered the question "what are the link-level secrecy capacity gains from cooperation?", this paper attempts to answer the question of "how to achieve those gains in a practical decentralized wireless network and in the presence of a secrecy capacity cost for information exchange?". For this purpose, we model the physical layer security cooperation problem as a coalitional game with non-transferable utility and propose a distributed algorithm for coalition formation. Through the proposed algorithm, the wireless users can autonomously cooperate and self-organize into disjoint independent coalitions, while maximizing their secrecy capacity taking into account the security costs during information exchange. We analyze the resulting coalitional structures, discuss their properties, and study how the users can self-adapt the network topology to environmental changes such as mobility. Simulation results show that the proposed algorithm allows the users to cooperate and self-organize while improving the average secrecy capacity per user up to 25.32% relative to the non-cooperative case.