A Multi-Leader Multi-Follower Stackelberg Game for Dynamic Spectrum Sharing in a Blockchain Enabled Cell-Free Massive MIMO Scenario

Abstract

[eng] The stringent quality-of-service (QoS) requirements that are being considered for the sixth generation (6G) of mobile networks will necessarily imply the synergistic application of different mechanisms ranging from physical layer processing to radio resource management aspects. In particular, this work blends three complementary techniques that are bound to play a central role in the transition towards 6G. Firstly, cell-free massive MIMO (CF-mMIMO) is often heralded as a foundational physical layer technique that is able to address the demanding spectral efficiencies (SEs) planned for 6G. Secondly, dynamic spectrum sharing (DSS) has shown its potential to optimize the exploitation of the always-scarce radio spectrum. Finally, blockchain technology is used to make these bandwidth transactions fair and accountable. This work presents a general architecture where multiple sellers and buyers of spectrum can dynamically trade spectral resources, leveraging CF-mMIMO-based wireless networks and guided by Stackelberg game theory. Notably, all parameters, operations, and outcomes of this trade protocol are securely recorded on a blockchain using smarts contracts (SCs). Exhaustive numerical results are provided that showcase the effects different network parameters have on the network performance while also revealing the cost associated with blockchain processing when relying on several popular blockchain platforms.