Distributed Bargaining Mechanisms for MIMO Dynamic Spectrum Access Systems

Dynamic spectrum access (DSA) and MIMO communications are among the most promising solutions to address the ever increasing wireless traffic demand. An integration that successfully embraces the two is far from trivial due to the dynamics of spectrum opportunities as well as the requirement to jointly optimize both spectrum allocation and spatial/antenna pattern in a distributed fashion. Regardless of spectrum dynamics and heterogeneity, existing literature on channel/power allocation in MIMO DSA systems is only applicable to centralized cases. Our objective here is to design distributed algorithms that jointly allocate opportunistic channels to various links and to simultaneously optimize the MIMO precoding matrices so as to achieve fairness or maximize network throughput. For self-interested DSA links, our distributed algorithm allows links to negotiate channel allocation based on Nash bargaining (NB) and configure the precoding matrices so that links' rate demands are guaranteed while the surplus resources (after meeting minimum rate demands) are fairly allocated. Next, we consider a network throughput maximization formulation (NET-MAX). Both the NB-based and NET-MAX problems are combinatorial with mixed variables. To tackle them, we first transform the original problems by incorporating the concept of timesharing. Using dual decomposition, we develop optimal distributed algorithms for timesharing case, which shed light on how to derive a distributed algorithm for the original problems. Our work fills a gap in the literature of channel allocation where a central controller is not available.