Optimal Power Allocation for CR MIMO Energy Harvesting Coexisting Systems

Cognitive radio (CR) can be combined with energy harvesting and multiple antenna mechanics to lift the spectrum efficiency and make use of green energy. The allocated power for the secondary user (SU), equipped with multiple antennas, needs to have peak power constraints to restrict the interference with the primary user (PU). On the other side, the energy harvesting property of the nodes leads to the causality feature when allocating the harvested energy. In this paper, we apply our recently proposed geometric water-filling with group upper bounded power constraints (GWFGUP) and recursion machinery to form the proposed algorithm for solving the target throughput maximization problem. This proposed CR multiple input multiple output energy harvesting power allocation algorithm (CRMPA) is precisely defined. It provides the exact optimal solution via efficient finite computation. Significant throughput gain of our proposed algorithm can be observed over the existing optimization methods, e.g., the well-known primal- dual interior point method (PD-IPM), although the used PD-IPM is based on our proposed equivalent real problem.