Downlink Power Allocation of Satellite Underlay Cognitive Radio

摘要

In this paper,we consider power control problem for a secondary cognitive satellite network to reuse the underutilized spectrum which is licensed by an existing primary system.Secondary users can be allocated power provided that the interference caused by secondary system to any primary user is below a critical threshold.We focus on the downlink.We formulate the problem as a game theoretic problem with the participants in cognitive network as the players.We propose an optimal control scheme that can be accepted willingly by secondary users and can maximize the spectrum utilization for satellite communication.By calculating Nash Equilibrium iteratively and using payoff dominance selection,we address the optimal power allocation within the constraints including quality of service protection for all users and maximum transmission power of the onboard power amplifier.Simulation is preformed to study the performances of both networks and of each user.We find that throughput and spectrum efficiency is greatly increased by the proposed scheme compared with traditional satellite networks where fixed power is allocated to only primary users.Also,the complexity is analyzed.