Energy-Efficient Power Allocation Strategy in Cognitive Relay Networks

Cognitive radio and cooperative technique are two essential techniques for the future generation green communication paradigm owing to its inherent advantages of adaptability and cognition. Typically, previous studies on power allocation in the cognitive relay networks often concentrate on two goals independently: the first goal is to minimize the transmit power to reduce energy consumption, as depicted in strategy 1, the second goal is to maximize the transmit rate, as depicted in strategy 2. In this paper we shift our focus to energy-efficient-oriented design, that is, green power allocation between source and relay. Therefore, we present a novel power allocation strategy considering the two goals jointly, as depicted in strategy 3, and compare the proposed strategy with two previous strategies. Specifically, because the strategy 3 is nonlinear we use the Lagrange dual method to solve it effectively. Finally, the numerical results are presented to validate our theoretical results through theory simulation and Monte Carlo simulation. Numerical performance results show that the proposed strategy works better than that of the two previous strategies from the viewpoints of energy-efficient.