Energy Efficiency and Spectral Efficiency Tradeoff in Cognitive Heterogeneous System with Economic Consideration

Rapid development of the wireless communication industry has led to a dramatic increase of energy consumption. Energy Efficiency (EE) for the wireless networks has received considerable attention. Unfortunately, the increasing EE performance often leads to decreasing Spectral Efficiency (SE) performance and vice verse. Hence, it is often urgent to build a tradeoff between EE and SE. In this paper, the tradeoff between EE and SE is considered under the smart grid and cognitive heterogeneous environment. The economic EE and SE are proposed based on the price factor of economics. Based on these definitions, the economic EE-SE relation is deduced, where the price factors can adjust the minimum economic EE. Then a new EE-SE tradeoff metric called the Economic Resource Efficiency (ERE) is built, which can be maximized by adjusting the weight factor and utilizing the fluctuation of the electricity price and the spectrum price. Furthermore, the optimization problem of ERE is presented, and the solution of ERE is proposed for the Orthogonal Frequency Division Multiplexing (OFDM) system. The simulation results validate that the proposed ERE metric is efficient to the tradeoff between EE and SE, and to utilize the energy and bandwidth resources.