Joint Optimization Of Energy Efficiency And Spectral Efficiency In TD-LTE-A Downlink

There has been an explosion of the smart mobile phone users and increasing damand for data traffic since 21 st century, which causes the research on mobile communications is greatly accelerated. Since the 3G standard was proposed by 3GPP, the wireless communications has entered in to the new era of data trffic instead of that of the voice and text. Origing from the China’s unique TD-SCDMA, TD-LTE-A is going to play an important role in the future evolution of LTE-A due to its unique duplex mode. How to improve the experience of the data traffic service will be the emphasis in the future B4 G and 5G research. In order to realize it, MIMO technology, which was first introduced in 3G standard, will go on to play a key role.At the same time, the rapidly developing communications in the new time are facing new challenges. Resource and environmental problems have been more serious day by day, the power consumption of industries includin g communication industries, has attracted attention and has been a new hotspot. The Green Radio emerged on such background. Improving the system power consumption and increasing the energy efficiency have gradually been the important research interests besides increasing spectral efficiency.First, the dissertation gives a briefu introduction to the TD-LTE-A system, retrospects its history and introduces related technology. Then the dissertation introruces the TD-LTE-A downlink model. Algorithms for resource allocation and power allocation are also introduced.Next, the dissertation investigates the energy efficiency in Green Radio. The expression of energy efficiency is given. Based on this expression, the energy effiecncy based resource allocation and power allocation algorithms are investigated. During the process, the user requirements and fairness are added as constraints, which makes the energy efficiency not the only target of the formulation. The simulation results show that the proposed algorithms improve the energy efficiency and fairness in the system.Finaly, the joint optimization of spectral efficiency and energy efficiency is investigated. In the first place, the closed form of the relation between spectral efficiency and energy efficiency and related analyses is given. Then we formulate the problem model, which takes spectral efficiency as a limiataion into consideration. To find the solution, the linear precoding is adopted to simplify the SINR expression. Besides, we introduce water-filling algorithm to convert the problem to a quasi-concave problem. The simulations at last demonstrate that the proposed algorithm shows a better comprehensive performance, which can realizes t he joint optimization of spectral efficiency and energy efficiency.