Energy-efficient Physical Layer Designs For Wireless Communication Systems

With the rapid development of wireless communication technology,users need more and more wireless service.That reflects growing wireless data rate requirements,and the wireless communication system faces challenge of both SE and EE.With the3 G and even 4G communication networks put into operation,the energy consumption of wireless communication will grow rapidly.As an important part of energy consumption of wireless communication system,reducing the transmit terminal energy consumption has a practical significance.Due to the probability and mobility of users' terminals,the size and weight of them are restricted.Besides the slow progress of battery material,it causes the “battery bottleneck” of users' terminals.Thus,improving the terminals' EE can also improve the effective communication time and prolong the batter life.This thesis investigates three different communication scenarios:orthogonal frequency division multiple access(OFDMA)system,wireless powered communication system,and green offloading based spectrum-power trading system.For the OFDMA scenario,an optimal and a suboptimal but low complexity methods are proposed to tackle the energy efficiency maximization problems with consideration of both transmitter and receiver.The conditional optimality of the proposed low complexity is also analyzed with rigorous proof.This method exploits the special structure of the energy efficiency maximization problem and provide new ideas for solving such a kind of problems.For the wireless powered communication scenario,wireless power transfer has been integrated with wireless information transmission.A general transmission and power model is established.We investigate the system energy efficiency maximization problem with and without the minimum system throughput.The optimal transmission strategies have been derived and various algorithms have also been proposed.For the green offloading scenario,a spectrum-power trading mechanism is proposed for two neighbour base stations.We also propose novel algorithms to demonstrate the effectiveness of this mechanism.In summary,this paper derives the energy efficiency upper bounds of many wireless communication scenarios and also proposes various novel algorithms for both conventional and the newly formulated optimization problems.It provides new ideas for future theoretical research on green communication and the results of this paper also shed lights on the energy-efficient designs of practical wireless communication systems.