Research On Energy Efficient Resource Allocation And D2D Technology In Distributed Antenna Systems

In recent years,with the increase of mobile communication equipment,the corresponding energy consumption is also rising.The green communication,aiming at reducing the energy consumption of communication,is becoming the development direction of the future mobile communication.At the same time,the next generation of mobile communications,5G,is also developing rapidly,and improving the energy efficiency of the communication system is an important performance indicator of 5G.Among the current research hotspots,the distributed antenna system is considered to be one of the main technologies to achieve "green communication",because of its unique antenna structure,which can effectively improve the spectrum efficiency,coverage and energy efficiency of the communication system.Besides,as one of the important technologies of 5G communication,D2 D communication also has significant effect on improving energy efficiency.Therefore,this paper will combine the above two technologies and study the optimization problem of energy efficiency of D2 D communication in distributed antenna system.Some energy-efficient adaptive transmission schemes are presented,including the power allocation scheme of distributed antenna system with continuous or discrete rate adaptive transmission,and the power allocation scheme of D2 D in distributed antenna system.The main work is shown as follows:1.The power allocation scheme based on continuous rate adaptive modulation is studied in distributed antenna system.Subject to the requirement of instantaneous target bit error rate,an energy efficiency optimization problem of continuous rate adaptive modulation system is established,where the maximum power constraint of remote antenna and the minimum rate constraint of users are both considered.The closed-form expression of optimal power allocation is obtained by using conventional optimization methods for solution,such as KKT condition,and an optimal power allocation algorithm based on continuous rate adaptive modulation for distributed antenna system is given.The simulation results show that the proposed power allocation algorithm can effectively improve the energy efficiency of the system and meet the demand of service quality.2.The power allocation scheme based on discrete rate adaptive modulation in distributed antenna system is studied.In view of the fact that the order of modulation is discrete in practical application,the switching threshold of each modulation mode is first given under the requirement of instantaneous target bit error rate.Based on this,the optimization problem of maximizing the energy efficiency of distributed antenna system under the discrete rate adaptive modulation is established.With the help of all kinds of optimization problem solving method,the closed-form expression of optimal power distribution is obtained,and the optimal power allocation algorithm is given based on exhaustive search.Besides,the closed-form expression of the outage probability of the system is also given,and its accuracy is verified by computer simulations.3.The power allocation scheme for D2 D communication in distributed antenna system is studied.A system model including D2 D communication is considered,where D2 D reuse the downlink channel resources of the distributed antenna system(i.e.,underlay inband D2D).According to the system model,the optimization problem of maximizing the D2 D energy efficiency is established,which considers the maximum power constraint of distributed antenna system and D2 D,as well as the minimum rate constraint of the cellular users.A closed form expression of optimal power allocation is obtained by solving this optimization problem.Based on exhaustive search and bisection method,two optimal power allocation algorithms are given.It is verified that these two algorithms can effectively improve the system energy efficiency.Besides,the complexity of the bisection method is lower than that of the exhaustive search.