Cross-Layer Energy Efficiency Modeling And Optimization For 5G Wireless Network

The development of wireless communication technologies has led to an explosive surge in mobile network users and mobile data traffic,and the energy consumption of the network has also increased.Green communications has thus attracted wide attentions in the industry and academia.At present,the International Telecommunication Union-Radio communications sector(ITU-R)expected that the network energy efficiency and the end-to-end latency in the Next Generation Mobile Communication Technology(5G)systems have a 100-fold increase and a 10-fold reduction,respectively.Reducing energy waste while ensuring quality-of-service(QoS)is an important problem of 5G network that must be addressed.Based on the above issue,energy efficiency modeling and optimization for guaranteeing ultra-low latency is studied in this paper.The main research contents and innovations are as follows.First of all,current energy efficiency studies consider that the transmitter circuitry will continue to work in most cases without considering the influence of the upper layer service on it,that is,ignoring the state that the circuitry has no data to be transmitted and thus overestimating the system energy consump-tion.In this paper,a new energy efficiency analysis model based on cross-layer design is proposed in this paper by introducing a two-mode circuitry for the transmitter and receiver.The two-mode circuit means that when the system has data to be transmitted,the circuitry is in transmission mode;on the contrary,the circuit is in idle mode.Compared with the single-mode circuitry,the sim-ulation results show that the analysis model in this paper can analyze system energy efficiency more accurately.Secondly,a power control scheme that gives priority to energy efficiency is proposed considering the end-to-end delay constraints based on the above new energy efficiency analysis model.There is a trade-off between end-to-end latency and energy efficiency,but existing studies have not given the specific mathematical relationship between the two.Based on the effective bandwidth theory and effective capacity theory,the exact mathematical relationship be?tween the above two is proved theoretically.The simulation results show that the power control scheme proposed by this paper can significantly improve en-ergy efficiency compared with other schemes.Finally,aiming at the traffic control problem with maximizing energy ef-ficiency under the constraints of end-to-end delay and transmit power,the re-lationship between the data arrival rate and the cross-layer energy efficiency is deduced.It is proved that the cross-layer energy efficiency is the quasi-concave function of the data arrival probability(or the average data length)through Cauchy inequality,that is,the maximum value of cross-layer energy efficiency is unique as the data arrival probability changes.The golden section search algorithm is used to search the optimal solution of cross-layer energy efficiency.The simulation results verify the accuracy of the analytical method.