Connection Probability And Energy Efficiency Analysis For LTE/Wi-Fi Dual-Mode Uplink Transmission

With the rapid growth of the number of mobile communication devices and the continuous improvement of service quality requirements,wireless communication networks need more spectrum resources to meet the growing access needs,and need to consume more energy to serve user equipments(UEs).The deployment of LTE communication on the unlicensed spectrum,i.e.,LTE-Unlicensed(LTE-U)communication,are able to solve the lack of spectrum,but it will also interfere with the Wi-Fi communication that has been authorized to work on the unlicensed spectrum.In order to provide high-quality and seamless communication services for LTE/Wi-Fi coexisting network,this paper utilizes stochastic geometry theory to model LTE/Wi-Fi coexisting heterogeneous network,and studies the interference distribution function,the successful connection probability and the effective energy efficiency of the network.For the access mechanism of LTE/Wi-Fi coexisting network,this paper assumes that UEs first compete to connect Wi-Fi networks by using carrier sense multiple access with collision avoidance(CSMA/CA)scheme.If unsuccessful,they then attempt cellular communication as cellular UEs(CUEs).Considering that Wi-Fi access point(WAP)in Wi-Fi network will be interfered by other Wi-Fi user equipments(WUEs),we derive the distribution function of total interference and its upper as well as lower bounds by the guard zone of interference.Because the successful connection probability determines whether UEs can access the network,based on the interference distribution function,we adopt CSMA/CA scheme and truncation outage probability of cellular communication to further derive the successful connection probability of Wi-Fi communication and cellular communication respectively.The simulation results show that the successful connection probability of Wi-Fi communication is affected by both received signal threshold and the energy detection threshold of WAPs.Finally,in order to enhance the energy efficiency of the UEs,this paper evaluates the energy efficiency of the uplink in LTE/Wi-Fi coexisting network,and obtains the closed-form expressions of effective energy efficiency.Compared with cellular communication,we observe that the average energy efficiency of Wi-Fi communication is independent of UEs' density and tends to saturate under the condition of larger received signal threshold,which shows that Wi-Fi communication has the potential to boost energy efficiency of system.The above researches are also of great significance to the practical deployment of cellular network.