Coexistence Mechanisms for LTE and Wi-Fi Networks over Unlicensed Frequency Bands

摘要

Recently, mobile data traffic has rapidly grown which results in many challenges especially in the radio spectrum needs. Thus, operating Long Term Evolution (LTE) in unlicensed bands is becoming an attractive area of research. In particular, the idea is to utulise the unlicensed spectrum by deploying other technologies over these unlicensed bands to coexist with Wi-Fi, radar, and Bluetooth. On the other hand, this coexistence between LTE and Wi-Fi technologies faces many limitations and challenges over these bands. In this context, this paper presents a coexistence analysis between LTE and Wi-Fi over the unlicensed 5 GHz band. The coexistence mechanism is studied by deploying different scenarios of LTE. The first scenario is by using LTE-Unlicensed duty-cycling (LTE-U), while the second one is by using LTE Licensed-Assisted Access (LTE-LAA). In particular, simulation results using NS-3 simulator for the throughput and latency for different coexistence deployments are provided. The simulation results show that the coexistence mechanism between LTE-LAA and Wi-Fi in the 5 GHz band outperforms that of LTE-U with Wi-Fi. Furthermore, the results show that the design of the Listen Before Talk (LBT) algorithm in LTE-LAA plays an important role in the coexistence mechanism. On the other hand, the impact of changing some parameters on LTE and Wi-Fi performances are studied. In particular, the results show that the performance is not affected by changing many parameters of LTE and Wi-Fi and LBT algorithm needs some modifications to deploy a fair coexistence mechanism.