Performance Analysis And Access Control Mechanism Design For LAA And Wi-Fi Coexistence In Unlicensed Band

With the rapid growth of wireless data,the shortage of spectrum resource and the massive user equipment access have become the main challenges of the 5G mobile communication.In order to provide users with better quality of service,macro cells,small cells and wireless local area networks will be integrated to work simultaneously in next generation networks.Licensed Assisted Access(LAA)technology,that can extend the LTE service to the unlicensed band(e.g.5GHz),is an effective solution to handle the problem of the shortage of spectrum resources that caused by the continuous increase of traffic.This thesis aims at analyzing the performance of the LAA and Wi-Fi coexistence in unlicensed band and designing the effective access control mechanism.First,two Markov models are established for LAA system and Wi-Fi system separately,based on which the relationship between different parameters and coexistence system performance such as throughput and delay are analyzed.Then,an adaptive access control mechanism is designed,by which the access parameters can be adjusted adaptively.Based on the simulation platform built using Matlab,it is shown that theoretical analyses match the simulation results well,the mechanism proposed in this thesis can guarantee the access fairness of the coexistence system and improve the overall system performance.In addition,in order to further improve the channel utilization,the performance of multichannel MAC in unlicensed band is analyzed through both theoretical derivation and system level simulation.It is proved that the multi-channel MAC outperforms the single-channel MAC.At last,a channel allocation algorithm is proposed which aims at guaranteeing the coexistence system fairness.Simulation results show that this allocation algorithm can guarantee the performance of Wi-Fi system and achieve better overall system performance.