Research On Interference Coordination In Densely Deployed Wi-Fi Scenarios

With the rapid development of emerging industries such as Internet of things,smart home,cloud computing and artificial intelligence and the wide application of various intelligent terminal products,the user group and market demand of WLAN business are expanding rapidly.Faceing the continuous and rapid growth of wireless data traffic and a large number of mobile terminal devices,plenty of wireless access points(Access Point,AP)are deployed in crowded places such as shopping malls,hotels,stations,campuses to achieve comprehensive network coverage and improve network capacity.However,the wireless spectrum resources are limited,and the dense deployment of Wi-Fi network will inevitably result in a large number of APs working in the same channel.When the coverage of AP overlaps,the co-channel interference between adjacent AP will greatly deteriorate the performance of edge users and even the whole network.Therefore,in order to improve network throughput and users’ online experience,it is increasingly important to seek an effective interference coordination scheme in densely deployed Wi-Fi networks.Considering the characteristics of multi-AP cooperative systems,this thesis studies the interference problem in densely deployment scenarios.The specific work is as follows.Firstly,this thesis analyzes the interference suffered by users under concurrent APs on the same frequency channel,and presents an interference coordination scheme based on the idea of collaborative scheduling and frequency reuse.By designing user scheduling algorithm,user grouping algorithm and RU(Resource Unit)allocation algorithm,the master AP can assign the same RU to the users with less interference,and assign orthogonal RU to the users with greater interference,so as to reduce the interference and improve spectral utilization.The simulation results show that the scheme proposed in this thesis can reduce the interference suffered by users of the Overlap Basic Service Set(OBSS)effectively and improve the throughput and spectral efficiency of the system while meeting the user’s delay limit.Then,the co-channel interference and overlay interference caused by unreasonable channel resource allocation are analyzed,and a joint optimization scheme of channel allocation and power control based on centralized control is designed.Based on the analysis of the interference,a resource optimization model with system throughput and energy efficiency maximization as optimization objectives,AP’s transmit power and user’s minimum SINR(Signal to Interference plus Noise Ratio)as constraints is established.Then this optimization problem is solved using the improved simulated annealing algorithm proposed in this thesis.The simulation results show that the joint optimization scheme proposed in this thesis can significantly reduce the co-frequency or overlapping frequency interference between APs,and greatly improve the throughput and energy efficiency of the system under the condition of ensuring the user’s minimum transmission rate requirement.