Obss Interference Management Scheme In The Next Generation WLAN

WLAN has gradually become an important way to access the Internet for its high speed,low cost,and ease of deployment.With the development of wireless communication techniques,a number of enhancement has been introduced to increase the system transmission rate,but few changes in MAC,which uses the DCF to contend the medium.In the practical WLAN system,its density is rapidly increasing to meet the increasing demand for broadband network transmission.In dense WLAN,DCF would increase the probability of access collision,system interference,and degrade transmission efficiency.Nodes in the OBSS area can receive the signals from multiple BSSs.It is difficult for OBSS users to contend with the medium,and successfully receive packets due to the interference from neighboring BSSs.The next-generation WLAN aims at improving the service quality of OBSS users and system performance in a variety of dense deployments.We first introduced related techniques in the WLAN system.The centralized management architecture is generally used in the large-scale dense WLAN network.An AC manages the network and adjusts configuration of BSSs.Next-generation WLAN is going to apply OFDMA to reduce contention collision in BSS,and DSC to enhance the access of OBSS users.NS3 is an approved network simulation platform in the scientific research.It implements the real protocol and can accurately evaluate the WIFI system techniques.This thesis focuses on the interference management technology of OBSS in the dense deployment of next-generation WLAN.We study the interference of users at different locations in a dense WLAN deployment.Based on the centralized architecture and OFDMA,a scheme for applying fractional frequency reuse in WLAN systems is introduced to mitigate OBSS interference.Orthogonal resource is allocated among interfering BSSs for OBSS users,while BSS-center users can use the same frequency.In the proposed scheme,STAs report the received signal strength of Beacon to its serving AP.The AP divides STAs into BSS center users and OBSS users.AP identifies the interfering AP based on the Beacon received signal strength.Then,AP cooperates with the AC to allocate the frequency resource.In the NS3,the initial work has implement OFDMA transmission.Based on the simulator,we implement nearly all the function of the resource allocation scheme,the procedure of Beacon monitoring and the channel switch operation.With the system examination,we confirm the simulation system correctly evaluate the proposed scheme.Finally,we build a variety of OBSS scenarios on the developed simulation platform to verify the performance of the proposed scheme.The results show that the scheme can improve the system throughput by more than 40%.The SINR of the OBSS users can be enhanced by more than 10 d B,and BSS center users also have slight enhancements.With fractional frequency reuse allocation scheme,all of the BSS has growth in throughput,and Qo S of OBSS users could be guaranteed.