Design And Implementation Of Simulation Platform Of Next Generation WLAN's Key Technologies

In recent years, growth in IEEE 802.11 Wireless Local Area Network technology has drastically increased due to its ease of deployment, convenience and cost efficiency. More and more WLAN devices are being deployed in different environments, which result in multiple Overlapping Basic Service Set. The performance of current WLAN standard degrades seriously in dense deployment scenarios. Thus, the IEEE 802.11 ax task group was established to improve the performance of WLAN in dense deployments.With the further development of wireless network simulation platform, NS3 is being scientific researched as the mainstream of the simulation software WLAN. Compared with NS2, NS3 provides more real implementation of the WLAN protocol system and simulates more realistic WIFI network. In view of this, this paper deeply studies the system architecture of NS3, and the structure of NS3 and the key principle are introduced in detail. This paper sorts and explains the mechanism of NS3 data packet for transmission in the 802.11 agreement process, emphatically introduces the transmission details of data MAC layer and protocol layer in the following and the principle of calculation of packet's SINR.The CSMA/CA mechanism has inherent flaws, such as the hidden and exposed node problems. Both hidden and exposed nodes result in a decreased overall throughput, but the exposed node problem creates severe scalability problems, the total throughput of IEEE 802.11 network reaches a limit when the density of AP is increased. So, the DSC algorithm is proposed for IEEE 802.11 ax. By dynamically tuning the carrier sensing threshold, DSC algorithm can decrease the number of hidden nodes, balance the spatial reuse and the impact of collisions to get maximize throughput. This article describes an DSC simulation framework and build the DSC simulation platform based on NS3.19 simulator. Then, this article makes some research on the performance of DSC algorithm by using the DSC simulation platform. According to our test results, it is concluded that DSC algorithm can improve the throuthput of network in some secenarios. However, in some secenarios, it decreases the throuthput since the collisions. To solve this problem, this article proposes an enhancement for DSC algorithm.With the arising of more available bandwidth resource and new technology, the physical rate in WLAN has been significantly improved. On the other hand, the MAC layer of WLAN barely changed for the past 15 years. Current WLAN MAC protocol is a typical single user channel access and single user data transmission protocol, which is more applicable to low density WLAN deployment. In the dense deployment scenarios of IEEE 802.11 ax, the MAC efficiency of this single access single transmission protocol will deteriorate to almost 33%-40%. So, OFDMA technology is proposed for IEEE 802.11 ax to solve this problem. With OFDMA technology, the whole channel is divided into several sub-channels, and several subcarriers comprise one sub-channel. Thus, OFDMA enable multiuser channel access and multiuser data transmission since different nodes could use different sub-channels simultaneously, which can make remarkable improvement on MAC efficiency. This article describes an uplink OFDMA simulation framework and build the uplink OFDMA simulation platform based on NS3.19 simulator. Finally, this article makes some research on the performance of OFDMA technology by using the uplink OFDMA simulation platform.