| With the rapid development of wireless network technology and Internet, Wireless Lo-cal Area Network(WLAN) has been widely used because of its advantages in flexibility and convenience. Due to the development of IEEE802.11series standards and the related technologies of MAC layer and physical layer, WLAN technologies have been improved significantly in the areas of data transmission rate, bandwidth and security.The background of this thesis is a R&D project of a local enterprise. This project aims at designing a link level simulation platform based on Matlab to support WLAN technologies and features. The goal of the simulation platform is to simulate and verify the performance of physical layer and MAC layer access technologies of the IEEE802.11standard families, such as a/b/g/n/ac.The main work of this thesis encompasses following aspects. First,the access mecha-nism modules of DCF and EDCA in MAC layer are designed with Matlab to cooperate with the other physical layer modules of this platform. And then, a simulation link is established between MAC layer and physical layer, through which the throughput and collision prob-ability performances of DCF and EDCA mechanism are simulated and analyzed in different simulation scenarios, taking into account different number of STA, different minimum in-ter-frame spacing, the EDCA TXOP mechanism and different ideals and practical CCA probability of error. The resulted throughput performances of DCF and EDCA mechanism are compared with related literatures and theoretical results, showing that network perform-ance will be partially affected by the factors of the number of STA, the size of the minimum contention window, the application of TXOP mechanisms and the wrong judgment of CCA. Second, this thesis implements the simulation into the enhanced Long NAV and RIFS tech-nology proposed in802.11n. Under the foundation of DCF access mechanism module, the performance variation from SIFS in802.11a/b/g and RIFS in802.11n HT mode is contras-tively analyzed. The simulation results show that the performance of the network can be im-proved by around1.5%when using RIFS in HT mode under the same IBSS. In addition, in the case of applying EDCA access mode and each STA is configured with TXOP mechanism, the impact of using Long NAV and NAV are compared. Simulation results demonstrate that the conflict probability can be reduced and the throughput can be improved by Long NAV technology.The layout of this thesis is as follows, consisting of four chapters. Chapter1introduces the basic background of this thesis, the development of standards, current research status, the structure and major work of this thesis. Chapter2elaborates related technologies of MAC layer, including the theories of DCF and EDCA,802.1In MAC layer enhancement technol-ogy, DCF saturation throughput model. Chapter3and Chapter4discuss the realization of DCF and EDCA access mechanism by programming in detail respectively, as well as simu-lation results analysis under different scenarios. Finally, conclusion and prospect wrap up this thesis. |
