Design And Implementation Of Accessing And Scheduling In MAC Layer Of Wlan Systems Based On CSMA/OFDMA Mechanism

The layer of MAC (Media Access Control) in wireless local area networks (WLAN) is put forward and designed to introduce such a accessing scheme with the aim of appropriately and efficiently allocating wireless resources for diverse stations or nodes dispersed in WLAN systems. With the surging deployment of wireless networks and in-depth research about the IEEE802.11wireless standard specifications, how to elevate the transmission rate of WLAN systems in an effective and efficient way has become the hotspot most researchers and professors have given much intensity to.One novel accessing mechanism called the two-dimensional CSMA/OFDMA hybrid accessing scheme has been notably and broadly acknowledged by academic researchers and business managers. On the basis of accessing wireless channels form both time and frequency domains, it is applicable and capable for these mobile terminals, applying the two-dimensional hybrid accessing scheme, to occupy the wireless resources to the fullest so as to effectively elevate the utilization rate of wireless resources as well as guarantee the probability of stations to access into the wireless channel and accomplish the procedure of data transmission, consequently optimizing these systematic comprehensive parameters including the probability of mobiles terminals’accessing wireless channels and the probability of successful transmission of data frames, the probability of collisions occurring in wireless channels as well as the overall throughput in MAC layer.On the basis of the ultimate version of project requirements and the novel draft of IEEE802.11ac standard specifications, the thesis has designed and composed the systematic implementation approaches, including the frame architecture of MAC packets, scheduling schemes for MAC-PHY interface and so on. Moreover, with the necessary foundation of the practical hardware devices and software environments, this thesis has discussed the procedure of the systematic development and realization for VHT-WLAN systems, subsequently achieving the objective that the system, in MAC layer, could achieve the systematic throughput more than1Gbps. Programming with C/C++on embedded planet (EP)8548A based on VxWorks with the RTOS circumstance for designing systematic implementing scheme. In-depth knowledge of TCP/IP protocols, capturing the systematic arguments and analyzing data in MAC layer using socket communications, using WPF for graphic dynamic display and renewal.This thesis is based on the national scientific and technological major projects-Key Technologies Research and Demonstration of VHT-WLAN (Very High Throughput Wireless Local Area Network) Systems with the national project number is2010ZX03005-001-03. And the project focus on the in-depth research of scheduling mechanisms which applies in the MAC layer of VHT-WLAN systems with the object of elevating the systematic throughput of MAC layer in this wireless networks. We design and program the scheme of MAC layer according to the research target and contents, and set up the scene of demonstrate in order to test and verify the key indicator, which make this thesis helpful to the research of very high throughput in the foreseeing future by relying on its greatly strengthened vitality.