Research On Mac Convergence Sublayer Of Wimax System

Wireless communications technology progress greatly promotes the development of wireless network, WiMAX broadband wireless access technology provides users with broadband access and multimedia services, which solves the last mile problem and is received widespread access. This thesis topic is from the Ministry of Science and Technology's international technology cooperation project - WiMAX Broadband Wireless Access Device R&D. The goal of this project is to put forward a simple and effective method to realize the protocol function. Research on MAC Convergence sublayer is my main job in this project.Main contents and results are as following, firstly, research on IEEE 802.16 protocol architecture, the convergence sublayer is the research focal point. Secondly, the convergence sublayer finishes the classification function, in connection with the fast classification problem, we propose a packet convergence sublayer classification algorithm- No conflict hash IP address block XOR search algorithm, which can satisfy the classification time performance and memory usage request of service. Thirdly, based on further research on the Payload Header Suppression (PHS) mechanism in IEEE 802.16-2004 and Robust Header Compression (ROHC) mechanism introduced in IEEE 802.16-2005, we propose a way to implement the PHS, which suppresses the RTP/UDP/IPv4 header to 20bytes.On account of the ROHC mechanism in WiMAX, we consider the wireless channel and put forward an adaptively compression method, which can compress the RTP/UDP/IPv4 header below 4bytes. The simulation results show ROHC is better than PHS on compression ratio and robustness, but more complex than PHS on realization. Fourthly, in order to save the wireless link resources, through the connection identifier field analysis in MAC PDU header, we put forward to compress this field self-adaptively according to wireless channel environment. The simulation result shows the compression possibility of this field. Finally, according to IEEE 802.16 protocol architecture and convergence sublayer function, we divide the function into modules and design them. On the MB87M3550 hardware platform introduced by the research institute, according to the proposed classification algorithm and PHS realization method, we develop and test each function module in Tornado2.2 environment. The test result is analyzed, which has the great significance for the project development.