Research On Key-Technique In PHY Based On IEEE802.16d

OFDM (Orthogonal Frequency Division Multiplexing), also known as orthogonal frequency division multiplexing technology is introduced in the 20th century,the 1950 and 1960s.The technology has a great advantage in the noise and multi-path interference,particularly, it can effectively overcome the multi-path interference in the mobile channel environment.IEEE802.16d is devised to serve as the standard for fixed wireless broadband MAN access,incorporating many new technologies at physical and media access layer,having an advantage in system capacity and coverage range over wireless LAN system.IEEE 802.16d employs OFDM as mandatory modulation mechanism at physical layer.In this dissertation, we introduced the development, basic principles, advantages and disadvantages of OFDM. We also introduced IEEE802.16d Physical layer standard. This thesis aims to explore the algorithm, architecture and implementation of an ODFM baseband Processor targeted on its application in IEEE802.16d system.The main task is to complete the modeling process of the OFDM transmitter and receiver. In this dissertation, the Basic Principle and System Structure of OFDM and the physical layer standard of IEEE802.16d are introduced, and also how to design OFDM transmitter according the physical layer standard of IEEE802.16d and working principle and implementation method of main modules in the transmitter are discussed in detail. During the design of Receiver, the cause of Synchronous Error and the effect of Synchronous Error on OFDM system are simply analyzed first of all, in view of the characteristics of burst communication based on IEEE802.16d, proper synchronization scheme is designed. According to the characteristics of the preamble structure of the transmit signal and the guides in the standard, frame synchronization, frequency synchronization and symbol synchronization are implemented in time domain with the training sequence, while carrier phase tracking and channel estimation and equalization are implemented in frequency domain with the training sequence and pilots. This synchronization scheme has simple structure, less calculation amount and meets the synchronization requirements of burst communication well.