The OFDM Physical Layer Technology's Algorithm Research And Implementation That Is Base On The IEEE 802.16e Standard

In the IEEE 802.16e communication standard, the physical layer uses the multi-carrier digital modulation. That is OFDM (orthogonal frequency division multiplexing) technology. OFDM is a multi-carrier high-speed transmission technology. It has high spectrum efficiency; resistance to inter symbol interference; what's more, this technology can against the multi-path fading. And the OFDM have other advantages. So this technology is very useful in the new generation of communications. But as the coin has the other side, OFDM technology has this characteristic; the multi-carrier transmission is very sensitive to the error of synchronization. Symbol timing offset and carrier frequency deviation would destroy the orthogonal among sub carriers, thus the introduction of inter carriers interrupt and inter symbol interference. This can reduce the overall system performance. Therefore, a good performance synchronization algorithm for OFDM system is very important. And in order to avoid inter-carrier interference and inter-symbol interference, the technical difficulty is in the OFDM communication system the demodulation side must be precisely synchronized. Therefore, the system must have a macro understanding and grasp of the entire communication system effectiveness and reliability of measurement, and then to be specific to the hardware debugging.First of all, using the MATLAB, the paper do an accurate simulation in the basis of the entire physical layer of communication system, during the simulation, a scheme and the algorithm improved for further verification. Then come to improve the communication system reliability. The main difficulty lies in the work of precise synchronization at the demodulation side. Include: frame synchronization, symbol synchronization, sampling synchronization. At the side of demodulation, use the best receiver to extract useful signal is proposed a new method in this paper.And then base on the TI cooperation's DM642 chip hardware and software development environment Code Composer Studio, use AIC23 for input and output data transmission unit to complete the communication system Baseband modulation function.Paper under the base-band communication system and structure of the mathematical model, which is overall proposed OFDM base-band system design and hardware modules were serious analysis of the circuit. The paper constructs the OFDM base-band hardware platform. Finally in the software environment CCS to achieve the various part of the software's modular programming.After testing, the paper completed OFDM base-band communication system design. A new improved demodulation scheme was used to improve the reliability of the system of transmission. In this communication system we have the effective synchronization, and have a small error rate. And part of the module in the hardware circuit has been verified.