Baseband Design For OFDM Mobile Communication System

Recently, with the development of economy, society, technology, and the improvement of living standards, the demand for mobile communication has increased rapidly. As agreed by many forums and literatures, wireless communication with high speed and high quality, anytime and anywhere, is the direction of the evolution in wireless communication field. The research of mobile system is very popular, and the deployment of mobile system is an evident tendency. However, the frequency spectrum is a very limited resource. It has become a severe obstacle to the development of mobile communication.Orthogonal Frequency Division Multiplexing (OFDM) technique, which divides the transmission channel into a number of orthogonal subchannels or subcarriers, has been proved to be an excellent approach to achieving high-speed data transmission while preserving high frequency spectrum efficiency. OFDM has been adopted by many wireless communication standards, such as IEEE802.11a Wireless LAN, IEEE 802.16e Wireless MAN, Digital Video Broadcast, etc. It has been widely accepted that OFDM system is one of the mainstreams in future mobile communication evolvement.This thesis focuses on the research and design of the OFDM baseband system. Firstly, relevant background of mobile communication is introduced. Then the wireless channel model, which is the foundation of every wireless system, is explained. Based on appropriate wireless channel model, the principle of OFDM is presented, and the block diagram of the whole OFDM baseband system is constructed. Next, some crucial processing techniques are discussed, including channel codec, synchronization, channel estimation, and adaptive modulation and power allocation. During the discussion, algorithms for these processing techniques are induced theoretically. After each part of the OFDM baseband system is studied, the whole system design, which is the major objective of this thesis, is completed and its performance is analyzed based on matlab simulation results. Finally, concluding remarks are given and future work is conceived.