Simulation Of Non-Orthogonal Frequency Division Multiplexing In WLAN Based On WiFi

The objective of the thesis is to investigate the applications of a new technology -NFDM (Non-Orthogonal Frequency-Division Multiplex) in wireless local area networks based on WiFi. NFDM is derived from NMT (Non-Orthogonal Modulation Technology)-a new modulation technology. NMT is not limited by the orthogonality among sub-carriers. Each NMT code constitutes of many delayed sub-waves which is different from traditional technology. The previous researches demonstrate that NMT can increase transmission rate and enlarge transmission distance. The main work of the thesis is to investigate the application possibility of NFDM in wireless local area networks through computer simulation. The thesis discusses the basic principle of NFDM and the specialties of WLAN channel, and makes reference to wireless indoor model in order to research the system function under the simulation platform of Matlab. The parameters of the system are determined in accordance with IEEE802.11a. The simulation works contain wave pre-processing, modulation, pilot signal and guide signal inserting, wireless channel, receiving filter, channel estimation and compensation, demodulation, and bit error rate calculating. The thesis also researches the improvement of system performance of NFDM after the introduction of wave pre-processing and channel estimation with inserting different pilot signals and comparisons between NFDM and OFDM are also made by simulation. As far as bandwidth efficiency is concerned, experimental results show that NFDM is superior to OFDM, and in the condition of high SNR the transmission rate of NFDM is higher than OFDM.