Research Of The OFDM Modulation And Its Application In WLAN

From wire communication to wireless communication, then to fiber communication, with the development of communication technology, there have more and more communication technique. However, to the essential of communication technology, those techniques are all change in transmission medium or channel. Recently, because of the development of DSP, IFFT/FFT, 46/128/256QAM using in high-speed modem, and gradual introduction of new coding technique, soft decision technique, channel self-adapting, Guard Interval, OFDM (Orthogonal Frequency Division Multiplexing) arouse more and more attention. As a technology of high-speed transmission, OFDM can resist ISI effectively.This paper is based on the concise and deep-going survey of OFDM, and finished the following three parts.In the first part, researches the theory of OFDM, and how to realize OFDM system by FFT/IFFT. Later, simulates the OFDM system by MATLAB software, researchs the effect about OFDM system by mapping, guard interval, sub-carrier and channel. Gets some important conclusions, these conclusions are very useful in the design of practical system.In the second part, introduces the theory of wireless LAN based on the OFDM, supplies the corresponding simulation analysis by SYSTEMVIEW software, compares two channel coding by simulatation, gives a advice to use convolution coding, and analyses its BER.In the third part, gives a new FFT algorithm for realization OFDM modulation in FPGA. This algorithm is based on the 16-FFT about square root decomposition, and using the phase revolution unit replaces multiplication, and uses the serial butterfly operation unit. At last, gives the correspond realization measure in FPGA.KEYWORDS: OFDM,MCM,WLAN,IFFT...