Multiband Orthogonal Frequency Division Multiplexing Based Ultra Wideband System

摘要

Multiband OFDM based Ultra Wideband (UWB) system combines OFDM modulation technique with a multi banding approach, which divides the spectrum into several sub-bands, whose bandwidth is approximately 500MHz. Three band multi band OFDM systems have been designed using a time frequency code of length 3. The important blocks in the transmitter side are QPSK modulator, IFFT, DAC, up converter and time frequency code generator to provide multiple access and frequency diversity. We model channel as a simple delay element. A basic receiver just follows the inverse of the transmission process so important blocks in the receiver side are down converter, ADC and FFT. OFDM based system is very sensitive to timing and frequency offsets, the received constellation is slightly different from transmitted constellation due to processing delay and additional delay introduced from the channel. This paper provides the analysis of impact of delay on OFDM based UWB system