A carrierless UWB/OFDM system

A carrierless UWB/OFDM system with pulse-based modulations (CL-UWB/OFDM) and its corresponding signal processing algorithms are presented in this paper. Compared with the traditional OFDM system, the CL-UWB/OFDM approach has several distinct characteristics. Firstly, the time-domain signals generated by IDFT are real rather than complex value due to the conjugate symmetry relationship of the frequency-domain signals. Secondly, a train of extremely short pulses instead of a sinusoidal carrier is employed to convey information. Thirdly, the received signals are orderly sampled through multiple parallel branches by exploiting the feature that the pulse repetition period is much larger than the duration of each pulse. Finally, the signals of each branch are independent of that of the other branches. Hence, these branches resemble the multiple fading-independent antennas in classical narrow-band systems. Due to the above properties, the CL-UWB/OFDM system has not only all virtues of the traditional OFDM system, such as resistance to multipath interference and narrow-band interference, but also other advantages, for instance, excellent immunity to fading and frequency offset, simpler transceiver, and low power spectral density.