Pulsed OFDM modulation for ultra wideband communications
We describe a new orthogonal frequency division multiplexing (OFDM) scheme, named pulsed-OFDM, for ultra wideband (UWB) communications. Pulsed-OFDM modulation uses pulsed sinusoids instead of continuous sinusoids to send information in parallel over different sub-carriers. Pulsating OFDM symbols spreads the spectrum of the modulated signals in the frequency domain leading to a spreading gain equal to the inverse of the duty cycle of the pulsed sub-carriers. The spreading gain provided by this system leads to an enhanced performance in multipath fading environments. We also show that at the receiver part of the multipath diversity can be exploited by pulsed-OFDM system leading to a low complexity and low power consumption transceiver structure. Easy implementation and frequency spreading of pulsed-OFDM modulation make it a proper modulation for UWB communications where the ratio of bandwidth to the data rate is large but power spectral density is limited. We design a low complexity and low power consumption pulsed-OFDM system for the IEEE 802.15.3a wireless personal area networks and compare it with the normal OFDM system has been proposed for this standard. We also provide realistic simulation results for the measured indoor propagation channels provided by the IEEE 802.15.3a standard to demonstrate the advantages of the pulsed OFDM modulation for UWB communications.