[Back]

W. Kozek, A. F. Molisch:
"Nonorthogonal pulseshapes for multicarrier communications in doubly dispersive channels";
IEEE Journal on Selected Areas in Communications, JSAC-16 (1998), 1579 - 1589.

A new approach to multicarrier digital communication over time-varying, frequency selective fading channels is presented. We propose a transmission signal set whose basic structure is similar to standard OFDM-setups, i.e. a system of functions generated by time and frequency shifted versions of a pulse-like prototype function; this is known as a Weyl-Heisenberg (WH) system. However, unlike previous OFDM studies, which are restricted to the case of orthonormal pulses, we consider nonorthogonal pulses that are adapted to realistically available a priori knowledge on the channel. Perfect transmultiplexing in the case of an ideal channel is incorporated as a mathematical side-constraint. We derive the expected intersymbol/interchannel interference of such an NOFDM (non-orthogonal FDM) system under the assumption of a WSSUS (wide-sense stationary uncorrelated scattering) channel. Based on this result we compare OFDM and NOFDM schemes concerning robustness against delay/Doppler spread.