Title :
Nonorthogonal pulseshapes for multicarrier communications in doubly dispersive channels
Author :
Kozek, Werner ; Molisch, Andreas F.
fDate :
10/1/1998 12:00:00 AM
Abstract :
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 orthogonal frequency division multiple access (OFDM)-setups, i.e., a system of functions generated by time and frequency-shifted versions of a pulse-like prototype function known as a Weyl-Heisenberg (WH) system. Unlike previous OFDM studies, however, which are restricted to the case of orthonormal pulses, we consider nonorthogonal pulses that are adapted to realistically available a priori knowledge of 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 a nonorthogonal FDM (NOFDM) system under the assumption of a wide-sense stationary uncorrelated scattering (WSSUS) channel. Based on this result, we compare OFDM and NOFDM schemes with regard to robustness against delay/Doppler spread
Keywords :
Doppler effect; OFDM modulation; adjacent channel interference; delays; digital radio; dispersive channels; electromagnetic wave scattering; fading channels; intersymbol interference; time-varying channels; transmultiplexing; AWGN channel; OFDM; WSSUS channel; Weyl-Heisenberg system; delay/Doppler spread; doubly dispersive channels; frequency selective fading channels; interchannel interference; intersymbol interference; multicarrier communications; multicarrier digital communication; nonorthogonal FDM; nonorthogonal pulses; nonorthogonal pulseshapes; orthogonal frequency division multiple access; pulse-like prototype function; time-varying channels; transmission signal set; transmultiplexing; wide-sense stationary uncorrelated scattering; wireless transmission; Digital communication; Fading; Frequency conversion; Interchannel interference; OFDM; Prototypes; Pulse generation; Robustness; Scattering; Signal generators;
Journal_Title :
Selected Areas in Communications, IEEE Journal on