An NS frequency-domain approach for continuous-time design of CAP/ICOM waveform

The carrierless amplitude and phase (CAP) waveforms belong to a class of intersymbol interference ( ISI)-free and cross-channel interference (CCI)-free orthogonally multiplexed (ICOM) waveforms, and are considered as several modulation techniques for high-speed digital subscriber loops. This paper contributes a new set of frequency-domain constraints which are necessary and sufficient (NS) for the most general m-dimensional CAP or ICOM transceiver structure to be free of ISI and CCI in the continuous-time domain. The minimum bandwidth required for the most general m-dimensional ICOM transceiver structure is also theoretically proven using the new constraints. A new set of continuous-time two-dimensional (2-D) ICOM pulses, designed using the new NS constraints, is also included to demonstrate the usefulness of the frequency-domain NS constraints. The new 2-D ICOM pulses lead to transceiver eye patterns that are larger than the conventional 2-D CAP eye patterns.