Multilevel PRS/QPRS Above the Nyquist Rate

An improved efficiency partial-response signaling (PRS) and quadrature partial-response signaling (QPRS) data filtering strategy, which enables a higher transmission rate (more symbols/s/Hz) than feasible with conventional PRS and QPRS systems, is introduced. With the use of our technique, a smaller number of signal levels (states) can be chosen for specified spectrally efficient applications; thus, an increase in S/N immunity is obtained with a lower cost and simpler hardware implementation.