Performance of cosine series based offset quadrature binary modulation systems

The authors evaluate the performance of partial response signaling quadrature modulation techniques based on the cosine series functions design approach. The baseband quadrature modulation symbol is allowed to spill outside the interval [-T,T] to the interval [-2T,2T]. Spectral efficiency, envelope uniformity, intersymbol interference, and probability of error are the performance parameters of interest. Spectral efficiency and probability of error under hard limiting channel conditions are also considered. The performance is compared to that of quasi-bandlimited (QBL) symbol shaping and quadrature overlapped raised cosine modulation. It is shown that cosine series window functions used as baseband symbol shapes for quadrature binary modulation signals provide excellent spectral confinement, good envelope uniformity, and negligible transmission efficiency degradation. The simple modulator implementation makes the odd series n=3 QBL implementation a very attractive quadrature binary modulation choice