Reduction of Roughness in FIR-SR Filter to DESIGN the Higher Order QAM Communication System

This paper presents a method of designing hybrid analog/asymmetrical square-root (SR) FIR filters. In addition to the conventional frequency domain constraints, the proposed method considers time-domain constraints as well, including the inter-symbol interference (ISI) and the opening of the eye pattern at the receiver output. Newly conceived parameter, the “roughness” of the analog/FIR-SR filter impulse response, is taken into account. The error-performance of a system employing a matched SR filter pair, in the presence of receiver timing jitter, is more strongly related to how well the roughness parameter is minimized, than it is to the maximizing of the eye width caused by the Nyquist pulse. QAM conveys a higher information bit rate (bits per second) than a BPSK or QPSK signal. With the hybrid analog/SR FIR filter co-design, examples show that using the proposed method can result in a more robust ISI performance & reduction in PAPR in the presence of the receiver clock jitter.