FPGA implementation of Shaped Offset QPSK modulator

Abstract

This paper presents a novel architecture for the modulation scheme Shaped Offset QPSK (SOQPSK), which belongs to the class of Continuous Phase Modulations (CPMs). These waveforms have recently regained remarkable popularity, due to the increasing demand of highly energy and spectral efficient communication systems for deep-space, telemetry and Unmanned Aerial Vehicle (UAV) links, for example. To the best of the authors' knowledge, this is the first SOQPSK modulator architecture and implementation reported in literature. The modulation task itself is divided into a SOQPSK-specific precoding part, with minimal hardware complexity, as well as an optimized quadrature CPM modulator. With a proof-of-concept FPGA implementation, the feasibility of the proposed architecture is shown together with its close to optimal algorithmic performance.