Demonstration of GNU Radio High Data Rate QPSK Modem at 15.0 Mbps Real-Time with Multi-Core General Purpose Processor

Abstract

This paper presents a GNU Radio Modulator/Demodulator (Modem) design and an associated test activity that demonstrates a GNU Radio modem can operate at 15.0 Mbps Real-Time with Quadrature Phase Shift Keying (QPSK), with GNU Radio version 3.10, and with a multi-core (8-core) General Purpose Processor (GPP) inside a relatively low cost Personal Computer (PC). The Modem demodulator design achieves the high date rate with a single GNU Radio flowgraph and without a Field Programmable Gate Array (FPGA) or Graphics Processor Unit (GPU). Specifically, the Modem demodulator design achieves the high data rate by breaking the incoming I/Q sample stream from a LimeSDR-mini into three “chunk” streams. Each chunk stream then flows to a separate Symbol Synchronizer (symbol synchronization) and Costas Loop (carrier synchronization) chain and each chain uses a separate GPP core. The GNU Radio Modem demodulator then “stitches” the original transmitted single stream back together by only using the frame Acquisition Synchronization Marker (ASM) and the known frame length of each frame.