An All-Digital Wideband OFDM-based Frequency-hopping System using RF Sampling Data Converters

Traditionally, a wideband frequency hopping spread-spectrum (FHSS) system involves the use of analog mixers and oscillators for hopping the baseband signal to different higher frequencies. Such typical heterodyne receiver architectures have higher cost and form factors. Motivated by the recent development of direct radio-frequency (RF) data converters, this paper proposes an all-digital wideband orthogonal frequency division multiplexing (OFDM) based FHSS system using an RF direct sampling receiver architecture. The frequency-hopping is done in a two-stage process, with one at the baseband and the other at the carrier frequency to make it robust from any malicious attacks in the form of eavesdropping and jamming. The all-digital process of RF signal generation and detection in the system is verified over-the-air by using the RF sampling data converters of the Xilinx Ultrascale ZCU111 RFSoC board and Qorvo RF front-end. Later, a simulated bit error rate (BER) analysis of the system under a slow-fading channel and pilot-based channel estimation is carried out, which shows comparable performance with that of an analog FHSS system at radio frequencies.