Digital RF Memory Jamming on OFDM SISO

Abstract

The purpose of this paper is to present the impact of intentional electronic countermeasures using a high-speed repeater jammer on a single input single output (SISO) OFDM communication system. The jammer is composed of high-speed ADCs, DACs and a high performance FPGA used to implement a digital radio frequency memory (DRFM) and other jammers. This jammer can repeat a modified version of the input signal by continuously changing the amplitude or delay. The DRFM method can then be used to generate advanced jamming techniques capable of replicating fast fading channels similar to multipath environments. It can also add a continuous wave, broadband or partial band noise. In this study, WiMAX signals are subjected to these different types of jamming. The resulting EVM measures are converted using simple probability equations relating EVM to BER. The signal's immunity to jamming can be extracted by measuring the needed Signal-to-Interference-Ratio (SIR) required to reach a predetermined BER threshold. The most effective jammers are then determined. Power-to-power comparisons show that the best intelligent jammer is only 2 dB less efficient compared to an ideal "genie-aided" noise jammer which knows which band to target.