We conduct an experimental investigation into the performance of several jamming waveforms against a common off-the-shelf (COTS) laptop. The performance metric is chosen to be bit error rate within the individual WLAN packets, as opposed to the usual system throughput. The considered jamming waveforms are noise-like waveforms generated with three methods: random QAM with OFDM symbols on varying selected subcarriers; tone signals on all the pilot subcarriers; and a triangular frequency sweep. Out of all these waveforms, those targeting the pilot subcarriers had improved effectiveness, with simple tones over the pilots giving the best results.

Unauthorized access to data has been a recognized risk of wireless systems for many decades. While security solutions in communications engineering have typically revolved around cryptography in the higher layers, a semi-recent development is the elevating interest into security in the physical layer, namely by utilizing jamming for protection. In this paper, we present an experimental study into a full-duplex jammer–receiver (i.e., “jamceiver”) that is able to simultaneously interfere with the same radio resources it is actively receiving from. The radio architecture is loosely based on frequency-modulated continuous-wave radars that are constant-envelope radio transceivers, which benefit from simple-but-efficient self-interference suppression in the analog baseband domain by using a passive highpass filter. Its limitation to constant-envelope transmission is not an issue for efficient jamming waveforms unlike it would be with conventional direct-conversion transceivers in full-duplex communications. To show the performance limits of a practical jamceiver, we present comprehensive measurement results from a laboratory environment as well as a jamming case study from an open park area with actual Wi-Fi signals. Especially, the experiments validate the feasibility of preventing eavesdropping with continuous low-power jamming in a large area around a full-duplex jamceiver that acts as an access point for simultaneously offering decent Wi-Fi service to an off-the-shelf laptop.

We study a multifunction transceiver whose operation is based on the frequency-modulated continuous-waveform concept to facilitate self-interference suppression. This causes the received signals after downconversion to move across the spectrum according to the frequency-modulation function. It is critical to accurately compensate these frequency deviations in order to process the received information. In this paper, we introduce a method for estimating these deviations in terms of the relative time delay between the signals used for downconversion and compensation. Estimation of this delay relies on statistics of the received signal, and only requires the aid of a generic auxiliary signal. Our method is supported by analytic derivation of the estimation formula, and is validated by means of simulation results.

This paper introduces and justifies a novel system concept that consists of full-duplex transceivers and uses a multifunction signal for simultaneous two-way communication, jamming and sensing tasks. The proposed device structure and wave-form enable simple-yet-effective interference suppression at the cost of being limited to constant-envelope transmission— this is a weakness only for the communication functionality that becomes limited to frequency-shift keying (FSK) while frequency-modulated continuous wave (FMCW) waveforms are effective for jamming and sensing purposes. We show how the transmission and reception as well as different interference and distortion compensation procedures are implemented in such multifunction transceivers. The system could be also applied for simultaneous spectrum monitoring with the above functions. Finally, we showcase the expected performance of such a system through numerical results.