Radio Lab

Measurement campaign for characterization of drone signals in Aveiro, Portugal

eguffens — Fri, 10 Oct 2025 14:18:08 +0000

Measurement campaign in Aveiro, Portugal, under the scope of NATO IST-SET 204, between October 6 and 10 2025. Several member states gathered in Aveiro for this measurement campaign with the goal of recording drone RF signals unde three scenarios: 1. rural, 2. semi-urban and 3. urban RF environment. We recorded drone RF signals in a military base (controlled environment), then in the campus of the University of Aveiro (semi-controlled environment with some transmissions in the background), and in an uncontrolled environment near the city center (drone RF signals with many transmissions in the same bands/RF interferences).

Researcher

Sanjoy Basak

Project

AIRFORC

An Enhanced End-to-End Framework for Drone RF Signal Classification

eguffens — Mon, 01 Sep 2025 14:14:00 +0000

Smart RF jamming relies on long-term spectrum prediction, which requires accurate, high-resolution RF detection and classification over extended observation periods. Detecting and classifying drone RF signals is particularly challenging due to short dwell times, high hopping rates, and narrow instantaneous bandwidths. This paper presents an enhanced end-to-end framework designed to meet these requirements for smart RF jamming, delivering high-resolution and precise detection and classification. We demonstrate that our Residual Neural Network (ResNet)-based You Only Look Once (YOLO) model effectively detects and extracts RF features from previously unseen drone signals with high accuracy, even when trained solely on a synthetic RF dataset. Furthermore, our ResNet classifier outperforms existing models, achieving 99.29% accuracy at 0 dB signal-to-noise ratio (SNR) for drone RF signals.

Link to the paper

Researcher

Sanjoy Basak

Project

AIRFORC

Heuristic method for relay node placement in heterogeneous wireless network

eguffens — Wed, 30 Apr 2025 14:00:41 +0000

Whether it is to initially deploy a network or to restore the connectivity in a partitioned one, the question of the optimal Relay Node (RN) placement arises. This problem is already challenging when considering a static homogeneous network. However, diversity in transmission parameters within the network can induce diversity in transmission ranges, imposing the consideration of heterogeneity in the network. Furthermore, if the nodes are moving, the RN placement scheme must manage a smooth repositioning of the RNs without any large jumps or major restructuring. This paper introduces an effective strategy for deploying the minimum number of RNs in order to restore the connectivity between the nodes of a partitioned heterogeneous network. Through the statistical analysis of results from numerous randomly generated scenarios, the proposed Barycenter-focused Relay nodes placement for Heterogeneous wireless Networks (BRHEN) algorithm is shown to be an improvement on other similar approaches in terms of the number of RNs and the latency. Additionally, BRHEN exhibits stability in the positions and number of RNs when small displacements are applied to the Initial Nodes (INs). This characteristic makes this method suitable for scenarios with moving INs.

Link to the paper

Researcher

Eliott Guffens

Project

DAP21-06

Follow up field measurements for UAV-aided Networks

eguffens — Thu, 10 Apr 2025 13:19:35 +0000

During these follow up field measurements, conducted in collaboration with the Belgian Defense’s 10th Group CIS, we were able to acquire positive data about the benefits of deploying UAVs as relay nodes in tactical communications. This campaign also allowed us to assess the enhancement capabilities of using UAVs to enhance ground networks. These tests are a follow up to the results presented in the paper linked below.

Link to paper

Researcher

Guffens Eliott

Project

DAP21-06

Wideband Cooperative Jamming with Band-Limited Known-Interference Cancellation

eguffens — Wed, 22 Jan 2025 13:30:53 +0000

Secure and reliable communications are vital to defense forces in achieving operational goals. Likewise, limiting the opponents’ capabilities to communicate further advances the host forces’ chances of operational success. In this work, we propose a method to fortify the host forces’ wireless communications against adversarial attacks while at the same time restricting the opponents’ capabilities to wirelessly communicate. That is, we propose a band-limited known-interference cancellation (KIC) method that enables the host forces to cover a large portion of the electromagnetic spectrum with wideband jamming, yet lets the host force communication nodes cancel that jamming signal upon reception even if the nodes only receive a narrowband portion of it. We study how the proposed KIC method works based on measurements with commercial off-the-shelf software-defined radios. The results demonstrate that the band-limited KIC method achieves performance that is comparable to non-band-limited methods and, in doing so, leads the way for practical applications of cooperative jamming in scenarios where narrowband communication links span over a wide bandwidth.

Link to the paper

Researcher

Vincent Le Nir

Project

LORACO

Field Tests for UAV-aided Networks

eguffens — Fri, 08 Nov 2024 14:07:30 +0000

Using UAVs as relay nodes offers some advantages in terms of deployment speed, 3D adaptability and line-of-sight probability. Field tests using Doodle Labs radios deployed on the ground and on drones were designed to assess the viability of such relays. This measurement campaign allowed us to gather relevant data regarding the selection of the antennas to be used and showed promising results for great distance relaying. It also supports the promising capabilities of the relay placement method developed from our algorithm described in paper found in the link below.

Link to paper

Researcher

Guffens Eliott

Project

DAP21-06

A Multispectral Camouflage Net Evaluation Capability

eguffens — Tue, 01 Oct 2024 14:08:00 +0000

The need for standardized guidelines and common evaluation techniques for assessing camouflage nets represents a challenge for the military operational community. This paper proposes a laboratory assessment methodology for the evaluation of camouflage nets. This method aims to be an accurate initial assessment before field tests, as the final stages for camouflage evaluation. Furthermore, it is more convenient to standardize laboratory indoor setups as the initial step because parameters can be controlled with precise equipment, eliminating any unexpected technical variables. Our approach combines radar testing in a semi-anechoic chamber and EO/IR (Electro-Optical/Infra-Red) assessment using an indoor laboratory setup. This method offers a more comprehensive and accurate evaluation compared to methods that focus on a single type of test. Following this procedure, we can assess the performance characteristics of camouflage nets by determining their behavior in all spectral domains associated with surveillance optical and radar equipment. For the EO/IR devices, we are interested in analyzing the nets in the 0.35 – 2.5 μm wavelength band, and both the Mid-Wave Infra-Red (MWIR) 3 – 5 μm and Long-Wave Infra-Red (LWIR) 8 – 12 μm thermal infrared transmission bands. For the radar systems, we focus on the X-band frequency in the range of 9 GHz to 11 GHz. The paper presents the results obtained by measuring three different multispectral camouflage net samples. It is shown that Samples Under Test (SUT) have relatively consistent average radar transmission attenuation with a small range of 2.22 dB. Furthermore, the average attenuation values vary between 3.3 dB and 14.71 dB when the camouflage net is rotated for further evaluation. Moreover, radar reflection results characterized by reflection coefficient values, standard deviation, mean, and Coefficient of Variation (CV), show that all samples, regardless of orientation, deviate from the consistent reference data of ten runs. In the thermal infrared domain, the nets are similar in terms of solar loading, showing a similar temperature increase of 8 ±1°C, but the transmission levels are different, between 11.7% and 21.8%. As for the reflectance measurements, the three SUT show different behaviors in terms of reflectance levels and contrast patterns, especially in the near and shortwave infrared bands of the EO domain.

Link to paper

Researcher

Radouane Karli

Project

DAP22-07

UAVs as Relay Nodes: Positioning Method for Heterogeneous Wireless Networks

eguffens — Wed, 05 Jun 2024 15:53:00 +0000

In scenarios where Relay Nodes (RNs) need to be deployed to restore the connectivity of a partitioned wireless network, a positioning method limiting the number of RNs required is necessary. Optimally, the method must take into account the differences of transmission ranges between the different nodes – or the heterogeneity in range of the network. In particular, Unmanned Aerial Vehicles (UAVs) are considered to be great candidates as RNs with their high mobility and ability to be quickly deployed. However, their radio parameters will be different from the Initial Nodes (INs) of the network and there will be a diversity in propagation channel. Plus, even the network might be heterogeneous. With a mobile initial network, the placement method also have to be stable in terms of RN positions and number with respect to IN displacements. This paper introduces an approach to modify an effective RN placement algorithm for homogeneous networks to create a new algorithm capable of managing heterogeneity in the networks. The new algorithm is the Barycenter-focused Relay Positioning for Heterogeneous Wireless Networks (BRHEN) algorithm. In addition to lower the number of RNs compared to the initial algorithm, it also enhances its stability with respect to small IN displacements.

Link to the paper

Researcher

Eliott Guffens

Project

DAP21-06

Distributed Cooperative Jamming with Multi-Reference Known-Interference Cancellation

eguffens — Wed, 05 Jun 2024 15:09:00 +0000

Secure and reliable tactical communications within allied defense forces across a battlefield are often fundamental for achieving the forces’ operational targets against an adversary. Likewise, limiting the adversary’s capability to communicate securely and reliably promotes the host forces’ chances for operational success. As such, armed conflicts typically involve an underlying battle in the electromagnetic (EM) spectrum to facilitate one’s own communications and limit the opposition’s. In this work, we propose the use of distributed cooperative jamming for augmenting tactical communications and gaining a technological advantage in that underlying battle. Specifically, we propose a multi-reference known-interference cancellation (KIC) method that allows the host force tactical communication nodes to cancel known interference (KI) from multiple cooperative jammers simultaneously. Relying on simulations, we then study how cooperative jamming affects the opposing forces’ capabilities to use the EM spectrum in a simplified battlefield. Results show that cooperative jamming gives an advantage to those controlling the jammers, as the opposition’s use of the EM spectrum is obstructed for both communications and signals intelligence.

Link to the paper

Researcher

Vincent Le Nir

Projects

DAP21-01, IST-175

Spectrum Prediction for Protocol-Aware RF Jamming

eguffens — Mon, 01 Apr 2024 13:26:00 +0000

Neutralizing a drone using a protocol-aware RF jammer requires precise knowledge of the occupied spectrum in the time and frequency domains. This paper aims to develop an automatic spectrum prediction framework utilizing the Convolutional Neural Network (CNN) and Long Short Term Memory (LSTM) models. We generate a synthetic dataset using the commonly used drone signal properties and parameters, and evaluate the prediction performance under several realistic scenarios. Our experiment shows that the CNN-LSTM model can accurately predict future time and frequency sequences by using the spectrogram matrix as the input. We obtained better prediction performance with lower computational costs with our framework compared to the existing frameworks. Furthermore, we show that the CNN-LSTM model can predict future time-frequency sequences of unseen hopping rates and patterns when using transfer learning. The performance validation is also performed using real drone RF signals. Furthermore, we present a two-stage spectrum prediction approach that achieves excellent performance by offering higher frequency resolutions while maintaining a lower computational cost.

Link to the paper

Researcher

Sanjoy Basak

Project

AIRFORC

Dynamic Spectrum Management and Routing Solutions for Multi-Radio Mobile Ad Hoc Networks

eguffens — Tue, 28 Nov 2023 15:11:00 +0000

The electromagnetic spectrum’s scarcity, the tactical edge’s dynamic nature, and the variety of tactical operations impose challenges to military cognitive radio networks. Multi-radio dynamic spectrum management (DSM) and routing promise to increase the spectral efficiency and robustness of tactical ad hoc networks by adding key control plane tools that adapt the network to the varying harsh tactical environments. This paper describes a novel concept where implicit spectrum sensing, a distributed DSM architecture with ontology-based spectrum access policies, modified routing and network time synchronization capabilities interplay to address those challenges. The simulation results verify the designed functionality in harsh electromagnetic environments in a multitude of scenario sizes, in terms of number of radio terminals and number of networks. In particular, the simulation of a large operational scenario shows solid scaling capabilities and that ongoing jamming in several networks is efficiently mitigated and low-loss performance are re-established.

Link to the paper

Researcher

Vincent Le Nir

Project

DAP21-01

Assessment of the Antenna Mounting Location on a Military Vehicle for Jamming Applications Based on Computational Electromagnetics

eguffens — Wed, 20 Sep 2023 13:31:00 +0000

The placement of an antenna on the roof of a military vehicle-mounted jamming system presents many challenges. For that, further approaches are needed to study the effectiveness of placing antennas on these vehicles. Besides, due to the cost, time, and technical difficulties in measuring the suitable antenna locations on large tactical vehicles, there is a demand for methods to compute the optimal position for antennas before installation and for jamming coverage of 360° around the vehicle. In this paper, we analyze a simulation model based on an UWB (Ultra-Wideband) discone antenna placed on the roof of a MPP (Multi-Purpose Protected) military vehicle. The proposed discone antenna shows good UWB characteristics, and operates in the frequency band from 0.81 GHz to 6 GHz for a VSWR below 2:1 over the whole bandwidth. It displays a good radiation pattern behavior with a good average radiation efficiency of around 71 % when mounted on a military vehicle. In addition, the radiation pattern was compared for the stand-alone antenna in free space taking as a reference and at four locations on the roof of the military vehicles, at five frequencies. The antenna at the back of the roof of the vehicle has the most optimal results, with adequate far-field behaviors for jamming applications. The results confirm the significant advantage of an UWB discone antenna that could be installed on a military vehicle-mounted jamming system platform as an alternative potential candidate to conventional antennas. ‘This paper was originally presented at the NATO Science and Technology Organization Symposium (ICMCIS) organized by the Information Systems Technology (IST) Panel, IST-200RSY – the ICMCIS, held in Skopje, North Macedonia, 16-17 May 2023’.

Link to the paper

Researchers

Radouane Karli

Mathias Beacquaert

Project

DAP22-07