arXiv subjects

Dhammika Jayalath

Publications and source records attributed to Dhammika Jayalath.

7 recordsLinked to original sources

arXiv2025

Efficient Localization of Directional Emitters via Joint Beampattern Estimation

The localization of directional RF emitters presents significant challenges for electronic warfare applications. Traditional localization methods, designed for omnidirectional emitters, experience degraded performance when applied to directional sources due to pronounced received signal strength (RSS) modulations introduced by directive beampatterns. This paper presents a robust direct position determination (DPD) approach that jointly estimates emitter position and beampattern parameters by incorporating RSS modulation from both path attenuation and directional gain alongside angle of arrival (AOA) and time difference of arrival (TDOA) information. To address the computational challenge of joint optimization over position and beampattern parameters, we develop an alternating maximization algorithm that decomposes the four-dimensional search into efficient iterative two-dimensional optimizations using a generalized beampattern model. Cramer-Rao Lower Bound (CRLB) analysis establishes theoretical performance limits, and numerical simulations demonstrate substantial improvements over conventional methods. At -10 dB SNR, the proposed approach achieves 49% to 61% error reduction compared to AOA-TDOA baselines, with performance approaching the CRLB above -10 dB. The algorithm converges rapidly, requiring 3 to 4 iterations on average, and exhibits robustness to beampattern model mismatch. A contrast-expanded half-power uncertainty metric is introduced to quantify localization confidence, revealing that the proposed method produces concentrated unimodal likelihood surfaces while conventional approaches generate spurious peaks. Sensitivity analysis demonstrates that optimal performance occurs when receivers are positioned at beampattern main lobe edges where RSS gradients are maximized.

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arXiv2024

Robustness and Security Enhancement of Radio Frequency Fingerprint Identification in Time-Varying Channels

Radio frequency fingerprint identification (RFFI) is becoming increasingly popular, especially in applications with constrained power, such as the Internet of Things (IoT). Due to subtle manufacturing variations, wireless devices have unique radio frequency fingerprints (RFFs). These RFFs can be used with pattern recognition algorithms to classify wireless devices. However, Implementing reliable RFFI in time-varying channels is challenging because RFFs are often distorted by channel effects, reducing the classification accuracy. This paper introduces a new channel-robust RFF, and leverages transfer learning to enhance RFFI in the time-varying channels. Experimental results show that the proposed RFFI system achieved an average classification accuracy improvement of 33.3 % in indoor environments and 34.5 % in outdoor environments. This paper also analyzes the security of the proposed RFFI system to address the security flaw in formalized impersonation attacks. Since RFF collection is being carried out in uncontrolled deployment environments, RFFI systems can be targeted with false RFFs sent by rogue devices. The resulting classifiers may classify the rogue devices as legitimate, effectively replacing their true identities. To defend against impersonation attacks, a novel keyless countermeasure is proposed, which exploits the intrinsic output of the softmax function after classifier training without sacrificing the lightweight nature of RFFI. Experimental results demonstrate an average increase of 0.3 in the area under the receiver operating characteristic curve (AUC), with a 40.0 % improvement in attack detection rate in indoor and outdoor environments.

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arXiv2023

On the Use of Power Amplifier Nonlinearity Quotient to Improve Radio Frequency Fingerprint Identification in Time-Varying Channels

Radio frequency fingerprint identification (RFFI) is a lightweight device authentication technique particularly desirable for power-constrained devices, e.g., the Internet of things (IoT) devices. Similar to biometric fingerprinting, RFFI exploits the intrinsic and unique hardware impairments resulting from manufacturing, such as power amplifier (PA) nonlinearity, to develop methods for device detection and classification. Due to the nature of wireless transmission, received signals are volatile when communication environments change. The resulting radio frequency fingerprints (RFFs) are distorted, leading to low device detection and classification accuracy. We propose a PA nonlinearity quotient and transfer learning classifier to design the environment-robust RFFI method. Firstly, we formalized and demonstrated that the PA nonlinearity quotient is independent of environmental changes. Secondly, we implemented transfer learning on a base classifier generated by data collected in an anechoic chamber, further improving device authentication and reducing disk and memory storage requirements. Extensive experiments, including indoor and outdoor settings, were carried out using LoRa devices. It is corroborated that the proposed PA nonlinearity quotient and transfer learning classifier significantly improved device detection and device classification accuracy. For example, the classification accuracy was improved by 33.3% and 34.5% under indoor and outdoor settings, respectively, compared to conventional deep learning and spectrogram-based classifiers.

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arXiv2022

Inter-Slice Mobility Management in 5G: Motivations, Standard Principles, Challenges and Research Directions

Mobility management in a sliced 5G network introduces new and complex challenges. In a network-sliced environment, user mobility has to be managed among not only different base stations or access technologies but also different slices. Managing user mobility among slices, or inter-slice mobility, motivates the need for new solutions. This article, presented as a tutorial, focuses on the problem of inter-slice mobility from the perspective of 3GPP standards for 5G. It provides a detailed overview of the relevant 3GPP standard principles. Accordingly, key technical gaps, challenges, and corresponding research directions are identified towards achieving seamless inter-slice mobility within the current 3GPP network slicing framework.

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arXiv2022

On Session Continuation among Slices for Inter-Slice Mobility Support in 3GPP Service-based Architecture

The 3GPP has provided its first standard specifications for network slicing in the recent Release 15. The fundamental principles are specified which constitute the standard network slicing framework. These specifications, however, lack the session continuation mechanisms among slices, which is a fundamental requirement to achieve inter-slice mobility. In this paper, we propose three solutions which enable session continuation among slices in the current 3GPP network slicing framework. These solutions are based on existing, well-established standard mechanisms. The first solution is based on the Return Routability/Binding Update (RR/BU) procedure of the popular Internet standard, Mobile IPv6 (MIPv6). The second solution is based on the 3GPP standard GPRS Tunnelling Protocol User Plane (GTPv1-U), which establishes a GTP tunnel between previous and new slice for session continuation. The third solution is a hybrid solution of both MIPv6-RR/BU and GTPv1-U protocols. We compare the performance of all these solutions through analytical modelling. Results show that the GTPv1-U based and the hybrid MIPv6/GTPv1-U solutions promise lower service disruption latency, however, incur higher resource utilization overhead compared to MIPv6-RR/BU and 3GPP standard PDU Session Establishment process.

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arXiv2022

ZSM-based Management and Orchestration of 3GPP Network Slicing: An Architectural Framework and Deployment Options

Driven by closed-loop automation, the Zero-Touch Network and Services Management (ZSM) framework offers invigorating features for the end-to-end management and orchestration of a sliced network. Although ZSM is considered a promising framework by 3GPP, there is a lack of concrete ZSM-based solutions for the 3GPP Network Slicing management. This article presents an architectural framework of a ZSM-based management system for 3GPP Network Slicing. The proposed framework employs recursive ZSM management domains to meet the specific management requirements of the standard 3GPP Network Slicing framework. Two deployment options are considered for the presented framework. The first option features the integration of the standard services of the 3GPP Management System within ZSM. The other one considers ZSM as a complementary system for the standard 3GPP Management System. From these deployment options, some key questions are identified on ZSM's interoperability with the existing 3GPP Network Slicing systems. Finally, for each option, the architectural and operational feasibility of the ZSM interoperation with 3GPP Network Slicing systems is shown through an example use case.

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arXiv2020

A Channel Perceiving Attack on Long-Range Key Generation and Its Countermeasure

The physical-layer key generation is a lightweight technique to generate secret keys from wireless channels for resource-constrained Internet of things (IoT) applications. The security of key generation relies on spatial decorrelation, which assumes that eavesdroppers observe uncorrelated channel measurements when they are located over a half-wavelength away from legitimate users. Unfortunately, there is no experimental validation for communications environments when there are large-scale and small-scale fading effects. Furthermore, while the current key generation work mainly focuses on short-range communications techniques such as WiFi and ZigBee, the exploration with long-range communications, e.g., LoRa, is rather limited. This paper presents a LoRa-based key generation testbed and reveals a new colluding-eavesdropping attack that perceives and utilizes large-scale fading effects in key generation channels, by using multiple eavesdroppers circularly around a legitimate user. We formalized the attack and validated it through extensive experiments conducted under both indoor and outdoor environments. It is corroborated that the attack reduces secret key capacity when large-scale fading is predominant. We further investigated potential defenses by proposing a conditional entropy and high-pass filter-based countermeasure to estimate and eliminate large-scale fading associated components. The experimental results demonstrated that the countermeasure can significantly improve the key generation's security when there are both varying large-scale and small-scale fading effects. The key bits generated by legitimate users have a low key disagreement rate (KDR) and validated by the NIST randomness tests. On the other hand, eavesdroppers' average KDR is increased to 0.49, which is no better than a random guess.

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