Usman Ali

Recent studies have demonstrated the vulnerability of integrated sensing and communication (ISAC) systems to jamming and spoofing attacks, particularly in scenarios involving single radar systems. However, cooperation among networked sensors can enhance localization accuracy and mitigate such attacks by exploiting spatial consistency. This paper develops a theoretical framework based on the mismatched Cramér-Rao lower bound (MCRLB) to quantify the impact of spoofing on localization performance within cooperative ISAC networks. We examine how varying attack intensities and deployment configurations influence system resilience. Our analysis reveals that cooperative processing significantly reduces localization errors, highlighting the robustness of distributed sensing architectures against adversarial interference.

The performance of Space Division Multiple Access (SDMA) in Multiuser Multiple Input Single Output (MU-MISO) systems degrades significantly under imperfect Channel State Information at the Transmitter (CSIT). To address this, Rate-Splitting Multiple Access (RSMA) has been shown to outperform SDMA in scenarios where CSIT is imperfect, particularly in underloaded scenarios, where the number of potential users is lower than the number of antennas. This paper investigates the use of RSMA in a large-scale, overloaded system, where the number of users exceeds the number of antennas at the base station. We propose a novel approximation of the RSMA sum rate under limited feedback conditions and develop an optimal power allocation strategy that dynamically switches between RSMA and SDMA to maximize energy efficiency and system performance. Additionally, a robust Minimum Mean Square Error (MMSE) based precoding method is introduced to mitigate the effects of imperfect CSIT in private streams of RSMA. Numerical simulations validate our analytical derivations and show that RSMA offers superior performance over SDMA in large user regimes with low feedback loads, providing significant performance gains in realistic network conditions. These findings offer new insights into the design of energy-efficient and scalable downlink communication systems for future wireless networks.

Fifth Generation (5G) systems have been commercially available worldwide for at least a couple of years, with mid-band Non-Standalone (NSA) being the deployment mode preferred by Mobile Network Operators (MNOs). Empirical analyses have provided so far key insights on 5G NSA performance from different perspectives, but most of these works consider short time periods to drive conclusions. In this paper, we investigate the evolution of 5G NSA considering deployment, performance, and services, including positioning. We perform a large-scale measurement campaign in two phases (2021 and 2023), covering six MNOs in two European countries, Italy and Sweden. Our results show significant differences in network deployment and performance, with increasing network density and frequencies but, at times, decreasing downlink throughput performance. For the latter, we identify worse radio coverage and connectivity issues as root causes. By using a standardized methodology, we also evaluate the performance of new services such as real-time gaming and augmented/virtual reality, and reveal that stable 5G connectivity is key to meet their requirements. Similarly, we highlight the negative effects of roaming on performance. Finally, we evaluate 5G fingerprinting positioning systems and show that a higher accuracy is achievable in denser 5G deployments.

Fifth Generation (5G) networks have been operational worldwide for a couple of years. To reveal how the 5G system evolution (e.g., changes in network conditions, deployment, and configurations) affects user performance, empirical long-term analyses are required. This paper presents preliminary insights from our ongoing large-scale measurement study of the commercial 5G non-standalone (NSA) networks deployed in Rome, Italy. An initial comparison between the measurements in 2020-2021 vs. 2023 shows a decrease in throughput and latency performance, calling for deeper analyses toward understanding the root causes and deriving proper optimization solutions.

The successful rollout of fifth-generation (5G) networks requires a full understanding of the behavior of the propagation channel, taking into account the signal formats and the frequencies standardized by the Third Generation Partnership Project (3GPP). In the past, channel characterization for 5G has been addressed mainly based on the measurements performed on dedicated links in experimental setups. This paper presents a state-of-the-art contribution to the characterization of the outdoor-to-indoor radio channel in the 3.5 GHz band, based on experimental data for commercial, deployed 5G networks, collected during a large scale measurement campaign carried out in the city of Rome, Italy. The analysis presented in this work focuses on downlink, outdoor-to-indoor propagation for two operators adopting two different beamforming strategies, single wide-beam and multiple synchronization signal blocks (SSB) based beamforming; it is indeed the first contribution studying the impact of beamforming strategy in real 5G networks. The time and power-related channel characteristics, i.e., mean excess delay and Root Mean Square (RMS) delay spread, path loss, and K-factor are studied for the two operators in multiple measurement locations. The analysis of time and power-related parameters is supported and extended by a correlation analysis between each pair of parameters. The results show that beamforming strategy has a marked impact on propagation. A single wide-beam transmission leads, in fact, to lower RMS delay spread and lower mean excess delay compared to a multiple SSB-based transmission strategy. In addition, the single wide-beam transmission system is characterized by a smaller path loss and a higher K-factor, suggesting that the adoption of a multiple SSB-based transmission strategy may have a negative impact on downlink performance.

Understanding radio propagation characteristics and developing channel models is fundamental to building and operating wireless communication systems. Among others uses, channel characterization and modeling can be used for coverage and performance analysis and prediction. Within this context, this paper describes a comprehensive dataset of channel measurements performed to analyze outdoor-to-indoor propagation characteristics in the mid-band spectrum identified for the operation of 5th Generation (5G) cellular systems. Previous efforts to analyze outdoor-to-indoor propagation characteristics in this band were made by using measurements collected on dedicated, mostly single-link setups. Hence, measurements performed on deployed and operational 5G networks still lack in the literature. To fill this gap, this paper presents a dataset of measurements performed over commercial 5G networks. In particular, the dataset includes measurements of channel power delay profiles from two 5G networks in Band n78, i.e., 3.3–3.8 GHz. Such measurements were collected at multiple locations in a large office building in the city of Rome, Italy by using the Rohde & Schwarz (R&S) TSMA6 network scanner during several weeks in 2020 and 2021. A primary goal of the dataset is to provide an opportunity for researchers to investigate a large set of 5G channel measurements, aiming at analyzing the corresponding propagation characteristics toward the definition and refinement of empirical channel propagation models.

Tens of different IoT platforms are currently available on the market as a result of the high interest in IoT, characterized by very different characteristics in terms of utilization models, features and availability. This paper provides a review of existing platforms, both adopting a closed source and an open source access model, focusing on five evaluation criteria: communication protocols, data visualization, data processing, integration with external services and security. Afterward, the paper focuses on ten open source platforms, that are deemed more suitable for research and development activities in academia, and provides an evaluation of such platforms according to the five criteria previously defined, combined with two criteria specific to open source platforms: installation procedure and documentation. The evaluation indicates that the FIWARE platform is the best suited platform when taking into account the combination of the seven criteria; other platforms might, however, be preferred, depending on the context, thanks to specific features such as native support for a programming language, or ease and flexibility in the installation procedure.

Non‐orthogonal multiple access (NOMA) has been considered a key technology to address the increasing traffic demands for fifth‐generation (5G) cellular wireless communication networks and internet of things. The NOMA technique offers efficient bandwidth utilisation, low latency, and support for the massive connectivity of devices in 5G networks. In the conventional NOMA system, orthogonal frequency division multiplexing (OFDM) is used as a pulse‐shaping technique that causes high peak to average power ratio (PAPR) due to the superposition of signals of multiple users after passing through inverse fast Fourier transform and spectral inefficiency due to the cyclic prefix insertion. Therefore, an alternate methodology using wavelet OFDM is proposed in this research work, as a pulse‐shaping technique for NOMA‐based communication systems to improve spectral efficiency and system capacity The main contribution of this study is the analysis of the bit error rate (BER) performance and the effect of carrier frequency offset on system performance of wavelet NOMA (W‐NOMA) technique in 5G networks. The simulation results demonstrate that W‐NOMA outperforms the conventional NOMA with reference to PAPR and BER.

The non-orthogonal multiple access (NOMA) technique is a strong candidate for 5G cellular networks that enable greater multiuser capacity and user fairness through multiplexing in the power domain. The user data are pulse-shaped using the orthogonal frequency-division multiplexing (OFDM) technique based on the fast Fourier transform (FFT) for conventional NOMA. We propose a discrete wavelet transform-based pulse shaping technique for NOMA. We present a closed-form expression of the bit error rate (BER) for FFT-NOMA as well as wavelet-based NOMA (WNOMA) systems. The theoretical and simulation BER results show that WNOMA outperforms FFT-NOMA in additive white Gaussian noise.