This paper proposes a comprehensive framework for optimizing the deployment of Unmanned Aerial Vehicles (UAVs) in a communication system, aiming to minimize the transmission power of UAVs while ensuring the required data rates for ground users. The proposed model accounts for both large- and small-scale fading effects. To accurately capture the characteristics of the wireless channel, the Rician Shadowed fading model is adopted, as it incorporates both line-of-sight (LoS) and nonline-of-sight (NLoS) components. A mathematical formulation of the problem is presented, and the impact of the Rician shadowed fading parameters, the severity of the fluctuations in the LoS component, and the ratio between the powers of the LoS and NLoS components is considered. The simulation results demonstrate that increasing the parameters improves channel conditions, thus reducing the transmission power required to meet the minimum data rate constraints. To address the UAV 3D placement problem, which results in a non-convex and analytically intractable optimization due to the nonlinearities introduced by the channel model. Therefore, we employ a heuristic algorithm, Particle Swarm Optimization Evolutionary (PSO-E).

The increasing demand for reliable, high-capacity communication during large-scale outdoor events poses significant challenges for traditional Terrestrial Networks (TNs), which often struggle to provide consistent coverage in high-density environments. This paper presents a novel Sixth Generation (6G) radio network planning framework that integrates Non-Terrestrial Networks (NTNs) with Reconfigurable Intelligent Surfaces (RISs) to deliver ubiquitous coverage and enhanced network capacity. Our framework overcomes the limitations of conventional deployable base stations by leveraging NTN architectures, including Low Earth Orbit (LEO) satellites—and passive RIS platforms seamlessly integrated with Beyond 5G (B5G) TNs. By incorporating advanced B5G technologies such as Massive Multiple-Input Multiple-Output (mMIMO) and beamforming, and by optimizing spectrum utilization across the C, S, and Ka bands, we implement a rigorous interference management strategy based on a dynamic SINR model. Comprehensive calculations and simulations validate the proposed framework, demonstrating significant improvements in connectivity, reliability, and cost-efficiency in crowded scenarios. This integration strategy represents a promising solution for meeting the evolving demands of future 6G networks.

This study presents a privacy-sensitive traffic signal control system based on Deep Q-Networks (DQN) aimed at reducing carbon emissions in urban dense scenarios by minimizing vehicle waiting time at road intersections. The system utilizes data from the city infrastructure (non-sensitive data) while addressing privacy concerns. We validate the model's effectiveness using a testing framework that includes various reward function models, training scenarios, and traffic conditions. Preliminary results indicate that during peak hours, the system can reduce vehicle waiting times at intersections by up to 50%. This work serves as a reference for developing intelligent and sustainable transportation systems.

The Third Generation Partnership Project (3GPP) has recently announced its Release 16, which introduces advanced functionalities to support the cellular vehicle to everything (C-V2X) technology. C-V2X allows direct communication between vehicles through the sidelink operation. This appears as an option to DSRC technologies; both are key wireless technologies that play a vital role in implementing and deploying advanced driving applications. This paper presents a thorough review of the available open-source frameworks intended for the performance evaluation of C-V2X protocols and V2X applications. For this, we consider validated OMNeT++-based simulation libraries and frameworks: SimuLTE, OpenCV2X, Artery-C, 5G-Sim-V2I/N, and Simu5G. We focus on the different frameworks' support regarding advanced V2X communications on 5G mobile networks.

Mobile Ad-hoc Networks (MANETs) exhibit a limited wireless transmission range due to the interference present in the channel and the packets lost due to transmission errors. Diversity reception is a common technique in many radio communication systems, fixed or mobile, which improves signal reception quality. Although Maximum Ratio Combining (MRC) is a well-known diversity technique, its implementation for the ns-3 network simulator has not been published in the open technical literature given its complexity. In this sense, the main contribution of this work is an inexpensive implementation of MRC diversity reception in the ns-3 network simulator. To this end, we have used a single Nakagami-m fading channel to model the resulting received signal after using MRC to the copies of the transmitted signal. The proposed implementation is then evaluated in the context of two classic scenarios. The first one is a static linear chain topology network, and the second one is a MANET scenario. The performance evaluation confirms the correct implementation of our proposal and shows significant improvements in terms of network transit time and packet delivery ratio.

Simulations are the first approach used by the research community to evaluate mobile ad hoc networks. Particularly, vehicular ad hoc networks (VANETs) are a singular type of mobile ad hoc networks that raise technical challenges, for instance, in the context of vehicular mobility models. When assessing VANETs, realistic vehicular models are essential to produce meaningful evaluation results. In this context, realistic vehicles' mobility includes re-routing capabilities that allow vehicles to re-compute their routes in front of specific traffic conditions (e.g., traffic jams). In this paper, we provide a thorough analysis of the influence of enabling re-routing properties on (i) the mobility of the vehicle and (ii) on the connections of the vehicular network. For this, we use the road traffic simulator SUMO to generate vehicular traces, and then we will analyze the connectivity of the vehicular network employing well-known graph metrics. Our results provide insights about the behavior of the vehicle's mobility and the nodes' connectivity.

Most of the classic fading variables can be obtained through Nakagami-m distribution and the sum of them has a pivotal role in the analytical performance evaluation of many practical wireless applications. However, the exact probability density function (PDF) of this sum of fading variables could be difficult to obtain. In this paper, we investigate the performance of the Maximum Likelihood Estimation to find a simple accurate approximation to the probability density function of the sum of Nakagami-m random variables. This approach provides expressions that can be used straightforwardly in the performance analysis of a number of wireless communication systems including multibranch receivers such as Maximal Ratio Combining and Equal Gain Combining, for which we present the application of the proposed framework. Numerical simulations show that our proposed method outperforms the well- known approach based on moment-matching method in terms of accuracy and simplicity. Moreover, the easiness of our proposal makes it suitable to be incorporated in network simulators to model and configure several wireless environments without additional computational complexity.

ABSTRACT Message encryption does not prevent eavesdroppers from unveiling who is communicating with whom, when, or how frequently, a privacy risk wireless networks are particularly vulnerable to. The Crowds protocol, a well‐established anonymous communication system, capitalizes on user collaboration to enforce sender anonymity. This work formulates a mathematical model of a Crowd‐like protocol for anonymous communication in a lossy network, establishes quantifiable metrics of anonymity and quality of service (QoS), and theoretically characterizes the trade‐off between them. The anonymity metric chosen follows the principle of measuring privacy as an attacker's estimation error. By introducing losses, we extend the applicability of the protocol beyond its original proposal. We quantify the intuition that anonymity comes at the expense of both delay and end‐to‐end losses. Aside from introducing losses in our model, another main difference with respect to the traditional Crowds is the focus on networks with stringent QoS requirements, for best effort anonymity, and the consequent elimination of the initial forwarding step. Beyond the mathematical solution, we illustrate a systematic methodology in our analysis of the protocol. This methodology includes a series of formal steps, from the establishment of quantifiable metrics all the way to the theoretical study of the privacy QoS trade‐off. Copyright © 2013 John Wiley & Sons, Ltd.