The rapid adoption of QUIC as a transport protocol has transformed content delivery by reducing latency, enhancing congestion control (CC), and enabling more efficient multiplexing. With the advent of 5G networks, which support ultra-low latency and high bandwidth, streaming high-resolution video at 4K and beyond has become increasingly viable. However, optimizing Quality of Experience (QoE) in mobile networks remains challenging due to the complex interactions among Adaptive Bit Rate (ABR) schemes at the application layer, CC algorithms at the transport layer, and Radio Link Control (RLC) queuing at the link layer in the 5G network. While prior studies have largely examined these components in isolation, this work presents a comprehensive analysis of the impact of modern active queue management (AQM) strategies, such as RED and L4S, on video streaming over diverse QUIC implementations—focusing particularly on their interaction with the RLC buffer in 5G environments and the interplay between CC algorithms and ABR schemes. Our findings demonstrate that the effectiveness of AQM strategies in improving video streaming QoE is intrinsically linked to their dynamic interaction with QUIC implementations, CC algorithms and ABR schemes—highlighting that isolated optimizations are insufficient. This intricate interdependence necessitates holistic, cross-layer adaptive mechanisms capable of real-time coordination between network, transport and application layers, which are crucial for leveraging the capabilities of 5G networks to deliver robust, adaptive, and high-quality video.

Low Earth Orbit (LEO) constellations are pivotal for the global connectivity of Internet of Things (IoT) networks. They facilitate Direct-to-Satellite (DtS) communications for ground nodes and address the absence of terrestrial infrastructure in remote regions. Although LoRa-based solutions provide low-cost connectivity to constrained devices in DtS-IoT networks, scalability remains a significant challenge due to heavy channel congestion associated with large-scale deployments. The LoRa Optimistic Collision Information-based (L-OCI) mechanism has been designed to estimate efficiently the network size of a LoRa-based DtS-IoT deployment. It enables a passing satellite to gauge the potential congestion in the served region by estimating the number of active ground nodes within its coverage area. However, this mechanism was devised to operate assuming a single LEO satellite. This paper introduces the constellation LOCI (CL-OCI), a new methodology for network size estimation designed for LEO satellite constellations. We thoroughly tested CL-OCI using FLoRaSat, a discrete-event satellite constellation simulator with realistic orbital DtS-IoT scenarios. Results indicate a substantial improvement in scalability, doubling the maximum number of nodes CL-OCI can estimate, and a sevenfold reduction in energy wasted due to collided transmissions compared to the baseline single-satellite L-OCI.

The worldwide adoption of the Internet of Things (IoT) depends on the massive deployment of sensor nodes and timely data collection. However, installing the required ground infrastructure in remote or inaccessible areas can be economically unattractive or unfeasible. Cost-effective nanosatellites deployed in low Earth orbits (LEOs) are emerging as an alternative solution: on-board IoT gateways provide access to remote IoT devices, according to direct-to-satellite IoT (DtS-IoT) architectures. One of the main challenges of DtS-IoT is to devise communication protocols that scale to thousands of highly constrained devices served by likewise constrained orbiting gateways. In this article, we tackle this issue by first estimating the (varying) size of the device set underneath the (mobile) nanosatellite footprint. Then, we demonstrate the applicability of the estimation when used to intelligently throttle DtS-IoT access protocols. Since recent works have shown that MAC protocols improve the throughput and energy efficiency of a DtS-IoT network when a network size estimation is available, we present, here, a novel and computationally efficient network size estimator in DtS-IoT: our optimistic collision information (OCI)-based estimator. We evaluate OCI’s effectiveness with extensive simulations of DtS-IoT scenarios. Results show that when using network size estimations, the scalability of a frame-slotted Aloha-based DtS-IoT network is boosted eightfold, serving up to$4 \times 10^{3}$devices, without energy efficiency penalties. We also show the effectiveness of the OCI mechanism given realistic detection ratios and demonstrate its low computational cost implementation, making it a strong candidate for network estimation in DtS-IoT.

The static context header compression and fragmentation (SCHC) framework has been recently designed by the Internet engineering task force (IETF). SCHC provides adaptation layer functionality intended to efficiently support IPv6-based and other applications over low power wide area network (LPWAN) technologies. As of the writing, technology-specific profiles are being standardized in order to describe how SCHC can be tailored when used over a given underlying technology. In this article, we provide the first performance evaluation of SCHC over Sigfox, a flagship LPWAN technology. We focus on the main SCHC over Sigfox fragmentation mode, called ACK-on-Error, which offers low overhead, reliability, and reassembly functionalities. We provide a theoretical analysis and an experimental evaluation in real environments that correspond to two geographical zones with different Sigfox radio settings: 1) Barcelona (Spain) and 2) Santiago (Chile). The study focuses on modeling and evaluating packet transfer times, and the required number of uplink and downlink messages. The results show that a small change in packet sizes may significantly affect the transfer times, especially when no duty-cycle restrictions are enforced. Also, we observe that, under certain conditions, an increase in the fragment loss rate (FLR) may decrease the packet transfer time, and that the number of uplink and downlink messages is not proportional to such increase due to the fact that downlink messages are device-driven. The results provide useful insights for researchers, developers, implementers, and providers, with applicability to the application design, network planning, and resource management of Internet of Things (IoT) solutions.

Internet of Everything (IoE) brings unprecedented challenges regarding scability, mobility, availability, and security to wireless communications. Cybertwin emerges as a promising paradigm for the next-generation mobile network, i.e., 6G. Basically, it serves as the communication anchor of a user at the edge and performs fundamental authentication and network resources control functionalities. Cybertwin is also an indispensable enabler of the cloud native network paradigm and can efficiently support the digital twin and metaverse. With cybertwin, heterogeneous access networks can be easily exploited in a synergic manner, such that advanced applications, such as multiscreen multistream rich media delivery, can be realized with guaranteed QoS. Furthermore, a user’s activities in cyberspace can be recorded naturally which becomes his/her/its digital asset. In the future, cybertwin may become the personal assistant and even an immortal second life of the user.

In this work, we present a comparative study of two strategies for opportunistic vehicular access over TV White Spaces (TVWS) spectrum, in the presence of fixed secondary networks. When the vehicular network meets other opportunistic users in the same TVWS channel, the first strategy is searching for a TVWS channel for exclusive vehicular access, while the other approach explores the coexistence between the vehicular network and the fixed secondary network. To carry out the evaluation of the strategies, we use the NS-3 network simulator, including some of the cognitive radio modules developed. Results showed that, in the case of study, the strategy of coexistence between the vehicular network and other opportunistic users over the TVWS channel (i.e., sharing the same TV channel) reduces the average access channel delay up to 15% and the average packet loss up to 17%.

The initiatives of cycling infrastructure enhancements around the world reveal a consistent interest in promoting cycling to transition toward sustainable lifestyles and safe multi-modal commuting. Accordingly, proposals for cyber-physical systems for smart cycling are also growing, providing solutions to make cycling a safer and better experience for cyclists. However, most existent solutions address single cyclist problems rather than group cycling issues. It is evident that further work is needed to improve safety and comfort for groups of cyclists traveling on busy urban bicycle paths or dedicated bicycle highways. In this paper, we position the concept of technology-assisted cooperative cycling. We introduce a platoon-based cyclist cooperative system that provides safe and efficient coordination for groups of cyclists. We present the results of an experimental prototype tested on real cyclists as well as comprehensive simulations that test the performance of our solution in different scenarios. We demonstrate that our system is feasible to implement and tolerates the human error factor while it is still able to achieve a constant spacing policy. Coordinated platoons of bicycles can be extremely useful to maximize the positive impact of green waves of traffic lights for cyclists and can be extended to groups of two-wheeled vehicles, including mopeds and self-balanced electric vehicles.

The supporting infrastructure and communications technologies for vehicular networking contexts are heterogeneous by nature. Large coverage access networks, such as 3G/4G, coexist with wireless local area networks and dedicated short-range communications. In such a scenario, we investigate the seamless provision of mobile Internet access and general IP services over the heterogeneous network, in particular for loosely coupling architectures. We propose a hybrid global mobility scheme that allows for the ongoing IP sessions to be transferred across dissimilar radio access networks that may belong to different administrative domains. In order to achieve the global mobility, our scheme combines host- and network-based mobility. The solution focuses on urban vehicular scenarios and enables seamless communications for in-vehicle networks, passengers with mobile devices, and users of public transportation commuting along the system. By means of analytical evaluations and simulations of realistic urban vehicular scenarios, we show that our hybrid scheme can achieve seamless IP communications for mobile Internet access over the heterogeneous vehicular network.

Network Mobility (NEMO) Basic Support Protocol (NBSP) provides mobility supports for mobile networks. NBSP is an extension of Mobile IPv6 which employs a centralized mobility management approach. It relies on a static and centralized home agent for signaling management and data forwarding. All data traffic traverse a centralized home agent, which leads to suboptimal routing, high packet overhead and latency, especially in nested NEMO (i.e. when the mobile networks connect to one another to reach the infrastructure). In this paper, we develop a network-based distributed mobility management (DMM) scheme for non-nested and nested NEMO scenarios, with the goal of mitigating the aforementioned problems. Additionally, the proposed scheme improves the packet delivery and location update (i.e., binding update) costs. The paper discusses in detail the scheme's design, operation mechanism and the performance evaluation analysis. The numerical results of the proposed scheme show significant improvement in packet overhead and latency as well as binding update and packet delivery costs.

In this paper, we propose an intersection-based connectivity-aware routing protocol (iCAR) for vehicular ad hoc networks (VANETs) to enable infotainment and interactive applications, as well as multi-hop Internet access in urban environments. iCAR is a novel protocol that takes into consideration real-time vehicular traffic information and the experienced packet delivery delay per road, in order to improve the routing performance by dynamically selecting roads with a guaranteed connectivity and a reduced delivery delay. This is achieved by deploying a microscopic view of vehicles location to proactively estimate roads connectivity and the minimum link lifetime per road. Detailed analysis and simulation-based evaluations show that iCAR significantly improves the network performance in terms of packet delivery ratio and end-to-end delay with a negligible cost of communication overhead.

Vehicular communication networks, such as the 802.11p and Wireless Access in Vehicular Environments (WAVE) technologies, are becoming a fundamental platform for providing real-time access to safety and entertainment information. In particular, infotainment applications and, consequently, IP-based communications, are key to leverage market penetration and deployment costs of the 802.11p/WAVE network. However, the operation and performance of IP in 802.11p/WAVE are still unclear as the WAVE standard guidelines for being IP compliant are rather minimal. This paper studies the 802.11p/WAVE standard and its limitations for the support of infrastructure-based IP applications, and proposes the Vehicular IP in WAVE (VIP-WAVE) framework. VIP-WAVE defines the IP configuration for extended and non-extended IP services, and a mobility management scheme supported by Proxy Mobile IPv6 over WAVE. It also exploits multi-hop communications to improve the network performance along roads with different levels of infrastructure presence. Furthermore, an analytical model considering mobility, handoff delays, collisions, and channel conditions is developed for evaluating the performance of IP communications in WAVE. Extensive simulations are performed to demonstrate the accuracy of our analytical model and the effectiveness of VIP-WAVE in making feasible the deployment of IP applications in the vehicular network.

Vehicular communications networks and the 802.11p/WAVE technology have become a fundamental platform for providing real-time access to safety and entertainment information in vehicular scenarios. In particular, IP-based infotainment applications are key to leverage the deployment costs of the 802.11p/WAVE network. However, the operation of IP in the standard 802.11p/WAVE and its throughput performance are still unclear, as the standard recommendations for the operation of IPv6 over WAVE are rather minimal. Consequently, this paper focuses on the provision of infrastructure-based IP communications in 802.11p/WAVE networks, and proposes the Vehicular IP in WAVE (VIP-WAVE) framework, which defines a new per-user assignment and mobility management of IPv6 addresses supported by Proxy Mobile IPv6 over WAVE, and exploits relay-aided communications to improve the network performance along roads with different levels of infrastructure presence. Extensive simulations are carried out to demonstrate the effectiveness of the proposed framework to enhance the performance of IP applications in the vehicular network.

In this paper, we propose EM3A, a novel scheme that guarantees the authenticity of a mobile node (MN) and a relay node (RN) in a multi-hop-enabled Proxy Mobile IP (PMIP) network. EM3A works in conjunction with a proposed scheme for key establishment, based on symmetric polynomials, to generate a shared secret key between MN and RN. This scheme achieves lower revocation overhead than that achieved by existing symmetric polynomial-based schemes. For a PMIP domain with n points of attachment, EM3A achieves t×2n-secrecy, whereas the existing authentication schemes achieve only t-secrecy. Computation and communication overhead analysis, as well as simulation results, demonstrate that EM3A achieves low authentication delay and is suitable for seamless multi-hop IP communications.

The inherent characteristics of vehicular networks, such as dynamic topology and high mobility, pose significant challenges for the deployment of delay-sensitive applications, e.g., video streaming, in urban Vehicular Ad-hoc Networks (VANET). In this paper, we propose an integrated network-layer scheme for seamless delivery of video packets in VANET. First, we propose a new quality-driven routing scheme for delivering video streams from a fixed network to a destination vehicle via multihop communications. The routing scheme aims to optimize the visual quality of the transmitted video frames by minimizing the distortion, the start-up delay, and the frequency of the streaming freezes. We further propose an efficient network mobility management scheme, which introduces a novel adaptation of Proxy Mobile IPv6 (PMIPv6) for multi-hop VANET scenarios, and incorporates a handover prediction mechanism. Numerical results are given to demonstrate that our integrated scheme can achieve a better performance for the video quality metrics, the handover delay and the signalling cost.

We present a novel mobility management scheme for seamless Internet access in urban vehicular scenarios. The scheme is based on Proxy Mobile IPv6 and Host Identity Protocol, and allows users to handoff within and across different administrative domains. We consider two types of nodes: legacy nodes with no mobility support (e.g., end devices that depend on the vehicle's mobile router for the support of mobility), and mobility-enabled nodes (e.g., passengers that commute from/to vehicles and terminal stations). The main advantage of our scheme is to enable the inter-domain handover of both types of nodes with a reduced signalling overhead and packet losses. Performance evaluations demonstrate that our scheme improves the handover latency and packet losses compared to other global mobility management protocols.

The Vehicular Ad-hoc NETworks (VANET) consist of a spontaneous association of a group of vehicles with wireless connection, they move and dynamically change their positions, exchanging data between each other. These networks were thinking as autonomous network segments with flat addressing schemes, however, its study has shown the benefits obtained by interconnecting them to fixed network segments and Internet. This article will revise by means of using a simulation tool, the global improvements in QoS network metrics, achieved through the use of a mutipath routing protocol. The model has a fixed network segment (Internet), two reactive gateways and two IPv6 VANET hierarchical network segements, whose nodes show a high degree of mobility, such as vehicles in an urban environment.