1,721,066 research outputs found
Editorial of the MDPI JSAN Special Issue on Wireless Technologies Applied to Connected and Automated Vehicles
No full textConnectivity and automation are two aspects that, together, will revolutionize the transport system [...
Visible Light Communications as a Complementary Technology for the Internet of Vehicles
No full textThe paradigm of connected vehicles is moving from research to implementation, thus enabling new applications that start from safety improvement and widen to the so called Internet of vehicles (IoV). The candidate enabling technologies in the radio frequency (RF) bands are cellular and short range technologies. However, the limited bandwidth shared among several applications pushes researchers to look at new technological solutions. To this end, an option is provided by visible light communication (VLC). Based on the use of the light emission diodes (LEDs) that are already available on the majority of vehicles, VLC would enable short range communication in large, unlicensed, and uncongested bands with limited costs. In this work we first highlight the main properties of VLC in vehicular networks and revise the state of the art focusing on both the IEEE 802.15.7 standard and on the performance demonstrated by field tests that have been conducted worldwide. Then, we discuss the limitations of using VLC for pure vehicular visible light networks (VVLNs) and its application as complementary technology, to be implemented with other wireless standards in future heterogeneous vehicular networks. Finally, we show numerical results provided by simulations in a realistic urban scenario focusing, as a case study, on the crowd sensing vehicular network application with VLC added to short range IEEE 802.11p technology. Results demonstrate that the addition of VLC improves the performance of a conventional vehicular network based only on IEEE 802.11p
Performance evaluation of softer vertical handovers in multiuser heterogeneous wireless networks
No full textIn the future fifth generation (5G) networked society, devices will integrate heterogeneous radio access technologies (RATs) to improve the network performance and the user quality of experience.In this paper, we focus on softer vertical handover (SRVH), discussing its feasibility and its performance in a multiuser scenario. Specifically, a new taxonomy for vertical handovers is proposed to resolve ambiguities in current terminology and technical issues related to SRVH implementation are discussed. Then, a simple but accurate analytical model is proposed to evaluate the performance of SRVH and results are provided with reference to best effort services in the presence of two RATs. Two case studies are considered, a mobile controlled approach with uncoordinated RATs and a network controlled approach with coordination among RATs. Results demonstrate that SRVHs are useful to allow finer granularity in resource allocation when there is coordination among RATs, although they fail to provide throughput improvements if they are selfishly performed by mobile terminals
Performance analysis of IEEE 802.11p preamble insertion in C-V2X sidelink signals for co-channel coexistence
Full text linkSpectrum scarcity is one of the main challenges of future wireless technologies. When looking at vehicle-to -everything (V2X), this is amplified as spectrum sharing could impact road safety and traffic efficiency. It is therefore of particular importance to study solutions that allow the coexistence, in the same geographical area and in the same channels, of what are today the main V2X access technologies, namely IEEE 802.11p and long term evolution (LTE)-V2X sidelink Mode 4. In this paper, in addition to studying the impact of mutual interference, which is found to have a strong impact especially on the former and under congested channel conditions, a mitigation solution is extensively studied. The solution is based on the insertion of the IEEE 802.11p preamble at the beginning of each LTE-V2X sidelink transmission. The proposal, which is also under discussion within the standardization bodies, requires no changes to the IEEE 802.11p protocol stack and minor changes to LTE-V2X sidelink. This solution is directly applicable to upcoming IEEE 802.11bd and extendable to new radio (NR)-V2X sidelink. The paper shows, through analysis and simulations in free-flow and dense scenarios, that the proposal enables mitigation of collisions caused by co-channel coexistence under low and high load conditions. The improvement is guaranteed even in cases of congestion when combined with additional countermeasures. Regarding the latter aspect, in particular, different approaches are compared, demonstrating that acting on the congestion control mechanisms is a simple but effective solution
A Raspberry Pi-Based Platform for Signal Processing Education [SP Education]
No full textOne of the most important application areas of signal processing (SP) is, without a doubt, the software-defined radio (SDR) field [1]-[3]. Although their introduction dates back to the 1980s, SDRs are now becoming the dominant technology in radio communications, thanks to the dramatic development of SP-optimized programmable hardware, such as field-programmable gate arrays (FPGAs) and digital signal processors (DSPs). Today, the computational throughput of these devices is such that sophisticated SP tasks can be efficiently handled, so that both the baseband and intermediate frequency (IF) sections of current communication systems are usually implemented, according to the SDR paradigm, by the FPGA's reconfigurable circuitry (e.g., [4]-[6]), or by the software running on DSPs
Configuration Issues and Best Effort Performance Investigation of IEEE 802.16e
No full textTh e IEEE 802.16 standard family enables the convergence of fi xed and mobile broadband networks through a common wide area broadband access technology and a flexible network architecture. In this paper we provide an overview of the recent IEEE 802.16e-2005 amendment, aimed at supporting user mobility, and we discuss several issues related to a proper choice of system parameters and strategies to be adopted to fully exploit the technology potential. Moreover, we propose a scheduling strategy aimed at providing a fair service to best effort users. The effectiveness of this proposal is shown via simulation
A software defined radio platform with Raspberry Pi and Simulink
No full textThe Raspberry Pi is a low cost single-board computer that gained recently the attention of hobbyists and practitioners, especially for file server and media server applications. Thanks to the free support package released by MathWorks, it is fully supported by Simulink, hence it can be programmed according to the model-based design paradigm. This means that also users with no programming skills can design and implement their own applications on Raspberry Pi boards. In this paper we show how Raspberry Pi's boards can be used, jointly with Simulink, to easily implement digital communication systems. This allows the realization of practical experiences, intended for use within telecommunication courses, that provide a viable low-cost way to introduce students to the software-defined radio paradigm
Virtual road side units for geo-routing in VANETs
No full textVehicular networking is the new key context to offload the cellular network of the great amount of contents produced on the move. In this paper, we focus on the exploitation of vehicle-to-vehicle communications to deliver part of the data produced on board to the road side units (RSUs) deployed in the scenario, avoiding, as much as possible, the adoption of the cellular network. Specifically, we propose a novel routing algorithm that is based on the greedy forwarding approach and uses virtual RSUs to overcome the problem of the local minima. The proposed algorithm allows data to be redirected through optimized directions with limited amount of added information. In addition, system optimization can be performed via software and the choice of the RSU positions becomes less critical. The effectiveness of the proposed algorithm is demonstrated through simulations performed using realistic vehicular traces in two European cities, showing that the proposed solution increases the amount of data transmitted through the vehicular networks
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