A vast number of advanced driver assistance systems are currently being developed, from platoon controllers to intersection assistants. All these systems depend on the vehicle's capability to accurately sense its environment. In order to overcome line of sight and other constraints of standard on-board vehicle sensors, Vehicle-to-Everything (V2X) communication has been introduced. Through concepts like collaborative positioning, cooperative awareness and collective perception, traffic participants are enabled to share data gathered by their sensors, permitting to significantly enhance their environmental perception. This paper is aimed at supporting the current standardization efforts at the European Telecommunications Standards Institute (ETSI) with respect to the latter. It analyzes the performance of the collective perception service in IEEE 802.11p networks in terms of its impact on the traffic participant's gained environmental perception and draws conclusions for the further development of the service.

The convergence of sensor-based vehicle automation and Inter-Vehicle Communication (IVC) will be a key to achieve the full automation of vehicles. In this paper we present a new method for the design and performance evaluation of Cooperative Automated Driving (CAD) systems, based on a bidirectional coupling of vehicle and network simulators (Webots and ns-3). The coupling exploits the comprehensive capabilities of the simulators at a reasonable computational complexity and allows simulating CAD systems with high accuracy. We demonstrate the capabilities of the simulation tool by a case study of convoy driving with automated vehicles using a fully distributed control algorithm and IVC. The study compares CAD-specific metrics (safety distance, headway, speed) for an ideal and a realistic communication channel. The simulation results underline the need of accurate modeling and give valuable insights for the design of CAD systems.

The combination of automated driving and Inter-Vehicle Communication (IVC) allows automated vehicles to drive cooperatively, thereby greatly enhancing their safety and traffic efficiency. Convoys are groups of automated vehicles which keep a multi-lane formation with decentralized control supported by IVC. The vehicle control algorithm of convoy vehicles requires up-to-date information about the neighbor vehicle dynamics; fast and efficient convoy communications enable the cooperative maneuvering of the automated vehicles. For this reason, we evaluate IVC in convoys of automated vehicles by defining performance metrics which quantify the reliability, latency and data age of convoy communications. Our results explore the trade-off between the convoy message frequency and the communication performance; whereas a high message frequency results in a higher number of lost messages and delay due to channel congestion, a low message frequency yields a higher data age of the information available to the vehicle controller. As a result, convoy algorithm designers should choose carefully the optimal value for the convoy message frequency as a function of the required communication performance and the convoy size.

Cooperation and information exchange will allow autonomous vehicles to increase their sensing range and maneuver coordinately, thereby greatly enhancing their safety and efficiency. The combination of autonomous driving and vehicular communications will enable Cooperative Autonomous Driving Systems (C-ADS) with stringent requirements. We present two new multi-hop forwarding algorithms specially suited to the dissemination of information in C-ADS: (i) Greedy Broadcast Forwarding, aimed to the distribution of packets within a geographical area, and (ii) Greedy Multicast Forwarding, which delivers packets only to the members of a vehicle group. A performance comparison of the proposed schemes with the broadcast forwarding algorithms defined in the ETSI GeoNetworking standard shows that Greedy Broadcast Forwarding achieves the highest reliability, while Greedy Multicast Forwarding yields the lowest traffic overhead in the considered scenario. These results indicate that the proposed forwarding algorithms are promising candidates to enable multi-hop communications in future C-ADS.

The GeoNetworking protocol provides single-hop and multi-hop communication in vehicular ad hoc networks based on IEEE 802.11p/ITS-G5. It has been standardized by the ETSI Technical Committee ITS as part of its Release 1 set of specifications and is expected to be deployed in the next years. This paper presents a performance evaluation of the GeoNetworking protocol in its recently published version. Our study assesses the performance of the broadcast forwarding algorithms for multi-hop packet transport that are used to disseminate information in geographical areas for road safety and traffic efficiency applications. From the algorithms specification in the standard, we derive six variants with different combinations of protocol mechanisms with increasing complexity and assess their performance in terms of reliability, latency, and overhead. The algorithms are evaluated in a reference freeway scenario with bidirectional road traffic and a realistic trace-based mobility model with varying vehicle density. The obtained results indicate that the combination of contention-based and greedy forwarding shows the best overall performance; further functional improvements have a limited performance gain in the studied scenario.

Graphene is enabling a plethora of applications in a wide range of fields due to its unique electrical, mechanical, and optical properties. Among them, graphene-based plasmonic miniaturized antennas (or shortly named, graphennas) are garnering growing interest in the field of communications. In light of their reduced size, in the micrometric range, and an expected radiation frequency of a few terahertz, graphennas offer means for the implementation of ultra-short-range wireless communications. Motivated by their high radiation frequency and potentially wideband nature, this paper presents a methodology for the time-domain characterization and evaluation of graphennas. The proposed framework is highly vertical, as it aims to build a bridge between technological aspects, antenna design, and communications. Using this approach, qualitative and quantitative analyses of a particular case of graphenna are carried out as a function of two critical design parameters, namely, chemical potential and carrier mobility. The results are then compared to the performance of equivalent metallic antennas. Finally, the suitability of graphennas for ultra-short-range communications is briefly discussed.

Graphene is a promising material which has been proposed to build graphene plasmonic miniaturized antennas, or graphennas, which show excellent conditions for the propagation of Surface Plasmon Polariton (SPP) waves in the terahertz band. Due to their small size of just a few micrometers, graphennas allow the implementation of wireless communications among nanosystems, leading to a novel paradigm known as Graphene-enabled Wireless Communications (GWC). In this paper, an analytical framework is developed to evaluate how the channel capacity of a GWC system scales as its dimensions shrink. In particular, we study how the unique propagation of SPP waves in graphennas will impact the channel capacity. Next, we further compare these results with respect to the case when metallic antennas are used, in which these plasmonic effects do not appear. In addition, asymptotic expressions for the channel capacity are derived in the limit when the system dimensions tend to zero. In this scenario, necessary conditions to ensure the feasibility of GWC networks are found. Finally, using these conditions, new guidelines are derived to explore the scalability of various parameters, such as transmission range and transmitted power. These results may be helpful for designers of future GWC systems and networks.

Nanonetworks, the interconnection of nanosystems, are envisaged to greatly expand the applications of nanotechnology in the biomedical, environmental and industrial fields. However, it is still not clear how these nanosystems will communicate among them. This work considers a scenario of Diffusion-based Molecular Communication (DMC), a promising paradigm that has been recently proposed to implement nanonetworks. In a DMC network, transmitters encode information by the emission of molecules which diffuse throughout the medium, eventually reaching the receiver locations. In this scenario, a pulse-based modulation scheme is proposed and two techniques for the detection of the molecular pulses, namely, amplitude detection and energy detection, are compared. In order to evaluate the performance of DMC using both detection schemes, the most important communication metrics in each case are identified. Their analytical expressions are obtained and validated by simulation. Finally, the scalability of the obtained performance evaluation metrics in both detection techniques is compared in order to determine their suitability to particular DMC scenarios. Energy detection is found to be more suitable when the transmission distance constitutes a bottleneck in the performance of the network, whereas amplitude detection will allow achieving a higher transmission rate in the cases where the transmission distance is not a limitation. These results provide interesting insights which may serve designers as a guide to implement future DMC networks.

Nanotechnology is enabling the development of devices in a scale ranging from a few to hundreds of nanometers. The nanonetworks that result from interconnecting these devices greatly expand the possible applications, by increasing the complexity and range of operation of the system. Molecular communication is regarded as a promising way to realize this interconnection in a bio-compatible and energy efficient manner, enabling its use in biomedical applications. However, the transmission range of molecular signals is strongly limited due to the large and inherent losses of the diffusion process. In this paper, we propose the employment of Quorum Sensing so as to achieve cooperative amplification of a given signal. By means of Quorum Sensing, we aim to synchronize the course of action of a certain number of emitters, which will transmit the same signal. Under the assumption of a linear channel, such signal will be amplified and thus the transmission range will be consequently extended. Finally, we validate our proposal through simulation.

Diffusion-based molecular communication is a promising bio-inspired paradigm to implement nanonetworks, i.e., the interconnection of nanomachines. The peculiarities of the physical channel in diffusion-based molecular communication require the development of novel models, architectures and protocols for this new scenario, which need to be validated by simulation. With this purpose, we present N3Sim, a simulation framework for diffusion-based molecular communication. N3Sim allows to simulate scenarios where transmitters encode the information by releasing molecules into the medium, thus varying their local concentration. N3Sim models the movement of these molecules according to Brownian dynamics, and it also takes into account their inertia and the interactions among them. Receivers decode the information by sensing the particle concentration in their neighborhood. The benefits of N3Sim are multiple: the validation of channel models for molecular communication and the evaluation of novel modulation schemes are just a few examples.