Development of maneuver cooperation strategies is essential for enhancing traffic safety and efficiency. In a Vehicle-To-Everything (V2X) ecosystem, Maneuver Coordination Messages (MCM) allow road users to coordinate trajectory intentions based on decision-making mechanisms so they can effectively solve complex interactions such as unsignalized intersection crossings or lane changes. As these mechanisms are still in the early stages of development, research continues exploring their effectiveness and feasibility. In this paper, a Decentralized Maneuver Coordination Service (D-MCS) implementation is evaluated in real-world conditions where Vulnerable Road Users (VRUs) and emergency vehicles are taken into account, assessing the efficiency of the cooperative algorithm by demonstrating a reduction in execution time to complete the maneuvers. The results of the experiments also demonstrate that the proposed DMCS achieves a significant reduction in maneuver coordination time compared to a centralized MCS and improves traffic flow and VRU safety by allowing vehicles to proactively adjust their maneuvers.

To facilitate the widespread adoption of Cooperative Intelligent Transport Systems (C-ITS) and applications, deploying infrastructure alongside roadways to support vehicle communication becomes imperative. This infrastructure, leveraging Multi-access Edge Computing (MEC), necessitates communication infrastructure integrating two technologies: cellular networks and C-V2X (Cellular Vehicle-to-Everything), thus embracing a Vehicle-to-Infrastructure-to-Vehicle (V2I2V) approach. This paper presents an analysis of various Road-Side Units (RSUs) devices from different manufacturers to be used in these architectures, focusing on two key aspects. Firstly, their user-friendliness to enable programming for seamless integration with the communication protocol stack executed in the MEC. Secondly, their ability to meet the transmission capacity demands in high-density scenarios.

With the advent of Connected and Autonomous Vehicles (CAVs) comes the very real risk that these vehicles will be exposed to cyber-attacks by exploiting various vulnerabilities. This paper gives a technical overview of the H2020 CARAMEL project (currently in the intermediate stage) in which Artificial Intelligent (AI)-based cybersecurity for CAVs is the main goal. Most of the possible scenarios are considered, by which an adversary can generate attacks on CAVs, such as attacks on camera sensors, GPS location, Vehicle to Everything (V2X) message transmission, the vehicle's On-Board Unit (OBU), etc. The counter-measures to these attacks and vulnerabilities are presented via the current results in the CARAMEL project achieved by implementing the designed security algorithms.

Vehicular communications will foster mobility services and enable mass adoption of future autonomous vehicles, interchanging huge amount of data acquired from vehicles’ sensors. 3GPP Release 14 presents the first standard for supporting V2X in LTE. Several enhancements are introduced, including a new arrangement of the physical resource grid, where subchannels are the minimum resource unit instead of Resource Blocks. The resource grid is defined by several design parameters, some of them with constraints imposed by 3GPP specifications, that affect the maximum message transmission rate and efficiency of the system. Moreover, the optimum choice of these parameters is closely linked to message length, which is another variable parameter. This paper provides an analysis of the relationship between these design parameters (Resource Block per Subchannel, Transport Block Size Index, and coding rate), message size, and the system’s maximum capacity and efficiency. In doing so, we do not consider channel reuse or radio transmission characteristics because the focus of this paper is trying to find the resource grid design parameters that optimize system capacity, which is a very important aspect to consider by V2X operators.

Duty-cycled Medium Access Control (MAC) protocols certainly improve the energy efficiency of wireless networks. However, most of these protocols still suffer from severe degrees of overhearing and idle listening. These two issues prevent optimum energy usage, a crucial aspect in energy-constrained wireless networks such as wireless sensor networks (WSNs). Wake-up radio (WuR) systems drastically reduce these problems by completely switching off the nodes' microcontroller unit (MCU) and main radio transceiver until a secondary, extremely low-power receiver is triggered by a particular wireless transmission, the so called wake-up call. Unfortunately, most WuR studies focus on theoretical platforms and/or custom-built simulators. Both these factors reduce the associated usefulness of the obtained results. In this paper, we model and simulate a real, recent, and promising WuR hardware platform developed by the authors. The simulation model uses time and energy consumption values obtained in the laboratory and does not rely on custom-built simulation engines, but rather on the OMNET++ simulator. The performance of the WuR platform is compared to four of the most well-known and widely employed MAC protocols for WSN under three real-world network deployments. The paper demonstrates how the use of our WuR platform presents numerous benefits in several areas, from energy efficiency and latency to packet delivery ratio and applicability, and provides the essential information for serious consideration of switching duty-cycled MAC-based networks to WuR.

The use of duty-cycling in Medium Access Control (MAC) protocols effectively helps improving the energy efficiency of wireless networks. However, while the benefits of these protocols are unquestionable, most of them still suffer from overhearing and idle listening, two issues that prevent duty-cycled systems from achieving optimum energy usage, which is a crucial aspect in specific types of wireless networks such as Wireless Sensor Networks (WSN).Wake-up Radio (WuR) systems have been employed recently to overcome these issues. Under this approach, the nodes' MicroController Unit (MCU) and main radio transceiver are completely switched off and only activated when a secondary, extremely low-power receiver in the node is triggered by a particular wireless transmission. Wake-up Radio systems allow for drastic energy savings since receiver nodes are only activated on-demand, maximizing their battery lifetimes. In this paper, we have modeled and simulated a real, recent and promising WuR hardware platform based on its time and energy consumption characterization. By comparing such WuR approach to B-MAC and IEEE 802.15.4, two well-known and widely employed MAC protocols, we show it effectively out-performs the conventional WSN MAC approaches in terms of energy efficiency. To the best of authors' knowledge, this is the first study to include a comparative analysis for multi-hop networks based on a real WuR platform, which shows WuR systems represent an energy-efficient solution that also provides a good tradeoff between latency, packet delivery ratio and applicability..

Energy-efficient operation is a challenge for wireless sensor networks (WSNs). A common method employed for this purpose is duty-cycled operation, which extends battery lifetime yet incurs several types of energy wastes and challenges. A promising alternative to duty-cycled operation is the use of wake-up radio (WuR), where the main microcontroller unit (MCU) and transceiver, that is, the two most energy-consuming elements, are kept in energy-saving mode until a special signal from another node is received by an attached, secondary, ultra-low power receiver. Next, this so-called wake-up receiver generates an interrupt to activate the receiver node's MCU and, consequently, the main radio. This article presents a complete wake-up radio design that targets simplicity in design for the monetary cost and flexibility concerns, along with a good operation range and very low power consumption. Both the transmitter (WuTx) and the receiver (WuRx) designs are presented with the accompanying physical experiments for several design alternatives. Detailed analysis of the end system is provided in terms of both operational distance (more than 10 m) and current consumption (less than 1 μA). As a reference, a commercial WuR system is analyzed and compared to the presented system by expressing the trade-offs and advantages of both systems.

Wake-up radios present a promising alternative to traditional duty-cycle approaches, by reducing overhearing and by eliminating idle listening completely. However, energy-efficient operation of the wake-up mechanism is required for the success of such systems. In particular, addressing is an important component of the wake-up procedure that can consume a significant portion of the energy required. Hence, in this paper we propose a novel energy-efficient scheme for addressing. The proposed method is called Time-Knocking (TicK), since it utilizes the time duration of the MicroController Unit (MCU) sleeping to encode an address. In this paper, it is shown through mathematical analysis that TicK is much more energy efficient compared to the two common addressing mechanisms: MCU-decoding and correlator-based addressing. For realistic performance evaluations, physical measurements are performed to extract the parameter values of each method or the parameter values from well-documented off-the-shelf devices are used. TicK enables significant energy savings, especially in environments where false addressing initiations are frequent due to interference or where multiple nodes are addressed frequently.

Abstract Since the advent of the first IEEE 802.11 standard for WLANs, several papers have been presented that evaluate the IEEE 802.11 DCF access method. In realistic WLAN environments frame errors usually occur due to non‐ideal channel conditions; in this way, papers including adverse transmission conditions in the evaluation have been published later in the literature. In this paper, we review existent analytical models that include the influence of transmission errors in IEEE 802.11 DCF performance. We modify current models and provide a more accurate analysis, thus allowing the evaluation in single rate and multi‐rate scenarios with stations subject to different link error conditions. Moreover, this paper exposes the unfairness problem that arises in IEEE 802.11 DCF networks with stations subject to different transmission conditions through analytical and simulation results. Stations are not able to distinguish collisions from failed transmissions due to link errors; both result in a missing ACK and, consequently, the transmitting stations apply the exponential backoff algorithm. This fact leads to a lower performance for stations in worse transmission conditions. Copyright © 2010 John Wiley & Sons, Ltd.

IEEE 802.11 Wireless LANs (WLANs) are highly sensitive to Denial of Service (DoS) attacks carried out with jamming devices. In this paper we focus on 2.4GHz wideband constant jammers. The interest in the wideband jammer lies in the fact that it beats all possible channels at the same time, leaving no possible escape following traditional channel-switching defenses. After studying and developing an effective detection mechanism, we propose the implementation of a load balancing technique based on cell breathing for mitigating the harmful effects of the jammer over an IEEE 802.11 WLAN. Cell breathing is achieved by dynamically tuning the transmission power to adjust the size of a WLAN cell.

In nowadays communication technologies, one of the main challenges to overcome is how to translate theoretical algorithms, designed protocols, existing hardware products from different manufacturers and the already knowhow into innovative applications that can produce a benefit for the user and for the commercializing firm. Following this topic, the present paper introduces an application that combines different emerging technologies: wireless mesh networks, multihop routing and adaptation of streaming delivery with the objective to create a tool for effective marketing campaigns.

In atypical deployment of IEEE 802.11 wireless LANs in the infrastructure mode, an access point acts as abridge between the wireless and the wired parts of the network. Under the current IEEE 802.11 Distributed Coordination Function (DCF) access method, which provides equal channel access probability to all devices in a cell, the access point cannot relay all the frames that it receives on the downlink. This causes significant unfairness between upload and download connections, long delays, and frame losses. This unfairness problem comes from the not-so-complex interaction of transport-layer protocols with the MAC-layer access method. The main problem is that the access point requires more transmission attempt probability than wireless stations for correct operation at the transport layer. In this paper, we propose to solve the unfairness problem in a simple elegant way at the MAC layer. We define the operation of an Asymmetric Access Point that benefits from a sufficient transmission capacity with respect to wireless stations so that the overall performance improves. The proposed method of operation is intrinsically adaptive so that when the access point does not need the increased capacity, it is used by wireless stations. We validate the proposed access method by simulation to compare it with other solutions based on IEEE 802.11e. Unlike many papers in this domain, which only validate MAC-layer modifications through simulation or analytical modeling, we provide measurement data gathered on an experimental prototype that uses wireless cards implementing the proposed method.

In this paper, we present an evaluation of chosen wireless LAN access methods involving stations with different bit error rates: n-1 stations in ideal transmission conditions (BER = 0) and 1 station with a given bit error rate (BER ne 0). The simulation results show that the IEEE 802.11 DCF and its modifications (Slow Decrease, AOB) are very sensitive to transmission errors, whereas Idle Sense provides good channel access fairness: the value of the contention window is almost the same regardless of transmission errors, so that the throughput difference between stations subject to different bit error rates corresponds only to the proportion of lost frames.

In this paper, we address the issue of evaluating performance of wireless LANs in multicell scenarios. We try to understand the complex behavior of the DCF (distributed coordination function) access method defined in the IEEE 802.11 standard [1] and its modifications proposed for improving performance: slow decrease [2], asymptotically optimal backoff [3], and idle sense [4]. We analyze the influence of overlapping cells and large multicell environments on their performance. Our results show that the IEEE 802.11 DCF and its two modifications (slow decrease and AOB) exhibit important unfairness between stations close to the access point and those near the border of a neighbor cell. Idle Sense performs much better: it provides much better fairness than the IEEE 802.11 DCF and its modifications. It also obtains the highest throughput when stations adapt their bit rate to channel conditions.

In this paper we present constructions of traceability codes based on the Chinese Remainder Theorem. Taking into account the non-uniformity of the alphabet of the code, we derive a new expression for the minimum distance that allows us to provide a criterion to obtain traceability codes with the maximum number of code words. In order to make the traceability conditions as independent as possible of the code parameters, we also present a new family of non-uniform alphabet codes whose tracing capabilities only depend on the code length.

Actually, Wireless Local Area Networks (WLAN) are being extensively deployed in many places to provide easy access to Internet. Moreover, networks that span large buildings or campuses must comprise multiple cells. Surprisingly, multicell environments that correspond to realistic situations in highly deployed areas have received little attention in the literature.If we compare the system performance in a multicell scenario with its behavior in an isolated single cell, we can observe an important performance decrease that becomes higher with the growth of the transmission data rate employed and due to co-channel interference.In this paper, we propose some power control mechanisms to operate in IEEE 802.11 cellular networks. With the employment of such methods we aim at reducing the interference influence on network performance and at homogenizing the behavior of the stations placed at different spatial positions with respect to their access point. Results exposed show that the employment of such power control mechanisms leads to an important reduction in the interference level.

Technologies involved in Web information distribution services are evolving to adapt themselves to new user requirements. Usually, these new technologies are used separately. ELIN (electronic newspaper initiative) project is a European Commission funded project that tries to integrate the newest standards and technologies involved in multimedia delivery applied to web newspapers. It has as objective the delivery of any type of media format to any kind of user terminal in an efficient way. In order to do that, it takes the approach of using MPEG standards: MPEG-4 for video delivery, MPEG-7 for data classification and MPEG-21 for data management and adaptation. So it integrates the totality of solutions provided for the MPEG group.

Up to the present, several studies have been performed in order to provide prioritization of stations or classes of service for WLAN IEEE 802.11. The IEEE 802.11e draft specification aims to extend the original IEEE 802.11 MAC protocol to support QoS. One of the mechanisms for prioritizing traffic is the assignment of different AIFS times to each priority level. Nevertheless, the AIFSs employed are separated by values that are multiples of the slot time. Therefore, due to the fact that the backoff time counter is slotted, the different priority levels can attempt for transmission simultaneously. In this paper, we evaluate the performance of the IEEE 802.11e when its working procedure is desynchronized: we avoid that stations belonging to different priority levels attempt for transmission at the same time. We assign AIFS times that are separated by values that are not multiples of the slot time, in order to avoid collisions between the different priority levels. We present a mathematical model and simulation results for analyzing the performance of the differentiation mechanism proposed. The results show that it solves the strangulation of low priority traffic, fact that occurs in IEEE 802.11e EDCA. Moreover, this proposal leads to a significant increase in the performance of the system as a whole

Most studies about the performance of IEEE 802.11 consider scenarios of ad-hoc topology and networks where all stations have the same traffic load (symmetric traffic conditions). This paper presents a study of performance parameters of more realistic networks. We focus the attention on WLAN with infrastructure networks, where the traffic distribution is asymmetric. In this case, the traffic load at the access point is much heavier than that at user stations. These studies are more realistic because most nowadays installed WLAN are infrastructure topology type, due to the fact that they are used as access networks. In this case, the access point has to retransmit all incoming traffic to the basic service set and therefore its traffic load is higher. Finally, the paper presents the tuning of the contention window, taken from IEEE 802.11e, used to increase the system performance under asymmetric traffic conditions, and the proposal of an adaptive algorithm to adapt the MAC layer settings to the system traffic load

Most studies about the performance of IEEE 802.11 are limited to a single cell environment. Nevertheless, the idea of designing an outdoor cellular network based on WLAN IEEE 802.11 is very attractive, due to the several advantages that this technology presents: the low cost of the equipment, its operation in unlicensed spectrum and its higher data rates. In this paper, we study the possibility of designing an outdoor cellular network based on the IEEE 802.11g standard. We present its performance under different load conditions and compare this behavior with the results obtained in an isolated single cell environment, without co-channel interference. Finally, going a step further, this paper explores the IEEE 802.11g cellular network performance for different cluster sizes, as a method to reduce the interference influence on network's performance.

This paper is focused on the study of WLAN performance in IEEE 802.11 networks that are in a situation of asymmetric traffic, where the access point (AP) transmits much more than the user stations (US). This situation is very different from the symmetric one, wherein all the stations have the same traffic load. The paper also presents a discussion of the different mechanisms in order to increase AP priority under the asymmetric traffic situation.

Most studies of the performance of IEEE 802.11 consider scenarios of ad-hoc topology networks and do not contemplate the network broadcast information contained in beacon frames. The paper presents a study of the performance of a WLAN whose infrastructure's topology is such that the access point is in charge of broadcasting the beacon frames. Thus, it is more realistic than previous studies, because beacon frames are usually transmitted in order to announce control information and network identity. Furthermore, in the coverage area, user stations are likely to be working at different data rates, depending on their signal quality. Because beacon frames must be received by all stations, they are transmitted at the lowest data rate operating in the coverage area. The article introduces a mathematical method to calculate the influence of beacon frames on the total throughput, collision probability and delays of the IEEE 802.11g protocol. The model is validated by simulation analysis.

The paper presents an analysis of teletraffic variables in cellular networks. The variables studied are the time between two consecutive handoff arrivals and the handoff delay. These teletraffic variables are characterized by means of an advanced software simulator that models several scenarios assuming fixed channel allocation. Information about the quality of service is also provided. A large set of scenarios has been simulated and the characterization results derived from its study have been presented and analyzed.

The Digital European Cordless Telecommunication System (DECT) is gaining acceptance in environments different to the ones the system has been designed for. In particular outdoors environments as the radio local loop (RLL) or public cordless terminal mobility (CTM). The main difference between indoors, where DECT was supposed to work, and outdoors is that for this latter environment the signal propagation is not limited between walls and further studies have to be performed to determine its capacity. In this paper a study of a CTM system in an urban environment is presented. Static or mobile users appear on a surface with a regular distribution of buildings and streets. An evaluation of the traffic capacity and related parameters of the system is performed by simulation. The main focus is on the influence of different base station locations on the static or mobile terminals.