Francisco Vázquez-Gallego

• CTTC Catalan Telecommunications Technology Centre

In cross-border mobility scenarios, interactions between mobile network operator (MNO) infrastructures and multi-access edge computing (MEC) systems across international borders are required at both the control and data planes to provide seamless and uninterrupted services to users transitioning between two MNOs. However, the exchange of informatio...

In this manuscript, we present in detail the design and implementation of the hardware and software to produce a standalone wireless sensor node, called SensorQ system, for the detection of a toxic chemical agent. The proposed wireless sensor node prototype is composed of a micro-controller unit (MCU), a radio frequency (RF) transceiver, a dual-ban...

Vehicular mobility underscores the need for collaborative misbehavior detection at the vehicular edge. However, locally trained misbehavior detection models are susceptible to adversarial attacks that aim to deliberately influence learning outcomes. In this paper, we introduce a deep reinforcement learning-based approach that employs transfer learn...

Vehicular mobility underscores the need for collaborative misbehavior detection at the vehicular edge. However, locally trained misbehavior detection models are susceptible to adversarial attacks that aim to deliberately influence learning outcomes. In this paper, we introduce a deep reinforcement learning-based approach that employs transfer learn...

Recent advancements in vehicle-to-everything (V2X) communication have notably improved existing transport systems by enabling increased connectivity and driving autonomy levels. The remarkable benefits of V2X connectivity come inadvertently with challenges which involve security vulnerabilities and breaches. Addressing security concerns is essentia...

Cooperative, Connected and Automated Mobility (CCAM) and Future Railway Mobile Communications System (FRMCS) use cases present strict requirements in terms of service end-to-end latencies, data-rates, reliability and service availability , posing challenges in the design of 5G network architectures for cross-border scenarios, where current roaming...

In this paper, we propose and evaluate two mechanisms aimed at improving the communication reliability of IEEE 802.15.4g SUN (Smart Utility Networks) in industrial scenarios: RTS (Re-Transmission Shaping), which uses acknowledgements to track channel conditions and dynamically adapt the number of re-transmissions per packet, and AMS (Adaptive Modul...

The development of new tools that allow continuous monitoring of air quality is essential for the study of actions, in order to improve the levels of pollutants in the air that are harmful to the health of citizens. Cardiovascular and respiratory diseases have been identified as risk factors for death in patients with COVID-19; at the same time, ex...

Vehicle-to-everything (V2X) communications enable real-time information exchange between vehicles and infrastructure, which extends the perception range of vehicles beyond the limits of on-board sensors and, thus, facilitating the realisation of cooperative, connected, and automated mobility (CCAM) services that will improve road safety and traffic...

The ongoing integration of advanced wireless communication technologies in the automotive sector is expected to radically transform current transport systems into fully automated and inter-connected systems by enabling a large number of interactions among various network entities, e.g., vehicles, road users, roadside infrastructure. The ubiquitous...

Packet re-transmissions are a common technique to improve link reliability in low-power wireless networks. However, since packet re-transmissions increase the end-device energy consumption and the network load, a maximum number of re-transmissions per packet is typically set, also considering the duty-cycle limitations imposed by radio-frequency re...

World cities are currently facing one of the major crisis of the last century. Some preliminary studies on COVID-19 pandemia have shown that air pollutants may have a strong impact on virus effects. Improved gas sensors and wireless communication systems open the door to the design of new air monitoring systems based on citizen science to better mo...

Packet re-transmissions are a common technique to improve link reliability in low-power wireless networks. However, since packet re-transmissions increase the end-device energy consumption and the network load, a maximum number of re-transmissions per packet is typically set, also considering the duty-cycle limitations imposed by radio-frequency re...

This paper models and evaluates three FSA-based (Frame Slotted ALOHA) MAC (Medium Access Control) protocols, namely, FSA-ACK (FSA with ACKnowledgements), FSA-FBP (FSA with FeedBack Packets) and DFSA (Dynamic FSA). The protocols are modeled using an AMC (Absorbing Markov Chain), which allows to derive analytic expressions for the average packet dela...

The vision of cooperative, connected and automated mobility (CCAM) across Europe can only be realized when harmonized solutions that support cross-border traffic exist. The possibility of providing CCAM services along different countries when vehicles drive across various national borders has a huge innovative business potential. However, the seaml...

Even before 5G is rolled out, Mobile Edge Computing (MEC) can be considered as a key driver towards the deployment of vehicular use cases, which pose stringent latency and bandwidth requirements to the underlying Vehicle-to-Everything (V2X) communication infrastructure. In this paper, we present a MEC-enabled cooperative Collision AVoidance (CAV) s...

In this paper we experimentally evaluate and compare the robustness against interference of the OQPSK-DSSS (Offset Quadrature Phase Shift Keying - Direct Sequence Spread Spectrum) and the SUN-OFDM (Smart Utility Network - Orthogonal Frequency Division Multiplexing) physical layers, as defined in the IEEE 802.15.4-2015 standard. The objective of thi...

In this paper, we experimentally evaluate and compare the robustness against interference of the OQPSK-DSSS (Offset Quadrature Phase Shift Keying - Direct Sequence Spread Spectrum) and the SUN-OFDM (Smart Utility Network - Orthogonal Frequency Division Multiplexing) physical layers, as defined in the IEEE 802.15.4-2015 standard. The objective of th...

European cities are currently facing one of the main evolutions of the last fifty years. “Cities for the citizens” is the new leitmotiv of modern societies, and citizens are demanding, among others, a greener environment including non-polluted air. Improved sensors and improved communication systems open the door to the design of new systems based...

Selection of the most appropriate communications technology for a smart grid (SG) application is far from trivial. We propose such a feasibility assessment starting from identification of key performance indicators (KPIs) required for peer-to-peer (P2P) energy trading and grid control operations from a communications perspective. A set of cross-dis...

The Internet of Things (IoT) will facilitate a wide variety of applications in different domains, such as smart cities, smart grids, industrial automation (Industry 4.0), smart driving, assistance of the elderly, and home automation. Billions of heterogeneous smart devices with different application requirements will be connected to the networks an...

Power distribution networks are often widely distributed to accommodate electrical power feeds to dense cities while monitoring and control systems typically require extensive information exchange among numerous intelligent electronic devices. Using the existing network infrastructure, cellular technology appears as a key enabler for the support of...

In this paper, we consider a wireless Machine-to- Machine network composed of end-devices with energy harvesters that periodically transmit data to a gateway. While energy harvesting allows for perpetual operation, the uncertain amount of harvested energy may not guarantee fully continuous operation due to temporary energy shortages. This fact need...

This paper presents, models, and evaluates energy harvesting–aware distributed queuing (EH-DQ), a novel medium access control protocol that combines distributed queuing with energy harvesting (EH) to address data collection applications in industrial scenarios using long-range and low-power wireless communication technologies. We model the medium a...

In this paper, a novel random access mechanism is introduced to enable the integration of smart grid distribution automation (DA) services in public LTE networks. The smart grid paradigm is anticipated to improve grid reliability through extensive and timely information exchange in the power distribution network. LTE appears as a promising communic...

ALOHA-type protocols became a popular solution for distributed and uncoordinated multiple random access in wireless networks. However, such distributed operation of the Medium Access Control (MAC) layer leads to sub-optimal utilization of the shared channel. One of the reasons is the occurrence of collisions when more than one packet is transmitted...

The vision of the Internet of Things (IoT) to interconnect and Internet-connect everyday people, objects, and machines poses new challenges in the design of wireless communication networks. The design of Medium Access Control (MAC) protocols has been traditionally an intense area of research due to their high impact on the overall performance of wi...

The Internet of Things (IoT) will facilitate a wide variety of applications in different domains, such as smart cities, smart grids, industrial automation (Industry 4.0), smart driving, assistance of the elderly, and home automation. Billions of heterogeneous smart devices with different application requirements will be connected to the networks an...

ALOHA-type protocols became a popular solution for distributed and uncoordinated multiple random access in wireless networks. However, such distributed operation of the Medium Access Control (MAC) layer leads to sub-optimal utilization of the shared channel. One of the reasons is the occurrence of collisions when more than one packet is transmitted...

This paper describes an experimental implementation of a variation of the Reverse Direction (RD) Medium Access Control (MAC) Protocol (RDP) defined in the IEEE 802.11n using the Wireless Open-Access Research Platform (WARP). The proposed approach, named Bidirectional MAC (BidMAC), allows the receiver of a valid data sequence to perform an RD transm...

Machine-to-Machine (M2M) area networks aim at connecting an M2M gateway with a large number of energy-constrained devices that must operate autonomously for years. Therefore, attaining high energy efficiency is essential in the deployment of M2M networks. In this paper, we consider a dense M2M area network composed of hundreds or thousands of devic...

One of the main challenges of Machine-to-Machine (M2M) communications is to extend the network lifetime by either using energy efficient communication protocols or by making use of energy harvesting techniques. In this paper, we consider a wireless M2M network composed of a large group of end-devices with energy harvesting capabilities that periodi...

Reservation frame slotted-ALOHA (RFSA) was proposed in the past to manage the access to the wireless channel when devices generate long messages fragmented into small packets. In this paper, we consider an M2M area network composed of end-devices that periodically respond to the requests from a gateway with the transmission of fragmented messages....

Current Medium Access Control (MAC) protocols for data collection scenarios with a large number of nodes that generate bursty traffic are based on Low-Power Listening (LPL) for network synchronization and Frame Slotted ALOHA (FSA) as the channel access mechanism. However, FSA has an efficiency bounded to 36.8% due to contention effects, which reduc...

Data collection is a key scenario for the Internet of Things because it enables gathering sensor data from distributed nodes that use low-power and long-range wireless technologies to communicate in a single-hop approach. In this kind of scenario, the network is composed of one coordinator that covers a particular area and a large number of nodes,...

Energy efficiency is one of the main challenges of Machine-to-Machine (M2M) networks, since they aim at connecting devices with limited access to power sources and operate without human intervention. It has been shown in the past that the use of short-range cooperation between wireless devices equipped with multiple Radio Access Technologies (RATs)...

Machine-to-Machine (M2M) area networks must provide connectivity between an M2M gateway and a large number of energy-constrained M2M devices. Attaining high energy efficiency is essential in order to prolong devices lifetime. In this paper, we consider a wireless M2M area network composed of hundreds or even thousands of dormant devices that wake u...

Recent standardization efforts on low-power wireless communication technologies, including time-slotted channel hopping (TSCH) and DASH7 Alliance Mode (D7AM), are starting to change industrial sensing applications, enabling networks to scale up to thousands of nodes whilst achieving high reliability. Past technologies, such as ZigBee, rooted in IEE...

In this paper, we consider a Machine-to-Machine (M2M) wireless network composed of a group of devices which duty cycle to save energy. These devices operate in low-power sleeping mode for most of the time and, periodically, they wake-up to listen to a poll packet transmitted by a data collector. Upon this broadcast poll, all devices try to get acce...

We propose in this paper a simple method to optimize the duty-cycle of a Machine-to-Machine (M2M) area network equipped with energy harvesters so that the Energy Neutral Operation (ENO) can be achieved and thus devices can operate autonomously forever, as far as the communication part is regarded. We use an exponentially weighted moving-average (EW...

Machine-to-Machine (M2M) area networks connect a gateway with a huge number of energy-constrained end-devices. Therefore, energy efficiency is essential to prolong the lifetime of M2M networks. In this paper, we consider an M2M area network composed of hundreds or thousands of end-devices that periodically transmit data upon request from a gateway....

Machine-to-Machine (M2M) networks must be energy-efficient to operate autonomously for years, or even decades. In this paper, we consider a synchronized duty-cycled M2M network composed of a huge number of dormant devices that periodically wake up to transmit data to a coordinator. We propose the use of Distributed Queuing (DQ) tree-splitting algor...

Data transport fluctuations affecting vehicular connectivity are inexperienced in fixed access as well as in pedestrian mobility: in this paper we review how solutions known as WAN (wide area network) optimizations can be effective to improve user experience in vehicular clients. We show that the core techniques for enabling WAN optimizations are b...

Data transport fluctuations affecting vehicular connectivity are inexperienced in fixed access as well as in pedestrian mobility: in this paper we review how solutions known as WAN (wide area network) optimizations can be effective to improve user experience in vehicular clients. We show that the core techniques for enabling WAN optimizations are b...

Due to propagation and interference effects at the 2.4 GHz band, Machine-to-Machine (M2M) wireless commu-nications based on the IEEE 802.15.4 standard typically need multi-hop communications to connect end devices with a gateway. Unfortunately, multi-hop transmissions pose some challenges that are not trivial to solve and may slow down the deployme...

Emerging Machine-to-Machine (M2M) applications demand small data packet sizes, very low latencies, and ultrahigh energy efficiencies. For all these reasons, Binary Bose-Chaudhuri-Hocquenhem (BCH) codes, which are very simple to implement, could constitute a good option to guarantee the required reliability of M2M transmissions. Nevertheless, existi...

This paper experimentally validates the efficiency of Cooperative Automatic Retransmission reQuest (C-ARQ) versus traditional ARQ protocols in terms of delay, throughput, and energy consumption. We report on our development of a testbed for obtaining these results, which is based on OpenMAC, a platform we have designed for rapid prototyping of MAC...

Attaining very high energy efficiency is one of the big challenges to implement Machine-to-Machine (M2M) networks whose lifetime (without human intervention) must be measured in years. In this paper, we consider a synchronized duty-cycled M2M network composed of a large number of devices that periodically wake up their radio interfaces to transmit...

The design of communications protocols that exploit the availability of both cellular and short-range radio access interfaces in a same terminal can be exploited to improve the energy efficiency of wireless communications networks. Devices equipped with a cellular radio interface can act as dynamic gateways to provide energy-constrained devices in...

Although mobile devices are rapidly developing with new advanced functionalities, the advances in battery lifetime are much slower. In the Green-T project, we address this problem by utilizing multiple radio interfaces in efficient ways in order to optimize the energy consumption. A first step is to use the interface which provides the best energy...

One of the main problem in transmitting coded data is that the decoder does not know the real number of errors to correct. This issue is critical since it means that the decoders spend much more iterations for correcting them. A paradigmatic case of this is the Bose-Chaudhuri-Hocquenghem (BCH) code. This type of code generally resorts to the Berlek...

OpenMAC is presented in this paper as an innovative experimental platform suitable for field testing and performance evaluation of Medium Access Control (MAC) protocols developed in C++. The concept design of OpenMAC avoids the use of hardware-specific code or Hardware Description Language (HDL), softening the learning curve and accelerating the im...

OpenMAC is presented in this study as an innovative reconfigurable platform which overcomes the limitations of state-of-the-art experimental tools to test medium access control (MAC) protocols. The purpose of the OpenMAC platform is to simplify the prototyping process by enabling the implementation of MAC protocols designed in C++, relieving the pr...

The key role played by the medium access control layer toward the performance of wireless communication networks justifies the vast amount of MAC protocols that can be found in the literature. Indeed, most of these works evaluate the performance of the proposals by means of either theoretical analysis or computer-based simulation. Unfortunately, th...