Luís Nero Alves

University of Aveiro | UA · Department of Electronics, Telecommunications and Informatics

Trade of between different parameters in Optical Wireless Communications. The presentation would be of use to MSc and PhD students working in this area...

First publications from OWIN6G project...

Optical Wireless Communication (OWC), has beenproposed as a potential technology for applications where thelegacy radio frequency communication may not be suitable orcannot provide the required quality-of-service or security. TheOWC has proven its dominance in a wide range of applica-tions where demand for cost-effectiveness, high bandwidth, andrel...

Dear All, The last meeting and workshop of NEWFOCUS. It has been a very interesting and productive journey. The community is growing and becoming stronger. Thank you all for your support and contributions. Keep up the good work, and look forward to our future collaboration! Regards, Fary, Ali, Xiaodan, Stan and All

Dear All, The final programme for CSNDSP 2024 is now available at the CSNDSP website. Thank you,

This paper presents a novel blur restoration technique specialized for smartphone-to-camera based communication (screen to camera, S2C) system. The key technique is to avoid the repeated scanning of the transmitted data and to lower the amount of data discarded at the receiver end of the S2C system. This image processing method will improve the sys...

The synchronization of symbols in Optical Camera Communication (OCC) is crucial for systems in both global and rolling shutter operations. Global shutter OCC systems sample the received data using a frame acquisition mechanism that presents particularly high jitter while rolling shutter OCC systems are based on a line acquisition mechanism that is...

Dear All, The Final White Paper on Optical Wireless Communication Technologies is now available on the NEWFOCUS Website. Thank you, Stan, Fary and Ali

The 9th biennial colloquium on optical wireless communications (OWC) provides one of the biggest forum for researchers, product and system engineers and systems developers to present and discuss their latest research results in the field of OWC. Please submit your papers and looking forward to discuss your new research results from OWC in Rome ;)

Dear All, 1st Call for Paper - CSNDSP2024 Thank you

The first two White Papers were on the use of OWC as an enabling technology (i) in a range of areas outlined in HE's Pillar II; and (ii) for medium-and long-range links in terrestrial, space-to-ground and ground-to-space, inter-satellite, and underwater communications. The focus of this final White Paper on Optical Wireless Communication will be on...

Dear All, OWIN6G project has just started...

An algorithm for recovering transmitted static identifiers (IDs) in rolling shutter based Optical Camera Communication systems is proposed by the authors, considering a system comprised of a camera and a circular light source. The goal is to allow the correct decoding when the ID frame is only partially detected in the image. A baseline algorithm a...

This article investigates the use of a visible light positioning system in an indoor environment to provide a three dimensional (3D) high‐accuracy solution. The proposed system leveraged the use of a single light‐emitting diode and an image sensor at the transmitter and the receiver (Rx) respectively. The proposed system can retrieve the 3D coordin...

The technical feasibility of developing an Internet of Things multi‐user communication system is evaluated based on a central digital multiband carrierless amplitude and phase transmitter, which broadcasts data on multiple channels for a number of low‐cost/low‐power devices. It addresses the issue of carrier synchronisation, which is critical in re...

Dear All The PhD positions are now open to apply. Looking forward to receiving your applications. Thank you, Stan

Dear All It gives us great pleasure to announce the successful outcome of our research proposal submission to Horizon Europe. OWIN6G has been ranked among the top 5% of proposals out of 900 that were submitted. We will shortly be advertising for 10 fully funded Early Career Researchers (i.e., PhDs) to start work on 1 September 2023. So watch this s...

Temperature is a dynamic variable in most electronic devices. As the device operates, it generates heat, which translates in a temperature increase. Available models commonly disregard these variations due to the fact that they manifest at very large time scales. However, temperature dynamic effects have profound implications on the device model an...

The transfer of health monitoring data from multiple patients using wireless body-area networks requires the use of robust, and energy and bandwidth efficient multiple-access schemes. This paper considers the frequency-division multiple access for the wireless uplink to a fixed access point when using infrared signals to collect medical data from s...

Wireless sensor networks (WSNs) are currently being deployed in everyday objects to collect and transmit information related to humidity, temperature, heartbeat, motion, etc. Such networks are part of the massive machine-type communication (mMTC) scenario within the fifth/sixth generation of wireless networks. In this paper, we consider the optimiz...

The EU COST Action NEWFOCUS is focused on investigating radical solutions with the potential to impact the design of future wireless networks. It aims to address some of the challenges in OWC and establish it as an efficient technology that can satisfy the demanding requirements of backhaul and access network levels in 5G networks. This also includ...

Cooperative communication is a technique that is employed in the context of visible light communications (VLC) to improve data rate, reach, coverage area and multi-user capacity of installed systems. In this work, we assess the performance of cooperative links with an experimental setup arranged in three configurations, where the position of source...

Dedicated software defined testbeds for communication systems performance evaluation presents many advantages over using standard laboratory equipment, providing high re-configurability and custom features design. This paper presents an FPGA-based implementation for visible light communications (VLC) systems with multiband carrierless amplitude and...

Despite being efficient devices, when compared to other light sources, high power light emitting diodes (LEDs) suffer from heating effects that have a negative impact on their reliability. Power LEDs are typically assembled on metal core printed circuit boards (MCPCBs) to facilitate the extraction of the heat. Diamond boards can also be used for th...

With an emphasis on the real-time implementation of a practical carrier-less amplitude and phase (CAP) receiver for visible light communication (VLC), this paper proposes a full-digital architecture for the M-CAP receiver with synchronisation and adaptive blind equalisation. The architecture is mainly based on the observation that a CAP signal can...

In this paper, we study the design aspects of an indoor visible light positioning (VLP) system that uses an artificial neural network (ANN) for positioning estimation by considering a multipath channel. Previous results usually rely on the simplistic line of sight model with limited validity. The study considers the influence of noise as a performa...

O período entre 2018 e 2022 mostrou-nos que o problema dos incêndios à escala global não está a diminuir, antes pelo contrário. Parece que as consequências das alterações climáticas já estão a afectar a ocorrência de incêndios florestais em várias partes do Mundo, de uma forma que só esperaríamos que acontecesse vários anos mais tarde. Em muitos pa...

We analyze the performance of a hybrid visible-light/infrared optical wireless communications network for indoor Internet-of-Things applications. This approach can be used to connect multiple battery-powered sensor nodes using low-cost infrared light emitting diodes to transmit data to a master node located on the ceiling of a room. The master node...

Dear All, we have lost an excellent researcher, a fantastic colleague, a great friend and a wonderfull person :( Fary, Stan, Luis, Ali, Rafa, Erich, Rolando, Michael, Wai Pang and all other colleagues and friends

In this work, a new indoor visible light positioning algorithm is proposed based on support vector machines (SVM) and polynomial regression. Two different multipath environments of an empty room and a furnished room are considered. The algorithm starts by addressing the received power distance relation, considering polynomial regression models fitt...

High power light emitting diodes (LEDs) suffer from heating effects that have a detrimental impact on the devices characteristics. The use of LED carriers with high thermal conductivity promotes the extraction of heat away from the LED junction. Different materials can be used for this purpose, such as alumina, aluminium nitride, and silicon. Diamo...

This paper considers the use of infrared-based optical wireless communications for multi-user uplink wireless body-area networks. We propose the use of optical-orthogonal frequency division multiple access (O-OFDMA) signaling to manage the multiple access (MA) requirement for relatively high-rate medical applications. In particular, we consider asy...

An equivalent circuit model for a typical commercial light-emitting diode (LED) used in visible light communication (VLC) applications is proposed. The parameters of the elements in the model are extracted from the measured impedance using a vector network analyser. The model shows high accuracy in fitting the measured results and shows the effect...

High power light emitting diodes (LEDs) suffer from heating effects that have a detrimental impact on the devices characteristics. The use LED carriers with high thermal conductivity promotes the extraction of heat away from the LED junction. Different materials can be used for this purpose, such as alumina, aluminium nitride, and silicon. Diamond...

The next generation wireless technology networks and beyond (i [...]

This paper present simulation-based results on the impact of transmitter (Tx) position and orientation uncertainty on the accuracy of the visible light positioning (VLP) system based on the received signal strength (RSS). There are several constraining factors for RSS-based algorithms, particularly due to multipath channel characteristics and set-u...

In this paper, we propose and validate an artificial neural network-based equalizer for the constant power 4-level pulse amplitude modulation in an optical camera communications system. We introduce new terminology to measure the quality of the communications link in terms of the number of row pixels per symbol N pps , which allows a fair compariso...

This paper presents a multi-user Visible Light Communication (VLC)-based Internet of Things (IoT) system using multi band-Carrierless Amplitude and Phase (m-CAP) modulation for IoT applications. The proposed system uses a digital m-CAP modulator embedded in a ceiling LED light fixture and analog receivers, aiming at low-cost, low-power, and small-s...

This paper proposes a reconfigurable RF architecture to cope with radar applications in autonomous driving vehicles and the next generation of communications (5G). A radio front-end architecture operating at frequencies between 24 and 27.5 GHz to deliver a small form-factor design that could easily be changed and ease future improvements, has been...

The accuracy of the received signal strength-based visible light positioning (VLP) system in indoor applications is constrained by the tilt angles of transmitters (Txs) and receivers as well as multipath reflections. In this paper, for the first time, we show that tilting the Tx can be beneficial in VLP systems considering both line of sight (LoS)...

This paper presents simulation-based results of the impact of transmitter (Tx) position uncertainty on the accuracy of the received signal strength (RSS)-based visible light positioning (VLP) system considering multipath reflections. RSS-based algorithms are constrained by several factors, most notably due to multipath channel characteristics and s...

This paper describes a vehicle-to-vehicle (V2V) communication system, employing optical camera communications (OCC). The system comprises the light emitting diode (LED)-based taillights and a raspberry camera used as the transmitter (Tx) and the receiver (Rx), respectively. The sectorized taillights (i.e., Tx) are intensity modulated at different f...

The operating temperature plays a key role in the performance and lifetime of photonic integrated circuits (PICs). Miniaturization and increasing heat dissipation promote thermal crosstalk effects and pose additional challenges to the PIC designer. The European Photonics Industry Consortium recommends thermal modeling during design phase. However,...

This paper reports the architecture of an all-digital Swept Time-Delay Cross-Correlator (STDCC) baseband. Until recently, the sliding correlator technique has been mainly employed for sounding the radio propagation channel. However, recent benchmarks have shown promising results in target detection context when compared to commercially available so...

In this paper, for the first time, we propose and validate a nonlinear artificial neural network (ANN) equalizer for constant power pulse amplitude modulation (CP 4-PAM) in an optical camera communication (OCC) system. Using the proposed equalizer, we demonstrate experimental-based non-flickering transmission at a data rate of up to 7 kbps using a...

Future IoT systems will require progressively smaller sizes, cost, complexity and power consumption. This paper proposes a new architecture using a hybrid m-CAP/QAM system with the goal to provide such features to future VLC based IoT devices. The proposed system architecture uses a ceiling LED light fixture implementing an m-CAP digital modulator,...

This paper presents a new analog polynomial pre-distortion circuit using 350nm CMOS technology to reduce the distortion of the power amplifier in wireless communication systems. The proposed pre-distortion circuit uses the polynomial approach. The coefficients of the polynomial are controlled by multiplying them with sufficient digit defined throug...

In optical camera communication (OCC) systems leverage on the use of commercial off-the-shelf image sensors to perceive the spatial and temporal variation of light intensity to enable data transmission. However, the transmission data rate is mainly limited by the exposure time and the frame rate of the camera. In addition, the camera’s sampling wil...