Browsing by Author "Refas, Souad"

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Canaux et architecture pour les communications en lumière visible
(Université M'hamed Bougara Boumerdès : Faculté de Technologie, 2020) Morsi, Noudjoud; Refas, Souad; Ghanem, Khalida(Promoteur)
Ce Travail commençe par une introduction aux communications par lumière visible.Ensuite, une revue des bases de la photométrie est exploitée pour établir ultérieurement les modèles des canaux des systèmes VLC,ainsi que les caractéristiques des émetteurs et des récepteurs de ces systèmes.Diverses techniques de modulation bien adaptées aux VLCs seront subséquemment introduites.Enfin, la dernière section présentera les résultats de simulation relative au canal VLC dans le cas d'un scénario en visibilité directe (LOS) et de celui de non-visibilité (NLOS),ainsi que ceux portant sur les techniques de modulation pouvant être utilisées dans les systèmes de communication par lumière visible
Energy harvesting based on SLIPT in I2V-VLC system
(IEEE, 2023) Refas, Souad; Acheli, Dalila; Yahia, Selma; Meraihi, Yassine
Vehicular connectivity is mostly based on wireless access. The vehicular applications may be limited due to the limited battery life of the equipment involved. To address this issue, a method based on simultaneous light wave information and power transfer (SLIPT) is proposed for harvesting the energy in the Infrastructure-to-Vehicle Visible Light Communication (I2VVLC) system. The purpose of SLIPT is to harvest energy using light sources while decoding information. This article studies the effect of SLIPT in an I2V-VLC system. In this method, the received light from the traffic light source at the vehicle is harvested while decoding the information signal. First, for I2VVLC channel modeling, a recent realistic channel model using the ray-tracing method is utilized. Then, we propose the energy harvesting analysis based on the SLIPT strategy. After that, we investigate the impact of both the longitudinal and lateral distance between the vehicle and the traffic light on the amount of harvested energy. Furthermore, we investigate the relationship between the achievable information rate and the harvested energy amount. The obtained results demonstrate the significant impact of the communication distance and the required information rate on the quantity of harvested energy
A hybrid whale optimization algorithm with tabu search algorithm for resource allocation in indoor VLC systems
(Elsevier, 2023) Yahia, Selma; Meraihi, Yassine; Mirjalili, Seyedali; Taleb, Sylia Mekhmoukh; Refas, Souad; Ramdane-Cherif, Amar; Eldeeb, Hossien B.
This paper proposes a novel hybrid approach (WOATS) based on the hybridization of Whale Optimization Algorithm (WOA) with Tabu search Algorithm (TS) for solving the resource allocation problem for indoor multi-user downlink VLC systems. The efficiency of the proposed WOATS is validated in several scenarios under different settings, considering the throughput and fairness parameters. The results demonstrated that WOATS provides competitive performance in optimizing resource allocation in indoor VLC systems compared to WOA, TS, Particle Swarm Optimization (PSO), Genetic Algorithm (GA), Arithmetic Optimization Algorithm (AOA), Moth Flame Optimization (MFO), Grey Wolf Optimizer (GWO), and Sine Cosine Algorithm (SCA).
Manta ray foraging optimization algorithm for solving the LEDs placement problem in indoor VLC systems
(IEEE, 2022) Yahia, Selma; Meraihi, Yassine; Sadeki, Nesrine; Tellache, Mohamed; Mekhmoukh Taleb, Sylia; Refas, Souad; Benmessaoud Gabis, Asma
Visible light communication is an excellent alternative to traditional Radio Frequency (RF) technology where many problems have been detected including saturation of the RF spectrum, making wireless communication unable to support the high demand of wireless connections. VLC allows communication between users using Light Emitting Diodes (LEDs) as transmitters and Photo-detectors (PDs) as receivers. The deployment of LEDs in indoor VLC Systems is an important issue that affects the coverage of the network. In this paper, we applied the Manta Rays Foraging Optimization (MRFO) algorithm for tackling the LEDs placement problem in indoor VLC systems. We formulate an optimization problem with the goal of maximizing coverage, throughput while ensuring the network requirements. The performance of MRFO was validated in terms of user coverage and throughput compared to Whale Optimization Algorithm (WOA), Bat Algorithm (BAT), and Particle Swarm Optimization (PSO). The simulation results demonstrated that MRFO is more effective than WOA, BAT, and PSO in determining optimal placement of LEDs
Performance analysis of bidirectional multi-hop vehicle-to-vehicle visible light communication
(Institute of Electrical and Electronics Engineers Inc, 2023) Refas, Souad; Acheli, Dalila; Yahia, Selma; Meraihi, Yassine; Ramdane-Cherif, Amar; Van, Nhan Vo; Ho, Tu Dac
Vehicular visible light communication (VVLC) has emerged as a promising field of research, garnering considerable attention from scientists and researchers. VVLC offers a potential solution to enable connectivity and communication between travelling vehicles along the road by using their existing headlights (HLs) and taillights (TLs) as wireless transmitters and integrating photodetectors (PDs) within the car front or car-back as wireless receivers. However, VVLC encounters more challenges than indoor VLC, particularly in vehicle-to-vehicle (V2V) communication, where vehicle mobility disrupts the establishment of direct communication links. To address this, we propose a multi-hop relay system wherein intermediate vehicles act as wireless relays to maintain a line-of-sight (LoS) link. In this paper, we investigate the performance of a bidirectional multi-hop relay V2V-VLC system that operates in both the forward and backward directions. Based on realistic ray tracing channel models, we derive a closed-form expression for the full bidirectional communication range. We also analyze how the transceiver's parameters and the number of relays affect the system performance. Our results show that the proposed bidirectional multi-hop relay system can extend the direct transmission range by more than 19 m with only a hop relay.
Performance study and analysis of MIMO visible light communication-based V2V systems
(Springer, 2022) Yahia, Selma; Meraihi, Yassine; Refas, Souad; Benmessaoud Gabis, Asma; Ramdane-Cherif, Amar; Eldeeb, Hossien B.
Vehicular Visible Light Communication (VLC) has recently attracted much interest from researchers and scientists. This technology enables the connectivity between the vehicles and the infrastructures along the road utilizing the Lighting-Emitting-Diodes based vehicle HeadLights (HLs) and TailLights (TLs) as wireless transmitters. This paper investigates the performance of a Vehicle-to-Vehicle VLC system using a Multiple-Input Multiple-Output (MIMO) scheme. Specifically, we establish the MIMO transmission system by using the two HLs of the source vehicle as wireless transmitters and multiple receivers (RXs) installed at the rear of the destination vehicle as wireless receivers. We consider different numbers of RXs, which result in various MIMO configurations, i.e., 2 × 2 , 2 × 3 , and 2 × 4. We conduct a channel modeling study based on the non-sequential ray-tracing capabilities of the OpticStudio software to obtain the optical channel gain, considering the possibility of both horizontal and vertical displacement between vehicles. We then explore the contribution of each RX in the total received power. In addition, we investigate the effect of weather conditions, modulation orders, and artificial light sources on the bit error rate (BER) performance of the considered MIMO configurations. The obtained results demonstrate that deploying the MIMO with higher orders can significantly enhance the system performance, particularly when there is a lateral shift between the two cars. It has been drawn from our results that the required SNR to achieve a BER of 10- 4 reduces by 6 dB when 2 × 4 MIMO configuration is deployed compared to the 2 × 2 MIMO configuration
Visible light communication-based wireless technology for vehicular communications
(Université M'Hamed Bougara Boumerdès : Faculté de Technologie, 2024) Refas, Souad; Acheli, Dalila(Directeur de thèse)
The recent experimental efforts have demonstrated the feasibility of visible light com- munication (VLC) technology in the intelligent transportation systems (ITS). Vehicular VLC is based on the idea of modulating the light intensity of the light emitting-diodes (LEDs) to transmit information and enables the dual use of exterior automotive and road- side infrastructure lighting for both illumination and communication purposes. However, vehicular VLC technology is still new, which requires further research efforts in many respects. As an example, most works which focus on the modeling of VLC channels are built on the characteristics of the indoor environment. For the vehicular communication, special attention should be devoted to the vehicular mobility, vehicular intensity profile characteristics, as well as to the outdoor atmospheric weather conditions. A new key concept to enable efficient connectivity in vehicular VLC is that the intermediate vehicles can act as relay nodes to receive the signal from the source vehicle and re-transmit it to the destination one. Since the vehicular connectivity is mainly based on the wireless access, the vehicular applications might be limited by the finite battery capacity of the involved devices. This prompts another new key concept named by energy harvesting (EH) systems, which refers to harnessing energy from the environment or other sources and converting it to electrical energy. Thus, the lifetime of energy-constrained vehicular wireless networks can be prolonged, which also offers a promising solution for energy- sustainability of wireless relay nodes. Additionally, Physical layer security (PLS), and Reconfigurable intelligent surfaces (RIS) play a vital role in enhancing the security and reliability of V-VLC systems. Therefore, the overall operational expenses will be reduced. The objective of this study is then investigating the performance of the vehicular VLC systems and giving insight on how the connectivity can be maintained in different vehic- ular scenarios. The impact of enabling the EH systems in the connected vehicles will be further addressed.