Introduction to indoor networking concepts and challenges in LiFi

LiFi is networked, bidirectional wireless communication with light. It is used to connect fixed and mobile devices at very high data rates by harnessing the visible light and infrared spectrum. Combined, these spectral resources are 2600 times larger than the entire radio frequency (RF) spectrum. This paper provides the motivation behind why LiFi is a very timely technology, especially for 6th generation (6G) cellular communications. It discusses and reviews essential networking technologies, such as interference mitigation and hybrid LiFi/Wi-Fi networking topologies. We also consider the seamless integration of LiFi into existing wireless networks to form heterogeneous networks across the optical and RF domains and discuss implications and solutions in terms of load balancing. Finally, we provide the results of a real-world hybrid LiFi/Wi-Fi network deployment in a software defined networking testbed. In addition, results from a LiFi deployment in a school classroom are provided, which show that Wi-Fi network performance can be improved significantly by offloading traffic to the LiFi

Load balancing in hybrid LiFi and RF networks

The increasing number of mobile devices challenges the current radio frequency (RF) networks. The conventional RF spectrum for wireless communications is saturating, motivating to develop other unexplored frequency bands. Light Fidelity (LiFi) which uses more than 300 THz of the visible light spectrum for high-speed wireless communications, is considered a promising complementary technology to its RF counterpart. LiFi enables daily lighting infrastructures, i.e. light emitting diode (LED) lamps to realise data transmission, and maintains the lighting functionality at the same time. Since LiFi mainly relies on line-of-sight (LoS) transmission, users in indoor environments may experience blockages which significantly affects users’ quality of service (QoS). Therefore, hybrid LiFi and RF networks (HLRNs) where LiFi supports high data rate transmission and RF offers reliable connectivity, can provide a potential solution to future indoor wireless communications. In HLRNs, efficient load balancing (LB) schemes are critical in improving the traffic performance and network utilisation. In this thesis, the optimisation-based scheme (OBS) and the evolutionary game theory (EGT) based scheme (EGTBS) are proposed for load balancing in HLRNs. Specifically, in OBS, two algorithms, the joint optimisation algorithm (JOA) and the separate optimisation algorithm (SOA) are proposed. Analysis and simulation results show that JOA can achieve the optimal performance in terms of user data rate while requiring high computational complexity. SOA reduces the computational complexity but achieves low user data rates. EGTBS is able to achieve a better performance/complexity trade-off than OBS and other conventional load balancing schemes. In addition, the effects of handover, blockages, orientation of LiFi receivers, and user data rate requirement on the throughput of HLRNs are investigated. Moreover, the packet latency in HLRNs is also studied in this thesis. The notion of LiFi service ratio is introduced, defined as the proportion of users served by LiFi in HLRNs. The optimal LiFi service ratio to minimise system delay is mathematically derived and a low-complexity packet flow assignment scheme based on this optimum ratio is proposed. Simulation results show that the theoretical optimum of the LiFi service ratio is very close to the practical solution. Also, the proposed packet flow assignment scheme can reduce at most 90% of packet delay compared to the conventional load balancing schemes at reduced computational complexity

Communications par Lumière Visible et Radio pour la Conduite Coopéraive Autonome: application à la conduite en convois.

By realizing both low-cost implementationand dual functionality, VLC has becomean outstanding intriguing supportivetechnology by using the vehicular existedinfrastructure.This thesis aims to contribute to theautonomous vehicular communicationand urban mobility improvements. Thework addresses the main radio-basedV2V communication limitations and challengesfor ITS hard-safety applicationsand intends to deploy the vehicular lightingsystem as a supportive communicationsolution for platooning of IVCenabledautonomous vehicles. The ultimateobjectives of this Ph.D. researchare to integrate the VLC system withinthe existing C-ITS architecture by developinga VLC prototype, together withsufficient hand-over algorithms enablingVLC, RF, and perception-based solutionsin order to ensure the maximumsafety requirements and the continuousinformation exchange between vehicles.The feasibility and efficiency of thesystem implementation and hand-overalgorithms were subjects to deep investigationsusing computer simulators andtest-bed that considers applications ofautomated driving. In addition to the improvementin road capacity when platoonformations are used. The carried outsimulations followed-up by experimentalresults proved that the integration of VLCwith the existed RF solutions lead to adefinite benefit in the communicationchannel quality and safety requirementsof a platooning system when a properhand-over algorithm is used.La communication par lumière visibleVLC est devenue une technologie attractivevu qu’elle assure une implémentationà faible coût et une doublefonctionnalité. En effet, elle permetd’utiliser l’infrastructure déjà existantesur le véhicule à savoir les lampesd’arrière et frontales comme des unitésde transmission. Cette thèse s’intéresseà rendre plus efficace les communicationsdes véhicules autonomes ainsi quela gestion de la mobilité urbaine. Nousnous intéressons tout d’abord aux principaleslimitations des communicationsradio sans fil dans le contexte des applicationsde sécurité routière à hautes exigences.Nous nous concentrons ensuiteau déploiement d’un système d’éclairagesur les véhicules dans le but de fournir unmoyen de communication de soutien auxcommunications radio pour l’applicationde peloton. L’objectif primordial decette thèse est d’intégrer la technologieVLC dans l’architecture de communicationITS en implémentant un prototypede communication VLC et en concevantde nouveaux algorithmes de handoverpermettant une transition transparenteentre différents moyens de communicationinter-véhiculaires (VLC, communicationsans fil et techniques de perception).Le but est d’assurer les exigencesde sécurité requises par les applicationset l’échange continue de l’informationentre véhicules. L’efficacité de ces algorithmesa été validée à travers de nombreusessimulations et test-bed réels aucours desquels nous avons considérél’application de conduite automatisée.Ces différentes méthodes de validationont démontré que l’intégration de la technologieVLC avec les solutions de communicationsradio permet d’améliorer laqualité du canal de transmission ainsique la satisfaction des exigences de sécuritérelatives à l’application de peloton

Advanced Trends in Wireless Communications

Physical limitations on wireless communication channels impose huge challenges to reliable communication. Bandwidth limitations, propagation loss, noise and interference make the wireless channel a narrow pipe that does not readily accommodate rapid flow of data. Thus, researches aim to design systems that are suitable to operate in such channels, in order to have high performance quality of service. Also, the mobility of the communication systems requires further investigations to reduce the complexity and the power consumption of the receiver. This book aims to provide highlights of the current research in the field of wireless communications. The subjects discussed are very valuable to communication researchers rather than researchers in the wireless related areas. The book chapters cover a wide range of wireless communication topics