OWC-SP 2022 Abstracts

Area 1 - Optical Wireless Communications: Status and Perspectives
Short Papers

Area 1 - Optical Wireless Communications: Status and Perspectives

Nr: 10
Title:

LiFi Use Cases Tested in Real Environments
Authors:

Christoph Kottke, Dominic Schulz and Volker Jungnickel
Abstract: The amount of wireless data traffic and the number of devices continues to grow at an exponential rate. Over the past decades, we have seen waves of innovation to enhance the bit rates (bit/s) and the density (bit/s/m2) that can be provided by wireless radio networks, but the wireless technology needed to support this also becomes increasingly complex. One can argue that a disruptive change to include optical wireless communications, which is also denoted as LiFi, becomes attractive. Light sources such as light emitting diodes (LEDs) can offer gigabits per second with simple emitters and receivers at very low cost. In this invited talk we present selected use cases for LiFi in the future IoT, which have been tested in real environments, i.e. fixed wireless access (FWA), for indoor positioning and industrial LiFi integrated with 5G. Our goal is to develop a flexible system concept for LiFi to serve a wide diversity of use cases, and show in this way that LiFi is increasingly mature and promising to serve a mass market. The requirements, key features, demonstrator realizations and early results for each selected use case are presented and discussed. The work is conducted in the EU project ELIOT [1]. Fiber-to-the-home (FTTH) deployments allow Gbit/s data rates and robustness but suffer from high installations cost, especially due to digging the fiber. An alternative is the fixed wireless access (FWA), where the last hop to the customer is realized with a wireless link. Instead of connecting each household with a fiber, the fiber will only be deployed at the curb, e.g. the street lights in a residential area, and the final hop to the building is less costly using so called wireless-to-the-home (WTTH) nodes. We showcase an optical wireless link with Gbit/s data rates for fixed wireless access. The installation took place in a courtyard under outdoor conditions and over typical link distances. The performance of the LiFi link is investigated and compared against a 60 GHz radio link, addressing various aspects like the transmission through metal-coated insulation glass. Besides communication, smart manufacturing calls for positioning to facilitate various new Industry 4.0 applications. For example, reliable indoor positioning is necessary for using intelligent transport systems (ITS) that transport parts on pallets from one predefined locations to another. We present a LiFi-based positioning system, utilizing fields from physical layer packets defined in the G.9991 LiFi standard. The installation was done in a factory environment and allows accuracies of a few cm. Key challenges such as sufficient coverage and time synchronisation are discussed, as well as requirements for integration into future LiFi chipsets. The ongoing shop floor digitalization confronts manufacturers with challenges in computer networks. WiFi became a standard for enabling mobile applications in factories, but suffers from adjacent WiFi networks operating in parallel. Consequently, WiFi is a less reliable wireless technology for smart factories and could be complemented by LiFi and 5G. With a combination of the technologies, we aim at improved flexibility, reliability, wider coverage, and higher throughput for fixed and mobile devices in factories. We also demonstrate the use of LiFi as a non-3GPP access technology, connected to the 5G core network and describe our initial test results. [1] https://www.eliot-h2020.eu/
Nr: 24
Title:

Sub-ns High-speed Organic Light Emitting Diodes and Perspectives to Light Communication
Authors:

Alexis A. Fischer, Daan Lenstra, Amani Ouirimi, Nixson Loganathan, Alex C. Chime, Mahmoud Chakaroun, Nihal Munshi, Tony Maindron, Luc Maret and Hani Kanaan
Abstract: The literature reports some experiments on light communication based on organic light emitting diode emitters with data rate up to 1.13GBit/s [1]. We present theoretical and experimental evidences indicating that high-speed OLEDs exhibit dynamical behavior in the sub-nanosecond time scale which opens perspectives for Light Communication not only in the GHz regime but tenfold larger. From the theoretical point of view, we will present an electrical dynamical model and an organic laser diode dynamical models based on rate equations that predict both spontaneous and stimulated emission dynamical behaviors in the sub-ns and picoseconds time scale following electrical pulsed excitation. These model also describe emission of Organic light emitting diodes (OLED). Simulations show that firstly, spontaneous emission with 800ps optical pulses and below are possible. Secondly, above threshold, dynamical optical responses of Alq3 based organic devices predict relaxation oscillations with frequencies from 4GHz to 14GHz [2]. In the experimental section we present both the fabrication aspect of the devices and the measured electrical and optical responses of high-speed OLEDs. Among the fabrication aspect, we describe the design and the fabrication of patented solutions based on coplanar waveguide necessary to provide 50 Ohm characteristic impedance to the high-speed OLED electrodes [3]. We also present the fabrication of distributed feedback (DFB) nanostructures compatible with organic heterostructures as necessary cavity for the development of organic laser diodes. Different type of measurement are presented; firstly we report optical pulses of 1ns, 800ps and down to 400ps in duration emitted by specifically designed High-Speed OLEDs. We present also optical and electrical measurement of 100x100µm2 OLED to 20ns electrical pulses at medium (460A/cm2) and high (8.8kA/cm2) current density [4]. These measurements are fitted with simulations, thus validating the proposed dynamical model and giving credibility that OLED can be as fast as, or even faster than III-V based LEDs. Finally, the combined conclusions from the models and the measurements are twofold, firstly the fabrication and the demonstration of organic laser diode is at hand with cavities and current density large enough to reach the laser threshold, and secondly, we propose a High-Speed-OLED based organic light-communication emitters and with Orthogonal Frequency Division Multiplexing (OFDM) allowing spectral efficiency as high as 8bits/Hz, we project data transmission rate up to 10Gbit/s. [1] K. Yoshida et al., “245 MHz bandwidth organic light-emitting diodes used in a gigabit optical wireless data link,” Nat Commun, vol. 11, no. 1, p. 1171, Dec. 2020, doi: 10.1038/s41467-020-14880-2. [2] D. Lenstra et al. “Ultra-Short Optical Pulse Generation in Micro OLEDs and the Perspective of Lasing", submitted to JOPT-109128 [3] A. C. Chime, et al, “Analysis of Optical and Electrical Responses of µ-OLED With Metallized ITO Coplanar Waveguide Electrodes Submitted to Nanosecond Electrical Pulses,” IEEE Transactions on Electron Devices, vol. 66, no. 5, pp. 2282–2289, May 2019, doi: 10.1109/TED.2019.2905839. [4] A. Ouirimi, et al “Threshold estimation of an organic laser diode using a rate-equation model validated experimentally with a microcavity OLED submitted to nanosecond electrical pulses,” Organic Electronics, vol. 97, p. 106190, Oct. 2021, doi: 10.1016/j.orgel.2021.106190.
Nr: 25
Title:

Standardization Status (LC, 5G & Beyond 5G)
Authors:

Max Riegel
Abstract: Standards are an important prerequisite for mass deployment of communication technologies. As Light Communications span a wide variety of applications, a single standard is not able to serve all potential applications enabling high-performance cost-optimized solutions. A first light communications standard specifying short-range visible light communications (VLC) was initiated in 2008 and ratified in 2011 through IEEE Std 802.15.7-2011. The standard provides three different PHY modes with a common MAC to deliver data rates sufficient to support audio and video multimedia services. It considers mobility of the VLC link, impairments due to noise and interference from sources like ambient light. The specification was later revised to IEEE Std 802.15.7-2018 broadening its applicability to wave lengths in the range 190 nm to 10 000 nm, and adding further 3 PHY modes to fully incorporate Optical Camera Communication (OCC) solutions. Currently, an amendment to 802.15.7 is in development further evolving the specification regarding OCC to address more use cases in particular in the domain of Vehicle-to-everything (V2X) communications, and for various deployments in industrial automation. Parallel to the past and ongoing enhancements to 802.15.7, IEEE initiated P802.15.13 to address high speed light communication needs with up to 10 Gb/s over distances of up to 200m unrestricted line. It leverages latest technologies like distributed MU-MIMO and offers three different PHY modes for data rates of up to 2.2 Gb/s per stream. Ratification is expected for 2022. The IEEE 802.11 working group, the home of Wi-Fi, initiated also efforts to complement Wi-Fi with a LC interface. The project P802.11bb is aimed for the high volume mass market to facilitate the extension of common Wi-Fi deployments with LiFi, when radio communication is not possible or is impacted through exhaustion of the radio spectrum. It vastly leverages the IEEE 802.11ax capabilities and minimizes additional functions to the essential pieces to enable very cost-effective chip implementations for the transmission of the base band signal over light instead of a high frequency radio channel. Completion of the amendment is expected for end of 2022. Aside of IEEE, other global standardization organizations are active in light communications as well. The ITU-T Study Group 15 Question 18 started in 2015 an effort to create a light communication variant of its home networking standard G.hn. G.9991, as the LC standard is denoted, adopts basic architecture, the principal design of the OFDM-based PHY, the DL functions, and the management interface from the G.hn base specifications G.9960 to G.9964. The G.9991 specification, initially released in 2019, incorporates a second PHY mode based on Asymmetrically Clipped Optical OFDM that better adapts to the nature of light. Later amendments released in 2020 and 2021 added port based access control according to IEEE 802.1X, and enhanced mobility support to address the needs of mobile terminals in larger deployments. Current light communication standards already fulfill many of the requirements covered in the 5th generation mobile communication system (5G) and can be leveraged to provide 5G services over light communication. However, further standards developments can be expected to better leverage the capabilities of light communications addressing use cases and requirements that are currently outside of the possibilities of wireless interfaces.
Nr: 28
Title:

Optical Components for Light Communications
Authors:

Markus Bilger
Abstract: Light communication systems rely on optical components for efficiency and optimum signal to noise ratio. Increasingly, these systems rely on NIR VCSEL's as a light source to enable maximum data transmission rates. There are two critical optical components in optical system we will concentrate on in this presentation. 1. On the transmitting side of the device, we need a feature which evenly distributes the light from the VCSEL or VCSEL array over a large angle range. A preferred way to do this by using a diffuser which creates a uniform intensity distribution. These diffusers are based on randomly arranged micro lenses which transmit the light. Alternative technologies based on diffractive optics have the disadvantage that they have zero order effects, which can result in non-uniform intensity distributions, especially at the straight-forward (zero order) direction. This limits the emitted power allowed due to eye safety concerns. We will present a technology which enables customizable solutions, to improve overall system performance. 2. On the receiving side of the device, the detector must be capable to detect a low-level signal from the light source (VCSEL) with high intensity ambient light present. This will require a narrow band optical filter to achieve high signal to noise ratio. Optical interference filters inherently have the undesired property, that their spectral performance will shift to lower wavelength when the angle of incidence is increased, therefore, to capture light from a large field of view the width of the filter pass band needs to broaden. We will introduce a patented technology to light communication application which enables to cut the angle shift by one third versus the ‘standard’ technology and thus significantly reduces the bandwidth required of the filter thus increasing the signal to noise ratio of the system.
Nr: 31
Title:

Integration of VLC in Future 5G Advanced/ 6G Networks.
Authors:

Lars Dittmann
Abstract: This paper shows how Visible Light Communication (VLC) is integrated as a flexible resource for 5G advanced systems. VLC does in many ways resemble the coming extension of 5G into the domain of using 26 GHz – and higher frequencies. Both link systems provide significant high capacity, that will be of high demand in supporting the needs for eMBB access systems. Both systems requires Line-Of-Sight and in many cases mainly provide unidirectional communications capabilities. On the other hand, they differ in transceiver architecture. Where millimeter wave links requires new and more sophisticated antenna systems (massive MIMO’s) for beam forming and steering, the use of VLS can much easier be integrated into existing lightening system e.g. in office building, streetlight, vehicle lightening systems (car, trains and even bicycles). Simple and cheap sensors/cameras that are standard in not only smartphones and tables can act as receivers. While the similarities of VLC and millimeter wave communication can ease the integration of VLC as a resource in 5G advanced – the much simpler transceiver structure can also open up for more extensive use of VLC future in smart cities and smart transport. In this paper, an architectural framework for inclusion of VLC technology in an enhanced 5G network will be presented. The architecture is using Software Defined Networking solution as a tool to incorporate the resources of different physical layer technologies and especially the ability to efficiently use unidirectional link as a capacity booster. The paper will primarily focus on the control plane architecture that can be used in a multi-technology RAN network. This is handled by taking into account, how the individual characteristic of various link technology can be used the most efficient. Not only traditional device to infrastructure links will be explored, but a special focus will be on how D2D (Device2Device) solutions can minimize latency and expand coverage enabling ad-hoc networking. The applications in focus in this paper are within intelligent transport in urban areas and includes both trains, busses and car. The paper will also present some early ideas on how VLC can be used by bicycles – especially the fast expanding market for electrical bicycles. The work presented will include ideas from the EU projects SHOW (GRANT No 875530) and the 5G-PPP project 5GRAIL (GRANT No 951725).
Nr: 32
Title:

LiFi/Wi-Fi based Heterogenous WLANs: Discovering the Best Associations between Stations and Access Points
Authors:

Thomas Begin, Esther Guérin, Anthony Busson and Isabelle G. Lassous
Abstract: We investigate how much an adequate association between stations and access points in LiFi/Wi-Fi based heterogeneous WLANs can help in terms of the QoS of stations as well as the overall energy consumption. We propose a strategy based on the use of performance and energy models to discover efficient associations. Our results show that heterogeneous WLANs, if configured properly, can represent an effective solution.
Nr: 33
Title:

Non-point Light Localization in Dynamic Environment using Deep Learning
Authors:

Hongxiu Zhao, Wafa Njima, Xun Zhang and Faouzi Bader
Abstract: Among many visible light positioning (VLP) methods, the use of monocular camera is much potential because of its low cost and high-speed calculation [1]. When there is any change in the environment (e.g. chair moving, pedestrian walking, changement on the number of targets, etc.) different non line of sight (NLOS) channels are deduced. In such dynamic environments, lighting occlusions will be caused and cameras cannot picture the overall transmitter due to the NLOS channels, which deduced difficulties of images processing. In this case, deep learning (DL) approaches have reported state-of-the-art results for most of the challenging tasks in images processing area [2]. Meanwhile, existing VLP methods mostly focus on point-light or regular shaped light, which is not advisable in the complex and dynamic environment [3]. Under the circumstance of non-point light transmitter, a new model could be established using a set of evenly distributed points, which supplies many mapping points in the camera. Therefore, in this paper, we will use conventional neural networks (CNN) and deep neural networks (DNN) based methods to deal with the images captured by the monocular camera deploying only one non-point light even though the shadow. In the process of monocular camera positioning, perspective from 3 points (P3P) are required to refine the initial estimated localization based on all pictures received from detected LEDs. Overall, the proposed algorithm involves three steps: (i) model the transmitters, (ii) calculate initial location estimation using monocular camera and (iii) optimize the estimated location using deep learning methods.
Nr: 35
Title:

Signify's Perspective on LiFi and Use Cases
Authors:

Musa Unmehopa
Abstract: In this presentation we will provide a review of LiFi use cases and applications, both present as well as forward looking, across a number of market segments. We will provide the perspective of Signify, but also the broader perspective of the lighting industry as a whole. We will present a comprehensive ecosystem approach towards collectively enabling and growing the global market for optical wireless communication technologies, with an emphasis on multi-vendor interoperability through standards-based certification programs.
Nr: 53
Title:

Light Communication. Alliance Presentation
Authors:

Marc Fleschen
Abstract: Light communication alliance is a non profit organisation established in Luxembourg in 2019. Mission driving a consistent focused and concise approach to market education that will highlight the benefits and uses cases of light communications
Short Papers
Paper Nr: 2
Title:

Towards Terabit LiFi Networking
Authors:

Ahmad A. Qidan, Taisir El-Gorashi and Jaafar H. Elmirghani
Abstract: Light Fidelity (Li-Fi) is a networked version of optical wireless communication (OWC), which is a strong candidate to fulfill the unprecedented increase in user-traffic expected in the near future. In OWC, a high number of optical access points (APs) is usually deployed on the ceiling of an indoor environment to serve multiple users with different demands. Despite the high data rates of OWC networks, due to the use of the optical band for data transmission, they cannot replace current radio frequency (RF) wireless networks where OWC has several issues including the small converge area of an optical AP, the lack of uplink transmission and high blockage probabilities. However, OWC has the potential to support the requirements in the next generation (6G) of wireless communications. In this context, heterogeneous optical/RF networks can be considered to overcome the limitations of OWC and RF systems, while providing a high quality of service in terms of achievable data rates and coverage. In this work, infrared lasers, vertical-cavity surface-emitting(VCSEL) lasers, are used as the key elements of optical APs for serving multiple users. Then, transmission schemes such as zero forcing (ZF) and blind interference alignment (BIA) are introduced to manage multi-user interference and maximize the sum rate of users. Moreover, a WiFi system is considered to provide uplink transmission and serve users that experience a low signal to noise ratio (SNR) from the optical system. To use the resources of the heterogeneous optical/RF network efficiently, we derive a utility-based objective function that aims to maximize the overall sum rate of the network. This complex problem can be solved using distributed algorithms to provide sub-optimal solutions with low complexity. The results show that the sum rate of the proposed hybrid network is higher than the standalone optical network, using different transmission schemes.
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Paper Nr: 7
Title:

All Signs Lead to LiFi
Authors:

Alistair Banham, Sarah Scace, Ron Schaeffer and Mostafa Afgani
Abstract: All signs lead to LiFi. Global communications requirements for greater bandwidth, reliable communications, ultra-high speeds and unprecedented security can only be delivered by introducing LiFi to the communications mix. Using light instead of radio waves to send and receive data, LiFi’s security, safety and bandwidth advantages make it the right solution at the right time.
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