Coherent optical binary polarisation shift keying heterodyne system in the free-space optical turbulence channel

In this paper, analytical and simulation results for the bit error rate (BER) performance and fading penalty of a coherent optical binary polarization shift keying (2PolSK) heterodyne system adopted for a free space optical (FSO) communication link modeled as the log-normal and the negative exponential atmospheric turbulence channels are presented. The conditional and unconditional BER expressions are derived, demonstrating the comprehensive similarity between the 2PolSK and the binary frequency shift keying (2FSK) schemes with regards to the system sensitivity. The power penalty due to the non-ideal polarization beam splitter (PBS) is also analyzed. The receiver sensitivity employing 2PolSK is compared with other modulation schemes in the presence of turbulence and the phase noise. The results show that 2PolSK offers improved signal-to-noise ratio (SNR) performance compared to the binary amplitude shift keying (2ASK)

European H2020 Project WORTECS Wireless Mixed Reality Prototyping

This paper presents European collaborative project WORTECS objectives and reports on the development of several radio and optical wireless prototypes and a demonstrator targeting mixed reality (MR) application. The aim is to achieve a net throughput of up to Tbps in an indoor heterogeneous network for the MR use case, which seems to be a high throughput "killer application" beyond 5G. A special routing device is associated with the demonstrator to select the most suitable wireless access technology. Post introduction to the project, an overview of the demonstrator is presented with details of the current progress of the prototypes

Optimal WDM Power Allocation via Deep Learning for Radio on Free Space Optics Systems

Radio on Free Space Optics (RoFSO), as a universal platform for heterogeneous wireless services, is able to transmit multiple radio frequency signals at high rates in free space optical networks. This paper investigates the optimal design of power allocation for Wavelength Division Multiplexing (WDM) transmission in RoFSO systems. The proposed problem is a weighted total capacity maximization problem with two constraints of total power limitation and eye safety concern. The model-based Stochastic Dual Gradient algorithm is presented first, which solves the problem exactly by exploiting the null duality gap. The model-free Primal-Dual Deep Learning algorithm is then developed to learn and optimize the power allocation policy with Deep Neural Network (DNN) parametrization, which can be utilized without any knowledge of system models. Numerical simulations are performed to exhibit significant performance of our algorithms compared to the average equal power allocation

Performance Investigation of 1.6 Tbps Hybrid WDM-PDM-OFDM-based Free Space Optics Transmission Link

A novel ultra-high capacity free space optics (FSO) link has been developed by incorporating hybrid wavelength divison multiplexing (WDM)-polarization division multiplexing (PDM)-orthogonal frequency division multiplexing (OFDM) techniques with 16-level quadrature amplitude modulation (16-QAM) signals. Coherent detection is employed to enhance the receiver sensitivity in the presence of channel efects. The proposed link is analyzed under the impact of dynamic weather conditions viz. haze, rain, dust and fog using bit error rate, optical signal to noise ratio, error vector magnitude and maximum transmission range performance metrics. Sixteen independent DWDM channels with 0.8 nm channel spacing each carrying 100 Gbps data are successfully tranported using the proposed FSO link realizing a net data rate of 1.6 Tbps. Furthermore, we demonstrated a performance comparison of the link with contemporary works. The proposed FSO link provides a feasible and viable solution to implement ultra-high-capacity wireless transmission networks for last-mile access.A novel ultra-high capacity free space optics (FSO) link has been developed by incorporating hybrid wavelength divison multiplexing (WDM)-polarization division multiplexing (PDM)-orthogonal frequency division multiplexing (OFDM) techniques with 16-level quadrature amplitude modulation (16-QAM) signals. Coherent detection is employed to enhance the receiver sensitivity in the presence of channel efects. The proposed link is analyzed under the impact of dynamic weather conditions viz. haze, rain, dust and fog using bit error rate, optical signal to noise ratio, error vector magnitude and maximum transmission range performance metrics. Sixteen independent DWDM channels with 0.8 nm channel spacing each carrying 100 Gbps data are successfully tranported using the proposed FSO link realizing a net data rate of 1.6 Tbps. Furthermore, we demonstrated a performance comparison of the link with contemporary works. The proposed FSO link provides a feasible and viable solution to implement ultra-high-capacity wireless transmission networks for last-mile access

Performance evaluation of turbulence-accentuated interchannel crosstalk for hybrid fibre and free-space optical wavelength-division-multiplexing systems using digital pulse-position modulation

A hybrid fibre and free-space optical communication link using digital pulse-position modulation (DPPM) in a wavelength-division-multiplexing system is proposed. Such a system, which could provide a power efficient, robust and flexible solution to high-speed access networks, is a contender for a passive optical network solution and could readily be deployed in areas with restrictions in optical fibre installation, or alternatively as a disaster recovery network. Interchannel crosstalk and atmospheric turbulence are major impairments in such a system and could combine in some cases to degrade the system. Both impairments are investigated here and the results are presented in the form of bit error probability, required optical transmission power and power penalties. Depending on the position of the interferer relative to the desired user, power penalties of about 0.2–3.0 dB for weak turbulence and above 20 dB for strong turbulence regimes are reported for bit error rate of 10−6. DPPM scheme with a coding level of 2 show about 2 dB improvements over on–off-keying scheme

Harnessing the Potential of Optical Communications for the Metaverse

The Metaverse is a digital world that offers an immersive virtual experience. However, the Metaverse applications are bandwidth-hungry and delay-sensitive that require ultrahigh data rates, ultra-low latency, and hyper-intensive computation. To cater for these requirements, optical communication arises as a key pillar in bringing this paradigm into reality. We highlight in this paper the potential of optical communications in the Metaverse. First, we set forth Metaverse requirements in terms of capacity and latency; then, we introduce ultra-high data rates requirements for various Metaverse experiences. Then, we put forward the potential of optical communications to achieve these data rate requirements in backbone, backhaul, fronthaul, and access segments. Both optical fiber and optical wireless communication (OWC) technologies, as well as their current and future expected data rates, are detailed. In addition, we propose a comprehensive set of configurations, connectivity, and equipment necessary for an immersive Metaverse experience. Finally, we identify a set of key enablers and research directions such as analog neuromorphic optical computing, optical intelligent reflective surfaces (IRS), hollow core fiber (HCF), and terahertz (THz)