Cellular Underwater Wireless Optical CDMA Network: Potentials and Challenges

Underwater wireless optical communications is an emerging solution to the expanding demand for broadband links in oceans and seas. In this paper, a cellular underwater wireless optical code division multiple-access (UW-OCDMA) network is proposed to provide broadband links for commercial and military applications. The optical orthogonal codes (OOC) are employed as signature codes of underwater mobile users. Fundamental key aspects of the network such as its backhaul architecture, its potential applications and its design challenges are presented. In particular, the proposed network is used as infrastructure of centralized, decentralized and relay-assisted underwater sensor networks for high-speed real-time monitoring. Furthermore, a promising underwater localization and positioning scheme based on this cellular network is presented. Finally, probable design challenges such as cell edge coverage, blockage avoidance, power control and increasing the network capacity are addressed.Comment: 11 pages, 10 figure

Visible Light Communications towards 5G

5G networks have to offer extremely high capacity for novel streaming applications. One of the most promising approaches is to embed large numbers of co-operating small cells into the macro-cell coverage area. Alternatively, optical wireless based technologies can be adopted as an alternative physical layer offering higher data rates. Visible light communications (VLC) is an emerging technology for future high capacity communication links (it has been accepted to 5GPP) in the visible range of the electromagnetic spectrum (~370–780 nm) utilizing light-emitting diodes (LEDs) simultaneously provide data transmission and room illumination. A major challenge in VLC is the LED modulation bandwidths, which are limited to a few MHz. However, myriad gigabit speed transmission links have already been demonstrated. Non line-of-sight (NLOS) optical wireless is resistant to blocking by people and obstacles and is capable of adapting its’ throughput according to the current channel state information. Concurrently, organic polymer LEDs (PLEDs) have become the focus of enormous attention for solid-state lighting applications due to their advantages over conventional white LEDs such as ultra-low costs, low heating temperature, mechanical flexibility and large photoactive areas when produced with wet processing methods. This paper discusses development of such VLC links with a view to implementing ubiquitous broadcasting networks featuring advanced modulation formats such as orthogonal frequency division multiplexing (OFDM) or carrier-less amplitude and phase modulation (CAP) in conjunction with equalization techniques. Finally, this paper will also summarize the results of the European project ICT COST IC1101 OPTICWISE (Optical Wireless Communications - An Emerging Technology) dealing VLC and OLEDs towards 5G networks

Space-division multiplexing for fiber-wireless communications

We envision the application of optical Space-division Multiplexing (SDM) to the next generation fiber-wireless communications as a firm candidate to increase the end user capacity and provide adaptive radiofrequency-photonic interfaces. This approach relies on the concept of fiber-distributed signal processing, where the SDM fiber provides not only radio access distribution but also broadband microwave photonics signal processing. In particular, we present two different SDM fiber technologies: dispersion-engineered heterogeneous multicore fiber links and multicavity devices built upon the selective inscription of gratings in homogeneous multicore fibers.Comment: 4 pages, 20th International Conference on Transparent Optical Networks (ICTON), Girona (Spain), 2017. arXiv admin note: text overlap with arXiv:1810.1213

Optical wireless communication systems

The emerging field of optical wireless communication (OWC) systems is seen as potential complementary technology to the radio frequency wireless communications in certain applications. It is deemed as a possible technology in the future 5th Generation communication networks to address the spectrum congestion and improve the system's capacity. More research and developments in OWC is still needed in order for it to be adopted in current and future communication systems. This special issue brings together research papers on OWC covering free space optic, visible communications and ultraviolet communications

Radio over Fiber Systems in Cellular Communications: A Systematic Literature Review and Research Agenda

A technology combining wireless communications and fiber optics to transmit radio frequency signals via fiber optic networks is called the Radio Over Fiber system. Capacity, range, reliability, and flexibility of the communication system are advantages offered by this method. Converting RF signals to optical signals using an optical modulation technique is a basic principle of the RoF system, in which they are then transmitted over fiber optic cables. Then, with the use of an optic detector and demodulation technique, that signal is restored to an RF signal at the receiving end. In RoF systems, the reduction of power loss and signal amplification is achieved through optical fiber, which allows transmission over long distances without loss of signal quality. Applications of the RoF system are cellular networks, satellite communications, and remote sensors. In cellular networks, the application of RoF such as expanding cellular network coverage, wireless backhaul, and increasing network capacity. In range expansion, RoF enables the transmission of RF signals from a base station to a remote receiving station via optical fiber, overcoming distance barriers and signal attenuation that occurs in traditional RF transmission. In wireless backhaul, RoF is used to connect base stations with the core network via optical fiber, providing higher capacity and reliability compared to traditional wireless backhaul. To increase network capacity, RoF can move its signal processing and amplifier toward the final users to enhance the data speeds and capacities of cellular networks. It is intended that readers will be able to learn more about Radio Over Fiber systems and their potential for improving the performance of a wireless radio network, as well as how this technology can increase its signal quality when it comes to mobile communications. With the continuous development of RoF technology, it is expected that there will be significant improvements to cellular communication services in the future