Light-Emitting Diodes. (Monographs in Electrical and Electronic Engineering.) By A. A. Bergh and P. J. Dean. Pp. viii+591. (Clarendon: Oxford; Oxford University: London, 1976.) £22.

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Light-emitting diodes

Femtocells, despite their name, pose a potentially large disruption to the carefully planned cellular networks that now connect a majority of the planet's citizens to the Internet and with each other. Femtocells - which by the end of 2010 already outnumbered traditional base stations and at the time of publication are being deployed at a rate of about five million a year - both enhance and interfere with this network in ways that are not yet well understood. Will femtocells be crucial for offloading data and video from the creaking traditional network? Or will femtocells prove more trouble than they are worth, undermining decades of careful base station deployment with unpredictable interference while delivering only limited gains? Or possibly neither: are femtocells just a "flash in the pan"; an exciting but short-lived stage of network evolution that will be rendered obsolete by improved WiFi offloading, new backhaul regulations and/or pricing, or other unforeseen technological developments? This tutorial article overviews the history of femtocells, demystifies their key aspects, and provides a preview of the next few years, which the authors believe will see a rapid acceleration towards small cell technology. In the course of the article, we also position and introduce the articles that headline this special issue.

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Femtocells: Past, Present, and Future

In this chapter we deal with the following nonlinear fractional programming problem: 

$$P:\mathop{{\max }}\limits_{{x \in s}} q(x) = (f(x) + \alpha )/((x) + \beta )$$

where f, g: R n → R, α, β ∈ R, S ⊆ R n . To simplify things, and without restricting the generality of the problem, it is usually assumed that, g(x) + β + 0 for all x ∈ S,S is non-empty and that the objective function has a finite optimal value.

Nonlinear Fractional Programming

Visible Light Communication (VLC) is an emerging field in Optical Wireless Communication (OWC) which utilizes the superior modulation bandwidth of Light Emitting Diodes (LEDs) to transmit data. In modern day communication systems, the most popular frequency band is Radio Frequency (RF) mainly due to little interference and good coverage. However, the rapidly dwindling RF spectrum along with increasing wireless network traffic has substantiated the need for greater bandwidth and spectral relief. By combining illumination and communication, VLC provides ubiquitous communication while addressing the shortfalls and limitations of RF communication. This paper provides a comprehensive survey on VLC with an emphasis on challenges faced in indoor applications over the period 1979–2014. VLC is compared with infrared (IR) and RF systems and the necessity for using this beneficial technology in communication systems is justified. The advantages of LEDs compared to traditional lighting technologies are discussed and comparison is done between different types of LEDs currently available. Modulation schemes and dimming techniques for indoor VLC are discussed in detail. Methods needed to improve VLC system performance such as filtering, equalization, compensation, and beamforming are also presented. The recent progress made by various research groups in this field is discussed along with the possible applications of this technology. Finally, the limitations of VLC as well as the probable future directions are presented.

LED Based Indoor Visible Light Communications: State of the Art

Providing ubiquitous connectivity to diverse device types is the key challenge for 5G and beyond 5G (B5G). Unmanned aerial vehicles (UAVs) are expected to be an important component of the upcoming wireless networks that can potentially facilitate wireless broadcast and support high rate transmissions. Compared to the communications with fixed infrastructure, UAV has salient attributes, such as flexible deployment, strong line-of-sight (LoS) connection links, and additional design degrees of freedom with the controlled mobility. In this paper, a comprehensive survey on UAV communication towards 5G/B5G wireless networks is presented. We first briefly introduce essential background and the space-air-ground integrated networks, as well as discuss related research challenges faced by the emerging integrated network architecture. We then provide an exhaustive review of various 5G techniques based on UAV platforms, which we categorize by different domains including physical layer, network layer, and joint communication, computing and caching. In addition, a great number of open research problems are outlined and identified as possible future research directions.

UAV Communications for 5G and Beyond: Recent Advances and Future Trends

Handover Performance of Mobile IPTV over Mobile WiMAX Networks

Internet of Things (IoT) systems, Vehicular system, and mobile communication systems are just a few examples of communication systems that frequently use radio frequency (RF)- based wireless communication technologies. Wireless communication has advantages over traditional wired communication systems due to its simple installation. However, employing high frequencies for wireless communication can pose serious health concerns to people. Several scientists have investigated this subject using visible light in communication systems as opposed to RF waves. Currently, three potential candidates are suitable: Visible Light Communication (VLC), Light Fidelity (LiFi), and Optical Camera Communication (OCC). Deep Learning, which is used to solve complicated issues, develop intelligent solutions, and take the place of human intellect as the driving force behind developing technologies like big data, smart factories, and the IoT, is also having an impact on the future of industry and individuals. In this paper, we propose Multiple-Input Multiple-Output Camera On-Off Keying scheme that makes use of deep learning for detecting and tracking while also taking mobility support and long-distance communication. The performance of this approach will be presented: communication range and low bit error rate.

Design and Implementation of Deep Learning for MIMO C-OOK Scheme-based Optical Camera Communication

Community energy storage system: Deep learning based optimal energy management solution for residential community

Multicast/broadcast services (MBS) are able to provide video services for many users simultaneously. Fixed amount of bandwidth allocation for all of the MBS videos is not effective in terms of bandwidth utilization, overall forced call termination probability, and handover call dropping probability. Therefore, variable bandwidth allocation for the MBS videos can efficiently improve the system performance. In this paper, we propose a bandwidth allocation scheme that efficiently allocates bandwidth among the MBS sessions and the non-MBS traffic calls (e.g., voice, unicast, internet, and other background traffic). The proposed scheme reduces the bandwidth allocation for the MBS sessions during the congested traffic condition only to accommodate more number of calls in the system. Our scheme allocates variable amount of bandwidths for the BMS sessions and the non-MBS traffic calls. The performance analyses show that the proposed bandwidth adaptation scheme maximizes the bandwidth utilization and significantly reduces the handover call dropping probability and overall forced call termination probability.

Bandwidth adaptation for scalable videos over wireless networks

In this paper, we proposed M-ary SS(Spread Spectrum) code added LED-ID system without multiple tag interferences(MTI). The term LED-ID is entitled by corresponding author, and it is defined as LED based ID and tag system. LED-ID consists of a lot of tags and ID receiver. Recently, LED-ID system faced to MTI problem and enhancement of transmission capacity. As one solution to overcome MTI and transmission capacity problems, we proposed M-ary SS code added LED-ID system. From simulation and performance analysis, we certified that the proposed scheme has no multiple tag interferences with enlarged data transmission capacity.

Yeong Min Jang

Papers

Handover Performance of Mobile IPTV over Mobile WiMAX Networks

Design and Implementation of Deep Learning for MIMO C-OOK Scheme-based Optical Camera Communication

Community energy storage system: Deep learning based optimal energy management solution for residential community

Bandwidth adaptation for scalable videos over wireless networks

M-ary SS code added LED-ID system without multiple tag interferences