Reliable data transmissions and offering better mobility to the end user can be achieved by integrating different communication systems. In this paper, we investigate the performance of a cascaded indoor power line communication (PLC)/visible light communication (VLC) system with the presence of an amplify-and-forward (AF) relay. Using the pre-installed infrastructure of electricity wiring networks gives the advantage to use PLC as a backbone for VLCs. The performance of the proposed hybrid system is discussed in terms of the average capacity. A mathematical method is developed for this network to formulate the capacity by exploiting the statistical properties of both the PLC and VLC channels. The derived analytical expressions are validated by Monte Carlo simulations. The results showed that there is a considerable improvement in the performance of the hybrid system as the relay gain increases whereas it deteriorates with increasing the end-to-end distance. A comparison between the performance of a parallel hybrid/PLC and hybrid systems is also provided. It is found that the hybrid/PLC system outperforms the hybrid one. However, the user mobility offered by the latter system remains the main advantage over the former approach.Index Terms-Amplify-and-forward, optical wireless communications, power-line communications, signal-to-noise ratio, visible-light communications, .

The high attenuation which increases as frequency increases in power line communication systems (PLC) makes achieving and sustaining high data rates over such channels a challenging task. In most communication systems, relays are normally deployed to overcome the effect of signal attenuation and to achieve reliable transmissions between users. Amplifyand-forward (AF) and decode-and-forward (DF) relays are often used. In contrast to the existing work on this topic which advocate utilizing relays either between PLC links or between wireless links, the authors of this paper focus on using AF relaying for in-home PLC and wireless systems where one PLC user wants to share data with one wireless user which has no access to the PLC network. We refer to this system as the Hybrid approach. A mathematical method is developed for this network to formulate the capacity of the system by exploiting the statistical properties of both PLC and wireless channels. Monte Carlo simulations are used throughout this paper to validate the analytical results. The impact of several system parameters is investigated in this paper. For the sake of comparison, we also provide the performance analysis and results for a PLC only network. The results showed that the performance of the hybrid system enhances as we increase the relay gain and deteriorates as the end-to-end distance increases. It is also found that the PLC only scheme may outperform the hybrid one if the relay gain is relatively small; however, the user mobility offered by the hybrid system remains the main advantage over the PLC only system. Index Terms-Power-line communications, amplify-andforward, decode-and-forward, wireless communications, signalto-noise ratio.

In multi-hop wireless communication, a sensor node should consume its energy efficiently for relaying of data packets. However, most IoT-devices are equipped with limited battery power and computing resources for wireless communications, and thus energy optimization becomes one of the major concerns in wireless sensors routing design. The wireless technologies usually use unlicensed frequency bands of 2.4 GHz to transmit the data. Due to the broadcasting medium, the wireless transmission interferes with the reception of surrounding radios. As a result, data transmission failure increases resulting in low-communication quality. Therefore, one of the best solutions to this problem is to select the hop distance node that has a few neighbor nodes to disseminate packets until it reaches the ultimate receiver. The proposed routing selects the node that has few neighboring nodes and thus less interference. In another word, the scheme finds a better load balancing, and thus minimizes the probability of overload on a sensor node. It also introduces a new clustering algorithm around a single base station to shorten the transmission distances. This approach periodically selects the cluster heads (CHs) according to its location based distance from the final destination. The extensive simulation studies reveal that the proposed algorithm finds the best routing node and clustering formation to forward the traffic and thereby minimizes the interference ratio. In addition, the proposed protocol achieves low-energy consumption and longer network lifetime than other popular protocols. INDEX TERMS Internet of Things (IoT), routing protocol, path selection, link quality, green computing, link reliability, interference, wireless sensor network (WSN).

Modern railway services are required to deliver good quality services to the passenger throughout the whole journey. These include improved performances, safety, and reduce delays. There is also the requirement for in‐train customer experience such as infotainment and access to reliable communication systems. The railway industry has employed different types and generations of communication systems in recent times. Signaling systems were used at the early stage of the railway services. Today, communication systems such as the second‐generation communication system, also known as the global system for mobile communications (GSM), the Third‐generation (3G) and the Fourth‐generation (4G) are utilized in the railway industry. In this paper, we present a brief history of railway communication systems, their features and applications. In addition, we discuss the technical challenges and potential solutions of in‐train communication systems and how data can be distributed on‐board and between the train coaches using state of the art and hybrid communication technologies.

This paper presents a comprehensive performance analysis of an integrated indoor power line communication (PLC)/visible light communication (VLC) system with the presence of a decode-and-forward (DF) relay. The existing indoor power line networks are used as the backbone for VLCs. The performance of the proposed system is evaluated in terms of the average capacity and the outage probability. A new unified mathematical method is developed for the PLC/VLC system and analytical expressions for the aforementioned performance metrics are derived. Monte Carlo simulations are provided throughout the paper to verify the correctness of the analysis. The results reveal that the performance of the proposed system deteriorates with increasing the end-to-end distance and improves with increasing the relay transmit power. It is also shown that the outage probability of the system under consideration is negatively affected by the vertical distance to user plane.Index Terms-Decode-and-forward (DF), power line communications (PLC), signal-to-noise ratio (SNR), visible light communications (VLC).

The line-of-sight (LoS) channel is one of the requirements for efficient data transmission in visible-light communications (VLC), but this cannot always be guaranteed in indoor applications for a variety of reasons, such as moving objects and the layout of rooms. The relay-assisted VLC system is one of the techniques that can be used to address this issue and ensures seamless connectivity. This paper investigates the performance of half-duplex (HD) conventional DF relay system and cooperative systems (i.e., selective DF (SDF) and incremental DF (IDF)) over VLC channels in terms of outage probability and energy consumption. Analytical expressions for both outage probability and the minimum energy-per-bit performance of the aforementioned relaying systems are derived. Furthermore, Monte Carlo simulations are provided throughout the paper to validate the derived expressions. The results show that exploiting SDF and IDF relaying schemes can achieve approximately 25% and 15% outage probability enhancement compared to single-hop and DF protocols, respectively. The results also demonstrate that the performance of the single-hop VLC system deteriorates when the end-to-end distances become larger. For example, when the vertical distance is 3.5m, the single-hop approach consumes 20%, 40% and 45% more energy in comparison to the DF, SDF, and IDF approaches, respectively.

The transmit power of communication signals over power lines is limited due to restrictions imposed by regulatory bodies and standards. In this paper, the electromagnetic emissions from two different power line communication (PLC) modems are measured in different indoor environments in the frequency range between 1MHz to 30MHz. The obtained measurements are compared with the current available limits and regulations. Also, a comparison between the emission measurements of the two modems is made. Results have shown that, in some scenarios, the measured emissions do not comply with some of the available standards. Based on this, recommendations are made towards the end of the paper.

The last decade has witnessed the rise of the proliferation of Internet-enabled devices. The Internet of Things (IoT) is becoming ever more pervasive in everyday life, connecting an ever-greater array of diverse physical objects. The key vision of the IoT is to bring a massive number of smart devices together in integrated and interconnected heterogeneous networks, making the Internet even more useful. Therefore, this paper introduces a brief introduction to the history and evolution of the Internet. Then, it presents the IoT, which is followed by a list of application domains and enabling technologies. The wireless sensor network (WSN) is revealed as one of the important elements in IoT applications, and the paper describes the relationship between WSNs and the IoT. This research is concerned with developing energy-efficiency techniques for WSNs that enable the IoT. After having identified sources of energy wastage, this paper reviews the literature that discusses the most relevant methods to minimizing the energy exhaustion of IoT and WSNs. We also identify the gaps in the existing literature in terms of energy preservation measures that could be researched and it can be considered in future works. The survey gives a near-complete and up-to-date view of the IoT in the energy field. It provides a summary and recommendations of a large range of energy-efficiency methods proposed in the literature that will help and support future researchers. Please note that the manuscript is an extended version and based on the summary of the Ph.D. thesis. This paper will give to the researchers an introduction to what they need to know and understand about the networks, WSNs, and IoT applications from scratch. Thus, the fundamental purpose of this paper is to introduce research trends and recent work on the use of IoT technology and the conclusion that has been reached as a result of undertaking the Ph.D. study.