• Energy Research

This comprehensive review paper examines the technological advancements towards smart energy management in smart cities. It provides an overview of the concept of smart energy management, the challenges faced by cities in managing their energy consumption, and the need for technological advancements to overcome these challenges. The advancements are categorized based on their applications, such as smart grids, smart buildings, and smart transportation, and their benefits are discussed, including increased efficiency, reduced costs, and better sustainability. The paper also presents case studies of successful implementation of smart energy management technologies and discusses the challenges faced during implementation and how they were overcome. In addition, the paper highlights potential research areas and emerging technologies, including block chain, edge computing, IoT, big data analytics, energy harvesting technologies, machine learning, and distributed energy resources (DERs). The importance of technological advancements for smart energy management in smart cities is emphasized, and recommendations for future research and development in the field are provided. Overall, this review paper contributes to the ongoing development of smart cities and provides valuable insights for researchers, industry professionals, and policymakers working towards a more sustainable future.

Recently, cellular networks’ energy efficiency has garnered research interest from academia and industry because of its considerable economic and ecological effects in the near future. This study proposes an approach to cooperation between the Long-Term Evolution (LTE) and next-generation wireless networks. The fifth-generation (5G) wireless network aims to negotiate a trade-off between wireless network performance (sustaining the demand for high speed packet rates during busy traffic periods) and energy efficiency (EE) by alternating 5G base stations’ (BSs) switching off/on based on the traffic instantaneous load condition and, at the same time, guaranteeing network coverage for mobile subscribers by the remaining active LTE BSs. The particle swarm optimization (PSO) algorithm was used to determine the optimum criteria of the active LTE BSs (transmission power, total antenna gain, spectrum/channel bandwidth, and signal-to-interference-noise ratio) that achieves maximum coverage for the entire area during the switch-off session of 5G BSs. Simulation results indicate that the energy savings can reach 3.52 kW per day, with a maximum data rate of up to 22.4 Gbps at peak traffic hours and 80.64 Mbps during a 5G BS switched-off session along with guaranteed full coverage over the entire region by the remaining active LTE BSs.

The energy consumption of cellular networks has become increasingly important to cellular network operators, due to the significant economic and ecological influence of these networks in the future. The development of alternative energy technologies has resulted in the consideration of a solar powered base station (BS) as a long-term solution for the mobile cellular network industry, to reduce the operational expenditures and CO2 footprints of cellular networks. This study addresses the deployment and operational issues of a solar powered universal mobile telecommunications system (UMTS; a third generation mobile cellular system) BS (i.e., Node B) that is currently deployed (i.e., UMTS Node B 2/2/2 and UMTS Node B 4/4/4). In addition, this study employs a hybrid optimization model for an electric renewable software simulator developed by the American National Renewable Energy Laboratory. Four key aspects are discussed in this study: optimal solar system architecture, energy production, the cash flow of the solar powered UMTS Node B project, and the economic feasibility of a solar powered system compared with traditional sources. Simulation results show that the proposed solution ensures 100% energy autonomy and long-term energy balance for the UMTS Node B, with cost effectiveness.

Massive multiple-input multiple-output (MIMO) is a backbone technology in the fifth-generation (5G) and beyond 5G (B5G) networks. It enhances performance gain, energy efficiency, and spectral efficiency. Unfortunately, a massive number of antennas need sophisticated processing to detect the transmitted signal. Although a detector based on the maximum likelihood (ML) is optimal, it incurs a high computational complexity, and hence, it is not hardware-friendly. In addition, the conventional linear detectors, such as the minimum mean square error (MMSE), include a matrix inversion, which causes a high computational complexity. As an alternative solution, approximate message passing (AMP) algorithm is proposed for data detection in massive MIMO uplink (UL) detectors. Although the AMP algorithm is converging extremely fast, the convergence is not guaranteed. A good initialization influences the convergence rate and affects the performance substantially together and the complexity. In this paper, we exploit several free-matrix-inversion methods, namely, the successive over-relaxation (SOR), the Gauss–Seidel (GS), and the Jacobi (JA), to initialize the AMP-based massive MIMO UL detector. In other words, hybrid detectors are proposed based on AMP, JA, SOR, and GS with an efficient initialization. Numerical results show that proposed detectors achieve a significant performance enhancement and a large reduction in the computational complexity.

Permanent magnet synchronous generator (PMSG)-based wind turbine systems have a wide range of applications, notably, for higher-rated wind energy conversion systems (WECS). A WECS involves integrating several components to generate electrical power effectively on a large scale due to the advanced wind turbine model. However, it offers several glitches during operation due to various factors, notably, mechanical and electrical stresses. This work focuses on evaluating the mechanical and electrical characteristics of the WECS using two individual schemes. Firstly, wind turbines were examined to assess the vibrational signatures of the drive train components for different wind speed profiles. To apply this need, acoustic sensors were employed that record the vibration signals. However, due to substantial environmental impacts, several noises are logged with the observed signal from sensors. Therefore, this work adapted the acoustic signal and empirical wavelet transform (EWT) to assess the vibration frequency and magnitude to avoid mechanical failures. Further, a matrix converter (MC) with input filters was employed to enhance the efficiency of the system with reduced harmonic contents injected into the grid. The simulated results reveal that the efficiency of the matrix converter with input filter attained a significant scale of about 95.75% and outperformed the other existing converting techniques. Moreover, the total harmonic distortion (THD) for voltage and current were examined and found to be at least about 8.24% and 3.16%, respectively. Furthermore, the frequency and magnitude of the vibration signals show a minimum scale for low wind speed profile and higher range for medium wind profile rather than higher wind profile. Consolidating these results from both mechanical and electrical characteristics, it can be perceived that the combination of these schemes improves the efficiency and quality of generated power with pre-estimation of mechanical failures using acoustic signal and EWT.

Network latency will be a critical performance metric for the Fifth Generation (5G) networks expected to be fully rolled out in 2020 through the IMT-2020 project. The multi-user multiple-input multiple-output (MU-MIMO) technology is a key enabler for the 5G massive connectivity criterion, especially from the massive densification perspective. Naturally, it appears that 5G MU-MIMO will face a daunting task to achieve an end-to-end 1 ms ultra-low latency budget if traditional network set-ups criteria are strictly adhered to. Moreover, 5G latency will have added dimensions of scalability and flexibility compared to prior existing deployed technologies. The scalability dimension caters for meeting rapid demand as new applications evolve. While flexibility complements the scalability dimension by investigating novel non-stacked protocol architecture. The goal of this review paper is to deploy ultra-low latency reduction framework for 5G communications considering flexibility and scalability. The Four (4) C framework consisting of cost, complexity, cross-layer and computing is hereby analyzed and discussed. The Four (4) C framework discusses several emerging new technologies of software defined network (SDN), network function virtualization (NFV) and fog networking. This review paper will contribute significantly towards the future implementation of flexible and high capacity ultra-low latency 5G communications.

Avec l'augmentation des gadgets sans fil multimédias abordables, la disponibilité omniprésente de l'accès Internet et le rythme rapide du trafic mobile motivent la recherche vers les communications de cinquième génération (5G) pour réaliser des réseaux d'accès radio en nuage (C-RAN) économes en énergie avec une qualité d'expérience garantie. Exploiter la récolte d'énergie verte pour alimenter le C-RAN réduit considérablement l'approvisionnement en énergie du réseau électrique, l'empreinte carbone et les dépenses opérationnelles. Dans cet article, nous proposons un nouveau paradigme d'équilibrage de charge basé sur la sélection dynamique de points multipoints coordonnés (DPS CoMP), mettant l'accent sur le débit réalisable et l'efficacité énergétique (EE) en réduisant la consommation du réseau de distribution d'électricité du point de vue du réseau. Cet article étudie l'efficacité radio, l'efficacité énergétique et les économies d'énergie moyennes sur le réseau pour relever les principaux défis de la dynamique tempo-spatiale de l'intensité du trafic et de la production d'énergie renouvelable (ER) dans un large éventail de configurations de réseau. La technique d'équilibrage de charge s'efforce d'équilibrer les services publics du réseau tels que l'utilisation de l'énergie verte et l'association d'utilisateurs basée sur la technique de coordination BS dans un cluster. La fourniture d'une approche de veille cellulaire est envisagée pour économiser davantage d'énergie en éteignant les stations de base légèrement chargées (BS) lors des arrivées à faible trafic. L'algorithme d'équilibrage de charge basé sur CoMP proposé gère efficacement l'allocation de blocs de ressources aux nouveaux utilisateurs et augmente l'efficacité énergétique par rapport aux mécanismes conventionnels centrés sur l'emplacement et le trafic. Des simulations approfondies au niveau du système montrent que le cadre suggéré permet un compromis réglable entre l'efficacité radio et l'EE, et permet d'économiser 22 % de la consommation d'énergie sur le réseau et d'augmenter l'indice EE de 32 %. Par la suite, une comparaison exhaustive de la méthode proposée avec les systèmes existants est promise pour une validation ultérieure mettant en évidence les systèmes sans fil 5G durables. Con el aumento de los dispositivos inalámbricos multimedia asequibles, la disponibilidad ubicua del acceso a Internet y el rápido ritmo del tráfico móvil, la investigación hacia las comunicaciones de quinta generación (5G) para realizar redes de acceso de radio en la nube (C-RAN) energéticamente eficientes con una calidad de experiencia garantizada. La explotación de la recolección de energía verde para alimentar la C-RAN alivia sustancialmente la adquisición de energía de la red eléctrica, la huella de carbono y los gastos operativos. En este documento, proponemos un nuevo paradigma de equilibrio de carga basado en la selección dinámica de puntos coordinados multipunto (DPS CoMP) que enfatiza el rendimiento alcanzable y la eficiencia energética (EE) al reducir el consumo de la red de servicios públicos desde una perspectiva a nivel de red. Este documento investiga la eficiencia de radio, EE y el ahorro de energía promedio en la red que aborda los desafíos clave de la dinámica tempo-espacial de la intensidad del tráfico y la generación de energía renovable (RE) en una amplia gama de configuraciones de red. La técnica de equilibrio de carga favorece un equilibrio en las utilidades de la red, como la utilización de energía verde y la asociación de usuarios basada en la técnica de coordinación BS en un clúster. Se contempla la provisión de un enfoque de sueño celular para un mayor ahorro de energía al apagar las estaciones base (BS) ligeramente cargadas durante las llegadas de poco tráfico. El algoritmo de equilibrio de carga basado en CoMP propuesto gestiona de manera competente la asignación de bloques de recursos a los nuevos usuarios y eleva la eficiencia energética con respecto a los mecanismos convencionales centrados en la ubicación y el tráfico. Las extensas simulaciones a nivel de sistema manifiestan que el marco sugerido permite una compensación ajustable entre la eficiencia de la radio y la EE, y ahorra un 22% de consumo de energía en la red y aumenta el índice de EE en un 32%. Posteriormente, se promete una comparación exhaustiva del método propuesto con los esquemas existentes para una validación adicional que destaque los sistemas inalámbricos 5G sostenibles. With the augmentation of affordable multimedia wireless gadgets, the ubiquitous availability of the internet access, and the rapid pace of mobile traffic motivate research towards fifth generation (5G) communications to realize energy-efficient cloud radio access networks (C-RAN) with guaranteed quality of experience. Exploiting green energy harvesting for powering the C-RAN substantially alleviates the energy procurement from the utility grid, carbon footprint, and operational expenses. In this paper, we propose a new dynamic point selection coordinated multipoint (DPS CoMP) based load balancing paradigm emphasizing achievable throughput and energy efficiency (EE) by reducing utility grid consumption from a network level perspective. This paper investigates the radio efficiency, EE, and average on-grid energy saving addressing the key challenges of tempo-spatial dynamics of traffic intensity and renewable energy (RE) generation under a wide range of network setup. Endeavoring load balancing technique strives a balance in network utilities such as green energy utilization and user association based on BS coordination technique in a cluster. Provision of cell sleep approach is contemplated for further energy saving by turning off lightly loaded base stations (BSs) during low traffic arrivals. The proposed CoMP based load balancing algorithm proficiently manages resource block allocation to the new users and elevated the energy efficiency over the conventional location and traffic centric mechanisms. Extensive system-level simulations manifest that the suggested framework enables an adjustable trade-off between radio efficiency and EE, and saves 22% on-grid power consumption and increases EE index by 32%. Afterward, an exhaustive comparison of the proposed method with the existing schemes is pledged for further validation highlighting sustainable 5G wireless systems. مع زيادة الأدوات اللاسلكية متعددة الوسائط بأسعار معقولة، فإن التوافر الواسع النطاق للوصول إلى الإنترنت، والوتيرة السريعة لحركة المرور المتنقلة تحفز البحث نحو اتصالات الجيل الخامس (5G) لتحقيق شبكات الوصول اللاسلكي السحابية الموفرة للطاقة (C - RAN) مع ضمان جودة التجربة. إن استغلال حصاد الطاقة الخضراء لتشغيل C - RAN يخفف بشكل كبير من شراء الطاقة من شبكة المرافق والبصمة الكربونية والنفقات التشغيلية. في هذه الورقة، نقترح نموذجًا جديدًا لموازنة الحمل متعدد النقاط (DPS CoMP) قائمًا على الاختيار الديناميكي للنقاط (DPS CoMP) مع التأكيد على الإنتاجية القابلة للتحقيق وكفاءة الطاقة (EE) من خلال تقليل استهلاك شبكة المرافق من منظور مستوى الشبكة. تبحث هذه الورقة في كفاءة الراديو، و EE، ومتوسط توفير الطاقة على الشبكة التي تعالج التحديات الرئيسية للديناميكيات المكانية الإيقاعية لكثافة حركة المرور وتوليد الطاقة المتجددة (RE) في إطار مجموعة واسعة من إعداد الشبكة. تسعى تقنية موازنة الحمل إلى تحقيق التوازن في مرافق الشبكة مثل استخدام الطاقة الخضراء وارتباط المستخدم بناءً على تقنية تنسيق BS في المجموعة. يتم التفكير في توفير نهج النوم الخلوي لتوفير المزيد من الطاقة عن طريق إيقاف تشغيل المحطات الأساسية ذات التحميل الخفيف (BSs) أثناء وصول حركة المرور المنخفضة. تدير خوارزمية موازنة الحمل القائمة على CoMP المقترحة ببراعة تخصيص كتلة الموارد للمستخدمين الجدد وترفع كفاءة الطاقة على الموقع التقليدي والآليات التي تركز على حركة المرور. تظهر عمليات المحاكاة المكثفة على مستوى النظام أن الإطار المقترح يتيح مفاضلة قابلة للتعديل بين كفاءة الراديو و EE، ويوفر 22 ٪ من استهلاك الطاقة على الشبكة ويزيد مؤشر EE بنسبة 32 ٪. بعد ذلك، يتم التعهد بإجراء مقارنة شاملة للطريقة المقترحة مع المخططات الحالية لمزيد من التحقق من الصحة لتسليط الضوء على الأنظمة اللاسلكية المستدامة للجيل الخامس.

South Korea is the ninth biggest energy consumer and the seventh biggest carbon dioxide emitter in global energy consumption since 2016. Accordingly, the Korean government currently faces a two-fold significant challenge to improve energy security and reduce greenhouse gas emissions. One of the most promising solutions to achieve the goals of sustainable development, energy security, and environmental protection is intensifying the role of renewable energy in electricity production. To this end, the Korean government plans to increase investments in the green energy field, where solar and wind energy will soon play a decisive role toward meeting energy demands and achieving a climate-friendly environment. In this context, this study discusses the future of solar and wind energy in South Korea in four key aspects: (i) opportunities and potential achievement of the vision of government; (ii) potential daily energy output across different geographical areas; (iii) current status and prospects; and (iv) challenges and potential solutions.

Abstract The present study aims to address the sustainability of power resources and environmental conditions for heterogeneous cellular networks. To this end, this study examined an autonomous solar power system to supply heterogeneous cellular networks with their required energy sources. Optimal criteria, system architecture, energy production, and cost analysis are discussed based on the characteristics of solar radiation exposure in South Korea. However, the analysis can be generalized to other cases with a slight difference in daily peak solar hours per case. Additionally, this study compares the feasibility of using an autonomous solar power system to feed heterogeneous cellular networks versus a conventional energy source—i.e., the public electric grid. This study shows that the deployment of the solar power system can satisfactorily meet the energy needs of the base stations (BSs) in heterogeneous cellular networks cost effectively, efficiently, sustainably, and reliably and can improve planning by providing cleaner energy.