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Buoyant airborne turbines (BATs) are powerful, energy-efficient, adaptive, and environment-friendly. They can be utilized as aerial base stations to expand the wireless network coverage, increase capacity and reliability, improve energy efficiency, and provide a higher line of sight (LoS) probability as they work at higher altitudes. The paper bears the question, what if we equipped a BAT with a complete wireless network base station stack and considered it a new beyond fifth generation/sixth generation (B5G/6G) wireless network device? Therefore, this article discusses enabling BATs as new B5G/6G wireless network equipment. We provide the preliminaries that make the BATs suitable for wireless network applications. We propose the expected configuration and architecture for BATs-based B5G/6G wireless networks. We discuss the opportunities, desired applications, and deployment challenges of BATs in B5G/6G wireless networks. Using simulations, we present the evidence and viability of enabling BATs for extending wireless networks. [Display omitted] • What if we use BATs as a new B5G/6G wireless network device? • BATs are efficient wind turbines with adjustable heights and a mobile ground station. • BATs can serve in B5G/6G wireless networks as a base station. • The simulation results show the BAT gNB capability to serve approximately 120 users (UEs). • The reasonably sized BAT rotor can sufficiently power the 5G gNB base station. [ABSTRACT FROM AUTHOR]

This paper presents an energy-efficient technique for resolving intra-cluster contentions in cluster-based wireless sensor networks. The proposed technique, bit map – binary countdown (BM–BCD), provides collision-free medium access by exchanging short signal tones between the head node and member nodes of the cluster. The BM–BCD improves existing tone-based contention resolution schemes in the following two aspects. Firstly, BM–BCD overcomes the hidden terminal problem by actively involving head node into the contention resolution process. Secondly, BM–BCD introduces a novel group-splitting algorithm which improves energy efficiency of member nodes by spreading the contention resolution over all available elimination rounds. The paper also introduces a simple intra-cluster MAC protocol, named STAR–TONE, which incorporates the proposed BM–BCD, and provides an analytical model for dimensioning main protocol parameters. Our analysis, verified by simulations, demonstrates that BM–BCD reduces the power consumption during contention for up to 44.5% compared to the baseline countdown protocol under bursty traffic conditions. [ABSTRACT FROM AUTHOR]

Abstract In wireless communication systems, energy efficiency (EE) and spectral efficiency (SE) tradeoff is a challenging issue as they are inversely proportional to each other. Most previous work has provided the communication between two points that may lead to the inefficient use of network resources. It is crucial to study optimal power allocation (PA) including relay nodes in order to improve power saving and data rate. This paper proposes a PA optimization method for multi-user, based on EE and SE in Long Term Evolution-Advanced (LTE-A). The optimization problem is formulated as multi-objective optimization (MOO), considering both downlink and uplink transmissions. The mathematical expression of optimal power for EE and SE (OPES) is derived for Transparent and Non-Transparent modes with amplify-and-forward (AF) relay. Numerical results confirm the effectiveness of the proposed OPES formula compared to previously used techniques. [ABSTRACT FROM AUTHOR]

The Internet-of-Things (IoT) represents the next groundbreaking change in information and communication technology (ICT) after the Internet. IoT is concerned with making everything connected and accessible through the Internet. However, IoT objects (things) are characterized by constrained computing and storage resources. Therefore, the Cloud of Things (CoT) paradigm that integrates the Cloud with IoT is proposed to meet the IoT requirements. In CoT, the IoT capabilities (e.g., sensing) are provisioned as services. Unfortunately, the two-tier CoT model is not efficient in the use cases sensitive to delays and energy consumption (e.g., in healthcare). Consequently, Fog Computing is proposed to support such IoT services and applications. This paper reviews the most relevant Fog-enabled CoT system models and proposes an energy-aware allocation strategy for placing application modules (tasks) on Fog devices. Finally, the performance of the proposed strategy is evaluated in comparison with the default allocation and Cloud-only policies, using the iFogSim simulator. The proposed solution was observed to be more energy-efficient, saving approximately 2.72% of the energy compared to Cloud-only and approximately 1.6% of the energy compared to the Fog-default. [ABSTRACT FROM AUTHOR]

This paper studies the optimization problem of energy efficiency in multi-cell networks with multiple users such as 5G network. However, the spectrum allocation and inter-cell interference (ICI) in multi-cell networks are the important challenges. The Soft Frequency Reuse (SFR) scheme which manages the spectrum and reduces ICI is used to build SFR-cellular networks. We take the global energy efficiency of the SFR-cellular network as the objective function of the optimal problem to obtain the maximum energy efficiency. Unfortunately, the objective function is a non-concave function, which is significantly difficult to be solved directly. Therefore, we utilize the fractional program, successive convex approximation, Lagrange dual, and Karush–Kuhn–Tucker (KKT) conditions to transform the objective function into a concave function. In such case, we could solve the problem with the convex optimization method. Finally, based on SFR, we propose a global energy efficiency optimization algorithm to search for the optimal energy efficiency of networks. Simulation results show that the proposed algorithm holds the better performance. [ABSTRACT FROM AUTHOR]

The efficiency of interconnect network-on-chip (NoC) design significantly affects the thermal and energy-consumption problems. The wireless interconnect NoC (WiNoC) design provides a promising NoC architecture for multicast in chip multiprocessor (CMP) as compared with fully wired NoC. However, wireless routers (WRs) cost a larger area size as well as larger energy consumption than wired routers do. In this paper, we study a 2-tier wire–wireless hybrid NoC (WHNoC) architecture in an ( NS ) -processing-element (PE) CMP where N PEs use wires to connect with a wireless-enabled hub forming a star topology subnet and S wireless-enabled hubs form a fully connected WiNoC, named sWHNoC. We first investigate the performance of slotted p -persistent carrier sense multiple access (CSMA) protocol on the fully connected WiNoC. To greatly reduce the energy consumption of WiNoC, we propose an energy-proportional multicast scheme (EMS) by using a power-gating (PG) technique to switch off non-member WRs during the period of multicast transmission. A comprehensive comparison of the star-ring WHNoC, the mesh-based WHNoC, and the proposed sWHNoC is studied. Detailed analyses of the energy consumption of sWHNoC are presented. The correctness of analysis is validated by using Orion 2.0 simulator. Based on our investigation, the sWHNoC with the slotted p -persistent CSMA and the EMS will significantly reduce the energy consumption as well as the transmission latency in CMP. [ABSTRACT FROM AUTHOR]

The necessity and significance of improving the energy efficiency of cloud implementations have increased due to the rapid growth and proliferation of cloud computing services around the world. Virtual machines (VMs) comprise the backend of most, if not all, cloud computing services. Several VMs are often consolidated on a physical machine to efficiently utilize its resources. In this paper, we take into account the cooling and network structure of the datacenter host ing the physical machines when consolidating the VMs so that fewer racks and routers are employed, without compromising the service-level agreements; consequently, idle routing and cooling equipment can be turned off in order to reduce the energy consumption. Our experimental results on four benchmarks show that the proposed techniques improve energy consumption of servers, network equipment, and cooling systems by 2.5%, 18.8%, and 28.2% respectively compared to state of the art, resulting in a total of 14.7% energy improvement on average in the entire datacenter. [ABSTRACT FROM AUTHOR]

• PEM fuel cell is continuously backup power for hybrid power systems. • The efficiency of the inverter varies between 49.671% and 93.794%. • The efficiency of the inverter exhibits superior performance at low hydrogen pressures in stand-alone hybrid PEMFC/Wind/PV power systems. • The inverter efficiency feature of the model has been verified by international standards EN 50530-EN 61853-IEC 61683. Distributed Generation systems are made up of different power generation systems, which are wind turbines, solar panels, fuel cells, energy storage units, micro turbines, and combined heat cycle plants. An inverter is one of the most critical components of Distributed Generation systems. This paper focuses on inverter-based modeling and energy efficiency analysis of the off-grid hybrid system in Distributed Generation. The proposed system is created and simulated using MATLAB/Simulink platform. The obtained results show that the efficiency of the inverter varies between 49.671% and 93.794% under different loads. Model results comply with the inverter efficiency curve specified by the European Commission and U.S. Department of Energy procedures. In the model, the inverter energy efficiency of the hybrid system is compared according to temperature, wind speed, solar radiation, and hydrogen pressure. The inverter exhibits superior performance at low hydrogen pressures. Besides, the efficiency of the inverter is analyzed under load changes. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel location-aware communication mode selection based power control mechanism is proposed for mitigating interference in M2M communications over cellular networks. • Location-aware resource allocation between the MUEs and CUEs that share the resource in both orthogonal and non-orthogonal ways are analyzed for different modes. • A water filling algorithm and Lagrange decomposition scheme based power optimization process are adopted for allocating the proper optimal transmit power to each UE in the proposed mechanism. • Extensive simulation results are carried out for evaluating the performance of the proposed mechanism. The orthogonal resource sharing scheme based proposed mechanism can substantially improve the system performance in terms of per-user energy efficiency (EE) compared to the non-orthogonal resource sharing scheme based proposed mechanism. Machine-to-Machine (M2M) communication is considered as a promising technology in fifth-generation (5G) cellular networks to reduce the power consumption and improve energy efficiency. To achieve these benefits, identification of unknown machine location is crucial for mitigating interference. Therefore, this paper proposes a location-aware communication mode selection based power control mechanism for reducing interference in M2M communications over cellular networks. The proposed mechanism depends on the threshold distance while communicating among M2M pair. Consequently, user equipment (UE) selects the proper communication mode in the proposed mechanism. Resource allocation between the M2M UEs (MUEs) and cellular UEs (CUEs) that share the resources in both orthogonal and non-orthogonal ways are analyzed for different modes. A water filling algorithm and Lagrange decomposition scheme based power optimization process are adopted for allocating the proper optimal transmit power to each UE in the proposed mechanism. Simulation results are compared with the non-orthogonal and orthogonal resource sharing scheme based proposed mechanism which shows that the orthogonal resource sharing scheme provides better system performance in the proposed network. [ABSTRACT FROM AUTHOR]