The energy efficiency (EE) of femtocells is always limited by the surrounding radio environments in heterogeneous networks (HetNets), such as walls and obstacles. In this paper, we propose to deploy reconfigurable intelligent surfaces (RISs) improve EE femtocells. However, perfect channel state information more difficult obtain due passive characteristics RISs non-cooperative relationship between different tiers. Besides, low-cost transceivers reflecting units suffer nontrivial hardware...

In this article, we investigate and analyze energy recycling for a reconfigurable intelligent surface (RIS)-aided wireless-powered communication network. As opposed to the existing works where harvested by Internet of Things (IoT) devices only comes from power station, IoT are also allowed recycle other devices. particular, propose group switching- user switching-based protocols with time-division multiple access evaluate impact on system performance. Two different optimization problems are,...

The industrial Internet of Things (IIoT) is one the key applications in 5G heterogeneous networks. To support high energy efficiency (EE) and reliability IIoT equipment, it important to design an efficient resource allocation algorithm dynamic complex environments. However, most studies on networks did not address transceiver hardware impairment (HWI) issues (e.g., phase noises, amplifier nonlinearities, quantization errors) corresponding algorithms may be applicable practice. this end,...

Reconfigurable intelligent surface (RIS) has been regarded as a promising technique due to its high array gain, low cost, and power. However, the traditional passive RIS suffers from "double fading" effect, which become major bottleneck in restricting performance of RIS-aided communications. Fortunately, active can alleviate this problem by adjusting phase shift amplifying received signal simultaneously. Nevertheless, beamforming gain often requires large number reflecting elements, leads...

Mobile edge computing (MEC) has been regarded as a promising technique to support latency-sensitivity and computation-intensive serves. However, the low offloading rate caused by random channel fading characteristic becomes major bottleneck in restricting performance of MEC. Fortunately, reconfigurable intelligent surface (RIS) can alleviate this problem since it boost both spectrum- energy-efficiency. Different from existing works adopting either fully active or passive RIS, we propose...

Secure information transmission and energy efficiency (EE) optimization are very important for simultaneous wireless power transfer (SWIPT)-aided heterogeneous networks. However, most of the existing works consider perfect channel state (CSI) linear harvesting (EH) models, which too ideal in practical systems. In this article, we focus on EE-based robust with imperfect CSI nonlinear EH models a SWIPT-aided two-tier macro-femto network multiple eavesdroppers. particular, formulate beamforming...

In deep brine oil and gas injection–production operations, the combined long-term effects of carbon dioxide on rock mechanical properties are not clear. order to solve this problem, influence salt–CO2 environment sandstone is discussed. The mechanism interaction evolution fracture propagation was studied in detail by NMR, triaxial compression test a CT scan. results show that compressive strength mass decrease first then increase with prolonging soaking time. proportion micropores decreased...

Due to the impact of amplifier nonlinearities and phase noise, practical transceivers in heterogeneous networks (HetNets) suffer different degrees hardware impairments (HWIs), which can non-trivially distort received signals even with signal compensations. Traditional beamforming methods HetNets that neglect residual have been proved cause performance degradation. To end, we investigate a realistic design based on max-min fairness multi-cell multiple-input single-output HetNet HWIs. The...

As a promising technology to improve spectrum efficiency and transmission coverage, Heterogeneous Network (HetNet) has attracted the attention of many scholars in recent years. Additionally, with introduction Non-Orthogonal Multiple Access (NOMA) technology, NOMA-assisted HetNet cannot only system capacity but also allow more users utilize same frequency band resource, which makes hot topic. However, traditional resource allocation schemes assume that base stations can exactly estimate...

This letter investigates and analyzes covert communications to safeguard backscatter systems, i.e., how hide backscattering transmission for privacy security, which is rarely a concern yet. Specifically, we consider communication system in the presence of an eavesdropper (Eve), passive tag supported by power source (Alice) attempts communicate reliably while simultaneously guaranteeing covertness Eve. Furthermore, artificial noise (AN) also injected from Alice mislead Eve security purposely....

Reconfigurable intelligent surface (RIS) has become a focal point of extensive research due to its remarkable "squared gain". However, achieving substantial beamforming gain typically requires significant number elements, which leads non-negligible overhead that forwards the coherent phase shift RIS. Different from previous works, primarily focus on information transmission phase, we consider delivery during phase-shift explore trade-off between performance and overhead. To reduce via...

This paper proposes a new cooperative offloading protocol termed "user reciprocity" for backscatter communication (BackCom)-aided mobile edge computing (MEC) systems, whose quintessence is that each user can switch alternately between the active or BackCom mode in different slots, and one works other time slot. Specifically, always use signal transmitted by more data transmission spectrum-sharing manner. To evaluate proposed protocol, computation efficiency (CE) maximization-based...

With the extensive application of networks, access network is receiving wide attention as it connects user terminals and core network. The QoS issue in process data transmission particularly concerned by both terminal users administrators. WiMax, a new popular technology, has defined perfect mechanism at MAC layer. However, bandwidth allocation scheduling algorithm, mechanisms, not been clearly described or protocol. This paper analyzes compares some typical existing algorithms, meanwhile,...

Wireless-powered communication is a promising technique to provide convenient and perpetual energy for energy-constrained wireless devices. However, the uplink information transmission of devices in wireless-powered networks relies on harvested from downlink-energy-transfer power station (PS). To tackle this issue, we propose new intelligent reflecting surface (IRS)-assisted network architecture, where an IRS deployed between PS multiple users enhance efficiency harvesting. The total (EE)...

Smart grid aims to improve the reliability, efficiency, and security of traditional grid, which allows two-way transmission efficiency-driven response. However, a main concern this new technique is that fine-grained metering data may leak personal privacy information customers. Thus, aggregation mechanism for protection required meter report protocol in smart grid. In paper, we propose an efficient privacy-preserving isolated devices. Our consists encryption scheme with additively...

We examine a private ADMM variant for (strongly) convex objectives which is primal-dual iterative method. Each iteration has user with function used to update the primal variable, masked by Gaussian noise local privacy, without directly adding dual variable. Privacy amplification explores if noises from later iterations can enhance privacy guarantee when releasing final variables after last iteration. Cyffers et al. explored proximal variant, where user's entire accessed and added In...

Traffic offloading has been considered as an effective solution to address the problem of network congestion during peak hours. However, with advent emerging huge number wireless users and applications, a new arises: how enhance traffic performance without utilizing more frequency bands. In this letter, we exploit reconfigurable intelligent surface (RIS) for cellular access point networks provide that support dual connectivity stable high-quality connection. Specifically, aim explore...

Abstract In order to better realize the energy-saving operation of urban rail transit trains, considering use regenerative braking energy has become focus current academic research. Train chart optimization, storage system recovery, and inverter feedback are main technical means for its implementation. At present, recovery systems includes super capacitor type, battery flywheel type devices. This paper focuses on recycling method based utilization energy, studies basic working principle...

As the whole world values energy-saving very highly, a monitoring system, which can monitor precise heat consumption data and schedule on demand in time, is urgently needed. This paper presents master station system of wireless automatic reading meter (named as WiHeat-AMRS). It mainly used for residential district heat-supply whose main function measuring heat, charging running status system. The was designed implemented by author own, consists two parts: component back-end database. focuses...

Beamforming design is crucial to reconfigurable intelligent surface (RIS)-aided communication networks. However, most of the existing works assume ideal hardware and perfect channel state information (CSI), which are unrealistic assumptions in practical systems. In order improve system robustness user fairness, this paper, we firstly study max-min energy efficiency problem for RIS-aided heterogeneous networks under non-ideal imperfect CSI. Specifically, joint optimization transmit...