Power Splitting Ratio Research Articles

Learning uplinks and downlinks transmissions in RF-charging IoT networks

This paper considers uplink and downlink transmissions in a network with radio frequency-powered Internet of Things sensing devices. Unlike prior works, for uplinks, these devices use framed slotted Aloha for channel access. Another key distinction is that it considers uplinks and downlinks scheduling over multiple time slots using only causal information. As a result, the energy level of devices is coupled across time slots, where downlink transmissions in a time slot affect their energy and data transfers in future time slots. To this end, this paper proposes the first learning approach that allows a hybrid access point to optimize its power allocation for downlinks and frame size used for uplinks. Similarly, devices learn to optimize (1) their transmission probability and data slot in each uplink frame, and (2) power split ratio, which determines their harvested energy and data rate. The results show our learning approach achieved an average sum rate that is higher than non-learning approaches that employed Aloha, time division multiple access, and round-robin to schedule downlinks or/and uplinks.

Multi-UAV trajectory planning for RIS-assisted SWIPT system under connectivity preservation

Effective information transmission and energy supply are essential for low-power Internet-of-things (IoT) devices, particularly in geographically constrained or disaster-affected areas. As an emerging technology, simultaneous wireless information and power transfer (SWIPT) ensures uninterrupted communication through supplying power, thereby eliminating issues related to battery depletion. Owing to the high maneuverability, unmanned aerial vehicle (UAV) has enabled SWIPT a new paradigm by providing flexible and on-demand service. However, maintaining connectivity among UAVs while they execute tasks is a critical challenge, for their powerful online decision-making relies on information sharing. Unfortunately, this issue is often overlooked in existing literature on UAV-aided wireless communication. In this paper, a novel connectivity preserved multi-agent deep reinforcement learning algorithm (CP-MARL) is designed to solve the trajectory planning problem in complex environments, where multi UAVs cooperatively provide SWIPT service for ground users (GUs) while ensuring seamless information exchange. Moreover, fairness of service received among GUs is also considered, as unequal resource allocation can lead to suboptimal system performance. Besides, reconfigurable intelligent surface (RIS) is adopted to redirect signals to achieve line-of-sight (LoS) channel. Under this framework, the fair energy efficiency is maximized by jointly optimizing the UAVs’ trajectory, the phase shift of RIS, power splitting (PS) ratio and the association relationships between UAVs and GUs. The formulated problem is inherently non-convex but the proposed CP-MARL algorithm successfully delivers online near-optimal solutions. Numerical results demonstrate that compared with benchmark solutions, the designed CP-MARL algorithm significantly enhances the energy-efficiency performance of the system, achieving 40.22% performance improvement compared to scenarios where connectivity is not maintained, along with a more stable training process. Additionally, the superiority of incorporating RIS in this system is corroborated by the 27.31% improvement in energy-efficiency.

Secrecy outage probability of IRS‐aided VLC systems with power splitting

AbstractAn intelligent reflecting surface (IRS)‐aided visible light secure communication system is investigated. In order to improve its security performance, a power splitting scheme is adopted at the light‐emitting diodes. In contrast to most current research on the physical‐layer security in IRS‐aided visible light secure communication systems where secrecy rate or secrecy capacity maximization problems subject to various resource constraints were formulated, this letter takes the reliability of secure transmission into account. The closed‐form expression of secrecy outage probability is derived based on the statistical characteristics of the signal‐to‐noise ratio of the legitimate user, and the effects of light‐emitting diodes and IRS parameters and power splitting ratio on the secrecy outage probability are validated through simulations.

Transmit Power Optimization in Multihop Amplify-and-Forward Relay Systems with Simultaneous Wireless Information and Power Transfer

In this paper, we study a multi-hop amplify-and-forward (AF) simultaneous wireless information and power transmission (SWIPT) relay system. Each relay node harvests power using a power split (PS) method from a portion of the received signal, amplifies the remaining received signal, and passes it to the next relay. Based on this system model and signal flow, we derived and solved the convex power minimization problem with the optimal PS ratio. In this case, it was found that using the optimal PS ratio consumed a lower amount of power than when using a fixed PS ratio (0.5). We then investigated the impact of processing cost on the AF-SWIPT system using decoding and forwarding SWIPT as benchmarks, and found that AF-SWIPT was superior.

Robust and broadband tap couplers using misaligned waveguides based on thin-film lithium niobate.

Robust and high-performance power splitters with an ability to partition the input light power into different proportions are vital for various on-chip optical systems. Here we propose and experimentally demonstrate several tap couplers with unbalanced power splitting ratios (PSRs) from 4%: 96% to 40%: 60% using misaligned waveguides on thin-film lithium niobate (TFLN). The device utilizes misaligned waveguide width differences to obtain a flat power splitting ratio over a broadband optical wavelength. The measured results indicate that all the proposed devices exhibit less than 2% PSR variation over a 120 nm optical bandwidth from 1500 nm to 1620 nm and over ±100 nm planar fabrication tolerance. The demonstrated tap couplers offer a promising application prospect in high-density photonic integrated circuits.

Full-duplex cooperative relaying systems for simultaneous wireless information and power transfer with non-orthogonal multiple access

In this research, we propose a system model based on cooperative non-orthogonal multiple access (NOMA) for simultaneous wireless information and power transfer (SWIPT) within a full-duplex (FD) communication framework. We investigate two protocols - time switching protocol (TSR) and power splitting protocol (PSR) - designed to accommodate delay-tolerant-transmission (DTT) as well as delay-limited-transmission (DLT), thereby improving data processing and energy harvesting (EH). We present explicit formulas for pivotal performance measures such as energy efficiency, ergodic rate, throughput, and outage probability. These performance measures are thoroughly evaluated in numerous specifications, encompassing inter-user separation, required spectral efficiency, EH efficiency, time and power splitting ratios in moderate-to-high signal-to-noise ratio scenarios. The results expose improved EH efficiency, hence meliorated transmission reliability. Importantly, NOMA in the proposed system model is proved to be considerably better than traditional orthogonal multiple access.

UAV aided NOMA relaying with energy harvesting architecture: Performance analysis

In this work, we consider a dual hop Non Orthogonal Miltiple Access (NOMA) based communication network between Source S and two destination users UA , UB which is aided by an Unmanned Aerial Vehicle (UAV) relay R. The energy constrained UAV relay harvests energy from signal transmitted by the source through Power Splitting (PS) and further transmits the signal using Amplify and Forward (AF) protocol to the destination users through NOMA. For the proposed network, we derive analytical expressions for outage probability and ergodic capacity. The impact of parameters like PS ratio and UAV altitude is studied on the overall system performance. Further, the performance of the proposed system is also compared with Orthogonal Multiple Access (OMA) scheme. The results obtained show that the energy harvesting capacity of UAV is significantly affected under Linear and Non Linear EH models. The numerical analysis done is verified through Monte Carlo Simulations.

Adaptive Control for Underwater Simultaneous Lightwave Information and Power Transfer: A Hierarchical Deep-Reinforcement Approach

In this work, we consider a point-to-point underwater optical wireless communication scenario where an underwater sensor (US) transmits its sensing data to a remotely operated vehicle (ROV). Before the US transmits its data to the ROV, the ROV performs simultaneous lightwave information and power transfer (SLIPT), delivering both control data and lightwave power to the US. Under the considered scenario, our objective is to maximize energy harvesting at the US while supporting predetermined communication performance between the two nodes. To achieve this objective, we develop a hierarchical deep Q-network (DQN)–deep deterministic policy gradient (DDPG)-based online algorithm. This algorithm involves two reinforcement learning agents: the ROV and US. The role of the ROV agent is to determine an optimal beam-divergence angle that maximizes the received optical signal power at the US while ensuring a seamless optical link. Meanwhile, the US agent, which is influenced by the decision of the ROV agent, is responsible for determining the time-switching and power-splitting ratios to maximize energy harvesting without compromising the required communication performance. Unlike existing studies that do not account for adaptive parameter control in underwater SLIPT, the proposed algorithm’s adaptive nature allows for the dynamic fine-tuning of optimization parameters in response to varying underwater environmental conditions and diverse user requirements.

MEMS‐enabled Ultralow Power Consumption Programmable Arbitrary Order Mode Switch

AbstractMode‐division‐multiplexing (MDM) recently attracted much interest due to its ability to enhance the capacity for optical information communication. To meet growing data transmission demands and enable flexible on‐chip mode manipulation, programmable optical mode converter switches are essential. This work introduces a micro‐electromechanical‐system (MEMS)‐enabled programmable arbitrary order mode switch, capitalizing on the benefits of MEMS technology such as low power consumption, robust modulation capabilities, and seamless large‐scale integration. Employing newly developed MEMS‐tunable mode converter (MTMC) units, the system achieves high conversion efficiencies from the fundamental mode to arbitrary higher‐order modes and supports programmable power distribution among different modes by cascading multiple MTMCs. As a proof‐of‐concept, a programmable TE0–TE0/1/2 mode switch operates in the 3.64 to 3.71 µm wavelength range, achieving maximum crosstalk values of –9.56 and –9.88 dB for TE0 to TE1 and TE0 to TE2 mode conversion, respectively, and a remarkably low power consumption of 67 pW. Furthermore, a programmable mode multiplexer is developed by simultaneously actuating two MEMS actuators to modulate phase matching conditions, enabling arbitrary power splitting ratios among these modes. The demonstrated scalability and flexibility of the proposed system highlight its potential as a foundational component for MDM systems.

Energy Minimization for IRS-Assisted SWIPT-MEC System.

With the rapid development of the internet of things (IoT) era, IoT devices may face limitations in battery capacity and computational capability. Simultaneous wireless information and power transfer (SWIPT) and mobile edge computing (MEC) have emerged as promising technologies to address these challenges. Due to wireless channel fading and susceptibility to obstacles, this paper introduces intelligent reflecting surfaces (IRS) to enhance the spectral and energy efficiency of wireless networks. We propose a system model for IRS-assisted uplink offloading computation, downlink offloading computation results, and simultaneous energy transfer. Considering constraints such as IRS phase shifts, latency, energy harvesting, and offloading transmit power, we jointly optimize the CPU frequency of IoT devices, offloading transmit power, local computation workload, power splitting (PS) ratio, and IRS phase shifts. This establishes a multi-variate coupled nonlinear problem aimed at minimizing IoT devices energy consumption. We design an effective alternating optimization (AO) iterative algorithm based on block coordinate descent, and utilize closed-form solutions, Dinkelbach-based Lagrange dual method, and semidefinite relaxation (SDR) method to minimize IoT devices energy consumption. Simulation results demonstrate that the proposed scheme achieves lower energy consumption compared to other resource allocation strategies.

Arbitrary low-frequency power-splitting strategy in ferrite/piezoelectric magnetoelectric heterostructures: theory and experimental validation

Exploring low-frequency (LF) arbitrary power-splitting technologies to address the independent excitation issues of LF/VLF mechanical antennas (MA) with random distributions is challenging due to unidentified device construction and operation mechanism. In light of this, a device construction strategy for three-port magnetoelectric (ME) arbitrary power splitter in composite of ferrite/piezoelectric heterostructure, as well as theoretical model was developed. To validate the feasibility and effectiveness of the strategy, three size-tailored ME samples with length ratio of split PZT segments in 1:1, 2:1, and 3:2 were modeled, fabricated and comparatively characterized. Experimental results show that the achievable maximum power conversion efficiencies (PE) reach 52%, 71%, and 59% for three tailored ME samples, respectively, and as expected the power-splitting ratios are directly proportional to the square ratio of ME voltage coefficient (MEVC) from each port of the tailored ME samples, which are in coincidence with theory under desired operation stability and favorable experiment repeatability evaluated by uncertainties of 0.25854 V cm−1 Oe−1 and 0.32979 V cm−1 Oe−1 for each port. Therefore, a prediction of evolutionary tendency for arbitrary power splitter realization was expanded in view of our experimental observations, and a great flexibility for device future design and further optimization was also provided. Therefore, the presented LF power-splitting strategy paves the ways for arbitrary power splitter realization and enriches the multi-functional ME power electronics families, as well as enables potential applications for efficient excitations of MAs in high-permeable military underwater and civilian emergency rescue distribution long-wave communication system for practical scenarios of submarine, underground railways, tunnels and collapsed residential buildings.

Simulation of a SiN 2 × 2 adiabatic 3-dB coupler for 800-nm to 1000-nm wavelength range

We conducted numerical simulations on a 2×2 adiabatic 3-dB coupler tailored for the 800-nm to 1000-nm range, operating on a silicon-nitride (SiN) platform. Through the finite difference time domain method, we achieved a power splitting ratio close to 3 dB with a tight tolerance of ±0.27dB and an insertion loss below 0.19 dB across the wavelength range of 800 nm to 1000 nm. Additionally, we simulated a 2×2 switch utilizing two 2×2 adiabatic 3-dB couplers, revealing a theoretical extinction loss of approximately −14dB, particularly prominent around 900 nm.

A centralized fleet management system for electrified transportation

Abstract Hybrid Electric Vehicles are a promising alternative to Conventional and Electric Vehicles, as they offer better fuel economy, lower emissions, and long drive range without requiring extensive charging infrastructure. Limited driving range and battery degradation in electric vehicles are the main challenges in electrified fleets working in large metropolitan. For these challenges, the hybrid electric vehicle fleet management system is an effective solution to optimize power consumption and mitigate electric vehicle and conventional vehicle challenges. This paper proposes a hybrid electric vehicle fleet management system for public transportation, to analyze and investigate the performance and energy consumption rate of conventional, electric, and hybrid electric vehicles on different routes using representative driving cycles. The hybrid electric vehicle fleet management system enhances operational efficiency for the fleet management system and reduces power consumption in transportation. The proposed work comprises a hybrid electric vehicle model that is based on object-oriented programming. The proposed work offers the ability to add the input of the initial state of charge, power split ratio, and route data for each bus, and the hybrid electric vehicle model computes the state of charge and fuel consumption rate along the road. Finally, The proposed work shows how a hybrid electric vehicle fleet management system has a significant potential to be a solution for public transportation in Egyptian urban areas at this time compared with conventional vehicle and electric vehicle fleet management systems.

Design and validation of a miniaturized reconfigurable power divider with arbitrary power split ratio and flexible output phase difference

This study introduces a microstrip line (ML) based reconfigurable 5-port power divider (PD) capable of manipulating power ratios at four output ports. The proposed PD offers two operational modes: unidirectional and bidirectional. In unidirectional transmission mode, the entire source power is directed to a particular output port, while in bidirectional transmission mode, the source power is equally distributed between two output ports. The selection of different transmission modes is accomplished by configuring six adaptive loads that are coupled to the PD structure, and the corresponding S-parameters of the proposed PD are derived by even–odd mode modeling. The resulting data is subsequently optimized by a numerical approach to identify the required design parameters that would ensure optimal performance. The proposed PD resonates at 1.06GHz and covers a frequency range spanning 0.9GHz to 1.2GHz, making it an excellent option for supplying regulated power to multi-port antennas or multiple input multiple output (MIMO) antennas proposed for aircraft navigation applications. The prototype has been developed to validate the notion of reconfigurable reactive loads utilizing varactor diodes and the recorded result is evaluated with the simulated results. The findings confirm excellent performance with regards to insertion loss (with a difference of <-2dB from the optimal values), reflection coefficient (≥-20dB), and isolation (≥-40dB) between the transmitting (input port) and non-transmitting or the remaining ports.

Low-loss and broadband arbitrary ratios 1 × 2 power splitter based on asymmetrically tapered multimode interference

This work presents a low-loss and broadband 1 × 2 power splitter with arbitrary power splitting ratios (PSRs) based on asymmetrically tapered multimode interference. The asymmetrically input tapered waveguide is employed to gradually alter the direction of light propagating in the multimode region. Experimental results show that the device can maintain low losses (∼0.2–0.4 dB) with adjusted PSRs ranging from 50%:50% to 75%:25% at 1550 nm. The adjustable range of PSRs can be extended by increasing the asymmetry of the structure. Additionally, its performance is weakly dependent on wavelength within the range of 1530–1565 nm. Benefiting from the gradual alteration of the direction of light propagation, the device exhibits a low output phase difference of ±8.7°, and the maximum phase deviation is below 6.2° over the wavelength range from 1500 nm to 1600 nm.

Sum-rate maximization for a distributed space-time block code-aided cooperative NOMA with energy harvesting

AbstractIn this paper, we exploit the spatial and transmission diversities in cooperative non-orthogonal multiple access (C-NOMA) networks to improve the system sum-rate. To achieve this, we propose a user-pairing scheme where near-field user pairs serve as relays for user pairs in the far-field region. Based on this pairing scheme, we incorporate a space-time block code transmission technique at the near-field user pairs to maximize the transmission diversity in the cooperative phase. Moreover, we consider a non-linear energy harvesting model at the near-field user pair to alleviate the problem of energy consumption during the cooperative transmission phase. Further to this, we formulate a sum-rate maximization problem that is addressed from the viewpoint of joint power allocation factor and power splitting ratio optimization. We develop a low-computational iterative algorithm based on the concepts of the Stackelberg game and the Nash bargaining solution. We benchmark our findings with different scenarios, such as energy harvesting C-NOMA with a fixed power allocation factor and power splitting ratio, energy harvesting C-NOMA without STBC, non-cooperative NOMA, and orthogonal multiple access. The results obtained via simulations outperform the benchmark schemes.

Compact Low Loss Ribbed Asymmetric Multimode Interference Power Splitter

Optical power splitters (OPSs) are utilized extensively in integrated photonic circuits, drawing significant interest in research on power splitters with adjustable splitting ratios. This paper introduces a compact, low-loss 1 × 2 asymmetric multimode interferometric (MMI) optical power splitter on a silicon-on-insulator (SOI) platform. The device is simulated using the finite difference method (FDM) and eigenmode expansion solver (EME). It is possible to attain various output power splitting ratios by making the geometry of the MMI central section asymmetric relative to the propagation axis. Six distinct optical power splitters are designed with unconventional splitting ratios in this paper, which substantiates that the device can achieve any power splitter ratios (PSRs) in the range of 95:5 to 50:50. The dimensions of the multimode section were established at 2.9 × (9.5–10.9) μm. Simulation results show a range of unique advantages of the device, including a low extra loss of less than 0.4 dB, good fabrication tolerance, and power splitting ratio fluctuation below 3% across the 1500 nm to 1600 nm wavelength span.

Joint beamforming and power splitting design for MISO downlink communication with SWIPT: a comparison between cell-free massive MIMO and small-cell deployments

Simultaneous wireless information and power transfer (SWIPT) has been advocated as a highly promising technology for enhancing the capabilities of 5G and 6G devices. However, the challenge of dealing with large propagation path loss poses a significant hurdle. To address this issue, massive multiple-input multiple-output (MIMO) is employed to enhance the efficiency of SWIPT in cellular-based networks with multiple small cells, and especially increase the energy for cell-edge users. In addition, by leveraging a large set of spatially distributed base stations to collaboratively serve SWIPT-enabled user equipment, the cell-free massive MIMO has the potential to provide even better performance than the conventional small-cell systems. In this work, we extend the investigation to include the application of SWIPT technology with alternating current (AC) logic in the cell-free networks and the small-cell networks and propose joint beamforming and power splitting optimization frameworks to maximize the system sum-rate, subject to the constraints on harvested energy, AC logic energy supply, and total transmit power. The optimization problem is shown to be non-convex, posing a significant challenge. To address this challenge, we resort to a two-stage decomposition approach. Specifically, we first introduce quadratic transform-based fractional programming (FP) algorithms to iteratively solve the non-convex optimization problems in the first stage, achieving near-optimal solutions with low time complexities. To further reduce the complexities, we also incorporate conventional schemes such as zero forcing, maximum ratio transmission, and signal-to-leakage-and-noise ratio for the design of beamforming vectors. Second, to determine the optimal power splitting ratio within the framework, we develop a one-dimensional (1-D) search algorithm to tackle the single variable optimization problem reduced in the second stage. These algorithms are then evaluated in the context of cell-free MIMO and small-cell networks with numerical experiments. The results show that the FP-based algorithms can consistently outperform those utilizing the conventional beamforming schemes, and the solutions of this work can achieve up to fivefold improvement in the system sum-rate than the small-cell counterpart while providing different but comparable performance trends in energy harvesting (EH).

Multi-hop clustering routing protocol design based on simultaneous wireless information and power transfer technology and imperfect spectrum sensing for EH-CRSNs

Existing clustering routing protocols for multi-hop energy harvesting-cognitive radio sensor networks (EH-CRSNs) generally assume perfect spectrum sensing, which is not aligned with the practical spectrum sensing capabilities of nodes in real networks. Additionally, the severe imbalance in residual energy among cluster heads (CHs) negatively affects the successful data delivery. To resolve these problems, this paper introduces a simultaneous wireless information and power transfer (SWIPT)- and imperfect spectrum sensing-based multi-hop clustering routing protocol (ES-ISSMCRP). ES-ISSMCRP makes full use of downlink EH and intra-cluster SWIPT technologies to replenish and equalize the remaining energy among nodes, further extending network lifespan while maintaining network surveillance capabilities. Specifically, to reduce the adverse impact of imperfect spectrum sensing on network performance and improve energy utilization, this paper proposes an EH-based energy level function and associated selection criteria for CHs and relays, facilitating distributed cluster formation and multi-hop routing selection between clusters. To equalize the residual energy among nodes within a cluster, ES-ISSMCRP protocol enables cluster members (CMs) to decide whether employ SWIPT technology with a power splitting (PS) receiver architecture to transmit energy to their CH while sending data. The actual energy value transmitted by CMs using SWIPT technology is deduced by calculating the PS ratio and the expected energy expenditure of nodes for data transmission. Simulation results show that ES-ISSMCRP protocol offers significant improvements over other comparative protocols in terms of extending network lifespan and enhancing network surveillance capabilities.

Ultracompact and ultrabroadband arbitrary ratio power splitter using subwavelength gratings

An ultracompact and ultrabroadband arbitrary ratio power splitter based on adiabatically tapered silicon waveguides, with subwavelength gratings in the coupling region, is proposed and demonstrated experimentally. Various power splitting ratios (PSRs) can be implemented by flexibly manipulating the gap of two adjacent tapered waveguides. The wavelength dependence is greatly reduced by introducing subwavelength gratings. Simulation results show that our proposed device has a 400 nm (1300 nm–1700 nm) bandwidth with an insertion loss &lt;0.5dB for PSRs of 50:50, 60:40, 70:30, 80:20, and 90:10, and the corresponding total device length is only 2.9 µm. The experimental results indicate that the insertion loss is lower than 0.82 dB over a wide bandwidth of 80 nm, and there is a PSR variation less than 2.5% in the range of 1530 nm to 1610 nm.