Uniform Transmission Power Research Articles

Development of an Anthropomorphic Prosthetic Hand with Underactuated Mechanism

An anthropomorphic prosthetic hand for wrist or forearm amputees is developed herein. The prosthetic hand was designed with an underactuated mechanism, which makes self-adaptive grasping possible, as well as natural motions such as flexion and extension. The finger and thumb modules were designed with four degrees of freedom by motions of the distal interphalangeal, proximal interphalangeal, and metacarpophalangeal joints. In this research, we pursued several novel trials in prosthetic hand design. By using two four-bar linkages composed of a combination of linkages and gears for coupling joints at each finger, it was possible to make a compact design, and the linkage has advantages such as accurate positioning, uniform power transmission, and high payload. Also, by using constant-velocity joints, torque is transferred to finger modules regardless of adduction/abduction motions. In addition, adduction/abduction and self-adaptive grasping motions are passively realized using torsional springs. The developed prosthetic hand was fabricated with a weight of 475 g and a human hand size of 175 mm. Experiments with diverse objects showed its good functionality.

Bifurcation Limits and Non-Idealities Effects in a Three-Phase Dynamic IPT System

Multi-phase dynamic inductive power transfer (D-IPT) systems are capable of achieving uniform power transmission with low control complexity and high efficiency. To achieve acceptable power capabilities, D-IPT systems have to work in resonance configurations. In contrast to transformers, and due to the low coupling coefficient, the compensation is carried out separately in the primary and secondary sides. Consequently, an effect known as bifurcation or pole splitting is created. This causes extra losses in the semiconductors because zero voltage switching (ZVS) is lost. The main objective of this paper is to derive the bifurcation limits for a three-phase D-IPT system. First, the meander coil configuration is introduced. Because this is a system with multiple variables, five assumptions are made to achieve closed-form equations. Therefore, the 36 inductance system is converted into an ideal three inductance problem. With these assumptions, the equations of the coupling, power, and inductance ratio limits are obtained. Afterward, the repercussion of these assumptions is analyzed using illustrations that depict the input impedance angle for various non-ideal conditions. Finally, a 9-kW prototype is used to validate the calculations, analyzing two different operating points: incomplete ZVS and complete ZVS.

Optimum Distance and Power allocation Strategies for Quantum-limited Inter-Relayed FSO Communication System

In this work, we analyze the performance of a uni-directional quantum-limited inter-relay assisted free space optical link. We assume that there is no direct line of sight path between source and destination. The influence of path loss, atmospheric turbulence and pointing error impairments is considered for the analysis. The turbulence induced fading is modeled by independent but not necessarily identically distributed Gamma-Gamma fading statistics. The proposed system employs decode and forward relaying protocol assisted with channel state information. The approximate analytical expression for the probability of error is derived and illustrated by numerical plots. The asymptotic analysis for minimizing error probability in order to find optimum distance between the nodes for uniform power transmission, and for optimizing power allocated to different links, has been performed. It is shown that either distance between the nodes can be optimized for minimizing error probability when uniform power allocation is done, or optimum power allocation can be done for minimizing probability of error. Further, it helps to increase the distance for transmission between source and destination, and can make transmission possible in situations where direct link between source and destination can’t be established due to high rise buildings and other obstacles, while keeping the total transmitted power within permissible levels.

Asymptotic Analysis of Rayleigh Product Channels: A Free Probability Approach

The Rayleigh product channel model is useful in capturing the performance degradation due to rank deficiency of MIMO channels. In this paper, such a performance degradation is investigated via the distribution of mutual information assuming the block fading channels and the uniform power transmission scheme. Using techniques of free probability theory, the asymptotic variance of mutual information is derived when the dimensions of the channel matrices approach infinity. In this asymptotic regime, the mutual information is rigorously proven to be Gaussian distributed. Using the obtained results, a fundamental tradeoff between multiplexing gain and diversity gain of Rayleigh product channels under the uniform power transmission can be characterized by the closed-form expression at any finite signal-to-noise ratio. Numerical results are provided to compare the outage performance between the Rayleigh product channels and the conventional Rayleigh MIMO channels.

Energy Synchronized Transmission Control for Energy-harvesting Sensor Networks

Energy harvesting and recharging techniques have been regarded as a promising solution to ensure sustained operations of wireless sensor networks for longterm applications. To deal with the diversity of energy harvesting and constrained energy storage capability, sensor nodes in such applications usually work in a duty-cycled mode. Consequently, the sleep latency brought by duty-cycled operation is becoming the main challenge. In this work, we study the energy synchronization control problem for such sustainable sensor networks. Intuitively, energy-rich nodes can increase their transmission power in order to improve network performance, while energy-poor nodes can lower transmission power to conserve its precious energy resource. In particular, we propose an energy synchronized transmission control scheme (ESTC) by which each node adaptively selects suitable power levels and data forwarders according to its available energy and traffic load. Based on the large-scale simulations, we validate that our design can improve system performance under different network settings comparing with common uniform transmission power control strategy. Specially, ESTC can enable the perpetual operations of nodes without sacrificing the network lifetime.

Increasing Wireless Adhoc Network Capacity through Simultaneous Transmissions

A great deal of research has been carried out regarding increasing the capacity of wireless networks. The general findings are that increasing the number of nodes in a wireless network decreases individual throughput, simultaneous transmissions cause interference and therefore hinder capacity, and that topology control can increase network power efficiency and reduce the interference within the network. This paper demonstrates that appropriately spaced simultaneous transmissions are beneficial to the capacity of shared spectrum wireless networks and that adding nodes to a wireless network can, in fact, increase its capacity if the nodes are intelligently placed and node transmission powers are appropriately set. In this paper we firstly discuss the inefficiency of high power transmission for networks which allow simultaneous transmissions. It is then demonstrated that if multiple transmitters are utilised simultaneously with uniform transmission power, the network capacity is a local maximum if the required spacing conditions between the receivers are met. In the presence of background noise one can determine that this configuration represents the maximum network capacity achievable. The required separation is defined for the general case and shown to decrease as the number of simultaneous transmissions increases. This result is verified through simulations which demonstrate the construction of high capacity networks. Simulations are also presented which show how existing networks can be augmented with additional nodes and a reduction of transmission power, to exhibit higher uniform average network capacities.

Online Estimation Research of Transmission Line Parameters Based on the Data of Both Ends

The accuracy of power transmission line frequency parameters has a pivotal effect in the accuracy, reliability and safety of various power system analyses and applications, so the actual measurements of transmission line are significant. At present, the measurement of parameters of transmission line is actual measurement in the actual location. The traditional methods can be off-line and have a large number of project contents, then there is a negative impact in people’s life and industrial production. This paper puts forward a novel method which can determine the frequency parameters of power transmission line through the synchronous voltage and current measured from the two terminals. Based on the analysis of frequency parameter measurement methods of uniform power transmission line, we establish the mathematical model and a set of calculation formula based on the information of the two ends of the parameter measurement of transmission line. Subsequently we utilize Matlab power system simulation tools to build the simulation model and get simulation results to validate the correctness of the method.

Robust MIMO Precoding for Several Classes of Channel Uncertainty

The full potential of multi-input multi-output (MIMO) communication systems relies on exploiting channel state information at the transmitter (CSIT), which is, however, often subject to some uncertainty. In this paper, following the worst-case robust philosophy, we consider a robust MIMO precoding design with deterministic imperfect CSIT, formulated as a maximin problem, to maximize the worst-case received signal-to-noise ratio or minimize the worst-case error probability. Given different types of imperfect CSIT in practice, a unified framework is lacking in the literature to tackle various channel uncertainty. In this paper, we address this open problem by considering several classes of uncertainty sets that include most deterministic imperfect CSIT as special cases. We show that, for general convex uncertainty sets, the robust precoder, as the solution to the maximin problem, can be efficiently computed by solving a single convex optimization problem. Furthermore, when it comes to unitarily-invariant convex uncertainty sets, we prove the optimality of a channel-diagonalizing structure and simplify the complex-matrix problem to a real-vector power allocation problem, which is then analytically solved in a waterfilling manner. Finally, for uncertainty sets defined by a generic matrix norm, called the Schatten norm, we provide a fully closed-form solution to the robust precoding design, based on which the robustness of beamforming and uniform-power transmission is investigated.

Optical OFDM Scheme Using Uniform Power Transmission to Mitigate Peak-to-Average Power Effect Over 1040 km Single-Mode Fiber

We investigate the nonlinear effects resulting from the high peak-to-average power ratio of optical orthogonal frequency division multiplexing (OFDM) signals in the optical fiber transmission. To mitigate this nonlinear impairment of optical signals in long-haul communication systems, we propose and experimentally demonstrate a new scheme of the uniform power transmission of 10 Gb/s OFDM signals over 1040 km single-mode fibers in the direct-detection optical OFDM system.

Power-Controlled FCFS Splitting Algorithm for Wireless Networks

We consider random access in wireless networks under a physical interference model, wherein a receiver is capable of power-based capture, i.e., a packet can be correctly decoded in the presence of multiple transmissions if the received signal-to-interference-plus-noise ratio (SINR) exceeds a threshold. We propose a splitting algorithm that varies the transmission power of users on the basis of quaternary channel feedback (idle, success, capture, and collision). We show that our algorithm achieves a maximum stable throughput of 0.5518. Simulation results demonstrate that our algorithm achieves higher throughput and lower delay than those of first-come-first-serve and residual-energy-based splitting algorithms with uniform transmission power.

On the Giant Component of Wireless Multihop Networks in the Presence of Shadowing

In this paper, we study transmission power to secure the connectivity of a network. Instead of requiring all nodes to be connected, we require that only a large fraction (e.g., 95%) be connected, which is called the giant component. We show that, with this slightly relaxed requirement on connectivity, significant energy savings can be achieved for a large-scale network. In particular, we assume that a total of n nodes are randomly independently uniformly distributed in a unit square in Rfr2, that each node has uniform transmission power, and that any two nodes are directly connected if and only if the power that was received by one node from the other node, as determined by the log-normal shadowing model, is larger than or equal to a given threshold. First, we derive an upper bound on the minimum transmission power at which the probability of having a giant component of order above qn for any fixed q isin (0, 1) tends to one as n rarr infin . Second, we derive a lower bound on the minimum transmission power at which the probability of having a connected network tends to one as n rarr infin. We then show that the ratio of the aforementioned transmission power that was required for a giant component to the transmission power that was required for a connected network tends to zero as n rarr infin. This result implies significant energy savings if we require that only most nodes (e.g., 95%) be connected rather than requiring all nodes to be connected. This result is also applicable for any other arbitrary channel model that satisfies certain intuitively reasonable conditions.

전자기 유도 방식 무선 전력 전송을 위한 다중 탭을 갖는 평판형 스파이럴 안테나

본 논문에서는 저주파 자기 유도(magnetic induction)를 이용한 무선 전력 전송 시스템을 위한 새로운 다중탭을 갖는 평판형 스파이럴 안테나 구조를 제시한다. 제안된 안테나는 사각 스파이럴 안테나와 같은 기존 상용안테나에 비해 높은 전송 효율을 가지고, 안테나 개구면에서 고르게 전력을 전송할 수 있다. 검증을 위해 132kHz 저주파에서 자기 유도를 이용한 무선 전력 전송을 위한 송수신 안테나 시제품을 제작하였다. 송신 안테나는 안테나 개구면에서 최대한 많은 양을 균일하게 송신할 수 있도록, 3중 탭을 갖도록 하였다. 수신 안테나는 수신부의 크기를 소형화하기 위해, 2중 탭을 갖도록 설계하였으며, 탭을 위해 단면을 사용한 경우와 직렬로 양면을 사용한 두 경우에 대해 설계 제작하였다. 측정 결과, 제안한 송수신 안테나는 기존의 안테나보다 <TEX>$3{\sim}10$</TEX> dB 이상 큰 전력을 송수신할 수 있었다. In this paper, a novel planar spiral antenna of multi-tabs is proposed for wireless power transmission system based on low frequency magnetic inductive coupling. The proposed antenna has higher transmission efficiency than conventional antennas such a rectangular spiral antenna and a spiral antenna. Also, it has a useful property of uniform power transmission in the region of the antenna aperture. For verification, a transmitting antenna and a receiving one for a wireless power transmission system using magnetic inductive coupling of 132 kHz low frequency are designed and tested. The transmitting antenna has three-tabs spiral of unequal-space for higher uniform magnetic coupling in the antenna aperture. For reducing the receiving antenna size, two receiving antennas of unequal space two-tabs on one-side and series double sides as well are designed, respectively. From measurement, transmission efficiency of the proposed antennas is improved up to <TEX>$3{\sim}10$</TEX> dB compared to conventional antennas.

Joint routing and link rate allocation under bandwidth and energy constraints in sensor networks

In sensor networks, both energy and bandwidth are scarce resources. In the past, many energy efficient routing algorithms have been devised in order to maximize network lifetime, in which wireless link bandwidth has been optimistically assumed to be sufficient. This article shows that ignoring the bandwidth constraint can lead to infeasible routing solutions. As energy constraint affects how data should be routed, link bandwidth also affects not only the routing topology but also the allowed data rate on each link. In this paper, we discuss the sufficient condition on link bandwidth that makes a routing solution feasible, then provide mathematical optimization models to tackle both energy and bandwidth constraints.We first present a basic mathematical model to address using uniform transmission power for routing without data aggregation, then extend it to handle nonuniform transmission power, and then routing with data aggregation. We propose two efficient heuristics to compute the routing topology and link data rate. Simulation results show that these heuristics provide more feasible routing solutions than previous work, and provide significant improvement on throughput and lifetime.

On the connectivity of wireless multi-hop networks with arbitrary wireless channel models

Considering a wireless multi-hop network where a total of n nodes are randomly, independently and uniformly distributed in a unit square in R2 and each node has a uniform transmission power, a fundamental problem is to investigate the connectivity of such networks. In this letter, we prove that the probability of having a connected network and the probability of having no isolated node asymptotically converges to the same value as n goes to infinity for an arbitrary wireless channel model satisfying certain intuitively reasonable conditions.

On the minimax robustness of the uniform transmission power strategy in MIMO systems

In this paper, it is shown that the uniform power allocation across transmit antennas is optimal in the sense that this strategy maximizes the minimum average mutual information of a multiple-input multiple-output system across the class of any arbitrary correlated fading channels, with constraints on the the total fixed transmit power (P/sub Q/), total power of the fades at the transmitter side (P/sub T/), and total power of the fades at the receiver side (P/sub R/), if the channel state information is perfectly known at the receiver side only.