Relay selection and nonlinear energy harvesting in full-duplex multi-relay cooperative network

Energy harvesting (EH) is a promising technique to extend the lifetime energy-constrained devices in wireless networks. This paper analyses the significance of relay selection and non-linear EH in evaluating the performance of Full-duplex (FD) decode-and-forward (DF) multi-relay cooperative network. The relay selection is considered under three scenarios based on channel state information (CSI) availability. We compare the EH performance of a hybrid power-time-splitting (PTS)-based non-linear energy harvester with time-spitting (TS) and power-splitting (PS) EH at the relay node. We derive the expression of outage probability (OP) of FD DF multi-relay cooperative network over independent and identically distributed Rayleigh fading channels. Numerical results show that the outage performance of the system is significantly enhanced by deploying an ideal relay selection scheme. This paper also gives insights about the combined effect of saturation threshold of non-linear EH and residual self-interference (RSI) on the system performance. Unlike linear EH systems, the non-linear EH causes the outage floor even when the RSI is significantly small. The response of the system is also analysed for the impact of TS and PS ratios. Furthermore, we also investigate the system’s performance in terms of other system parameters like the number of relays and data transfer rate. Monte Carlo simulations are used to verify the analytical expressions.     

Outage performance analysis for relay-assisted UWOC systems over GGD weak turbulence with nonzero boresight pointing errors

In this paper, we mainly investigate the outage performance of serial and parallel relay-assisted underwater wireless optical communication (UWOC) systems based on a newly proposed aggregated underwater fading model. In order to overcome the deficiency of the traditional underwater weak turbulence models, that is, they could not accurately fit the measured data in the laboratory, the generalized gamma distribution (GGD) which has been verified by a series of experiments is chosen for the first time to characterize the weak oceanic turbulence. Then, we establish a new receiving signal model which has integrated the implicit path loss plus multipath propagation effect shown by fading free impulse response (FFIR), GGD weak oceanic turbulence, and nonzero boresight pointing errors. Next, we deduce the closed-form expression of the probability density function (PDF) of the hybrid fading considering GGD weak turbulence and nonzero boresight errors based on the new receiving signal model above through double-exponential Taylor expansion and higher transcendental Whittaker function. Finally, the analytical expressions of the outage probabilities for point-to-point (P2P) link, serial and parallel relay-assisted UWOC systems are further derived respectively under the proposed aggregated channel. Numerical simulations are also provided to validate the accuracy of the theoretical formulae derived above, and to show the effects of the key system parameters on the outage performance of relaying UWOC systems.     

Prioritizing the multi-criterial features based on comparative approaches for enhancing security of IoT devices

The Internet of Things (IoT) technologies continuously expand with time due to the advances in automated, connected device technology, mobility, and wide access to information. IoT is the collection of many linked devices due to their unique features, such as scalability, maintainability, fault tolerance, reliability, accuracy, and much more. With the growing number of hybrid devices in large organizations, security and privacy concerns are becoming more challenging. Security is essential for protecting the hardware, network aspects of devices, and information access from unauthorized entities. Most of the security methods and procedures provided by researchers are based on existing Internet security practices. The top-ranking authentication feature categories included the most compatible and common authentication feature for all types of IoT-based devices as an elementary security requirement for protection from unauthorized access. The future challenge is to address the incompatibility of the authentication feature with IoT devices based on appropriate technologies. AI and machine learning are also implementable in order to detect the vulnerability of IoT devices and inform the concerned operator or administration for protection. This research highlights the authentication feature of IoT devices from literature studies and evaluates the significant feature using COPRAS approach to assist organization in enhancing security of IoT devices.     

激光驱动器能源系统实验平台测控系统的研究

 为了提高激光驱动器能源系统运行的稳定性、可靠性、安全性,研制了一套能源系统实验平台的测控系统。该测控系统采用RS-232串行通讯、多线程程序设计来完成并行处理,具有较强的抗干扰能力,可远距离的进行自动控制、数据采集,并能及时的进行数据处理和分析,显示报表并打印。该项研究的结果为大型激光装置的相关系统设计提供了依据。     

长、短周期光纤光栅退火实验研究

光纤光栅技术是光纤通信领域继光纤放大器之后的一个里程碑 ,由此产生的全光纤光子线路及其集成将对光纤通信的发展产生巨大的推动作用。获得性能稳定的光纤光栅具有重要的意义。介绍了长、短周期光纤光栅的光学特性及退火特性     

具有几个光振荡周期的飞秒激光脉冲

从麦克斯韦方程组出发 ,推导出了具有几个光振荡周期的飞秒激光脉冲在非线性光纤中传输的方程和非线性光纤的折射率。给出了描述具有几个光振荡周期的飞秒激光脉冲在非线性光纤中传输方程的解。研究了在非线性光纤中自相位调制导致具有几个光振荡周期的飞秒激光脉冲频谱展宽 (脉宽压缩 )的详细物理过程。研究了非线性光纤中飞秒光孤子产生的条件     

高频半导体激光器组件及其特性的研究

本文使用ＤＣ－ＰＢＨ型激光二极管芯片，设计制作了实用化封装形式的激光器组件；在理论上和实验上研究了组件的封装模型和小信号频率调制特性，其光响应３ｄＢ带宽大于１．８ＧＨｚ。该器件可满足六次群的光通信系统的带宽要求，也可用于ＧＨｚ级的微波副载波光通信系统。     

皮秒脉冲传输系统中三阶色散补偿的研究

模拟了皮秒高斯光脉冲在理想的二阶和三阶色散都作了补偿的光纤链中的传输。结果表明,与二阶色散补偿能消除脉冲展宽一样,三阶色散补偿不仅能防止脉冲展宽,而且也能有效地消除脉冲边沿部的振荡结构和脉知的时移。文中画出了100Gb/s码率的64位高斯光脉冲序列在色散补偿光纤链中传输2000km后的眼图,由眼图的清晰程度可看出这种补偿系统对改善短脉冲传输的有效性。     

850nm光纤中1.1km量子密钥分发实验

在850nm波长完成了一个全光纤量子密钥分发系统原型.该系统以单光子为信息载体,以光纤为量子信道,在通信双方建立起共享的密钥,从而完成量子密钥的分发,其安全性由量子力学基本原理——不确定性原理和量子不可克隆定理所保证.所采取的信息调制方式为相位调制,通信协议采取BB84协议.通信距离为1.1km,有效数据传送速率为3bit/s,误码率为9%左右     

声载波无线电能传输的自适应负载匹配

该文提出了一种可以实现动态阻抗匹配的交直流转换电路及自适应阻抗调节算法,通过可调电容矩阵和可调电感的共振作用实现阻抗匹配,并利用改进的梯度下降算法实现了元器件参数的动态调整,提高了声载波无线电能传输系统在实际应用中的驱动效果和适应能力.研究对提出的电路结构和算法进行了模型仿真,并分析了不同负载接入时系统阻抗的变化及其动...