Single-Photon Based Three-Party Quantum Secure Direct Communication with Identity Authentication

Multipartite quantum secure direct communication (MQSDC) enables multiple message senders to simultaneously and independently transmit secret messages to a message receiver through quantum channels without sharing keys. Existing MQSDC protocols all assume that all the communication parties are legal, which is difficult to guarantee in practical applications. In this study, a single-photon based three-party QSDC protocol with identity authentication is proposed. In the protocol, the message receiver first authenticates the identity of two practical message senders. Only when the identity authentication is passed, the legal message senders can encode their messages by the hyper-encoding technology. In theory, two bits of messages can be transmitted to the message receiver in a communication round. The protocol can resist the external attack and internal attack, and guarantee the security of the transmitted messages and the identity codes of each legal message sender. The secret message capacity of the protocol is simulated with two-decoy-state method. The maximal communication distance between any two communication parties can reach $\approx$31.75 km with weak signal and decoy state pulses. The three-party QSDC protocol can be extended to a general MQSDC protocol and has important application in the further practical MQSDC field.     

Design of a Two-layer Scalable Wavelength Routing Optical Interconnection Network

In this paper, a two-layer scalable wavelength routing optical interconnection network is presented. The top layer of the network is a multi-wavelength bi-directional optical bus which has high-bandwidth and low-latency; the sub-layer of the network is single-wavelength synchronous pipelined ring which has low communication latency and high-scalability. The way to implement the optical system of the network is put forward, and the synchronous pipelined optical interconnect ring is designed and implemented.     

大气紫外传输特性的计算机模拟分析

军事上的紫外告警技术和紫外保密通信技术的需要已成为紫外传感技术发展的重要动力。本文通过采用国际上公认的大气传输特性模拟软件包 L OWTRAN,对由于地理位置、海拔高度、能见度、路径方向以及传输距离等几种因素变化的大气紫外传输特性进行了模拟分析。模拟结果不仅能够基本说明目前在国外紫外传感器技术应用中的一些结论 ,而且对于今后深入开展紫外传感技术的研究具有指导作用     

Communication and time complexity of a distributed election protocol

we evaluate several variants of a standard election algorithm on a ring of processors. The performance measures of interest are the number of messages exchanged (communication complexity) and the execution time (time complexity). Classical models use a synchronism assumption according to which all processors start at the same time and message delays are constant.We attempt to capture the essential asynchronism of this class of algorithms by using probabilistic models. Two such models are discussed, one in discrete and one in continuous time. In each case, both the uni- and the bidirectional cases are studied and compared. We obtain expressions for the distributions of the number of exchanged messages and derive their asymptotic behavior whenn, the number of processors in the ring, grows large. The results show how the communication complexity actually depends on the speed of communcations on the ring, and what is the interest of having bidirectional communications.We also address in part the evaluation of the completion time of the algorithm. This time decomposes into astartup time and anexploration time. We show that the average of the startup time is of the order of logn.     

电磁波在非均匀碰撞等离子体中的透射增强效应

为研究碰撞等离子体对电磁波传输性质的影响,基于电磁波在介质中的传输特性,将等离子体作为一种特殊的介质,针对一定实验条件下的高功率微波（HPM）大气等离子体与一定范围电磁波的透射特性开展了实验、理论及仿真研究。研究发现：S波段HPM在50 Pa真空下形成的等离子体对不同频率的电磁波透射特性具有较大影响,且在一定频率范围内有规律地出现电磁波透射信号增强效应现象;获取了一系列不同频率连续电磁波穿过HPM等离子体区域的透射波形,并对波形进行了归一化处理,在32.4 GHz下,连续电磁波穿过有无等离子体区域的透射系数约有2倍的差异。建立了仿真模型,获得31.5～32.5 GHz范围内透射系数分布曲线图,穿过等离子体的电磁波出现透射增强效应,且在某些频点上出现了约1.9倍的透射增强。该研究成果为HPM大气等离子体在隐身、应急通讯、黑障通讯等方面的应用提供了重要的技术支撑。     

基于ROADM级联的概率成型光传输方法北大核心CSCD

针对概率成型双偏振64-正交幅度调制相干光传输系统,实验研究了可重构光分插复用器(reconfigurable optical add-drop multiplexer,ROADM)级联引起的带宽变窄对系统比特级可实现信息速率(bit-wise achievable information rate,BW AIR)的影响。发射端采用基于麦克斯韦玻尔兹曼分布的3个概率成型分布信号。实验装置包括概率成型符号序列的产生、模拟ROADM级联引起整体频率响应带宽变窄的可变带宽光滤波器、简化检测和BW AIR计算。结果表明:对于不同的星座熵,带宽变窄的影响是相似的;对于给定光信噪比,产生最大BW AIR的星座熵取决于ROADM级联导致带宽变窄的程度。通过选择合适的概率成型星座分布,系统可获得最大化BW AIR。     

Spectral efficiency maximization for IRS-assisted wireless communication in cognitive radio networks

In this paper, we consider the Intelligent reflecting surface (IRS)-assisted cognitive radio (CR) network, in which the IRS is applied to improve the spectral efficiency of secondary users. In specific, the advantages of applying IRS is double: it can not only improve the transmission rate of the secondary users, but also reduce the interference from the secondary users to the primary users, which allow the secondary users to increase the transmission power correspondingly. The original problem is formulated by simultaneously consider the maximum power limitation of the secondary users and the Quality of Service (QoS) requirement of the primary users, which expressed by the interference temperature (IT). The formulated problem is non-convex and difficult to solve directly. We apply the alternating optimization (AO) algorithm to split the original problem into two sub-problems. For the first sub-problem, we transform it into a convex problem and for the second sub-problem, we use the successive convex approximation method to obtain the corresponding results. The simulation experiments show that the performance of our proposed scheme is better than existing schemes.     

UAV path design with connectivity constraint based on deep reinforcement learning

Cellular networks are expected to communicate effectively with unmanned aerial vehicles (UAVs) and support various applications. However, existing cellular networks are primarily designed to cover users on the ground; thus, coverage holes in the sky will exist. In this paper, we investigate the problem of path design for cellular-connected UAVs, taking into account the interruption performance throughout the UAV mission to minimize the completion time. Two types of connectivity constraints requirements are assumed to be available. The first is defined as the maximum continuous time interval that the UAV loses connection with base stations (BSs) below a predefined threshold. For the second, we consider the sum outage of UAV is limited during the entire UAV mission. The UAV is tasked with flying from a starting location to a final destination while minimization the mission time, satisfying the two constraints, separately. The formulated path design problem which involves continues variables and a dynamic radio environment, is not convex and thus is extremely difficult to solve directly. To tackle this challenge, a deep reinforcement learning (DRL) based trajectory design algorithm is proposed, where the Dueling Double Deep Q Network(Dueling DDQN) with multi-steps learning method is applied. Simulation results demonstrate the effectiveness of the proposed DRL algorithm and achieve a trade-off between the trajectory length of the UAV and connection quality.     

Distributed adaptive formation tracking using quantized feedback communication for networked mobile robots with unknown wheel slippage

In this study, we consider a quantized-feedback-communication-based control design problem for the distributed adaptive formation tracking of multiple nonholonomic mobile robots with unknown slippage constraints under capacity-limited network control environments. Uniform-hysteretic quantizers are employed to quantize all the inputs and states of robots and the quantized position information of each robot is only transmitted to neighboring robots through directed networks. Compared with existing literature related to the robot formation, the primary contribution of this paper lies in establishing a novel local adaptive control design methodology to deal with the discontinuity problem caused by using the quantized states of each follower and the quantized position communication of neighboring robots. In the proposed strategy, the communication of the orientations and velocities of neighboring robots is not required for the local control design of follower robots. Moreover, quantized-states-based adaptive compensation schemes are constructed for the effects of signal quantization and wheel slippage. Based on the analysis of quantization errors, the practical stability strategy of the overall closed-loop formation system is derived with the convergence of local tracking errors. Simulation results clarify the proposed formation strategy.     

基于UVC LED的小型化紫外无线通信技术

紫外光通信技术具有低窃听、低位辨、全方位、全天候、抗干扰等优点,而基于紫外光灯的通信系统存在光源体积大、易碎、调制困难、通信速率低、功耗大等问题。设计了一种基于紫外C波段(UVC)LED的小型化无线通信系统方案,并对系统性能进行了理论分析。系统光源采用UVC LED,探测器采用日盲光电倍增管(PMT)和窄带紫外滤光片,通信系统采用开关键控(OOK)和脉冲位置调制(PPM)调制方案。仿真结果表明所设计的紫外无线通信系统可在200mW发射光功率情况下实现直径200m范围内的非视距语音通信和100mW发射光功率情况下实现250m的64Kbps准视距通信。