A 16-QAM 45-Gbps 7-m Wireless Link Using InP HEMT LNA and GaAs SBD Mixers at 220-GHz-Band

This paper presents a 220-GHz-band 7-m wireless link with a 45-Gbps transmission data rate by using 16 quadrature amplitude modulation(16-QAM).Super-heterodyne transceiver modules are developed for transmission and reception of the modulated signals,which consist of a Schottky barrier diodes(SBD)based sub-harmonic mixer(SHM),an InP HEMT low noise amplifier(LNA),a waveguide band-pass filter(BPF),and a 108-GHz local oscillator(LO)multiplier chain.The transmitter features a peak transmit power of 1.41 dBm,and the IF frequency varies from 5 GHz to 20 GHz.Besides,the receiver features a conversion gain of 9.3 dB in average and a noise temperature of 3052.8 K.The measured results indicate that the transceiver modules enable data transmission of a 45-Gbps 16-QAM signal with Signal-Noise-Ratio(SNR)from 11.59 dB to 15.36 dB in a 7-m line-of-sight channel.

In-situ manipulation of wireless link with reinforcement-learningdriven programmable metasurface in indoor environment

It is of great importance to control flexibly wireless links in the modern society,especially with the advent of the Internet of Things(IoT),fifth-generation communication(5G),and beyond.Recently,we have witnessed that programmable metasurface(PM)or reconfigurable intelligent surface(RIS)has become a key enabling technology for manipulating flexibly the wireless link;however,one fundamental but challenging issue is to online design the PM's control sequence in a complicated wireless environment,such as the real-world indoor environment.Here,we propose a reinforcement learning(RL)approach to online control of the PM and thus in-situ improve the quality of the underline wireless link.We designed an inexpensive one-bit PM working at around 2.442 GHz and developed associated RL algorithms,and demonstrated experimentally that it is capable of enhancing the quality of commodity wireless link by a factor of about 10 dB and beyond in multiple scenarios,even if the wireless transmitter is in the glancing angle of the PM in the realworld indoor environment.Moreover,we also prove that our RL algorithm can be extended to improve the wireless signals of receivers in dual-receiver scenario.We faithfully expect that the presented technique could hold important potentials in future wireless communication,smart homes,and many other fields.

A low-cost 10-Gbit/s millimeter-wave wireless link working at E-band

Test results for a 10-Gbps prototype demonstrator working at 71~76 GHz frequency band with a 2-bit/s/Hz spectral efficiency are reported.To overcome the speed limitation of the commercial DA/ADs,a two-channel analog IF multiplexing and demultiplexing topology is adopted as a trade-off between cost and spectrum efficiency.The same approach is also used to achieve up to 20 Gbps with a full 10-GHz bandwidth of the allocated commercial bands(71~76 GHz and 81~86 GHz).

经典Link数据链信道传输模型及特性研究

随着生活节奏不断加快,对通信信息的实时接收要求越来越高,需要各类信息能够快速传递,各个工作节点单元信息的共享、协作、同步已经逐渐成为成功与否的关键因素,而实现这一功能的数据链系统整体性能主要取决于其信道传输的性能。文中主要针对数据链技术中信息传输通道的性能进行研究,给出直接影响整个数据链系统性能的因素,并利用OPNET对Link-16数据链进行传输建模,采用无线信道连接的方式,设计了各种数据链通信环境以检验其性能指标,网络中每个节点的调制方式、带宽、码元传输速率、工作频段设置符合经典Link数据链的标准。仿真结果展示了信道传输的平均延时、错误数据、有效数据和接入节点随时间变化的情况,并给出调制方式对数据量丢包率、平均延时等数据链信道传输性能的影响结果,研究结论对数据链应用的发展具有一定的借鉴意义。

A Comparison of Link Layer Attacks on Wireless Sensor Networks

Wireless sensor networks (WSNs) have many potential applications [1,2] and unique challenges. They usually consist of hundreds or thousands of small sensor nodes such as MICA2, which operate autonomously;conditions such as cost, invisible deployment and many application domains, lead to small size and resource limited sensors [3]. WSNs are susceptible to many types of link layer attacks [1] and most of traditional network security techniques are unusable on WSNs [3];This is due to wireless and shared nature of communication channel, untrusted transmissions, deployment in open environments, unattended nature and limited resources [1]. Therefore security is a vital requirement for these networks;but we have to design a proper security mechanism that attends to WSN’s constraints and requirements. In this paper, we focus on security of WSNs, divide it (the WSNs security) into four categories and will consider them, include: an overview of WSNs, security in WSNs, the threat model on WSNs, a wide variety of WSNs’ link layer attacks and a comparison of them. This work enables us to identify the purpose and capabilities of the attackers;furthermore, the goal and effects of the link layer attacks on WSNs are introduced. Also, this paper discusses known approaches of security detection and defensive mechanisms against the link layer attacks;this would enable IT security managers to manage the link layer attacks of WSNs more effectively.

A NOVEL LINK ADAPTATION SCHEME TO ENHANCE PERFORMANCE OF IEEE 802.11G WIRELESS LAN

A novel link adaptation scheme using linear Auto Regressive (AR) model channel estimation algorithm to enhance the performance of auto rate selection mechanism in IEEE 802.11g is proposed. This scheme can overcome the low efficiency caused by time interval between the time when Received Signal Strength (RSS) is measured and the time when rate is selected. The best rate is selected based on data pay load length, frame retry count and the estimated RSS, which is estimated from recorded RSSs. Simulation results show that the proposed scheme enhances mean throughput performance up to 7%, in saturation state, and up to 24% in finite load state compared with those non-estimation schemes, performance enhancements in average drop rate and average number of transmission attempts per data frame delivery also validate the effectiveness of the proposed scheme.

一种基于动态门限与LMS算法相结合的多径干扰抑制算法

在船舰行驶过程中,信号的传输在岛屿反射与海面散射影响下易产生多径效应,使船舰的无线地空数据接收系统受到影响。为提高接收机的接收性能,首先完成了多径信道的建模,搭建了三径信道模型,并在此模型下,将动态门限法与最小均方(LMS)算法进行改进结合,并用此算法完成了信号处理的研究与仿真。仿真结果表明,所提算法优化方案可以提高在此种情况下信号接收系统的准确性。

智能反射面辅助OFDMA云接入网的资源分配方法

本文研究了智能反射面(IRS)辅助OFDMA(Orthogonal Frequency Division Multiple Access,正交频分多址接入)云无线接入网(C-RAN)的下行链路传输系统,其中基带处理单元(BBU)池通过多个远端射频头(RRH)与多个用户进行通信.RRH到用户的接入链路采用OFDMA接入技术.对于BBU池到RRH,采用无线前传链路,并且部署多个IRS以增强链路传输能力.在BBU池和每个RRH发射功率约束下,本文提出通过联合优化前传链路和接入链路资源配置使下行用户和速率最大化.由于该资源配置问题是非凸的,首先采用连续凸逼近(SCA)对目标以及约束条件进行转换.其次,将转换后的问题拆分成三个子问题来交替性求解.最后,计算机仿真结果显示了所提出的联合资源分配方法与其他基准方案相比具有显著的传输性能增益.

TP-LINK新产品扩建企业无线网络的方案

为了解决企业内用户随时随地高质量上网的问题,提出一种用TP-LINK新产品扩建企业无线网络的方案。首先简述了无线局域网IEEE 802.11系列标准和主要设备,然后对某企业环境及其园区有线网络的拓扑结构进行分析,在企业现有有线网络的基础上,采用了基于TPLINK新产品的Fit AP+AC组网技术。实践证明该方案增强了企业网络信号的稳定性、提高了传输速率、增加了覆盖范围和带机量,满足了企业内移动用户高质量的上网要求。

基于拓扑优化和链路感知的无线体域网路由协议

为解决无线体域网(Wireless Body Area Networks,WBAN)在人体运动过程中网络拓扑结构频繁变化导致链路质量和WBAN性能下降等问题,首先根据人体结构对WBAN网络拓扑进行优化,通过添加中继节点建立WBAN主干网,提供节点和hub之间相对稳定的链接,然后提出了适用于WBAN拓扑优化后的路由策略(Routing Protocol Based on Topology Optimization and Link Awareness,R-TOLA)。R-TOLA综合了链路质量感知和代价函数,通过调整主干网中继和节点中继获得最优化路径。仿真实验表明,基于拓扑结构优化和链路感知的R-TOLA协议和其他路由协议相比,在人体拓扑网络结构频繁变化的环境下具有网络生存时间更长、吞吐量更大等优势。

基于REPBR跳数效用转发的改进路由算法

针对基于压力的水下无线传感器网络路由协议数据包传输路径距离过长、能量消耗不均衡等问题,提出一种基于REPBR跳数效用转发的改进路由算法。采用一种效用函数策略即加入剩余能量、节点间的跳数和链路质量3种因子解决能量消耗不均衡的问题,引入最小跳数算法获取节点到sink节点的跳数值,在数据包转发阶段综合比较路由效益选择最佳转发节点。仿真结果表明,改进后算法相比REPBR、EEDBR、DBR有较小的网络时延,提升了数据包的转发效率,提高了网络性能。

多层级方式下工业物联网5G网络资源分配算法

当前工业物联网中5G无线通信网络链路资源分配节点的设置形式多为目标式,现有的线性化、单层级链路资源分配算法在目标寻优过程中,未考虑不同层级间交叉链路权重分配合理性,网络资源分配效率较低。设计一种面向工业物联网的5G无线通信网络链路资源多层级分配算法。根据当前复杂分配需求及标准的变化,设置基础性链路分配指标,采用多层级的方式,提高链路资源分配的效率。布设多层级资源采集节点,以此为基础,设计自适应交叉链路资源分配结构,结合KM算法,构建工业物联网下链路资源分配模型。采用多点协作的方式来实现资源分配处理。测试结果表明:所设计的链路资源分配算法的分配率均可以达到80%以上,说明在多层级算法的辅助与支持下,链路资源分配效果佳,误差可控,具有实际的应用价值。

双链路通信在露天矿山无人驾驶通信系统中的应用

信息时代给矿山行业带来了新的发展契机,露天矿山智慧化成为发展的必然趋势,无人驾驶作为智慧矿山的重要组成部分之一,为露天矿山生产提供强有力的支撑。在露天矿山无人驾驶场景中,确保通信的可靠性是重中之重,如果网络通信出现问题,则会对无人驾驶车辆的运行造成影响。因此,提升矿山网络通信的可靠性尤为必要,矿山企业可合理应用双链路通信技术,为无人驾驶提供通信保障。基于此,文章从露天矿山无人驾驶通信需求分析入手,论述了双链路通信技术在露天矿山无人驾驶通信系统中的应用。

A Wireless LAN Bridging Solution Based on Campus Network

This paper presents a creative wireless LAN (WLAN) bridging solution, concentrating on the overall realization of a well designed interconnection. This solution integrates effective traffic insulation, intended access control, and required address translation without interfering with the vested interest of internet service provider (ISP). The specific solution can be widely applied on the campus-dorm (off campus)-ISP internetworking mode, where it is hard to implement wired link between campus network and dorm network in terms of cost and existing environmental constraints.

基于ZigBee Light Link的楼宇照明系统设计

传统的楼宇照明系统大部分采取有线网络,存在安装不易,灵活性低,能源消耗大等问题。针对该问题设计了一种基于ZigBee Light Link的楼宇照明系统。系统由智能灯、遥控器、无线网关、监控中心、查询控制器等五部分构成。其中,智能灯与遥控器和无线网关的连接符合ZigBee Light Link标准,无线网关与监控中心通过有线方式连接,监控中心通过以太网或WiFi与查询控制器连接。该系统能对整个楼宇的照明进行综合统一管理,实现节约能源、安全稳定、舒适便捷的楼宇照明系统。

RLINK:一种真实的无线传感器网络链路仿真模型(英文)

在网络仿真中,链路模型的精确性对仿真结果的真实性有着重要影响。基于在无线传感器网络实验中观察到的链路的核心特殊性质——不等向连通性,提出了一个真实的链路仿真模型RLINK.通过对不等向连通性的三个因素进行分析建模,即由遮蔽效应引起的路径衰减的差异、节点硬件的校准差异和天线的方向性差异,该模型实现了无线传感器网络链路的精确模拟。以链路不对称性的累积分布和算数平均值为指标,对比实验和仿真中获得的有关链路特性的统计数据,两者的一致性验证了RLINK的精确性。

Benchmarking the Robustness of Cellular Up-Links in Automatic Weather Station Networks

We present a problem for benchmarking the robustness of cellular up-links, in an automatic weather station (AWS) testbed. Based on the problem, we conduct a small-scale measurement study of robustness, where the AWS is equipped with four (4) cellular modems for weather data delivery. The effectiveness of up-links is challenging because of overlapping spatial-temporal factors such as the presence of good reflectors that lead to multi-path effects, interference, network load or other reasons. We argue that, there is a strong need for independent assessments of their robustness, to perform end-to-end network measurement. However, it is yet difficult to go from a particular measurement to an assessment of the entire network. We extensively measure the variability of Radio Signal Strength (RSSI) as link metric on the cellular modems. The RSSI is one of the important link metrics that can determine the robustness of received RF signals, and explore how they differed from one another at a particular location and instant time. We also apply the statistical analysis that quantifies the level of stability by considering the robustness, referring short-term variation, and determines good up-link in comparison to weak one. The results show that the robustness of cellular up-links exists for an unpredictable period of time and lower than one could hope. More than 50% of up-links are intermittent. Therefore, we plan to extend our work by exploring RSSI thresholds, to develop a classification scheme supporting a decision whether a link is either intermittent or not. This will help in normalizing the level of stability, to design the RSSI estimation metric for the robust routing protocol in weather data networks.

S^3 LQA:A Link Quality Assessment Metric for WSNs Based on Symbol Error and Received Signal Strengt

With the rapid evolution of WSNs technology,it is very important to evaluate link quality quickly and accurately,so that the routing protocols can take relevant strategies in time to keep the entire network working steadily and efficiently. However,the issue of improving link quality assessment methods on physical layer is still open to research. To tackle this issue,a novel link quality assessment metric called S 3 LQA is proposed,which estimates the link quality of wireless sensor networks by CC2420 wireless radio frequency transceiver principles and free space propagation theory. The metric adopts both complete and incomplete packages to improve the evaluation performance effectively based on IEEE802. 15. 4 frame format and DSSS-O-QPSK mechanism. The experimental results show that the proposed method can improve energy cost and achieves better real-timing performance than traditional counting-based ( PRR) link quality assessment metric.