基于PER-DDPG算法的城市轨道交通越区切换研究

针对传统IEEE802.11越区切换方式存在较高的切换延时以及乒乓切换等问题,提出深度强化学习(Deep Q-Network,DQN)越区切换算法。通过对列车运行的特征状态信息进行提取输入,考虑列车运行速度及场强、切换阈值等动态信息构建越区切换模型。同时针对算法时间成本复杂度及稳定性,采用优先经验回放深度确定性策略梯度(Prioritized Experience Replay-Deep Deterministic Policy Gradient,PER-DDPG)算法,将列车状态空间信息传输至PER-DDPG网络中进行优化分析。结果表明基于PER-DDPG算法优化后的列车越区切换模型使用该算法时间计算成本降低,数据包传输延时约降低55%。

IEEE标准接地网设计及计算示例

随着“一带一路”的推进,国外设计项目日益增多,大部分项目技术合同对接地设计均要求满足IEEE标准。本文通过印度尼西亚某燃煤电站主接地网的设计计算示例,对按照IEEE接地标准设计的接地网设计思路进行简述。

Wi-Fi 7技术与产业发展探讨

Wi-Fi网络已成为人们日常生活中不可或缺的一部分。家庭场景中手机、平板电脑、摄像头、智能家电等终端均连接到Wi-Fi网络;商场、机场、酒店等公共场所处处可见提供定位、导航和移动支付等业务的免费Wi-Fi网络;在企业园区内,用户通过Wi-Fi网络实现移动协同办公。目前Wi-Fi技术已经演进到第七代,即遵循IEEE802.11be标准的Wi-Fi 7。Wi-Fi7的设计目标是利用现有的2.4GHZ、5GHz以及新增的6GHZ频段,兼顾高性能和高可靠两方面特性,使得Wi-Fi速率达到30Gbit/s以上,时延降低到5ms以下。基于时延、速率和容量等方面的优势,Wi-Fi7有望应用于扩展现实(XR)、元宇宙、社交游戏和边缘计算等高速率、超低时延应用场景。

一种适用于Chiplet测试的通用测试访问端口控制器电路设计

在后摩尔时代里,Chiplet是当前最火热的异构芯片集成技术,具有复杂的多芯粒堆叠结构等特点。为了解决Chiplet在不同堆叠结构中的芯粒绑定后测试问题,基于IEEE 1838标准协议,该文提出一种适用于Chiplet测试的通用测试访问端口控制器(UTAPC)电路。该电路在传统测试访问端口(TAP)控制器的基础上设计了Chiplet专用有限状态机(CDFSM),增加了Chiplet测试路径配置寄存器和Chiplet测试接口电路。在CDFSM产生的配置寄存器控制信号作用下,通过Chiplet测试路径配置寄存器输出的配置信号来控制Chiplet测试接口电路以设置Chiplet的有效测试路径,实现跨层访问芯粒。仿真结果表明,所提UTAPC电路适用于任意堆叠结构的Chiplet的可测试性设计,可以有效地选择芯粒的测试,还节省了测试端口和测试时间资源并提升了测试效率。

基于权值构建数据导频的V2V信道估计算法

针对IEEE 802.11p协议中导频数量不足无法准确跟踪车联网信道快速变化的问题,本文提出了一种基于时频域相关性构建数据导频、加权平滑重构判决策略的信道估计算法。该算法在不改变IEEE 802.11p协议标准导频结构的前提下,有效利用频域相邻子载波间以及时域相邻正交频分复用符号间的强相关性构建数据导频,引入权值因子对前后时刻信道估计值动态时域更新,结合频域平均重构数据导频构建算法的判决策略。仿真结果表明:在3种不同车-车(vehicle-to-vehicle,V2V)通信场景下,本文提出的算法在误码率和均方根误差方面优于时频平均、数据导频构建等算法。

基于IEEE 802.11ad多帧相关测速算法

波形设计是实现通信感知一体化关键技术之一,有利于缓解频谱竞争压力、减少资源浪费。该文提出一种在车对万物互联(V2X)场景下基于IEEE 802.11ad无线局域网波形的测速算法。首先基于物理层帧结构中前导良好的目标感知特性对接收多帧信号的前导做不同移位的相关运算,将多普勒频偏估计转换为线性回归斜率估计得到多普勒估计值用以测速;其次提出相位补偿方案,解决由相位模糊导致的测速范围受限问题。仿真结果表明,在单目标视距场景下所提算法可实现厘米级测速精度,且相较于目前同类型算法具有更低测速误差。

基于自适应跳跃学习网络的OFDM信道预测方法

信道预测是支撑变电站等电力物联网通信系统自适应传输的重要技术。为了解决过期信道状态信息降低通信系统自适应传输性能的问题,提出了一种基于自适应跳跃学习网络的信道状态信息预测方法。该方法主要包括递归微调算法和混合惩戒网络两部分。其中,前者主要用于微调学习网络的随机输入权重矩阵,后者主要通过两层惩戒网络来解决输出权重矩阵的病态解问题。由于具有oracle属性,自适应跳跃学习网络不仅具有良好的泛化能力,还可以生成稀疏性输出权重矩阵。仿真结果表明,自适应跳跃学习网络在IEEE802.11ah协议的正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)通信系统中具有良好的单步预测性能和多步预测性能。

International Standardization of Blockchain and Distributed Ledger Technology:Overlaps,Gaps and Challenges

As one of the most concerned digital technologies in recent years,blockchain and distributed ledger technology are an important driving force for a new round of technological development.It is currently in the process of accelerating its evolution and maturity,and has gradually integrated with other digital technologies.It has been applied in many industries,providing decentralized solutions for various industries,realizing innovative storage models,and building a new trust system.As blockchain technology is officially incorporated into China’s new information infrastructure category,the application fields of blockchain have expanded rapidly,gradually extending from the financial field and government affairs to other fields in the real economy.At the same time,with the continuous development of the globalized economy,blockchain technology will also have a profound impact on international technological and economic development.Therefore,for the healthy and orderly development and real implementation of the blockchain industry,standardize the application of blockchain,effectively break through the cognitive and technical barriers between different countries,industries and systems on a global scale,prevent application risks,the development of the global blockchain industry needs standardization basis,which is particularly important and urgent.A sound standard system is an important key to the successful development of technology,and formulating the right standard at the right time for technology development helps ensure the ease of use and interoperability of the technology.From the perspective of international standardization,this article first introduces the general situation of ISO,ITU-T,IEEE,W3C and other international standardization organizations,and sorts out the status quo of the blockchain standardization working groups of mainstream international standardization organizations.All blockchain-related standards under development have been analyzed for the characteristics of international blockchain technology standards and industry application standards.Through data analysis,the overlaps,differences and conflicts in the field of international blockchain standard formulation are sorted out,and suggestions for blockchain standardization work in the application and development of blockchain technology standardization by international organizations and industries are put forward.The plans and layouts of future international standards are summarized to help the development of the international standardization of blockchain.

电网稳定控制技术国际标准现状与发展

电力系统是实现“双碳”目标的重要主战场之一,其安全和稳定应首先予以保证。稳定控制技术是保障电网安全稳定的重要关键技术,已在许多国家和地区电网获得规模化工程应用,标准化是提升和保障其工程可靠性的有效手段。针对稳定控制技术国际标准化大幅滞后于电网生产运行的问题,溯源稳定控制技术历史及发展,研究分析国内外预防控制、事件触发控制、响应驱动控制以及恢复控制等4种类型稳定控制的标准化进展及工程应用情况,重点规划了事件触发控制和响应驱动控制方向的国际标准技术体系,并提出近期可开展的具体标准技术。该文的工作为IEC下一步制修订稳定控制技术标准奠定基础。

高速公路V2V通信中C-V2X和IEEE802.11p通信协议的比较

在概述C-V2X和IEEE802.11p通信技术发展概况及特征的基础上,依托OMNET++仿真平台,采用Veins和SUMO联合仿真技术建立起高速公路通信仿真场景,并进行C-V2X和IEEE802.11p通信协议丢包率和端到端时延等参数值的计算分析与性能比测。结果表明,C-V2X通信技术是高速公路新型信息基础设施建设的重要部分,因具备高可靠、高传输效率、低时延等优势,而成为国际主流公路通信标准;C-V2X和IEEE802.11p通信技术在安全应用时延方面均满足要求,但C-V2X在丢包率方面比IEEE802.11p更优。

Deep Reinforcement Learning Based Spectrum Prediction for Bursty Bands

Spectrum prediction plays an important role for the secondary user(SU)to utilize the shared spectrum resources.However,currently utilized prediction methods are not well applied to spectrum with high burstiness,as parameters of prediction models cannot be adjusted properly.This paper studies the prediction problem of bursty bands.Specifically,we first collect real Wi Fi transmission data in 2.4GHz Industrial,Scientific,Medical(ISM)band which is considered to have bursty characteristics.Feature analysis of the data indicates that the spectrum occupancy law of the data is time-variant,which suggests that the performance of commonly used single prediction model could be restricted.Considering that the match between diverse spectrum states and multiple prediction models may essentially improve the prediction performance,we then propose a deep-reinforcement learning based multilayer perceptron(DRL-MLP)method to address this matching problem.The state space of the method is composed of feature vectors,and each of the vectors contains multi-dimensional feature values.Meanwhile,the action space consists of several multilayer perceptrons(MLPs)that are trained on the basis of multiple classified data sets.We finally conduct experiments with the collected real data and simulations with generated data to verify the performance of the proposed method.The results demonstrate that the proposed method significantly outperforms the stateof-the-art methods in terms of the prediction accuracy.

A renewal theory based performance and configuration framework of the IEEE 802.11ah RAW mechanism

IEEE 802.11ah is a new Wi-Fi standard for sub-1Ghz communications,aiming to address the challenges of the Internet of Things(IoT).Significant changes in the legacy 802.11 standards have been proposed to improve the network performance in high contention scenarios,the most important of which is the Restricted Access Window(RAW)mechanism.This mechanism promises to increase the throughput and energy efficiency by dividing stations into different groups.Under this scheme,only the stations belonging to the same group may access the channel,which reduces the collision probability in dense scenarios.However,the standard does not define the RAW grouping strategy.In this paper,we develop a new mathematical model based on the renewal theory,which allows for tracking the number of transmissions within the limited RAW slot contention period defined by the standard.We then analyze and evaluate the performance of RAW mechanism.We also introduce a grouping scheme to organize the stations and channel access time into different groups within the RAW.Furthermore,we propose an algorithm to derive the RAW configuration parameters of a throughput maximizing grouping scheme.We additionally explore the impact of channel errors on the contention within the time-limited RAW slot and the overall RAW optimal configuration.The presented analytical framework can be applied to many other Wi-Fi standards that integrate periodic channel reservations.Extensive simulations using the MATLAB software validate the analytical model and prove the effectiveness of the proposed RAW configuration scheme.

Reinforcement Learning-Based Handover Scheme with Neighbor Beacon Frame Transmission

Mobility support to change the connection from one access point(AP)to the next(i.e.,handover)becomes one of the important issues in IEEE 802.11 wireless local area networks(WLANs).During handover,the channel scanning procedure,which aims to collect neighbor AP(NAP)information on all available channels,accounts for most of the delay time.To reduce the channel scanning procedure,a neighbor beacon frame transmission scheme(N-BTS)was proposed for a seamless handover.N-BTS can provide a seamless handover by removing the channel scanning procedure.However,N-BTS always requires operating overhead even if there are few mobile stations(MSs)for the handover.Therefore,this paper proposes a reinforcement learning-based handover scheme with neighbor beacon frame transmission(MAN-BTS)to properly consider the use of N-BTS.The optimization equation is defined to maximize the expected reward tofind the optimal policy and is solved using Q-learning.Simulation results show that the proposed scheme outperforms the comparison schemes in terms of the expected reward.

基于IEEE 802.11be标准的高阶调制信号的解调算法分析

针对IEEE 802.11be标准采用的4096QAM高阶调制信号,提出了一种基于data字段的Wi-Fi信号解调方法,设计了一套完整的Wi-Fi信号解调算法流程。首先,基于前导序列进行帧同步,再利用前导序列中的L-LTF进行载波频偏估计与补偿;其次,根据data字段确定调制类型及空分复用类型,进行信道估计和相位补偿;最后,对补偿后的数据进行解调处理,获得信号质量结果。经过采集数据实验,验证了该算法可有效实现IEEE 802.11be标准Wi-Fi信号的解调。

连接物联网:Wi-Fi HaLow与蓝牙对比

如今,物联网几乎与每个行业都息息相关,是IT类增长最快的领域之一。去年,物联网的消费高达3003亿美元,预计到2026年将达到6505亿美元。随着物联网成为成为我们生活中不可或缺的一部分,企业必须了解如何支持这个随新时代而来的不断增长的连接需求。并非所有的无线连接都是相同的首先要注意的是,并非所有的无线连接都是相同的。Wi-Fi HaLow融合了IEEE802.11ah,是IEEE 802.11系列中最新的Wi-Fi协议之一,专为满足物联网环境的独特需求而设计1。

Wi-Fi 7关键技术研究综述

随着人工智能、大数据、物联网等技术的高速发展,4K/8K视频、在线大型游戏、虚拟现实(Virtual Reality,VR)和远程办公等应用程序也应运而生。然而,现有的Wi-Fi 6标准难以满足其高吞吐量和低时延的网络需求。因此,IEEE将发布下一代无线局域网(Wireless Local Area Network,WLAN)标准IEEE 802.11be,也称为Wi-Fi 7。文章重点介绍和分析了Wi-Fi 7的技术特点和应用场景,最后总结和展望了Wi-Fi 7的研究方向和潜在发展。

C-V2X和IEEE802.11p协议下高速公路V2V通信技术比较

在概述C-V2X和IEEE802.11p通信协议优劣势的基础上,依托OMNET++和SUMO联合仿真平台,对不同车辆数目及运行速度影响通信性能的问题展开分析,并对C-V2X和IEEE802.11p通信协议的端到端时延、丢包率等进行了比较研究。结果表明,C-V2X和IEEE802.11p通信协议均能满足高速公路通信安全性方面的时延要求,但C-V2X在丢包率方面明显较优。

智慧城市感知网络非相干检测技术研究

目前智慧城市建设中在有限的频谱资源上无法实现高效可靠的数据传输。文章依据IEEE 802.15.4c标准中MPSK接收器对成本和复杂度的设计要求,提出基于频偏估计的MPSK信号多符号非相干检测新算法。在全面考虑载波频率偏移(Carrier Frequency Offset,CFO)、载波相位偏移(Carrier Phase Offset,CPO)、乘性衰落和加性噪声的基础上,利用前导符和伪随机噪声(Pseudo-random Noise,PN)序列构造新度量函数估计以补偿频偏,并借助频偏补偿后的接收信号和PN序列推导完全形式的检测算法。低复杂度多符号检测(Multiple Symbol Detection,MSD)算法以完全形式检测分析为基础,利用每个符号局部最大度量和次大度量有效降低检测搜索空间和判决统计量计算次数,易于实现。最后,通过实验对所提算法进行仿真,结果表明系统检测性能和鲁棒性均显著提高。

IEEE 802.11无线局域网标准研究

介绍了IEEE 802.11全系列标准,研究了IEEE 802.11系列各标准的发展轨迹和相互关系,建立了该系列标准的层次模型。研究并分析了IEEE 802.11、IEEE 802.11a、IEEE 802.11b、IEEE 802.11g和IEEE 802.11n这几种常见标准,并对相应物理层和媒质访问控制层的关键技术作了重点分析。

基于IEEE 802.11的长距离无线Mesh网络

基于IEEE 802.11的长距离无线Mesh网络(LDmesh)的单跳链路长度在几十到上百公里,具有带宽高、成本低、覆盖广等优点,可广泛应用于偏远乡村或人口分布稀疏地区的无线宽带接入等.LDmesh网络是点到点的链路,链路的干扰特性和传输特性与传统无线Mesh网络有显著不同,原有的基于CSMA的MAC协议不再适用,进而影响到上层协议的设计.分析了LDmesh网络的研究进展,从链路性能、MAC协议、路由协议及网络管理等方面深入论述了LDmesh网络面临的挑战和进一步研究方向.