WLAN中吞吐量异构下最小竞争窗口自适应算法

随着移动设备的增多,基于802.11协议的 WLAN系统已经被越来越广泛地使用。由于802.11协议是基于吞吐量相等的设计模式,在这种模式下所有的用户(包括AP)的吞吐量都相等。但是在实际的WLAN系统中,下行吞吐量往往大于上行吞吐量,因此 WLAN设计模式在现实应用中会阻塞下行数据包的传输,上下行吞吐量异构已经是需要解决的一个重要问题。文中提出了一种自适应调节 AP和 STA的最小退避窗口的算法,解决了上下行流量异构问题。     

电力物联网立体异构通信网络协同编排技术研究

采用空-天-地协同的立体通信架构可满足电力物联网广覆盖、大连接的通信需求，但多层异构的通信网络存在结构复杂、节点分散、运维困难等问题。基于SDN（软件定义网络）控制逻辑集中的理念，提出了基于协同编排系统的电力物联网立体异构通信网络协同控制方案。开展了协同编排系统的设计需求分析并完成其功能设计。针对协同编排系统的核心功能需求，提出了改进的基于Q学习的流量调度方法。仿真结果表明，所提方法可提升异构通信网络的流量吞吐能力和负载均衡能力。     

UMTS与WLAN融合的安全问题

第3代合作伙伴计划(3GPP)制定的UMTS与WLAN互联方案可以实现UMTS与WLAN的优势互补,既能提供3 G网络的全球覆盖、基础设施、漫游和计费等,又能实现WLAN的低成本和高数据率。通过对UMTS与WLAN安全机制的分析,详细说明了互联网络安全机制EAP-AKA的工作流程,在WLAN用户侧使用IEEE802.1x协议进行认证存在着假冒AP等安全隐患,文章提出采用双向认证的方式来健全互联网络的安全机制,使互联网络可以提供更加完善、安全的服务。     

一种降低信息反馈的分布式MIMO系统下行波束成形

分布式多输入多输出（MIMO）系统可以利用不同基站的多天线进行空分复用,使系统的容量和性能得到提高,但是在闭环的传输过程中需要向用户反馈解码矩阵,消耗了系统的资源。提出了一种利用对用户信道矩阵斜投影的预编码方法,可以降低基站到移动用户的信息反馈量,并且有效地消除了多用户间的共信道干扰,与迫零的预编码方法相比,可以使系统的误比特率性能和系统的容量得到改善。仿真实验验证了所提方法的有效性。     

计及需求侧响应的光伏微网群与主动配电网双层优化

针对光伏微网群在用电高峰或光伏出力不足时段出现的电能短缺问题,提出一种计及需求侧响应的光伏微网群与主动配电网双层协调优化调度策略.下层微网群根据不同类型微网用户的用电特性,基于分布式理论采用微电网调节成本一致性协调算法,优化出各微网的功率调节方案.上层是以系统网络损耗最小为优化目标、以联络线功率为约束的配电网最优潮流模型.最后以城镇光伏微网群与改进的IEEE-33节点配电网系统作为算例验证策略的可行性,仿真结果表明所提调度策略能使并入ADN系统的微网群和ADN系统双方都具有更好的经济性.     

基于数据驱动分布式鲁棒的热-电-气综合能源系统日前经济调度优化

部署综合能源系统的微网能够实现风电与多种能源的能量互济,进而提升能源的综合利用率.然而风电自身的不确定性为综合能源系统的日前经济调度方案带来了诸多挑战.为应对风电的不确定性,首先构建了热-电-气综合能源系统两阶段日前经济调度模型,其次利用数据驱动分布式鲁棒方法刻画了风电的不确定性,然后引入对偶理论、大M法进一步将非线性的第二阶段经济调度模型转换为易于求解的线性优化模型,最终采用列约束生成算法进行迭代求解.算例证明,相比于传统模型,所提模型能够实现16.9％的经济性提升;相比于鲁棒优化方法,所提方法能够实现经济性提升4％.     

5G-V2X辅助下基于站点区域类型的城市充电站规划方法

5G技术发展使用户能够通过车联网和V2X（vehicle to everything）技术快速获取周围物理环境的信息。车辆、电网运营商等也能根据路网信息进行更好的资源分配与调度,从而促进现代化智慧交通、智慧城市等发展战略的实现。考虑到现代化城市不同区域承担着不同功能,在车辆停靠、电网容量、土地约束、成本价格等方面具有不同特征,为优化充电站部署,建立了V2X辅助下城市区域特征差异充电站模型。考虑实际情况,引入M/M/S/K排队模型和用户充电决策模型对用户行为进行刻画。进一步建立优化模型,在用地面积、电网容量以及服务需求的约束下,通过充电站点选择和充电桩部署,最大化运营商收益。为求解该问题,设计了一种基于站点容量和用户充电行为的充电站网络规划方法,首先求解给定站点的最优充电桩部署数目,然后对候选站点进行筛选聚合实现充电站网络优化。仿真验证了所提优化方法的有效性,所提充电站网络优化方法能够有效提高站点内充电桩利用率,减少运营商建设成本,提升运营商整体盈利。     

基于用户出行模拟的电动汽车快充站负荷预测及其优化调度

电动汽车作为一种新型交通工具,其充放电优化问题得到越来越广泛的关注。论文提出一种基于用户出行模拟的电动汽车光储充一体式直流快充站优化调度方案。首先结合用户出行链概念,基于城市道路网络和改进的路阻函数模型,运用实时路径搜索算法和基于模糊理论的用户充电方式选择方法对一天内城市电动汽车充电负荷的时空分布进行预测;然后以预测结果为基础,以用户“充电贴合度”指标最大的原则将区域充电负荷落实到建设在特定节点处的充电站,接着以站内综合运行成本最小为目标,在满足设备功率、用户出行需求和储能电池状态等约束的条件下,构建优化调度模型。最后将优化方案与仅需满足设备功率平衡且电动汽车用户以额定功率随到随充的常规调度方案进行比较,结果显示,论文所提优化调度方案能够较大限度地降低充电站的运行成本,具有推广应用价值。     

基于N-x不确定集的含可中断负荷鲁棒优化调度

可中断用户响应的不确定性会使电力公司面临调度成本不确定以及负荷削减量不足等风险,且不同用户违约风险具有差异性。针对用户响应调度指令概率不同的问题,在基本可中断合同的基础上引入保险合同,引导用户选择最贴近其真实可靠性水平的保单信誉度。以用户保单信誉度为基础,定义故障概率参数,构建基于用户响应概率的N-x不确定集,建立计及用户不确定性的机组与可中断负荷联合调度模型,并通过仿真验证所提方法的有效性。算例分析结果表明,所提N-x不确定集充分考虑可中断用户信誉度的影响,仅考虑发生概率高于设定值的故障情况,运行结果更符合实际。     

风-火-水-储-气联合优化调度策略

针对电力系统因调节能力不足而造成弃风等问题,构建多源并存的电力系统内风-火-水-储-气联合优化调度模型,并给出模型的求解方法。该模型将常规机组中的灵活电源包括燃气、水电与储能系统进行联合建模,考虑联合运行后不同机组间的相互影响,对联合运行时系统消纳清洁能源的能力提升的内在机理进行分析。为求解提出的联合调度模型,对模型线性化之后采用CPLEX调用内点法进行计算。最后用改进的7机39节点系统进行仿真,结果验证了所提模型对于提高系统调节能力、促进风电消纳、优化系统工况的作用。联合调度策略结合实际电力系统中多源并存的现状为应对风电接入问题提供了一种实际可行的调度方案。     

一种基于Ad Hoc网络的节点调度方法

传统的无线Ad Hoc网络中的MAC协议基本上都是采用全向天线,尽管采用全向天线能带来许多的优点,但是它的一些问题带来了难题,例如隐藏节点和聋节点问题.为了解决隐藏节点和聋节点问题,减少数据碰撞,提出了一种基于时隙的节点调度方法.通过OPNET仿真,该调度方法提高了吞吐量,减少了端到端的时延,相比WLAN和MMAC而言...     

A high‐speed MIMO FFT processor with full hardware utilization

The conventional way to design multi‐input‐multi‐output (MIMO) fast Fourier transform (FFT) processors for MIMO‐orthogonal frequency division multiplexing systems is to adopt a parallel architecture which uses as many single‐input‐single‐output FFT processors as the number of transmit/receive antennas. These MIMO FFT processors can provide high throughput, but they perform with low hardware utilization when there are not all input sequences available. In this paper, we propose a high‐speed MIMO FFT processor which can work efficiently with high throughput and full hardware utilization for variable 1 to 4 input sequences. Our MIMO FFT processor is designed by reordering and distributing data sequences to all data paths and is constructed by some novel modules. Being synthesized by using UMC 0.18‐μm process demonstrates that our 64‐point 4 × 4 FFT can achieve high throughput with full hardware utilization and perform correctly up to 62.25 MHz with low power consumption for variable 1 to 4 input sequences.     

A 3.6‐mW 6‐GHz current‐reuse VCO‐buffer with improved load drivability in 65‐nm CMOS

A new current‐reuse voltage‐controlled oscillator (VCO)‐buffer with enhanced load drivability is proposed. It incorporates a PMOS‐based source follower stacked atop a NMOS‐based LC VCO to share the bias current, while preventing the voltage stress at any oscillation node from exceeding the 1.2‐V technology voltage limit. Also, ac‐coupling networks are avoided between the VCO and buffer, improving the Q of the LC tank while minimizing parasitics. With internal buffering, the VCO can directly drive up a 50‐Ω load for testing, or to withstand a large capacitive load in on‐chip local oscillator distribution, particularly suitable for multi‐band MIMO WLAN radios . The fabricated VCO‐buffer in 65‐nm CMOS measures 13.8% tuning range from 5.64 to 6.4 GHz, consumes 3.6 mW at 1.2 V and exhibits ?108.84 dBc/Hz phase noise at 1‐MHz offset. Copyright © 2013 John Wiley & Sons, Ltd.     

Neutralizing interferences in two‐hop amplify‐and‐forward MIMO relay systems

In this paper, we present the interference neutralization technique for two‐hop multiple‐input multiple‐output (MIMO) relay systems. It enables multiple MIMO transmitters (sources) to simultaneously transmit independent data streams to their MIMO receivers (destinations) without mutual interferences, thereby improving spectral efficiency of the systems. To neutralize the mutual interferences using multiple amplify‐and‐forward (AF) MIMO relays, we establish the sufficient condition for the antenna configuration in the MIMO relay networks, and provide a filter design technique for the AF MIMO relays. The proposed method increases sum rates of the systems linearly with the number of transmitters participating in simultaneous transmission. To improve the sum rates further, this method is combined with transmit power allocation using the water‐filling algorithm. In addition, it is shown that by employing the minimum number of relays required to meet the sufficient condition, the system cost for the proposed method can be reduced without compromising the sum rate performance severely. Finally, simulation results successfully demonstrate that by exploiting radio resources such as frequency and time efficiently, the proposed method achieves a higher sum rate than the existing techniques based on interference avoidance. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A scheduled controller design of congestion control considering network resource constraints

In this paper, we consider a dynamical model of computer networks and derive a synthesis method for congestion control. First, we present a model of TCP/AQM (Transmission Control Protocol/Active Queue Management) as a dynamical model of computer networks. The dynamical model of TCP/AQM networks consists of models of TCP window size, queue length, and AQM mechanisms. Second, we propose to describe the dynamical model of TCP/AQM networks as linear systems with self‐scheduling parameters, which also depend on information delay. Here we focus on the constraints on the maximum queue length and TCP window size, which are the network resources in TCP/AQM networks. We derive TCP/AQM networks as the LPV system (linear parameter varying system) with information delay and self‐scheduling parameter. We design a memoryless state feedback controller of the LPV system based on a gain‐scheduling method. Finally, the effectiveness of the proposed method is evaluated by using MATLAB and the well‐known ns‐2 simulator (Network Simulator Version 2). © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 149(1): 61–68, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10341     

基于WLAN和PDA两医院网络应用平台设计与开发

随着相关技术和产品日益成熟，无线局域网(WLAN)已倍受各行业青睐．在医院信息化工程(E-Hospital)中融人WLAN，是将医院传统医疗方式转变成基于无线移动网络、以临床和管理数据为中心的现代医疗方式的有效途径，在分析WLAN技术发展现状的基础上，结合医院行业特点提出了一套WLAN和临床信息系统整体设计方案．     

无线局域网协议及性能分析

文中介绍无线局域网标准IEEE802.11及它的扩展标准,分析不同环境下无线局域网的吞吐量性能.     

无线网络中基于信道状态预测的调度算法

在蜂窝无线网络下行链路的资源调度中,无线信道的时变特点对网络的吞吐量和用户之间的公平性有很大的影响.为了达到高数据吞吐量并且同时保证用户服务质量QoS的目的,本文提出一种基于信道预测的调度算法PSUCS,该算法通过当前时隙的信道状态,预测下一个时隙的信道状态,并利用该信息,将资源调度的问题描述成求解效用函数最大的优化模型和最优的调度策略.仿真结果表明,该算法在保证公平性的前提下,有效提高了无线网络下行链路吞吐量.     

Joint optimization in MIMO multiple relay channels

The joint optimization of cooperative relays in a multiple-input multiple-output (MIMO) multiple relay aided communication system is discussed in this article. A simple linear optimization solution is designed and a multi-user scheduling algorithm is proposed. The new algorithm chooses users with larger cooperation diversity gains from the waiting list to serve; it can reduce inter-user interference and maintain space diversity caused by parallel transmission of multiple relays, and achieve higher system throughput. __________ Translated from Journal on Communications, 2008, 29(3): 40–46 [译自: 通信学报]     

Experimental verification of massive antenna systems employing parallelogram planar arrays

This paper experimentally verifies how the parallelogram planar array (PPA) can improve the space division multiplexing (SDM) performance of multiuser massive multiple‐input multiple‐output (MIMO) in line‐of‐sight (LOS) channels. PPA can reduce the spatial channel correlation (inter‐user correlation) without any increase in processing load. Channel state information (CSI) of up to 94 antenna elements is measured with simplified test equipment in an outdoor propagation environment. Assessment of the measured CSI confirms the effectiveness of PPA in terms of reduced spatial channel correlation and its higher order SDM ability with simplified user scheduling.