基于WRR的改进型队列调度算法

基于Diffserv(区分服务)体系,研究实现QoS(服务质量)控制的核心技术之一的队列调度技术。基于WRR(加权轮询)队列调度算法,提出新型的改进算法。改进的队列调度算法主要由流量调节器和调度策略两部分构成,将网络上的包按照Diffserv体系分为EF(加速转发)、AF(保证转发)、BE(尽力服务)三种业务类型,对不同的类型采用不同的调度策略。针对高优先级的EF业务直接采用PRI(优先级调度),针对AF业务采用改进后的WRR调度。仿真结果表明,该改进型调度算法在网络资源分配上具有一定的优越性。     

Web集群的区分服务与负载均衡策略研究

该文从区分服务和负载均衡两方面研究Web集群系统,设计并实现了一种支持区分服务的负载均衡集群模型,通过系统辨识和资源最优控制,对后端资源统一调度,动态调整每台后端节点不同优先级业务类的资源配额;同时设计了基于业务类的最大空闲节点优先的负载均衡策略以保证各个后端节点同一业务类资源被公平消耗,从而控制端到端延迟,实现比例延迟保证。经实验验证,无论采用轮询调度、最少连接数调度还是最大空闲节点优先的均衡策略,资源最优控制器均能取得良好的区分效果,扩展实验还表明,相对于轮询调度和最少连接数调度,采用最大空闲节点优先的均衡策略,能够使该集群系统在实现比例延迟保证的同时获得最大的性能优化,整体吞吐量提高了25%,平均延迟降低了33%。     

高速SpaceFibre路由系统设计

为了满足空间多元化数据的高速传输需求,本文对SpaceFibre高速总线网络进行了研究,针对路由网络中的数据转发冲突,提出了一种SpaceFibre路由系统设计方案.其中,配置端口实现了网络参数的实时配置和状态的实时反馈;路由端口实现了基于虚拟通道机制的QoS调度,为不同数据源提供不同服务;路由交换模块中利用全连接结构实现了虚拟网络间的互联,并针对虚拟网络中的数据交换冲突,设计了一种基于优先级等待的动态仲裁算法,能兼顾优先级和等待时间为数据发送提供保障;在路由广播中采用轮询仲裁算法,解决了端口间的广播冲突.最后通过搭建仿真测试平台,对路由进行仿真测试,结果表明设计的SpaceFibre路由能够高效地处理数据转发冲突,并提供QoS数据传输服务,每路接口带宽高达3.125 Gbps.     

MIMO无线通信系统中调度算法分析

对轮询算法、最大载干比算法和比例公平算法三种经典的调度算法进行了深入的研究,并在MIMO系统环境中,对它们的性能进行了计算机仿真。从基本原理和仿真结果两个方面,对上述三种调度算法的公平性和系统吞吐量性能进行了对比分析,证明了轮询算法具有最好的公平性性能,最大载干比算法具有最好的吞吐量性能,比例公平算法则很好的在两者之间取得了一个平衡。     

网络编码调度策略的研究

网络编码是通信领域的一项重大突破,其基本思想是建立在网络信息流的基础之上,通过网络节点对来自不同链路的信息流进行编码处理,使其既能实现传统路由功能,又能实现对信息的编码处理。分析了等速率的网络编码调度策略,并把自适应传输技术应用到网络编码的调度策略,然后通过Matlab仿真分析,验证了自适应的网络编码策略可提高通信系统的网络编码增益、吞吐量和减少数据传输延时方面的贡献。     

LTE系统级仿真的关键技术与研究

以3GPP在技术规范中对LTE系统仿真所提要求为标准,对LTE系统级仿真的整体流程与基本框架进行了概括与分析,介绍了链路级映射的2种方法,在分析各功能模块的基础上搭建了系统级仿真平台,实现了LTE的系统级仿真。以下行调度算法为对象,通过系统级仿真平台对轮询、最大载干比和比例公平这3种经典分组调度算法进行了仿真与分析,为LTE系统级仿真平台的进一步完善和发展提供了理论参考。     

支持优先级与公平策略的队列规程

首先介绍了队列调度算法在流量控制中的关键地位,然后讨论了现有队列调度算法,如基于优先级的调度算法、轮询调度算法与公平队列调度算法,最后提出了一种新的队列规程,该队列规程融合了优先级调度算法与DRR调度算法。在网络正常情况下,不同业务流公平地共享网络带宽,在网络出现拥塞的情况下,高优先级业务流能够抢占带宽,保证其较低的丢包率,并能够实现两种调度算法的快速切换。     

一种SDN中用户群博弈的OpenFlow流调度策略

提出了一种基于用户中心网络的软件定义网络框架,建立了一种基于用户群博弈策略的OpenFlow流调度模型,提取用户群属性及用户最佳体验参数,从用户层面跨层至控制层进行调度,对比了非合作博弈调度与合作博弈调度。仿真结果显示,合作博弈调度的用户群整体满意度最佳,有助于通信运营商实现“用户为王”的理念。     

兼容电力线载波通信的低压集抄研究

文中介绍了一种利用电力线通信(PLC)网络从智能电表(SM)实时采集低压用户用电数据实现低压集抄的有效方法。PLC网络使用现有的电线同时承载数据和电力,然而由于PLC网络中的传输介质不是为高质量数据传输而设计的,因此其网络通信效率是有限的。PLC网络的流量负载受路由算法和智能电表的轮询顺序的显著影响。文中提出了两种基于应用层方法的智能轮询算法。这两种算法的主要思路是通过对嵌入在路由控制消息进行优化以降低三层网络中数据包的数量从而提高基于PLC网络的低压集抄平台的通信效率。仿真实验证明了所提出的算法基于两种常见三层路由协议在PLC网络中能够提高低压集抄平台的自动抄表效率。     

两级优先级控制轮询系统研究

 本文基于区分业务优先级服务的应用需求,提出了两级优先级控制的轮询系统,采用门限服务和完全服务的不同服务策略方式实现了基于优先级的控制.然后,应用马尔可夫链和概率母函数的方法建立了系统模型,并精确解析了系统的平均排队队长和信息分组的平均等待时间关键特性,理论计算和仿真实验的对比分析说明了理论分析与实验的一致性,新的轮询系统实现了优先级的控制并提高了系统性能.     

用遗传算法求解基于高阶累积量的盲均衡问题

将遗传算法引入盲均衡技术领域，详细分析了如何用遗传算法求解基于高阶累积量盲均衡问题，并给出了一种求解算法的具体步骤。该算法不用基于领域知识的规则，具有很强的通用性与鲁棒性。通过计算机仿真验证了该算法的有效性。     

Multiple-access channels with memory with and without framesynchronism

The capacity region of frame-synchronous and frame-asynchronous, discrete, two-user multiple-access channels with finite memory is obtained. Frame synchronism refers to the ability of the transmitters to send their code words in unison. The absence of frame synchronism in memoryless multiple-access channels is known to result in the removal of the convex hull operation from the expression of the capacity region. It is shown that when the channel has memory, frame asynchronism rules out nonstationary inputs to achieve any point in the capacity region, thereby allowing only coding strategies that involve cooperation in the frequency domain but not in the time domain. This restriction drastically reduces the capacity region of some multiple-access channels with memory, and in particular the total capacity of the channel, which is invariant to frame asynchronism for memoryless channels     

一种背面深槽填充P型多晶硅RC-IGBT

提出了一种新型RC-IGBT,在背面阳极处设置了填充重掺杂P型多晶硅的深槽和FOC浮空电极。器件正向导通时,利用重掺杂P型多晶硅与N型衬底的接触电势差,将槽间的N型衬底部分耗尽,增强了阳极PN结的短路电阻,在较短背面阳极尺寸的条件下实现了RC-IGBT在开启过程中不出现电压折回现象。在器件反向开启过程中,空穴电流经过FOC浮空电极流入P型多晶硅,降低了多晶硅与N型衬底之间的势垒,提高了反向二极管的开启速度,降低了开启过程中二极管的过充电压。仿真结果表明,提出的新型RC-IGBT完全消除了电压折回现象,反向电流的均匀性得到了提高。相比于传统RC-IGBT,该新型RC-IGBT的元胞背面尺寸减小了88.89%,关断损耗降低了26.37%,反并联二极管的反向恢复电荷降低了13.12%。     

Spectrum Shaping with Alphabetic Codes with Finite Autocorrelation Sequence

In this paper we consider the problem of recoding binary data into ternary sequences for synchronous baseband data transmission systems. Our major objective is the shaping of the power spectral density of the channel process in order to combat the effects of intersymbol interference caused by the low-frequency cut-off of the channel. This motivates our interest in designing codes whose channel process has small Power in the low frequency range. Based on the MacLaurin expansion of the power density function, we use as a design heuristic the normalized second derivative Δ of the latter. To make computationally manageable the expression of Δ, we restrict ourselves to a class of codes whose autocorrelation sequence contains a finite number of nonzero terms, and present a corresponding code design algorithm. As examples, we exhibit two new codes which in many respects improve over the spectra of corresponding well-known codes.     

Low-power MOS integrated filter with transconductors with spoiltcurrent sources

It is shown that an MOS weak-inversion differential pair can be linearized considerably by replacing the tail current source with a MOSFET biased in the weak-inversion triode region. Calculations show that the transconductance can be kept constant to within +5%/-0% for input voltages up to 130 mV. This linearized differential pair is used in a third-order transconductance-C bandpass filter with 18 Hz and 142 Hz cutoff frequencies, which draws 4.9 nA from a 1.8-V supply. Its dynamic range is 62 dB and its active area is 0.5 mm²     

Terahertz imaging with bow-tie InGaAs-based diode with broken symmetry

A silicon-lens coupled bow-tie InGaAs-based diode with broken symmetry is demonstrated for terahertz imaging applications below 1 THz at room temperature. Transient features and the dynamic range of the bow-tie InGaAs-based sensor are explored experimentally, proving the possibility to use the device in real-time imaging systems. Response time is found to be less than 7 ns, responsivity of 0.1 mA/W, and noise equivalent power of 5.8 nW/radicHz.     

一种给批量汉字加注带有声调拼音的方法

由于汉字存在着多音字的情况,所以给汉字加注带有声调的拼音带来了困难.为了解决这一问题,设计了单字与词语相结合的加注方法.首先构建了带有声调的拼音字典和词典,拼音字典中同一个多音字的拼音按照使用频率进行排放,并且对词典中的词语按照最后一个字进行了索引;然后设计了基于整词二分的二层索引结构,实现了改进的最大逆向分词算法;最后设计了三种实验方案,进行了对比实验.实验结果表明,在没有使用该方法前它的错误率为11%,使用后错误率下降为0.09%.     

Anisotropy of composite materials with inclusion with orientation preference

In this paper, the quasicrystalline model and the differential evolution strategy are applied to analyze the effective electromagnetic properties of composite materials with aligned nonspherical inclusions. The relationship between the effective wave number, volume concentration, direction of wave propagation vector, and aspect ratio of the inclusion particle are numerically studied. It is found that composite materials with small inclusion particles behave like uniaxial material. In addition, we observed general effective anisotropy in composite materials with larger inclusion particles.     

Feedback with carry shift registers synthesis with the Euclidean algorithm

Feedback with carry shift registers (FCSR) were introduced by Klapper and Goresky (1994). They are very similar to classical linear feedback shift registers (LFSR) used in many pseudorandom generators. The main difference is the fact that the elementary additions are not additions modulo 2 but with propagation of carries. The mathematical models for LFSR are equivalently linear recurring sequences over GF(2) or rational series in the set GF(2)[[x]]. For FCSR, the "good" model is the one of rational 2-adic numbers. It is well known, that the series generated by a LFSR can be synthesized by either the Berlekamp-Massey algorithm for binary linear recurring sequences or the extended Euclidean algorithm in the set GF(2)[x] of binary polynomials. Klapper and Goresky (1997) give an algorithm for the FCSR synthesis. This algorithm is similar to those of Berlekamp-Massey and is based on De Weger and Mahler's rational approximation theory. In this correspondence, we prove that it is possible to synthesize the FCSR with the extended Euclidean algorithm in the ring /spl Zopf/ of integers. This algorithm is clearly equivalent to the previous one, however, it is simpler to understand, to implement, and to prove. Our algorithm is still valid in the case of g-adic integers where g is a positive integer. We also give a near-adaptative version of this algorithm.     

从全比特记录到压缩比特记录--数字录像机发展综述

1 引言 在电视节目制作设备中录像机是最基本的设备,从前期拍摄到后期编辑直至播出都要用到,它的质量高低关系重大,所以人们在它上面倾注了大量心血,不断提高记录图像的质量,尤其近几年数字录像机的发展更是异常迅速. 自从1956年由美国的安培公司首创了2英寸、四磁头横向扫描录像机以来,为了满足广播、业务、家用等不同用途,生产了各种不同型号、不同系列的录像机.如1英寸B格式和C格式螺旋扫描广播级录像机.它们的记录方式都是将全电视信号作为一个整体直接调频记录到磁带上.1英寸录像机质量很高,但体积大、价格昂贵.后来人们又研制成功了一系列盒式录像机,如U-matic,β,VHS,S-VHS、8mm,Hi8,这些录像机为了降低成本,减小体积,采用了与1英寸、2英寸完全不同的记录方式,即亮度信号调频,色度信号降频,然后混合在一起,对亮/色信号利用同一磁头记录在同一条磁迹上.这种记录方式称为模拟复合记录方式.