一种分层蜂窝网中基于用户分类的建模分析方法

随着无线网中用户需求的业务量持续增大,且用户具有不同移动性,分层蜂窝结构(HCS)被提出。该文研究一种微小区/宏小区的双层蜂窝结构的网络性能,此系统采用双向溢出策略,呼叫用户根据其速度选择合适的接入层(慢用户接入微小区,快用户接入宏小区)。该文提出一种用户分类建模分析方法(分为快用户和慢用户)来估计分层蜂窝网络性能,它不同于以往的蜂窝层分类(分为微小区层和宏小区层)建模方法。此用户分类模型包括一个快用户模型和一个慢用户模型,两个模型都是简单的一维马尔可夫过程。理论分析和仿真结果都证明了用户分类分析模型的正确性。随后利用此模型分析了为速度阈值的作用和被阻用户重复呼叫情况下的网络性能。     

无线移动多媒体通信网的一种切换策略

该文提出了无线移动多媒体通信网中基于宽带呼叫业务和窄带呼叫业务的双向层间切换业务模型(BLHM)和单向层间切换业务模型(SLHM),分别研究了两种业务在模型中的新呼叫阻塞概率和切换呼叫失败概率,对由于层间切换机制带来的呼叫业务质量(QoS)下降的宽带切换呼叫进行了定量分析。另外,该文还提出了基于呼叫业务代价函数和呼叫业务QoS的信道分配算法。最后进行了计算机仿真,将两种模型的性能进行了比较。     

中继辅助蜂窝系统中降低盲区呼叫中断率的性能分析

该文介绍了一种盲区环境下在传统蜂窝系统加入中继功能的系统结构,并且描述了在这种环境下系统的解析模型。然后在这个模型的基础上,通过数学解析得到这种中继辅助蜂窝系统的呼叫中断概率。最后通过数值分析和性能比较证明了在盲区环境中,与无中继辅助的传统蜂窝系统相比较,中继辅助蜂窝系统可以获得更低的呼叫中断率。并且分析了节点移动速度、呼叫平均服务时间和节点覆盖半径等系统参数对这两种不同蜂窝系统性能的影响。     

两跳中继WCDMA蜂窝系统的性能分析

该文首先介绍了一种两跳中继WCDMA蜂窝系统结构,建立了系统的解析模型。然后在这个模型的基础上,分别得到了系统的平均下行传输速率和数据包呼叫请求阻塞概率。最后通过数值计算分析了各种系统参数对两跳中继WCDMA蜂窝系统性能的影响,并和传统非中继WCDMA蜂窝系统以及具有拥塞控制功能的两跳中继WCDMA蜂窝系统进行了比较。     

一种半速率蜂窝移动通信信道指配策略

本文提出了一种新的蜂窝移动通信系统信道指配策略——基于紧凑模式的半速率信道借用指配策略(SRCPCB).这种策略将半速率信道的思想引入到新近提出的CPCB策略中,以短时间降低部分呼叫的话音质量为代价,来降低系统的呼叫阻塞.通过各种业务模型的仿真,获得了系统的初始呼叫阻塞率、强制中断率和话音质量下降率等性能指标.结果表明:SRCPCB的系统综合性能优于FCA、DCA、BCO、BDCL、CPDCA和CPCB等策略.这对于缓解系统频谱资源紧缺、改善系统性能等具有十分重要的意义.     

卫星通信系统中的呼叫接入控制

分析比较了地面蜂窝移动通信系统和卫星通信系统在呼叫接入控制中的差异，并在此基础上重点分析讨论了卫星通信系统在呼叫接入控制中所必须考虑的策略。     

基于HBP编码结构的MVC快速算法

针对MVC系统中运算量最大的矢量预测部分——单向搜索和双向搜索,该文提出一种快速算法。根据多视点视频的序列相关性,采用立体-运动约束模型在运动域和视差域进行联合迭代单向搜索,设计可信度因子来自适应地调整修正搜索窗口,同步搜索得到运动和视差矢量。此外,通过分析双向预测宏块的特性,提出一种双向搜索提前中止算法。实验结果证明该文算法的有效性,能在保持编码质量的同时极大减少算法复杂度。     

宿舍通信广播双向呼叫系统(下)

<正> 双向呼叫显号通话系统 单向呼叫系统简单、可靠、实用,但只能由主机呼叫分机,分机不能呼叫主机,推广会有局限性。具有双向呼叫功能的分机可按单钮报送本机编号并呼叫主机,主机电话响铃,显号器显示分机编号,搞机可双工通话。广泛用作校舍、军营、监狱,旅馆、酒吧等场所的通话、报警、广播。     

基于多维马尔可夫链的两跳中继可变数据速率蜂窝系统建模

首先介绍了一种两跳中继可变数据速率蜂窝系统结构,并且利用多维马尔可夫链建立了系统的模型.然后在这个模型的基础上,分别得到了系统的平均下行吞吐量和呼叫请求阻塞概率.最后通过数值计算分析了各种系统参数对两跳中继可变数据速率蜂窝系统性能产生的影响.研究结果表明:与传统蜂窝系统相比,两跳中继蜂窝系统可以增加5～50%左右的平均下行吞吐量,同时可以有效降低系统的呼叫请求阻塞概率.     

双向寻呼

<正> 正当寻呼市场日渐趋冷之际,上海国脉通信股份公司于近期推出了双向寻呼业务,此举为寻呼业开辟了一个新的经营天地,也引起了业内人士的关注。 何谓双向寻呼 目前人们熟悉的寻呼方式是由寻呼台向所覆盖范围内所有用户同播公用信息、向被叫用户播发专有信息、寻呼机主单方接收寻呼信号的通信方式,这种方式也称之为单向寻呼。单向寻呼时,呼叫方事先无法确定被叫方的方位,被叫方只有通过电话复机才能同呼叫方取得联系。而双向寻呼时,被叫方在收到呼叫信息后,只需按一个设定的键,就会自动把自己的寻呼号码通知系统,双向寻呼系统以反呼的方式告诉呼叫方对方信息已收到(对方必须是同一个寻呼网络的用     

DYNAMIC GUARD CHANNEL ASSIGNMENT FOR BIDIRECTIONAL CALL-OVERFLOW SCHEME IN HIERARCHICAL CELLULAR SYSTEM

In this paper, a Hierarchical Cellular System (HCS) supporting two classes of users with high and low velocity is considered. Based on the analytical model of the bidirectional calloverflow scheme, a new dynamic guard channel assignment method is proposed. In this method,the number of guard channels in both macrocelis and microceiis varies in reMtime according to the different call traffic load in the HCS, and as a result, the lowest dissatisfaction grade of users is achieved.     

Recurrence times of buffer overflows in Jackson networks

The estimation of the statistics of buffer overflows in networks of queues by means of simulation is inherently costly, simply because of the rarity of these events. An alternative analytic approach is presented, with very low computational cost, for calculating the recurrence time of buffer overflows for Jackson networks in which the recurrence times of buffer overflows in a network are expressed in terms of the recurrence times for overflows of individual buffers, isolated from the network. This result is applied to the buffer allocation problem for queueing networks, providing extensions and further justification for a previously derived heuristic approach to this problem     

The effects of SiO2 barrier between active layer and substrate on the performance and reliability of polycrystalline silicon thin film transistors

We report on the performance and hot carrier stress (HCS) reliability of n-channel and p-channel poly-Si thin film transisters (TFT)s fabricated on SiO₂-coated 1737 glass or bare 1737 glass substrates. Low-pressure chemical vapor deposited (LPCVD) or atmospheric pressure chemical vapor deposited (APCVD) SiO₂ with different thicknesses are used as the impurity diffusion barrier layers. We have found that the performance and HCS reliability of n-TFTs on SiO₂-coated 1737 glass are superior to those of n-TFTs on bare 1737 glass. P-TFTs on SiO₂-coated 1737 glass, on the other hand, are observed to perform better than p-TFTs on bare 1737 glass substrates, however p-TFTs on SiO₂-coated 1737 glass are seen to undergo larger improvements in their OFF current, I_OFF, following the HCS compared to p-TFTs on bare 1737 glass. We also explore the impact of SiO₂ coating thickness on the performance and HCS reliability of the TFTs. The HCS reliability of the TFTs on SiO₂-coated 1737 glass substrates is observed to depend on the SiO₂ coating thickness. This was explained in terms of a phenomenological model which involves impurity and grain boundary traps. The presence of the former type of traps is controlled by the presence or absence of the SiO₂ coating, whereas the grain boundary traps are proposed to be sensitive to compressive and tensile stresses in the SiO₂ coating layer which are, in turn, dependent on the layer's thickness.     

Quasi-Resonant Zero-Current-Switching Bidirectional Converter for Battery Equalization Applications

A systematic approach to reform and analyze a soft-switching bidirectional dc-to-dc converter is proposed for cell voltage balancing control in a series connected battery string. quasi-resonant converter circuits have been designed to achieve the zero-current-switching (ZCS) to reduce the switching loss in bidirectional battery equalizers. The results indicate that the switching loss and energy transfer efficiency can be substantially improved using the quasi-resonant ZCS (QRZCS) technology in a battery charging system with an individual cell equalizer (ICE). The validity of the battery equalization is further verified using an experimental installation involving a battery string of three lithium–ion cells. The simulation and experimental results show that the proposed QRZCS battery equalization schemes can achieve bidirectional battery equalization performance and reduce the MOSFET transistor switch power losses by more than 96% and increase the efficiency by around 20%$sim$30% compared with the conventional battery equalizer during an identical equalization process.     

Improved Bidirectional-Mode Expansion Propagation Algorithm Based on Fourier Series

In this paper, an improved version of a 2-D bidirectional eigenmode expansion propagation algorithm based on Fourier series expansion for modeling optical field distribution in waveguide devices is presented. The algorithm is very simple, numerically robust, and inherently reciprocal. It does not require root searching in the complex plane. Proper truncation rules are used to ensure good convergence properties for TM-polarized waves. Perfectly matched layers as absorbing boundary conditions can be implemented in a very simple way using complex coordinate stretching. The approach represents a transition between purely modal and Fourier expansion methods for modeling guided-wave photonic structures.     

MOSFET drain engineering analysis for deep-submicrometerdimensions: a new structural approach

A new MOS transistor structural approach (hot-carrier-induced MOSFET) capable of substantially suppressing adverse hot-carrier effects, while maintaining the other desired performance and manufacturability characteristics of deep-submicrometer MOSFETs (L _gate⩽0.35 μm) is described. This structure is unique in having a lower doped N^- region located behind (or above) a very shallow, steeply profiled source/drain junction. In contrast, LDD types of MOSFETs have an N^- region with a more graded doping profile immediately adjacent to the channel region. The simulated characteristics of the HCS MOSFET structure indicate approximately one order of magnitude less substrate current in comparison to an LDD type of MOSFET whose structure and doping parameters are optimized for combined performance, reliability, and manufacturability. In terms of combined performance, reliability, and manufacturability, the HCS MOSFET should permit MOSFET devices to be more successfully scaled at deep-submicrometer dimensions     

EOC编解码分层实现方法

适应有线数字电视整体平移,同轴电缆网络必须进行双向改造,以杭州初灵信息技术有限公司的Cab．1ink系列的EOC产品为蓝本,分层介绍EOC的工作原理,为实现双向业务和增值服务提供最优的接入方案。     

Object recognition using multilayer Hopfield neural network

An object recognition approach based on concurrent coarse-and-fine matching using a multilayer Hopfield neural network is presented. The proposed network consists of several cascaded single-layer Hopfield networks, each encoding object features at a distinct resolution, with bidirectional interconnections linking adjacent layers. The interconnection weights between nodes associating adjacent layers are structured to favor node pairs for which model translation and rotation, when viewed at the two corresponding resolutions, are consistent. This interlayer feedback feature of the algorithm reinforces the usual intralayer matching process in the conventional single-layer Hopfield network in order to compute the most consistent model-object match across several resolution levels. The performance of the algorithm is demonstrated for test images containing single objects, and multiple occluded objects. These results are compared with recognition results obtained using a single-layer Hopfield network.