QoS provisioning for multiple non‐real‐time services in cellular wireless networks

Future mobile services are expected to include various non‐voice oriented services. One important category of non‐voice oriented mobile services is non‐real‐time services. When a mobile user establishes a connection to access non‐real‐time service, the mobile user usually cares about whether the total time to complete its data transfer is within its time tolerance. In addition, different mobile users may have different bandwidth requirements and different tolerances in the total completion time. It is essential for wireless systems to provide various mobile users with different total completion times. In this paper, two quality‐of‐service (QoS) metrics, called stretch ratio and eligibility percentage, are employed at a connection level to present the degree of the length of the total completion time. We devise a measurement based call admission control scheme that provides multiple QoSs for various mobile users which have different requirements of stretch ratios, eligibility percentages, and bandwidths. Extensive simulation results show that the measurement based call admission control scheme not only provides various satisfactory QoSs for mobile users but also produces high throughput. Copyright © 2010 John Wiley & Sons, Ltd.     

Advantage of InGaN-based light-emitting diodes with trapezoidal electron blocking layer

In this study, a trapezoidal-shaped electron blocking layer is proposed to improve efficiency droop of InGaN/GaN multiple quantum well light-emitting diodes. The energy band diagram, carrier distribution profile, electrostatic field, and electron current leakage are systematically investigated between two light-emitting diodes with different electron blocking layer structures. The simulation results show that, when traditional AlGaN electron blocking layer is replaced by trapezoidal-shaped electron blocking layer, the electron current leakage is dramatically reduced and the hole injection efficiency in markedly enhanced due to the better polarization match, the quantum-confined Stark effect is mitigated and the radiative recombination rate is increased in the active region subsequently, which are responsible for the alleviation of efficiency droop. The optical performance of light-emitting diodes with trapezoidal-shaped electron blocking layer is significantly improved when compared with its counterpart with traditional AlGaN electron blocking layer.     

Fluoride‐Catalyzed Deblocking: A Route to Polymeric Urethanes

We report a fluoride‐catalyzed deblocking of urethanes as “blocked” isocyanates. Organic and inorganic sources of fluoride ion proved effective for deblocking urethanes and for converting polyurethanes to small molecules. Distinct from conventional deblocking chemistry involving organometallic compounds and high temperatures, the method we describe is metal‐free and operates at or slightly above room temperature. The use of fluorescent blocking agents enabled visual and spectroscopic monitoring of blocking/deblocking reactions, and the selected conditions proved applicable to urethanes containing a variety of blocking groups. The method additionally enabled a one pot deblocking and polymerization with α,ω‐diols. Overall, this deblocking/polymerization strategy offers a convenient and efficient solution to problems that have limited the breadth of applications of polyurethane chemistry.     

基于新型脑皮层的VoLTE视频感知指标监控方法

针对VoLTE视频通话中存在延迟、卡顿等问题,本文提出一种新型闹脑层算法的VoLTE视频通话质量的评估方法。首先,运用脑皮层算法的HTM算法对VoLTE时间序的指标进行检测,然后利用同比环比加权及HTM循环预测加权进行VoLTE感知指标异常值替换,构造能够实时发现指标异常状况的指标监控模型。其次使用时间序列连续性检测及补全功能、同比环比加权平均值再加权的方法提高异常数据训练的准确性。然后通过对比验证VoLTE失败码的预测结果,验证该模型的监控结果的有效性。     

基于dSPACE的阻塞式交交变频系统实现

文中针对变频技术存在的缺陷,提出了一种基于dSPACE的脉冲阻塞式交交变频新思路。系统利用RTW对搭建的阻塞式交交变频系统数学模型进行代码生成,用于实现基于dSPACE的斩波调压控制策略。通过ControlDesk软件平台对实验中的参数和变量进行访问更改,实现了变频调压的目的,并在MATLAB 2011a环境下对变频系统进行了仿真。仿真与实验结果和理论相一致,验证了该系统控制策略的正确性及可行性,同时也为工业现场变频调速系统的设计与应用提供了依据。     

A novel mathematical teletraffic method to evaluate the interoperation of different standards with NOMA systems using order statistics

Basically, nonorthogonal multiple access (NOMA) allows controllable interferences by nonorthogonal resource allocation with a tolerable increase in receiver complexity, using successive interference cancellation (SIC). In this paper, authors show a novel mathematical model of teletraffic for users accessing, simultaneously, to Wi‐Fi and LTE services by using NOMA, calculating the birth–death process by order statistics. This methodology has not been previously used. The mathematical model is represented by a two‐dimensional Markovian process where the users can born or die in one system or another, independently, and results are validated through simulations. The outcomes demonstrate an increment of the sum‐rate gain for a system where users are ordered in the power domain using order statistics, according to the signal interference plus noise ratio (SINR), compared to a system where these statistics are not employed. By using the proposed mathematical model, the sum‐rate gain increases around 15%, and it is also demonstrated that this algorithm foresees a steady behavior of the sum rate, even when the number of channels is augmented, contrary when no order statistics are employed, in which the sum rate decreases considerably. On the other hand, the blocking probability is also demonstrated based on the chance of moving from one technology to another.     

基于BMP及CMR的抗主瓣干扰算法研究

瓣干扰算法。通过分析阻塞矩阵预处理后数据特征值的变化情况,修正预处理导致的过处理现象,从而重构协方差矩阵,该算法适用于阻塞矩阵预处理导致的自由度损失的情况,能够解决由于预处理导致的主瓣波峰偏移等失真问题,同时算法复杂度较低。该算法最大的优点是当采样快拍包含目标信号时,其抗干扰性能较好,快拍敏感度相比常规的波束保形方法更低,经实测数据验证,结果显示出该算法的优越性。     

浅谈1200芯骨架式光纤带光缆的研制及应用

随着我国光通信行业的发展,光纤光缆的制造技术业也得到了长足的发展,尤其是光纤带光缆,凭借其光纤密集度高外径小而广泛应用。本文重点介绍了1200芯骨架式光纤带光缆的结构设计原理、原材料的使用、关键制造工艺要点及应用,并给出了其性能测试结果,给超大芯数高密度光缆研发提供了积极意义。     

蓝牙耳机的主观评测方法

蓝牙无线耳机的使用主要分为音乐和通话两种场景。本文提出了一种主观评测音乐播放效果的方法,结果表明耳机的音乐播放效果都是很不错的。在通话测试部分,按照3GPP和沃达丰的测试规范进行上下行响度的测试,并对噪声消除进行了主观评测,结果表明,语音通话部分还有很大的改进空间。     

弹性光网络双重故障下的自适应保护级别算法

为了降低弹性光网络中双链路故障保护下的业务及带宽阻塞率、均衡带宽资源分配,提出了一种双重故障下的自适应保护级别算法。该算法综合考虑传输距离、调制格式等因素,根据链路频谱资源使用状态动态地更新链路惩罚系数,选取最佳路径进行传输,同时根据请求类型及网络空闲资源状态自适应地选择保护方法,为业务提供最大限度的保护。仿真结果表明,在双链路故障下,算法在阻塞率方面取得了较好的性能,同时均衡了网络中各链路上的资源使用。