Priority Channel Assignment in Tandem DSI

DSI (digital speech interpolation) is a technique for increasing the utilization of telephone transmission facilities by allocating transmission channels during intervals of active speech (talkspurts) only. The use of DSI for tandem connections, where DSI links are connected in cascade via circuit switching, poses a problem, however, since the voice-quality degradation that is inevitable in each DSI link can be accumulated to an unacceptable level as the number of DSI links in an end-to-end call connection increases. To cope with this problem, we propose the use of a priority channel assignment technique. An example of such a technique is one that provides preference in channel assignment at each DSI process in a network to calls that have passed through at least one prior DSI link. We evaluate the performance of priority assignment schemes for TASI-type DSI analytically and show that the overall voice-quality degradation of a multi-DSI link call can be improved significantly through the use of priority assignment.     

提高PLC系统可靠性的措施

介绍了PLC系统可靠性设计方面的一些经验和方法,对硬件、软件抗干扰设计进行了分析并提出了可取的措施.     

动力环境集中监控系统可靠性的提高

为实现电源设备乃至通信机房的少人或无人值守和集中维护,必须建立一套完善的电信局动力环境集中监控系统。文中结合番禺区电信局的实际,讨论了提高系统运行可靠性的几点措施,包括硬件方面与软件方面的手段,关键在于加强系统的运行管理。     

基于动态优先级表的TDMA时隙分配

Ad Hoc网络组网效率提升的一个重要方面就是研究高效的时隙分配算法,动态TDMA时隙分配机制已经成为提高组网效率的一个热门研究点。这里基于动态优先级表提出一种新颖的动态时隙分配算法,该算法能在时间维上保证各节点对空闲时隙资源竞争使用的公平性。仿真结果表明基于动态优先级表的时隙分配算法能高效利用时隙资源,提高信道利用率。     

A Scheduling Algorithm with Dynamic Priority Assignment for WCDMA Systems

In third generation WCDMA systems, shared channels allow many users to jointly utilize a single Orthogonal Variable Spreading Factor (OVSF) code. In this paper, we propose a Scheduling Algorithm with Dynamic Priority Assignment (DPA) which is designed for the Downlink-Shared channel (DSCH) of 3G WCDMA systems and operates within a cross layer framework. The DPA scheduler has low computational complexity and is able to provide QoS differentiation among traffic flows based on their delay sensitivity. Through the cross layer framework, DPA takes into account the variations of the wireless channel, and exploits processing gain to improve transmission quality and enable service provisioning when possible. Additionally, by providing a guaranteed rate per traffic flow at each scheduling period, DPA can offer a deterministic delay bound to each connection when transmissions are reliable. Stochastic delay guarantees under transmission power limitations are also provided when the traffic flows are identical. Simulation results show that DPA outperforms Feasible Earliest Due Date (FEDD), a variation of EDD for wireless environments.     

具有优先级的指派问题数学模型及应用

在实际的指派问题中，常会遇到某个任务需要优先考虑的问题，本文建立了具有优先级的指派问题数学模型。在此数学模型中，优先级较高的任务得到了优先考虑。最后，用一个例子来阐明该问题的解法。     

一种基于容忍度的优先级动态轮询协议

根据利用卫星平台进行战场超视距情报数据转发的应用需求,针对卫星高速数据链的业务特点,提出了一种基于容忍度的优先级动态轮询协议;设计了帧结构和基于容忍度的优先级动态时隙分配算法及其流程;最后利用Opnet仿真软件仿真验证。仿真结果表明,改进后的协议通过容忍度函数实现了不同业务量、不同优先等级下时隙的动态调整,既可以使高优先级业务时延性能得到保障,又不会"饿死"低优先级请求,获得了较好的"公平性"。     

Providing Throughput Guarantees in 802.11e WLAN Through a Dynamic Priority Assignment Mechanism

Supporting real-time and interactive traffic in addition to traditional data traffic with a best-effort nature represents a constantly rising need in any kind of telecommunications environment. The IEEE 802.11 based WLAN (Wireless Local Area Network) environment does not represent an exception. This is why at different protocol layers, and primarily at the MAC layer, many efforts are being put by both the research community and the standardization bodies to design effective mechanisms for user QoS (Quality of Service) differentiation. Although early results are coming into sight, such as, for example, the IEEE 802.11e standard release, still a thorough research activity is required. Aim of the present paper is to contribute to the cited research issue by proposing an improvement to the “static” traffic prioritisation mechanism foreseen by the IEEE 802.11e MAC (Medium Access Control) protocol. This latter shows a twofold drawback. First, there is no certainty that QoS requirements relevant to a given application are always fulfilled by the “statically” associated priority. Second, resource requests of the applications are not adapted to the (usually highly) variable traffic conditions of a distributed WLAN environment. The algorithm we propose is specifically tailored to “dynamically” assign 802.11e MAC priorities, depending on both application QoS requirements and observed network congestion conditions. It is carefully designed, implemented into a system simulation tool, and its highly effective behaviour assessed under variable traffic and system conditions. Antonio Iera graduated in Computer Engineering at the University of Calabria, Italy, in 1991 and received a Master Diploma in Information Technology from CEFRIEL/Politecnico di Milano, Italy, in 1992 and a Ph.D. degree from the University of Calabria, Italy, in 1996. From 1994 to 1995 he has been at the Mobile Network Division Research Center, Siemens AG Muenchen, Germany to participate to the CEC Project “RACE II 2084 ATDMA (Advanced TDMA Mobile Access)” under a “Commission of European Communities Fellowship Contract in RACE Mobility Action”. He has been with the University of Reggio Calabria, Italy, from 1997 to 2000 as Assistant Professor, and from 2001 to 2005 as Associate Professor. Currently, he is Full Professor of Telecommunications at the same University. In 1995 and in 1996 he has been the recipient of an IEEE Paper Award for the papers presented at the IEEE International Conference on Universal Personal Communications ICUPC'95, and an IEICE/IEEE Outstanding Paper Award for the paper presented at the IEEE ATM Workshop'99, respectively. He served as member of Technical Program Committees of several International Conferences, and in 2003 he has been co-Guest Editor for the special issue “QoS in Next-generation Wireless Multimedia Communications Systems” in the IEEE Wireless Communications Magazine. His research interests include QoS control and resource management in Personal Communications Systems and Enhanced Wireless and Satellite Systems. Giuseppe Ruggeri received the degree in electronics engineering from the University of Catania, Italy, in 1998. He received the Ph.D. degree in electronics, computer science and telecommunications engineering with a dissertation on “Advanced Methods to Improve the QoS in VoIP Systems Based on VBR Speech Coders”. His interests include the field of adaptive-rate voice transmission for IP Telephony applications, and support of Quality of Service in heterogeneous wireless networks and WLAN-3G interconnection-integration . He is currently Assistant Professor in the Department of Computer Science, Mathematics, Electronic and transportation systems (DIMET) at the University “Mediterranea” of Reggio Calabria. His mail address is ruggeri@ing.unirc.it. Domenico Tripodi received M.S. degree (cum laude) in electronic engeneering from the University ‘Mediterranea' of Reggio Calabria, Italy in 2003. He won a post-degree scholarship from CNIT in 2004, and he is currently at CNIT Research Unit of Reggio Calabria. His reasearch interest are in the area of QoS provisioning in Mobile Ad-Hoc Networks.     

输电线路在线监测系统可靠性提升方法研究

根据输电线路在线监测系统的特点和实际运行情况,对其常见故障进行了分类与分析,并建立了可靠性模型。在此基础上,提出了针对电路设计、机械设计、电源设计、标准化设计、实验验证等各个环节的可靠性提升方法。最后提出了针对输电线路在线监测系统的可靠性预计方法,并对所优化的系统进行了可靠性预计,得到了系统平均无故障工作时间（MTBF）的预计值,在一定程度上验证了可靠性提升方法的应用效果。     

红外探测器组件可靠性指标分配初探

试图从分析工外探测器组件的组成及其可靠性因素入手，以６０元ＰＣ－ＭＣＴ探测器组件为例，介绍了 几种可靠性指标分配方法和相应的结果，并分别做出评估。     

提高单片机测控系统可靠性的若干措施

在分析提高单片机测控系统可靠性的重要性以及系统干扰主要来源的基础上,从硬件和软件两个方面对提高单片机测控系统的可靠性提出了一些简单、有效、实用和易于实现的一般方法,并重点讨论了程序运行出轨的问题和自动恢复的方法。     

提高高炉控制系统可靠性的探索及应用

高可靠性是过程控制系统的第一要求,为了达到系统的高可靠性,我们通常会在控制系统的设计和应用中采用冗余、屏蔽及接地等技术.本文阐述了高可靠性技术在莱钢高炉控制系统中的成功应用.     

提高电路中元器件的使用可靠性

元器件的使用可靠性是整机可靠性的关键和基础。结合工作实践,对电路设计中元器件的使用性、失效原因进行了分析、总结,并提出了提高电子元器件使用可靠性的建议。     

提高MOS功率晶体管封装可靠性技术研究

功率MOS晶体管的正向导通电阻是器件的重要指标,严重影响器件的使用可靠性。从封装材料、封装工艺等方面论述功率MOS管降低导通电阻、控制空洞、提高器件可靠性的封装技术,并通过一些实例来阐述工艺控制的效果。     

提高电子产品制造硬连接可靠性实践

随着模块化设计的快速推进,越来越多的电子产品采用了模块直接插入母板的结构形式,而在实际工程应用中,时常会出现模块插入困难的装配问题.针对这种现象的发生进行了分析,提出了设计上的建议,在工艺上设计出了相应的工装.实践验证,从根本上解决了装配中模块插入母板的困难局面.     

提高微波功率晶体管在使用中的可靠性

微波功率晶体管是固态发射机及T/R组件的核心器件,其可靠性对系统的可靠性指标起着决定性的作用。统计数据表明,使用不当造成晶体管的失效占到很大的比例。通过对瞬态过载、结温、参数漂移等影响微波功率晶体管使用可靠性的因素进行分析,提出了用保护电路、降额设计、容差设计等手段来提高微波功率晶体管的使用可靠性,对工程设计有一定的指导作用。     

ATM优先级队列的质量控制

在ＡＴＭ队列中可以采用恰当的优先级方案对具有不同ＱＯＳ指标的业务进行适当的控制。本文提出了一种综合的ＡＴＭ队列管理方案，建立了相应的系统模型，并给出了理论分析和模拟结果，表明这种方案对ＡＴＭ业务的质量控制是有效的。     

Technological Methods for Improving IC Reliability in Mass Production

Technological methods for improving the reliability of silicon ICs in mass production are discussed. They include low-temperature processing, the compensating technology, and the equalizing technology.     

嵌入式系统优先级反转问题的分析

本文介绍了嵌入式系统任务调度优先级反转的一个实例.通过实例的讨论对嵌入式系统优先级反转有一个更深入的了解,有助于在编程中避免此类问题的发生.     

Coordinated Resource Assignment in a Fixed Wireless System

In this paper, we study the interferencemanagement and resource allocation problem in apacket-switched, fixed, broadband, Time DivisionMultiple Access (TDMA) wireless system. These systemshave the potential to provide high-speed data access to the homeand therefore are of current interest. The systemcapacity is limited by the co-channel interference,which arises from both intercell and intracelltransmissions. The intracell interference management andresource allocation, which significantly impacts thesystem performance, is the focus of this study. The goalis to design efficient resource allocation schemes to combat intracell interference so as toimprove the system capacity and service quality. Weaddress the following issues: (1) estimating the optimalcapacity of the system; (2) proposing resourceallocation schemes with reasonable complexity that areclose to optimal; and (3) proposing a new class of powercontrol schemes that are suited to intracellinterference management. Two resource allocation schemes are proposed: Max-Min Scheduling Protocol(MMSP) and Revisited Max-Min Scheduling Protocol(RMMSP). We show via simulations that these schemescombined with the new power control provide close tooptimal performance.