WCDMA系统接口信令消息的描述与实现

WCDMA作为第三代移动通信系统的主流标准，能够提供多种类型的多媒体服务。为了实现各种用户平面数据的传输，系统会提前通过控制平面对所需的无线资源进行分配。由于配置过程是通过接口之间发送控制平面应用协议消息来实现的，因此能否正确有效地对信令消息进行编解码成为保证系统稳定工作的关键因素。3GPP标准中，ASN．1语言被用来描述接口信令消息。首先简要介绍了WCDMA系统结构以及主要接口协议，重点描述了ASN．1存在的意义及其编解码规则，最后给出了基于ASN．1的开发环境下应用层网络协议的开发流程。     

Event-driven,pattern-based methodology for cost-effective development of standardized personal health devices

Experiences applying standards in personal health devices (PHDs) show an inherent trade-off between interoperability and costs (in terms of processing load and development time). Therefore, reducing hardware and software costs as well as time-to-market is crucial for standards adoption. The ISO/IEEE11073 PHD family of standards (also referred to as X73PHD) provides interoperable communication between PHDs and aggregators. Nevertheless, the responsibility of achieving inexpensive implementations of X73PHD in limited resource microcontrollers falls directly on the developer. Hence, the authors previously presented a methodology based on patterns to implement X73-compliant PHDs into devices with low-voltage low-power constraints. That version was based on multitasking, which required additional features and resources. This paper therefore presents an event-driven evolution of the patterns-based methodology for cost-effective development of standardized PHDs. The results of comparing between the two versions showed that the mean values of decrease in memory consumption and cycles of latency are 11.59% and 45.95%, respectively. In addition, several enhancements in terms of cost-effectiveness and development time can be derived from the new version of the methodology. Therefore, the new approach could help in producing cost-effective X73-compliant PHDs, which in turn could foster the adoption of standards.     

优化TLV编码规则

抽象语法标记ASN．1是一种ISO／ITU-T标准,描述了一种对数据进行表示、编码、传输和解码的数据格式。ISO协议体系中的应用层协议使用了ASN．1来描述它们所传输的协议数据单元。ASN．1取得成功的一个主要原因是它与几个标准化编码规则（如基本编码规则BER）相关。TLV编码是指先对Tag编码,再对Length编码,最后对Value编码。BER编码确定的编码方式就是这样的。在实际的通信中,通常特定类型编码中数据的长度是已知的,在数据字典中有明确的标识。提出了一种优化TLV编码的方法,使用一个比特的标志位,将长度字段作为编码中一个可选择的项目,而不是必须存在的项目,以此来缩短TLV编码的长度。在满足需求的前提下,优化后的TLV编码可以大幅度地提高数据传输效率。     

An improved error handling method in SNMPv2 protocol operations

SNMPv1 is very successful due to its simplicity,flexibility,and extensibility,However,simplicity can also be a drawback,In SNMPv1,a manager can only reteieve one piece of information at a time,and an agent merely reports one protocol operation.These two interactions enlarge the number of protocol exchanges between a manager and an agent.SNMPv2 permits the retrieval of large data blocks,but the errors can only be handled one by one.These errors continually occur in a multivendor network.This paper proposes an error handling method in SNMPv2 protocol operations.In this method,all errors within a received PDU(Protocol Data Unit) can be detected by the agent simultaneously.     

无线高速寻呼联网系统的IPNP网关的设计及实现

IPNP协议是FLEX全国高速寻呼联网系统的体系结构中十分重要的接口协议，是高速寻呼系统人工辅助席与自动寻呼系统的联网协议接口、主要就IPNP协议网关的设计进行了探讨，并对模块开发中几个关键的问题提出了较为合理的解决方案。     

网际管理信息库中模板转换技术的实现

TMN与SNMP网管系统的互操作技术,成为计算机网络与电信网络有效互连的关键技术之一。而网络管理信息库(MIB)包含了管理信息的定义,是网络管理的核心部件。文章分析了委托代理的工作原理,在IIMC研究的基础上,提出了SNMP-TMNMIB的转换机理及其转换的JAVA方法实现,为MIB的开发奠定了基础。该方法替代了手工转换,提高了效率并减少了因繁杂手工工作带来的错误。其显著优点是集中采用一个委托代理实现管理者与整个子网或多个网络设备间的CMIP与SNMP的协议转换,它比在每个被管网络设备内嵌入CMIP代理经济、方便和有效。所采用的映射技术使Proxy具有扩展性,是一种具有实用价值的异网管理技术。     

3G移动通信系统安全协议的描述及实现

在对3G通信系统安全相关算法和协议研究的过程中,采用ASN.1来描述相关的协议,通过VC++来实现相关的安全算法和ASN.1的编解码器。相关信令消息的传输码基于串行线仿真和传输。文中所提到的协议描述及实现方法,可广泛应用于通信协议的研究及测试。     

SNMP与拒绝服务攻击

众所周知，SNMP(简单网络管理协议)已广泛用于网络设备的监督和管理。但是最近的研究表明，许多实现此协议的网络设备都可能不同程度的受到拒绝服务的攻击，本文分析了其中存在的一些弱点，并提出了预防的手段。     

Distribution of Quasimidranges and Associated Mixtures

In this paper are presented and discussed tabulations of the cumulative distribution functions of quasimidranges and mixtures of quasimidranges of samples from a normal distribution. The tabulations extend up to samples of size 21. For quasimidranges not involving the extreme values of the sample, the departure from normality is very small. The physical problem giving rise to the mixtures is discussed.     

The Inverse of a Centrosymmetric Matrix

In this paper we have obtained, following Craig's procedure, a simplified form for the ASN of a single sampling plan under curtailment arising from observation of enough nondefectives to accept a lot or enough defectives to reject a lot.