标准摘要
[中文适用范围]： 本国际标准规定了使用 CALM 架构和协议，通过公共无线网络（包括蜂窝电话和移动无线宽带 (MWB) 系统）提供智能交通系统 (ITS) 服务的一般要求。特别是，本国际标准规定了公共无线网络应包含的协议和参数，以支持在 ITS 环境中需要异构切换或媒体无关切换 (MIH) 以维持链路，或根据媒体选择策略确定为可取的长期通信链路，且该切换由公共无线网络提供。本国际标准并非主要关注在没有异构小区/小区切换（即所谓的游牧服务）的情况下通过公共无线网络使用 CALM 的要求，但在单个小区范围内启用此类系统使用的一般要求也提供了。 wherever practicable, 本国际标准是通过参考适用的现有标准并选择采用而开发的。提供了所需的区域变体。具体而言，对于本国际标准，公共无线网络的现有国家和国际标准是通过引用采用的，并未在此重新定义。应用特定的上层不包含在本国际标准中，但将由应用标准（可能不是特定于技术的）驱动。 [外文原描述]： ISO 25111:2009 specifies general requirements for the provision of ITS services, using the CALM architecture and protocols, via the use of public wireless networks [including cellular telephony and mobile wireless broadband (MWB) systems]. In particular, ISO 25111:2009 specifies protocols and parameters that public wireless networks shall include to support prolonged communication links in ITS environments where heterogeneous handovers or media independent handovers (MIH) are either necessary to maintain the link, or desirable as determined by media selection policies, and such handover is provided by the public wireless network. The requirements for the use of CALM via public wireless networks where there is no provision for heterogeneous cell/cell handover (i.e. so-called nomadic services) is not the central focus of ISO 25111:2009, but general requirements to enable the use of such systems, within the limits of the range of a single cell, are also provided. Wherever practicable, ISO 25111:2009 has been developed by reference to suitable extant standards, adopted by selection. Required regional variations are provided. Specifically, for ISO 25111:2009, extant national and International Standards for public wireless networks are adopted by reference and are not redefined herein. Application-specific upper layers are not included in ISO 25111:2009, but will be driven by application standards (which might not be technology specific).
英文名称Intelligent transport systems — Communications access for land mobiles (CALM) — General requirements for using public networks