CN100350405C - 经由异步传输模式网络维持数据流的系统和方法 - Google Patents
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Abstract
提供一种异步传输模式(ATM)数字文档传送系统。用户侧单元(2)配置来容许用户定购和接收数据流。缓冲器(34)耦合到用户侧单元(2),以便在将数据流发送到用户之前存储数据流。服务器(22)包括存储其上的通过交换ATM网络(100)传送给用户的数字文档。耦合到服务器(22)和用户侧单元(2)的网络控制系统(11)用来控制在服务器(22)和缓冲器(34)之间的数据流的数据速率,以确保在服务器(22)和用户侧单元(2)之间的物理层的丢失期间维持从用户侧单元(2)到用户的稳定数据流。
Description
技术领域
本发明一般涉及网络通信,尤其涉及一种在丢失物理层协议后用于恢复数据流的异步传输模式(ATM)流数据传送系统和方法。
背景技术
视频点播(VoD)、音频点播和其他流数据的传输应用是用于家庭娱乐服务业的新兴技术。例如,VoD服务容许用户实时地从位于远端设备的服务器上存储的大量视频内容收集中请求视频服务。例如,能够通过诸如电话系统或电缆网络的网络系统提供视频传输。然而,必须有足够数量的带宽来保持从存储系统到用户设备的数据连续传输。在视频服务器和用户的设备之间的带宽总量最终决定服务器在任何给定时间能够支持的最大数量的同步视频流。
一种关键的通信传输技术是非对称数字用户线(ADSL),即一种调制解调器技术,该通信传输技术使现有的公共信息网变换为能够适应更宽带宽的需要。ADSL将现有的双绞线电话线转换为用于多媒体和高速数据通信的接入路径。不用安装新的电缆,ADSL的速率可以说按50倍或更多倍扩展了现有的接入容量。
非对称数字用户线ADSL技术包括通过双绞铜线连接的调制解调器,在该双绞铜线中能够实现更高的传输速率。当在这些双绞线上传送数据时,由于改变了线的状况,所以DSL调制解调器物理层将可能丢失同步。这些线的状况能够取决于脉冲噪声以及其他相邻的干扰源。该同步丢失也能够在用户正观看节目(例如,诸如视频点播(VoD)的按观看付费的服务)的时间期间产生。如果所述调制解调器丢失了同步并企图再同步,则用户丢失一部分流数据,并且干扰或甚至中断视频或音频等。如果所述DSL调制解调器丢失物理层同步,则视频或数据流不能够再通过网络从视频服务器向用户发送,并且导致服务中断。
所以,需要一种当DSL调制解调器丢失物理层同步时阻止数据流中断的系统和方法。
发明内容
根据本发明,提供一种异步传输模式(ATM)数字文档传送系统。用户侧(premise)单元,其配置来容许用户定购和接收数据流;缓冲器,其耦合到用户侧单元,以便在向用户发送数据流之前存储数据流;服务器,其包括存储其上的通过交换ATM网络传送给用户的数字文档;耦合到服务器和用户侧单元的网络控制系统,用于控制在服务器和缓冲器之间的数据流的数据速率,以确保在服务器和用户侧单元之间的物理层的丢失期间维持从用户侧单元到用户的稳定数据流。
一种用于在异步传输模式(ATM)网络上维持数据流的方法,该方法包括:提供配置来容许用户接收数据流的用户侧单元;以及在向用户发送数据流之前在缓冲器中存储一部分数据流;通过交换异步传输模式网络从服务器发送数据流;控制在服务器和缓冲器之间数据流的数据速率,以确保在服务器和用户侧单元之间的物理层的丢失期间维持从用户侧单元到用户的稳定数据流,其中控制数据流的数据速率的步骤包括维持步骤(208),在缓冲器(34)中维持来自数据流的数据量,以便在丢失物理层后的一段时间保持到达用户的数据流。
附图说明
现在结合附图来详细描述图解说明的实施例,本发明的优点、特性、以及各种附加特征将更为明显。其中:
图1示出根据本发明的如果物理层丢失发生时向用户提供数据流的服务器系统的示例性数字用户线(DSL)系统结构;和
图2是根据本发明的如果物理层丢失发生时向用户提供数据流的说明性处理流程的框图。
应该理解附图的目的是为了说明本发明的原理,而不是用于说明本发明唯一可能的配置。
具体实施方式
本发明提供一种恢复机制,以便在物理层丢失发生时维持在数字用户网络上的数据流。恢复机制确保足够数量的数据缓存在用户的位置,以便在系统中提供足够的延迟来解决恢复物理层的故障时间。在诸如数字用户线(DSL)的调制解调器技术中,经常需要DSL调制解调器的再同步。在再同步过程期间,中断传送的数据流,从而在用户处导致暂停或其他中断。好处在于,当发生DSL调制解调器物理层同步丢失时,该恢复机制对应用流服务(例如,视频和音频)的用户是透明的,例如,当DSL调制解调器处于再同步的过程中时,中断对用户是透明的。根据本发明,如果调制解调器丢失同步,并且尝试再同步,然后即刻成功地完成再同步,则用户能够经历服务中断。用户在观看和收听期间将不会注意到任何服务质量下降。
将会理解本发明是根据视频点播(VoD)系统而描述的。然而,本发明有更广的范围,并可以包括能够在交换网络上传送的任何数字多媒体文档,例如,音频文档。此外,本发明可应用到使用任何定购(ordering)方法的系统,该定购方法包括由电话、置顶盒、计算机、以及卫星链路等进行的定购。本发明通过DSL网络来进行描述。然而,本发明的原理可以扩展到利用ATM技术的电缆、无线电或其他网络类型。
也应该理解在附图中显示的单元可以以硬件、软件或它们的结合的各种形式来实现。最好,这些单元以在一个或多个合适当地程序化的通用设备上的硬件实现,其可包括处理器、存储器和输入/输出接口。
现在详细参考附图,其中在所有几张附图中同样的附图标记表示类似或相同的组件,并且首先参考图1,用于集成视频、数据和音频服务的DSL系统结构1在利用本发明的示例性DSL环境中示出。系统域1由几个功能块组成。系统域由中心局(CO)设备100和用户侧设备(CPE)2组成。在系统域中的组件块和它们各自的接口是:用户侧设备(CPE)2、数字用户线接入多路复用器(DSLAM)9、ATM交换机10、因特网协议(IP)路由器13、以及ATM终端负载12。示出ATM交换机10耦合到连到卫星17、无线广播18或电缆19网络的节目指南服务器/视频服务器22。ATM交换机10也耦合到DSL终端负载(terminator)12和IP路由器13对以从因特网14接收因特网协议IP分组数据。
当前的用户侧设备(CPE)2包括DSL调制解调器单元30,该DSL调制解调器单元30通过简易老式电话业务(POTS)与分开的模拟电话3-5接口、与连接到PC桌面系统7的10Base-T以太网接口、与连接到置顶盒8的以太网或RS-422接口,其中置顶盒8具有解调器并连接到电视或视频显示器8′。从用户的模拟端,CPE设备2接收从每个模拟电话3-5输入的模拟信号、将模拟输入信号转换为数字信号、以及将该数据分组为ATM分组(通过ATM的POTS),就每个连接而言具有唯一虚拟信道识别符/虚拟路径识别符(VPI/VCI)。本领域的技术人员已知ATM是面向连接的协议,并且同样在每个信元(cell)的首标中存在连接识别符,该识别符明确地将信元与给定的在物理链路上的虚拟信道相关联。该连接识别符包括两个子字段,即,虚拟信道识别符(VCI)和虚拟路径识别符(VPI)。将这些识别符一起用在多路复用信元、多路分解信元和通过网络交换信元中。VCI和VPI不是地址,但当连接建立时被明确地分配到ATM节点连接之间的每段链路上,并且对于连接期间保持虚拟信道识别符(VCI)和虚拟路径识别符(VPI)。当使用VCI/VPI时,ATM层能够根据多个连接异步地交织(多路复用)信元。
以太网数据也被封入具有唯一的VCI/VPI的ATM信元。将ATM信元流发送到CPE单元2的DSL调制解调器,以便进行调制并传送到DSLAM单元9。另一方面,DSL信号由在用户侧设备2中的DSL调制解调器30接收和解调,并传送到VCI/VPI检测处理。然后提取具有与终端用户电话的VCI/VPI匹配的VCI/VPI的ATM信元数据并将其转换为模拟POTS,以便传送给电话。提取具有与终端用户以太网的VCI/VPI匹配的VCI/VPI的ATM信元数据,并将其传送到用于向端口传送的以太网收发器。
数字用户线接入多路复用器(DSLAM)9对来自多个DSL调制解调器的数据进行解调并在与其余网络连接的ATM骨干网上汇集该数据。DSLAM 9通过在ATM输出上汇集的DSL线来向ATM交换机10提供用于分组、信元和/或基于电路的应用的迂回信程(back-haul)服务。
ATM交换机10是ATM网络的骨干。ATM交换机10在网络中执行各种功能,包括信元传输、多路复用和汇集、通信量控制、以及ATM层管理。对于系统域1中的特别益处,ATM交换机提供与DSLAM 9和因特网网关(因特网协议IP路由器13和DSL或ATM终端负载12)有关的信元路由和缓存,以及提供与多个电话链接交换机15有关的T1电路仿真支持。ATM交换机10可以耦合到与卫星、无线广播或电缆网连接和接口的节目指南服务器/视频服务器22。ATM交换机10也耦合到ATM终端负载12和IP路由器13对上以便从因特网14接收因特网协议IP分组数据。
NCS 11为终端点提供信令,该信令根据用户的访问权和请求控制设置和取消虚拟电路。此外,NCS 11也提供容许用户控制内容流的功能,例如,诸如可以由用户以和传统的VCR几乎相同的功能控制内容的暂停、停止、播放、前进、以及反转等的功能。NCS 11也提供有关用户记帐目的的活动信息。
NCS 11提供地址转换、需求分配和呼叫管理功能,并且NCS 11管理包括电话呼叫以及服务请求和定购的起点和终点的DSL/ATM网络。NCS 11基本上是在第5类(class 5)PSTN交换机15(例如,使用GR-303协议)和CPE 2之间的通信和转换控制信息的控制实体。网络控制系统11也可提供对于诸如向CPE下载代码的其他功能、带宽和呼叫管理功能、以及其他服务提供和设置任务。
NCS 11可以设置来发送例如从视频服务器22到用户的视频。视频数据流从位于服务提供商的网络中的视频服务器22发送给由NCS 11设立的ATM虚拟电路上的CPE 2。所述视频数据流离开视频服务器22并进入ATM首端网络1、进入DSLAM 9、然后在CPE 2处被接收。CPE 2能够向置顶盒8发送视频,该置顶盒包括视频解码器。在CPE 2和置顶盒8之间的接口可以包括例如1394电缆、以太网链路、以及同轴电缆等。用户正观看流内容的时候是系统的稳定状态条件。
CPE 2包括DSL调制解调器30。如果DSL调制解调器30丢失物理层同步,则能够不再通过网络从视频服务器22向用户侧设备2发送视频流,并且产生服务中断。本发明包括当DSL调制解调器丢失物理层同步时提供继续服务的系统和方法,并且将不产生观看内容的中断。
NCS 11包括管理程序33,与包括在CPE 2和DSLAM 9中的信令机制装置35一起使用该管理程序。在用户侧附加的硬件组件包括CPE 2中的缓冲器34,该缓冲器能够缓冲数据流以提供时间来再同步调制解调器或将协议的物理层带回到在线状态。在一实施例中,缓冲器34包括易失性存储器,其适合于容许大约20到30秒流内容的存储。这是基于数据传输率的。最初,当请求点播流内容时,在视频信号发送到用于解码的置顶盒解码器8和显示器之前最好填满缓冲器34。
信令机制装置35可以在NCS 11和DSLAM 9或CPE 2之间作为虚拟电路或硬布线电路来实现。一旦在DSLAM 9处检测到物理层信号丢失,DSLAM 9将立即向NCS 11转发消息。NCS 11检查以了解用户目前是否正接收点播流内容。当用户正接收点播流内容时,DSLAM 9尝试再同步DSL调制解调物理层。如果用户正接收点播流内容时,则NCS 11准备通知视频服务器什么时候已经发生再同步。
一旦在CEP 2处检测到物理层信号丢失,该CEP 2可以通知置顶盒8降低解码器的速度并以较低的速率(为了容许必要的延迟,例如,为了容许缓冲器34以较慢的速率腾空)对视频进行解码,或CEP 2继续以正常的速率或如果必要以较慢的速率来腾空连到置顶盒8的缓冲器34。
一旦再在DSLAM 9和CPE 2处发生再同步,CPE 2向NCS 11发送指示在缓冲器34中存储的最后单元的消息。NCS 11将最后单元的消息通知视频服务器22,然后视频服务器22增加将流内容发送到CPE 2上的缓冲器34的速率。该流内容将在一时间周期内以较高速率从视频服务器22发送到CPE2上的缓冲器34。对于较高速率的时间周期主要取决于在视频服务器22和CPE 2之间可用的带宽。尽管CPE 2以较高的速率接收流内容,CPE 2将不以该较高的速率向置顶盒解码器8发送内容。CPE 2仍然以该正常的特定速率向置顶盒8发送内容。所以,一旦在CPE 2处填满缓冲器34,CPE 2向NCS11发送指示缓冲器34填满的消息,并且视频服务器22需要返回来以正常速率发送流内容。NCS 11向视频服务器22通知缓冲器34填满,然后视频服务器22将恢复以合适的速率发送流内容。
在CPE 2和NCS 11之间的信令最好在共用的或专用的ATM虚拟电路上传送。在一实施例中,在CPE 2和NCS 11之间的信号在专用的虚拟电路上传送。每个用户CPE 2具有在NCS11和CPE 2之间专用的虚拟电路。在NCS11和视频服务器22之间的信令最好在共用的或专用的虚拟电路上传送。
参考图2并继续参考图1,示出根据本发明的在物理层丢失的情况下维持数据流的流程图。将根据诸如视频点播(VoD)系统的点播文档请求系统来图解说明地描述图2。然而,根据本发明也可以使用其他数据流系统。在方框200中,对于诸如视频文件的数字文档由用户发出请求。尽管也可以使用其他设备(例如,电话),但最好通过用户使用置顶盒8产生视频请求。该视频请求从CPE单元2发送经由DSLAM 9路由的、通过ATM交换机(或网络)10并由视频服务器22接收。在方框201中,NCS 11执行网络管理功能(例如,根据用户访问权和请求来设置和取消虚拟电路)以控制对内容的访问。
在方框202中,所述视频发送到CPE 2。从位于服务提供商网络中的视频服务器22向在由NCS 11设置的ATM虚拟电路上的CPE 2发送视频数据流。该视频数据流离开视频服务器22并进入ATM首端网络1、进入DSLAM9、然后在CPE 2处被接收。CPE 2能够向包含视频解码器的置顶盒8发送视频。在方框203中,填满缓冲器34,以便提供对于再同步的延迟或修复在网络1中的物理链接中的其他故障。最好在视频发送到用于解码的置顶盒解码器8和显示器之前填满缓冲器34。
如果DSL调制解调器30丢失物理层同步,则视频流不再能够通过网络从视频服务器22向拥护侧设备2发送,以及导致服务中断。如果物理层同步丢失,则利用信令机制装置来警告NCS 11、DSLAM 9和CPE 2。在方框204中,在DSLAM 9处检测物理层信号的丢失,并且DSLAM 9向NCS 11传送消息或信号。在方框205中,NCS 11检查以了解用户目前是否正在接收点播流内容。当用户正接收点播流内容时,在方框206中,DSLAM 9正试图再同步DSL调制解调器物理层。如果用户正接收点播流内容,则在方框207中,NCS 11准备通知视频服务器22什么时候已经发生再同步。
一旦在CPE 2处检测到物理层信号的丢失,在方框208中,CPE 2可以通知置顶盒8使解码器减慢速度且以较慢的速率(为了容许必要的延迟,例如,为了容许缓冲器34以较低的速率腾空)对视频解码,或者CPE 2将以正常速率或如果必要以较低的速率来继续腾空连接到置顶盒8的缓冲器34。
一旦在DSLAM 9和CPE 2处发生再同步,在方框209中,启动来自视频服务器22的增加数据速率。CPE 2向NCS 11发送指示在缓冲器34中存储的最后单元的消息。NCS 11向视频服务器22通知最后单元信息,然后视频服务器22增加速率,所述流内容以该速率发送到CPE 2上的缓冲器34。流内容将在一时间周期内以较高的速率从视频服务器22发送到CPE 2上的缓冲器34。对于较高速率的时间周期主要取决于视频服务器22和CPE 2之间可用的带宽。所以,在方框210中,一旦在CPE 2处填满缓冲器34,CPE 2向NCS 11发送指示缓冲器34填满的消息,并且视频服务器22需要返回来以正常的速率发送流内容。NCS 11通知视频服务器22缓冲器34填满,然后视频服务器22将恢复以合适的速率发送流内容。继续数据流直到满足服务请求为止。
已经说明流数据传送系统中物理层恢复的优选实施例(该实施例是说明的目的而不是限定性的),注意到本领域的技术人员根据以上示教能够进行修改和变化。所以可以理解在本发明公开的特定实施例中可以进行变化,其是在如附加的权利要求所概述的本发明的范围和精神之内。所以已经详细和按照专利法特定要求来说明了本发明,要求和期望由专利证书保护的本发明阐明在附加的权利要求中。
Claims (17)
1.一种异步传输模式数字文档传送系统,包括:
用户侧单元(2),其配置来容许用户定购和接收数据流;
缓冲器(34),其耦合到用户侧单元(2),以便在向用户发送数据流之前存储数据流;
服务器(22),其具有存储其上的通过交换ATM网络(100)传送给用户的数字文档;和
耦合到服务器(22)和用户侧单元(2)的网络控制系统(11),用于控制在服务器(22)和缓冲器(34)之间的数据流的数据速率,以确保在服务器(22)和用户侧单元(2)之间的物理层丢失的期间维持从用户侧单元(2)到用户的稳定数据流。
2.如权利要求1所述的文档传送系统,其中用户侧单元(2)包括其中的缓冲器(34),该缓冲器(34)包括足够的存储器存储容量来维持到达用户的数据流一段时间。
3.如权利要求2所述的文档传送系统,其中所述一段时间包括恢复物理层需要的时间。
4.如权利要求2所述的文档传送系统,其中所述一段时间可达30秒。
5.如权利要求1所述的文档传送系统,还包括在用户侧单元(2)和网络控制系统(11)之间耦合的多路复用器(9),所述多路复用器(9)包括信令机制装置(35)以向至少一个组件报警丢失物理层。
6.如权利要求5所述的文档传送系统,还包括在网络控制系统(11)、用户侧单元(2)和多路复用器(9)之间设置的虚拟电路以使在它们之间能够进行通信。
7.如权利要求1所述的文档传送系统,其中服务器(22)配置用来在物理层已经恢复后以大于正常速率的速率传送数据流。
8.如权利要求7所述的文档传送系统,其中服务器(22)配置用来在缓冲器已经填满后以正常速率传送数据流。
9.如权利要求1所述的文档传送系统,其中用户侧单元(2)配置用来当丢失物理层时以小于正常速率的速率传送数据流。
10.一种用于在异步传输模式网络上维持数据流的方法,该方法包括步骤:
提供步骤(202),提供配置来容许用户接收数据流的用户侧单元(2);
存储步骤(203),在向用户发送数据流之前在缓冲器(34)中存储一部分数据流;
发送步骤(205),通过交换异步传输模式网络(100)从服务器(22)发送数据流;以及
控制步骤,控制在服务器(22)和缓冲器(34)之间的数据流的数据速率,以确保在服务器(22)和用户侧单元(2)之间的物理层的丢失期间维持从用户侧单元(2)到用户的稳定数据流,
其中控制数据流的数据速率的步骤包括维持步骤(208),在缓冲器(34)中维持来自数据流的数据量,以便在丢失物理层后的一段时间保持到达用户的数据流。
11.如权利要求10所述的方法,其中所述一段时间包括恢复物理层需要的时间。
12.如权利要求10所述的方法,其中控制步骤(208或209)包括使用耦合到服务器(22)和用户侧单元(2)的网络控制系统(11),该网络控制系统(11)提供从服务器(22)到用户侧单元(2)的数据流的数据速率的控制。
13.如权利要求12所述的方法,还包括在用户侧单元(2)和网络控制系统(11)之间耦合的多路复用器(9),以及还包括报警步骤(204):当丢失物理层时,从多路复用器(9)发信号向至少一个组件报警丢失物理层。
14.如权利要求12所述的方法,还包括设立步骤(201):在网络控制系统(11)、用户侧单元(2)和多路复用器(9)之间设立虚拟电路,以便能够在它们之间进行通信。
15.如权利要求10所述的方法,还包括传送步骤(210):在已经恢复物理层后,以大于正常速率的速率从服务器传送数据流。
16.如权利要求15所述的方法,还包括传送步骤(210):在已经填满缓冲器后,以正常速率传送数据流(210)。
17.如权利要求10所述的方法,还包括传送步骤(208):当丢失物理层时,以小于正常速率的速率将数据流从用户侧单元(2)传送给用户。
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- 2003-01-10 JP JP2003560767A patent/JP4159475B2/ja not_active Expired - Fee Related
- 2003-01-10 KR KR1020047010841A patent/KR100921162B1/ko active IP Right Grant
- 2003-01-10 EP EP03703776A patent/EP1464003B1/en not_active Expired - Fee Related
- 2003-01-10 AU AU2003205108A patent/AU2003205108A1/en not_active Abandoned
- 2003-01-10 WO PCT/US2003/000872 patent/WO2003060741A1/en active Application Filing
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Also Published As
Publication number | Publication date |
---|---|
JP4159475B2 (ja) | 2008-10-01 |
CN1633653A (zh) | 2005-06-29 |
KR20040074117A (ko) | 2004-08-21 |
US20030135544A1 (en) | 2003-07-17 |
KR100921162B1 (ko) | 2009-10-13 |
EP1464003B1 (en) | 2011-10-05 |
EP1464003A1 (en) | 2004-10-06 |
US7512650B2 (en) | 2009-03-31 |
EP1464003A4 (en) | 2009-07-22 |
AU2003205108A1 (en) | 2003-07-30 |
JP2005515671A (ja) | 2005-05-26 |
WO2003060741A1 (en) | 2003-07-24 |
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