CN101197594A - 用于确定网络中的微反射的方法和装置 - Google Patents

用于确定网络中的微反射的方法和装置 Download PDF

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CN101197594A
CN101197594A CNA2007101988155A CN200710198815A CN101197594A CN 101197594 A CN101197594 A CN 101197594A CN A2007101988155 A CNA2007101988155 A CN A2007101988155A CN 200710198815 A CN200710198815 A CN 200710198815A CN 101197594 A CN101197594 A CN 101197594A
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frequency
test
little reflection
network element
testing
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罗伯特·J·汤普森
迈克尔·J·库珀
查尔斯·S·穆尔
约翰·L·莫兰三世
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Arris Technology Inc
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    • G06F15/163Interprocessor communication
    • G06F15/173Interprocessor communication using an interconnection network, e.g. matrix, shuffle, pyramid, star, snowflake
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Abstract

通过确定来自放大器和双工滤波器阻抗失配的微反射和来自分接电缆阻抗失配的微反射,来确定微反射的存在。通过指令网元以关于放大器和双工滤波器阻抗失配的第一符号率和第一分辨率、以及以关于来自分接电缆阻抗失配的微反射的第二符号率的第二频率和第二分辨率来发射测试信号,以确定来自阻抗失配的微反射。以数个频率执行测试,并且识别具有最小微反射的信道。

Description

用于确定网络中的微反射的方法和装置
技术领域
本公开涉及确定网络中的微反射。更具体地,本公开涉及确定HFC网络中的上游通信中的微反射以允许传输信道的最优选择。
背景技术
同轴电缆电视系统已被广泛地使用了许多年,并且已经发展了广大的网络。电缆操作员常常难于管理和监视广大和复杂的网络。典型的电缆网络一般包含通常连接到数个节点的头端,节点向包含数个接收机的电缆调制解调器终端系统(CMTS)提供内容,每个接收机连接到许多个订户的数个调制解调器,例如,单个接收机可以连接到数百个调制解调器。在许多情况中,数个节点可以服务于城镇或城市的特定区域。调制解调器经由专用频带上的上游通信与CMTS通信。
而且,电缆网络日益增加着承载需要高的服务质量和可靠性的信号,诸如语音通信或者IP语音(VoIP)通信。语音或数据业务的任何中断是极为不便的,并且对于订户而言常常是不可接受的。多种因素可能影响服务质量,包括上游信道的质量。影响上游通信的质量的一个因素是通信信号的微反射的存在。
微反射是通信信号的复本,诸如反射回到其自身但是时间上延迟的信号。存在两个引起上游HFC设施中的微反射的显著诱因,阻抗失配和双工滤波器。显著的微反射可以使上游HFC设施性能劣化。准确地诊断微反射问题典型地需要技术人员或工程人员处于HFC设施中的多个位置并且同时在可疑设备位置处注入测试信号。然后使用专用测试仪器,诸如矢量信号分析仪,在头端位置处检测微反射的存在。该诊断过程需要大量的人工操作,常常需要驱车到达设施中的远程位置或者专用测试仪器。该诊断过程也是耗时的和昂贵的。因此,需要一种确定微反射是否使上游HFC设施性能略微劣化的自动化过程,其不会显著影响HFC网络,是成本有效的,并且不需要专用仪器。
发明内容
本公开描述了一种自动化过程:利用终端设备(诸如MTA或电缆调制解调器)并结合经由CMTS设备在头端处进行的测量,确定微反射是否使上游HFC设施性能略微劣化,并且其不需要驱车到达设施中的远程位置。
根据本发明的原理,本发明的装置可以包括:微处理器,其被配置以向网元提供指令以调谐到测试频率并且以测试符号率来发射测试信号;接收机,其被配置以自网元接收测试信号;和均衡器,其被配置以测量接收的测试信号中包含的微反射,其中微处理器被配置以基于被测的微反射来确定与网元通信的最优通信信道。
在该装置中,可以指令以预定的分辨率发射所述测试信号,并且其可以约为2560ksym/s,预定的分辨率约为390ns。测试符号率可以约为5120ksym/s,并且预定分辨率可以约为195ns。
在该装置中,微处理器可以重复地指令网元调谐到另一频率并且发射测试信号直至测试过所有可用的上游频率。还可以进一步将微处理器配置以指令网元发射具有第二符号率的第二测试信号,第二测试信号具有比第一测试信号高的符号率。
在该装置中,微处理器可以进一步被配置以确定离开被测的微反射的源的距离。
根据本发明的一种用于监视网络的方法可以包括以下步骤:选择网元作为测试网元;指令所述测试网元以作为测试频率的第一频率f1和测试符号率来发射测试信号;通过测量由测试网元发射的测试信号中的微反射,来测量测试频率上的微反射;指令测试网元在作为测试频率的第二频率上发射测试信号;重复测量步骤,即通过测量由测试网元发射的测试信号中的微反射,测量作为第二频率的测试频率上的微反射;并且基于作为第一频率和第二频率的测试频率上的微反射,确定用于通信的最优频率信道。
测量微反射的步骤可以包括:测量由网络中的放大器和双工滤波器中的阻抗失配引起的微反射。可以在约2560ksym/s的测试符号率以及约390ns的分辨率,发射测试信号。
测量微反射的步骤可以包括:测量由网络中的分接电缆中的阻抗失配引起的微反射。可以在约5120ksym/s的测试符号率以及约195ns的分辨率,发射测试信号。
该方法可以进一步包括重复如下步骤:指令测试网元在被选为测试频率的另一频率上发射测试信号;并且测量微反射,直至作为测试频率测试过多个可用上游频率信道。
该方法可以进一步包括将另一网元选为测试网元的步骤,并且重复如下步骤:指令测试网元在作为测试频率的第二频率上发射测试信号;并且测量微反射,直至测试过电缆调制解调器终端系统的网络端口上的多个网元和多个可用上游频率信道。
该方法可以进一步包括以下步骤:基于信号和对应的微反射之间的延迟时间和网络中的电缆的传播速度因子,估计网络中的微反射源的位置。
根据本发明的一种计算机可读介质可以承载用于计算机执行监视网络的方法的指令,该方法包括以下步骤:选择网元作为测试网元;指令所述测试网元在作为测试频率的第一频率f1和测试符号率发射测试信号;通过测量由测试网元发射的测试信号中的微反射,测量测试频率上的微反射;指令测试网元在作为测试频率的第二频率上发射测试信号;重复测量步骤,即通过测量由测试网元发射的测试信号中的微反射,测量作为第二频率的测试频率上的微反射;并且基于作为第一频率和第二频率的测试频率上的微反射,确定用于通信的最优频率信道。
在该计算机可读介质中,该指令可以进一步包括重复如下步骤:指令测试网元在被选为测试频率的另一频率上发射测试信号;并且测量微反射,直至作为测试频率测试过多个可用上游频率信道。
在该计算机可读介质中,该指令可以进一步包括将另一网元选为测试网元的步骤,并且重复如下步骤:指令测试网元在作为测试频率的第二频率上发射测试信号;并且测量微反射,直至测试过电缆调制解调器终端系统的网络端口上的多个网元和多个可用上游频率信道。
在该计算机可读介质中,该指令可以进一步包括执行如下步骤:基于信号和对应的微反射之间的延迟时间和网络中的电缆的传播速度因子,估计网络中的微反射源的位置。
本领域的技术人员应认识到,本发明的技术允许操作员自动地确定上游通信信道中的微反射,而不需要将测试仪器远程安置在电缆设施中。此外,本发明中描述的技术不需要将操作员或技术人员分派到HFC网络中的远程位置。通过使用现有的终端设备(具体地,DOCSIS终端设备,诸如MTA和电缆调制解调器)以及头端仪器(具体地,DOCSIS CMTS)可以实现所有的测量。准确了解微反射将使操作员能够更加高效地利用其网络的可用资源,诸如通过切换到具有较小的微反射的通信信道,或者通过更换其中引入了微反射的网络部件以改善信号质量和网络速度。
此外,该过程将使上游HFC设施中的微反射性能最优化。该过程仅使用DOCSIS终端设备,结合在头端处经由DOCSIS CMTS设备进行的测量,并且不需要驱车到达设施中的远程位置或者专业测试仪器。
附图说明
下面的附图用于说明本发明的原理。
图1示出了根据本发明的原理的示例性网络。
图2示出了有助于理解本发明的示例性CMTS 10的逻辑架构。
图3示出了有助于理解本发明的接收机群组201的逻辑配置。
图4示出了示例性网元8,诸如电缆调制解调器。
图5示出了根据本发明的原理的示例性过程。
图6示出了用于执行放大器双工滤波器阻抗失配测试的示例性过程。
图7示出了用于执行分接电缆阻抗失配测试的示例性过程。
具体实施方式
本公开提供了CMTS服务群组中的终端设备的微反射的远程评估,以及用于以改善的微反射性能来最优地将服务群组重新指配到占线信道的装置。在对于网元可用的全部的占线信道上,CMTS服务群组中的所有网元的微反射评估可以提供微反射电平的映射,所述网元诸如电缆调制解调器、机顶盒和媒体终端适配器(MTA)以及DOCSIS(电缆数据传输系统)终端设备。该方法开始于询问CMTS服务群组中的网元以获得其在占线信道范围上的微反射性能。微反射映射用于确定最优的占线信道,最优的占线信道被定义为具有出现最少量的最差情况微反射的信道。为了评估上游HFC设施中可能存在的全范围的微反射条件,优选地使用两个符号率。第一低速率的符号率,例如2560ksym/sec,用于识别由放大器双工滤波器生成的微反射,而第二较高速率的符号率,例如5120 ksym/s,用于识别由本地分接电缆阻抗失配生成的微反射。该过程可以重复,直至使所有CMTS服务群组最优化。优选地,微反射测试不应与网络中的其他改变一同出现,诸如光学路由改变、入口电平切换或者将可能引起RF电平不稳定的任何其他的程序或事件。
为了确保在网络中存在足够的功率容限用于执行本发明中的测试,操作员应了解可用的上游频率区的上游功率谱。该知识可以有助于在不影响HFC性能和订户服务的情况下,协助测试信道安置和添加额外的测试信道功率的能力。该知识还可以向操作员提供信心,即可能由不足的功率容限引起的失真不会影响执行的测试。尽管可以使用用于确定网络中的可用功率容限的任何适当的方法,但是在2006年10月20日提交的、受让的U.S.Serial No.11/551,014的、标题为“METHODAND APPARATUS FOR DETERMINING THE TOTAL POWERMARGIN AVAILABLE FOR AN HFC NETWORK”的、No.BCS04121Attorney Docket的共同受让的公开中,描述了一种方法,通过引用将其整体内容并入于此。
在2006年9月5日提交的、受让的U.S.Serial No.11/470,034的、标题为“METHOD AND APPARATUS FOR GROUPING TERMINALNETWORK DEVICES”的、No.BCS04122 Attorney Docket的共同受让的公开中,提供了一种用于使驻留在相同光学节点或者服务群组上的设备隔离的方法,通过引用将其整体内容并入于此。
图1示出了示例性网络,其中多个终端网元8(例如,电缆调制解调器、机顶盒、配备有机顶盒的电视机、或者诸如HFC网络的网络上的任何其他网元)通过节点12和一个或多个抽头(未示出)连接到位于头端14中的电缆调制解调器终端系统(CMTS)10。在示例性配置中,头端14还包含光学收发信机16,其通过光纤向多个节点12提供光学通信。CMTS 10连接到IP或PSTN网络6。本领域的技术人员应认识到,可以存在多个连接到头端的节点12,并且头端可以包含多个CMTS 10单元,每个CMTS 10单元包含多个接收机(例如,8个接收机),每个接收机与多个(例如100个)网元8通信。CMTS 10还可以包含备用接收机,其未被连续配置到网元8,而是可以选择性地配置到网元8。在2005年6月30日提交的、标题为“Automated Monitoringof a Network”的、受让的U.S.Serial No.11/171,066的共同受让的Attorney Docket No.BCS03827中,描述了备用接收机的使用,通过引用将其整体内容并入于此。
图2示出了有助于理解本发明的示例性CMTS 10的逻辑架构。如图2中说明的,CMTS 10可以包含处理单元100,其可以接入RAM 106和ROM 104,并且可以控制CMTS 10的操作和通过网元8发送到CMTS10的RF通信信号。处理单元100优选地包含微处理器102,其可以自ROM 104或RAM 106接收信息,诸如指令和数据。处理单元100优选地连接到显示器108,诸如CRT或LCD显示器,其可以显示状态信息,诸如是否正在执行站维护(SM)或者接收机是否需要负载均衡。输入键盘110也可以连接到处理单元100,并且可以允许操作员向处理器100提供指令、处理请求和/或数据。
RF收发信机(发射机/接收机)单元优选地包含多个发射机4和接收机2,用于通过光学收发信机16、节点12和多个网络抽头(未示出)向多个网元8提供双向通信。本领域的技术人员应认识到,CMTS10可以包含多个RF接收机2,例如8个RF接收机和备用接收机。每个RF接收机2可以支持超过100个网元。RF接收机2,诸如Broadcom3140接收机(接收机)优选地向均衡器103提供接收的RF信号,均衡器103用于获取均衡器值和突发调制错误比(MER)测量结果、分组错误率(PER)和比特错误率(BER)。均衡器103优选地是多抽头线性均衡器(例如,24抽头线性均衡器),其还可以被称为前馈均衡器(FFE)。均衡器103可以集成包含在RF接收机2中,或者可以是分立的设备。RF接收机2还可以包括FFT模块308,用于支持功率测量。每个接收机2的通信特性可以存储在ROM 104或者RAM 106上,或者可由外部源,诸如头端14提供。RAM 104和/或ROM 106还可以承载用于微处理器102的指令。
图3示出了有助于理解本发明的接收机群组201的逻辑配置。如图3中说明的,备用接收机204可以以非侵入的方式接入每个主接收机端口220(例如,R0~R7)。如所说明的,提供了CMTS接收机端口220,其可以具有Amphenol连接器的形式,以允许电缆,例如同轴电缆(未示出)与主接收机2连接。
备用接收机204优选地经由信号线222接入主接收机端口220的信号线221,并且抽头优选地位于来自接收机端口220的电缆信号进入接收机201的位置,因此连接的主接收机201和备用接收机204可以接收相同的信号。本领域的技术人员应认识到,每个主接收机201(例如接收机R0~R7)根据不同的通信特性接收信号,例如,不同的频率(RF频带)和通信协议上的通信。备用接收机204优选地可调谐到每个主接收机201的RF频带。优选地,备用接收机204一次仅与一个主接收机201连接(矩阵)。
当电缆操作员开始测试操作时,他们可以选择任何寄存的调制解调器,或者CMTS 10可以为他们选择调制解调器。一旦选择了调制解调器,则将其移动(调谐频率)到备用接收机,向其传递测试数据并且测量结果。一旦完成了测试测量,则使调制解调器移动回到(指令其重新调谐至主接收机频率)其原始主接收机。该整体过程优选地是在调制解调器未从网络解除寄存的情况下执行的,以避免中断订户的服务或者主接收机上的针对其他订户的任何其他服务。
在优选实现方案中,本发明可以使用DOCSIS网元,诸如电缆调制解调器,生成微反射测试信号。因此,可以使用一个可用的上游DOCSIS带宽实现测试信号,例如200kHz、400kHz、800kHz、1600kHz、3200kHz或6400kHz。在双工器滚降较突出的上频带边缘处,优选的实现方案可以使用的窄的800kHz带宽,这是因为窄的带宽使返回路径中的所需干净频谱量最小,并且在准许可用频谱的情况中使用较宽的带宽,以便于获得测量中的改善的分辨率。
图4示出了示例性网元8,诸如电缆调制解调器。网元8优选地包含处理器302,其可以与RAM 306和ROM 304通信,并且其控制网元的一般操作,包括网元根据来自CMTS 10的指令发送的预均衡参数和通信的前导长度。网元8还包含收发信机(其包括发射机和接收机),其提供与CMTS 10的双向通信。网元8还可以包含均衡器单元,其可以使针对CMTS 10的通信均衡。网元8还可以包含衰减器320,其可由微处理器控制,用于使待发射的信号衰减到所需的功率电平。本领域的技术人员应认识到,仅出于讨论的目的分立地示出了网元8的部件,但是实际上可以将多种部件组合。
在图5~7中示出了用于自动地确定服务群组中的微反射的示例性过程,其可以与节点相关联。如图5的步骤S1中说明的,开始微反射映射过程,以及步骤S3,选择服务群组端口。微反射映射过程的一个部分包括,执行低符号率测试(例如,2560Ksym/s),其优选地测试放大器和双工滤波器中的阻抗失配,即步骤S5。微反射映射过程的另一部分可以包括,执行高符号率测试(例如,5120Ksym/s),其优选地测试分接电缆阻抗失配,即步骤S7。本领域的技术人员应认识到,如果测试信号是2560Ksym/s,则每个占用信道将使用3.2MHz的带宽,并且如果测试信号是5120Ksym/s,则每个占用信道将使用6.4MHz的带宽。优选地执行这两个分立的测试以在不同的分辨率下分析网络。然而,由于5-42MHz频谱仅能够包含六个信道(38.4MHz占用带宽),因此高符号率测试(例如,5120Ksym/s)是足够的。然而,2560Ksym/s测试信号提供了调查对于高符号率测试不够宽(宽度小于6.4MHz)的频隙的机会。
更具体地,由于均衡器抽头典型地均匀间隔,因此抽头之间的间距与反射的时间和物理距离成比例。本领域的技术人员应认识到,微反射的出现在时间上晚于其原始信号,并且因此具有与其相关的延迟。本领域的技术人员还应认识到,符号率翻倍(例如,从2560Ksym/sec到5120Ksym/sec),均衡器抽头之间的时间增量减少一半(例如,从390nsec到195nsec),因此使均衡器执行的测量的分辨率翻倍。可以基于反射事件的行进时间和电缆的传播速度因子(例如,RG-6同轴电缆是1.2ns每英尺)来确定微反射源的位置。例如,如果微反射的时间延迟是195.3ns,则使该延迟除以2,以提供从源到终端网元的、横越同轴电缆以产生微反射的的时间(例如,195.3ns/2=97.65ns),并且随后除以传播速度因子1.2ns/ft,提供距离网元(例如,位于本地的双向分流器)81.4ft的微反射的估计。
在步骤S9中,该过程确定是否存在更多的端口可用于测试,如果是,则将测试端口变为另一端口,即步骤S11。如果不存在可用的更多端口,即步骤S9中的答案为否,则在步骤S13,优选地通过列出对于与所执行的阻抗失配测试相关联的多种频率而识别的微反射电平,映射在放大器双工滤波器阻抗失配测试和/或分接电缆阻抗失配测试中确定的微反射电平。使用映射的微反射电平,识别最优的操作RF信道频率,即步骤S15。
最优的操作RF信道选择优选地基于被测的微反射电平(MRL),并且可以通过关于每个发射频率信道而建立的独立均衡器系数值的分级系统而执行。尽管可以使用任何适当的分级,但是表1中示出了微反射分级的示例性顺序。
    信道   Mag1stMRL(dB)     TapLoc 1s tMRL   Mag2ndMRL(dB)     TapLoc 2ndMRL
    123456   414137332521     331254   434341352729     175583
表1示出了出于讨论目的通过执行分接电缆阻抗失配测试被测的示例性微反射电平。如所说明的,该分级可以包括最大的被测MRL量值,其被标为Mag1stMR,以及第一最大MRL抽头位置。该分级还可以列出第二最大的被测MRL的量值,其被标为Mag2ndMRL,以及第二MRL的抽头位置。
本领域的技术人员应认识到,MRL表示信号功率与微反射功率的比,其通过查看均衡器系数而确定。例如,信号功率是出现在均衡器系数矩阵的“中心”或“主”抽头中的功率。微反射功率是其他均衡器系数(非主抽头)中出现的所有功率的和。表1包含信号功率和微反射功率之间的比的dB表示(例如,10*log10(信号功率/微反射功率))。非常大的数值(例如41)意味着,微反射相比于信号功率是非常小的。非常小的数值(例如21)意味着相对于信号电平的大的微反射功率。本领域的技术人员应认识到,通过通过利用与主抽头最接近的抽头位置来选择信道,电缆调制解调器将通过预均衡补偿微反射的可能性增加。按照优选顺序对表1中的信道分类,信道1是最好的,而信道6是最差的。
具有最低微反射电平(最高MRL)的信道可被选为用于承载具有5120Ksym/s的符号率的数据的最优信道。例如,具有第一MRL的最高量值的信道是第一优选操作RF信道。具有与第一信道相等电平的第一和第二MRL、但是具有离开抽头的较大的微反射距离的信道是第二优选操作RF信道,如表1中说明的信道2。在与主抽头最接近的抽头处的具有第三最高MRL(因此具有最接近的距离和均衡器抽头)的RF信道是第三优选操作RF信道。具有低于或等于第三优选信道的MRL但是在时间(均衡器抽头和距离)上离开主抽头更远的RF信道是第四优选操作RF信道。具有低于或等于第四优选信道的MRL但是在时间(均衡器抽头和距离)上离开主抽头更远的RF信道是第五优选操作RF信道。具有低于第五信道的第一MRL但是具有高于第五信道的第二MRL的RF信道是第六优选信道。具有低于或等于第(n-1)优选信道的MRL但是在时间(均衡器抽头和距离)上离开主抽头更远的RF信道是第n优选或最低优选操作RF信道。
本领域的技术人员应认识到,对于在执行放大器双工滤波器阻抗失配测试时进行的测量,即步骤S5,可以创建相似的表格。该表格基本上与上文所述相同,不同之处在于,现在测试信号是2560Ksym/s,并且头端中的可用频隙的数目从6个可用信道增加到12个可用信道。2560Ksym/s测试的结果将导致基于上文的标准以MRL顺序分级的12个可用信道。
组合这两个表格将向操作员提供对于一个6.4MHz(5120Ksym/sec)或者两个3.2MHz(2560Ksym/sec)信道来选择使用CMTS10上的特定的收发信机频隙的基本原则。然后,可以规划整个5-42MHz返回频谱,以基于它们的微反射损害环境,最大化地利用6.4MHz(5120Ksym/s)和3.2MHz(2560Ksym/s)信道的混合。
图6示出了用于执行放大器双工滤波器阻抗失配测试的示例性过程。在步骤S50中开始该测试,并且在测试分辨率1下将符号率设定为测试率1,即步骤S52。在优选实现方案中,测试率1可以处于2560Ksym/sec的符号率下,分辨率为390ns。选择端口上的网元NE并且选择测试信道频率Ft,诸如最低频率信道位置,即步骤S54。将选定网元调谐到选定频率并且指令其自选定网元发射测试信号,即步骤S56。在步骤S58中,在头端处,诸如通过测量MER、PER和/或BER、以及CMTS中包含的均衡器系数,估计接收自选定网元的返回信号。优选地,由备用接收机接收来自网元的返回信号,并且使均衡器与备用接收机相关联。在步骤S60中,如果存在更多的占线上游信道,则将信道频率Ft变为另一信道频率,作为测试信道频率,即步骤S62。如果在步骤60中不存在更多的信道,即步骤62为“否”,则在步骤64中确定是否存在更多的网元,如果在步骤64中为“是”,即存在更多的网元,则选择另一网元并且指配第一测试频率Ft。在步骤S68中记录在测试过程中识别的微反射。在每个频率增量处测量MER、PER和/或BER以及均衡器系数,并且对于MER、PER或BER和均衡器系数的劣化,监视返回路径信号。
图7示出了用于执行分接电缆阻抗失配测试的示例性过程。在步骤S70中开始该测试,并且在测试分辨率2下将符号率设定为测试率2,即步骤S72。在优选实现方案中,测试率2可以处于5120Ksym/s的符号率下,分辨率为195ns。选择端口上的网元NE并且选择测试信道频率Ft,诸如最低频率信道位置,即步骤S74。将选定网元调谐到选定频率并且指令其自选定网元发射测试信号,即步骤S76。在步骤S78中,在头端处,诸如通过测量MER、PER和/或BER以及CMTS中包含的均衡器系数,估计接收自选定网元的返回信号。优选地,由备用接收机接收来自网元的返回信号。在步骤S80中,如果存在更多的占线上游信道,则将信道频率Ft变为另一信道频率,作为测试信道频率,即步骤S82。如果不存在更多的信道,在步骤80中为“否”,则在步骤84中确定是否存在更多的网元。如果在步骤84中为“是”,即存在更多的网元,则选择另一网元并且指配第一测试频率Ft。在步骤S88中记录在测试过程中识别的微反射。在每个频率增量处测量MER、PER和/或BER以及均衡器系数,并且对于MER、PER或BER和均衡器系数的劣化,监视返回路径信号。
CMTS备用接收机优选地用于获得错误率和微反射测量结果,以避免影响提供给消费者的服务。在使用备用接收机时,返回通信信道可以是占线的,因此避免了在操作员希望执行测试时占线服务中断。可替换地,可以使用另一接收机通过采用“离线”方式或者通过调节正常服务引起的影响而进行测量。
图5~7中的过程可以以硬连线设备、固件或者在处理器中运行的软件中实现。用于软件或固件实现方案的处理单元优选地包含于CMTS中。图5~7中说明的任何过程可以包含在计算机可读介质上,其可由微处理器102读取。计算机可读介质可以是能够承载微处理器执行的指令的任何介质,包括CD光盘、DVD光盘、磁盘或光盘、磁带、硅基可移动或者不可移动的存储器、分组或未分组的有线或无线传输信号。
本发明使得技术人员或工程人员能够在中心位置,诸如头端,来诸如通过使用Motorola BSR64000廉价地和快速地远程分析上游通信信道,而非使用外部测试仪器(诸如矢量信号分析仪)并且将技术人员部署到电缆设施中的多种位置。本发明还使得能够在不影响占线服务的情况下执行测试。通过使用现有的终端设备(具体地,DOCSIS终端设备,诸如MTA和电缆调制解调器)以及头端设备(具体地,DOCSISCMTS)可以实现所有测量。
本领域的技术人员应认识到,本发明的技术允许操作员自动地确定上游通信信道中的微反射,不需要将测试仪器远程安置在电缆设施中。此外,本发明中公开的技术不需要将操作员或技术人员分派到HFC网络中的远程位置。通过使用现有的终端设备(具体地,DOCSIS终端设备,诸如MTA和电缆调制解调器)以及头端仪器(具体地,DOCSISCMTS)可以实现所有的测量。准确了解微反射将使操作员能够更加高效地利用其网络的可用资源,诸如通过切换到具有较小的微反射的通信信道,或者通过更换其中引入了微反射的网络部件以改善信号质量和网络速度。

Claims (23)

1.一种用于监视网络的装置,包括:
微处理器,其被配置以向网元提供指令以调谐到测试频率并且在测试符号率下发射测试信号;
接收机,其被配置以自网元接收测试信号;和
均衡器,其被配置以测量接收的测试信号中包含的微反射,
其中所述微处理器被配置以基于被测的微反射来确定与所述网元通信的最优通信信道。
2.如权利要求1所述的装置,其中所述的测试信号被指令以预定的分辨率发射。
3.如权利要求2所述的装置,其中所述的测试符号率约为2560ksym/s,并且所述预定的分辨率约为390ns。
4.如权利要求2所述的装置,其中所述的测试符号率约为5120ksym/s,并且所述的预定的分辨率约为195ns。
5.如权利要求2所述的装置,其中所述的微处理器重复地指令网元调谐到另一频率并且发射测试信号直至测试过所有可用的上游频率。
6.如权利要求1所述的装置,其中所述的微处理器被进一步配置以指令所述网元发射具有第二符号率的第二测试信号,所述第二测试信号具有比所述第一测试信号高的符号率。
7.如权利要求1所述的装置,其中所述的微处理器被进一步配置以确定离开被测的微反射的源的距离。
8.一种用于监视网络的方法,包括步骤:
选择网元作为测试网元;
指令所述测试网元以作为测试频率的第一频率f1和测试符号率来发射测试信号;
通过测量由所述测试网元发射的测试信号中的微反射,来测量所述测试频率上的微反射;
指令所述测试网元以作为测试频率的第二频率来发射测试信号;
重复所述测量步骤,通过测量由所述测试网元发射的测试信号中的微反射,来测量作为第二频率的测试频率上的微反射;以及
基于作为所述第一频率和所述第二频率的所述测试频率上的微反射,来确定用于通信的最优频率信道。
9.如权利要求8所述的方法,其中测量微反射的步骤包括:测量由网络中的放大器和双工滤波器中的阻抗失配引起的微反射。
10.如权利要求9所述的方法,其中以约2560ksym/s的测试符号率和约390ns的分辨率,发射所述测试信号。
11.如权利要求8所述的方法,其中测量微反射的步骤包括:测量由网络中的分接电缆中的阻抗失配引起的微反射。
12.如权利要求11所述的方法,其中以约5120ksym/s的测试符号率和约195ns的分辨率,发射所述测试信号。
13.如权利要求8所述的方法,进一步包括重复如下步骤:指令所述测试网元在被选为所述测试频率的另一频率上发射所述测试信号;以及测量微反射,直至作为所述测试频率测试过多个可用上游频率信道。
14.如权利要求8所述的方法,进一步包括将另一网元选为测试网元的步骤,并且重复如下步骤:指令所述测试网元在作为测试频率的第二频率上发射测试信号;以及测量微反射,直至测试过电缆调制解调器终端系统的网络端口上的多个网元和多个可用上游频率信道。
15.如权利要求8所述的方法,进一步包括以下步骤:基于信号和对应的微反射之间的延迟时间和网络中的电缆的传播速度因子,估计网络中的微反射源的位置。
16.一种计算机可读介质,其承载有用于计算机执行监视网络的方法的指令,所述方法包括以下步骤:
选择网元作为测试网元;
指令所述测试网元以作为测试频率的第一频率f1和测试符号率来发射测试信号;
通过测量由所述测试网元发射的测试信号中的微反射,来测量测试频率上的微反射;
指令所述测试网元在作为所述测试频率的第二频率上来发射测试信号;
重复所述测量步骤,通过测量由所述测试网元发射的测试信号中的微反射,来测量作为所述第二频率的所述测试频率上的微反射;以及
基于作为所述第一频率和所述第二频率的所述测试频率上的微反射,来确定用于通信的最优频率信道。
17.如权利要求16所述的计算机可读介质,其中测量微反射的步骤包括:测量由网络中的放大器和双工滤波器中的阻抗失配引起的微反射。
18.如权利要求17所述的计算机可读介质,其中以约2560ksym/s的测试符号率以及约390ns的分辨率,发射测试信号。
19.如权利要求16所述的计算机可读介质,其中测量微反射的步骤包括:测量由网络中的分接电缆中的阻抗失配引起的微反射。
20.如权利要求19所述的计算机可读介质,其中以约5120ksym/s的测试符号率以及约195ns的分辨率,发射测试信号。
21.如权利要求16所述的计算机可读介质,进一步包括重复如下步骤:指令测试网元在被选为测试频率的另一频率上发射测试信号;以及测量微反射,直至作为所述测试频率测试过多个可用上游频率信道。
22.如权利要求16所述的计算机可读介质,进一步包括将另一网元选为测试网元的步骤,并且重复如下步骤:指令所述测试网元在作为所述测试频率的第二频率上发射所述测试信号;以及测量微反射,直至测试过电缆调制解调器终端系统的网络端口上的多个网元和多个可用上游频率信道。
23.如权利要求16所述的计算机可读介质,其中所述指令进一步包括执行如下步骤:基于信号和对应的微反射之间的延迟时间和网络中的电缆的传播速度因子,估计网络中的微反射源的位置。
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