缆桥系统可行性分析及信道评估
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摘要
HFC(Hybrid Fiber—Coax,混合光纤—同轴电缆网)是在CATV的基础上发展起来的,适用于已敷设大量同轴电缆用户的地区。由于大多数家庭用户安装了有线电视线路,广播电视运营商将有线电视线路和FTTB(Fiber To The Building,光纤到楼)结合起来,可以有效地降低网络线路建设成本。这使得HFC成为一种灵活而便宜的接入方案,可以与电信的ADSL竞争。
缆桥系统为了实现在有线电视同轴电缆上进行高速数据接入,通过CBSwitch和CB Modem将高速数据调制到CATV同轴电缆的空闲信道上,实现电信网、有线电视网和互联网在同轴电缆上的共用。
目前铺设的有线电视用户分配网络中,所用元件包括分支分配器和同轴电缆执行的标准均由我国广电总局颁布的“中华人民共和国广播电影电视行业标准”规定,但频率范围均为5～1000MHz,1GHz以上的参数没有规定可参考,不同厂家的元件带外参数参差不齐,无标准可言。由于带外缆桥技术在现有的线路上需要传输1000MHz以上的信号,会遇到电缆的传输衰减大,网络上现有的分支器、分配器等设备的插入损耗、反射损耗,以及有源器件放大器的频率响应等多个技术指标不能满足信号传输要求等问题。在信道测试部分,因为带外信道的研究少有前人的研究成果可以作为参考,不论是实验室模拟、实地测量或建立信道模型,都需要进行大量、广泛的细致实验,从而建立一套完全、恰当的实验方法。
本课题是上海市科委“高可信通信网络技术研究与应用”研究课题的子课题。论文的创新之处是在对缆桥系统接入方案进行可行性论证的基础上,建立了缆桥信道完整的数学评估模型,以指导实际缆桥设备的开发和标准的建立。
本文具体工作如下：首先进行现场信道测量工作,并对缆桥信号与CATV信号相互间的干扰影响进行系统分析,以验证缆桥系统接入方案的可行性。在此基础上,采用基于测量的数学建模方法,分别建立了分支分配器和同轴电缆多径反射仿真模型。从模型仿真及拟合结果来看,所建模型能较好地反映出同轴网络信道的基本特性。最后,根据缆桥设备的接入网络特性,确定缆桥接入系统的最佳应用频段。本研究对于实现有线电视网络的高速,优质,多业务工作具有实际意义和应用价值。
HFC is developed on the base of CATV network. HFC technology is suitable for the district which has been installed with a large number of cables. Because most of houses have been installed with CATV cable. Broadcast TV operator combines cable TV network with FTTB to effectively lower the cost of construction. This makes HFC a flexible and cheap access method, which can compete with ADSL of China Telecom.
To achieve high-speed data access, we modulate high-speed data onto the out-of-band frequency of CATV cable through CB Switch and CB Modem and make telecom network, CATV network and Internet coexist on CATV cable. At present, the components of CATV network including distributor, splitter and cable are made in accordance with "The People's Republic of China Radio, Film and Television Industry Standard" which was drafted by Administration of Radio Film and Television. But this standard only covers 5～1000MHz and there is no standard that gives parameter over 1GHz.Different manufactures' components have different parameters on out-of-band frequency. There is no standard to be used as a reference. Because out-of-band CB technology will transfer signal over 1000MHz. Many problems will appear. Because the transmission attenuation is large, present contributor and splitter's insertion loss, reflection loss and frequency response can not meet the need of signal transmission. Thinking of channel test, we should do complete and suitable experiment through massive and extensive work about simulation, field test and building channel model.
The project is a sub-project of Shanghai Science and Technology Commission project'High Reliable Communication Network Technology Research and Application'. Innovation of the thesis is building a complete mathematical estimation model through analyzing feasibility of access solution, which guides development of Cable Bridge and establishment of CB standard.
My work is specified as following:first of all, I field tested the channel and systematically analyzed the mutual interference of CATV and Cable Bridge signal to verify the feasibility of Cable Bridge access solution. On this basis, I built distributor and splitter model as well as cable multi-path reflection model by means of test-based mathematical modeling. To simulation and fitting result, these models can reflect coaxial cable network's basic characteristic well. At last, I determine the most suitable working frequency band of Cable Bridge access system. The research is meaningful and valuable for CATV network to work in a high-speed, high-quality and multi-service way.
缆桥系统为了实现在有线电视同轴电缆上进行高速数据接入,通过CBSwitch和CB Modem将高速数据调制到CATV同轴电缆的空闲信道上,实现电信网、有线电视网和互联网在同轴电缆上的共用。
目前铺设的有线电视用户分配网络中,所用元件包括分支分配器和同轴电缆执行的标准均由我国广电总局颁布的“中华人民共和国广播电影电视行业标准”规定,但频率范围均为5～1000MHz,1GHz以上的参数没有规定可参考,不同厂家的元件带外参数参差不齐,无标准可言。由于带外缆桥技术在现有的线路上需要传输1000MHz以上的信号,会遇到电缆的传输衰减大,网络上现有的分支器、分配器等设备的插入损耗、反射损耗,以及有源器件放大器的频率响应等多个技术指标不能满足信号传输要求等问题。在信道测试部分,因为带外信道的研究少有前人的研究成果可以作为参考,不论是实验室模拟、实地测量或建立信道模型,都需要进行大量、广泛的细致实验,从而建立一套完全、恰当的实验方法。
本课题是上海市科委“高可信通信网络技术研究与应用”研究课题的子课题。论文的创新之处是在对缆桥系统接入方案进行可行性论证的基础上,建立了缆桥信道完整的数学评估模型,以指导实际缆桥设备的开发和标准的建立。
本文具体工作如下：首先进行现场信道测量工作,并对缆桥信号与CATV信号相互间的干扰影响进行系统分析,以验证缆桥系统接入方案的可行性。在此基础上,采用基于测量的数学建模方法,分别建立了分支分配器和同轴电缆多径反射仿真模型。从模型仿真及拟合结果来看,所建模型能较好地反映出同轴网络信道的基本特性。最后,根据缆桥设备的接入网络特性,确定缆桥接入系统的最佳应用频段。本研究对于实现有线电视网络的高速,优质,多业务工作具有实际意义和应用价值。
HFC is developed on the base of CATV network. HFC technology is suitable for the district which has been installed with a large number of cables. Because most of houses have been installed with CATV cable. Broadcast TV operator combines cable TV network with FTTB to effectively lower the cost of construction. This makes HFC a flexible and cheap access method, which can compete with ADSL of China Telecom.
To achieve high-speed data access, we modulate high-speed data onto the out-of-band frequency of CATV cable through CB Switch and CB Modem and make telecom network, CATV network and Internet coexist on CATV cable. At present, the components of CATV network including distributor, splitter and cable are made in accordance with "The People's Republic of China Radio, Film and Television Industry Standard" which was drafted by Administration of Radio Film and Television. But this standard only covers 5～1000MHz and there is no standard that gives parameter over 1GHz.Different manufactures' components have different parameters on out-of-band frequency. There is no standard to be used as a reference. Because out-of-band CB technology will transfer signal over 1000MHz. Many problems will appear. Because the transmission attenuation is large, present contributor and splitter's insertion loss, reflection loss and frequency response can not meet the need of signal transmission. Thinking of channel test, we should do complete and suitable experiment through massive and extensive work about simulation, field test and building channel model.
The project is a sub-project of Shanghai Science and Technology Commission project'High Reliable Communication Network Technology Research and Application'. Innovation of the thesis is building a complete mathematical estimation model through analyzing feasibility of access solution, which guides development of Cable Bridge and establishment of CB standard.
My work is specified as following:first of all, I field tested the channel and systematically analyzed the mutual interference of CATV and Cable Bridge signal to verify the feasibility of Cable Bridge access solution. On this basis, I built distributor and splitter model as well as cable multi-path reflection model by means of test-based mathematical modeling. To simulation and fitting result, these models can reflect coaxial cable network's basic characteristic well. At last, I determine the most suitable working frequency band of Cable Bridge access system. The research is meaningful and valuable for CATV network to work in a high-speed, high-quality and multi-service way.
引文
[1]崔竞飞,高义河,李进.HiNOC—一种适合有线网络双向改造的同轴电缆接入技术.[J].世界宽带网络.2007.(3)：48-50
[2]李彦.通过缆桥接入技术实现三网融合的研究[D].上海：华东师范大学,2007.
[3]万乾荣.HFC网络上的宽带接入技术进展.[J].有线电视技术.2008(4)59-61
[4]林维忠.宽带接入技术综述.[J].数字通信世界.2009(2)44-49
[5]王涛,余少波.基于MoCA的有线电视接入网双向化改造.[J].世界宽带网络.2007(6)：67-70
[6]http://baike.baidu.com/view/1019085.htm
[7]梁艺,冯彦杰.HomePNA接入技术概述[J].通信世界.2001
[8]刘世良。利用HomePNA技术实现家庭宽带上网.[J].电力信息化2006年第4卷第11期88-89
[9]王健,李明.基于MoCA标准的家庭网络[J].信息通信.2008
[10]潘祥斌.载噪比、信噪比、图像质量等级[J].中国有线电视.2001
[11]GYT137-1999,有线电视系统用分支器和分配器(5～1000MHz)入网技术条件和测量方法.[S]
[12]吕洪国.现代网络频谱测量技术.[M].北京：清华大学出版社,2000：1-5
[13]王锡胜.有线电视技术.[M].北京：电子工业出版社,1996：265-268
[14]林丙荣.RF同轴电缆传输系统的设计与维护.[J].有线电视技术.2004(2)
[15]樊昌信.通信原理.[M].北京国防工业出版社2001
[16]MoCA Certification Spetification Revision 0.4
[17]MoCA Certification Test Plan MoCA-DEVICE-CTP-V08
[18]Ladd Wardani.Home networking on coax for video and multimedia
[19]MoCA MAC/PHY Specification v1.0
[20]http://www.ixiacom.com/pdfs/about_us/chinese/Datasheet_400T%201600 T
[21]Jiang Dan and Li Mo. Quality of Service in the home network[C] Inst. of Elec. and Elec. Eng. Computer Society, United States.2008 2nd International Conference on Future Generation Communication and Networking, FGCN 2008.PP 473-476
[22]Ovadia Shlomo. MoCA:Ubiquitous multimedia networking in the home[C] SPIE. United States. Broadband Access Communication Technologies II. United states.2007.Volume 6776.
[23]M.Zimmermann and K.Dostert. A multi-path signal propagation model for the powerline channel in the high frequency range[C].in:Proc.3rd Int.Symp.Powerline Communications and its Applications,Lancaster,U.K.,1999,PP.45-51
[24]Manfred Zimmermann and Klaus Dostert. A multipath model for the
powerline channel[J]. IEEE Transactions, Volume 50, number 4, April 2002.
[25]Francis Berrysmith. A Multi-path Model for the Power Line Channel.,University of Auckland.
[26]SJ/T11138-1997.[S]
[27]易浩勇,汪晓岩,孙荣久等.中压配电网载波通信的多径反射模型研究[J].电力系统通信,2004年,1期.
[28]陈宗仕.电视信号在同轴电缆中的传输.[J].中国有线电视.2007.(21)
[29]张红 陈志国 杨家胜.有线电视宽带电缆接入系统(EoC)测试评估.[J].世界宽带网络.2009年8月71-75
[30]王正林.精通MATLAB科学计算.[M].北京：电子工业出版社,2007.ch10
[31]葛哲学.精通MATLAB.[M].北京：电子工业出版社.2008
[32]1stopt软件http://www.7d-soft.com
[33]郑君里,信号与系统.[M].北京高等教育出版社2005
[2]李彦.通过缆桥接入技术实现三网融合的研究[D].上海：华东师范大学,2007.
[3]万乾荣.HFC网络上的宽带接入技术进展.[J].有线电视技术.2008(4)59-61
[4]林维忠.宽带接入技术综述.[J].数字通信世界.2009(2)44-49
[5]王涛,余少波.基于MoCA的有线电视接入网双向化改造.[J].世界宽带网络.2007(6)：67-70
[6]http://baike.baidu.com/view/1019085.htm
[7]梁艺,冯彦杰.HomePNA接入技术概述[J].通信世界.2001
[8]刘世良。利用HomePNA技术实现家庭宽带上网.[J].电力信息化2006年第4卷第11期88-89
[9]王健,李明.基于MoCA标准的家庭网络[J].信息通信.2008
[10]潘祥斌.载噪比、信噪比、图像质量等级[J].中国有线电视.2001
[11]GYT137-1999,有线电视系统用分支器和分配器(5～1000MHz)入网技术条件和测量方法.[S]
[12]吕洪国.现代网络频谱测量技术.[M].北京：清华大学出版社,2000：1-5
[13]王锡胜.有线电视技术.[M].北京：电子工业出版社,1996：265-268
[14]林丙荣.RF同轴电缆传输系统的设计与维护.[J].有线电视技术.2004(2)
[15]樊昌信.通信原理.[M].北京国防工业出版社2001
[16]MoCA Certification Spetification Revision 0.4
[17]MoCA Certification Test Plan MoCA-DEVICE-CTP-V08
[18]Ladd Wardani.Home networking on coax for video and multimedia
[19]MoCA MAC/PHY Specification v1.0
[20]http://www.ixiacom.com/pdfs/about_us/chinese/Datasheet_400T%201600 T
[21]Jiang Dan and Li Mo. Quality of Service in the home network[C] Inst. of Elec. and Elec. Eng. Computer Society, United States.2008 2nd International Conference on Future Generation Communication and Networking, FGCN 2008.PP 473-476
[22]Ovadia Shlomo. MoCA:Ubiquitous multimedia networking in the home[C] SPIE. United States. Broadband Access Communication Technologies II. United states.2007.Volume 6776.
[23]M.Zimmermann and K.Dostert. A multi-path signal propagation model for the powerline channel in the high frequency range[C].in:Proc.3rd Int.Symp.Powerline Communications and its Applications,Lancaster,U.K.,1999,PP.45-51
[24]Manfred Zimmermann and Klaus Dostert. A multipath model for the
powerline channel[J]. IEEE Transactions, Volume 50, number 4, April 2002.
[25]Francis Berrysmith. A Multi-path Model for the Power Line Channel.,University of Auckland.
[26]SJ/T11138-1997.[S]
[27]易浩勇,汪晓岩,孙荣久等.中压配电网载波通信的多径反射模型研究[J].电力系统通信,2004年,1期.
[28]陈宗仕.电视信号在同轴电缆中的传输.[J].中国有线电视.2007.(21)
[29]张红 陈志国 杨家胜.有线电视宽带电缆接入系统(EoC)测试评估.[J].世界宽带网络.2009年8月71-75
[30]王正林.精通MATLAB科学计算.[M].北京：电子工业出版社,2007.ch10
[31]葛哲学.精通MATLAB.[M].北京：电子工业出版社.2008
[32]1stopt软件http://www.7d-soft.com
[33]郑君里,信号与系统.[M].北京高等教育出版社2005