CN1878109A - HFC network high-frequency broadband access technique - Google Patents
HFC network high-frequency broadband access technique Download PDFInfo
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- CN1878109A CN1878109A CN 200610090999 CN200610090999A CN1878109A CN 1878109 A CN1878109 A CN 1878109A CN 200610090999 CN200610090999 CN 200610090999 CN 200610090999 A CN200610090999 A CN 200610090999A CN 1878109 A CN1878109 A CN 1878109A
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Abstract
The invention discloses a high-frequency broad band switch-in system based on HFC network, which is characterized by the following: realizing broad band to switch from deme optical node to LAN through optical fiber Ethernet technology; utilizing 860MHz-1.4GHz frequency band of coaxial cable to transmit broad band data signal modulated by RF; realizing broad band network to switch in the wire TV user. The entire system is composed of gateway, net-bridge and terminal to provide over 200Mbps broad band for entire deme user under each HFC network optical node, which makes single user switch-in broad band reach more than 50Mbps. The system provides enough broad band resource for kinds of broad band interactive business, which doesn't influence normal transmission of present TV programs less than 860MHz.
Description
Technical field
The present invention relates to the access technology of broadband network in the field of network communication.
Background technology
Along with the development of network communications technology, for providing the interdynamic video entertainment service, the domestic consumer just progressively becomes a huge new industry by broadband networks.At present, the core net bandwidth resources are very abundant, and the deficiency of Access Network bandwidth becomes the main bottleneck that limits this industry development.
Hfc plant has very high transmission bandwidth, is best carrying platform in the existing various access networks.But because the restriction of prior art makes that the enormous bandwidth advantage of coaxial cable is not given full play to.
Comparative maturity is Cable Modem system in the existing HFC net broadband access technology.Cable Modem system is made of headend CMTS and user side Cable Modem.CMTS generally is placed on wired network sub-headend machine room, realizes the conversion of IP data and radiofrequency signal, and IP network interface and HFC are provided online down going channel radio frequency interface.Cable Modem places user house, demodulates the IP data from the radiofrequency signal that wire cable transmits, and exports to the network terminals such as computer, IP set-top box.
But there are following three aspect problems in actual applications in Cable Modem system:
1. network insertion bandwidth deficiency
The maximum bandwidth of supporting 51Mbps of the down going channel of each CMTS, data feedback channel is the bandwidth of 30Mbps to the maximum.Every CMTS equipment will provide access service for 2000-4000 user under 4-8 the optical node at least, on average arrives each user, has only the transmission rate of hundreds of K bit at most.
2. the network connective stability is poor
Cable Modem system descending channel stability is better, and up channel stability is poor.According to the DOCSIS standard, system uplink channel is operated in the low-frequency range of 5-42MHz (U.S. mark) or 5-65MHz (Europe superscript), and this frequency range is easy to be subjected to various interference of noise.Simultaneously, all noises of introducing at user side all can converge to the up input port of CMTS with upward signal, form the leak noise effect.Make the signal-to-noise ratio degradation of upward signal, user's online is easy to go offline.
3. network rebuilding quantities is big, and investment is high
Use Cable Modem system, must carry out bidirectional rebuilding to existing hfc plant earlier.Reforming content comprises equipment such as increasing backlight transmitter, backlight receiver, sign-changing amplifier.Simultaneously, for improving the signal quality of up channel, also need to change subscriber box and the relatively poor service cable of shielding.This makes the quantities of the network rebuilding and early investment very big, and the operation risk of operator is very high.
Owing to above reason, Cable Modem system is not also used at present at home widely.
Along with the development of network communications technology, very big variation has all taken place in hfc plant overall architecture and network transmission technology.At present, the cable network in most of area has all carried out the fiberize transformation, and optical fibre installation has arrived each residential quarter, and each sub-district optical node generally all can leave 4-6 root optical fiber interface, remove and be used to transmit outside the optical fiber of cable TV, also have optical fiber more than needed to can be used for the transmission broadband data.Utilize equipment such as present technology maturation, cheap Ethernet optical switch and optical transceiver, only need a monomode fiber that connects sub-headend machine room and wired optical node, just the two-way broadband data of 1000Mbps even 10Gbps can be received the optical node of sub-district.
Network insertion to the sub-district optical node from user family can utilize wired coaxial cable to realize.Coaxial cable has the above bandwidth of very high 1Ghz.At present, wired operator has only utilized the wherein following unidirectional TV programme of band transmissions of 860MHz, and the above frequency range of 860Mhz is not utilized, and this is a kind of huge waste to the coaxial cable frequency spectrum resource.Utilize the above high band transmission bi-directional data signal of 860Mhz, can provide very high network insertion bandwidth, can not influence the transmission of existing TV programme simultaneously for the user.
Summary of the invention
The present invention is intended to solve the problem of aspects such as Cable Modem grid access bandwidth is low, poor stability, network rebuilding cost height, and a kind of Wideband access technology that can make full use of the hfc plant bandwidth resources is provided.
A kind of hfc plant high-frequency broadband access technique, its system is made up of gateway, bridge and terminal: gateway is the high-frequency signal of 860MHz-1.4GHz frequency range with data signal modulation, and sends to bridge or terminal after the TV signal of the following frequency range of 860MHz is mixed; Bridge is connected across the amplifier both sides, guarantees that two-way high-frequency data signal is smoothly by unidirectional amplifier; Terminal is separated mixed signal, will send to communicating terminal behind the demodulated data signal; Data-signal is carried out transmitted in both directions, TV signal one-way transmission.
Data-signal uplink and downlink transmission channel adopts with the semiduplex communication mechanism of frequency, and the data-signal of uplink and downlink adopts QAM and OFDM modulation multiplex technology.
Realize the mutual conversion of intermediate frequency data modulation signal and 860MHz-1.4GHz high-frequency data modulation signal by frequency translation module, utilize the operating state of conversion of MAC bidirectional transmit-receive control signal control frequency modular converter medium frequency and power amplification circuit, realize the frequency inverted and the power amplification of two-way signaling.
The frequency translation module of local side is handled with local side MAC and QAM modulates shared same crystal oscillator signal; The frequency translation module of user side is handled with user side MAC and QAM modulates shared same crystal oscillator signal.
Compared with prior art, the invention has the beneficial effects as follows:
(1) the present invention has made full use of existing hfc plant bandwidth resources, has solved the problem of aspects such as CableModem grid access bandwidth is low, poor stability, network rebuilding cost height.
(2) because the up-downgoing passage all is operated in high band, solve the problem of low frequency noises, improved the user network quality of connection.
(3) owing to utilized the high band of 860MHz-1.4GHz, there is the above frequency spectrum resource of 500MHz to make full use of, can not be subjected to the restriction of Cable Modem 6MHz of system or 8MHz analog channel bandwidth, can provide the access bandwidth more than the 50Mbps at least for each inserts the user.
(4) adopted QAM and OFDM modulation multiplex technology, made whole connecting system have extremely strong anti-interference and very high receiving sensitivity.
Description of drawings
Fig. 1 is system's syndeton schematic diagram;
Fig. 2 is the gateway structural representation;
Fig. 3 is the bridge structural representation;
Fig. 4 is the terminal structure schematic diagram.
Embodiment
Now reaching embodiment in conjunction with the accompanying drawings is described in further detail the present invention.
With reference to figure 1, the structure of whole connecting system as shown in the figure.In the system, data-signal 102 is carried out transmitted in both directions, and TV signal 101 is carried out unidirectional downlink transfer, and data-signal 102 merges in coaxial cable with TV signal 101.
During downlink transfer, gateway 103 is modulated to the 860MHz-1.4GHz frequency range with data-signal 102, after TV signal 101 is mixed, sends to downstream bridge 104; Bridge 104 separates the mixed signal that gateway 103 transmits, and TV signal 101 is delivered to amplifier 105, mixes with data-signal 102 after amplifier 105 outputs again, sends to branch's adapter 106; Send terminal 108 again to, TV signal 101 is distributed to television set 111 the most at last, will distribute to computer 110 after data-signal 102 demodulation; Branch's adapter 106 back can also connect branch's adapter 107 as required, in like manner pass to terminal 109, and then distribute to computer 112 and television set 113.
Uplink, terminal 108 and terminal 109 are modulated to 860MHz-1.4GHz with data-signal 102, send to bridge 104 and gateway 103 by corresponding branch adapter again, and gateway 103 is again with after data-signal 102 demodulation, by upstream Interface, send to the data backbone network of front end.
With reference to Fig. 2, the structure of gateway 103 as shown in the figure.Every gateway provides one road gigabit Ethernet optical interface, four road rf input interfaces, four tunnel radio frequency output interface.The Ethernet optical interface of gateway connects the network equipment that is positioned at the sub-headend machine room by optical fiber; Four road rf input ports connect four road radio frequencies output of optical receiver respectively; The output of four road radio frequencies connects the cable distribution network of four direction respectively.Each optical node only needs a gateway device, and the network bandwidth more than the 200Mbps can be provided for the community user under this optical node.
Gateway 103 is installed in hfc plant optical node place, after downlink data signal 102 enters gateway by optical fiber, gateway is according to destination address, data are distributed to the corresponding a certain network port of four tunnel outputs, carry out processing 201 of MAC layer network and modulation 202, and the frequency inverted of data modulated signal is arrived in the 860MHz-1.4GHz frequency range.After the following TV signal of four road 860MHz of optical receiver output enters gateway, mix, export to the downstream cables transmission system by radio frequency interface with the data modulated signal of corresponding port.Up radiofrequency signal enters gateway by radio frequency interface, after down-conversion, demultiplexing, demodulation and mac-layer protocol conversion, is reduced to network data, and sends to core net by the uplink optical fiber interface.
With reference to figure 3, the structure of bridge 104 as shown in the figure.Bridge 104 is connected across the two ends of amplifier 105 in the cable distribution network, solves the two-way high-frequency data signal of 860MHz-1.4GHz and can't realize the transmitted in both directions of broadband network data by the problem of unidirectional amplifier.After the mixed signal 206 of gateway 103 outputs enters bridge 105, bridge 105 separates the TV signal below the 860MHz 101 with the downlink data signal 204 of 860MHz-1.4GHz, cable TV signal 101 is output to sends into bridge 104 after former amplifier 105 amplifies again, data-signal 204 processes lead directly to, amplify or mix with the TV signal 101 after the amplification regeneration back, export to the cable distribution network in downstream.The upward signal of terminal or downstream bridge output only comprises data-signal, through data-signal behind the bridge through straight-through, amplify or regeneration after, export to the gateway or the bridge equipment of upstream.
With reference to Fig. 4, the structure of terminal 108 as shown in the figure.Terminal equipment is placed on the indoor use of user usually.The mixed signal 206 of gateway 103 or bridge 104 outputs is divided into 860MHz following TV signal 101 and downlink data signal 102 after entering terminal 108.TV signal 101 is directly exported to equipment such as television set 111 or digital TV set-top box.Data-signal 102 is sent into computer 110 or network-termination devices such as IP set-top box, IP phone machine by Ethernet interface or USB interface through last/down-conversion 402, QAM/OFDM demodulation 403, MAC layer network after handling 404, realize user's online, video request program, and business such as calling IP phone.
The modulation multiplex of data-signal
System utilizes Orthodoxy Frequency Division Multiplex (OFDM) and quadrature amplitude modulation (qam) technology to realize the modulation of bi-directional data signal and multiplexing.
The quadrature amplitude modulation (qam) technology that adopts each subchannel realizes the modulation to the two-way broadband data.System supports multiple modulation systems such as 256QAM, 64QAM, 16QAM, and can freely select according to concrete channel transmission quality.Adopt the QAM modulation technique to provide very high data transmission rate and anti-interference for whole system.
Adopt the OFDM multiplexing technique that the data carrier of a high speed is divided into the subcarrier of several low speed, send these subcarriers then concurrently.The channel spacing of OFDM modulation technique sub-carriers is very near, can use frequency spectrum effectively.Be quadrature between each subcarrier, can guarantee can not interfere with each other between the subcarrier.Adopt the OFDM multiplex technique, can guarantee that broadband access system has very strong anti-interference, solves the narrow-band impulse interference problem very effectively.By combined coding, even some subchannels are subjected to serious disturbance, can also transmit by other information, whole network channel still can operate as normal.
Working frequency range is selected
At present, 5-65MHz is used to transmit Cable Modem system uplink data in the cable TV network, and 87-860MHz is used for the TV transmission program, and the above frequency range of 860MHz is not utilized.
Radiofrequency signal can produce decay in wired transmission over coaxial cable, and decay intensity is directly proportional with the square root of signal frequency, and signal frequency is high more, and it is big more to decay.Simultaneously, the various passive devices in the cable network also can produce decay to radiofrequency signal.According to actual test shows, passive devices such as branch distributor are less to the radiofrequency signal attenuation ratio of frequency below 1.4GHz, and have higher consistency.Because adopted the modulation multiplex mode of QAM and OFDM, system has very high receiving sensitivity.Because system has the higher signal transmitting power, can solve fully simultaneously because the bigger problem of the higher decay that brings of message transmission frequency.Working frequency range is chosen in high band more than the 860MHz, can clash, also avoided being operated in simultaneously the noise jamming problem that low-frequency range is easy to introduce with the transmission of existing TV programme.
The above execution mode only is the preferred embodiments of the present invention; the invention is not restricted to the foregoing description; for persons skilled in the art; the any conspicuous change of under the prerequisite that does not deviate from the principle of the invention it being done all belongs to the protection range of design of the present invention and claims.
Claims (5)
1. a hfc plant high-frequency broadband access technique is made up of gateway, bridge and terminal, it is characterized in that:
Gateway is the high-frequency signal of 860MHz-1.4GHz frequency range with data signal modulation, and sends to bridge or terminal after the TV signal of the following frequency range of 860MHz is mixed;
Bridge is connected across the amplifier both sides, guarantees that two-way high-frequency data signal is smoothly by unidirectional amplifier;
Terminal is separated mixed signal, will send to communicating terminal behind the demodulated data signal;
Data-signal is carried out transmitted in both directions, TV signal one-way transmission.
2. access technology as claimed in claim 1 is characterized in that: data-signal uplink and downlink transmission channel adopts with the semiduplex communication mechanism of frequency.
3. access technology as claimed in claim 1 or 2 is characterized in that: the data-signal of uplink and downlink adopts QAM and OFDM modulation multiplex technology.
4. access technology as claimed in claim 1, it is characterized in that: realize the mutual conversion of intermediate frequency data modulation signal and 860MHz-1.4GHz high-frequency data modulation signal by frequency translation module, utilize the operating state of conversion of MAC bidirectional transmit-receive control signal control frequency modular converter medium frequency and power amplification circuit, realize the frequency inverted and the power amplification of two-way signaling.
5. as claim 1 or 4 described access technologies, it is characterized in that: the frequency translation module of local side, modulate shared same crystal oscillator signal with local side MAC processing and QAM; The frequency translation module of user side is handled with user side MAC and QAM modulates shared same crystal oscillator signal.
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| CN 200610090999 CN1878109A (en) | 2006-07-06 | 2006-07-06 | HFC network high-frequency broadband access technique |
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| CN 200610090999 CN1878109A (en) | 2006-07-06 | 2006-07-06 | HFC network high-frequency broadband access technique |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012041028A1 (en) * | 2010-09-30 | 2012-04-05 | 深圳市同洲电子股份有限公司 | Method, correlative equipment and system for bidirectional hybrid fiber-coaxial (hfc) network based video conference |
| CN103067688A (en) * | 2012-12-20 | 2013-04-24 | 西湖电子集团有限公司 | Method based on hybrid networks of internet protocol (IP) and hybrid fiber coaxial (HFC) for achieving video conference |
| CN103518332A (en) * | 2011-05-12 | 2014-01-15 | 西门子公司 | Subsea data communication system and method |
-
2006
- 2006-07-06 CN CN 200610090999 patent/CN1878109A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012041028A1 (en) * | 2010-09-30 | 2012-04-05 | 深圳市同洲电子股份有限公司 | Method, correlative equipment and system for bidirectional hybrid fiber-coaxial (hfc) network based video conference |
| CN103518332A (en) * | 2011-05-12 | 2014-01-15 | 西门子公司 | Subsea data communication system and method |
| US9049014B2 (en) | 2011-05-12 | 2015-06-02 | Siemens Aktiengesellschaft | Subsea data communication system and method |
| CN103518332B (en) * | 2011-05-12 | 2016-12-28 | 西门子公司 | Underwater data communications system and method |
| CN103067688A (en) * | 2012-12-20 | 2013-04-24 | 西湖电子集团有限公司 | Method based on hybrid networks of internet protocol (IP) and hybrid fiber coaxial (HFC) for achieving video conference |
| CN103067688B (en) * | 2012-12-20 | 2016-07-13 | 西湖电子集团有限公司 | Based on the method that IP and HFC hybrid network realizes video conference |
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Owner name: XINHE HOLDING LIMITED Free format text: FORMER OWNER: BEIJING GATEWAY SCIENCE AND TECHNOLOGY CO., LTD. Effective date: 20080229 Owner name: BEIJING GATEWAY SCIENCE AND TECHNOLOGY CO., LTD. Free format text: FORMER OWNER: WEI QIANG Effective date: 20080229 |
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Effective date of registration: 20080229 Address after: Vitoria, Republic of Seychelles Applicant after: Xinhe Holding Corp. Address before: Room 21-4-203204, West Lane, calling house, Beijing, Chaoyang District: 100026 Applicant before: Beijing Huajin Science & Technology Co.,Ltd. Effective date of registration: 20080229 Address after: Room 21-4-203204, West Lane, calling house, Beijing, Chaoyang District: 100026 Applicant after: Beijing Huajin Science & Technology Co.,Ltd. Address before: 11-1-218, 178 Beiyuan Road, Beijing, Chaoyang District, China: 100101 Applicant before: Wei Qiang |
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