CN1189028A - Network apparatus and method to provide compressed digital video over mini-fiber nodes - Google Patents
Network apparatus and method to provide compressed digital video over mini-fiber nodes Download PDFInfo
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- CN1189028A CN1189028A CN97122472A CN97122472A CN1189028A CN 1189028 A CN1189028 A CN 1189028A CN 97122472 A CN97122472 A CN 97122472A CN 97122472 A CN97122472 A CN 97122472A CN 1189028 A CN1189028 A CN 1189028A
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Abstract
A communication network and method is provided to communicate between a central office/head end and a plurality of end-units (EUs).The intermediate node is also associated with each of the mini-fiber nodes such that an analog broadcast service may be sent over the first transmission medium to each of the mini-fiber nodes. Further, switched digital services and digital broadcast services are also sent over the second transmission mediums to each of the mini-fiber nodes. The mini-fiber nodes combine the signals and send the combined signals to a corresponding subset of EUs.
Description
The present invention relates to provides Video service to hybrid fiber/coaxial (HFC) network, particularly compressed and multiplexed digital video signal is offered miniature fiber node (mFN) FHC network.
Traditional CATV system uses by 55MHz to 350MHz, and (central office) provides downlink broadcast information to terminal unit (EU) to the analog broadcast signal of 550MHz even 750MHz from the central office as multichannel CATV channel (AM-VSB).The channel capacity that the cable network operator encourages to increase its cable system is used the supplementary service of increasing income is provided, as quality improve watch channel and by the channel of watching of pay per channel.But coaxial cable or hybrid fiber/cable (HFC) system upgrade of routine are needed to redesign whole cable machineries to 750MHz (or from 350MHz to 550MHz), comprise that at least changing amplifier (upgrading) reaches relevant amplifier at interval.In addition, the network operator of a lot of conventional systems also wants to provide broadcast figure signal and analog signal on single transmission line.But this is difficult to, because the impulsive noise of analog signal can cause the mistake of digital signal.As see " impulsive noise that amplitude limit causes and to the influence of the error performance of AM-VSB/QAM mixing lightwave system " at the 866-868 page or leaf of PTL94 7 monthly magazines such as LU of drawing for reference here.The expense of this cable machinery upgrading why explained the U.S. not most conventional CATV device upgrades to 750MHz.
Its subject content provides a kind of adaptation that the mFN of hfc plant is upgraded here by the U.S. Patent Application Serial Number 08/526,736 of application in September nineteen ninety-five of reference.Original existing hfc plant provides by first path of central office to EU.At the mFN-HFC network that draws, the received signal of the mFN that is come by central office (central office) is separated from original existing hfc plant through second path and is sent to EU.MFN can receive the next upward signal of EU and be transmitted back to the central office in second path in addition.Chang Gui general knowledge in addition, illustrative in " design of digital professional retrieval system " of the 269-277 page or leaf in the ITE Institute of Telecommunication Engineers on January 10th, 1996 as people such as Stoneback, its subject content advises that here by reference every hertz of constant power is as every hertz of power configuration of recommending when transmission comprises the different modulating mode of different bandwidth.But, because do not provide performance of services to require to dispose every hertz of power with each to cause the problem that comprises that the mHN-FHC network is invalid according to what provide by every kind of signal type.
Therefore need a kind of effective cost effective device and method to offer the broadcast video channel and improve the power configuration of mFN-HFC network with existing C ATV system upgrade so that with the digital video (CDV) of compression.
A communication network is provided, comprises central office and a plurality of first transmission medium, be used at least one with a plurality of terminal units of central office is connected.The central office sends first broadcast singal along sending by the distributing signal that terminal received of at least one appointment one of in a plurality of first transmission mediums along in a plurality of first transmission mediums each.
Another kind of communication network is provided, and it comprises one first transmission medium and a plurality of second transmission medium, and it separates with first transmission medium, is connected to the central office.Network also comprises a plurality of intermediate medium nodes and a plurality of passive transmission medium.The central office sends first broadcasting service and send second broadcasting service on a plurality of second transmission medium on first transmission medium.In a plurality of intermediate medium nodes each is connected on one independent in a plurality of second transmission mediums and is connected on first transmission medium so that first broadcasting service and second broadcasting service are combined.In a plurality of passive transmission mediums each all is connected with one of intermediate medium node that transmits composite service, and composite service is received by corresponding sub-device in a plurality of terminal units.
Another kind of communication network also is provided, comprises the central office, be used for transmission medium and output control device that the central office is connected with a plurality of terminal units.The central office along transmission medium send a plurality of digital services and output control device according to the analog submodule carrier wave numeral service signal that transmits on the every channel power control transmission medium that require to determine by the bit error rate performance that digital service is provided.
The HFC intercommunication system (network) that uses miniature fiber node (mFN) and central office interface unit broadcast singal on the mFN path is provided.Use identical video format to use the technology of development as DBS (DBS) signal mFN-HFC network.Obvious available extended formatting.This realization causes cheap connectivity in addition, can provide compressed digital video signals and broadcast video business in the mFN-HFC system.
And then, requiring to dispose every hertz of power of transmission signals according to the error rate of terminal unit, the mFN-HFC network can transmission of digital broadcast video business (being CDV) and transformation service.The error rate of terminal unit (BER) requires at least by the business that provides, modulation system and error correcting technique, or what also has, and other is determined.
In addition, the mF-HFC network as being realized, the upgrading of the hfc plant of routine can not needed to redesign existing cable unit or upset the CATV system that existing service surpasses current state-of-art owing to it can provide bi-directional capability and additional multichannel broadcast figure vision signal simultaneously.
The detailed description of being carried out in conjunction with the accompanying drawings to preferred implementation of the present invention, of the present invention other purpose, advantage and prominent features will be more obvious.
Will be with reference to following description of drawings the present invention, wherein identical reference number is represented components identical, wherein:
Fig. 1 is that expression uses mFN to transmit the hfc plant figure of CDV signal according to a preferred embodiment of the present invention;
Fig. 2 is illustrated in service bandwidth distribution diagram in the mFN-HFC network of Fig. 1;
Fig. 3 is the figure of a part of the another kind of structure of expression central office;
Fig. 4 is the figure of a part of another structure of expression central office;
Fig. 5 is the figure of the RF signal of expression drive laser;
Fig. 6 is the figure that expression is drawn as BER the function of RF drive level; With
Fig. 7 is the general remark of Fig. 1.
Discussing as shown in Figure 1 according to preferred implementation of the present invention uses miniature fiber node (mFN) to transmit hybrid fiber/coaxial (HFC) bidirectional communication network 100 of compressed digital video signals (CDV).Basic mFN-HFC structure at first is described, introducing then provides broadcast singal.We introduce equipment and the method that is used for increasing the optical link capacity at last.
The general figure of Fig. 7 presentation graphs 1 execution mode.Transmitter 142 is sending analog broadcast signal to Fiber Node (FN) 120 on the optical fiber 101.From FN120, a plurality of coaxial cables 125 are connected to each amplifier/mFN module 160 with separator 124
1-160
nOn.For simplifying an amplifier/mFN module 160 only is shown
1-160
nBe connected on each coaxial cable, can be but can be understood as with a plurality of amplifiers/mFN module 160
1-160
nBe connected on each coaxial cable 125.Central office 110 is from each central office interface unit (central office IU) 150 in addition
1, 150
2With 150
nRespectively along optical fiber 102
1, 102
2And 102
nOutput digital broadcasting vision signal.Each central office IU150
1-150
nCan be connected to one or more amplifier/mFN160
1-160
nOn.
Also each central office interface unit 150 of design that can be suitable
1-150
nMake it also can be along each optical fiber 102
1-102
nTransmit the digital translation service signal.Further optical fiber is connected to amplifier/mFN module 160
1-160
nOn.So amplifier/mFN module 160
1-160
nEach receives along the analog broadcast signal of optical fiber 101 transmission and is also received in optical fiber 102
1-102
nThe digital broadcast signal of last transmission.Equally amplifier/mFN module 160
1-160
nEach be connected to corresponding coaxial cable 180
1-180
nAnd along each root cable 180-180
nBe connected on the sub-device of relevant terminal unit (EU).Each central office interface unit 150
1-150
nCan receive the up inverse signal that is sent to central office 110 from EU, not draw among Fig. 7.
When in the EU184 of cable 180 specific one, as 184
x, when wanting conversion (or distribution) professional, central office IU150
nExport corresponding transformation service signal along optical fiber 102
nTo amplifier/mFN module 160
nAnd finally reach cable 180
nSpecific EU184 just receives transformation service, the most handy encrypted form.
In brief, the present invention makes EU, as specific EU184
xReception is from the analog broadcast signal of transmitter 142 with from central office interface unit 150
1-150
nIn one of the digital signal that comprises broadcast singal and transformation service signal of coming.In each amplifier/mFN module with these signals suitable combine and on the sub-device that is sent to physics and unit, logically connected terminal on each cable.In addition, have only and need the particular terminal of transformation service unit to receive and this transformation service signal of suitably decoding.
As shown in Figure 1, central office (central office) 110 is connected to the remote signaling allocation units through optical fiber 101, hereinafter it is called FN120.As selection, optical fiber 101 also can be a coaxial cable.Analog broadcasting information is transmitted in central office 110, as the many CATV channel (AM-VSB) with high-quality laser transmitter 142 and optical fiber 101.In mFN-HFC network 100, by transmitter 142 the AM-VSB signal broadcasting to a plurality of, about 1,000 EU184
1-184
1000(not shown) (after this EU that is connected on the central office 110 being called EU184) broadcast message is launched machine 142 and launches on analog carrier as analog information.
At FN120, light signal and broadcast message are received machine 122 and receive and convert to the signal of telecommunication.FN120 is through a plurality of coaxial cables 125 of separator 124 services.
As shown in Figure 2, the downlink broadcast information on the coaxial cable 125 comprises that analog signal is to provide CATV business (AM-VSB).In demonstration system, simulation CATV business occupies the bandwidth from 55MHz to 550MHz.Coaxial cable 125 is connected to corresponding a plurality of amplifier/mFN module 160 with FN120
1-160
nOn.Amplifier/mFN module 160
1Expression amplifier/mFN module 160
1-160
nOne of typical structure.Amplifier/mFN module 160
2-160
nSimilar, therefore for clarity sake do not draw among Fig. 1.
From amplifier/mFN module 160
1, coaxial cable 180
1Distributing signal is received signal to the sub-device of the physical connection of Eu184 and from the sub-device of the physical connection of EU184.Each EU184 comprises network interface unit 190, be connected to it on the telephone unit 192 so long, can comprise a video unit of top setting box (set-topbox) 194, and a modulator-demodulator or personal computing system 196.Fig. 1 demonstration terminal unit such as EU184 that draw
1
As shown in Figure 1, amplifier/mFN module 160
1Connect mFN166
1And unidirectional amplifier 162
1, by duplexer 164
1Be connected on the sub-device of about 50 EU184, EU184 wherein only draws
1And EU184
2It is each amplifier/mFN module 160
1-160
nRelevant with the sub-device of EU184.MFN166
1Comprise optical receiver 168
1, laser transmitter 167
1, and duplexer 169
1Optical fiber 102
1With central office IU150
1In transmitter 148
1Be connected to mFN166
1On.Similarly, optical fiber 103
1Central office IU150
1Receiver 151
1Be connected to mFN166
1On.The scheme of the single fiber that substitutes can be at central office IU150
1-150
nAnd amplifier/mFN module 160
1-160
nBetween realize with light transmitter-receiver or optical coupler.Also can use light separator and combiner, adopt wavelength division multiplexing (WDM) probably many mFN160
1-160
nBe connected on the central office 110 (as a pair of transmitter 148
1-148
nWith receiver 151
1-151
n) to reduce the optical fiber that needs.
Duplexer 164
1Will be from FN120 (through amplifier 162
1) and mFN166
1The signal combination that sends is delivered to coaxial cable 180
1On.Duplexer 164
1Also from being connected to amplifier/mFN module 160
1The upward signal that comes of the sub-device of EU184 pass on the central office 110.Can dynamically arrange duplexer 164
1--164
nBut the feasible dynamic assignment of intersection central office interface unit 150
1-150
nBe delivered to the professional of EU184 and with the bandwidth of the business of transmitter 142 transmission.Can will distribute to the bandwidth constraints of transmitter 142 at amplifier 162
1--162
nAbility within.
As shown in Figure 2, central office 110 sends bandwidth from the descending analog broadcast signal of 55MHz to 550MHz and through receiver 122, separator 124, coaxial cable 125, amplifier 162 on optical fiber 101
1-162
n, duplexer 164
1-164
nWith coaxial cable 180
1--180
nTo EU184.The digital signal that last these analog signals can simulated on the subcarrier replaces.For example, when using HDTV (high definition video), the cable network operator uses the HDTV channel and replaces some AM-VSB channel.
Amplifier/mFN module 160
1-160
nAlong coaxial cable 125 mFN166
1-166
nBe placed on contiguous each distribution amplifier 162
1-162
nThe place.Duplexer 164
1By coaxial cable 180
1Amplifier 162
1And mFN166
1Link on the sub-device of EU184.Therefore supplementary service is merged into and does not influence downlink broadcast CATV business in the mFN-HFC network 100.
At U.S. Patent Application Serial Number No.08/526, described on the mFN-HFC network in 736 transformation service is provided.Available central office 110 is as central office IU150
1At optical fiber 102
1, 103
1, mFN166
1, duplexer 164
1, coaxial cable 180
1Go up and in frequency band 580MHz to 1GHz, transformation service is delivered on the sub-device of EU184.Can be at coaxial cable 180
1Bandwidth within and give outside the broadcasting service bandwidth that transmits on transmitter 142 and the optical fiber 101 and come the dynamic assignment transformation service.As shown in Figure 2, some are professional as phone, visual telephone, and fax, the enhancing business (EPPV) of every viewing channel payment etc. is pressed in data service, can use the frequency band of 580MHz to 1GHz.The 5-40MHz bandwidth can be used for upward signal in addition, to keep the compatibility with conventional hfc plant.
Transmitter 148
1-148
nWith receiver 151
1-151
nUse module 146
1-146
nInsert transformation service (below be also referred to as distribution service) to be provided at central office 110.Service supplier can pass through module 146
1-146
nReceive on the central office 110.Transmitter 148
1-148
n(for example, from 580MHz to 1GHz) is at optical fiber 102 outside the bandwidth of transmitter 142
1-102
nGo up distribution service is delivered to mFN166
1-166
nOn.Further use duplexer 164
1-164
nWith coaxial cable 180
1--180
nTo broadcast or distribution service is sent on the EU184.Like this, uplink and downlink distribution service just is being higher than with y axis amplifier y 162
1--162
nThe system bandwidth of bandwidth constraints.Employing is higher than with y axis amplifier y 162
1--162
nThe bandwidth of bandwidth constraints is with amplifier 162
1--162
nOffer the professional unaffected of EU184.Increased in addition the total bandwidth available of mFN-HFC network 100.
Though transmitter 142 can be at the hfc plant broadcast singal to whole EU184, also the available transmission machine 148
1-148
nAt mFN166
1-166
nLast transmission broadcast singal.Transmitter 148
1-148
nThe ability that transmission CDV signal is arranged, but transmitter 148
1-148
nMay not meet the desired strict specification requirement of transportation simulator AM-VSB signal.
Provide CDV decoder module (not shown) to provide to comprise broadcasting CDV the broadcast figure business of signal with the single broadcast module 144 in the central office 110 and at each EU184.The CDV decoder module can be merged into the separate unit that is independent of video unit or be incorporated within the video unit 194.Broadcast module 144 is by corresponding combiner 147
1-147
nBe connected to transmitter 148
1-148
nEach on.This structure allows central office 110 at optical fiber 102
1-102
nUpward the broadcast figure business is provided to and is connected amplifier/mFN module 160
1-160
nAll EU184 on.
MFN166
1-166
nBe the simulated light transmitter-receiver and transmit digital information with the analog submodule carrier wave.Amplifier/mFN module 160
1-160
nAmplifier 162
1-162
nMaintain coaxial cable 125 and 180
1--180
nThe signal level of last requirement.Therefore along cable 180
1-180
nFrom amplifier/mFN module 160
1-160
nEU184 coaxial cable element to each connection is passive.Comprise duplexer 164
1-164
nPassive transmission medium available bandwidth be the contrast of 1GHz and active coaxial system, the latter is limited in 750MHz by the two-way and unidirectional amplifier of routine.As shown in Figure 2, the mFN-HFC network 100 of Fig. 1 helps using the bandwidth from 55MHz to 1GHz on the passive coaxial cable element.In addition, because be passive, at mFN166 to the connection of family
1-166
nAnd family lays suitable filters can distribute this bandwidth flexibly between uplink and downlink.
As mentioned above, in one embodiment, mFN166
1-166
nOn the analog submodule carrier wave, transmit digital information.Because these signals do not need to simulate the desired high-performance of AM-VSB, transmitter 148
1-148
n, receiver 151
1-151
n, receiver 168
1-168
nWith emission receipts machine 167
1-167
nCan use the cheap laser and the electronic device of low-power consumption.In addition, because central office interface unit 150
1-150
nDo not transmit the VSB signal of being strict with the SNR and the linearity, do not need high performance laser 142.Also have, the modularity of mFN-HFC network 100 provides any existing coaxial cable system connectivity easily.But, when transmitting CDV and various types of business simultaneously, distribute power to give the prior art of transmission signals just not competent.
According to an execution mode, by broadcast module 144 can provide up to as 70 tunnel broadcast figure video traffic.As shown in Figure 1, central office 110 uses the digital video (CDV) of compression that the digital broadcasting video is sent to EU184.The CDV technology in the mFN-HFC network 100 of being combined in that a kind of energy is suitable has been developed and has been used for DBS (DBS) transmission.Therefore, the people of an ordinary skill can understand that how revising DBS CDV technology comes encode video information to transmit at mFN-HFC network 100 usefulness analog submodule carrier waves as digital information.With video compression standard such as MPEG video compression standard, can compressed video signal, as, to the bit rate that on average is about 4Mbps.Can use error correction coding such as Luo Meng of Ruide-institute and convolution error correcting code in addition.In one execution mode, error correction coding makes needs the bit rate of transmission to double, but signal to noise ratio (snr) requires to have reduced.Use the DBS technology recently to transmit CDV with the noise that is low to moderate 6dB.So transmitter 148
1-148
nPerformance comprise that for transmission broadcast figure business broadcast figure CDV signal is enough.Broadcast module 144 is through combiner 147
1-147
nThe CDV signal is offered transmitter 148
1-148
n
Therefore mFN-HFC network 100 shown in Figure 1 110 offers a plurality of EU184 broadcasting analog service, distribute digital business and broadcast figure business from the central office.Provide the broadcasting analog service and with transmitter 148 with transmitter 142
1-148
nDigital service (two kinds of switch/distribution service and broadcasting services) is provided.In brief, each central office interface unit 150
1-150
nBe included in optical fiber 102
1-102
nOne of go up distribution service and broadcast traffic transmissions to the amplifier/mFN module 160 relevant with the sub-device of EU184
1-160
nOne of transmitter 148
1-148
nIn addition, each central office interface unit 150
1-150
nCan give different optical fiber 102
1-102
n, 103
1-103
n, different amplifier/mFN module 160
1-160
nOr one group of amplifier/mFN module 160
1-160
nService.Equally, each central office interface unit 150
1-150
nCan be corresponding to one group of optical fiber 102
1-102
n, 103
1-103
n
The RF spectrum that is transferred to the signal of EU184 by central office 110 can be distributed with respect to business that EU184 was scheduled to or dynamic requirements.Since construct mFN-HFC network 100 to such an extent that provide digital broadcasting service to add the analog broadcasting business, can be RF spectrum in simulating transmitting machine 142 and central office interface unit 150
1-150
nIn transmitter 148
1-148
nBetween divide the requirement be equipped with more near EU184.The desired broadcasting service of EU184 can comprise basic video traffic, and radio traffic is with the extra charge channel service or the extra channel of the forms of broadcasting transmission of pressing viewing channel charge (PPV).About PPV or additional payment channel radio digital service, each selects professional terminal unit preferably to equip with decoding device.
The digital distribution business can comprise telecommunications, multimedia, transfer of data, sound and visual telephone and internet service.
With broadcasting service contrast, the distribute digital business that comprises the distribute digital video is to require or confirm to be transferred on the EU184 on the special relevant EU184 of a calling in beginning one.Distribution service just only is transferred to amplifier/mFN module 160
1-160
nOn.When receiving the RF spectrum of transmission, each EU184 will carry the part decoding of that digital distribution signal of wanting to select professional EU184.Promptly have only among the EU184 and to require or that distribution service of just may " decoding " transmitting of assignment of allocation business.
Fig. 3 represents another execution mode, wherein the dynamic distribution of the EU184 in the mFN-HFC network is advanced in the broadcasting group.The spacing of broadcasting group can be low to moderate with physical connection to mFN such as mFN166
1-166
nThe number of EU184 identical.Because mFN166
1-166
nIn each is very relevant with FN120 in mFN-HFC network 100, from central office interface unit 150
1-150
nThe gap ratio FN120 of broadcasting group big.Each EU184 of broadcasting group receives identical digital broadcasting service.Relevant with each broadcasting group one of in the CDV channel selector 310.Broadcast figure channel waiting for transmission is by selected one of in the CDV channel selector 310 relevant with that broadcasting group.As shown in Figure 1, a plurality of CDV channel selector 310 are arranged in the central office 110.But each in the CDV channel selector 310 can be to a plurality of broadcasting groups or 110 services of a plurality of central office.CDV channel selector 310 can be positioned at central office 110 or away from the position of central office 110 in addition.Central office 110 allows mFN-HFC network operation person to use the demographic or geo-location parameter of predetermined EU184 to construct the broadcasting group.
Come video signal digitization and compression with the CDV encoder.The CDV encoder preferably is positioned at video source 320 places, so that do not need each is used each this channel of broadcasting group coding of same channel.Alternatively, can be placed on the CDV encoder in the channel selector 310.Use RF modulator-demodulator (not shown) that the CDV signal is put on the analog submodule carrier wave, frequency of utilization transducer (not shown) is transformed into suitable broadcasting frequency to these subcarriers.Can be placed on video source 320 to the RF modulator-demodulator, channel selector 310 or be shown in a plurality of broadcast module 144 places of Fig. 3.Can be placed on channel selector 310 or broadcast module 144 places to frequency converter.Can be channel selector 310 and video source 320 centre offices 110 places, though they do not need to be placed on the there.Can be distributed in many positions to video source 320.
Central office interface unit 150 in broadcast module 144 and central office 110
1-150
nA but the middle switching device 305 dynamic assignment broadcasting groups of replenishing.As shown in Figure 1 each central office interface unit 150
1-150
nThrough optical fiber 102
1-102
nPhysical connection is to relevant amplifier/mFN module 160
1-160
nOn.Though amplifier/mFN module 160
1-160
nOne of in, central office interface unit 150
1-150
nIn each by physical connection to the sub-device of EU184.It is each amplifier/mFN module 160
1-160 is relevant with the sub-device of its oneself EU184.Even the sub-device of the EU184 that shares common interest is organized together have been moved when the geographical line of demarcation between the neighbours.Say Spanish neighbours if expand one, a plurality of central office interface unit is added in a relevant central office and comprises in the broadcasting group at Spanish station.
Therefore the broadcasting group can be a selection of the sub-device of the requirement EU184 that can be integrated into the digital video channel in given a group, for example, and at 50 transmission channels.Fig. 3 shows a plurality of broadcast module 144.If all central office interface unit 150 that draws
1-150
nBe connected on one of broadcast module 144 with switching device 305, the broadcast figure business that provides will be similar with Fig. 1.In addition, the digital video channel that is transferred to the broadcasting group just can dynamically change with the selection of the sub-device of EU184 in the broadcasting group by the work of channel selector 310.
In other words, if a community that withdraws from is contiguous dwelling house community, available channel selector 310 is distributed to separately broadcasting group with financial news network and travelling channel rather than children's video channel.EU184 also receives the analog broadcasting business from analog broadcasting transmitter 142.
With oneself relevant modulation system and the relevant complexity of transmitting RF spectrum of error correcting technique while transmission of digital distribution service on single medium with the digital broadcasting service increase.The optical property that inserts the various signals that transmit on the big available bandwidth of a mFN-HFC system at mFN requires the distribution of channel power to the improvement of transmission signals bandwidth.The uplink and downlink channel that the suitable distribution of every hertz of power allows the cable operator effectively to utilize the mFN-HFC network to provide provide new business (that is, and phone, internet service, etc.).Therefore, the distribution of every hertz of power preferably is provided according to the business that provides by the mFN-HFC network.(when channel width is known, can calculate every hertz power from RF channel light modulation depth (0MD).) in addition, when the business that requires can dynamically be distributed, but every hertz of power of corresponding modification.
Fig. 4 represents that every type the business that an execution mode wherein provides has relevant attenuating device 407,408,409 in the RF spectrum by central office IU450 transmission.Central office IU450 and central office interface unit 150
1-150
nSimilar, therefore, after this central office IU450 and central office interface unit 150 only are discussed
1-150
nBetween difference.The RF spectrum of central office IU450 transmission is received by the subset of EU184.As shown in Figure 4, broadcast module 144 is connected on the attenuator 407.Provide the modulator-demodulator 146 of distribution service to be connected on the attenuator 148 and provide typical following professional typical following professional modulator-demodulator 416 to be connected on the attenuator 409.The RF spectrum signal of RF power to being transmitted by central office IU450 that is provided by relevant service supplier independently is provided each attenuator.
The BER performance requirement of the business that attenuator 407,408 and 409 provides according to central office IU450 is provided with every hertz power (PPH) or every channel power.Show that as Fig. 4 each attenuator can independently be controlled or control by an attenuator control device 415.In addition, optionally attenuator 407,408 and 409 is incorporated in broadcast module 144 respectively, in module 146 and the following business module 416, or in other relevant equipment.In other words, attenuator 407 can be the part of broadcast module 144.
The business on the EU184 of being provided to comprise different modulation classifications (as, Quadrature Phase Shift Keying and 64 quadrature amplitude modulation).Transmission broadcasting or distribute digital modulation format professional as digital video traffic or telephone service is known by the people that those are skilled in technique.In addition, the business that offers EU184 can comprise different error correcting techniques.Error correcting technique brings additional expense and signal propagation delay.For example, visual telephone can not hold very big time-delay therefore must be in conjunction with less error correcting technique.On the other hand, broadcast video is to delaying time insensitive so can be in conjunction with because signal processing is introduced the error correcting technique of time-delay.
Known as the people of those knacks, the business that is delivered to EU184 has different requirements.The predicate of available at least time-delay tolerance and fault tolerance illustrates these requirements.For example, transmission of music is good at tolerating time-delay but is can't stand very much mistake.On the contrary, the transmission voice services can be tolerated wrong but can't stand time-delay.
Therefore, BER performance setting as requested offers the PPH of transmission RF spectrum of business of the sub-device of EU184, can improve receiving total professional quality.Because the influence of modulation technique improves gross mass, error correcting technique and the professional tolerance of reception are combined in the BER performance requirement.
Fig. 5 represents the experimental data of 300MHZ to the 900MHz signal, comprises broadcast figure video traffic 510, telephone service 520 and data transmission service 530.The 16DBS from drawing CDV signal 511 with Quadrature Phase Shift Keying (QPSK) coding transmits the broadcast figure video traffic, transmits 5 video channels with every 40-MbpsQPSK channel.Separate the QPSK channel with 30MHz, so each video channel needs and the identical bandwidth of use AM-VSB, but good image quality is only needed the SNR of about 6dB.
Proved that non-cooling, the laser of non-isolation can transmit two data channels and surpass 70 CDV channels.In experiment, obtain the CDV signal and frequency displacement to 320-800MHz scope is moved from commercial DBS system.Use simple on-off keying and envelope error detection to come the channel of authentication data transport service 530 at 880MHz transmission 20Mbps.Transmission 2-Mbps QPSK channel proves and can transmit telephone signal.Current, existing telephone signal time division multiplexing to the business equipment of 2-Mbps QPSK channel that comes from many families can be used.
As shown in Figure 5, the RF spectrum of transmission signals explanation telephone service 520 is to be transmitted than broadcast figure video (CDV) professional 510 high about 8dB power.In addition, data transmission service 530 is transmitted than the about 16dB of the professional height of CDV.So the power level of three types of signals is minimum RF to the acceptable performance of all signals of balance to be driven is consistent.
Fig. 6 is the figure that the BER of expression data channel is drawn as the function of RF drive level.There is visible mistake to think unacceptable if also monitor image quality.Mistake shows as " the square state " in the image or resembles the image that freezes.Fetch data room temperature (25 ℃) and 85 ℃.No matter from 25 ℃ to 85 ℃ 60 ℃ temperature change, RF drive incoming level from approximately-8dB BER to the 20dB scope of-28dB good (keeps below 10
-9).Image quality in this scope also is good.Mistake when hanging down drive level is because the SNR relative brightness noise (RIN) of difference is significant noise source.Mistake when high drive level is that it produces impulsive noise because laser is lower than threshold drive.
Beginning amplitude limit (when laser is lower than threshold drive) depends on the total RF that is added on the laser and drives.If signal has equal PPH, take place in the time of then can hanging down at the power of 20Mbps data channel owing to the mistake of amplitude limit.The SNR of one special channel depends on the PPH of this channel when hanging down drive level.Because because the mistake of low SNR occurs under the identical minimum signal level, when causing that because of amplitude limit wrong maximum signal level betides 20Mbps data channel low-signal levels, the tolerance interval of signal level has reduced.If with constant PPH, is to avoid this degradation need transmit less CDV signal at the 20Mbps data channel at all channels then.
When in conjunction with the special execution mode explanation of sketching above when of the present invention, many alternative methods concerning the people that those are skilled in technique are revised and change is conspicuous.Therefore, be to think explanation rather than restriction as above-mentioned preferred implementation of the present invention.Can do various changes under the spirit and scope of the present invention situation that describes in detail in the patent claim below not departing from.
Claims (34)
1, a communication network comprises:
One central office; With
A plurality of first transmission mediums, each is used for the central office is connected with at least one terminal unit of a plurality of terminal units, the central office sends first broadcast singal along each of a plurality of first transmission mediums, and the terminal unit of central office along distributing signal of one of a plurality of first transmission mediums transmission at least one appointment.
2, the communication network of claim 1 also comprises a plurality of intermediate medium nodes and a plurality of second transmission medium, and each in a plurality of intermediate medium nodes is connected between one of a plurality of second transmission mediums of one of corresponding a plurality of first transmission mediums and correspondence.
3, the communication network of claim 2 wherein is connected the central office with each of a plurality of second transmission mediums with the subset of corresponding a plurality of terminal units.
4, the communication network of claim 2 comprises that also the 3rd transmission medium is connected the central office with in a plurality of intermediate medium nodes each, and the central office sends second broadcast singal from the central office along another transmission medium on each to a plurality of intermediate medium nodes.
5, the communication network of claim 4, wherein each first broadcast singal in the intermediate medium node and second broadcast singal combines and send the signal of combination along each of a plurality of second transmission mediums.
6, the communication network of claim 4, wherein the 3rd transmission medium comprises a Fiber Node, one connects the optical fiber of central office and Fiber Node, with a plurality of each be connected the order wire of this Fiber Node and at least one intermediate medium node.
7, the communication network of claim 4, wherein second broadcast singal is an analog video signal.
8, the communication network of claim 1, wherein first broadcast singal is a digital video signal.
Therefore 9, the communication network of claim 1, wherein distributing signal is an encoded signals (encodedsignal), has only the terminal unit of appointment this distributing signal that could receive and decode.
10, the communication network of claim 1, wherein distributing signal is the signal (codedsingnal) of an encode, only for appointed terminal unit decoding.
11, the communication network of claim 1, wherein the central office comprises that power controller is used to control along every hertz power of first broadcast singal of each transmission of a plurality of first transmission mediums.
12, the communication network of claim 11, wherein output control device requires to control every hertz power of first broadcast singal according to the bit error rate performance of signal on the terminal unit.
13, the communication network of claim 1, wherein central office comprises that a transmitter is used for an intermediate medium node that sends distributing signal and the sub-device of first broadcast singal to physical connection to a plurality of terminal units from the central office along a plurality of first transmission mediums.
14, the communication network of claim 1, each of wherein a plurality of first transmission mediums comprises an optical fiber.
15, the communication network of claim 1, wherein the central office comprises the broadcast singal of switching device control as the transmission of first broadcast singal.
16, the communication network of claim 1, wherein the central office comprises that a switching device controls a plurality of first transmission mediums and receive first broadcast singal.
17, the communication network of claim 1, wherein distributing signal provides the reciprocal exchange of business (switchedservice).
18, a communication network comprises:
Be connected to first transmission medium of central office, first broadcasting service is transmitted in this central office on first transmission medium;
With independently a plurality of second transmission mediums of first transmission medium, second broadcasting service is transmitted in this central office on a plurality of second transmission mediums;
A plurality of intermediate medium nodes, in a plurality of intermediate medium nodes each is connected to divides other to go up to receive second broadcasting service and to connect to receive first broadcasting service in a plurality of second transmission mediums, each intermediate medium node makes up first broadcasting service and second broadcasting service; With
A plurality of passive transmission mediums, each is used for an intermediate medium node is connected on the sub-device of a correspondence of a plurality of terminal units, and wherein a plurality of intermediate medium nodes send first broadcasting service of combination and second broadcasting service with by each reception of a plurality of terminal units along a plurality of passive transmission mediums.
19, the communication network of claim 18, wherein the central office comprises that a distributor is used for along one of a plurality of second transmission mediums distributing signal being transferred to corresponding one of a plurality of intermediate medium nodes, and distributing signal is transferred on the terminal unit of an appointment along one of passive transmission medium again.
20, the communication network of claim 19, wherein distributing signal is the frequency-division multiplex singal that is transferred to the terminal unit of appointment.
21, the communication network of claim 19, wherein the central office comprises that output control device is used to control every hertz power of second broadcasting service.
22, the communication network of claim 19, wherein the central office comprises that output control device is used for every hertz power of Control Allocation signal.
23, the communication network of claim 19, wherein the central office comprises that channel dividing arrangement is used to control the broadcasting as second broadcast traffic transmissions.
24, a data transmission system comprises:
One central office;
One is connected to the transmission medium of a plurality of terminal units with the central office, and a plurality of digital services are transmitted along transmission medium in the central office; With
The digital service signal that every channel power that bit error rate performance according to the digital service that provides requires to determine comes the analog submodule carrier wave of control transmission medium is provided output control device.
25, the data transmission system of claim 24, wherein digital service comprises broadcasting service and at least one distribution service.
26, the data transmission system of claim 24 wherein adopts at least a modulation system and at least a error correction coding to come the transmission of digital business.
27, a method that from the central office business is transferred to a plurality of terminal units, method comprises:
Transmit first broadcasting service from the central office along a plurality of first transmission mediums to a plurality of nodes; With
Transmit distribution service along one of a plurality of transmission mediums to the node relevant with the terminal unit of appointment.
28, patent requires 27 method, also comprises:
Transmit second broadcasting service along the transmission medium that separates to a plurality of nodes;
First broadcasting service, second broadcasting service and distribution service combine on one of a plurality of nodes; With
Along the signal of passive transmission medium transmission combination, wherein passive transmission medium is to be used for being connected on the sub-device of terminal unit that a plurality of terminal units comprise appointment.
29, the method for claim 28, wherein distribution service is specially to the encoded signals of the terminal unit of appointment.
30, patent requires 27 method, also comprises the every hertz of professional power of requirement control according to the business that is provided to terminal unit.
31, patent requires 27 method, and wherein first broadcasting service is a digital video service.
32, patent requires 27 method, also comprises according to the broadcasting preference of the sub-device of the terminal unit relevant with node controlling first broadcasting service.
33, one between central office and a plurality of terminal unit method for communicating, method comprises:
Transmit first broadcasting service from the central office at first transmission medium;
Transmit second broadcasting services from the central office at a plurality of second transmission mediums;
On a plurality of intermediate medium nodes, receive and make up first broadcasting service and second broadcasting service; With
Continue to use first broadcasting service and second broadcasting service that the 3rd transmission medium that is connected to corresponding a plurality of terminal units sends combination from a plurality of intermediate medium nodes.
34, patent requires 33 method, also comprises from the central office along one of a plurality of second transmission mediums to one of a plurality of intermediate medium nodes of the terminal unit that is used for being connected to appointment transmission distributing signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN97122472A CN1189028A (en) | 1996-11-12 | 1997-11-11 | Network apparatus and method to provide compressed digital video over mini-fiber nodes |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US747,708 | 1996-11-12 | ||
| CN97122472A CN1189028A (en) | 1996-11-12 | 1997-11-11 | Network apparatus and method to provide compressed digital video over mini-fiber nodes |
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| Publication Number | Publication Date |
|---|---|
| CN1189028A true CN1189028A (en) | 1998-07-29 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN97122472A Pending CN1189028A (en) | 1996-11-12 | 1997-11-11 | Network apparatus and method to provide compressed digital video over mini-fiber nodes |
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| CN (1) | CN1189028A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102549952A (en) * | 2011-12-09 | 2012-07-04 | 华为技术有限公司 | Method, system and device for bandwidth resource management |
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1997
- 1997-11-11 CN CN97122472A patent/CN1189028A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102549952A (en) * | 2011-12-09 | 2012-07-04 | 华为技术有限公司 | Method, system and device for bandwidth resource management |
| WO2013082813A1 (en) * | 2011-12-09 | 2013-06-13 | 华为技术有限公司 | Bandwidth resource management method, system, and device |
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