CN102378073A - Ethernet over cable (EoC) system, and co-cable compatible method for EoC system and existing system - Google Patents
Ethernet over cable (EoC) system, and co-cable compatible method for EoC system and existing system Download PDFInfo
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Abstract
The invention discloses an Ethernet over cable (EoC) system, and a co-cable compatible method for the EoC system and an existing system. The co-cable compatible method comprises the following steps of: 1, setting sending energy of an orthogonal frequency division multiplexing (OFDM) sub carrier corresponding to a working frequency band occupied by the existing system as zero at an EoC sending end; and filtering leakage interference of sub carriers in the working frequency band on the existing system by adopting an adjustable digital filter, wherein the sub carriers do not include the OFDM sub carrier occupied by the existing system; and 2, filtering interferences of the existing system on the EoC receiving end by adopting the adjustable digital filter at the EoC receiving end. The EoC system and the existing systems, such as a cable modem termination system (CMTS), a bidirectional set top box and the like which are at the same frequency band, can coexist in a co-cable manner and cannot interfere with each other. By the co-cable compatible method, the EoC system can fully use most of available frequency bands except for the extremely narrow working frequency band occupied by the existing system.
Description
Technical field
The invention belongs to communication technical field, relate to modulation of a kind of signal and filtering method, relate in particular to a kind of EoC system and existed system common cable compatibility method, reach the EoC system.
Background technology
Follow the digitization of broadcasting process, accelerate development, build broadband, two-way cable TV network, obtained well recognized for the cable TV subscriber provides comprehensive multimedia service such as Internet, VoD, interactive television for cooperating the DTV multiple business.And the access of China's broadcasting and TV coaxial cable covering reaches 1.5 hundred million users; Be to cover one of Wireline the most widely; Simultaneously coaxial cable has characteristics such as broadband, high bandwidth, therefore how on existing coaxial network, to carry Ethernet, IP operation, EoC is provided, and (Ethernet Over Cable) becomes the focus of various technology.
The EoC technology is to adopt frequency multiplexing technique that Ethernet data signal and cable TV signal are placed on realization cable transmission altogether in the same coaxial cable.According to the cable TV network frequency division standard of China, the Ethernet data signal is transmitted at 65MHz or below the 45MHz frequency range, cable TV signal can be realized the common cable transmission of two signals, and be independent of each other in the above band transmissions of 87MHz.87-862MHz is cable TV signal and the forward data transmission that is used for forward in the cable TV network, and 5-65MHz is used for the reverse data transmission.Low-frequency range in the cable TV network is the frequency range that noise is concentrated, and exists because various intrusion noises that environmental interference causes and converge the funnel noise because tree brought.
Next band coaxial cable broadband access will be adopted the EoC technology, and EoC will use the working frequency range of all or part of frequency band of 5-65MHz as the EoC system.Present some existing systems in the coaxial cable also use sub-fraction bandwidth in this frequency range as the working frequency range of return path like bi-directional set-top box or CMTS (Cable Modem Termination Systems) system.How to let the other system coexistence of EoC system and the existing CMTS of comprising system in the network compatible and not disturb mutually be to realize the key of existing network to next band EoC network smooth transition.For the coexistence that realizes EoC and existed system can be taked following schemes:
1, EoC is laid in the new network that does not have CMTS and bi-directional set-top box.The big limitations of this scheme the popularization of EoC.
2, CMTS in the existing network and bi-directional set-top box are removed, substitute with the EoC system.The workload that the enforcement of this scheme expends is big, and needs to interrupt the operate as normal of existing network system.
The working frequency range that 3, will have the system in the network is repartitioned and is set, with the high-end most of frequency range that is made as the return path of existed system and will be left of this frequency range of the 5-65M working frequency range as EoC.This scheme also need be interrupted the operate as normal of existing network system.
4, at present the existed system in the network mainly uses partial-band among the 30-50M as return path, can the working frequency range of new EoC system be located at the low-limit frequency following (below 30M) of the working band of existed system.This scheme need not to do any change to existing network, but big limitations the available bandwidth of EoC, high-end most of frequency band all be wasted (even very narrow frequency range that existed system has only used 0.5-8M not wait).
Summary of the invention
Technical problem to be solved by this invention is: the common cable compatibility method that a kind of EoC system and existed system are provided;
In addition, the present invention also provides a kind of EoC system, and this system can cable be compatible altogether with existed system.
For solving the problems of the technologies described above, the present invention adopts following technical scheme.
The common cable compatibility method of a kind of EoC system and existed system, this method may further comprise the steps:
Step 1, at the EoC transmitting terminal, the transmission energy of the OFDM subcarrier of the working frequency range correspondence that existed system is shared is set to O; Adopt then adjustable digital filter come in the filtering working frequency range other subcarriers except that the shared OFDM subcarrier of existed system to existed system influential leakage disturb;
Step 2 at the EoC receiving terminal, adopts adjustable digital filter to come the filtering existed system to the influential interference of EoC receiving terminal.
As a kind of preferred version of the present invention, said existed system uses the working frequency range of 5-65MHz; Said existed system comprises bi-directional set-top box, or/and the CMTS system.
As another kind of preferred version of the present invention, said adjustable digital filter comes the flexible parameter of setting self according to the frequency band division of existed system, and said parameter comprises centre frequency, bandwidth or stopband attenuation.
A kind of EoC system, this EoC system and existed system cable altogether are compatible, comprise transmitting terminal and receiving terminal;
The transmitting terminal of said EoC system comprises the OFDM modulator, sends tunable digital filter, IFFT module, DAC module; Said OFDM modulator is modulated into the OFDM subcarrier in order to will send data message; Said transmission tunable digital filter links to each other with the output of said OFDM modulator, in order in the filtering OFDM subcarrier the influential leakage of existed system is disturbed; Said IFFT module is arranged between said OFDM modulator and the said transmission tunable digital filter, in order to the OFDM subcarrier of OFDM modulator output is made inverse fourier transform; Said DAC module links to each other with the output of said transmission tunable digital filter, becomes analog signal in order to the digital signal conversion that will send tunable digital filter output, is sent to channel then and transmits.
The receiving terminal of said EoC system comprises the reception tunable digital filter, ofdm demodulator, ADC module, FFT module; Said reception tunable digital filter is in order to receiving the OFDM subcarrier of said transmission tunable digital filter output, and the OFDM subcarrier influential interference of filtering existed system to receiving; Said ofdm demodulator links to each other with said reception tunable digital filter, in order to the OFDM subcarrier de furnishing receiving data information with said reception tunable digital filter output; Said ADC module links to each other with the input of said reception tunable digital filter, in order to becoming digital signal from the analog signal conversion that channel receives, imports said reception tunable digital filter then; Said FFT module is arranged between said ofdm demodulator and the said reception tunable digital filter, makes Fourier transform in order to the output signal to said reception tunable digital filter.
As a kind of preferred version of the present invention, said transmission tunable digital filter is in order to set flexibly the parameter of self according to the frequency band division of existed system, and said parameter comprises centre frequency, bandwidth or stopband attenuation.
As another kind of preferred version of the present invention, said reception tunable digital filter is in order to set flexibly the parameter of self according to the frequency band division of existed system, and said parameter comprises centre frequency, bandwidth or stopband attenuation.
Beneficial effect of the present invention is: EoC system of the present invention and can and not disturb mutually with the cable coexistence with existed systems such as the CMTS of frequency range, bi-directional set-top boxes; Cable compatibility method altogether of the present invention makes the EoC system under the situation that does not change existed system, make full use of the most available band except that the shared very narrow working frequency range of existed system, and cost be low.
Description of drawings
Fig. 1 is the system block diagram of EoC of the present invention system.
Embodiment
Do further explain below in conjunction with the accompanying drawing specific embodiments of the invention.
Embodiment one
Present embodiment provides a kind of EoC system, and this EoC system and existed system cable altogether are compatible, as shown in Figure 1, and said EoC system comprises transmitting terminal and receiving terminal.
The transmitting terminal of said EoC system comprises the OFDM modulator, sends tunable digital filter, IFFT module, DAC module; Said OFDM modulator is modulated into the OFDM subcarrier in order to will send data message; Said transmission tunable digital filter links to each other with the output of said OFDM modulator, in order in the filtering OFDM subcarrier the influential leakage of existed system is disturbed; Said transmission tunable digital filter can set flexibly the parameter of self according to the frequency band division of existed system, and said parameter comprises centre frequency, bandwidth or stopband attenuation.Said IFFT module is arranged between said OFDM modulator and the said transmission tunable digital filter, in order to the OFDM subcarrier of OFDM modulator output is made inverse fourier transform; Said DAC module links to each other with the output of said transmission tunable digital filter, becomes analog signal in order to the digital signal conversion that will send tunable digital filter output, is sent to channel then and transmits.
The receiving terminal of said EoC system comprises the reception tunable digital filter, ofdm demodulator, ADC module, FFT module; Said reception tunable digital filter is in order to receiving the OFDM subcarrier of said transmission tunable digital filter output, and the OFDM subcarrier influential interference of filtering existed system to receiving; Said reception tunable digital filter can set flexibly the parameter of self according to the frequency band division of existed system, and said parameter comprises centre frequency, bandwidth or stopband attenuation.Said ofdm demodulator links to each other with said reception tunable digital filter, in order to the OFDM subcarrier de furnishing receiving data information with said reception tunable digital filter output; Said ADC module links to each other with the input of said reception tunable digital filter, in order to becoming digital signal from the analog signal conversion that channel receives, imports said reception tunable digital filter then; Said FFT module is arranged between said ofdm demodulator and the said reception tunable digital filter, makes Fourier transform in order to the output signal to said reception tunable digital filter.
EoC system of the present invention and can and not disturb mutually with the cable coexistence with existed systems such as the CMTS of frequency range, bi-directional set-top boxes.
Embodiment two
The present invention adopts the OFDM modulation technique; At the EoC transmitting terminal; The transmission energy of the OFDM subcarrier of the working frequency range correspondence that existed system is shared is set to O; Though this has significantly reduced the interference of EoC system to existed system, because the leakage of other subcarriers is disturbed, the present invention adopts adjustable digital filter to come filtering that the leakage of influential other subcarriers of existed system is disturbed after the OFDM modulator.
At the EoC receiving terminal; Though the interference of existed systems such as CMTS has only influenced the no subcarrier of a very little part; But for to avoid the influence of the interference of existed system to other parts of EoC receiving terminal, present embodiment after the ADC module, to use adjustable digital filter to come the filtering existed system to the influential interference of EoC receiving system.
The parameter of tunable digital filter is (like centre frequency; Bandwidth; Stopband interference etc.) can come to set flexibly according to the frequency band division of existed system,, only need parameter through software set corresponding digital filter even also need change the frequency band division of systems such as CMTS in the future; Just can make the EoC system adapt to new frequency band division, can further remove of the interference of EoC system existed system through adjusting these parameters.For example; If existed system uses the frequency range of 40～43MHz; Then can the stopband attenuation of the tunable digital filter among the present invention be made as 30dB, the stopband frequency range is made as 39～44MHz, simultaneously the corresponding OFDM subcarrier energy of this frequency band of 39～44MHz all is made as 0.If existed system uses the frequency range of 36～42MHz, then can the stopband attenuation of the tunable digital filter among the present invention be made as 30dB, the stopband frequency range is made as 35～43MHz, simultaneously the corresponding OFDM subcarrier energy of this frequency band of 35～43MHz all is made as 0.
Present embodiment provides the common cable compatibility method of a kind of EoC system and existed system, and this method may further comprise the steps:
Step 1, at the EoC transmitting terminal, the transmission energy of the OFDM subcarrier of the working frequency range correspondence that existed system is shared is set to O; Adopt then adjustable digital filter come in the filtering working frequency range other subcarriers except that the shared OFDM subcarrier of existed system to existed system influential leakage disturb;
Step 2 at the EoC receiving terminal, adopts adjustable digital filter to come the filtering existed system to the influential interference of EoC receiving terminal.
Said adjustable digital filter comes the flexible parameter of setting self according to the frequency band division of existed system, and said parameter comprises centre frequency, bandwidth or stopband attenuation.Said existed system uses the working frequency range of 5-65MHz.Said existed system comprises bi-directional set-top box, or/and the CMTS system.If the OFDM modulation system is used in combination with error correcting code in the system; For not changing data format; Can the pairing data of the repressed subcarrier of OFDM all be made as unnecessary bit (Dummy Bits); Can set different bandwidth of rejection like this, and need not to change the coded format of error correcting code encoder.
Altogether cable compatibility method of the present invention makes the EoC system can be under the situation that does not change existed system; Through the parameter of flexible setting tunable digital filter, reached the purpose that makes full use of the most available band except that the shared very narrow working frequency range of existed system; That has not only realized EoC system and existed system does not disturb compatibility mutually, and has promoted the popularization and the application of EoC system, has thoroughly solved the difficult problem of existing network to next band EoC network smooth transition.
Utilize the compatibility coexistence of existing techniques in realizing EoC system and existed system to have following 2 aspect problems:
On the one hand; In order to realize the compatibility coexistence of EoC system and existed system; The emission decay of EoC system on the frequency range of existed system need reach more than the 50dB; If only adopt numeral or analog filter to reach the realization cost that above requirement can increase filter greatly, if the control hardware cost can only be a cost to waste more available band then.
On the other hand; If the method that adopts the OFDM subcarrier to suppress as other system reduces the influence of EoC system to existed system; Be to be difficult to reach (though the realization cost that subcarrier suppresses is low, and the available band of waste is few) greater than the requirement of 50dB decay.
Compared with prior art, the present invention requires (like 30dB) through the decay that lets filter only bear part, only sacrifices the purpose that limited available band reaches the realization cost of saving a large amount of filters.The present invention simultaneously makes full use of OFDM subcarrier inhibition method to high these characteristics of available band utilance; OFDM subcarrier inhibition method is used in combination with digital filter; Neither waste available band and saved hardware implementation cost again; And satisfied the emission decay requirement of EoC system on the frequency range of existed system, realized doulbe-sides' victory.
Here description of the invention and application is illustrative, is not to want with scope restriction of the present invention in the above-described embodiments.Here the distortion of the embodiment that is disclosed and change are possible, and the replacement of embodiment is known with the various parts of equivalence for those those of ordinary skill in the art.Those skilled in the art are noted that under the situation that does not break away from spirit of the present invention or substantive characteristics, and the present invention can be with other forms, structure, layout, ratio, and realize with other elements, material and parts.
Claims (9)
1. the common cable compatibility method of EoC system and existed system, it is characterized in that: said cable compatibility method altogether may further comprise the steps:
Step 1, at the EoC transmitting terminal, the transmission energy of the OFDM subcarrier of the working frequency range correspondence that existed system is shared is set to O; Adopt then adjustable digital filter come in the filtering working frequency range other subcarriers except that the shared OFDM subcarrier of existed system to existed system influential leakage disturb;
Step 2 at the EoC receiving terminal, adopts adjustable digital filter to come the filtering existed system to the influential interference of EoC receiving terminal.
2. the common cable compatibility method of EoC system according to claim 1 and existed system is characterized in that: said existed system uses the working frequency range of 5-65MHz; Said existed system comprises bi-directional set-top box, or/and the CMTS system.
3. the common cable compatibility method of EoC system according to claim 1 and existed system; It is characterized in that: said adjustable digital filter comes the flexible parameter of setting self according to the frequency band division of existed system, and said parameter comprises centre frequency, bandwidth or stopband attenuation.
4. EoC system is characterized in that: said EoC system and existed system cable altogether are compatible, comprise transmitting terminal and receiving terminal;
The transmitting terminal of said EoC system comprises:
The OFDM modulator is modulated into the OFDM subcarrier in order to will send data message;
Send tunable digital filter, link to each other with the output of said OFDM modulator, in order in the filtering OFDM subcarrier to the influential leakage interference of existed system;
The receiving terminal of said EoC system comprises:
Receive tunable digital filter, in order to receiving the OFDM subcarrier of said transmission tunable digital filter output, and the OFDM subcarrier influential interference of filtering existed system to receiving;
Ofdm demodulator links to each other with said reception tunable digital filter, in order to the OFDM subcarrier de furnishing receiving data information with said reception tunable digital filter output.
5. EoC according to claim 4 system is characterized in that: said existed system uses the working frequency range of 5-65MHz; Said existed system comprises bi-directional set-top box, or/and the CMTS system.
6. EoC according to claim 4 system is characterized in that, the transmitting terminal of said EoC system also comprises:
The IFFT module is arranged between said OFDM modulator and the said transmission tunable digital filter, in order to the OFDM subcarrier of OFDM modulator output is made inverse fourier transform;
The DAC module links to each other with the output of said transmission tunable digital filter, becomes analog signal in order to the digital signal conversion that will send tunable digital filter output, is sent to channel then and transmits.
7. EoC according to claim 4 system is characterized in that: said transmission tunable digital filter is in order to set flexibly the parameter of self according to the frequency band division of existed system, said parameter comprises centre frequency, bandwidth or stopband attenuation.
8. EoC according to claim 4 system is characterized in that: the receiving terminal of said EoC system also comprises:
The ADC module links to each other with the input of said reception tunable digital filter, in order to becoming digital signal from the analog signal conversion that channel receives, imports said reception tunable digital filter then;
The FFT module is arranged between said ofdm demodulator and the said reception tunable digital filter, makes Fourier transform in order to the output signal to said reception tunable digital filter.
9. EoC according to claim 4 system is characterized in that: said reception tunable digital filter is in order to set flexibly the parameter of self according to the frequency band division of existed system, said parameter comprises centre frequency, bandwidth or stopband attenuation.
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| CN201010252133.XA CN102378073B (en) | 2010-08-12 | 2010-08-12 | Ethernet over cable (EoC) system, and co-cable compatible method for EoC system and existing system |
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| CN201010252133.XA CN102378073B (en) | 2010-08-12 | 2010-08-12 | Ethernet over cable (EoC) system, and co-cable compatible method for EoC system and existing system |
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| CN102378073B CN102378073B (en) | 2015-07-01 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103780968B (en) * | 2012-10-17 | 2017-02-08 | 上海未来宽带技术股份有限公司 | Double-working mode CATV module and system |
| CN107144741A (en) * | 2017-06-30 | 2017-09-08 | 中国科学院云南天文台 | Anti-interference radio astronomy radiometer system based on agile transceiver |
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