CN1852379B - Method for activating VDSL/VDSL2 USO channel - Google Patents

Abstract

The method is in use for communication system including communication sites in office end and communication sites in remote end connected through twisted pair wire. In G.993.2 channel discovery phase, measuring SNR of frequency points in US0 and US1 channels obtains data rate of accepted load by US0 and US1 channels so as to obtain transmission rates of US0 and US1 channels. Comparing rate of US0 channel with rate of US1 channel decides whether it is needed to activate US0 channel.

Description

The method of a kind of activating VDSL/VDSL2 US0 channel

Technical field

The present invention relates to the communications field, especially relate to the method that activates the US0 channel in a kind of very high bit rate digital subscriber line (VDSL) and/or second generation VDSL (VDSL2) data communication system.

Background technology

VDSL (Very High-bit-rate Digital Subscriber Line) is called very high bit rate digital subscriber line again, and VDSL2 (Second generation VDSL) is second generation VDSL.From technical standpoint, it is the next-generation technology of ADSL (Asymmetric Digital Subscriber Line) (AsymmetricalDigital Subscriber Line) that VDSL/VDSL2 can be considered, in short distance, the speed that it provides on a pair of plain old telephone twisted-pair feeder substantially exceeds the speed of ADSL.In 300 meters scopes, the VDSL transmission rate can reach 52Mbps; In 1.5 kilometer range, transmission rate generally can reach 16Mbps.Because VDSL provides bigger bandwidth, so can satisfy more business demand, comprise transmission hi-fi music and high definition TV, the pure MPEG2 information flow of multichannel, be that real full-service inserts means.In addition, the speed of VDSL and Ethernet speed are very approaching, can be used as the extension of Ethernet fully, and distance is at " big Ethernet " more than 1 kilometer between the formation network node, and VDSL is the solution preferably that realizes that sub-district LAN inserts.

The VDSL/VDSL2 data communication system, as shown in Figure 1, it comprises the VTU-C (Central Office VDSL Terminal Unit) of a local side communication site and the VTU-R (Remote VDSL Terminal Unit) of a remote communication station point, two communication sites communicate by a circuit, the signal that website VTU-C is sent to website VTU-R is called downstream signal, and signal in opposite direction is called upward signal.In the communication process, website VTU-C and website VTU-R support plurality of operating modes respectively, and these patterns are used different frequency bands.

VDSL/VDSL2 mainly is at the short twisted pair telephone optimal design of 1 to 1.5 km.The channel difference that VDSL/VDSL2 defines in the each department, various countries, but 4-6 channel generally arranged.Fig. 2 is a typical example, and 2-3 downlink channel wherein arranged, 2-3 upstream channel, and the initial frequency of first upstream channel US1 is generally more than 3MHz.

In addition, VDSL/VDSL2 has also defined the 0th upstream channel US0, US0 channel initial frequency f _OLBe 0/25/138kHz, stop frequency f _OHBe 138/276kHz.For the twisted pair telephone greater than a km, because the circuit fading channel is excessive, the US1 channel almost can not be used for transmitting upstream data.Because the US0 channel is low frequency domain channel, fading channel is less, therefore, if VDSL/VDSL2 local side and remote equipment are all supported the US0 channel, local side and remote equipment can activate the US0 channel by Handshake Protocol, and the VDSL/VDSL2 business can be opened operation on the long-distance telephone twisted-pair feeder more than the km.

For the opportunity of activating the US0 channel, current simple method is to estimate the length of twisted pair telephone in the VDSL/VDSL2 initialization procedure according to the fading channel of measuring, when the length of twisted pair telephone greater than a thresholding, for example a km then activates the US0 channel.In order to reduce interference, the upstream channel US1-US3 channel that almost can not transmit all high frequencies of data can also be closed simultaneously All other routes.

Power in the fading channel LOSS of certain frequency f (f)=emitted power-reception.

Line length $L=\mathrm{LOSS}\left(f\right)/\left(K\sqrt{f}\right)$ , wherein K is a circuit model parameter according to Theoretical Calculation.In practice, the fading channel difference of different frequent points, so the difference of LOSS (f) is very big, and also different according to the line length of LOSS (f) estimation, use always and can get maximum, average or minimum value.

There is following shortcoming in current method:

1. only consider fading channel in the current method, do not considered the influence of circuit noise.If circuit noise is bigger, even line length is lower than the activation thresholding, the US1 channel also may almost can not be used to transmit upstream data, even perhaps can transmit upstream data, transfer rate is still lower, as 10Kbps.If activate the US0 channel, may obtain the transfer rate of hundreds of Kbps.

2. estimate that with the method for measured channel decay the length of twisted pair telephone is generally more rough in the current method, the threshold setting that activates the US0 channel is difficult to control accurately.If threshold setting is too small, circuit can activate the US0 channel and close the US1-US3 channel in shorter length, but this moment the US1-US3 channel can also be used to higher rate (＞1Mbps) transmit upstream data, can only transmit upstream data with the speed of 1Mbps and the US0 channel is the highest, reduce up transfer rate; If threshold setting is excessive, circuit can't transmit upstream data with the US1-US3 channel in certain length that is lower than thresholding, can cause circuit training (Training) failure, to such an extent as to cause length can't open the VDSL/VDSL2 business to the circuit that activates between thresholding in certain length distance.

Summary of the invention

Deficiency according to US0 channel technology in above existing activating VDSL/VDSL2 data communication system the object of the present invention is to provide a kind of method, can determine to activate the opportunity of US0 channel more accurately.

For realizing this purpose, the invention provides the method for a kind of activating VDSL/VDSL2 US0 channel, comprise step: the signal to noise ratio of measuring US0 channel and US1 channel frequency, but obtain US0 channel and US1 channel data carried by data rate, and then the transmission rate of acquisition US0 channel and US1 channel, relatively whether the transmission rate of US0 channel and US1 channel activates the US0 channel with decision; The transmission rate of described acquisition US0 channel and US1 channel is: the aggregate date rate * character rate of the transmission rate of US0 channel or US1 channel=US0 channel or US1 channel; The aggregate date rate of described US0 channel or US1 channel is that the data transfer rate with US0 channel or all frequency actual bearer of US1 channel adds up and can obtain the aggregate date rate that US0 channel or US1 channel can carry.

The signal to noise ratio of described measurement US0 channel and US1 channel frequency is in channel discovery phase G.993.2, when the ascending power of determining US0 channel and US1 channel frequency reduces, measure the static noise and the fading channel of US0 channel and the up frequency of US1 channel, and according to the power spectral density of selected VDSL/VDSL2 channel plan, dispose corresponding noise margin and coding gain, determine the signal to noise ratio of US0 channel and the up frequency of US1 channel.

The ascending power reduction of described definite US0 channel and US1 channel frequency is to determine according to the local side communication site of estimation and the electrical length of the twisted pair telephone between the remote communication station point.

The static noise and the fading channel of described US0 channel and the up frequency of US1 channel change with frequency.

The signal to noise ratio of described definite US0 channel and the up frequency of US1 channel is:

The signal to noise ratio of frequency (dB)=frequency power spectral density (dB)-fading channel (dB)-noise margin (dB)+coding gain (dB).

Described character rate is got the numerical value of VDSL/VDSL2 definition.

The numerical value of described VDSL/VDSL2 definition is 4000 or 8000.

Whether the transmission rate of described relatively US0 channel and US1 channel activates the US0 channel with decision is that then the local side communication site can close the US1-US3 channel simultaneously by message activation US0 channel if the US0 channel has big transmission rate; If the US1 channel has big transmission rate, the local side communication site closes the US0 channel by message.

The present invention measures the signal to noise ratio of US0 channel and US1 channel frequency in channel discovery phase G.993.2, both consider fading channel, considered the influence of circuit noise again, and can calculate the transmission rate of US0 channel and US1 channel, accurately judging the activation opportunity of US0 channel, is a kind of more accurate scheme; The present invention is fully according to existing VDSL/VDSL2 standard in addition, can with the VDSL/VDSL2 hardware compatibility of standard.

Description of drawings

Fig. 1 is a VDSL/VDSL2 data communication system schematic diagram.

Fig. 2 is a kind of VDSL/VDSL2 channel frequency distribution diagram.

Fig. 3 is the schematic diagram in 5 stages of VDSL/VDSL2 circuit initialization.

Fig. 4 is a VDSL/VDSL2 channel selection flow chart of the present invention.

Embodiment

According to signal processing theory, the signal to noise ratio of frequency (tones) is both to have considered fading channel, considers the influence of circuit noise again.The method of activation of the present invention US0 channel be exactly signal to noise ratio with US0 channel and US1 channel frequency serve as the opportunity that the US0 channel is determined to activate in the basis.According to the signal to noise ratio of US0 channel and US1 channel frequency, but obtain US0 channel and US1 channel data carried by data rate, and then obtain the transmission rate of US0 channel and US1 channel, relatively whether the transmission rate of US0 channel and US1 channel activates the US0 channel with decision.

The initialization procedure of VDSL/VDSL2 circuit divides 5 stages, as shown in Figure 3, is followed successively by G.994.1 handshake phase, channel discovery phase (Channel Discovery Phase) G.993.2, training stage, Multiple Channel Analysis stage and switching phase.

With the VDSL2 data communication system is example, and G.994.1 handshake phase is to select the working method stage by VTU-C and VTU-R by exchange message, as ADSL, and ADSL2+, VDSL, VDSL2 etc.; Channel discovery phase is to determine the stage of the fundamental characteristics of channel, as locked clock etc.; Training stage is the stage of training time-domain equalizer; Multiple Channel Analysis and switching phase are the labor characteristics of channel, determine the stage of transmission parameter.

The equipment of method utilization of the present invention is the signal processing in original measuring equipment, implements by following proposal:

In channel discovery phase (Channel Discovery Phase) G.993.2, when the ascending power of determining US0 channel and US1 channel frequency reduces (UPBO), determine the signal to noise ratio of US0 channel and the up frequency of US1 channel.

G.993.2 in the standard UPBO that determines US0 channel and US1 channel frequency according to the electrical length of the twisted pair telephone of estimating, UPBO is at the Signal to Noise Ratio Margin that guarantees the up channel receiving terminal, satisfies under the prerequisite of ascending power spectrum density template (PSD MASK) regulation, reduces the mechanism of transmitting power as far as possible.Being embodied as of its mechanism:

1.VTU-R the electrical length of measurement circuit (k10), electrical length are to adopt according to the attenuation characteristic of circuit to be equal to the equivalent length that method of the prior art is estimated.

According to k10 and power spectral density template (PSD MASK) determine the new uplink transmission power TxPSD of frequency f (k10, f):

TxPSD(k10，f)＝PSDREF(f)+LOSS(k10，f)+3.5[dB]

$\mathrm{LOSS}(k10,f)=k10\sqrt{f}---\left[\mathrm{dB}\right]$

Can measure the US0 channel that changes with frequency and the static noise and the fading channel of the up frequency of US1 channel at channel discovery phase measuring equipment G.993.2, and according to the power spectral density of selected VDSL/VDSL2 channel plan (Bandplan), dispose corresponding noise margin and coding gain, can determine the signal to noise ratio of US0 channel and the up frequency of US1 channel.

The signal to noise ratio of US0 channel or US1 channel frequency can be used following formulate:

The signal to noise ratio of frequency (dB)=frequency power spectral density (dB)-fading channel (dB)-noise margin (dB)+coding gain (dB)

The signal to noise ratio of frequency generally in 0～100dB scope, need deduct fixing noise margin span, as 9.5 (dB) when calculating the frequency transmission rate.

Concerning single frequency point, general every 3dB can carry the data transfer rate of 1 bit.When signal to noise ratio was 45dB, single frequency point can carry the data transfer rate of 15 bits, and frequency reaches its maximum data transmission capabilities.The data transfer rate of US0 channel or all frequency actual bearer of US1 channel added up to obtain the aggregate date rate that US0 channel or US1 channel can carry.

The transmission rate of US0 channel or US1 channel and the aggregate date rate of its carrying have following relation:

The aggregate date rate * character rate of the transmission rate of US0 channel or US1 channel=US0 channel or US1 channel.Wherein, character rate is got the numerical value of VDSL/VDSL2 definition, as 4000 per seconds or 8000 per seconds.

In sum, but can obtain US0 channel and US1 channel data carried by data rate, and then obtain the transmission rate of US0 channel and US1 channel by the signal to noise ratio of US0 channel and the up frequency of US1 channel.

Fig. 4 is a VDSL/VDSL2 channel selection flow chart of the present invention, and as shown in Figure 4, if the US0 channel has big transmission rate, then VTU-C can close the US1-US3 channel simultaneously by message activation US0 channel; If the US1 channel has big transmission rate, VTU-C closes the US0 channel by message.

Enforcement the present invention can accurately be judged the activation opportunity of US0 channel by the signal to noise ratio of US0 channel and US1 channel frequency, selects correct operational mode in channel discovery phase.

The method of US0 channel not only can apply in the current VDSL/VDSL2 system in activating VDSL of the present invention/VDSL2 data communication system, and can apply on the VDSL/VDSL2 basis in follow-on communication system.

The above only is a preferred implementation of the present invention; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (8)

1. the method for activating VDSL/VDSL2 US0 channel, it is characterized in that comprising step: the signal to noise ratio of measuring US0 channel and US1 channel frequency, but obtain US0 channel and US1 channel data carried by data rate, and then the transmission rate of acquisition US0 channel and US1 channel, relatively whether the transmission rate of US0 channel and US1 channel activates the US0 channel with decision;

The transmission rate of described acquisition US0 channel and US1 channel is: the aggregate date rate * character rate of the transmission rate of US0 channel or US1 channel=US0 channel or US1 channel;

The aggregate date rate of described US0 channel or US1 channel is that the data transfer rate with US0 channel or all frequency actual bearer of US1 channel adds up and can obtain the aggregate date rate that US0 channel or US1 channel can carry.

2. the method for claim 1, it is characterized in that: the signal to noise ratio of described measurement US0 channel and US1 channel frequency is in channel discovery phase G.993.2, when the ascending power of determining US0 channel and US1 channel frequency reduces, measure the static noise and the fading channel of US0 channel and the up frequency of US1 channel, and according to the power spectral density of selected VDSL/VDSL2 channel plan, dispose corresponding noise margin and coding gain, determine the signal to noise ratio of US0 channel and the up frequency of US1 channel.

3. method as claimed in claim 2 is characterized in that: the ascending power reduction of described definite US0 channel and US1 channel frequency is to determine according to the local side communication site of estimation and the electrical length of the twisted pair telephone between the remote communication station point.

4. method as claimed in claim 2 is characterized in that: the static noise and the fading channel of described US0 channel and the up frequency of US1 channel change with frequency.

5. method as claimed in claim 2 is characterized in that: the signal to noise ratio of described definite US0 channel and the up frequency of US1 channel is:

The signal to noise ratio of frequency (dB)=frequency power spectral density (dB)-fading channel (dB)-noise margin (dB)+coding gain (dB).

6. the method for claim 1 is characterized in that: described character rate is got the numerical value of VDSL/VDSL2 definition.

7. method as claimed in claim 6 is characterized in that: the numerical value of described VDSL/VDSL2 definition is 4000 or 8000.

8. the method for claim 1, it is characterized in that: whether the transmission rate of described relatively US0 channel and US1 channel activates the US0 channel with decision is if the US0 channel has big transmission rate, then the local side communication site closes the US1-US3 channel simultaneously by message activation US0 channel; If the US1 channel has big transmission rate, the local side communication site closes the US0 channel by message.

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