CN104662833A - Clock recovery method, device and system - Google Patents

Abstract

The present invention relates to the field of communications. Disclosed in an embodiment of the present invention are a clock recovery method, device and system. The method of a central office utilizing an orthogonal sequence to modulate an input signal so as to allow a user end to eliminate far-end crosstalk comprises: the central office respectively generates m DMT signals for each user end, and synchronously transmits the m DMT signals to each user end via n lines connected to n user ends; each line employs one or more pilot tones to transmit the m DMT signals; at least one same pilot tone subset exists in n groups of one or more pilot tones corresponding to the n lines; the coefficients of the pilot tone subsets transmitting the DMT signals on any two lines form an orthogonal matrix, n being greater than or equal to 2, and m being greater than n; and the m DMT signals are used by the user end to acquire the signals consistent with the clock of the central office according to the m DMT signals.

Description

CLOCK RECOVERY METHOD, DEVICE AND SYSTEM

The present invention relates to the communications field, more particularly to a kind of clock recovery method, equipment and system for a kind of clock recovery method, equipment and systems technology field.Background technology

Digital Subscriber Line（Digital Subscriber Line, abbreviation DSL) technology be one kind by UTP（Unshielded Twist Pair, abbreviation UTP) high speed transmission technology that carries out data transmission, i.e. copper wire access technology, had a clear superiority in terms of investment and O＆M compared with intelligent acess technology.

DSL can provide maximum 100Mbps up-downgoing symmetrical rate in theory, still, with the development of various broadband services, demand more and more higher of the client to speed.Current industry is possible to reach 400Mbps to the demand estimation at a specified future date of user rate from original 100Mbps.In order to meet the demand of higher rate, International Telecommunication Union ITU-T has set up Gfast projects to study optical fiber to breakout（Fiber to the Distribution Point, abbreviation FTTdp) under scene, last high-peed connection is provided using copper cash, its target is the access rate that more than 500Mbps is provided in the range of 100m.

In traditional DSL technologies, because transmission range is longer, frequency spectrum is narrower, typically using frequency division multiplexing（Frequency Division Duplexing, abbreviation FDD) duplex mode avoid uplink and downlink signals from interfering.For copper cash broadband access technology Gfast of future generation, due to spread spectrum（Frequency band is up to 250MHz), if using FDD duplex mode, will be very strict to the design requirement of AFE(analog front end).Therefore, ITU-T Q4 have adopted time division duplex（Time Division Duplexing, abbreviation TDD) it is used as Gfast duplex mode.Gfast user terminal is also required to track the clock of local side, in order to which when the clock of user terminal and local side is inconsistent, user terminal needs clock alignment to obtain the signal consistent with local side.Inventor has found that prior art at least has problems with：In Gfast systems, there is strong far-end interference due to spread spectrum so that the signal to noise ratio for the clock synchronizing pilot signal that user terminal is received（Signal to Noise Ratio, abbreviation SNR) it is 4 blunt low, and then cause user terminal from carrying out accurate clock alignment.The content of the invention

The embodiment of the present invention provides a kind of method of clock recovery, equipment and system, and local side modulates input signal using orthogonal sequence so that user terminal can eliminate far-end cross talk, and then carry out accurate Clock alignment and obtain the signal consistent with local side clock.

To reach above-mentioned purpose, the technical scheme that the embodiment of the present invention is used is that first aspect includes there is provided a kind of clock recovery method, methods described：

The local side being connected with n user terminal is respectively that each user terminal generates m dmt signal；The local side sends m dmt signal by the n bar line synchronizations that are connected with the n user terminal to each user terminal；Wherein, every circuit sends the m dmt signal using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the DMT signals is sent on wherein any two lines road and constitutes orthogonal matrix, the user terminal number n is more than or equal to 2, and the m is more than the n;M dmt signal of the user terminal is used for the user terminal for receiving the m dmt signal according to the m D M T signals, obtains the signal consistent with the local side clock.In the first possible implementation, according in a first aspect, before the local side sends m dmt signal by the n bar line synchronizations that are connected with the n user terminal to each user terminal, methods described also includes：The local side sends configured information to each user terminal, mark letter of the configured information comprising the pilot tone subset for sending the D M T signals, and predetermined coefficient, the predetermined coefficient is with sending the coefficient composition orthogonal matrix in the pilot tone subset of the DMT signals on each circuit.

In second of possible implementation, with reference to first aspect or the first possible implementation,

The m is the smallest natural number more than the n.

In the third possible implementation, with reference to first aspect or the first possible implementation or second of possible implementation, the local side sends m dmt signal by the n bar line synchronizations that are connected with the n user terminal to each user terminal, including：

Any n row of the local side respectively using orthogonal matrix W on the n bar circuits being connected with the n user terminal synchronously sends m dmt signal to each user terminal, wherein, the line number of the orthogonal matrix W is more than n, and the columns of the orthogonal matrix W is equal to m; Or,

Any n row of the local side respectively using orthogonal matrix W on the n bar circuits being connected with the n user terminal synchronously send m dmt signal to each user terminal, wherein, the columns of the orthogonal matrix W is more than n, and the line number of the orthogonal matrix W is equal to m.

In the 4th kind of possible implementation, with reference to the third possible implementation, described=2, the orthogonal matrix W is the square formation W of m ranks_m, the W ^ 々 recursive forms are：

1 1

1-1 wherein, and k is the natural number more than or equal to 1.Second aspect includes there is provided the method for another clock recovery, methods described：Each user terminal receives the m dmt signal that local side is sent, the m dmt signal from the local side by the n bar line synchronizations that are connected with n user terminal to the transmission of each user terminal；Wherein, every circuit sends the m dmt signal using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the dmt signal is sent on wherein any two lines road and constitutes orthogonal matrix, the user terminal number n is more than or equal to 2, and the m is more than the n;Each user terminal according to the m dmt signal received, obtains the signal consistent with the local side clock respectively.In the first possible implementation, according to second aspect, before each user terminal receives the m dmt signal that local side is sent, methods described also includes：Each user terminal receives the configured information that the local side is sent, mark letter of the configured information comprising the pilot tone subset for sending the D M T signals, I, and predetermined coefficient, the predetermined coefficient is with sending the coefficient composition orthogonal matrix in the pilot tone subset of the DMT signals on each circuit. In second of possible implementation, with reference to second aspect or the first possible implementation,

The m is the smallest natural number more than the n.

In the third possible implementation, with reference to second aspect or the first possible implementation or second of possible implementation, the m dmt signal is synchronously sent from any n rows of the local side respectively using orthogonal matrix W on the n bar circuits being connected with the n user terminal to each user terminal, wherein, the line number of the orthogonal matrix W is more than n, and the columns of the orthogonal matrix W is equal to m;

Or, synchronously m dmt signal is sent from any n row of the local side respectively using orthogonal matrix W on the n bar circuits being connected with the n user terminal to each user terminal, wherein, the columns of the orthogonal matrix W is more than n, and the line number of the orthogonal matrix W is equal to m.

In the 4th kind of possible implementation, with reference to the third possible implementation, described=2, the orthogonal matrix W is the square formation W of m ranks_m, the W ^ 々 recursive forms are：

1 1

1-1 wherein, and k is the natural number more than or equal to 1.In the 5th kind of possible implementation, with reference to the first possible implementation or second of possible implementation or the third possible implementation or the 4th kind of possible implementation, each described user terminal is respectively according to being received each user terminal_mIndividual dmt signal, obtains the signal consistent with the local side clock, including：The m dmt signal and the predetermined coefficient that each user terminal is received according to each user terminal obtain the phase difference of each user terminal and the local side；Each user terminal carries out clock alignment according to the phase difference, obtains the signal consistent with the local side clock.

The third aspect there is provided a kind of local side, including： Processor, for being respectively the n user terminal m DMT signal of generation being connected with the local side；

Transmitter, m dmt signal is sent for the n bar line synchronizations by being connected with the n user terminal to each user terminal；Wherein, every circuit sends the m dmt signal using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the dmt signal is sent on wherein any two lines road and constitutes orthogonal matrix, the user terminal number n is more than or equal to 2, and the m is more than the n;M dmt signal of the user terminal is used for the user terminal for receiving the m dmt signal according to the m D M T signals, obtains the signal consistent with the local side clock.

In the first possible implementation, according to the third aspect, the transmitter is additionally operable to：Before m dmt signal being sent in the n bar line synchronizations by being connected with the n user terminal to each user terminal, configured information is sent to each user terminal, the configured information includes the identification information and predetermined coefficient for the pilot tone subset for sending the dmt signal, and the predetermined coefficient constitutes orthogonal matrix with the coefficient sent on each circuit in the pilot tone subset of the dmt signal.

In second of possible implementation, with reference to the third aspect or the first possible implementation,

The m is the smallest natural number more than the n.

In the third possible implementation, with reference to the third aspect or the first possible implementation or second of possible implementation, the transmitter is additionally operable to：Any n rows on the n bar circuits being connected with the n user terminal respectively using orthogonal matrix W synchronously send m dmt signal to each user terminal, wherein, the line number of the orthogonal matrix W is more than n, and the columns of the orthogonal matrix W is equal to m;Or be used for, any n row respectively using orthogonal matrix W on the n bar circuits being connected with the n user terminal synchronously send m dmt signal to each user terminal, wherein, the columns of the orthogonal matrix W is more than n, and the line number of the orthogonal matrix W is equal to m.

In the 4th kind of possible implementation, with reference to the third possible implementation, described=orthogonal matrix W described in 2 is the square formation W of m ranks_m, the W ^ 々 recursion shapes Formula is：

1 1

1-1 wherein, and k is the natural number more than or equal to 1.

Fourth aspect there is provided a kind of user terminal, including：Receiver, the m dmt signal for receiving local side transmission, the m dmt signal from the local side by the n bar line synchronizations that are connected with n user terminal to the transmission of each user terminal；Wherein, every circuit sends the m dmt signal using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the dmt signal is sent on wherein any two lines road and constitutes orthogonal matrix, the user terminal number n is more than or equal to 2, and the m is more than the n;

Phaselocked loop, for the m dmt signal received according to the receiver, obtains the signal consistent with the local side clock.In the first possible implementation, according to fourth aspect,

The receiver is additionally operable to：Before the m dmt signal that local side is sent is received, receive the configured information that the local side is sent, mark letter of the configured information comprising the pilot tone subset for sending the dmt signal, and predetermined coefficient, the predetermined coefficient is with sending the coefficient composition orthogonal matrix in the pilot tone subset of the D M T signals on each circuit.

In second of possible implementation, with reference to fourth aspect or the first possible implementation,

The m is the smallest natural number more than the n.

In the third possible implementation, with reference to fourth aspect or the first possible implementation or second of possible implementation, the m dmt signal is synchronously sent from any n rows of the local side respectively using orthogonal matrix W on the n bar circuits being connected with the n user terminal to each user terminal, wherein The line number of the orthogonal matrix W is more than n, and the columns of the orthogonal matrix W is equal to m;Or, synchronously m dmt signal is sent from any n row of the local side respectively using orthogonal matrix W on the n bar circuits being connected with the n user terminal to each user terminal, wherein, the columns of the orthogonal matrix W is more than n, and the line number of the orthogonal matrix W is equal to m.

In the 4th kind of possible implementation, with reference to the third possible implementation, m=2^k, the orthogonal matrix W is the square formation W of m ranks_m, the W ^ 々 recursive forms are：

1 1

1-1 wherein, and k is the natural number more than or equal to 1.In the 5th kind of possible implementation, with reference to the first possible implementation or second of possible implementation or the third possible implementation or the 4th kind of possible implementation, the phaselocked loop is additionally operable to：

The m dmt signal and the predetermined coefficient that are received according to each user terminal obtain the phase difference of each user terminal and the local side；Clock alignment is carried out according to the phase difference, the signal consistent with the local side clock is obtained.There is provided a kind of system of clock recovery, including local side and user terminal in terms of 5th, wherein, the local side is used for, and respectively each user terminal generates m dmt signal；The local side sends m dmt signal by the n bar line synchronizations that are connected with the n user terminal to each user terminal；Wherein, every circuit sends the m dmt signal using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the dmt signal is sent on wherein any two lines road and constitutes orthogonal matrix, the user terminal number n is more than or equal to 2, and the m is more than the n;M dmt signal of the user terminal is used for the user terminal for receiving the m dmt signal according to the m dmt signal, obtains the signal consistent with the local side clock. The user terminal is used for：Receive the m dmt signal that local side is sent, the m DMT signals from the local side by the n bar line synchronizations that are connected with n user terminal to the transmission of each user terminal；Wherein, every circuit sends the m dmt signal using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the dmt signal is sent on wherein any two lines road and constitutes orthogonal matrix, the user terminal number n is more than or equal to 2, and the m is more than the n;Each user terminal according to the m dmt signal received, obtains the signal consistent with the local side clock respectively.A kind of clock recovery method provided in an embodiment of the present invention, equipment and system, local side is synchronous in same pilot tone to continuously transmit the corresponding m dmt signal of each user terminal respectively to n user terminal, and the corresponding m dmt signal of any two user terminal constitutes orthogonal matrix so that what each user terminal was received according to it respectively_mIndividual dmt signal carries out accurate clock alignment and obtains the signal consistent with local side clock.Overcome prior art and there is strong far-end interference due to spread spectrum, the SNR of clock synchronizing pilot signal for receiving user's termination is very low, and then cause user terminal from carrying out the defect of accurate calibration to clock.

Brief description of the drawings

The required accompanying drawing used in embodiment or description of the prior art is briefly described, apparently, drawings in the following description are only some embodiments of the present invention, for those of ordinary skill in the art, on the premise of not paying creative work, other accompanying drawings can also be obtained according to these accompanying drawings.Fig. 1 is a kind of structural representation of G.fast systems provided in an embodiment of the present invention；

Fig. 2 is a kind of structural representation of phaselocked loop provided in an embodiment of the present invention；Fig. 3 is a kind of flow chart of clock recovery method provided in an embodiment of the present invention；

Fig. 4 is the flow chart of another clock recovery method provided in an embodiment of the present invention；Fig. 5 is the flow chart of another clock recovery method provided in an embodiment of the present invention；

Fig. 6 is a kind of local side apparatus schematic diagram provided in an embodiment of the present invention；

Fig. 7 is a kind of ustomer premises access equipment schematic diagram provided in an embodiment of the present invention；Fig. 8 is another ustomer premises access equipment schematic diagram provided in an embodiment of the present invention； Fig. 9 is a kind of equipment schematic diagram applied to local side side provided in an embodiment of the present invention；Figure 10 is a kind of equipment schematic diagram applied to user side provided in an embodiment of the present invention.Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, it is clear that described embodiment is only a part of embodiment of the invention, rather than whole embodiments.Based on the embodiment in the present invention, the every other embodiment that those of ordinary skill in the art are obtained under the premise of creative work is not made belongs to the scope of protection of the invention.

The method of clock recovery provided in an embodiment of the present invention can apply to any synchronous time-division duplex (Synchronous Time Division Duplexing, abbreviation STDD), synchronous frequency division duplex (Synchronous Frequency Division Duplexing, abbreviation SFDD) DSL system, the present embodiment exemplified by Gfast this STDD system to illustrate.It is a kind of schematic diagram of Gfast systems referring to Fig. 1, including a local side, the local side can use one or more pilot tones by n bars n user terminal of connection for being connected with n user terminal, every circuit（Pilot tone) send dmt signal.In order to realize that user terminal obtains the signal consistent with local side, user terminal needs the clock with local side to be consistent, for example, user terminal can track the clock of local side by phaselocked loop, referring to Fig. 2, for a kind of structural representation of phaselocked loop, the phaselocked loop includes phase discriminator, loop filter and voltage controlled oscillator（Voltage-Controlled Oscillator, abbreviation VCO), the signal that user terminal is received from local side as phase discriminator input signal, when the clock of user terminal and local side is inconsistent, phaselocked loop passes through accurate phase demodulation, the phase difference of user terminal and local side is exported, then the signal consistent with local side is obtained by loop filtering and VCO.The embodiment of the present invention is illustrated from local side side and user side respectively, and the cooperation embodiment of the two is illustrated simultaneously, but this does not imply that the two must coordinate implementation, actually, when local side and user terminal are performed separately, it is also solved respectively in problem present on local side side, user side, when simply the two is used in combination, can obtain superior technique effect.

It is the clock recovery schematic flow sheet of local side side, as illustrated, may comprise steps of referring to Fig. 3：

301 :The local side being connected with n user terminal is respectively that each user terminal generates m dmt signal； 302:The local side sends m dmt signal by the n bar line synchronizations that are connected with the n user terminal to each user terminal；Wherein, every circuit sends the m dmt signal using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the D M T signals is sent on wherein any two lines road and constitutes orthogonal matrix, the user terminal number n is more than or equal to 2, and the m is more than the n;M dmt signal of the user terminal is used for the user terminal for receiving the m dmt signal according to the m D M T signals, obtains the signal consistent with the local side clock.

Exemplary, before local side sends m dmt signal by the n bar line synchronizations that are connected with n user terminal to each user terminal, methods described can also include：

Local side sends configured information to each user terminal, mark letter of the configured information comprising the pilot tone subset for sending the D M T signals, and predetermined coefficient, the predetermined coefficient is with sending the coefficient composition orthogonal matrix in the pilot tone subset of the DMT signals on each circuit.

Exemplary, m is the smallest natural number more than the n.Exemplary, local side sends m dmt signal by the n bar line synchronizations that are connected with n user terminal to each user terminal, can include：Any n row of the local side respectively using orthogonal matrix W on the n bar circuits being connected with n user terminal synchronously sends m dmt signal to each user terminal, wherein, orthogonal matrix W line number is more than n, and orthogonal matrix W columns is equal to m;Or,

Any n row of the local side respectively using orthogonal matrix W on the n bar circuits being connected with n user terminal synchronously send m dmt signal to each user terminal, wherein, orthogonal matrix W columns is more than n, and orthogonal matrix W line number is equal to m.Exemplary, m=2^k, orthogonal matrix W is the square formation W of m ranks_m, W_mRecursive form be： Wherein, k is the natural number more than or equal to 1.A kind of clock recovery method provided in an embodiment of the present invention, local side sends m dmt signal by the n bar line synchronizations that are connected with n user terminal to each user terminal；Every circuit sends m dmt signal using one or more pilot tones；The corresponding one or more pilot tones of n groups at least one identical pilot tone subset on n bar circuits；And the coefficient sent on any two lines road in the pilot tone subset of dmt signal constitutes orthogonal matrix so that user terminal can obtain the signal consistent with local side clock according to m dmt signal.Overcome prior art and there is strong far-end interference due to spread spectrum, the SNR of clock synchronizing pilot signal for receiving user's termination is very low, and then cause user terminal from carrying out the defect of accurate calibration to clock.It is the clock recovery schematic flow sheet of user side, as illustrated, may comprise steps of referring to Fig. 4：

401 :Each user terminal receives the m dmt signal that local side is sent, the m DMT signals from the local side by the n bar line synchronizations that are connected with n user terminal to the transmission of each user terminal；Wherein, every circuit sends the m dmt signal using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the dmt signal is sent on wherein any two lines road and constitutes orthogonal matrix, the user terminal number n is more than or equal to 2, and the m is more than the n;Exemplary, before the m dmt signal that local side is sent is received, methods described also includes：Each user terminal receives the configured information that local side is sent, the coefficient that the configured information is included in the identification information and predetermined coefficient for the pilot tone subset for sending DMT signals, pilot tone subset of the predetermined coefficient with sending dmt signal on each circuit constitutes orthogonal matrix.

Exemplary, m is the smallest natural number more than n.

Exemplary, each user terminal receives the m dmt signal that local side is sent, and can include：

M dmt signal is used just respectively by local side on the n bar circuits being connected with n user terminal Any n rows of matrix W are handed over synchronously to be sent to each user terminal, wherein, orthogonal matrix W line number is more than n, and orthogonal matrix W columns is equal to m;Or,

M dmt signal synchronously is sent to each user terminal from any n row of the local side respectively using orthogonal matrix W on the n bar circuits being connected with n user terminal, wherein, orthogonal matrix W columns is more than n, and orthogonal matrix W line number is equal to m.Exemplary, m=l^k, orthogonal matrix W is the square formation W of m ranks_m, W_mRecursive form be：

1 1

W,

1-1 wherein, and k is the natural number more than or equal to 1.

402:The m dmt signal that each user terminal is received according to each user terminal respectively, obtains the signal consistent with the local side clock.

Exemplary, the m DMT signal that each user terminal is received according to each user terminal respectively obtains the signal consistent with local side clock, can included：

M dmt signal and predetermined coefficient that each user terminal is received according to each user terminal obtain the phase difference of each user terminal and local side；Each user terminal carries out clock alignment according to the phase difference, obtains the signal consistent with local side clock.

A kind of clock recovery method provided in an embodiment of the present invention, each user terminal receives the m dmt signal that local side is sent, m dmt signal from local side by the n bar line synchronizations that are connected with n user terminal to the transmission of each user terminal；Every circuit sends m dmt signal using one or more pilot tones；The corresponding one or more pilot tones of n groups at least one identical pilot tone subset on n bar circuits；And the coefficient sent on any two lines road in the pilot tone subset of dmt signal constitutes orthogonal matrix, user terminal can carry out accurate clock alignment according to the m dmt signal received and obtain the signal consistent with local side clock.Prior art is overcome because frequency spectrum expands Open up and there is strong far-end interference, the SNR of clock synchronizing pilot signal for receiving user's termination is very low, and then cause user terminal from carrying out the defect of accurate calibration to clock.Above method embodiment is illustrated below by specific embodiment.Referring to Fig. 5, including：

S501 :The local side being connected with n user terminal is respectively that each user terminal generates m DMT signal；

S502:Local side sends configured information to n user terminal；

Exemplary, the configured information can send the identification information of the pilot tone of D M T signals comprising local side to user terminal, in order to which user terminal receives the dmt signal that local side is sent according to the identification information of the pilot tone, the identification information of the pilot tone can for pilot tone number information or it is other it is any can be with the information of unique mark pilot tone.Exemplary, the configured information can also include predetermined coefficient, and the predetermined coefficient can in advance be consulted to determine by local side and user terminal, and user terminal is then forwarded to after can also as needed being preset by local side.The present embodiment is to this without limiting.Exemplary, the predetermined coefficient is relevant with the coefficient of the pilot tone of dmt signal that local side is sent to user terminal, and the specific selection mode of predetermined coefficient will be described in detail in the present embodiment S503.

S503 :Local side sends m dmt signal by the n bar line synchronizations that are connected with n user terminal to each user terminal；

Exemplary, n bars circuit can be respectively adopted one or more pilot tones and send the corresponding one or more pilot tones of n groups at least one identical pilot tone subset on m DMT signal, n bar circuits；For example：When n is 3, if on first circuit dmt signal can be sent using pilot tone 1, pilot tone 2, pilot tone 3, dmt signal can be sent using pilot tone 1, pilot tone 5, pilot tone 6 on Article 2 circuit, dmt signal can be sent using pilot tone 1, pilot tone 4, pilot tone 5 on Article 3 circuit, then identical pilot tone subset includes pilot tone 1 on above-mentioned three-line.Exemplary, the pilot tone that n bars circuit can be respectively adopted in the pilot tone subset sends m dmt signal, and the coefficient sent on any two lines road in the pilot tone subset of dmt signal constitutes orthogonal matrix, user terminal number n is more than or equal to 2, m and is more than n.The coefficient of above-mentioned predetermined coefficient pilot tone subset corresponding with each circuit constitutes orthogonal matrix. Accordingly, the coefficient of the pilot tone subset of the corresponding m dmt signal of n bars circuit may be constructed n*m orthogonal matrix, and the coefficient and predetermined coefficient of the pilot tone subset of the corresponding m dmt signal of n bar circuits may be constructed（N+1) * m orthogonal matrix.Because the coefficient and predetermined coefficient of the pilot tone subset of the corresponding m dmt signal of n bar circuits may be constructed（N+1) * m orthogonal matrix, so, the coefficient and predetermined coefficient equationof structure of the m dmt signal pilot tone subset that user terminal can be received according to the user terminal, and then eliminate crosstalk, accurate phase demodulation.The principle is illustrated exemplified by being equal to 4, n equal to 3 below with m.

3 user terminals are referred to as the first user terminal by the present embodiment, and second user end, the 3rd user terminal, the signal that user terminal when having crosstalk is received are designated as r.When not having crosstalk, when the clock of user terminal and local side is inconsistent, the model for continuous 4 dmt signals that the user terminal is received is：

When there is crosstalk, when the clock of user terminal and local side is inconsistent, the model for continuous 4 dmt signals that the user terminal is received is：

[r_x , r₂ , r₃ , r₄ ] = [yz, yz² , γζ³ , γζ⁴ ] , (ζ = β ^θ) wherein, y is the signal received when the user terminal is consistent with local side clock, z.The phase difference of user terminal and local side when for without crosstalk.Z is the phase difference of user terminal and local side when having crosstalk, when can solve z=z., you can eliminate crosstalk and realize accurate phase demodulation.

Exemplary, local side is synchronous to the first user terminal, second user end, 3rd user terminal sends 4 dmt signals respectively, it should be noted that, the user terminal of the present embodiment first, second user end, the coefficient of the pilot tone subset of the respective 4 D M T signals of 3rd user terminal is not defined specifically, as long as meeting the first user terminal and second user end, second user end and the coefficient of the 3rd user terminal and the pilot tone subset of 4 dmt signals of the first user terminal and the 3rd user terminal respectively constitute orthogonal matrix, for example, the user terminal of the present embodiment first, second user end, the coefficient of the pilot tone subset of 4 dmt signals of the 3rd user terminal is respectively： 1、 -1、 1、 -1 ; 1、 1、 -1、 -1 ; 1、 -1、 -1、 1.Predetermined coefficient is designated as al, a2, a3, a4 in the present embodiment, in addition it should be noted that, the present embodiment is also limited for the selection of predetermined coefficient without specific, as long as orthogonal matrix can be respectively constituted with the coefficient of the first user terminal, second user end, the pilot tone subset of respective 4 dmt signals of the 3rd user terminal by meeting predetermined coefficient.For example, al=l, a2=l, a3=l, a4=l, i.e. predetermined coefficient are 1,1,1,1 in the present embodiment. Then the coefficient and predetermined coefficient of the pilot tone subset of 4 D M T signals of three user terminals can be with a a2 d 41111

1 -1 1 -1 I - 1 1 -1

Orthogonal matrix W is constituted, for example, W is w

1 1 -1 -1 I I - 1 -1

The cross-talk models of the user sides of ^ 23 1-1-1 1 1-1-1 1 are y=F (HX+Z), wherein, Y is the signal received when user terminal is consistent with local side clock, and X is the signal that local side is sent；Z is ambient noise, and F is frequency domain equalization coefficient, and H is crosstalk coefficient.Because Z is far below crosstalk noise, therefore Z is slightly disregarded in the present embodiment, then user side is doing FEQ (frequency domain equalizations）Cross-talk models before are=H.

Exemplary, 1 represents to send X in above-mentioned coefficient, and -1 represents transmission-x.4 dmt signals that then local side is sent to the first user terminal are respectively x ,-x, x ,-x;

4 dmt signals that local side is sent to second user end point+++Wei χ, χ ,-χ ,-χ;4 dmt signals that local side is sent to the 3rd user terminal are respectively χ ,-χ ,-χ, χ.

When user terminal clock is consistent with local side clock, the signal that three user terminals are received is respectively：

= H*W(2-A,:)x

X

Wherein, J^j j are respectively 4 signals that the first user terminal is continuously received when the first user terminal clock is consistent with local side clock, correspond respectively to 4 dmt signals χ ,-χ, χ ,-χ that local side is sent to the first user terminal; , ,₃ ², respectively second user end connects when second user end clock is consistent with local side clock 4 signals that continued access is received, correspond respectively to 4 dmt signals χ, χ ,-χ ,-χ that local side is sent to second user end;

, j₃ ³, 4 signals that respectively the 3rd user terminal is continuously received when the 3rd user terminal clock is consistent with local side clock correspond respectively to 4 dmt signals χ ,-χ ,-χ, X that local side is sent to the 3rd user terminal.

Without loss of generality, the present embodiment is illustrated by taking the first user terminal as an example, when the first user terminal clock and inconsistent local side clock, four signal rL that the first user terminal is received R is：Ri, ^, ^, ^ "： ^², ^² (1) by（1) following formula can equivalently be obtained: Wherein z=i.e.： Utilize the orthogonality of w matrixes

Especially, as can be seen from the above equation,

Therefore, + =0 a 2

+

a 3

+

a

4

+ y₄ = yy y₂ :))' = 0

o y, y₄Draw++ +=0 That is yl+yl+yl+(2) by（L) ' and（²) Shi Ke get

Namely lrz³ + 2r₂ ^lz² + 3r₃ ^lz + 4r₄ ^l = 0

Pass through（3) formula, is solved_z= z..Because（2) crosstalk signal has been eliminated in, thus the z degrees of accuracy asked greatly improve, and then has enabled the accurate phase demodulation of user terminal.

Pass through described above, when the coefficient that the signal sent in local side meets the pilot tone subset of m dmt signal of any two user terminal constitutes orthogonal matrix, the coefficient and predetermined coefficient equationof structure of the pilot tone subset for the m dmt signal that user terminal can be received according to the user terminal, the accurate phase demodulation of crosstalk progress can be eliminated by solving equation.

It is preferred that, local side can also send m dmt signal by the n bar line synchronizations that are connected with n user terminal directly according to the default matrix W for meeting condition in one or more pilot tones to each user terminal,

For example, any n row of the local side respectively using orthogonal matrix W on the n bar circuits being connected with n user terminal synchronously sends m dmt signal to each user terminal, wherein, orthogonal matrix W line number is more than n, and orthogonal matrix W columns is equal to m;Or, Any n row of the local side respectively using orthogonal matrix W on the n bar circuits being connected with n user terminal synchronously send m dmt signal to each user terminal, wherein, orthogonal matrix W columns is more than n, and orthogonal matrix W line number is equal to m.It is preferred that, when=2, orthogonal matrix W is can be with the square formation W of m ranks_m, W_mRecursive form be：

2" 2"-'

W

2" 2"

1 1

1-1 wherein, and k is the natural number more than or equal to 1.

For example, when n is equal to 3, m meets m>3, wherein w=2, therefore 2>", preferred k takes the smallest positive integral of the condition of satisfaction, therefore=2, m=4.Selected matrix ^ is：

1 1 1 1

I - 1 1 -1

Therefore₄

I I - 1 -1

1-1-1 1 is exemplary, and local side to n user terminal can send m dmt signal according to a kind of any of the above described rule, and the present embodiment is not limited to this, below the present embodiment simply introduce a kind of specific rules of local side transmission dmt signal.

For example, when n user terminal, any n row except the first row in addition to of the local side respectively using orthogonal matrix ^ in one or more pilot tones sends m dmt signal according to the following rules, wherein, the first behavior predetermined coefficient：

1st, the corresponding dmt signal of n bar circuits is alignd:

2nd, fixed signses point X；

3rd, to n user terminal numbering, number since 2, be followed successively by 2,3,

4th, j-th of user terminal sends dmt signal by ^ jth row, wherein 1 represents to send X, 1 represents transmission-X; 5th, same DMT moment, local side ensures that what is sent is ^ same row.

S504:The m dmt signal that each user terminal is received according to each user terminal obtains the phase difference of each user terminal and the local side；Exemplary, m dmt signal and the predetermined coefficient that user terminal can be received according to the user terminal obtain the phase difference of the user terminal and local side；

It can be seen from the explanation in S503, the coefficient and predetermined coefficient equationof structure of the pilot tone subset for the m DMT signal that user terminal can be received according to the user terminal： a\r_xz^m-¹ + a2r₂z^m-² + dhr^ + · · · + amr_m=0, so as to obtain the phase difference of the user terminal and local side.

For example, by taking one of user terminal as an example, user terminal can handle the letter received from local side, I, to obtain accurately phase difference following the next rules：

1st, since user terminal receive dmt signal arbitrarily including the dmt signal of above-mentioned pilot tone；

2nd, user terminal records continuous m dmt signal successively, be designated as r, r2, r ..., r_m ',

3rd, the predetermined coefficient equationof structure that user terminal is sent according to the m dmt signal and local side received, for example, the predetermined coefficient that local side is sent is al, a2, a3, during am, the equation of user terminal construction is： + a2r₂z^m-² + a3r₃z^m'³ + · · · + amr_m= 0；

4th, phase difference z=z of the user terminal and local side is obtained from above-mentioned equationof structure.= ^ ;

5th, using ^ as the phase discriminator in phaselocked loop output.

S505:Each user terminal carries out clock alignment according to the phase difference, obtains the signal consistent with the local side clock.Exemplary, the output for the phase discriminator that user terminal can be in phaselocked loop carries out clock alignment, so as to obtain the signal consistent with local side clock.

For example：By taking one of user terminal as an example, the information that the phase difference that user terminal can be according to S504 obtained by rule is received to user terminal carries out clock alignment：For example, on the basis of above-mentioned S504, above-mentioned rule can also include：

6th, the clock of user terminal is calibrated according to ^ by phaselocked loop；Obtain the m dmt signal consistent with local side clock；Exemplary, user terminal can periodically repeat above-mentioned regular 2 to 6, it is hereby achieved that the continuous signal consistent with local side clock.

It should be noted that when the user terminal that local side is connected is very more, local side can be to user terminal It is grouped, local side sends dmt signal to each group using the above method, the user terminal in each group can be caused to carry out accurate clock recovery respectively, and then obtain the signal consistent with local side.A kind of clock recovery method provided in an embodiment of the present invention, local side sends m dmt signal by the n bar line synchronizations that are connected with n user terminal to each user terminal；Every circuit sends m dmt signal using one or more pilot tones；The corresponding one or more pilot tones of n groups at least one identical pilot tone subset on n bar circuits；And the coefficient sent on any two lines road in the pilot tone subset of dmt signal constitutes orthogonal matrix so that user terminal can obtain the signal consistent with local side clock according to m dmt signal.Overcome prior art and there is strong far-end interference due to spread spectrum, the SNR of clock synchronizing pilot signal for receiving user's termination is very low, and then cause user terminal from carrying out the defect of accurate calibration to clock.

On the other hand, referring to Fig. 6, a kind of schematic device of the local side 60 provided for inventive embodiments, local side 60 provided in an embodiment of the present invention can apply to any synchronous time-division duplex (Synchronous Time Division Duplexing, abbreviation STDD), synchronous frequency division duplex (Synchronous Frequency Division Duplexing, abbreviation SFDD) DSL system, the present embodiment exemplified by Gfast this STDD system to illustrate.Referring to Fig. 1, for a kind of schematic diagram of Gfast systems, including a local side 60, the local side 60 can send dmt signal by n bars n user terminal of connection for being connected with n user terminal, every circuit using one or more pilot tones (ilot tone).As shown in fig. 6, the local side 60 includes：

Generation unit 601, for being respectively the n user terminal m dmt signal of generation being connected with the local side 60；Transmitting element 602, m dmt signal is sent for the n bar line synchronizations by being connected with the n user terminal to each user terminal；Wherein, every circuit sends the m dmt signal using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the dmt signal is sent on wherein any two lines road and constitutes orthogonal matrix, the user terminal number n is more than or equal to 2, and the m is more than the n;M dmt signal of the user terminal is used for the user terminal for receiving the m dmt signal according to the m dmt signal, obtains the signal consistent with the clock of local side 60.

Exemplary, transmitting element 602 can be also used for：By with the n user terminal phase Before sending m dmt signal to each user terminal to n bar line synchronizations even, configured information is sent to each user terminal, the configured information can send the identification information of the pilot tone of DMT signals comprising local side 60 to user terminal, in order to which user terminal receives the dmt signal that local side 60 is sent according to the identification information of the pilot tone, the identification information of the pilot tone can for pilot tone number information or it is other it is any can be with the information of unique mark pilot tone.

Exemplary, the configured information can also include predetermined coefficient, and the predetermined coefficient can in advance be consulted to determine by local side 60 and user terminal, and user terminal is then forwarded to after can also as needed being preset by local side.The present embodiment is to this without limiting.

Exemplary, the predetermined coefficient is relevant with the coefficient of the pilot tone subset of dmt signal that transmitting element 602 is sent to user terminal, for example, the coefficient sent on any two lines road in the pilot tone subset of dmt signal constitutes orthogonal matrix, user terminal number n is more than or equal to 2, m and is more than n.The coefficient of above-mentioned predetermined coefficient pilot tone subset corresponding with each circuit constitutes orthogonal matrix.

Accordingly, the coefficient of the pilot tone subset of the corresponding m dmt signal of η bars circuit may be constructed n*m orthogonal matrix, and the coefficient and predetermined coefficient of the pilot tone subset of the corresponding m dmt signal of n bar circuits may be constructed（N+1) * m orthogonal matrix.Because the coefficient and predetermined coefficient of the pilot tone subset of the corresponding m dmt signal of n bar circuits may be constructed（N+1) * m orthogonal matrix, so, the coefficient and predetermined coefficient equationof structure of the pilot tone subset for the m dmt signal that user terminal receives according to the user terminal can be caused, and then eliminate crosstalk, accurate phase demodulation.The principle is illustrated exemplified by being equal to 4, n equal to 3 below with m.

3 user terminals are referred to as the first user terminal by the present embodiment, and second user end, the 3rd user terminal, the signal that user terminal when having crosstalk is received are designated as r.When not having crosstalk, when the clock of user terminal and local side 60 is inconsistent, the model for continuous 4 dmt signals that the user terminal is received is：

i , r₂ , r₃ , r₄ ] = [yz₀ , , yz₀ ⁴ ] , (ζ₀ = β^ιθ )

When there is crosstalk, when the clock of user terminal and local side 60 is inconsistent, the model for continuous 4 dmt signals that the user terminal is received is：

\r_x , r₂ , r₃ , r₄ ] = [yz, yz² , yz³ , yz⁴ ] , (z = e^l°) wherein, y is the signal received when the user terminal is consistent with the clock of local side 60, z.Not go here and there The phase difference of user terminal and local side 60 when disturbing.Z is the phase difference of user terminal and local side 60 when having crosstalk, when can solve z=z., you can eliminate crosstalk and realize accurate phase demodulation.

Exemplary, local side 60 is synchronous to the first user terminal, second user end, 3rd user terminal sends 4 dmt signals respectively, it should be noted that, the user terminal of the present embodiment first, second user end, the coefficient of the pilot tone subset of the respective 4 D M T signals of 3rd user terminal is not defined specifically, as long as meeting the first user terminal and second user end, second user end and the coefficient of the 3rd user terminal and the pilot tone subset of 4 dmt signals of the first user terminal and the 3rd user terminal respectively constitute orthogonal matrix, for example, the user terminal of the present embodiment first, second user end, the coefficient of the pilot tone subset of 4 dmt signals of the 3rd user terminal is respectively： 1、 -1、 1、 -1 ; 1、 1、 -1、 -1 ; 1、 -1、 -1、 1.Predetermined coefficient is designated as al, a2, a3, a4 in the present embodiment, in addition it should be noted that, the present embodiment is also limited for the selection of predetermined coefficient without specific, as long as orthogonal matrix can be respectively constituted with the coefficient of the first user terminal, second user end, the pilot tone subset of respective 4 dmt signals of the 3rd user terminal by meeting predetermined coefficient.For example, al=l, a2=l, a3=l, a4=l, i.e. predetermined coefficient are 1,1,1,1 in the present embodiment.

Then the coefficient and predetermined coefficient of the pilot tone subset of 4 dmt signals of three user terminals may be constructed orthogonal matrix W, for example, W

The cross-talk models of user side are=F (HX+Z), wherein, Y is the signal received when user terminal is consistent with the clock of local side 60, and X is the signal that local side 60 is sent；Z is ambient noise, and F is frequency domain equalization coefficient, and H is crosstalk coefficient.Because Z is far below crosstalk noise, therefore Z is slightly disregarded in the present embodiment, then user side is doing FEQ (frequency domain equalizations）Cross-talk models before are=H.

Exemplary, 1 represents to send X in above-mentioned coefficient, and -1 represents transmission-x.4 dmt signals that then local side 60 is sent to the first user terminal are respectively χ ,-χ, χ ,-χ;

4 dmt signals that local side 60 is sent to second user end are respectively χ, χ ,-χ ,-χ;

4 dmt signals that local side 60 is sent to the 3rd user terminal are respectively χ ,-χ ,-χ, χ.

When user terminal clock is consistent with the clock of local side 60, the signal that three user terminals are received is respectively： = H*W(2-A,:)x Wherein, 4 signals that respectively the first user terminal is continuously received when the first user terminal clock is consistent with the clock of local side 60, correspond respectively to 4 dmt signals χ ,-χ, χ ,-χ that local side 60 is sent to the first user terminal; ,₂ ²,J₃ ²,J₄ ²4 signals that respectively second user end is continuously received when second user end clock is consistent with the clock of local side 60, correspond respectively to 4 dmt signals χ, χ ,-χ ,-χ that local side 60 is sent to second user end; ,j j₃ ³,j₄ ³4 signals that respectively the 3rd user terminal is continuously received when the 3rd user terminal clock is consistent with the clock of local side 60, correspond respectively to 4 dmt signals χ ,-χ ,-χ, χ that local side 60 is sent to the 3rd user terminal.

Without loss of generality, the present embodiment is illustrated by taking the first user terminal as an example, when the first user terminal clock and the inconsistent clock of local side 60, four signal 44^ that the first user terminal is received, and 4 are：^, ^, ^ ,], wherein ζ=(1) by（1) following formula can equivalently be obtained：

^ΑΐΓ' I- [ « 4 ]

( 1 )

+

a

2

Utilize the orthogonality of W squares+battle array

a

3

+

a

4

Especially, as can be seen from the above equation,

W(2:4,:)*(W(l,:)) therefore,

W(2:4,:)*(W(l,:))

+ + + ] = [ ή ή

That is yl+y2+yl+A=o (2) by（1), and（2) Shi Ke get

Namely η ζ³ + =0 i.e. i^₊4+4+4=0, that is, r^+^V+r^+r^O (3) Pass through（3) formula, is solved_z= z..Because（2) crosstalk signal has been eliminated in, thus the z degrees of accuracy asked greatly improve, and then has enabled the accurate phase demodulation of user terminal.

Pass through described above, when the coefficient that the signal sent in local side 60 meets the ^2 pilot tone subsets of m D M T signal of any two user terminal constitutes orthogonal matrix, the coefficient and predetermined coefficient equationof structure of the pilot tone subset for the m dmt signal that user terminal can be received according to the user terminal, the accurate phase demodulation of crosstalk progress can be eliminated by solving equation.

It is preferred that, local side 60 can also send m dmt signal by the n bar line synchronizations that are connected with n user terminal directly according to the default matrix W for meeting condition in one or more pilot tones to each user terminal,

For example, any n rows on the n bar circuits that local side 60 is connected with n user terminal respectively using orthogonal matrix W synchronously send m dmt signal to each user terminal, wherein, orthogonal matrix W line number is more than n, and orthogonal matrix W columns is equal to m;Or,

Any n row on the n bar circuits that local side 60 is connected with n user terminal respectively using orthogonal matrix W synchronously send m dmt signal to each user terminal, wherein, orthogonal matrix W columns is more than n, and orthogonal matrix W line number is equal to m.It is preferred that, when=2, orthogonal matrix W is can be with the square formation W of m ranks_m, W_mRecursive form be：

2" 2"

W

2" 2"

1 1

1-1 wherein, and k is the natural number more than or equal to 1.

For example, when n is equal to 3, m meets m>3, wherein w=2, therefore 2>", preferred k takes the smallest positive integral of the condition of satisfaction, therefore=2, m=4.Selected matrix ^ is：

1 1

According to₇

1 -1 1 1 1 1

m ϋ 1 -1 1 -1

Therefore₄ = 。

4 1 1 -1 -1

1-1-1 1 is exemplary, local side 60 can be according to any of the above described a kind of regular to η user terminal m dmt signal of transmission, the present embodiment is not limited to this, below the present embodiment simply introduce the specific rules that a kind of local side 60 sends dmt signal.

For example, when n user terminal, any n row except the first row in addition to of the local side 60 respectively using orthogonal matrix ^ in one or more pilot tones sends m dmt signal according to the following rules, wherein, ^ the first behavior predetermined coefficient：

1st, the corresponding dmt signal of n bar circuits is alignd；

2nd, fixed signses point X；

3rd, to n user terminal numbering, number since 2, be followed successively by 2,3,

4th, j-th of user terminal sends dmt signal by ^ jth row, wherein 1 represents to send X, -1 represents transmission-X;

5th, same DMT moment, local side 60 ensures that what is sent is ^ same row.

It should be noted that, when the user terminal that local side 60 is connected is very more, local side 60 can be grouped to user terminal, local side 60 sends dmt signal to each group using the above method, the user terminal in each group can be caused to carry out accurate clock recovery respectively, and then obtain the signal with local side 60-cause.

A kind of local side 60 provided in an embodiment of the present invention, local side 60 sends m dmt signal by the n bar line synchronizations that are connected with n user terminal to each user terminal；Every circuit sends m dmt signal using one or more pilot tones；The corresponding one or more pilot tones of n groups at least one identical pilot tone subset on n bar circuits；And the coefficient sent on any two lines road in the pilot tone subset of DMT signals constitutes orthogonal matrix so that user terminal can obtain the signal consistent with the clock of local side 60 according to m dmt signal.Overcome prior art and there is strong far-end interference due to spread spectrum, the SNR of clock synchronizing pilot signal for receiving user's termination is very low, and then cause user terminal from carrying out the defect of accurate calibration to clock.It is a kind of schematic device of user terminal 70 provided in an embodiment of the present invention referring to Fig. 7, user terminal 70 provided in an embodiment of the present invention can apply to any synchronous time-division duplex（Synchronous Time Division Duplexing, abbreviation STDD), synchronous frequency division duplex（Synchronous Frequency Division Duplexing, abbreviation SFDD) DSL system, the present embodiment with Illustrated exemplified by this STDD system of G.fast.It is a kind of schematic diagram of G.fast systems referring to Fig. 1, including a local side, the local side can use one or more pilot tones by n user terminal of n bars connection 70 for being connected with n user terminal 70, every circuit（Pilot tone) send dmt signal.As Figure 7-8, the user terminal 70 can include：

Receiving unit 701:The m dmt signal for receiving local side transmission, the m DMT signals are sent from the local side by the n bar line synchronizations that are connected with n user terminal 70 to each user terminal 70；Wherein, every circuit sends the m DMT signals using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the dmt signal is sent on wherein any two lines road and constitutes orthogonal matrix, the number n of user terminal 70 is more than or equal to 2, and the m is more than the n;Exemplary, receiving unit 701 can be also used for：Before the m DMT signal that local side is sent is received, receive the configured information that local side is sent, the configured information can send the identification information of the pilot tone of dmt signal comprising local side to user terminal 70, in order to which user terminal 70 receives the D M T signals that local side is sent according to the identification information of the pilot tone, the identification information of the pilot tone can for pilot tone number information or it is other it is any can be with the information of unique mark pilot tone.

Exemplary, the configured information can also include predetermined coefficient, and the predetermined coefficient can in advance be consulted to determine by local side and user terminal 70, and user terminal 70 is then forwarded to after can also as needed being preset by local side.The present embodiment is to this without limiting.

Exemplary, the predetermined coefficient is relevant with the coefficient of the pilot tone subset of dmt signal that local side is sent to user terminal 70, for example, the coefficient sent on any two lines road in the pilot tone subset of dmt signal constitutes orthogonal matrix, user terminal number n is more than or equal to 2, m and is more than n.The coefficient of above-mentioned predetermined coefficient pilot tone subset corresponding with each circuit constitutes orthogonal matrix.Above-mentioned predetermined coefficient and the coefficient of the pilot tone subset of m dmt signal of each user terminal 70 constitute orthogonal matrix.For example, predetermined coefficient can be designated as al, a2, a3 ..., am.

Accordingly, the coefficient of the pilot tone subset of the corresponding m dmt signal of η bars circuit may be constructed n*m orthogonal matrix, and the coefficient and predetermined coefficient of the pilot tone subset of the corresponding m dmt signal of n bar circuits may be constructed（N+1) * m orthogonal matrix.

Exemplary, m is the smallest natural number more than n. Exemplary, m dmt signal is synchronously sent from any n rows of the local side respectively using orthogonal matrix W on the n bar circuits being connected with n user terminal 70 to each user terminal 70, wherein, orthogonal matrix W line number is more than n, and orthogonal matrix W columns is equal to m;

Or, synchronously m dmt signal is sent from any n row of the local side respectively using orthogonal matrix W on the n bar circuits being connected with n user terminal 70 to each user terminal 70, wherein, orthogonal matrix W columns is more than n, and orthogonal matrix W line number is equal to m.Exemplary, m=l^k, orthogonal matrix W is the square formation W of m ranks_m, W_mRecursive form be：

1 1

1-1 wherein, and k is the natural number more than or equal to 1.

Acquiring unit 702:For the m dmt signal received according to each user terminal 70, the signal consistent with the local side clock is obtained.

Exemplary, acquiring unit 702 can include：

Phase difference module 7001, m dmt signal and predetermined coefficient for being received according to each user terminal 70 obtain the phase difference of each user terminal 70 and local side；Exemplary, the coefficient and the predetermined coefficient of the pilot tone subset for the m DMT signal that phase difference module 7001 can be received according to receiving unit 701 obtain the phase difference of the user terminal and local side；

Principle explanation in claim to a method S503 is understood, when the coefficient that the signal sent in local side meets the pilot tone subset of m dmt signal of any two user terminal 70 constitutes orthogonal matrix, the signal of any user terminal 70 reception meet a r_xz^m-^x + a2r₂z^m-² + ir^ + · · · + amr_m=0, so, the coefficient and predetermined coefficient equationof structure of the pilot tone subset for the m dmt signal that phase difference module 7001 can be received according to the user terminal 70 can eliminate the accurate phase demodulation of crosstalk progress by solving equation.

For example, phase difference module 7001 can occupy the coefficient and predetermined coefficient equationof structure of the pilot tone subset for the m dmt signal that the user terminal 70 is received： a\r_xz^m-¹ + air -¹ + a3rf + ··· + amr_m=0, so as to obtain the phase difference of the user terminal 70 and local side.For example, user terminal 70 can handle the information from local side reception following the next rules to obtain accurately phase difference：

1st, since user terminal 70 receive dmt signal arbitrarily including the dmt signal of above-mentioned pilot tone；

2nd, user terminal 70 records continuous m dmt signal successively, is designated as rl, r₂, r3 ..., r；

3rd, the predetermined coefficient equationof structure that user terminal 70 is sent according to the m dmt signal and local side received, for example, the predetermined coefficient that local side is sent is al, a2, a3, during am, the equation of user terminal construction is： a\rz^m' + a2r₂z^m-² + a3r₃z^m-³ + · · · + amr_m= 0；

4th, user terminal 70 obtains phase difference z=z of the user terminal and local side from above-mentioned equationof structure.= ^ ;

5th, phase difference module 7001 using ^ as phase difference module 7001 output.Clock alignment module 7002, clock alignment is carried out according to the phase difference, obtains the signal consistent with the local side clock.

Exemplary, clock alignment module 7002 can carry out clock alignment according to the output of phase difference module 7001, so as to obtain the signal consistent with local side clock.

For example：Clock alignment module 7002 can carry out clock alignment according to the information that the phase difference obtained by above-mentioned rule is received to user terminal：For example, above-mentioned rule can also include：

6th, the clock of user terminal 70 is calibrated according to ^ by clock alignment module 7002；Obtain the m dmt signal consistent with local side clock；Exemplary, user terminal 70 can periodically repeat above-mentioned regular 2 to 6, it is hereby achieved that the continuous signal consistent with local side clock.It should be noted that, when the user terminal 70 that local side is connected is very more, local side can be grouped to user terminal 70, local side sends dmt signal to each group using the above method, the user terminal 70 in each group can be caused to carry out accurate clock recovery respectively, and then obtain the signal consistent with local side.

A kind of user terminal 70 provided in an embodiment of the present invention, each user terminal 70 receives the m dmt signal that local side is sent, and m dmt signal is sent from local side by the n bar line synchronizations that are connected with n user terminal 70 to each user terminal 70；Every circuit sends m dmt signal using one or more pilot tones；The corresponding one or more pilot tones of n groups at least one identical pilot tone subset on n bar circuits；And the pilot tone of dmt signal is sent on any two lines road Coefficient in subset constitutes orthogonal matrix, and user terminal 70 can carry out accurate clock alignment according to the m dmt signal received and obtain the signal consistent with local side clock.Overcome prior art and there is strong far-end interference due to spread spectrum, make the SNR for the clock synchronizing pilot signal that user terminal 70 receives very low, and then cause user terminal 70 from carrying out the defect of accurate calibration to clock.

On the other hand, referring to Fig. 9, a kind of schematic device of the local side 60 provided for inventive embodiments, local side 60 provided in an embodiment of the present invention can apply to any synchronous time-division duplex (Synchronous Time Division Duplexing, abbreviation STDD), synchronous frequency division duplex (Synchronous Frequency Division Duplexing, abbreviation SFDD) DSL system, the present embodiment exemplified by Gfast this STDD system to illustrate.Referring to Fig. 1, for a kind of schematic diagram of Gfast systems, including a local side 60, the local side 60 can send dmt signal by n bars n user terminal of connection for being connected with n user terminal, every circuit using one or more pilot tones (ilot tone).As shown in figure 9, the local side 60 includes：

Processor 901, for being respectively the n user terminal m dmt signal of generation being connected with the local side 60；

Transmitter 902, m dmt signal is sent for the n bar line synchronizations by being connected with the n user terminal to each user terminal；Wherein, every circuit sends the m dmt signal using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the dmt signal is sent on wherein any two lines road and constitutes orthogonal matrix, the user terminal number n is more than or equal to 2, and the m is more than the n;M dmt signal of the user terminal is used for the user terminal for receiving the m dmt signal according to the m dmt signal, obtains the signal consistent with the clock of local side 60.

Exemplary, transmitter 902 can be also used for：Before m dmt signal being sent in the n bar line synchronizations by being connected with the n user terminal to each user terminal, configured information is sent to each user terminal, the configured information can send the identification information of the pilot tone of DMT signals comprising local side 60 to user terminal, in order to which user terminal receives the dmt signal that local side 60 is sent according to the identification information of the pilot tone, the identification information of the pilot tone can for pilot tone number information or it is other it is any can be with the information of unique mark pilot tone.

Exemplary, the configured information can also include predetermined coefficient, and the predetermined coefficient can be by office End 60 and user terminal consult determination in advance, and user terminal is then forwarded to after can also as needed being preset by local side.The present embodiment is to this without limiting.

Exemplary, the predetermined coefficient is relevant with the coefficient of the pilot tone subset for the dmt signal that transmitter 902 is sent to user terminal, for example, the coefficient sent on any two lines road in the pilot tone subset of dmt signal constitutes orthogonal matrix, user terminal number n is more than or equal to 2, m and is more than n.The coefficient of above-mentioned predetermined coefficient pilot tone subset corresponding with each circuit constitutes orthogonal matrix.

Accordingly, the coefficient of the pilot tone subset of the corresponding m dmt signal of η bars circuit may be constructed n*m orthogonal matrix, and the coefficient and predetermined coefficient of the pilot tone subset of the corresponding m dmt signal of n bar circuits may be constructed（N+1) * m orthogonal matrix.Because the coefficient and predetermined coefficient of the pilot tone subset of the corresponding m dmt signal of n bar circuits may be constructed（N+1) * m orthogonal matrix, so, the coefficient and predetermined coefficient equationof structure for the m dmt signal pilot tone subset that user terminal receives according to the user terminal can be caused, and then eliminate crosstalk, accurate phase demodulation.The principle is illustrated exemplified by being equal to 4, n equal to 3 below with m.

3 user terminals are referred to as the first user terminal by the present embodiment, and second user end, the 3rd user terminal, the signal that user terminal when having crosstalk is received are designated as r.When not having crosstalk, when the clock of user terminal and local side 60 is inconsistent, the model for continuous 4 dmt signals that the user terminal is received is：

, r₂ , r₃ , r₄ ] = [yz₀ , ] , (z₀ = e ^e) when there is crosstalk, when the clock of user terminal and local side 60 is inconsistent, the model for continuous 4 dmt signals that the user terminal is received is：

i , r₂ , r₃ , r₄ ] = [yz, yz² , yz³ , yz⁴ ] , (z = e'^e) wherein, y is the signal received when the user terminal is consistent with the clock of local side 60, z.The phase difference of user terminal and local side 60 when for without crosstalk.Z is the phase difference of user terminal and local side 60 when having crosstalk, when can solve z=z., you can eliminate crosstalk and realize accurate phase demodulation.

Exemplary, local side 60 is synchronous to send 4 dmt signals respectively to the first user terminal, second user end, the 3rd user terminal, it should be noted that, the user terminal of the present embodiment first, second user end, the coefficient of the pilot tone subset of the respective 4 D M T signals of the 3rd user terminal are not defined specifically, as long as meeting the first user terminal and second user end, second user end and the 3rd user terminal and first The coefficient of the pilot tone subset of 4 dmt signals of the user terminals of user terminal ρ 23 and the 3rd respectively constitutes orthogonal matrix, for example, the user terminal of the present embodiment first, second user end, the coefficient of the pilot tone subset of 4 dmt signals of the 3rd user terminal are respectively： 1、 -1、 1、 -1; 1、 1、 -1、 -1; 1、 -1、 -1、 1.Predetermined coefficient is designated as al, a2, a3, a4 in the present embodiment, in addition it should be noted that, the present embodiment is also limited for the selection of predetermined coefficient without specific, as long as orthogonal matrix can be respectively constituted with the coefficient of the first user terminal, second user end, the pilot tone subset of respective 4 dmt signals of the 3rd user terminal by meeting predetermined coefficient.For example, al=l, a2=l, a3=l, a4=l, i.e. predetermined coefficient are 1,1,1,1 in the present embodiment.

Then the coefficient and predetermined coefficient of the pilot tone subset of 4 dmt signals of three user terminals can be with a a2 b 41111

1 -1 1 -1 I - 1 1 -1

Orthogonal matrix W is constituted, for example, W is w

1 1 -1 -1 I I - 1 -1

The cross-talk models of 1-1-1 1 1-1-1 1 user side are F=F (H+Z), wherein, Y is the signal received when user terminal is consistent with the clock of local side 60, and X is the signal that local side 60 is sent；Z is ambient noise, and F is frequency domain equalization coefficient, and H is crosstalk coefficient.Because Z is far below crosstalk noise, therefore Z is slightly disregarded in the present embodiment, then user side is doing FEQ (frequency domain equalizations）Cross-talk models before are F=H.

Exemplary, 1 represents to send X in above-mentioned coefficient, and -1 represents transmission-x.4 dmt signals that then local side 60 is sent to the first user terminal are respectively χ ,-χ, χ ,-χ;

4 dmt signals that local side 60 is sent to second user end are respectively χ, χ ,-χ ,-χ;

4 dmt signals that local side 60 is sent to the 3rd user terminal are respectively χ ,-χ ,-χ, χ.

When user terminal clock is consistent with the clock of local side 60, the signal difference that three user terminals are received

H*W(2-A,:)x

] _{ +h + h_l3 -h +h_v

- ⁺

—h₃ h_yWherein, ^, 4 signals that respectively the first user terminal is continuously received when the first user terminal clock is consistent with the clock of local side 60 correspond respectively to 4 dmt signals χ ,-χ, χ ,-χ that local side 60 is sent to the first user terminal;

y_i ²,j₂ ²,j₃ ², 4 signals that respectively second user end is continuously received when second user end clock is consistent with the clock of local side 60 correspond respectively to 4 dmt signals χ, χ ,-χ ,-χ that local side 60 is sent to second user end;

+ + +

y_i ³,j j₃ ³,j₄ ³4 signals that respectively the 3rd user terminal is continuously received when the 3rd user terminal clock is consistent with the clock of local side 60, correspond respectively to 4 dmt signals χ ,-χ ,-χ, χ that local side 60 is sent to the 3rd user terminal.

Without loss of generality, the present embodiment is illustrated by taking the first user terminal as an example, when the first user terminal clock and the inconsistent clock of local side 60, and four signal Ar^A that the first user terminal is received are： r{,r₂,r₃,r₄ \ = \ |, wherein by（1) following formula can equivalently be obtained： Wherein_Z=e is " i.e.：I i i i y y y A ^ wherein (1) utilize the orthogonality of w matrixes

Especially, as can be seen from the above equation, (2:4,:)* ,:))

Therefore,

al

a2

a\y_x + a2y₂ + a3y₃ + a4y₄ [h, , ₂ h_l3 W{2: 4, :) * (W( :))' = 0 a3

a4

h_l3W{2: 4, :) * (W( :)) '=0 draw That is yl+y₂+yl + (2) by（L) ' and（²) Shi Ke get

(3) pass through（3) formula, is solved_ζ= ζ..Because（2) crosstalk signal has been eliminated in, thus the ζ degrees of accuracy asked greatly improve, and then has enabled the accurate phase demodulation of user terminal.

By described above, the signal sent in local side 60 meets any two user terminal correspondence M dmt signal pilot tone subset coefficient constitute orthogonal matrix when, the coefficient and predetermined coefficient equationof structure of the pilot tone subset for the m dmt signal that user terminal can be received according to the user terminal, the accurate phase demodulation of crosstalk progress can be eliminated by solving equation.

It is preferred that, local side 60 can also send m dmt signal by the n bar line synchronizations that are connected with n user terminal directly according to the default matrix W for meeting condition in one or more pilot tones to each user terminal,

For example, any n rows on the n bar circuits that local side 60 is connected with n user terminal respectively using orthogonal matrix W synchronously send m dmt signal to each user terminal, wherein, orthogonal matrix W line number is more than n, and orthogonal matrix W columns is equal to m;Or,

Any n row on the n bar circuits that local side 60 is connected with n user terminal respectively using orthogonal matrix W synchronously send m dmt signal to each user terminal, wherein, orthogonal matrix W columns is more than n, and orthogonal matrix W line number is equal to m.It is preferred that, when=2, orthogonal matrix W is can be with the square formation W of m ranks_m, W_mRecursive form be：

2" 2"-'

W

2" 2"

1 1

1-1 wherein, and k is the natural number more than or equal to 1.For example, when n is equal to 3, m meets m>3, wherein=2, therefore 2>Μ, preferred k take the smallest positive integral of the condition of satisfaction, therefore=2, m=4.Selected matrix ^ is：

1 1 1 1

I - 1 1 -1

Therefore ^

I I - 1 -1

1 -1 -1 1 Exemplary, local side 60 to η user terminal can send m dmt signal according to a kind of any of the above described rule, and the present embodiment is not limited to this, below the present embodiment simply introduce a kind of specific rules of the transmission of local side 60 dmt signal.

For example, when n user terminal, any n row except the first row in addition to of the local side 60 respectively using orthogonal matrix ^ in one or more pilot tones sends m dmt signal according to the following rules, wherein, the first behavior predetermined coefficient：

1st, the corresponding dmt signal of n bar circuits is alignd；

2nd, fixed signses point X；

3rd, to n user terminal numbering, number since 2, be followed successively by 2,3,

4th, j-th of user terminal by jth row send dmt signal, wherein 1 represents to send X, -1 represents transmission-X;

5th, the same DMT moment, local side 60 ensure send be_mSame row.

It should be noted that, when the user terminal that local side 60 is connected is very more, local side 60 can be grouped to user terminal, local side 60 sends dmt signal to each group using the above method, the user terminal in each group can be caused to carry out accurate clock recovery respectively, and then obtain the signal with local side 60-cause.

A kind of local side 60 provided in an embodiment of the present invention, local side 60 sends m dmt signal by the n bar line synchronizations that are connected with n user terminal to each user terminal；Every circuit sends m dmt signal using one or more pilot tones；The corresponding one or more pilot tones of n groups at least one identical pilot tone subset on n bar circuits；And the coefficient sent on any two lines road in the pilot tone subset of dmt signal constitutes orthogonal matrix so that user terminal can obtain the signal consistent with the clock of local side 60 according to m DMT signal.Overcome prior art and there is strong far-end interference due to spread spectrum, the SNR of clock synchronizing pilot signal for receiving user's termination is very low, and then cause user terminal from carrying out the defect of accurate calibration to clock.

Referring to Figure 10, for the schematic device of another user terminal 70 provided in an embodiment of the present invention, user terminal 70 provided in an embodiment of the present invention can apply to any synchronous time-division duplex (Synchronous Time Division Duplexing, abbreviation STDD), synchronous frequency division duplex (Synchronous Frequency Division Duplexing, abbreviation SFDD) DSL system, the present embodiment exemplified by Gfast this STDD system to illustrate.It is a kind of schematic diagram of Gfast systems referring to Fig. 1, including a local side, the local side can use one or more pilot tones by n user terminal of n bars connection 70 for being connected with n user terminal 70, every circuit（pilot Tone dmt signal) is sent.

As shown in Figure 10, the user terminal 70 can include：

Receiver 1001:The m dmt signal for receiving local side transmission, the m DMT signals are sent from the local side by the n bar line synchronizations that are connected with n user terminal 70 to each user terminal 70；Wherein, every circuit sends the m DMT signals using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the dmt signal is sent on wherein any two lines road and constitutes orthogonal matrix, the number n of user terminal 70 is more than or equal to 2, and the m is more than the n;Exemplary, receiver 1001 can be also used for：Before the m DMT signal that local side is sent is received, receive the configured information that local side is sent, the configured information can send the identification information of the pilot tone of dmt signal comprising local side to user terminal 70, in order to which user terminal 70 receives the D M T signals that local side is sent according to the identification information of the pilot tone, the identification information of the pilot tone can for pilot tone number information or it is other it is any can be with the information of unique mark pilot tone.

Exemplary, the configured information can also include predetermined coefficient, and the predetermined coefficient can in advance be consulted to determine by local side and user terminal 70, and user terminal is then forwarded to after can also as needed being preset by local side.The present embodiment is to this without limiting.

Exemplary, the predetermined coefficient is relevant with the coefficient of the pilot tone subset of dmt signal that local side is sent to user terminal 70, for example, the coefficient sent on any two lines road in the pilot tone subset of dmt signal constitutes orthogonal matrix, user terminal number n is more than or equal to 2, m and is more than n.The coefficient of above-mentioned predetermined coefficient pilot tone subset corresponding with each circuit constitutes orthogonal matrix.The coefficient of the pilot tone subset of above-mentioned predetermined coefficient m dmt signal corresponding with each user terminal 70 constitutes orthogonal matrix.For example, predetermined coefficient can be designated as al, a2, a3 ..., am.

Accordingly, the coefficient of the pilot tone subset of the corresponding m dmt signal of η bars circuit may be constructed n*m orthogonal matrix, and the coefficient and predetermined coefficient of the corresponding m dmt signal of n bar circuits may be constructed（N+1) * m orthogonal matrix.

Exemplary, m is the smallest natural number more than n.

Exemplary, m dmt signal is synchronously sent from any n rows of the local side respectively using orthogonal matrix W on the n bar circuits being connected with n user terminal 70 to each user terminal 70, wherein, orthogonal matrix W line number is more than n, and orthogonal matrix W columns is equal to m; Or, synchronously m dmt signal is sent from any n row of the local side respectively using orthogonal matrix W on the n bar circuits being connected with n user terminal 70 to each user terminal 70, wherein, orthogonal matrix W columns is more than n, and orthogonal matrix W line number is equal to m.Exemplary, m=t, orthogonal matrix W is the square formation W of m ranks_m, W_mRecursive form be：

1 1

1-1 wherein, and k is the natural number more than or equal to 1.

Phaselocked loop 1002:For the m dmt signal received according to each user terminal 70, the signal consistent with the local side clock is obtained.Exemplary, user terminal 70 is in order to obtain the signal consistent with local side, the clock with local side is needed to be consistent, for example, user terminal 70 can track the clock of local side by phaselocked loop 1002, referring to Fig. 2, for a kind of structural representation of phaselocked loop 1002, the phaselocked loop 1002 includes phase discriminator, loop filter and voltage controlled oscillator VCO, the signal that user terminal 70 is received from local side as phase discriminator input signal, when the clock of user terminal 70 and local side is inconsistent, phaselocked loop passes through accurate phase demodulation, export the phase difference of user terminal 70 and local side, the signal consistent with local side is obtained by loop filtering and VCO again.

Principle explanation in claim to a method S503 understands that when the signal sent in local side meets the coefficient composition orthogonal matrix sent on any two lines road in the pilot tone subset of dmt signal, the signal that any user terminal 70 is received meets alr_lZ ^m- ¹ + a2r₂z^m-² + a3r₃z^m-³ + - - - + amr_m=0, so, the coefficient and predetermined coefficient equationof structure of the pilot tone subset for the m dmt signal that phaselocked loop 1002 can be received according to the user terminal 70 can by solving equation;Xiao carries out accurate phase demodulation except crosstalk.For example, the coefficient and predetermined coefficient equationof structure of the pilot tone subset for the m dmt signal that phaselocked loop 1002 can be received according to the user terminal 70： alr_lZ ^m-¹ + a2r₂z^m-² + a3r₃z^m + · · · + amr_m=0, so as to obtain the phase difference of the user terminal 70 and local side.

For example, user terminal 70 can handle the information from local side reception following the next rules to obtain accurately phase difference： 1st, since user terminal 70 receive dmt signal arbitrarily including the dmt signal of above-mentioned pilot tone；

2nd, user terminal 70 records continuous m dmt signal successively, is designated as rl, r2, r3 ..., r；

3rd, the predetermined coefficient equationof structure that user terminal 70 is sent according to the m dmt signal and local side received, for example, the predetermined coefficient that local side is sent is al, a2, a3, during am, the equation of user terminal construction is： a\rz^m' + a2r₂z^m-² + a3r₃z^m-³ +■■■ + amr_m= 0；

4th, user terminal 70 obtains phase difference z=z of the user terminal and local side from above-mentioned equationof structure.= ^ ;

5th, user terminal 70 using S as phase discriminator output.

6th, the clock of user terminal 70 is calibrated according to ^ by phaselocked loop 1002；Obtain the m dmt signal consistent with local side clock；Exemplary, user terminal 70 can periodically repeat above-mentioned regular 2 to 6, it is hereby achieved that the continuous signal consistent with local side clock.

It should be noted that, when the user terminal 70 that local side is connected is very more, local side can be grouped to user terminal 70, local side sends dmt signal to each group using the above method, the user terminal 70 in each group can be caused to carry out accurate clock recovery respectively, and then obtain the signal consistent with local side.

A kind of user terminal 70 provided in an embodiment of the present invention, each user terminal 70 receives the m dmt signal that local side is sent, and m dmt signal is sent from local side by the n bar line synchronizations that are connected with n user terminal 70 to each user terminal 70；Every circuit sends m dmt signal using one or more pilot tones；The corresponding one or more pilot tones of n groups at least one identical pilot tone subset on n bar circuits；And the coefficient sent on any two lines road in the pilot tone subset of dmt signal constitutes orthogonal matrix, user terminal 70 can carry out accurate clock alignment according to the m dmt signal received and obtain the signal consistent with local side clock.Overcome prior art and there is strong far-end interference due to spread spectrum, make the SNR for the clock synchronizing pilot signal that user terminal 70 receives very low, and then cause user terminal 70 from carrying out the defect of accurate calibration to clock.

On the other hand, the embodiments of the invention provide a kind of system of clock recovery, including the user terminal 70 described in local side 60 and any of the above-described embodiment described in any of the above-described embodiment.A kind of system of clock recovery provided in an embodiment of the present invention, local side 60 sends m dmt signal by the n bar line synchronizations that are connected with n user terminal 70 to each user terminal 70；Every circuit sends m dmt signal using one or more pilot tones；Correspondence on n bar circuits The one or more pilot tones of n groups at least one identical pilot tone subsets；And the coefficient sent on any two lines road in the pilot tone subset of DMT signals constitutes orthogonal matrix so that user terminal 70 can obtain the signal consistent with the clock of local side 60 according to m dmt signal.Overcome prior art and there is strong far-end interference due to spread spectrum, make the SNR for the clock synchronizing pilot signal that user terminal 70 receives very low, and then cause user terminal 70 from carrying out the defect of accurate calibration to clock.

It is apparent to those skilled in the art that, for convenience and simplicity of description, the specific work process of the system, apparatus, and unit of foregoing description may be referred to the corresponding process in preceding method embodiment, will not be repeated here.

In several embodiments provided herein, it should be understood that disclosed system, apparatus and method can be realized by another way.For example, device embodiment described above is only schematical, for example, the division of the unit, it is only a kind of division of logic function, there can be other dividing mode when actually realizing, such as multiple units or component can combine or be desirably integrated into another system, or some features can be ignored, or do not perform.Another, it, by some interfaces, the INDIRECT COUPLING or communication connection of device or unit, can be electrical, machinery or other forms that shown or discussed coupling or direct-coupling or communication connection each other, which can be,.

The unit illustrated as separating component can be or may not be physically separate, the part shown as unit can be or may not be physical location, a place can be located at, or can also be distributed on multiple NEs.Some or all of unit therein can be selected to realize the purpose of this embodiment scheme according to the actual needs.

In addition, each functional unit in each of the invention embodiment can be integrated in a processing unit or the independent physics of unit includes, can also two or more units it is integrated in a unit.Above-mentioned integrated unit can both be realized in the form of hardware, it would however also be possible to employ hardware adds the form of SFU software functional unit to realize.

The above-mentioned integrated unit realized in the form of SFU software functional unit, can be stored in a computer read/write memory medium.Above-mentioned SFU software functional unit is stored in a storage medium, including some instructions are to cause a computer equipment（Can be personal computer, server, or network equipment etc.）Perform the part steps of each embodiment methods described of the invention.And foregoing storage medium includes：USB flash disk, mobile hard disk, read-only storage（Read-Only Memory, abbreviation ROM), random access memory（Random Access Memory, abbreviation RAM), magnetic disc or CD etc. are various can be with the medium of store program codes. Finally it should be noted that：The above embodiments are merely illustrative of the technical solutions of the present invention, rather than its limitations；Although the present invention is described in detail with reference to the foregoing embodiments, it will be understood by those within the art that：It can still modify to the technical scheme described in foregoing embodiments, or carry out equivalent substitution to which part technical characteristic；And these modifications or replacement, the essence of appropriate technical solution is departed from the spirit and scope of various embodiments of the present invention technical scheme.

It is described above; only embodiment of the invention, but protection scope of the present invention is not limited thereto, any one skilled in the art the invention discloses technical scope in; change or replacement can be readily occurred in, should be all included within the scope of the present invention.Therefore, protection scope of the present invention should be based on the protection scope of the described claims.

Claims (18)

1. Claims

   1st, a kind of method of clock recovery, it is characterised in that methods described includes：

   The local side being connected with n user terminal is respectively that each user terminal generates m dmt signal；The local side sends m dmt signal by the n bar line synchronizations that are connected with the n user terminal to each user terminal；Wherein, every circuit sends the m dmt signal using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the dmt signal is sent on wherein any two lines road and constitutes orthogonal matrix, the user terminal number n is more than or equal to 2, and the m is more than the n;

   M dmt signal of the user terminal is used for the user terminal for receiving the m dmt signal according to the m dmt signal, obtains the signal consistent with the local side clock.

   2nd, the method for the clock recovery according to claim 1, it is characterised in that before the local side sends m dmt signal by the n bar line synchronizations that are connected with the n user terminal to each user terminal, methods described also includes：

   The local side sends configured information to each user terminal, the configured information includes the identification information and predetermined coefficient for the pilot tone subset for sending the DMT signals, and the predetermined coefficient constitutes orthogonal matrix with the coefficient sent on each circuit in the pilot tone subset of the dmt signal.

   3rd, the method for clock recovery according to claim 1 or 2, it is characterised in that the m is the smallest natural number more than the n.

   4th, the method for the clock recovery according to claim any one of 1-3, it is characterised in that the local side sends m dmt signal by the n bar line synchronizations that are connected with the n user terminal to each user terminal, including：

   Any n row of the local side respectively using orthogonal matrix W on the n bar circuits being connected with the n user terminal synchronously sends m dmt signal to each user terminal, wherein, the line number of the orthogonal matrix W is more than n, and the columns of the orthogonal matrix W is equal to m;

   Or,

   Any n row of the local side respectively using orthogonal matrix W on the n bar circuits being connected with the n user terminal synchronously send m dmt signal to each user terminal, wherein, the columns of the orthogonal matrix W is more than n, and the line number of the orthogonal matrix W is equal to m.

   5th, the method for clock recovery according to claim 4, it is characterised in that described=² , The orthogonal matrix W is the square formation W of m ranks_m, it is described $₁Recursive form be

   ^―' w_2l.

   W

   -w

   1 1

   1-1 wherein, and k is the natural number more than or equal to 1.

   6th, a kind of method of clock recovery, it is characterised in that methods described includes：

   Each user terminal receives the m dmt signal that local side is sent, the m dmt signal from the local side by the n bar line synchronizations that are connected with n user terminal to the transmission of each user terminal；Wherein, every circuit sends the m dmt signal using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the dmt signal is sent on wherein any two lines road and constitutes orthogonal matrix, the user terminal number n is more than or equal to 2, and the m is more than the n;Each user terminal according to the m dmt signal received, obtains the signal consistent with the local side clock respectively.

   7th, the method for the clock recovery according to claim 6, it is characterised in that before each user terminal receives the m dmt signal that local side is sent, methods described also includes：

   Each user terminal receives the configured information that the local side is sent, the configured information includes the identification information and predetermined coefficient for the pilot tone subset for sending the dmt signal, and the predetermined coefficient constitutes orthogonal matrix with the coefficient sent on each circuit in the pilot tone subset of the dmt signal.

   8th, the method for the clock recovery according to claim 6 or 7, it is characterised in that the m is the smallest natural number more than the n.

   9th, the method for the clock recovery according to claim any one of 6-8, it is characterized in that, the m dmt signal is synchronously sent from any n rows of the local side respectively using orthogonal matrix W on the n bar circuits being connected with the n user terminal to each user terminal, wherein, the line number of the orthogonal matrix W is more than n, and the columns of the orthogonal matrix W is equal to m;

   Or, synchronously m dmt signal is sent from any n row of the local side respectively using orthogonal matrix W on the n bar circuits being connected with the n user terminal to each user terminal, wherein, the columns of the orthogonal matrix W is more than n, and the line number of the orthogonal matrix W is equal to m.

   10th, the method for clock recovery according to claim 9, it is characterised in that described=² , The orthogonal matrix W is the square formation W of m ranks_m, it is described $₁Recursive form be

   ^―' w_2l.

   W

   -w

   1 1

   1-1 wherein, and k is the natural number more than or equal to 1.

   11st, the method for the clock recovery according to claim any one of 7-10, it is characterised in that each described user terminal obtains the signal consistent with the local side clock respectively according to the m dmt signal received, including：

   Each user terminal obtains the phase difference of each user terminal and the local side according to the m dmt signal received and the predetermined coefficient；

   Each user terminal carries out clock alignment according to the phase difference, obtains the signal consistent with the local side clock.

   12nd, a kind of local side, it is characterised in that including：

   Processor, for being respectively the n user terminal m dmt signal of generation being connected with the local side；

   Transmitter, m dmt signal is sent for the n bar line synchronizations by being connected with the n user terminal to each user terminal；Wherein, every circuit sends the m dmt signal using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the dmt signal is sent on wherein any two lines road and constitutes orthogonal matrix, the user terminal number n is more than or equal to 2, and the m is more than the n;

   M dmt signal of the user terminal is used for the user terminal for receiving the m dmt signal according to the m dmt signal, obtains the signal consistent with the local side clock.

   13rd, local side according to claim 12, it is characterised in that

   The transmitter is additionally operable to：Before m dmt signal being sent in the n bar line synchronizations by being connected with the n user terminal to each user terminal, configured information is sent to each user terminal, the configured information includes the identification information and predetermined coefficient for the pilot tone subset for sending the dmt signal, and the predetermined coefficient constitutes orthogonal matrix with the coefficient sent on each circuit in the pilot tone subset of the dmt signal.

   14th, the local side according to claim 12 or 13, it is characterised in that The m is the smallest natural number more than the n.

   15th, the local side according to claim any one of 12-14, it is characterised in that the transmitter is additionally operable to：Any n rows on the n bar circuits being connected with the n user terminal respectively using orthogonal matrix W synchronously send m dmt signal to each user terminal, wherein, the line number of the orthogonal matrix W is more than n, and the columns of the orthogonal matrix W is equal to m;

   Or be used for, any n row respectively using orthogonal matrix W on the n bar circuits being connected with the n user terminal synchronously send m dmt signal to each user terminal, wherein, the columns of the orthogonal matrix W is more than n, and the line number of the orthogonal matrix W is equal to m.

   16th, local side according to claim 15, it is characterised in that

   Described=², the orthogonal matrix W is the square formation W of m ranks_m, the W ^ 々 recursive forms are：

   1 1

   1-1 wherein, and k is the natural number more than or equal to 1.

   17th, a kind of user terminal, it is characterised in that including：

   Receiver, the m dmt signal for receiving local side transmission, the m dmt signal from the local side by the n bar line synchronizations that are connected with n user terminal to the transmission of each user terminal；Wherein, every circuit sends the m dmt signal using one or more pilot tones；The corresponding one or more of pilot tones of n groups at least one identical pilot tone subset on the n bars circuit；The coefficient in the pilot tone subset of the dmt signal is sent on wherein any two lines road and constitutes orthogonal matrix, the user terminal number n is more than or equal to 2, and the m is more than the n;Phaselocked loop, for the m dmt signal received according to the receiver, obtains the signal consistent with the local side clock.

   18th, user terminal according to claim 17, it is characterised in that

   The receiver is additionally operable to：Before the m dmt signal that local side is sent is received, receive the configured information that the local side is sent, the configured information includes the identification information and predetermined coefficient for the pilot tone subset for sending the dmt signal, and the predetermined coefficient constitutes orthogonal matrix with the coefficient sent on each circuit in the pilot tone subset of the dmt signal.

   19th, the user terminal according to claim 17 or 18, it is characterised in that The m is the smallest natural number more than the n.

   20th, the user terminal according to claim any one of 17-19, it is characterized in that, the m dmt signal is synchronously sent from any n rows of the local side respectively using orthogonal matrix W on the n bar circuits being connected with the n user terminal to each user terminal, wherein, the line number of the orthogonal matrix W is more than n, and the columns of the orthogonal matrix W is equal to m;

   Or, synchronously m dmt signal is sent from any n row of the local side respectively using orthogonal matrix W on the n bar circuits being connected with the n user terminal to each user terminal, wherein, the columns of the orthogonal matrix W is more than n, and the line number of the orthogonal matrix W is equal to m.

   21st, user terminal according to claim 20, it is characterised in that

   Described=², the orthogonal matrix W is the square formation W of m ranks_m, the W ^ 々 recursive forms are：

   2" 2"

   W

   2" 2"

   1 1

   1-1 wherein, and k is the natural number more than or equal to 1.

   22nd, the user terminal according to claim any one of 17-21, it is characterised in that the phaselocked loop is additionally operable to：

   The m dmt signal and the predetermined coefficient that are received according to each user terminal obtain the phase difference of each user terminal and the local side；

   Clock alignment is carried out according to the phase difference, the signal consistent with the local side clock is obtained.

   23rd, a kind of system of clock recovery, it is characterised in that including the user terminal described in the local side described in claim any one of 12-16 and claim any one of 17-22.