CN101459447A - Dynamic spectrum management method for reducing cross talk interference of digital subscriber line - Google Patents

Abstract

The invention discloses a dynamic frequency spectrum management method for reducing the crosstalk interference of digital subscriber lines, which has the advantages that twisted-pair lines with the same length in a cable bundle are divided into one group, and a reference line is reasonably led in to replace all twisted-pair lines in each group, the method is used without conducting the frequency spectrum optimization for all twisted-pair lines in the cable bundle, only needing to conduct the frequency spectrum distribution and bit load for the reference line, therefore, the dimensionality reduction is realized through the group division, and the computing complexity of the method is greatly improved compared with an ideal frequency spectrum management method, and the operand of the method of the invention approaches an iterate water injection method especially when the total number of the twisted-pair line in the cable bundle has a greater difference with the total number of the divided groups. When the dynamic frequency spectrum management method for reducing the crosstalk interference of digital user lines distributes the frequency spectrum and bit load among the distributed reference lines, the most reasonable sending power can be obtained through adopting a contrast search method, therefore, the performances of the method approach the ideal frequency spectrum management method, and the method can be effectively applied in the technical field of VDSL2 in view of the advantages.

Description

A kind of dynamic spectrum management method that reduces the Digital Subscriber Line cross-talk

Technical field

The present invention relates to a kind of Digital Subscriber Line cross-talk inhibition method of passing through, especially relate to a kind of dynamic spectrum management method that reduces the Digital Subscriber Line cross-talk.

Background technology

Fiber to the home is the final developing direction of broadband cabled Access Network.Yet, when extensively promoting optical fiber, be faced with many difficulties, in this case, market adopts progressively that Fiber To The Building, to the sub-district, arrive roadside etc., then by copper twisted pair cable access user.Along with the shortening of copper twisted pair cable transmission range and the increase of transmission bandwidth, from the also increase thereupon of cross-talk of adjacent lines, this cross-talk than about the strong 10～15dB of noise, has greatly influenced speed, distance and the quality of transfer of data usually.Therefore, suppress focus and the advanced subject that cross-talk just becomes present research.

The direction difference that cross-talk is transmitted data according to the user can be divided into far-end crosstalk (FEXT, Far End Crosstalk) and near-end crosstalk (NEXT, Near-End Crosstalk).In Digital Subscriber Line (DSL, Digital Subscriber Line) system, the transmission of up-downlink direction is usually by adopting different frequency ranges to avoid the influence of NEXT.But, make the influence of FEXT become very serious because the transmission range of VDSL2 (Very-high-bit-rate Digital Subscriber Loop, very-high-bit-rate digital subscriber loop) is shorter.

At present, the technology that reduces far-end crosstalk roughly has two classes: cross-talk inhibition technology and Dynamic Spectrum Management.It is a kind of coordination technique of signal level that cross-talk suppresses (crosstalk cancellation), and its main method has zero setting method (Zeroforcing), single order approach method, three diagonal angle approach methods.Several method during cross-talk suppresses all has only when receiving terminal and transmitting terminal have at least an end to satisfy cooperation relation, just can be employed.But the phone local side (abbreviation local side) (CO, Centre office) or the user side of existing DSL system are unlikely cooperated, and at this moment, must use dynamic spectrum management method to reduce the influence of cross-talk.

Dynamic Spectrum Management (DSM, Dynamic spectrum management) is the spectral balance scheme in a kind of multi-user of the being applied to DSL system.The DSM scheme is intended to adopt the method for dynamic spectrum balance to promote line speed, distance and stability, or under the situation that satisfies performance and stability requirement (as speed, noise margin and the error rate etc.), send signal with minimal power, concentrate various parameter configuration of optimum management and signal transmitting power spectrum density by a series of method, even coordinate the transmission and the reception of signal in the whole bunch of cables, make circuit transmission performance optimization in the whole bunch of cables.

The DSL transceiver has three kinds of mode of operations: rate adaptation pattern, power adaptive pattern, tolerance limit adaptive model wherein, are most widely used with the rate adaptation pattern.The spectrum management of rate adaptation pattern is defined as:

$\underset{s^{}}{\mathrm{<figure-callout\; id="1"\; label="max\; s"\; filenames="A200810164223E00221.png"\; state="\{\{state\}\}">max</figure-callout>}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{R}_n^{\&prime;}$

$s.t.\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{s}_k^n\&le;P_n,n=1,...,N,$

$R_n^{\&prime;}\&GreaterEqual;R_n^{t\arg \mathrm{et}},n=1,...,N$

Wherein, N is a number of users, because a twisted-pair feeder connects a user, so N also is the sum of twisted-pair feeder simultaneously, R ' is the transmission rate that the user of n bar twisted-pair feeder connection can reach, and its calculation expression is:

$R_n^{\&prime;}=f_s\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\log }_2(1+\frac{{\left|h_k^{n,n}\right|}^2{s}_k^n}{\mathrm{\&Gamma;}(\underset{m=1,m\&NotEqual;n}{\overset{N}{\mathrm{\&Sigma;}}}{\left|h_k^{n,m}\right|}^2{s}_k^m+{\mathrm{\&sigma;}}_k^n)}),$

In addition

Be nth user's targeted rate, P _nBe nth user's gross power restriction, K is a total number of sub-carriers, f _sBe character rate, Be the transmitted power of n bar twisted-pair feeder on k subcarrier,

Be the transmitted power of m bar twisted-pair feeder on k subcarrier, Γ is a signal to noise ratio difference,

Be the impulse response of the fading channel of n bar twisted-pair feeder on k subcarrier,

Be illustrated in the cross-talk that m bar twisted-pair feeder forms n bar twisted-pair feeder on k the subcarrier, Be the noise power of n bar twisted-pair feeder on k subcarrier.Operand that above-mentioned optimal problem is found the solution and total number of sub-carriers K exponent function relation, so computation complexity is quite big.For addressing this problem, a lot of dynamic spectrum management methods are suggested in succession, and are wherein typical with iteration water-filling method and desirable frequency spectrum distributing method.

Iteration water-filling method (IW, Iterative Waterfilling) is a kind of dynamic spectrum management method the earliest.IW studies noncooperative spectrum management problem from the game angle, promptly the user in order to realize maximum bit rate separately and to vie each other frequency spectrum and do not take into account thus the user that brings between crosstalk.The Lagrange's equation of this method on k subcarrier is:

$\underset{s_k^n}{\max }{\log }_2(1+\frac{1}{\mathrm{\&Gamma;}}\frac{{\left|h_k^{n,n}\right|}^2{s}_k^n}{\underset{m=1,m\&NotEqual;n}{\overset{N}{\mathrm{\&Sigma;}}}{\left|h_k^{n,m}\right|}^2{s}_k^m+{\mathrm{\&sigma;}}_k^n})-{\mathrm{\&lambda;}}_n{s}_k^n,$

Utilize the thought of water filling to separate Lagrange's equation on above-mentioned k the subcarrier, obtain

$s_k^n={(\frac{1}{{\mathrm{\&lambda;}}_n}-\mathrm{\&Gamma;}\frac{\underset{m=1,m\&NotEqual;n}{\overset{N}{\mathrm{\&Sigma;}}}{\left|h_k^{n,m}\right|}^2{s}_k^m+{\mathrm{\&sigma;}}_k^n}{{\left|h_k^{n,n}\right|}^2})}^{+}\&ForAll;n.$ Wherein, λ _nBe the Lagrange multiplier of power controlling,

(a) ⁺=max (a, 0),

Be the transmitted power of n bar twisted-pair feeder on k subcarrier,

Be the transmitted power of m bar twisted-pair feeder on k subcarrier, Γ is a signal to noise ratio difference,

Be the impulse response of the fading channel of n bar twisted-pair feeder on k subcarrier,

Be illustrated in the cross-talk that m bar twisted-pair feeder forms n bar twisted-pair feeder on k the subcarrier,

Be the noise power of n bar twisted-pair feeder on k subcarrier, the IW biggest advantage is to realize that simply computation complexity and number of users N are linear, but the performance of IW is imperfect, particularly when having near-far interference.

Desirable frequency spectrum distributing method (OSB, Optimal spectrum balancing) is a kind of dynamic spectrum management method of best performance, and its operand and total number of sub-carriers K are linear.The Lagrange's equation of OSB on k subcarrier is: $\begin{array}{c}\underset{\mathrm{\&omega;},\mathrm{\&lambda;}}{\min }\underset{k=1}{\overset{\mathrm{<figure-callout\; id="1"\; label="K\; max\; s"\; filenames="A200810164223E00221.png"\; state="\{\{state\}\}">K</figure-callout>}}{\mathrm{\&Sigma;}}}\underset{s^{}}{\max }\underset{}{{}^1,...,s^N,R}{J}_k({\mathrm{<figure-callout\; id="1"\; label="s\; k"\; filenames="A200810164223E00221.png"\; state="\{\{state\}\}">s</figure-callout>}}_k^{},...,s_k^N,\mathrm{\&omega;},\mathrm{\&lambda;})\\ \begin{array}{cc}s.t.& {\mathrm{\&lambda;}}_n\&GreaterEqual;0,n=1...N\\ & {\mathrm{\&omega;}}_n\&GreaterEqual;0,n=1...N\end{array}\end{array},$ Wherein, Lagrangian J _kBe defined as: $\begin{array}{cc}{J}_k=\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{\mathrm{\&omega;}}_n{f}_s{b}_k^n-\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{\mathrm{\&lambda;}}_n{s}_k^n& k=1,\&CenterDot;\&CenterDot;\&CenterDot;,K\end{array},$ ω _nBe the Lagrange multiplier of control speed, ω=[ω ₁..., ω _N], λ _nBe the Lagrange multiplier of power controlling, λ=[λ ₁..., λ _N].Because Lagrangian J _kBe a non-convex function, must search for all users' power spectral density simultaneously that its hunting zone and number of users N exponent function relation, huge amount of calculation make very difficulty of its practice so will obtain the optimal value of this function.

Summary of the invention

Technical problem to be solved by this invention provides the dynamic spectrum management method that reduces the Digital Subscriber Line cross-talk that a kind of performance is excellent, computation complexity is low.

The present invention solves the problems of the technologies described above the technical scheme that is adopted: a kind of dynamic spectrum management method that reduces the Digital Subscriber Line cross-talk may further comprise the steps:

1. according to the channel transfer characteristic of twisted-pair feeder, many twisted-pair feeders in the bunch of cables in the multi-user DSL system are divided into the M group, r are arranged in every group _nBar has the twisted-pair feeder of same channel transmission characteristic, and the set of every group of all interior twisted-pair feeders is expressed as L _n={ l _n(1) ..., l _n(r _n), wherein, n=1 ..., M, l _n(1) the 1st twisted-pair feeder in the expression n group, l _n(r _n) the interior r of expression n group _nBar twisted-pair feeder, each the bar twisted-pair feeder in every group have from crosstalking except that the group of other twisted-pair feeders self in same group, and each interior bar twisted-pair feeder of each group has from other does not crosstalk between the group of interior twisted-pair feeder on the same group;

2. to each the bar twisted-pair feeder allocation of transmit power on K subcarrier in each group, wherein to the r in the n group _nThe bar twisted-pair feeder distributes identical transmitted power on k subcarrier Obtain the bit number of p bar twisted-pair feeder on k subcarrier in the n group

Wherein, Γ is a signal to noise ratio difference, l _n(p) the p bar twisted-pair feeder in the expression n group, p=1 ..., r _n, k=1 ..., K, K represent the sum of subcarrier, N represents number of users,

The impulse response of representing the fading channel of p bar twisted-pair feeder on k subcarrier in the n group,

Represent to crosstalk in the group that the q bar twisted-pair feeder in the n group forms on k subcarrier the p bar twisted-pair feeder in the n group,

Represent that m organizes interior q bar twisted-pair feeder the p bar twisted-pair feeder in the n group is crosstalked between the group that forms on k the subcarrier,

Represent the noise power of p bar twisted-pair feeder on k subcarrier in the n group;

3. calculate the average channel transmission characteristic of all twisted-pair feeders on each subcarrier in each group respectively, introduce the corresponding virtual reference line according to the average channel transmission characteristic, calculate the fading channel and the crosstalk channels of virtual reference line, calculate the virtual transmission model of virtual reference line again according to fading channel and crosstalk channels, wherein on k subcarrier, calculate the average channel transmission characteristic of all twisted-pair feeders on k subcarrier in each group, introduce corresponding M bar virtual reference line according to the average channel transmission characteristic, for n bar virtual reference line, its fading channel on k subcarrier is

${\stackrel{\&OverBar;}{h}}_{k,\mathrm{direct}}^{n,n}=\frac{1}{r_n}\underset{p=1}{\overset{r_n}{\mathrm{\&Sigma;}}}\left|h_k^{l_n\left(p\right),l_n\left(p\right)}\right|,$ Wherein, n=1 ... M, k=1 ..., K, K represent the sum of subcarrier, l _n(p) the p bar twisted-pair feeder in the expression n group,

Represent the impulse response of the fading channel of p bar twisted-pair feeder on k subcarrier in the n group, its crosstalk channels on k subcarrier is

${\stackrel{\&OverBar;}{h}}_{k,\mathrm{crosstalk}}^{n,m}=\left\{\begin{array}{c}\frac{1}{r_n}\underset{p=1}{\overset{r_n}{\mathrm{\&Sigma;}}}\underset{q=1,q\&NotEqual;p}{\overset{r_m}{\mathrm{\&Sigma;}}}\left|h_k^{l_n\left(p\right),l_m\left(q\right)}\right|,n=m\\ \frac{1}{r_n}\underset{p=1}{\overset{r_n}{\mathrm{\&Sigma;}}}\underset{q=1}{\overset{r_m}{\mathrm{\&Sigma;}}}\left|h_k^{l_n\left(p\right),l_m\left(q\right)}\right|,n\&NotEqual;m\end{array}\right.,$ Wherein, n=1 ... M, m=1 ... M,

Represent that m organizes interior q bar twisted-pair feeder the p bar twisted-pair feeder in the n group is crosstalked between the group that forms on k the subcarrier; Fading channel according to n bar virtual reference line

And crosstalk channels Calculate the virtual transmission model of n bar virtual reference line on k subcarrier

${\stackrel{\&OverBar;}{y}}_k^n={\stackrel{\&OverBar;}{h}}_{k,\mathrm{drect}}^{n,n}{x}_k^n+\underset{m=1}{\overset{M}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{h}}_{k,\mathrm{crosstalk}}^{n,m}{x}_k^m+z_k^n,$ Wherein,

Represent the transmission signal of n bar virtual reference line on k subcarrier,

Represent the transmission signal of m bar virtual reference line on k subcarrier,

Represent the white Gaussian noise of n bar virtual reference line on k subcarrier; Every virtual reference line has from the alien cross-talk except that other virtual reference line self, each bar virtual reference line has simultaneously from crosstalking, the mean value of crosstalking in the group that this value of crosstalking certainly has for all twisted-pair feeders in the group that is substituted by this virtual reference line;

4. according to the virtual transmission model of each bar virtual reference line on each subcarrier, calculate the maximum number bits that each bar virtual reference line can load on each subcarrier, wherein to n bar virtual reference line, according to the virtual transmission model of n bar virtual reference line on k subcarrier

Obtaining the maximum number bits that can load of n bar virtual reference line on k subcarrier is ${\stackrel{\&OverBar;}{b}}_k^n{=\log }_2(1+\frac{1}{\mathrm{\&Gamma;}}\frac{{\left|{\stackrel{\&OverBar;}{h}}_{k,\mathrm{drect}}^{n,n}\right|}^2{s}_k^n}{\underset{m=1}{\overset{M}{\mathrm{\&Sigma;}}}{\left|{\stackrel{\&OverBar;}{h}}_{k,\mathrm{crosstalk}}^{n,m}\right|}^2{s}_k^m+{\mathrm{\&sigma;}}_k^n}),$ Wherein, Γ is a signal to noise ratio difference,

Represent the transmitted power of n bar virtual reference line on k subcarrier,

Represent the transmitted power of m bar virtual reference line on k subcarrier,

Be the noise power of n bar virtual reference line on k subcarrier;

5. be each bar virtual reference line allocation of transmit power, detailed process is: 5.-1, for all virtual reference line, and initialization first Lagrange multiplier With second Lagrange multiplier 5.-2, calculate the transmitted power of all virtual reference line on all subcarriers, on k subcarrier, carry out M dimension contrast search, obtain the transmitted power of all virtual reference line on k subcarrier, ${\mathrm{<figure-callout\; id="1"\; label="s\; k"\; filenames="A200810164223E00221.png"\; state="\{\{state\}\}">s</figure-callout>}}_k^{},...,s_k^M=\arg \underset{s_k^{}}{\mathrm{<figure-callout\; id="1"\; label="max\; s\; k"\; filenames="A200810164223E00221.png"\; state="\{\{state\}\}">max</figure-callout>}}{\stackrel{\&OverBar;}{J}}_k,$ Wherein,

Be the Lagrangian of all virtual reference line on k subcarrier, ${\stackrel{\&OverBar;}{J}}_k=\underset{n=1}{\overset{M}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n{f}_s{\stackrel{\&OverBar;}{b}}_k^n-\underset{n=1}{\overset{M}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n{s}_k^n,$ K=1 ..., K, K represent the sum of subcarrier, f _sBe character rate,

Be the maximum number bits that can load of n bar virtual reference line on k subcarrier,

Be the transmitted power of n bar virtual reference line on k subcarrier; 5.-3, judge whether all virtual reference line satisfy the restrictive condition of speed and power, for n bar virtual reference line, judge whether n bar virtual reference line satisfies condition: $R_n^{t\arg \mathrm{et}}=f_s\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{b}}_n^k$ And $P_n=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{s}_k^n,$ Wherein, n=1 ... M,

Be the targeted rate of n bar virtual reference line, P _nBe the maximum transmit power of n bar virtual reference line,, then adjust first Lagrange multiplier of n bar virtual reference line if n bar virtual reference line does not satisfy condition

With second Lagrange multiplier

, and return execution in step 5.-2; If n bar virtual reference line satisfies condition, then re-execute step and continue 5.-3 to judge whether next bar virtual reference line satisfies condition, when all satisfying condition, all virtual reference line finish execution in step 5.;

6. the transmitted power that each bar virtual reference line distribution is obtained for n bar virtual reference line, on each subcarrier is distributed the transmitted power that obtain with n bar virtual reference line as the transmitted power of each bar twisted-pair feeder in the group that substitutes separately $s^n=[s_1^n,\&CenterDot;\&CenterDot;\&CenterDot;s_k^n,\&CenterDot;\&CenterDot;\&CenterDot;,s_K^n]$ The n that substitutes as this virtual reference line organizes the interior transmitted power of each bar twisted-pair feeder on each subcarrier $s^{l_n}=[s_1^{l_n},\&CenterDot;\&CenterDot;\&CenterDot;s_k^{l_n},\&CenterDot;\&CenterDot;\&CenterDot;,s_K^{l_n}],$ Wherein, k=1 ..., K, K represent the sum of subcarrier,

Be the transmitted power of n bar virtual reference line on the k subcarrier,

Be the interior transmitted power of each bar twisted-pair feeder on the k subcarrier of n group that n bar virtual reference line substitutes.

Described step is adjusted first Lagrange multiplier of n bar virtual reference line in 5.-3

With second Lagrange multiplier

Computational process be: defining adjusted first Lagrange multiplier is

, define adjusted first Lagrange multiplier and be

, ${\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n\&prime;={[{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n+\mathrm{\&epsiv;}(R_n^{t\arg \mathrm{et}}-R_n)]}^{+},$ ${\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n\&prime;={[{\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n+\mathrm{\&epsiv;}(\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{s}_k^n-P_n)]}^{+},$ Wherein, ε is a step factor,

Be the targeted rate of n bar virtual reference line, R _nBe the transmission rate of n bar virtual reference line, $R_n=f_s\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{b}}_n^k,$ P _nBe the maximum transmit power of n bar virtual reference line,

Be the transmitted power of n bar virtual reference line on k subcarrier,

Be the maximum number bits that can load of n bar virtual reference line on k subcarrier, f _sBe character rate; With adjusted first Lagrange multiplier

Assignment is given

,

=

, with adjusted second Lagrange multiplier

Assignment is given

,

=

Described step is adjusted first Lagrange multiplier of n bar virtual reference line in 5.-3

With second Lagrange multiplier

Computational process be: defining adjusted first Lagrange multiplier is

, define adjusted first Lagrange multiplier and be

, $\left[\begin{array}{c}{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n\&prime;\\ {\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n\&prime;\end{array}\right]={(\left[\begin{array}{c}{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n\\ {\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n\end{array}\right]-\mathrm{\&epsiv;}\left[\begin{array}{c}{R}_n-R_n^{t\arg \mathrm{et}}\\ P_n-\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{s}_k^n\end{array}\right])}^{+},$ Wherein, ε is a step factor, R _nBe the transmission rate of n bar virtual reference line, $R_n=f_s\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{b}}_n^k,$

Be the targeted rate of n bar virtual reference line, P _nBe the maximum transmit power of n bar virtual reference line,

Be the transmitted power of n bar virtual reference line on k subcarrier,

Be the maximum number bits that can load of n bar virtual reference line on k subcarrier, f _sBe character rate; With adjusted first Lagrange multiplier

Assignment is given

,

=

, with adjusted second Lagrange multiplier

Assignment is given

,

=

Compared with prior art, the invention has the advantages that the twisted-pair feeder by having equal length in the same bunch of cables in the digital subscriber line system is divided into one group, and rationally introduce a virtual reference line and replace all interior twisted-pair feeders of each group, the channel transfer characteristic of this virtual reference line is represented the average channel transmission characteristic of all twisted-pair feeders in the corresponding group, and each bar virtual reference line is made spectrum allocation may and bit load, obtain the transmitted power of every virtual reference line, the transmitted power of each the bar twisted-pair feeder in again the transmitted power of these virtual reference line being divided into groups as correspondence, thereby realize the dimensionality reduction purpose, because the inventive method need not all twisted-pair feeders in the bunch of cables are carried out frequency spectrum optimization, and only need virtual reference line is made spectrum allocation may and bit loading, so more satisfactory spectrum management method of computation complexity of the inventive method, obtained very big improvement, when especially the sum of twisted-pair feeder and total number packets differ bigger in the bunch of cables, the operand of the inventive method will approach the iteration water-filling method; In the frequency spectrum and bit loading of the present invention between the assigned references line, adopt the method for constantly contrast search to try to achieve the most rational transmitted power, therefore the performance of the inventive method is approached desirable spectrum management method, and have greatly improved than the iteration water-filling method, The above results is verified by measured data; In view of above-mentioned advantage the inventive method can effectively be applied to the VDSL2 technical field.

Description of drawings

Fig. 1 is a multi-user DSL system schematic;

Fig. 2 is a virtual reference line model schematic diagram;

Fig. 3 is the simulated environment schematic diagram of topological structure Network Based;

The rate domain comparison diagram of the inventive method and iteration water-filling method when Fig. 4 is 600m and 75m;

The rate domain comparison diagram of the inventive method and iteration water-filling method when Fig. 5 is 600m and 150m;

The rate domain comparison diagram of the inventive method and iteration water-filling method when Fig. 6 is 600m and 300m.

Embodiment

Below in conjunction with accompanying drawing the invention process is described in further detail.

A kind of dynamic spectrum management method that reduces the Digital Subscriber Line cross-talk, this method be by the grouping dimensionality reduction mode realize, may further comprise the steps:

1. in multi-user DSL system, according to the DSL channel model as can be known, the fading characteristic of channel and crosstalk effect respectively with bunch of cables in the length of twisted-pair feeder (being Digital Subscriber Line) relevant with coupling distance.The twisted-pair feeder that is to say equal length has close channel transfer characteristic, promptly have close fading channel transmission characteristic and crosstalk channels transmission characteristic, since have close fading channel and crosstalk channels transmission characteristic, just there is no need one by one every twisted-pair feeder to be carried out Dynamic Spectrum Management.Usually can the twisted-pair feeder in the same bunch of cables be divided into several groups according to identical twisted-pair feeder length, these isometric twisted-pair feeders just can adopt identical spectrum allocation may and identical power allocation scheme.Twisted-pair feeder number in the general bunch of cables is 25,50 or 100 not to be waited.

For multi-user DSL system shown in Figure 1, theoretically can be according to the channel transfer characteristic of the fading channel and the crosstalk channels of twisted-pair feeder, many twisted-pair feeders in the bunch of cables are divided into the M group, can divide into groups according to the length of twisted-pair feeder in the actual mechanical process, the twisted-pair feeder that is about to have equal length is divided into one group, but the twisted-pair feeder of equal length and few in the strictness, it is considered herein that to differ between two twisted-pair feeders and all can think to have equal length about 4-5 rice, can divide in same group.Has r in every group _nThe twisted-pair feeder of bar same channel transmission characteristic, the set of every group of all interior twisted-pair feeders is expressed as L _n={ l _n(1) ..., l _n(r _n), wherein, n=1 ..., M, l _n(1) the 1st twisted-pair feeder in the expression n group, l _n(r _n) the interior r of expression n group _nThe bar twisted-pair feeder.After the twisted-pair feeder grouping in the bunch of cables, every twisted-pair feeder in every group is subjected to cross-talk (being the impulse response of the crosstalk channels of each bar twisted-pair feeder), cross-talk be divided into crosstalk in the group and organize between crosstalk, crosstalking in the group is meant electromagnetic coupled between the twisted-pair feeder in same group, crosstalks between group to be meant the cross-talk of other group to the twisted-pair feeder in a certain group.Channel transfer characteristic comprises crosstalk channels transmission characteristic and fading channel transmission characteristic.

2. to each the bar twisted-pair feeder allocation of transmit power on K subcarrier in each group, wherein to the r in the n group _nThe bar twisted-pair feeder distributes identical transmitted power on k subcarrier

Obtain the bit number of p bar twisted-pair feeder on k subcarrier in the n group

Wherein, Γ is a signal to noise ratio difference, and Γ is a function about coding gain, noise margin and target error rate, l _n(p) the p bar twisted-pair feeder in the expression n group, p=1 ..., r _n, k=1 ..., K, K represent the sum of subcarrier, N represents the sum of number of users or twisted-pair feeder, because a twisted-pair feeder connects a user, N also represents the sum of twisted-pair feeder, i.e. N=r simultaneously ₁+ r ₂+ ... + r _n+ ... + r _M, The impulse response of representing the fading channel of p bar twisted-pair feeder on k subcarrier in the n group,

Represent to crosstalk in the group that the q bar twisted-pair feeder in the n group forms on k subcarrier the p bar twisted-pair feeder in the n group, Represent that m organizes interior q bar twisted-pair feeder the p bar twisted-pair feeder in the n group is crosstalked between the group that forms on k the subcarrier,

Represent the noise power of p bar twisted-pair feeder on k subcarrier in the n group;

3. in order to reduce operand, the inventive method is calculated the average channel transmission characteristic of all twisted-pair feeders on each subcarrier in each group earlier respectively, the average channel transmission characteristic comprises average fading channel transmission characteristic and average crosstalk channels transmission characteristic, introduce the corresponding virtual reference line according to the average channel transmission characteristic, calculate the fading channel and the crosstalk channels of virtual reference line then, according to the virtual transmission model of fading channel and crosstalk channels calculating virtual reference line, Fig. 2 has described the corresponding reference line model schematic diagram of multi-user DSL system shown in Figure 1 again.Virtual reference line be a virtual line to rather than group in actual twisted-pair feeder, the channel transfer characteristic of virtual reference line can be represented the average channel transmission characteristic of twisted-pair feeder in the corresponding group.If the transfer function of the fading channel of twisted-pair feeder and crosstalk channels is roughly close in the group, the transmission performance of each bar twisted-pair feeder in this group can be represented in the achievable rate territory that then substitutes the virtual reference line of all twisted-pair feeders in this group.Crosstalk in every the twisted-pair feeder in grouping back is not only organized and crosstalk between also being organized, putting before this, substitute every group in each bar virtual reference line of all twisted-pair feeders also be subjected to two cross-talk simultaneously, at this two being crosstalked is called alien cross-talk and crosstalks certainly.Alien cross-talk is meant the cross-talk from other virtual reference line, the mean value of its value for crosstalking between the group that all twisted-pair feeders are subjected in the replaced group, be meant own cross-talk from crosstalking, the mean value of its value for crosstalking in the group that all twisted-pair feeders are received in the replaced group.

On k subcarrier, calculate the average channel transmission characteristic of all twisted-pair feeders on k subcarrier in each group, introduce corresponding M bar virtual reference line according to the average channel transmission characteristic, for n bar virtual reference line, its fading channel on k subcarrier is ${\stackrel{\&OverBar;}{h}}_{k,\mathrm{direct}}^{n,n}=\frac{1}{r_n}\underset{p=1}{\overset{r_n}{\mathrm{\&Sigma;}}}\left|h_k^{l_n\left(p\right),l_n\left(p\right)}\right|,$ Wherein, n=1 ... M, k=1 ..., K, K represent the sum of subcarrier, l _n(p) the p bar twisted-pair feeder in the expression n group, Represent the impulse response of the fading channel of p bar twisted-pair feeder on k subcarrier in the n group, its crosstalk channels on k subcarrier is

${\stackrel{\&OverBar;}{h}}_{k,\mathrm{crosstalk}}^{n,m}=\left\{\begin{array}{c}\frac{1}{r_n}\underset{p=1}{\overset{r_n}{\mathrm{\&Sigma;}}}\underset{q=1,q\&NotEqual;p}{\overset{r_m}{\mathrm{\&Sigma;}}}\left|h_k^{l_n\left(p\right),l_m\left(q\right)}\right|,n=m\\ \frac{1}{r_n}\underset{p=1}{\overset{r_n}{\mathrm{\&Sigma;}}}\underset{q=1}{\overset{r_m}{\mathrm{\&Sigma;}}}\left|h_k^{l_n\left(p\right),l_m\left(q\right)}\right|,n\&NotEqual;m\end{array}\right.,$ Wherein, n=1 ... M, m=1 ... M,

Represent that m organizes interior q bar twisted-pair feeder the p bar twisted-pair feeder in the n group is crosstalked between the group that forms on k the subcarrier; Fading channel according to n bar virtual reference line

And crosstalk channels

Calculate the virtual transmission model of n bar virtual reference line on k subcarrier

${\stackrel{\&OverBar;}{y}}_k^n={\stackrel{\&OverBar;}{h}}_{k,\mathrm{drect}}^{n,n}{x}_k^n+\underset{m=1}{\overset{M}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{h}}_{k,\mathrm{crosstalk}}^{n,m}{x}_k^m+z_k^n,$ Wherein,

Represent the transmission signal of n bar virtual reference line on k subcarrier,

Represent the transmission signal of m bar virtual reference line on k subcarrier,

Represent the white Gaussian noise of n bar virtual reference line on k subcarrier.

4. according to the virtual transmission model of each bar virtual reference line on each subcarrier, calculate the maximum number bits that each bar virtual reference line can load on each subcarrier, wherein to n bar virtual reference line, according to the virtual transmission model of n bar virtual reference line on k subcarrier

, obtain the maximum number bits that can load of n bar virtual reference line on k subcarrier and be ${\stackrel{\&OverBar;}{b}}_k^n={\log }_2(1+\frac{1}{\mathrm{\&Gamma;}}\frac{{\left|{\stackrel{\&OverBar;}{h}}_{k,\mathrm{drect}}^{n,n}\right|}^2{s}_k^n}{\underset{m=1}{\overset{M}{\mathrm{\&Sigma;}}}{\left|{\stackrel{\&OverBar;}{h}}_{k,\mathrm{crosstalk}}^{n,m}\right|}^2{s}_k^m+{\mathrm{\&sigma;}}_k^n}),$ Wherein, Γ is a signal to noise ratio difference,

Represent the transmitted power of n bar virtual reference line on k subcarrier,

Represent the transmitted power of m bar virtual reference line on k subcarrier,

Be the noise power of n bar virtual reference line on k subcarrier.

5. finish after twisted-pair feeder grouping and the virtual reference line Model Calculation, now by distributing frequency spectrum to handle cross-talk between the virtual reference line, like this by the realization dimension-reduction treatment of dividing into groups.Spectrum management optimization problem after the twisted-pair feeder grouping is: $\begin{array}{cc}\underset{s^{}}{\mathrm{<figure-callout\; id="1"\; label="max\; s"\; filenames="A200810164223E00221.png"\; state="\{\{state\}\}">max</figure-callout>}}& \underset{n=1}{\overset{M}{\mathrm{\&Sigma;}}}{R}_n\\ s.t.& \underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{s}_k^n\&le;P_n,n=1...M\\ & R_n\&GreaterEqual;R_n^{t\arg \mathrm{et}}n=1...M\end{array},$

Wherein, $R_n=f_s\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{b}}_n^k,$ The transmission rate of representing n bar virtual reference line, f _sBe character rate,

Be the targeted rate of n bar virtual reference line, P _nIt is the maximum transmit power of n bar virtual reference line.

Compare with desirable spectrum management method, the present invention does not carry out frequency spectrum optimization to all twisted-pair feeders in the bunch of cables, and only each group corresponding virtual reference line is made spectrum allocation may and bit loading, obtain the transmitted power of every virtual reference line, with the transmitted power of these virtual reference line transmitted power as each the bar twisted-pair feeder in the correspondence group, the demand pairs of spectrum allocation may are reduced greatly, so the more satisfactory spectrum management method of the computation complexity of this method have greatly improved.

The dual problem of the spectrum management optimization problem in the bunch of cables after all twisted-pair feeder groupings is expressed as follows:

$\begin{array}{cc}\underset{\mathrm{\&omega;},\mathrm{\&lambda;}}{\min }& \underset{s^{}}{\mathrm{<figure-callout\; id="1"\; label="max\; s"\; filenames="A200810164223E00221.png"\; state="\{\{state\}\}">max</figure-callout>}}\stackrel{\&OverBar;}{J}\\ s.t.& {\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n\&GreaterEqual;0,n=1...M\\ & {\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n\&GreaterEqual;0,n=1...M\end{array},$

Wherein,

$\stackrel{\&OverBar;}{J}=\underset{n=1}{\overset{M}{\mathrm{\&Sigma;}}}{R}_n+\underset{n=1}{\overset{M}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n(R_n-R_n^{t\arg \mathrm{et}})+\underset{n=1}{\overset{M}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n(P_n-\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{s}_k^n)$

$=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}(\underset{n=1}{\overset{M}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n{f}_s{\stackrel{\&OverBar;}{b}}_k^n-\underset{n=1}{\overset{M}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n{s}_k^n)+\underset{n=1}{\overset{M}{\mathrm{\&Sigma;}}}({\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n{P}_n-{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n{R}_n^{t\arg \mathrm{et}}),$

$=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{J}}_k+\underset{n=1}{\overset{M}{\mathrm{\&Sigma;}}}({\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n{P}_n-{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n{R}_n^{t\arg \mathrm{et}})$

For being used to adjust the Lagrange multiplier of speed, in the present embodiment, should

Be defined as first Lagrange multiplier,

For being used to adjust the Lagrange multiplier of power, in the present embodiment, should

Be defined as second Lagrange multiplier.Because

Be a constant, so can be write optimization problem as following expression usually:

$\begin{array}{cc}\underset{\mathrm{\&omega;},\mathrm{\&lambda;}}{\min }& \underset{k=1}{\overset{\mathrm{<figure-callout\; id="1"\; label="K\; max\; s"\; filenames="A200810164223E00221.png"\; state="\{\{state\}\}">K</figure-callout>}}{\mathrm{\&Sigma;}}}\underset{s^{}}{\max }\underset{}{{}^1,...,s^M}{\stackrel{\&OverBar;}{J}}_k\\ s.t.& {\mathrm{\&lambda;}}_n\&GreaterEqual;0,n=1...M\\ & {\mathrm{\&omega;}}_n\&GreaterEqual;0,n=1...M\end{array},$

For k subcarrier, desirable power distribution method is exactly the transmitted power vector $s_{}$ ${}_1=[s_{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="A200810164223E00221.png"\; state="\{\{state\}\}">k</figure-callout>}}^1,...,s_k^M]$ Make

Maximum, that is: $s_{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="A200810164223E00221.png"\; state="\{\{state\}\}">k</figure-callout>}}^1,...,s_k^M=\arg \underset{s_{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="A200810164223E00221.png"\; state="\{\{state\}\}">k</figure-callout>}}^1,...,s_k^M}{\max }{\stackrel{\&OverBar;}{J}}_k,$

The inventive method is each bar virtual reference line allocation of transmit power on each subcarrier, and detailed process is:

5.-1, for all virtual reference line, initialization first Lagrange multiplier With second Lagrange multiplier

5.-2, calculate the transmitted power of all virtual reference line on all subcarriers, k is from 1 to K circulation, on k subcarrier, n circulates from 1 to M, to n bar virtual reference line in the interval

In search out feasible

The value maximum

Value, wherein

The maximum of representing the transmitted power of n bar virtual reference line on k subcarrier obtains the transmitted power of all virtual reference line on k subcarrier, $s_{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="A200810164223E00221.png"\; state="\{\{state\}\}">k</figure-callout>}}^1,...,s_k^M=\arg \underset{s_{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="A200810164223E00221.png"\; state="\{\{state\}\}">k</figure-callout>}}^1,...,s_k^M}{\max }{\stackrel{\&OverBar;}{J}}_k,$ Wherein,

Be the Lagrangian of all virtual reference line on k subcarrier, ${\stackrel{\&OverBar;}{J}}_k=\underset{n=1}{\overset{M}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n{f}_s{\stackrel{\&OverBar;}{b}}_k^n-\underset{n=1}{\overset{M}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n{s}_k^n,$ K=1 ..., K, K represent the sum of subcarrier, f _sBe character rate,

Be the maximum number bits that can load of n bar virtual reference line on k subcarrier,

Be the transmitted power of n bar virtual reference line on k subcarrier; Owing to all need in the interval for each bar virtual reference line

Interior search

Value, therefore altogether M bar virtual reference line just has M dimension contrast search;

5.-3, judge whether all virtual reference line satisfy the restrictive condition of speed and power, for n bar virtual reference line, judge whether n bar virtual reference line satisfies condition: $R_n^{t\arg \mathrm{et}}=f_s\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{b}}_n^k$ And $P_n=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{s}_k^n,$ Wherein, n=1 ... M,

Be the targeted rate of n bar virtual reference line, P _nBe the maximum transmit power of n bar virtual reference line,, then adjust first Lagrange multiplier of n bar virtual reference line if n bar virtual reference line does not satisfy condition

With second Lagrange multiplier

, and return execution in step 5.-2; If n bar virtual reference line satisfies condition, then re-execute step and continue 5.-3 to judge whether next bar virtual reference line satisfies condition, when all satisfying condition, all virtual reference line finish execution in step 5.;

Each bar virtual reference line distributed the transmitted power that obtains transmitted power,, n bar virtual reference line is distributed the transmitted power that obtains on each subcarrier for n bar virtual reference line as each bar twisted-pair feeder in the alternative separately group $s^n=[s_1^n,\&CenterDot;\&CenterDot;\&CenterDot;s_k^n,\&CenterDot;\&CenterDot;\&CenterDot;,s_K^n]$ The n that substitutes as this virtual reference line organizes the interior transmitted power of each bar twisted-pair feeder on each subcarrier $s^{l_n}=[s_1^{l_n},\&CenterDot;\&CenterDot;\&CenterDot;s_k^{l_n},\&CenterDot;\&CenterDot;\&CenterDot;,s_K^{l_n}]\text{,}$ Wherein, k=1 ..., K, K represent the sum of subcarrier,

Be the transmitted power of n bar virtual reference line on the k subcarrier,

Be the interior transmitted power of each bar twisted-pair feeder on the k subcarrier of n group that n bar virtual reference line substitutes.

Above-mentioned steps is adjusted first Lagrange multiplier of n bar virtual reference line in 5.-3

With second Lagrange multiplier

First kind of computational process be: defining adjusted first Lagrange multiplier is

, define adjusted first Lagrange multiplier and be

, ${\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n\&prime;={[{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n+\mathrm{\&epsiv;}(R_n^{t\arg \mathrm{et}}-R_n)]}^{+},$ ${\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n\&prime;={[{\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n+\mathrm{\&epsiv;}(\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{s}_k^n-P_n)]}^{+},$ Wherein, ε is a step factor,

Be the targeted rate of n bar virtual reference line, R _nBe the transmission rate of n bar virtual reference line, $R_n=f_s\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{b}}_n^k,$ P _nBe the maximum transmit power of n bar virtual reference line,

Be the transmitted power of n bar virtual reference line on k subcarrier,

Be the maximum number bits that can load of n bar virtual reference line on k subcarrier, f _sBe character rate; With adjusted first Lagrange multiplier

Assignment is given

,

=

, with adjusted second Lagrange multiplier

Assignment is given

,

=

This method of adjustment, the result who makes the contrast search obtain is comparatively accurate.

Above-mentioned steps is adjusted first Lagrange multiplier of n bar virtual reference line in 5.-3

With second Lagrange multiplier

Second kind of computational process be: defining adjusted first Lagrange multiplier is

, define adjusted first Lagrange multiplier and be

, $\left[\begin{array}{c}{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n\&prime;\\ {\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n\&prime;\end{array}\right]={(\left[\begin{array}{c}{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n\\ {\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n\end{array}\right]-\mathrm{\&epsiv;}\left[\begin{array}{c}{R}_n-R_n^{t\arg \mathrm{et}}\\ P_n-\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{s}_k^n\end{array}\right])}^{+},$ Wherein, ε is a step factor, R _nBe the transmission rate of n bar virtual reference line, $R_n=f_s\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{b}}_n^k,$

Be the targeted rate of n bar virtual reference line, P _nBe the maximum transmit power of n bar virtual reference line,

Be the transmitted power of n bar virtual reference line on k subcarrier,

Be the maximum number bits that can load of n bar virtual reference line on k subcarrier, f _sBe character rate; With adjusted first Lagrange multiplier

Assignment is given

,

=

, with adjusted second Lagrange multiplier

Assignment is given

,

=

The convergence rate of this method of adjustment will be far away faster than first kind of method of adjustment, but the operand of this method of adjustment is littler than first kind of method of adjustment.

At this, the computation complexity of iteration water-filling method, desirable spectrum management method and the inventive method is compared, as shown in table 1, N represents the twisted-pair feeder sum in the table 1, M represents total number packets.

The computation complexity comparison sheet of table 1 iteration water-filling method, desirable spectrum management method and the inventive method

Can find from table 1: the computation complexity of the inventive method is between iteration water-filling method and desirable spectrum management method, and when N and M differ bigger, the computation complexity of the inventive method approaches the iteration water-filling method, and the performance of the inventive method will obviously be better than the iteration water-filling method.In order to prove the correctness of above theory, below our emulation compared the performance of this several method.

The emulation that the present invention provides is based on the measured data that is provided by France Telecomm (research and development department of France Telecom).These group data are that 600m, 300m, 150m, 75m form by length respectively, and the channel fading of every kind of length and cross-talk have 28 * 28 groups of data compositions, frequency by 0.01MHz to 30MHz.The network topology structure that adopts in the emulation as shown in Figure 3.The hypothetical target error rate is 10 ^-7, coding gain and noise margin are respectively 3dB and 6.8dB, and sub-carrier frequency separation and character rate are respectively 4.3125KHz and 4KHz, and the power of white Gaussian noise is-140dBm that the VDSL2 spectrum mask is-60dBm.Because when N=8, the computation complexity of desirable spectrum management method suitable greatly, the existing calculator memory in laboratory can't satisfy its demand, so we have only provided the simulation result of iteration water-filling method and the inventive method.Fig. 4, Fig. 5 and Fig. 6 have provided the rate domain of these two kinds of methods when the L among Fig. 3 (m) is 75m, 150m and 300m respectively.As can be seen, the performance of the inventive method obviously is better than the iteration water-filling method from Fig. 4, Fig. 5 and Fig. 6.Therefore, method of the present invention is practicable.

Claims (3)

1, a kind of dynamic spectrum management method that reduces the Digital Subscriber Line cross-talk is characterized in that may further comprise the steps:

1. according to the channel transfer characteristic of twisted-pair feeder, many twisted-pair feeders in the bunch of cables in the multi-user DSL system are divided into the M group, r are arranged in every group _nBar has the twisted-pair feeder of same channel transmission characteristic, and the set of every group of all interior twisted-pair feeders is expressed as L _n={ l _n(1) ..., l _n(r _n), wherein, n=1 ..., M, l _n(1) the 1st twisted-pair feeder in the expression n group, l _n(r _n) the interior r of expression n group _nBar twisted-pair feeder, each the bar twisted-pair feeder in every group have from crosstalking except that the group of other twisted-pair feeders self in same group, and each interior bar twisted-pair feeder of each group has from other does not crosstalk between the group of interior twisted-pair feeder on the same group;

2. to each the bar twisted-pair feeder allocation of transmit power on K subcarrier in each group, wherein to the r in the n group _nThe bar twisted-pair feeder distributes identical transmitted power on k subcarrier

Obtain the bit number of p bar twisted-pair feeder on k subcarrier in the n group

Wherein, Γ is a signal to noise ratio difference, l _n(p) the p bar twisted-pair feeder in the expression n group, p=1 ..., r _n, k=1 ..., K, K represent the sum of subcarrier, N represents number of users,

The impulse response of representing the fading channel of p bar twisted-pair feeder on k subcarrier in the n group,

Represent to crosstalk in the group that the q bar twisted-pair feeder in the n group forms on k subcarrier the p bar twisted-pair feeder in the n group,

Represent that m organizes interior q bar twisted-pair feeder the p bar twisted-pair feeder in the n group is crosstalked between the group that forms on k the subcarrier,

Represent the noise power of p bar twisted-pair feeder on k subcarrier in the n group;

3. calculate the average channel transmission characteristic of all twisted-pair feeders on each subcarrier in each group respectively, introduce the corresponding virtual reference line according to the average channel transmission characteristic, calculate the fading channel and the crosstalk channels of virtual reference line, calculate the virtual transmission model of virtual reference line again according to fading channel and crosstalk channels, wherein on k subcarrier, calculate the average channel transmission characteristic of all twisted-pair feeders on k subcarrier in each group, introduce corresponding M bar virtual reference line according to the average channel transmission characteristic, for n bar virtual reference line, its fading channel on k subcarrier is

${\stackrel{\&OverBar;}{h}}_{k,\mathrm{direct}}^{n,n}=\frac{1}{r_n}\underset{p=1}{\overset{r_n}{\mathrm{\&Sigma;}}}\left|h_k^{l_n\left(p\right),l_n\left(p\right)}\right|,$ Wherein, n=1 ... M, k=1 ..., K, K represent the sum of subcarrier, l _n(p) the p bar twisted-pair feeder in the expression n group, Represent the impulse response of the fading channel of p bar twisted-pair feeder on k subcarrier in the n group, its crosstalk channels on k subcarrier is

${\stackrel{\&OverBar;}{h}}_{k,\mathrm{crosstalk}}^{n,m}=\left\{\begin{array}{c}\frac{1}{r_n}\underset{p=1}{\overset{r_n}{\mathrm{\&Sigma;}}}\underset{q=1,q\&NotEqual;p}{\overset{r_m}{\mathrm{\&Sigma;}}}\left|h_k^{l_n\left(p\right),l_m\left(q\right)}\right|,n=m\\ \frac{1}{r_n}\underset{p=1}{\overset{r_n}{\mathrm{\&Sigma;}}}\underset{q=1}{\overset{r_m}{\mathrm{\&Sigma;}}}\left|h_k^{l_n\left(p\right),l_m\left(q\right)}\right|,n\&NotEqual;m\end{array}\right.,$ Wherein, n=1 ... M, m=1 ... M,

Represent that m organizes interior q bar twisted-pair feeder the p bar twisted-pair feeder in the n group is crosstalked between the group that forms on k the subcarrier; Fading channel according to n bar virtual reference line

And crosstalk channels

Calculate the virtual transmission model of n bar virtual reference line on k subcarrier ${\stackrel{\&OverBar;}{y}}_k^n={\stackrel{\&OverBar;}{h}}_{k,\mathrm{drect}}^{n,n}{x}_k^n+\underset{m=1}{\overset{M}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{h}}_{k,\mathrm{crosstalk}}^{n,m}{x}_k^m+z_k^n,$ Wherein,

Represent the transmission signal of n bar virtual reference line on k subcarrier,

Represent the transmission signal of m bar virtual reference line on k subcarrier,

Represent the white Gaussian noise of n bar virtual reference line on k subcarrier; Every virtual reference line has from the alien cross-talk except that other virtual reference line self, each bar virtual reference line has simultaneously from crosstalking, the mean value of crosstalking in the group that this value of crosstalking certainly has for all twisted-pair feeders in the group that is substituted by this virtual reference line;

4. according to the virtual transmission model of each bar virtual reference line on each subcarrier, calculate the maximum number bits that each bar virtual reference line can load on each subcarrier, wherein to n bar virtual reference line, according to the virtual transmission model of n bar virtual reference line on k subcarrier

Obtaining the maximum number bits that can load of n bar virtual reference line on k subcarrier is ${\stackrel{\&OverBar;}{b}}_k^n={\log }_2(1+\frac{1}{\mathrm{\&Gamma;}}\frac{{\left|{\stackrel{\&OverBar;}{h}}_{k,\mathrm{drect}}^{n,n}\right|}^2{s}_k^n}{\underset{m=1}{\overset{M}{\mathrm{\&Sigma;}}}{\left|{\stackrel{\&OverBar;}{h}}_{k,\mathrm{crosstalk}}^{n,m}\right|}^2{s}_k^m+{\mathrm{\&sigma;}}_k^n}),$ Wherein, Γ is a signal to noise ratio difference, Represent the transmitted power of n bar virtual reference line on k subcarrier,

Represent the transmitted power of m bar virtual reference line on k subcarrier,

Be the noise power of n bar virtual reference line on k subcarrier;

5. be each bar virtual reference line allocation of transmit power, detailed process is: 5.-1, for all virtual reference line, and initialization first Lagrange multiplier With second Lagrange multiplier $\stackrel{\&OverBar;}{\mathrm{\&lambda;}}=[{\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_1,...,{\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_M];$ 5.-2, calculate the transmitted power of all virtual reference line on all subcarriers, on k subcarrier, carry out M dimension contrast search, obtain the transmitted power of all virtual reference line on k subcarrier, $s_k^1,...,s_k^M=\arg \underset{s_k^1,...,s_k^M}{\max }{\stackrel{\&OverBar;}{J}}_k,$ Wherein,

Be the Lagrangian of all virtual reference line on k subcarrier, ${\stackrel{\&OverBar;}{J}}_k=\underset{n=1}{\overset{M}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n{f}_s{\stackrel{\&OverBar;}{b}}_k^n-\underset{n=1}{\overset{M}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n{s}_k^n,$ K=1 ..., K, K represent the sum of subcarrier, f _sBe character rate,

Be the maximum number bits that can load of n bar virtual reference line on k subcarrier,

Be the transmitted power of n bar virtual reference line on k subcarrier; 5.-3, judge whether all virtual reference line satisfy the restrictive condition of speed and power, for n bar virtual reference line, judge whether n bar virtual reference line satisfies condition: $R_n^{t\arg \mathrm{et}}=f_s\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{b}}_n^k$ And $P_n=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{s}_k^n,$ Wherein, n=1 ... M, Be the targeted rate of n bar virtual reference line, P _nBe the maximum transmit power of n bar virtual reference line,, then adjust first Lagrange multiplier of n bar virtual reference line if n bar virtual reference line does not satisfy condition

With second Lagrange multiplier

, and return execution in step 5.-2; If n bar virtual reference line satisfies condition, then re-execute step and continue 5.-3 to judge whether next bar virtual reference line satisfies condition, when all satisfying condition, all virtual reference line finish execution in step 5.;

6. the transmitted power that each bar virtual reference line distribution is obtained for n bar virtual reference line, on each subcarrier is distributed the transmitted power that obtain with n bar virtual reference line as the transmitted power of each bar twisted-pair feeder in the group that substitutes separately $s^n=[s_1^n,\&CenterDot;\&CenterDot;\&CenterDot;s_k^n,\&CenterDot;\&CenterDot;\&CenterDot;,s_K^n]$ The n that substitutes as this virtual reference line organizes the interior transmitted power of each bar twisted-pair feeder on each subcarrier $s^{l_n}=[s_1^{l_n},\&CenterDot;\&CenterDot;\&CenterDot;s_k^{l_n},\&CenterDot;\&CenterDot;\&CenterDot;,s_K^{l_n}]\text{,}$ Wherein, k=1 ..., K, K represent the sum of subcarrier,

Be the transmitted power of n bar virtual reference line on the k subcarrier,

Be the interior transmitted power of each bar twisted-pair feeder on the k subcarrier of n group that n bar virtual reference line substitutes.

2, a kind of dynamic spectrum management method that reduces the Digital Subscriber Line cross-talk according to claim 1 is characterized in that during described step 5.-3 adjusting first Lagrange multiplier of n bar virtual reference line

With second Lagrange multiplier

Computational process be: defining adjusted first Lagrange multiplier is

, define adjusted first Lagrange multiplier and be

, ${\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n\&prime;={[{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n+\mathrm{\&epsiv;}(R_n^{t\arg \mathrm{et}}-R_n)]}^{+},$ ${\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n\&prime;={[{\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n+\mathrm{\&epsiv;}(\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{s}_k^n-P_n)]}^{+},$ Wherein, ε is a step factor,

Be the targeted rate of n bar virtual reference line, R _nBe the transmission rate of n bar virtual reference line, $R_n=f_s\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{b}}_n^k,$ P _nBe the maximum transmit power of n bar virtual reference line, Be the transmitted power of n bar virtual reference line on k subcarrier,

Be the maximum number bits that can load of n bar virtual reference line on k subcarrier, f _sBe character rate; With adjusted first Lagrange multiplier

Assignment is given

,

=

, with adjusted second Lagrange multiplier

Assignment is given

,

=

3, a kind of dynamic spectrum management method that reduces the Digital Subscriber Line cross-talk according to claim 1 is characterized in that during described step 5.-3 adjusting first Lagrange multiplier of n bar virtual reference line

With second Lagrange multiplier

Computational process be: defining adjusted first Lagrange multiplier is

, define adjusted first Lagrange multiplier and be

, $\left[\begin{array}{c}{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n\&prime;\\ {\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n\&prime;\end{array}\right]={(\left[\begin{array}{c}{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_n\\ {\stackrel{\&OverBar;}{\mathrm{\&lambda;}}}_n\end{array}\right]-\mathrm{\&epsiv;}\left[\begin{array}{c}{R}_n-R_n^{t\arg \mathrm{et}}\\ P_n-\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{s}_k^n\end{array}\right])}^{+},$ Wherein, ε is a step factor, and Rn is the transmission rate of n bar virtual reference line, $R_n=f_s\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{\stackrel{\&OverBar;}{b}}_n^k,$

Be the targeted rate of n bar virtual reference line, P _nBe the maximum transmit power of n bar virtual reference line,

Be the transmitted power of n bar virtual reference line on k subcarrier, Be the maximum number bits that can load of n bar virtual reference line on k subcarrier, f _sBe character rate; With adjusted first Lagrange multiplier

Assignment is given

,

=

, with adjusted second Lagrange multiplier

Assignment is given

,

=

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