CN102780511B - Echo canceller, data transmission system and echo cancellation method - Google Patents

Echo canceller, data transmission system and echo cancellation method Download PDF

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CN102780511B
CN102780511B CN201210265882.5A CN201210265882A CN102780511B CN 102780511 B CN102780511 B CN 102780511B CN 201210265882 A CN201210265882 A CN 201210265882A CN 102780511 B CN102780511 B CN 102780511B
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delay time
time register
tap
echo
echo canceller
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CN102780511A (en
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俞波
曹炜
魏茂林
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Abstract

An embodiment of the invention provides an echo canceller, a data transmission system and an echo cancellation method. The echo canceller comprises a control module and a filter module. The control module is used for generating first control information according to the number of tapping heads required by the echo canceller. The filter module is used for selecting the tapping heads required to be used by the echo canceller according to the first control information, and echo in the data transmission system is estimated through the selected tapping heads so as to use the estimated echo for canceling the echo in the data transmission system. The control information can be generated according to the number of the tapping heads required to be used by the echo canceller, the tapping heads required to be used by the echo canceller are selected according to the control information so as to enable the echo canceller to be operated by selecting less tapping heads in short line mode, and power consumption of the system is lowered.

Description

The unify method of echo cancelltion of echo canceller, data transmission system
Technical field
The present invention relates to the communications field, especially relate to a kind of the unify method of echo cancelltion of echo canceller, data transmission system.
Background technology
Gigabit Ethernet physical layer (Gigabit Ethernet Physical Layer, GEPHY) is electricity mouthful ethernet physical layer, in five classes or surpass the communication that completes both sides on five class unshielded twisted pairs (Unshielded Twisted Pair, UTP).
According to (the Institute of Electrical and ElectronicsEngineers of IEEE-USA, IEEE) code requirement, the system of 1000Base-T agreement transmits 4D-PAM5 signal with 125MBaud modulation rate on 4 pairs of unshielded twisted pairs, reaches the full-duplex data transmission of 1Gb/s.The length of cable that 1000Base-T supports is wanted to reach 100 meters, and cable transmission speed is as follows: (1) 125M symbol (symbol)/second, 2 bit/symbol; (2) to lead be 250Mb/s to the bit on every pair of line.GEPHY system is used 4D-PAM5 signal, bit error rate (Bit Error Rate, BER) is along with the increase meeting of signal to noise ratio (SignalNoise Ratio, SNR) sharply declines, thereby receiver needs fully to eliminate and to disturb and noise, increase SNR to obtain the less error rate.Meanwhile, at receiver side, must eliminate as far as possible echo (ECHO) signal.
Conventionally, can design the fixedly Adaptive Acoustic Echo Cancellation of exponent number (ECHO canceller) and eliminate echo signal, in long line situation, more than echo canceller may need 150 rank.According to the characteristic of transmission line, the signal delay of 100m line length is approximately 125 symbols; 10m line is approximately 12.5 symbols.Therefore, transmission line for 100m line length, the exponent number of echo canceller needs at least 125 rank, and for the transmission line of 10m, the exponent number of echo canceller only needs 12.5 rank, round numbers is 13 rank, therefore, under short-term pattern, if adopt the echo canceller on 125 rank, can increase the power consumption of echo canceller.
Summary of the invention
A kind of method that embodiments of the invention provide echo canceller, data transmission system to unify echo cancelltion, can reduce the power consumption of echo canceller.
On the one hand, provide a kind of echo canceller, having comprised: control module, has generated the first control information for the number of the tap (tap) that need to use according to this echo canceller; Filtration module, for the tap of selecting this echo canceller to use according to the first control information, and by the echo in selected tap data estimator transmission system, to use the echo in estimated this data transmission system of echo cancelltion going out.
On the other hand, provide a kind of data transmission system, having comprised: local transmitter, for sending data to remote receiver; Local receiver, for receiving data from long-range transmitter; Blender, is connected between this this locality transmitter and this data transmission system transmission line, and is connected between this local receiver and this transmission line; Above-mentioned echo canceller, this echo canceller is connected between this local receiver and this blender, the input of this echo canceller receives the data that this this locality transmitter sends, and this echo estimating is for eliminating the echo of the data of this local receiver reception.
On the other hand, provide a kind of method of echo cancelltion, having comprised: the number of the tap that need to use according to echo canceller has generated the first control information, the tap of the first control information for selecting this echo canceller to use; The tap of selecting this echo canceller to use according to the first control information, by the echo in selected tap data estimator transmission system, to use the echo in estimated this data transmission system of echo cancelltion going out.
The number of the tap that embodiments of the invention can need to be used according to this echo canceller generates control information, and the tap of selecting this echo canceller to use according to this control information, make echo canceller under short-term pattern, to select less tap to carry out work, thereby reduced the power consumption of system.
Term " first " in specification of the present invention and claims and above-mentioned accompanying drawing, " second ", " the 3rd " " 4th " etc. (if existence) are for distinguishing similar object, and needn't be for describing specific order or precedence.The data that should be appreciated that such use suitably can exchanged in situation, so as embodiments of the invention described herein for example can with except here illustrated or otherwise describe those order enforcement.In addition, term " comprises " and " having " and their any distortion, intention is to cover not exclusive comprising, so that the process that comprises a series of unit, method, system, product or equipment are not necessarily limited to those unit, but can comprise clearly do not list or for other intrinsic unit of these processes, method, product or equipment.Fig. 1 is the structural schematic diagram of echo canceller 100 according to an embodiment of the invention.Echo canceller 100 comprises: filtration module 110 and control module 120.
Control module 120, for needing the number of the tap of use to generate the first control information according to echo canceller 100.Filtration module 110, for select echo canceller 100 to need the tap of using according to the first control information, and by the echo in selected tap data estimator transmission system, to use the echo in estimated this data transmission system of echo cancelltion going out.
For example, the line length information that control module 120 can be measured in the training stage according to the communication terminal of data transmission system or the line length information setting in advance or other relevant information determine that echo canceller 100 needs the number of the tap used, and generate the first control information according to the number of definite tap.The first control information is used to indicate filtration module 110 and selects to carry out echo cancelltion with the corresponding tap of number of above-mentioned definite tap.Echo canceller 100 can be digital, also can simulate.Filtration module 110 can for example, be realized by filter (, sef-adapting filter).Data transmission system can be supported the communication under 1000BASE-T consensus standard, and the transmission line of data transmission system can be gigabit Ethernet cable.Embodiments of the invention are not limited to this, and for example, data transmission system also can be supported the agreements such as 100BASE-TX or 10base-T.
The number of the tap that embodiments of the invention can need to be used according to this echo canceller generates control information, and the tap of selecting this echo canceller to use according to this control information, make echo canceller under short-term pattern, to select less tap to carry out work, thereby reduced the power consumption of system.
Fig. 2 is the structural schematic diagram of echo canceller 200 according to another embodiment of the present invention.
Echo canceller 200 comprises: filtration module 210 and control module 220.The filtration module 210 of echo canceller 200 and control module 220 are similar with filtration module 110 and the control module 120 of Fig. 1, at this, suitably omit detailed description.
According to embodiments of the invention, control module 220 determines that according to the line length of the transmission line of this data transmission system this echo canceller 200 needs the number of the tap of use, and according to echo canceller 200, need the number of the tap of use to generate the first control information, wherein the number of determined tap and the line length of this transmission line are directly proportional.
According to embodiments of the invention, control module 220 is also obtained the information of this line length for the training stage before the communicating pair work in this data transmission system from one of this communicating pair.
For example, the training stage of control module 220 before the communicating pair work of this data transmission system (for example, physical layer is controlled PHY control process), from one of this communicating pair, obtain the information of this line length, and according to this line length Information generation control information, this control information is for selecting to need the filter tap of work, and non-selected filter tap does not carry out coefficient update.For example, for the transmission line of 100 line lengths, the exponent number of echo canceller 200 needs at least 125 rank, and for the transmission line of 10m, the exponent number of echo canceller 200 only needs 12.5 rank.Embodiments of the invention are not limited to this, and for example, the number of determined tap also can have with the line length of this transmission line predetermined functional relation.The first control information can adopt the form of bit.For example, in the situation that selector only has a road to input, the first control information is that 1 expression will be inputted as output, and the first control information is that 0 expression is not exported.Alternatively, the first control information can be comprised of a plurality of bits, to can select multichannel input Zhong mono-tunnel input as output.
According to embodiments of the invention, filtration module 210 comprises: the first delay time register group, comprise M the delay time register being connected in series, the input of first delay time register in this M delay time register receives the data of the transmitter transmission of this data transmission system, and the output of this M delay time register is drawn M tap; The second delay time register group, comprises N the delay time register being connected in series, and the output of this N delay time register is drawn N tap; Selector, the input of this selector is connected to this M tap, the output of this selector is connected to the input of first delay time register in the second delay time register group, is connected to the input of first delay time register in the second delay time register group for the tap of selecting K delay time register of this M tap to draw according to the first control information; Multiplier group, comprise N+1 multiplier, the input of this N+1 multiplier is connected respectively to the tap that the output of N tap that the output of this N delay time register draws and K delay time register is drawn, for respectively N+1 data of this N+1 of input multiplier being multiplied by N+1 filter factor; Adder, obtains for the output of cumulative this N+1 multiplier the echo that this estimates, and wherein the number of this definite tap is N+K.
For example, above-mentioned filter factor can be predefined, can be also real-time update.
Filtration module 210 is sef-adapting filter, filtration module 210 also sends the above-mentioned echo estimating to decision device, so that decision device is determined error signal according to the above-mentioned echo estimating, echo canceller 200 also comprises: coefficient updating module 240, and for upgrade this N+1 filter factor according to above-mentioned error signal.
For example, the coefficient updating module 240 of echo canceller 200 can real-time update filter factor.Echo canceller 200 can be implemented as at most the echo canceller on N+M rank, and embodiments of the invention can only upgrade N+1 filter factor under short-term modular, thereby has reduced power consumption.
According to embodiments of the invention, in the situation that control module 220 determines that echo canceller 200 needs the number of the tap of use to be less than or equal to N, control module indicates above-mentioned selector to select the input of first delay time register in the first delay time register group to be connected to the input of first delay time register in the second delay time register group by generating and sending the first control information.
Alternatively, as another embodiment, filtration module 210 comprises: at least one first delay time register group, each delay time register group comprises X the delay time register being connected in series, the output of this X delay time register is drawn X tap, above-mentioned at least one first delay time register group is connected in series, and the input of first delay time register in above-mentioned at least one first delay time register group receives the data of the transmitter transmission of this data transmission system; At least one multiplier group, each multiplier group comprises X multiplier, be respectively used to X data of this X of input multiplier to be multiplied by X filter factor, the input of this X multiplier is connected respectively to the output of this X delay time register, and above-mentioned at least one multiplier group is corresponding with above-mentioned at least one first delay time register group; At least one first adder, is respectively used to the output of cumulative above-mentioned at least one multiplier group, to export at least one first accumulation result; At least one selector, the input of above-mentioned at least one selector is connected respectively to the output of above-mentioned at least one first adder, and above-mentioned at least one selector is for selecting corresponding the first accumulation result according to the first control information from described at least one first accumulated value; Second adder, obtains for output first accumulation result of cumulative above-mentioned at least one selector the echo that this estimates.
Alternatively, as another embodiment, filtration module 210 comprises: the first delay time register group and at least one second delay time register group, each delay time register group comprises X the delay time register being connected in series, the output of this X delay time register is drawn X tap, the first delay time register group and above-mentioned at least one second delay time register group are connected in series, and the input of first delay time register in the first delay time register group receives the data of the transmitter transmission of this data transmission system, at least one selector, above-mentioned at least one selector is connected to the input of above-mentioned at least one the second delay time register group, the tap of above-mentioned at least one selector for selecting the output of above-mentioned at least one the second delay time register group to draw according to the first control information, the first multiplier group and at least one second multiplier group, each multiplier group comprises X multiplier, be respectively used to X data of this X of input multiplier to be multiplied by X filter factor, the input of X multiplier in the first multiplier group is connected respectively to the output of X delay time register in the first delay time register group, the input of X multiplier in each the second multiplier group in above-mentioned at least one second multiplier group is connected respectively to the output of X delay time register in each the second delay time register group in above-mentioned at least one second delay time register group, adder, the data of the tap output that the tap of drawing for the output of cumulative the first delay time register group and the output of selected the second delay time register group are drawn obtain the echo that this estimates.
Alternatively, as another embodiment, filtration module 210 comprises: the first delay time register group, comprise Y the delay time register being connected in series, the input of first delay time register in this Y delay time register receives the data of the transmitter transmission of this data transmission system, and the output of this Y delay time register is drawn Y tap; The first group selector, comprises T selector, and the input of this Y selector is connected respectively to this Y tap, and this Y selector is for selecting S tap of this Y tap according to the first control information; The first multiplier group, comprises Y multiplier, and the input of this T multiplier is connected respectively to the output of this Y selector, is respectively used to Y data of this Y of input multiplier to be multiplied by Y filter factor; Adder, obtains for the output of cumulative this T multiplier the echo that this estimates.
For example, above-mentioned filter factor can be predefined, can be also real-time update.
Alternatively, as another embodiment, filtration module 210 is sef-adapting filter, and filtration module 210 also sends the above-mentioned echo estimating to decision device, so that decision device is determined error signal according to the above-mentioned echo estimating.Echo cancellation module 200 comprises: coefficient updating module 240, for generating the 3rd control information according to the line length of transmission line; According to the 3rd control information selection, need the number of the filter factor of renewal, and upgrade according to error signal the filter factor that this need to upgrade.
For example, in the above-described embodiments, if determine the Echo Canceller that needs 50 rank, coefficient updating module 240 is only upgraded 50 filter factors according to the 3rd control information, can, under short-term modular, can only upgrade less filter factor, thereby reduce power consumption.
This control module 220 is also for generating the second control information according to the line length of this transmission line, the second control information comprises weighted value, wherein this echo canceller 200 also comprises: weighting block 230, be used for receiving the second control information, and the echo that this is estimated is multiplied by this weighted value, wherein this weight and this line length are inversely proportional to.
Embodiments of the invention can be for different line lengths, and the proportion while adjusting echo elimination computing makes the coefficient precision of echo canceller 200 and scope optimum.
The echo canceller 200 of Fig. 2 also comprises: the 3rd delay time register group 250, is connected the delay of being introduced to mate the AFE (analog front end) of the transmitter of described data transmission system with the input of this echo canceller 200.The number of the delay time register in the 3rd delay time register group 250 depends on the delay that the AFE (analog front end) of the transmitter of this data transmission system is introduced.
Embodiments of the invention can arrange at the entrance of echo canceller 200 delay time register group, by selecting the number of delay cell, adjust the delay of transmission symbol (TX Symbol) in echo canceller 200, so that exact matching simulation sends the delay that front end is introduced.
According to embodiments of the invention, provide a kind of data transmission system, having comprised: local transmitter, for sending data to remote receiver; Local receiver, for receiving data from long-range transmitter; Blender, is connected between this this locality transmitter and the transmission line of this data transmission system, and is connected between this local receiver and this transmission line; The echo canceller 200 of Fig. 1 echo canceller 100 or Fig. 2, this echo canceller is connected between this local receiver and this blender, the input of this echo canceller receives the data that this this locality transmitter sends, and this echo estimating is for eliminating the echo of the data of this local receiver reception.
For example, echo canceller can be independently to install, and also can be arranged on local receiver.
Fig. 3 is the structural schematic diagram of echo canceller 300 according to another embodiment of the present invention.Echo canceller 300 is examples of the echo canceller 200 of Fig. 2.
Echo canceller 300 comprises: filtration module 310, control module 320, weighting block 330 and coefficient updating module 340.
Control module 320 is for needing the number of the tap of use to generate the first control information according to echo canceller 300.For example, the training stage before the communicating pair work of data transmission system, control module 320 is obtained the line length information of transmission line from one of communicating pair.
Particularly, in physical layer control procedure, two communication terminals when training through consultation mode obtain line length information, for example, the first communication terminal sends a signal to second communication terminal, second communication terminal receives backward the first communication terminal of this signal and returns to response, and the first communication terminal can be known the time difference between the moment that sends the moment of this signal and receive this response.Because electromagnetic speed is identical with the light velocity, therefore, can obtain line length information according to this time difference.Embodiments of the invention are not limited to this, also can adopt alternate manner to obtain line length information, for example, can preset line length information according to the first known communication terminal and the distance between second communication terminal.
After having determined line length information, control module 320 can determine that echo canceller 300 needs the number of the tap of use according to line length information, and wherein the number of determined tap and the line length of transmission line are directly proportional.For example, according to the characteristic of transmission line, the signal delay of 100m line length is approximately 125 symbols, and 10m line is approximately 12.5 symbols.Therefore, when line length is 100m, the exponent number of echo canceller 300 (corresponding to the exponent number of sef-adapting filter) needs at least 125 rank, and line length is 10m) time, the exponent number of echo canceller 300 only needs 12.5 rank, and round numbers is 13 rank.The exponent number that echo canceller 300 needs the number of the tap of use to need corresponding to echo canceller 300.
Determine echo canceller 300 exponent numbers of needs or the number of tap according to line length information after, control module 320 can generate the first control information according to the number of determined tap, and the first control information selects corresponding tap to carry out echo cancelltion for controlling the tap number that filtration module 310 uses as required.The first control information can be mask, for example ... 00001000000000 ..., wherein in the present embodiment, totally 129,0 ~ 128.This mask is for making filtration module 310 select corresponding tap for echo cancelltion according to each value of this mask.In embodiments of the present invention, the number of the tap that control module 320 is definite is 30+K, and the value of the K position of mask is 1, and the value of other of mask is 0, for example, when needs 50 rank, K=20.
Filtration module 310 comprises the first delay time register group 311, the second delay time register group 312, selector 313, multiplier group 314 and adder 315.
The first delay time register group 311 comprises 128 delay time registers that are connected in series, the data that the transmitter of the input receiving data transmission system of first delay time register D in the first delay time register group 311 sends, wherein the output of 128 delay time register D is drawn 128 taps.The second delay time register group 312 comprises 30 delay time register D that are connected in series, and wherein the output of 30 delay time register D is drawn 30 taps.According to embodiments of the invention, be not limited to this, the first delay time register group 311 and the second delay time register group 312 also can comprise the delay time register of other number, for example, the first delay time register group can comprise 150 delay time registers, the second delay time register group can comprise 50 delay time registers, etc.
The input of selector 313 is connected to 128 taps of the first delay time register group 311, and the output of selector 313 is connected to the input of first delay time register D in the second delay time register group 312.Selector 313 (for example can receive control information that control module 320 sends, mask), the tap of selecting K delay time register D in 128 taps in the first delay time register group 311 to draw is connected to the input (for example, the value of the K position of mask is 1) of first delay time register D in the second delay time register group 312.The filtering operation and the factor updating operation that by the output valve of K delay time register D and the output valve of the second delay time register group 312, have been used for echo cancelltion.For example, when training, control module 320 is learnt the echo canceller that needs 50 rank according to line length, utilize the first control information to select the 20th rank in the first delay time register group 311 to export the input as the second delay time register group, through 30 rank outputs of the second delay time register group 312, jointly realize the filtering operation on 50 rank again.
Especially, in control module 320, determine that echo canceller 300 needs the number of the tap of use (to be for example less than or equal to 30, the line length of transmission line is less than or equal to 24m) situation under, control module 320 sends the first control information to selector, the tap that indication selector selects the output of first delay time register D in the first delay time register group 311 to draw is connected to the input (for example, the value of the 0th of mask the is 1) of first delay time register D in the second delay time register group 312.
Multiplier group 314, comprise 30+1=31 multiplier, the input correspondence of 30 multipliers in above-mentioned 31 multipliers is connected to 30 taps that the output of 30 delay time register D in the second delay time register group 312 is drawn, the tap that the output that another multiplier is connected to above-mentioned K delay time register is drawn, above-mentioned 31 multipliers receive the filter factor (C after coefficient updating module is upgraded i, C i+1..., C i+N, in the present embodiment, N=30), be respectively used to the data symbol of the above-mentioned 30+1 of an input multiplier to be multiplied by 30+1 filter factor.
Adder 315, the echo signal that the echo canceller 300 of exporting for cumulative above-mentioned 30+1 multiplier estimates, and the echo signal estimating is outputed to weighting block 330.
Control module 320 is also for generating the second control information according to the line length of transmission line, and the second control information comprises weighted value.The second control information that comprises weighted value that weighting block 330 sends for receiving control module 320, receive the echo signal estimating of adder 315 outputs, and the echo signal estimating is multiplied by this weighted value, and this weighted value is inversely proportional to the line length of above-mentioned transmission line or becomes predetermined functional relation.The second control information (ratio_ctrl) is for regulating the proportion of filter factor, according to the difference of line length, echo signal can be used different weight coefficients when eliminating, to guarantee that filter coefficient obtains maximum dynamic range, thus the precision of raising coefficient.Because line length is different, the power of echo signal is also different, and like this, the difference of the filter coefficient value that different line lengths are corresponding is larger; By regulating the ratio of this echo signal, the coefficient value of the filter in the time of can allowing different line length is in a relatively consistent scope; For example, in the PHY control stage, if be defined as transmission line, be long line, weighting controlling value is set to 1/2.Weighting block 330 for example can be realized by multiplier.
The output of weighting block 330 (is the output of echo canceller 300, ec_out_data) with forward equalizer (the Feed Forward Equalizer of data transmission system, FFE) output signal (ffe_data_out) is added and obtains signal ffe_ec_dat, the output signal (dfe_data_out) of signal ffe_ec_dat and feedback equalizer (Decision Feed Back Equalizer, DFE) is added and obtains signal r k, signal r koutput to decision device and obtain signal d kand error signal (sli_e), this error signal is imported into coefficient updating module 340 and carries out factor updating operation.Decision device, FFE equalizer and DFE equalizer are routine techniques, do not repeat them here.
Coefficient updating module 340 can adopt lowest mean square (Least mean square, LMS) coefficient update algorithm, and for example, the coefficient update formula based on LMS is C k+1 i=C k i+ α * sli_e*sgn (ec_data_in), wherein, C k irepresent k i rank coefficient constantly, C k+1 irepresent k+1 i rank coefficient constantly, α is coefficient update step-length; Symbol manipulation is got in sgn representative; After tap through mask (mask) signal selection echo canceller, only have the second delay time register group to participate in filtering operation, meanwhile, the coefficient that only need to upgrade participation filtering operation (is coefficient C i, C i+1..., C i+N), for example, in the present embodiment, even also only need to upgrade 31 coefficients under long ray mode.
Echo canceller 300 also comprises the 3rd delay time register group (Z^-m) 350.The 3rd delay time register group 350 can be in series by m delay time register, the number m of the delay time register in the 3rd delay time register group depends on the delay that the AFE (analog front end) of the transmitter of data transmission system is introduced, by selecting the number m of delay time register in the 3rd delay time register group can adjust the delay of the data symbol (Symbol) of echo canceller 300 receptions, with exact matching simulation, send the delay that front end is introduced.The 3rd delay time register group 350 can be connected to the input (or entrance) of echo canceller 300, is connected between the transmitter and filtration module 310 of data transmission system.The data symbol that the transmitter of the 3rd delay time register group 350 receiving data transmission systems sends (for example, TX_data) as the input data symbol of filtration module 310 (for example, ec_data_in), and by the data symbol after postponing send to filtration module 310.
Fig. 4 is the structural schematic diagram of echo canceller 400 according to another embodiment of the present invention.Echo canceller 400 is examples of the echo canceller 200 of Fig. 2.
Echo canceller 400 comprises: filtration module 410, control module 420, weighting block 430 and coefficient updating module 440.
Control module 420 is for needing the number of the tap of use to generate the first control information according to echo canceller 400.Control module 420 determines that the method for number of the tap that echo canceller 400 need to use is identical with the control module of Fig. 3 320, does not repeat them here.
Determine echo canceller 400 taps of needs or the number of exponent number according to line length information after, control module 420 can generate the first control information according to the number of determined tap, and the first control information selects corresponding tap to carry out echo cancelltion for controlling the tap number that filtration module 410 uses as required.Different from the control module of Fig. 3, the control module 420 of Fig. 4 drives different selectors by the first control information, to select different taps to carry out echo cancelltion.Referring to Fig. 4, control module 420 is controlled selector 417 and is selected different taps with selector 419.
Filtration module 410 comprises that the first delay time register group 411, second group postpone to deposit the 412, first multiplier group 413, the second multiplier group 414, first adder 415, second adder 416, selector 417, selector 419 and the 3rd adder 418.The tap that the output of the first delay time register group 411 is drawn is connected to the tap that the output of the first multiplier group 413, the second delay time register groups 412 draws and is connected to the second multiplier group 414.The output of the first multiplier group 413 is connected to the input of first adder 415, and the output of the second multiplier group 414 is connected to the input of second adder 416.The data that the transmitter of the input receiving data transmission system of first delay time register D in the first delay time register group 411 sends.Each delay time register group can comprise the delay time register D of similar number, and the delay time register in each delay time register group is connected in series, and the first delay time register group 411 and second group postpone to deposit 412 and be connected in series.The output of first adder 415 is connected to the 3rd adder 418 through first selector 417, and the output of second adder 416 is connected to the 3rd adder 418 through second selector 419.First selector 417 and second selector 419 are subject to the driving of the first control information.
For example, suppose that echo canceller 400 has 150 delay time registers, the first delay time register group 411 and second postpones to deposit 412 and respectively comprises 75 delay time registers that are connected in series.When control module 420, determine need to be less than the echo canceller on 75 rank time, send the first control information to selector 417 and selector 419, make respectively selector 417 conductings and selector 419 is turn-offed, like this, participate in 75 taps of only having of filtering operation.When control module 420, determine need to be greater than the echo canceller on 75 rank time, send the first control information to selector 417 and selector 419, make selector 417 and the equal conducting of selector 419, the tap that participates in like this computing is 150.
Weighting block 430 is similar with the weighting block 330 of Fig. 3, does not repeat them here.Different from the embodiment of Fig. 3, weighting block 430 receives the output of adder 418.
Coefficient updating module 440 can adopt lowest mean square (Least mean square, LMS) coefficient update algorithm, and for example, the coefficient update formula based on LMS is C k+1 i=C k i+ α * sli_e*sgn (ec_data_in), wherein, C k irepresent k i rank coefficient constantly, C k+1 irepresent k+1 i rank coefficient constantly, α is coefficient update step-length, symbol manipulation is got in sgn representative, control the tap of selector 417 and selector 419 selection echo cancellers through the first control information after, can only have part or all of tap to participate in filtering operation, simultaneously, only need to upgrade the coefficient that participates in filtering operation, for example, in the present embodiment, when control module 420 is determined need to be less than the echo canceller on 75 rank time, only need to upgrade 75 filter factors, in this case, 75 filter factors are only upgraded in the 3rd control information that coefficient updating module 440 sends according to control module 420, for example, the 3rd control information can only need to be upgraded the information of 75 filter factors for indication, after coefficient updating module 440 receives the first control information, the filter factor that does not need to upgrade can be set to 0 or do not export these filter factors.
Further, echo canceller 400 also comprises the 3rd delay time register group (Z^-m) 450.The 3rd delay time register group 450 is similar with the 3rd delay time register group 450 of Fig. 3, does not repeat them here.
Should be understood that at least one delay time register group of can also connecting between the first delay time register group 411 and the second delay time register group 412.For example, filtration module 410 can comprise three delay time register groups, i.e. a delay time register group between the first delay time register group 411, the second delay time register group 412 and the first delay time register group 411 and the second delay time register group 412.The tap of drawing from each delay time register group output is connected to multiplier group, and the output of each multiplier group is connected to the input of an adder.These adders are connected to another adder through the selector of being controlled by control module 420, and the echo signal being gone out by this another adder output estimation is to weighting block 430.Each delay time register group can comprise the delay time register D of similar number, and in each delay time register group, delay time register is connected in series, and each delay time register group is connected in series.
Fig. 5 is the structural schematic diagram of echo canceller 500 according to another embodiment of the present invention.Echo canceller 500 is examples of the echo canceller 200 of Fig. 2.
Echo canceller 500 comprises: filtration module 510, control module 520, weighting block 530 and coefficient updating module 540.
Control module 520 is for needing the number of the tap of use to generate the first control information according to echo canceller 500.Control module 520 determines that the method for number of the tap that echo canceller 500 need to use is identical with the control module of Fig. 3 320, does not repeat them here.
Determine echo canceller 500 taps of needs or the number of exponent number according to line length information after, control module 520 can generate the first control information according to the number of determined tap, and the first control information selects corresponding tap to carry out echo cancelltion for controlling the tap number that filtration module 510 uses as required.Different from the control module 320 of Fig. 3, the control module 520 of Fig. 5 drives selector by the first control information, to select different taps to carry out echo cancelltion.Referring to Fig. 5, control module 520 is controlled selector 516 and is selected different taps.
Filtration module 510 comprises that the first delay time register group 511, second group postpone to deposit the 512, first multiplier group 513, the second multiplier group 514, adder 515, selector 516.The tap that the output of the first delay time register group 511 is drawn is connected to the tap that the output of the first multiplier group 513, the second delay time register groups 512 draws and is connected to the second multiplier group 514.The output of the output of the first multiplier group 513 and the second multiplier group 514 is connected to the input of adder 515.The data that the transmitter of the input receiving data transmission system of first delay time register D in the first delay time register group 511 sends.Each delay time register group can comprise the delay time register D of similar number, and the delay time register in each delay time register group is connected in series, and the first delay time register group 511 and second group postpone to deposit 512 and be connected in series.First selector 515 is subject to the driving of the first control information.
For example, suppose that echo canceller 500 has 150 delay time registers, the first delay time register group 511 and second postpones to deposit 512 and respectively comprises 75 delay time registers that are connected in series.When control module 520, determine need to be less than the echo canceller on 75 rank time, send the first control information to selector 516, selector 516 is turn-offed, like this, participate in 75 taps of only having of filtering operation.When control module 520, determine need to be greater than the echo canceller on 75 rank time, send the first control information to selector 516, make selector 516 conductings, the tap that participates in like this computing is 150.
Weighting block 530 is similar with the weighting block 330 of Fig. 3, does not repeat them here.Different from the embodiment of Fig. 3, the output of adder 515 is connected to the input of weighting block 530.
Coefficient updating module 540 can adopt lowest mean square (Least mean square, LMS) coefficient update algorithm, and for example, the coefficient update formula based on LMS is C k+1 i=C k i+ α * sli_e*sgn (ec_data_in), wherein, C k irepresent k i rank coefficient constantly, C k+1 irepresent k+1 i rank coefficient constantly, α is coefficient update step-length, symbol manipulation is got in sgn representative, control the tap of selector 516 selection echo cancellers through the first control information after, can only have part or all of tap to participate in filtering operation, simultaneously, only need to upgrade the coefficient that participates in filtering operation, for example, in the present embodiment, when control module 520 is determined need to be less than the echo canceller on 75 rank time, only need to upgrade 75 coefficients, in this case, 75 filter factors are only upgraded in the 3rd control information that coefficient updating module 540 sends according to control module 520, for example, the 3rd control information can only need to be upgraded the information of 75 filter factors for indication, after coefficient updating module 540 receives the first control information, the filter factor that does not need to upgrade can be set to 0 or do not export these filter factors.
Further, echo canceller 500 also comprises the 3rd delay time register group (Z^-m) 550.The 3rd delay time register group 550 is similar with the 3rd delay time register group 550 of Fig. 3, does not repeat them here.
Should understand, at least one delay time register group of can also connecting between the first delay time register group 511 and the second delay time register group 512, between two adjacent delay time register groups, can connect selector, these selectors receive the control of control modules 520, to select not tap on the same group to participate in filtering operation.For example, filtration module 510 can comprise three delay time register groups, i.e. a delay time register group between the first delay time register group 511, the second delay time register group 512 and the first delay time register group 511 and the second delay time register group 512.The tap of drawing from each delay time register group output is connected to a multiplier group, and the output of all multipliers is connected to the input of adder 515.Each delay time register group can comprise the delay time register D of similar number, and in every delay time register group, delay time register is connected in series, and every delay time register group is connected in series.
Fig. 6 is the structural schematic diagram of echo canceller 600 according to another embodiment of the present invention.Echo canceller 600 is examples of the echo canceller 200 of Fig. 2.
Echo canceller 600 comprises: filtration module 610, control module 620, weighting block 630 and coefficient updating module 640.
Control module 620 is for needing the number of the tap of use to generate the first control information according to echo canceller 600.Control module 620 determines that the method for number of the tap that echo canceller 600 need to use is identical with the control module of Fig. 3 320, does not repeat them here.
Determine echo canceller 600 taps of needs or the number of exponent number according to line length information after, control module 620 can generate the first control information according to the number of determined tap, and the first control information selects corresponding tap to carry out echo cancelltion for controlling the tap number that filtration module 610 uses as required.Different from the control module 320 of Fig. 3, the control module 620 of Fig. 6 drives different selectors by the first control information, to select different taps to carry out echo cancelltion.Referring to Fig. 6, control module 620 is controlled selector group 612 and is selected different taps.
Filtration module 610 comprises the first delay time register group 611, multiplier group 613, adder 614, selector group 612.The tap that the output of the first delay time register group 611 is drawn is connected to the first multiplier group 613.The output of multiplier group 613 is connected to the input of adder 614.The data that the transmitter of the input receiving data transmission system of first delay time register D in the first delay time register group 611 sends.Delay time register in the first delay time register group is connected in series.Selector group 612 is subject to the driving of the first control information.
For example, suppose that echo canceller 600 has 150 delay time registers.When control module 620, determine need to be less than the echo canceller on 75 rank time, send the first control information to selector group 613, make front 75 selector conductings, rear 75 selectors turn-off, and like this, participate in 75 taps of only having of filtering operation.
Weighting block 630 is similar with the weighting block 330 of Fig. 3, does not repeat them here.Different from the embodiment of Fig. 3, the output of adder 614 is connected to the input of weighting block 630.
Coefficient updating module 640 can adopt lowest mean square (Least mean square, LMS) coefficient update algorithm, and for example, the coefficient update formula based on LMS is C k+1 i=C k i+ α * sli_e*sgn (ec_data_in), wherein, C k irepresent k i rank coefficient constantly, C k+1 irepresent k+1 i rank coefficient constantly, α is coefficient update step-length, symbol manipulation is got in sgn representative, control the tap of selector group 612 selection echo cancellers through the first control information after, can only have part or all of tap to participate in filtering operation, simultaneously, only need to upgrade the coefficient that participates in filtering operation, for example, in the present embodiment, when control module 620 is determined need to be less than the echo canceller on 75 rank time, only need to upgrade 75 coefficients, in this case, 75 filter factors are only upgraded in the 3rd control information that coefficient updating module 640 sends according to control module 620, for example, the 3rd control information can only need to be upgraded the information of 75 filter factors for indication, after coefficient updating module 640 receives the first control information, the filter factor that does not need to upgrade can be set to 0 or do not export these filter factors.
Further, echo canceller 600 also comprises the 3rd delay time register group (Z^-m) 650.The 3rd delay time register group 650 is similar with the 3rd delay time register group 650 of Fig. 3, does not repeat them here.
Fig. 7 be single tap according to another embodiment of the present invention multiplier realize block diagram.
The operation of the multiplier of the single tap in EC is with being shifted.Coef[9:0] be the coefficient of multiplier.Ec_tap[2:0] be the value of delay time register output, i.e. the PAM-5 code signal of 3 bits, value is 0, ± 1, ± 2.PAM-5 numbering is as shown in table 1 with the corresponding relation of line signal level:
PAM-5 coding Line signal level
001 +1
010 +2
111 -1
000 0
110 －2
For example, if ec_tap[2:0]=3 ' b010, be ec_tap[0]=0, ec_tap[1]=1 and ec_tap[2]=0, ' 0 ' branch road for selector 730 and selector 640 is selected, ' 10 ' branch road of ' 0 ' and the selector 710 of selector 720 is selected, the coef[9:0 in ' 10 ' branch road of selector 710] realization that moved to left takes advantage of 2 operation.4 calibrations for fixed-point calculation that move to left below of selector 730 and selector 740.
Fig. 8 is the method for the echo cancelltion of another embodiment according to an embodiment of the invention.
810, the number of the tap that need to use according to echo canceller generates the first control information, the tap of the first control information for selecting this echo canceller to use.
820, the tap of selecting this echo canceller to use according to the first control information, by the echo in selected tap data estimator transmission system, to use the echo in estimated this data transmission system of echo cancelltion going out.
The number of the tap that embodiments of the invention can need to be used according to this echo canceller generates control information, and the tap of selecting this echo canceller to use according to this control information, make echo canceller under short-term pattern, to select less tap to carry out work, thereby reduced the power consumption of system.
In 810, can determine according to the line length of the transmission line of this data transmission system the number of the tap that this echo canceller need to use, and the number of the tap that need to use according to echo canceller generates the first control information, wherein the number of determined tap and the line length of this transmission line are directly proportional.
In 820, the data that the transmitter from this data transmission system can be sent are input to first delay time register M the delay time register being connected in series; The tap of selecting K delay time register in this M being connected in series delay time register to draw according to the first control information is connected to the input of first delay time register in N the delay time register being connected in series; The output of the tap that the output of the tap of respectively K the delay time register of selecting being drawn and this N delay time register are drawn is multiplied by N+1 filter factor and is obtained N+1 product; Cumulative this N+1 product obtains the echo that this estimates, and wherein the number of this definite tap is N+K.
Alternatively, as another embodiment, the method for Fig. 8 also comprises: to decision device, send the above-mentioned echo estimating, so that this decision device is determined error signal according to the above-mentioned echo estimating; According to this error signal, upgrade this N+1 filter factor.
According to embodiments of the invention, in the situation that the number of the tap of this echo canceller is less than or equal to N, by generating the first control information, indicates and select the input of first delay time register in this M delay time register to be connected to the input of first delay time register in this N delay time register.
Alternatively, as another embodiment, in 820, the data that the transmitter from this data transmission system can be sent are input at least one the first delay time register group being connected in series; The data of the tap output that each the first delay time register group in above-mentioned at least one first delay time register group is drawn are multiplied by corresponding filter factor and add up and obtain at least one first accumulation result; According to the first control information, from above-mentioned at least one first accumulation result, select corresponding the first accumulation result; Cumulative selected the first accumulation result obtains the echo that this estimates.
Alternatively, as another embodiment, in 820, the data that the transmitter from this data transmission system can be sent are input to the first delay time register group and at least one the second delay time register group being connected in series; The tap of selecting the output of corresponding the second delay time register group to draw the tap of drawing from the output of above-mentioned at least one the second delay time register group according to the first control information; The data of the tap output that the tap that the output of cumulative described the first delay time register group is drawn and the output of selected the second delay time register group are drawn obtain the echo that this estimates.
Alternatively, as another embodiment, in 820, the data that the transmitter from this data transmission system can be sent are input to the first delay time register group being connected in series; The tap of selecting the output of S delay time register to draw the first delay time register group being connected in series from this according to the first control information; The data of the tap output of respectively output of a selected S delay time register being drawn are multiplied by S filter factor and obtain S product; Cumulative this S product obtains the echo that this estimates.
Alternatively, as another embodiment, the method for Fig. 8 also comprises: to decision device, send the above-mentioned echo estimating, so that this decision device is determined error signal according to the above-mentioned echo estimating; According to the line length of transmission line, generate the 3rd control information; According to the 3rd control information selection, need the number of the filter factor of renewal, and upgrade according to this error signal the filter factor that this need to upgrade.
Alternatively, as another embodiment, the method for Fig. 8 also comprises: according to the line length of this transmission line, generate the second control information, the second control information comprises weighted value; The echo that this is estimated is multiplied by this weighted value, and wherein this weight and this line length are inversely proportional to.
Alternatively, as another embodiment, the method for Fig. 8 also comprises: the input at this echo canceller arranges a plurality of delay time registers, the delay of being introduced to mate the AFE (analog front end) of the transmitter of this data transmission system.
Alternatively, as another embodiment, the method for Fig. 8 also comprises: the training stage before the communicating pair work of this data transmission system is obtained the information of this line length from one of this communicating pair.
According to embodiments of the invention, according to the different line lengths of transmission line, selective filter carries out the exponent number that filtering operation adopts, and closes the part that does not need to participate in filtering operation, thereby reduces power consumption.According to embodiments of the invention, can also make the coefficient update part corresponding with the part of closing filtering operation also not work, further to reduce power consumption.In addition, according to embodiments of the invention by after the weighting of filtering operation result with the filtering results added of equalizer, make the coefficient of echo canceller obtain optimal control in precision and scope.
Those of ordinary skills can recognize, unit and the algorithm steps of each example of describing in conjunction with embodiment disclosed herein, can realize with the combination of electronic hardware or computer software and electronic hardware.These functions are carried out with hardware or software mode actually, depend on application-specific and the design constraint of technical scheme.Professional and technical personnel can specifically should be used for realizing described function with distinct methods to each, but this realization should not thought and exceeds scope of the present invention.
Those skilled in the art can be well understood to, and for convenience and simplicity of description, the specific works process of the system of foregoing description, device and unit, can, with reference to the corresponding process in preceding method embodiment, not repeat them here.
In the several embodiment that provide in the application, should be understood that disclosed system, apparatus and method can realize by another way.For example, device embodiment described above is only schematic, for example, the division of described unit, be only that a kind of logic function is divided, during actual realization, can have other dividing mode, for example a plurality of unit or assembly can in conjunction with or can be integrated into another system, or some features can ignore, or do not carry out.Another point, shown or discussed coupling each other or direct-coupling or communication connection can be by some interfaces, indirect coupling or the communication connection of device or unit can be electrically, machinery or other form.
The described unit as separating component explanation can or can not be also physically to separate, and the parts that show as unit can be or can not be also physical locations, can be positioned at a place, or also can be distributed in a plurality of network element.Can select according to the actual needs some or all of unit wherein to realize the object of the present embodiment scheme.
In addition, each functional unit in each embodiment of the present invention can be integrated in a processing unit, can be also that the independent physics of unit exists, and also can be integrated in a unit two or more unit.
If described function usings that the form of SFU software functional unit realizes and during as production marketing independently or use, can be stored in a computer read/write memory medium.Understanding based on such, the part that technical scheme of the present invention contributes to prior art in essence in other words or the part of this technical scheme can embody with the form of software product, this computer software product is stored in a storage medium, comprise that some instructions are with so that a computer equipment (can be personal computer, server, or the network equipment etc.) carry out all or part of step of method described in each embodiment of the present invention.And aforesaid storage medium comprises: USB flash disk, portable hard drive, read-only memory (ROM, Read-Only Memory), the various media that can be program code stored such as random access memory (RAM, Random Access Memory), magnetic disc or CD.
The above; be only the specific embodiment of the present invention, but protection scope of the present invention is not limited to this, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; can expect easily changing or replacing, within all should being encompassed in protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of claim.
Accompanying drawing explanation
In order to be illustrated more clearly in the technical scheme of the embodiment of the present invention, to the accompanying drawing of required use in the embodiment of the present invention be briefly described below, apparently, below described accompanying drawing be only some embodiments of the present invention, for those of ordinary skills, do not paying under the prerequisite of creative work, can also obtain according to these accompanying drawings other accompanying drawing.
Fig. 1 is the structural schematic diagram of echo canceller according to an embodiment of the invention.
Fig. 2 is the structural schematic diagram of echo canceller according to another embodiment of the present invention.
Fig. 3 is the structural schematic diagram of echo canceller according to another embodiment of the present invention.
Fig. 4 is the structural schematic diagram of echo canceller according to another embodiment of the present invention.
Fig. 5 is the structural schematic diagram of echo canceller according to another embodiment of the present invention.
Fig. 6 is the structural schematic diagram of echo canceller according to another embodiment of the present invention.
Fig. 7 be single tap according to another embodiment of the present invention multiplier realize block diagram.
Fig. 8 is the method for the echo cancelltion of another embodiment according to an embodiment of the 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, obviously, described embodiment is the present invention's part embodiment, rather than whole embodiment.Embodiment based in the present invention, those of ordinary skills, not making the every other embodiment obtaining under creative work prerequisite, belong to the scope of protection of the invention.

Claims (26)

1. an echo canceller, is characterized in that, comprising:
Control module, for determine the number of the tap that described echo canceller need to use according to the line length information of data transmission system transmission line, and generates the first control information according to the number of determined tap;
Filtration module, for the tap of selecting described echo canceller to use according to described the first control information, and by selected tap, estimate the echo in described data transmission system, to use the echo in data transmission system described in the estimated echo cancelltion going out.
2. echo canceller according to claim 1, it is characterized in that, described control module specifically for, according to the line length of the transmission line of described data transmission system, determine the number of the tap that described echo canceller need to use, and according to the number of determined tap, generate described the first control information, the number of the tap that wherein said echo canceller need to use is directly proportional to the line length of described transmission line.
3. echo canceller according to claim 2, is characterized in that, described filtration module comprises:
The first delay time register group, comprise M the delay time register being connected in series, the input of first delay time register in a described M delay time register receives the data of the transmitter transmission of described data transmission system, and the output of a described M delay time register is drawn M tap;
The second delay time register group, comprises N the delay time register being connected in series, and the output of a described N delay time register is drawn N tap;
Selector, the input of described selector is connected to a described M tap, the output of described selector is connected to the input of first delay time register in the second delay time register group, is connected to the input of first delay time register in described the second delay time register group for the tap of selecting K delay time register of a described M tap to draw according to described the first control information;
Multiplier group, comprise N+1 multiplier, the input of a described N+1 multiplier is connected respectively to the tap that the output of N tap that the output of a described N delay time register draws and described K delay time register is drawn, for respectively N+1 data of the described N+1 of an input multiplier being multiplied by N+1 filter factor;
Adder, the echo estimating described in obtaining for the output of a cumulative described N+1 multiplier, the number of wherein said definite tap is N+K.
4. echo canceller according to claim 3, it is characterized in that, described filtration module is sef-adapting filter, the echo estimating described in described filtration module also sends to decision device, so that the echo estimating described in described decision device basis is determined error signal, described echo canceller also comprises:
Coefficient updating module, for upgrading a described N+1 filter factor according to described error signal.
5. echo canceller according to claim 3, it is characterized in that, in the situation that described control module determines that the number of the tap that described echo canceller need to use is less than or equal to N, described control module indicates described selector to select the output of first delay time register in described the first delay time register group to be connected to the input of first delay time register in described the second delay time register group by generating and sending described the first control information.
6. echo canceller according to claim 2, is characterized in that, described filtration module comprises:
At least one first delay time register group, each first delay time register group comprises X the delay time register being connected in series, the output of a described X delay time register is drawn X tap, described at least one first delay time register group is connected in series, and the input of first delay time register in described at least one first delay time register group receives the data of the transmitter transmission of described data transmission system;
At least one multiplier group, each multiplier group comprises X multiplier, be respectively used to X data of the described X of an input multiplier to be multiplied by X filter factor, the input of a described X multiplier is connected respectively to the output of a described X delay time register, and described at least one multiplier group is corresponding with described at least one first delay time register group;
At least one first adder, is respectively used to the output of cumulative described at least one multiplier group, to export at least one first accumulation result;
At least one selector, the input of described at least one selector is connected respectively to the output of described at least one first adder, and described at least one selector is for selecting corresponding the first accumulation result according to described the first control information from described at least one first accumulation result;
Second adder, the echo estimating described in obtaining for the first accumulation result of the output of cumulative described at least one selector.
7. echo canceller according to claim 2, is characterized in that, described filtration module comprises:
The first delay time register group and at least one second delay time register group, each delay time register group comprises X the delay time register being connected in series, the output of a described X delay time register is drawn X tap, described the first delay time register group and described at least one second delay time register group are connected in series, and the input of first delay time register in described the first delay time register group receives the data of the transmitter transmission of described data transmission system;
At least one selector, described at least one selector is connected to the input of described at least one the second delay time register group, the tap output data of described at least one selector for select the output of described at least one the second delay time register group to draw according to described the first control information;
The first multiplier group and at least one second multiplier group, each multiplier group comprises X multiplier, be respectively used to X data of the described X of an input multiplier to be multiplied by X filter factor, the input of X multiplier in described the first multiplier group is connected respectively to the output of X delay time register in described the first delay time register group, the input of X multiplier in each the second multiplier group in described at least one second multiplier group is connected respectively to the output of X delay time register in each the second delay time register group in described at least one second delay time register group,
Adder, the echo estimating described in the data of exporting for the add up output of described the first multiplier group and the output of described at least one the second multiplier group obtain.
8. echo canceller according to claim 2, is characterized in that, described filtration module comprises:
The first delay time register group, comprise Y the delay time register being connected in series, the input of first delay time register in a described Y delay time register receives the data of the transmitter transmission of described data transmission system, and the output of a described Y delay time register is drawn Y tap;
The first group selector, comprises Y selector, and the input of a described Y selector is connected respectively to a described Y tap, and a described Y selector is for selecting S tap of a described Y tap according to described the first control information;
The first multiplier group, comprises Y multiplier, and the input of a described Y multiplier is connected respectively to the output of a described Y selector, is respectively used to Y data of the described Y of an input multiplier to be multiplied by Y filter factor;
Adder, the echo estimating described in obtaining for the output of a cumulative described Y multiplier.
9. according to the echo canceller described in any one in claim 6 to 8, it is characterized in that, described filtration module is sef-adapting filter, the echo estimating described in described filtration module also sends to decision device, so that the echo estimating described in described decision device basis is determined error signal, described control module is also for generating the 3rd control information, described echo canceller also comprises: coefficient updating module, for need the number of the filter factor of renewal according to the 3rd control information selection, and upgrade the described filter factor that needs renewal according to described error signal.
10. according to the echo canceller described in any one in claim 2 to 8, it is characterized in that, described control module is also for generating the second control information according to the line length of described transmission line, and described the second control information comprises weighted value,
Wherein said echo canceller also comprises:
Weighting block, for receiving the second control information, and is multiplied by described weighted value by the described echo estimating, and wherein said weight and described line length are inversely proportional to.
11. according to the echo canceller described in any one in claim 3 to 8, it is characterized in that, also comprises:
The 3rd delay time register group, is connected with the input of described echo canceller, the delay of being introduced to mate the AFE (analog front end) of the transmitter of described data transmission system.
12. according to the echo canceller described in any one in claim 2 to 8, it is characterized in that, described control module is also obtained the information of described line length for the training stage before the communicating pair work in described data transmission system from one of described communicating pair.
13. according to the echo canceller described in any one in claim 2 to 8, it is characterized in that, described transmission line is gigabit Ethernet cable.
14. 1 kinds of data transmission systems, is characterized in that, comprising:
Local transmitter, for sending data to remote receiver;
Local receiver, for receiving data from long-range transmitter;
Blender, is connected between described local transmitter and the transmission line of described data transmission system, and is connected between described local receiver and described transmission line;
According to the echo canceller described in any one in claim 1 to 7, described echo canceller is connected between described local receiver and described blender, the input of described echo canceller receives the data that described local transmitter sends, described in the echo that estimates for the echo of the data eliminating described local receiver and receive.
The method of 15. 1 kinds of echo cancelltions, is characterized in that, comprising:
According to the line length information of transmission line in data transmission system, determine the number of the tap that echo canceller need to use, and according to the number of determined tap, generate the first control information, the tap of described the first control information for selecting described echo canceller to use;
The tap of selecting described echo canceller to use according to described the first control information, estimates the echo in described data transmission system by selected tap, to use the echo in data transmission system described in the estimated echo cancelltion going out.
16. methods according to claim 15, it is characterized in that, the described number of determining the tap that echo canceller need to use according to the line length information of transmission line in data transmission system, and generate the first control information according to the number of determined tap, comprising:
According to the line length of the transmission line of described data transmission system, determine the number of the tap that described echo canceller need to use, and according to the number of determined tap, generate described the first control information, the number of the tap that wherein said echo canceller need to use is directly proportional to the line length of described transmission line.
17. methods according to claim 16, is characterized in that, the described tap of selecting described echo canceller to use according to described the first control information, and the echo by selected tap data estimator transmission system, comprising:
The data that transmitter from described data transmission system is sent are input to first delay time register M the delay time register being connected in series;
The tap that K delay time register in M the delay time register being connected in series described in selecting according to described the first control information drawn is connected to the input of first delay time register in N the delay time register being connected in series;
The output of tap of respectively K the delay time register of selecting being drawn and the output of the tap that a described N delay time register is drawn are multiplied by N+1 filter factor and are obtained N+1 product;
The echo estimating described in a cumulative described N+1 product obtains, the number of wherein said definite tap is N+K.
18. methods according to claim 17, is characterized in that, also comprise:
The echo estimating described in sending to decision device, so that the echo estimating described in described decision device basis is determined error signal;
According to described error signal, upgrade a described N+1 filter factor.
19. methods according to claim 17, it is characterized in that, in the situation that the number of the tap of described echo canceller is less than or equal to N, by generating described the first control information, indicates and select the output of first delay time register in a described M delay time register to be connected to the input of first delay time register in a described N delay time register.
20. methods according to claim 16, is characterized in that, the described tap of selecting described echo canceller to use according to described the first control information, and the echo by selected tap data estimator transmission system, comprising:
The data that transmitter from described data transmission system is sent are input at least one the first delay time register group being connected in series;
The data of the tap output that each the first delay time register group in described at least one first delay time register group is drawn are multiplied by corresponding filter factor and add up and obtain at least one first accumulation result;
According to described the first control information, from described at least one first accumulation result, select corresponding the first accumulation result;
The echo estimating described in cumulative selected the first accumulation result obtains.
21. methods according to claim 16, is characterized in that, the described tap of selecting described echo canceller to use according to described the first control information, and the echo by selected tap data estimator transmission system, comprising:
The data that transmitter from described data transmission system is sent are input to the first delay time register group and at least one the second delay time register group being connected in series;
The tap of selecting the output of corresponding the second delay time register group to draw the tap of drawing from the output of described at least one the second delay time register group according to described the first control information;
The echo that the data of tap that the output of the tap that the output of described the first delay time register group is drawn and selected the second delay time register group is drawn output are multiplied by corresponding filter factor and add up and estimate described in obtaining.
22. methods according to claim 16, is characterized in that, the described tap of selecting described echo canceller to use according to described the first control information, and the echo by selected tap data estimator transmission system, comprising:
The data that transmitter from described data transmission system is sent are input to the first delay time register group being connected in series;
The tap of selecting the output of S delay time register to draw according to described the first control information from described the first delay time register group being connected in series;
The data of the tap output of respectively output of a selected S delay time register being drawn are multiplied by S filter factor and obtain S product;
The echo estimating described in a cumulative described S product obtains.
23. according to claim 16 to the method described in any one in 22, it is characterized in that, also comprises:
The echo estimating described in sending to decision device, so that the echo estimating described in described decision device basis is determined error signal;
According to the line length of described transmission line, generate the 3rd control information;
According to described the 3rd control information selection, need the number of the filter factor of renewal, and upgrade the described filter factor that needs renewal according to described error signal.
24. according to claim 16 to the method described in any one in 22, it is characterized in that, also comprises:
According to the line length of described transmission line, generate the second control information, described the second control information comprises weighted value;
The described echo estimating is multiplied by described weighted value, and wherein said weight and described line length are inversely proportional to.
25. according to claim 17 to the method described in any one in 22, it is characterized in that, also comprises:
Input at described echo canceller arranges a plurality of delay time registers, the delay of being introduced to mate the AFE (analog front end) of the transmitter of described data transmission system.
26. according to claim 16 to the method described in any one in 22, it is characterized in that, also comprises:
Training stage before the communicating pair work of described data transmission system is obtained the information of described line length from one of described communicating pair.
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