CN102780511A - Echo canceller, data transmission system and echo cancellation method - Google Patents
Echo canceller, data transmission system and echo cancellation method Download PDFInfo
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- CN102780511A CN102780511A CN2012102658825A CN201210265882A CN102780511A CN 102780511 A CN102780511 A CN 102780511A CN 2012102658825 A CN2012102658825 A CN 2012102658825A CN 201210265882 A CN201210265882 A CN 201210265882A CN 102780511 A CN102780511 A CN 102780511A
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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
Technical field
The present invention relates to the communications field, especially relate to the unify method of echo cancelltion of a kind of echo canceller, data transmission system.
Background technology
(Gigabit Ethernet Physical Layer GEPHY) is electricity mouthful ethernet physical layer to the gigabit Ethernet physical layer, at five types or surpass five types of unshielded twisted pairs (Unshielded Twisted Pair UTP) goes up the communication of accomplishing both sides.
According to (the Institute of Electrical and Electronics Engineers of IEEE-USA; IEEE) code requirement; The system of 1000Base-T agreement transmits the 4D-PAM5 signal with the 125MBaud modulation rate on 4 pairs of unshielded twisted pairs, reach the full-duplex data transmission of 1Gb/s.The length of cable that 1000Base-T supported is wanted to reach 100 meters, and cable transmission speed is following: (1) 125M symbol (symbol)/second, 2 bit/symbol; (2) to lead be 250Mb/s to the bit on the every pair of line.The GEPHY system uses the 4D-PAM5 signal; Bit error rate (Bit Error Rate, BER) along with signal to noise ratio (Signal Noise Ratio, increase meeting SNR) sharply descends; Thereby receiver needs fully to eliminate to disturb and noise, increases SNR to obtain the less error rate.Simultaneously, at receiver side, must eliminate echo (ECHO) signal as far as possible.
Usually, Adaptive Acoustic Echo Cancellation (ECHO canceller) that can the designs fix exponent number is eliminated echo signal, and under long line situation, echo canceller possibly need more than 150 rank.According to the characteristic of transmission line, the signal delay of 100m line length approximately is 125 symbols; The 10m line approximately is 12.5 symbols.Therefore, for the transmission line of 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, and round numbers is 13 rank; Therefore; Under the short-term pattern,, can increase the power consumption of echo canceller if adopt the echo canceller on 125 rank.
Summary of the invention
The method that embodiments of the invention provide a kind of echo canceller, data transmission system to unify echo cancelltion can reduce the power consumption of echo canceller.
On the one hand, a kind of echo canceller is provided, has comprised: control module, the number of the tap (tap) that is used for using according to this echo canceller needs generates first control information; Filtration module is used for the tap of selecting these echo canceller needs to use according to first control information, and through the echo in the selected tap data estimator transmission system, so that use the echo in estimated this data transmission system of echo cancelltion that goes out.
On the other hand, a kind of data transmission system is provided, has comprised: local transmitter is used for sending data to remote receiver; Local receiver is used 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 being used for that estimates is eliminated the echo of the data of this local receiver reception.
On the other hand, a kind of method of echo cancelltion is provided, has comprised: the number of the tap of using according to the echo canceller needs generates first control information, and first control information is used to the tap of selecting this echo canceller to use; The tap of selecting these echo canceller needs to use according to first control information is through the echo in the selected tap data estimator transmission system, so that use the echo in estimated this data transmission system of echo cancelltion that goes out.
The number of the tap that embodiments of the invention can use according to this echo canceller needs generates control information; And select the tap of this echo canceller needs use according to this control information; Make echo canceller under the short-term pattern, to select less tap to carry out work, thereby reduced the power consumption of system.
Description of drawings
In order to be illustrated more clearly in the technical scheme of the embodiment of the invention; To do to introduce simply to the accompanying drawing of required use in the embodiment of the invention below; Obviously, below described accompanying drawing only be some embodiments of the present invention, for those of ordinary skills; Under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.
Fig. 1 is the structural sketch map of echo canceller according to an embodiment of the invention.
Fig. 2 is the structural sketch map of echo canceller according to another embodiment of the present invention.
Fig. 3 is the structural sketch map of echo canceller according to another embodiment of the present invention.
Fig. 4 is the structural sketch map of echo canceller according to another embodiment of the present invention.
Fig. 5 is the structural sketch map of echo canceller according to another embodiment of the present invention.
Fig. 6 is the structural sketch map of echo canceller according to another embodiment of the present invention.
Fig. 7 is the realization block diagram of the multiplier of single tap according to another embodiment of the present invention.
Fig. 8 is the method for the echo cancelltion of another embodiment according to an embodiment of the invention.
Embodiment
To combine the accompanying drawing in the embodiment of the invention below, the technical scheme in the embodiment of the invention is carried out clear, intactly description, obviously, described embodiment is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills are not making the every other embodiment that is obtained under the creative work prerequisite, all belong to the scope of the present invention's protection.
Term " first " in specification of the present invention and claims and the above-mentioned accompanying drawing, " second ", " the 3rd " " 4th " etc. (if existence) are to be used to distinguish similar object, and needn't be used to describe specific order or precedence.The data that should be appreciated that such use suitably can exchanged under the 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; Be not necessarily limited to those unit so that comprise process, method, system, product or the equipment of a series of 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 sketch map of echo canceller 100 according to an embodiment of the invention.Echo canceller 100 comprises: filtration module 110 and control module 120.
For example; 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 that is provided with in advance or other relevant information are confirmed the number of the tap that echo canceller 100 needs use, and generate first control information according to the number of the tap of confirming.First control information is used to indicate filtration module 110 to select 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 be realized by filter (for example, sef-adapting filter).Data transmission system can be supported the communication under the 1000BASE-T consensus standard, and the transmission line of data transmission system can be the gigabit Ethernet cable.Embodiments of the invention are not limited to this, and for example, data transmission system also can be supported agreements such as 100BASE-TX or 10base-T.
The number of the tap that embodiments of the invention can use according to this echo canceller needs generates control information; And select the tap of this echo canceller needs use according to this control information; Make echo canceller under the short-term pattern, to select less tap to carry out work, thereby reduced the power consumption of system.
Fig. 2 is the structural sketch map of echo canceller 200 according to another embodiment of the present invention.
According to embodiments of the invention; Control module 220 is confirmed the number of the tap that these echo canceller 200 needs use according to the line length of the transmission line of this data transmission system; And the number of the tap of using according to echo canceller 200 needs generates first control information, and wherein the number of determined tap is directly proportional with the line length of this transmission line.
According to embodiments of the invention, control module 220 also is used for training stage before the communicating pair work of this data transmission system and obtains the information of this line length 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 control PHY control process), obtains the information of this line length, and generate control information according to this line length information from one of this communicating pair; This control information is used for selection and needs the filter operating tap, 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 predetermined functional relation with the line length of this transmission line.First control information can be adopted the form of bit.For example, have only at selector under the situation of one tunnel input, first control information is that 1 expression will be imported as output, and first control information is that 0 expression is not exported.Alternatively, first control information can be made up of a plurality of bits, so that can select road input conduct output in the multichannel input.
According to embodiments of the invention; Filtration module 210 comprises: the first delay time register group; Comprise M the delay time register that is 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 that is 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 used for being connected to according to the tap that first control information selects K delay time register of this M tap to draw the input of first delay time register in the second delay time register group; The 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, and N+1 data that are used for will importing respectively this N+1 multiplier multiply by N+1 filter factor; Adder, the output of this N+1 multiplier that is used to add up obtains the echo that this estimates, and the number of the tap that wherein should confirm is N+K.
For example, above-mentioned filter factor can be predefined, also can be real-time update.
For example, the coefficient updating module 240 of echo canceller 200 can the real-time update filter factor.Echo canceller 200 can be implemented as the echo canceller on N+M rank at most, and embodiments of the invention can only upgrade N+1 filter factor under the short-term modular, thereby has reduced power consumption.
According to embodiments of the invention; Confirm that in control module 220 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 through generating and sending first control information under the situation of number smaller or equal to N of the tap that echo canceller 200 need use.
Alternatively; As another embodiment; Filtration module 210 comprises: at least one first delay time register group, each delay time register group comprise X the delay time register that is connected in series, and 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 applied for X data importing this X multiplier and multiply 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 applied for the output of above-mentioned at least one the multiplier group that adds up, 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 used for selecting corresponding first accumulation result according to first control information from said at least one first accumulated value; Second adder, output first accumulation result of above-mentioned at least one selector that is used to add up obtains 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, and each delay time register group comprises X the delay time register that is 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 second delay time register group, and above-mentioned at least one selector is used for the tap of selecting the output of above-mentioned at least one second delay time register group to draw according to first control information; The first multiplier group and at least one second multiplier group; Each multiplier group comprises X multiplier; Be respectively applied for X data importing this X multiplier and multiply 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, and 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; The data of the tap output that adder, the tap that the output of the first delay time register group that is used to add up is drawn and the output of the selected 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 that is 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; 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 used for selecting according to first control information S tap of this Y tap; The first multiplier group comprises Y multiplier, and the input of this T multiplier is connected respectively to the output of this Y selector, and Y data that are respectively applied for this Y of input multiplier multiply by Y filter factor; Adder, the output of this T multiplier that is used to add up obtains the echo that this estimates.
For example, above-mentioned filter factor can be predefined, also can be real-time update.
Alternatively, as another embodiment, filtration module 210 is a sef-adapting filter, and filtration module 210 also sends the above-mentioned echo that estimates to decision device, so that decision device is confirmed error signal according to the above-mentioned echo that estimates.Echo cancellation module 200 comprises: coefficient updating module 240 is used for generating the 3rd control information according to the line length of transmission line; According to the number of the 3rd control information selection needs updated filter coefficients, and according to this needs updated filter coefficients of error signal renewal.
For example, in the above-described embodiments, if need to confirm the Echo Canceller on 50 rank; Then coefficient updating module 240 is only upgraded 50 filter factors according to the 3rd control information; Promptly can under the short-term modular, can only upgrade less filter factor, thereby reduce power consumption.
This control module 220 also is used for generating second control information according to the line length of this transmission line; Second control information comprises weighted value; Wherein this echo canceller 200 also comprises: weighting block 230; Be used to receive second control information, and the echo that this estimates multiply by this weighted value, wherein this weight and this line length are inversely proportional to.
Embodiments of the invention can be directed against different line lengths, and the proportion when adjustment echo is eliminated computing makes that the coefficient precision of echo canceller 200 and scope are optimum.
The echo canceller 200 of Fig. 2 also comprises: the 3rd delay time register group 250 is connected the delay of being introduced with the AFE(analog front end) of the transmitter that matees said 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 be provided with the delay time register group at the inlet of echo canceller 200; Through selecting the number of delay cell; The delay of transmission symbol (TX Symbol) in the adjustment echo canceller 200 is so that accurately the delay that front end is introduced is sent in the coupling simulation.
According to embodiments of the invention a kind of data transmission system is provided, has comprised: local transmitter is used for sending data to remote receiver; Local receiver is used for receiving data from long-range transmitter; Blender is connected between the transmission line of this this locality transmitter and 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 being used for that estimates is eliminated the echo of the data of this local receiver reception.
For example, echo canceller can be an independent device, also can be installed on the local receiver.
Fig. 3 is the structural sketch map 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 used for generating first control information according to the number of the tap of echo canceller 300 needs use.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 the physical layer control procedure; Two communication terminals when training through consultation mode obtain line length information, for example, first communication terminal sends signal and gives the second communication terminal; Response is returned to first communication terminal after receiving this signal in the second communication terminal, and first communication terminal can be known the moment of sending this signal and receive the time difference between moment of 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 preestablish line length information according to first known communication terminal and the distance between the second communication terminal.
After having confirmed line length information, control module 320 can be confirmed the number of the tap that echo canceller 300 needs use according to line length information, and wherein the number of determined tap is directly proportional with the line length of transmission line.For example, according to the characteristic of transmission line, the signal delay of 100m line length approximately is 125 symbols, and the 10m line approximately is 12.5 symbols.Therefore, when line length was 100m, the exponent number of echo canceller 300 (corresponding to the exponent number of sef-adapting filter) needed 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.
After the number of the exponent number of confirming echo canceller 300 needs according to line length information or tap; Control module 320 can generate first control information according to the number of determined tap, and first control information is used to control the tap number that filtration module 310 uses as required and selects corresponding tap to carry out echo cancelltion.First control information can be mask, for example ... 00001000000000 ..., wherein in the present embodiment, totally 129, promptly 0 ~ 128.This mask is used to make filtration module 310 to select corresponding tap to be used 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 confirmed is 30+K, and promptly 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.Be not limited to this according to embodiments of the invention; 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, and the second delay time register group can comprise 50 delay time registers, or the like.
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 are used to accomplish echo cancelltion by the output valve of the output valve of K delay time register D and the second delay time register group 312.For example; When training; Control module 320 is learnt the echo canceller on needs 50 rank according to line length; Then utilize first control information to select the 20th rank in the first delay time register group 311 to export input, through the 30 rank output of the second delay time register group 312, realize the filtering operation on 50 rank jointly again as the second delay time register group.
Especially; The number of confirming the tap that echo cancellers 300 need to use in control module 320 smaller or equal to 30 (for example; The line length of transmission line is smaller or equal to 24m) situation under; Control module 320 is sent first control information to selector, and the tap that the 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 0th of mask the value 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), the data symbol that is respectively applied for the above-mentioned 30+1 of an input multiplier multiply by 30+1 filter factor.
Adder 315, the echo signal that the echo canceller 300 of above-mentioned 30+1 the multiplier output that is used to add up estimates, and the echo signal that estimates outputed to weighting block 330.
Control module 320 also is used for generating second control information according to the line length of transmission line, and second control information comprises weighted value.Weighting block 330 is used to receive second control information that comprises weighted value that control module 320 is sent; Receive the echo signal that estimates of adder 315 outputs; And the echo signal that estimates multiply 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.Second control information (ratio_ctrl) is used to regulate the proportion of filter factor, and according to the difference of line length, echo signal can use different weight coefficients when eliminating, and obtains maximum dynamic range to guarantee filter coefficient, thereby improves the precision of 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 bigger; Through regulating the ratio of this echo signal, the coefficient value of the filter in the time of can letting different line length is in a consistent relatively scope; For example, in the PHY control stage, be long line if confirm as transmission line, then the weighting control 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) addition obtains signal ffe_ec_dat; (Decision Feed Back Equalizer, output signal (dfe_data_out) addition DFE) obtains signal r for signal ffe_ec_dat and feedback equalizer
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, repeat no more at this.
Coefficient updating module 340 can adopt lowest mean square, and (Least mean square, LMS) coefficient update algorithm for example, are C based on the coefficient update formula of LMS
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 the coefficient update step-length; Symbol manipulation is got in the sgn representative; Select through mask (mask) signal after the tap of echo canceller, have only the second delay time register group to participate in filtering operation, simultaneously, only needing to upgrade the coefficient of participating in filtering operation (is coefficient C
i, C
I+1..., C
I+N), for example, in the present embodiment, even under long ray mode, also only need to upgrade 31 coefficients.
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; Promptly can adjust the delay of the data symbol (Symbol) of echo canceller 300 receptions, send the delay that front end is introduced with accurate coupling simulation through the number m that selects delay time register in the 3rd delay time register group.The 3rd delay time register group 350 can be connected the input (or inlet) of echo canceller 300, promptly 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) (for example as the input data symbol of filtration module 310; Ec_data_in), and the data symbol that will pass through after the delay send to filtration module 310.
Fig. 4 is the structural sketch map 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.
After the number of the tap of confirming echo canceller 400 needs according to line length information or exponent number; Control module 420 can generate first control information according to the number of determined tap, and first control information is used to control the tap number that filtration module 410 uses as required and selects corresponding tap to carry out echo cancelltion.Different with the control module of Fig. 3 is that the control module 420 of Fig. 4 drives different selectors through first control information, carries out echo cancelltion to select different taps.Referring to Fig. 4, control module 420 control selectors 417 are selected different taps with selector 419.
Filtration module 410 comprises that the first delay time register group 411, second group postpone to deposit 412, the 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 receive the driving of 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.Confirm to send first control information and give selector 417 and selector 419 need be less than the echo canceller on 75 rank the time when control module 420, make selector 417 conductings respectively and selector 419 is turn-offed, like this, participate in 75 taps of having only of filtering operation.Confirm to send first control information and give selector 417 and selector 419 need be greater than the echo canceller on 75 rank the time when control module 420, make selector 417 and selector 419 equal conductings, the tap of participating in computing like this be 150.
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, repeats no more at this.
Should be understood that at least one delay time register group of to connect 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 the 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 by control module 420 controls, and give weighting block 430 by the echo signal that this another adder output estimates.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 sketch map 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.
After the number of the tap of confirming echo canceller 500 needs according to line length information or exponent number; Control module 520 can generate first control information according to the number of determined tap, and first control information is used to control the tap number that filtration module 510 uses as required and selects corresponding tap to carry out echo cancelltion.Different with the control module of Fig. 3 320 is that the control module 520 of Fig. 5 is carried out echo cancelltion through the first control information driving selection device to select different taps.Referring to Fig. 5, control module 520 control selectors 516 are selected different taps.
Filtration module 510 comprises that the first delay time register group 511, second group postpone to deposit 512, the 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 receives the driving of 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.Confirm to send first control information and give selector 516 need be less than the echo canceller on 75 rank the time when control module 520, selector 516 is turn-offed, like this, participate in 75 taps of having only of filtering operation.Confirm to send first control information and give selector 516 need be greater than the echo canceller on 75 rank the time when control module 520, make selector 516 conductings, the tap of participating in computing like this be 150.
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, repeats no more at this.
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; Can connect selector between two adjacent delay time register groups; These selectors receive the control of control modules 520, participate in filtering operation to select not tap on the same group.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 sketch map 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.
After the number of the tap of confirming echo canceller 600 needs according to line length information or exponent number; Control module 620 can generate first control information according to the number of determined tap, and first control information is used to control the tap number that filtration module 610 uses as required and selects corresponding tap to carry out echo cancelltion.Different with the control module of Fig. 3 320 is that the control module 620 of Fig. 6 drives different selectors through first control information, carries out echo cancelltion to select different taps.Referring to Fig. 6, control module 620 control selector groups 612 are selected different taps.
For example, suppose that echo canceller 600 has 150 delay time registers.Confirm to send first control information to selector group 613 need be less than the echo canceller on 75 rank the time when control module 620, make preceding 75 selector conductings, back 75 selectors turn-off, and like this, participate in 75 taps of having only of filtering operation.
Coefficient updating module 640 can adopt lowest mean square, and (Least mean square, LMS) coefficient update algorithm for example, are C based on the coefficient update formula of LMS
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 the coefficient update step-length; Symbol manipulation is got in the sgn representative; After the tap through first control information control selector group, 612 selection echo cancellers, can have only part or all of tap to participate in filtering operation, simultaneously; Only need to upgrade the coefficient of participating in filtering operation, for example, in the present embodiment; When control module 620 is confirmed need be less than the echo canceller on 75 rank the 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 is sent according to control module 620; For example; The 3rd control information can only need to upgrade the information of 75 filter factors for indication, and coefficient updating module 640 receives after first control information, can perhaps not export these filter factors with not needing updated filter coefficients to be changed to 0.
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, repeats no more at this.
Fig. 7 is the realization block diagram of the multiplier of single tap according to another embodiment of the present invention.
The displacement of manipulating of the multiplier of the single tap among the EC is accomplished.Coef [9:0] is the coefficient of multiplier.Ec_tap [2:0] is the value of delay time register output, i.e. the PAM-5 code signal of 3 bits, and value is 0, ± 1, ± 2.The PAM-5 numbering is as shown in table 1 with the corresponding relation of line signal level:
| The PAM-5 coding | The line signal level |
| 001 | +1 |
| 010 | +2 |
| 111 | -1 |
| 000 | 0 |
| 110 | －2 |
For example; If ec_tap [2:0]=3 ' is b010; Be ec_tap [0]=0, ec_tap [1]=1 and ec_tap [2]=0, selected for ' 0 ' branch road of selector then 730 and selector 640; ' 10 ' branch road of ' 0 ' and the selector 710 of selector 720 is selected, and 2 operation is taken advantage of in the realization that moved to left of the coef [9:0] in ' 10 ' branch road of selector 710.4 calibrations that are used for fixed-point calculation that move to left of selector 730 and selector 740 back.
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 of using according to the echo canceller needs generates first control information, and first control information is used to the tap of selecting this echo canceller to use.
820, the tap of selecting these echo canceller needs to use according to first control information is through the echo in the selected tap data estimator transmission system, so that use the echo in estimated this data transmission system of echo cancelltion that goes out.
The number of the tap that embodiments of the invention can use according to this echo canceller needs generates control information; And select the tap of this echo canceller needs use according to this control information; Make echo canceller under the short-term pattern, to select less tap to carry out work, thereby reduced the power consumption of system.
In 810; Can confirm the number of the tap that these echo canceller needs use according to the line length of the transmission line of this data transmission system; And the number of the tap of using according to the echo canceller needs generates first control information, and wherein the number of determined tap is directly proportional with the line length of this transmission line.
In 820, the data that can the transmitter from this data transmission system be sent are input to first delay time register M the delay time register that is connected in series; The tap of selecting K delay time register in this M that is connected in series delay time register to draw according to first control information is connected to the input of first delay time register in N the delay time register that is connected in series; The output of the tap that the output of the tap that K delay time register will selecting respectively drawn and this N delay time register are drawn multiply by N+1 filter factor and is obtained N+1 product; This N+1 product that adds up obtains the echo that this estimates, and the number of the tap that wherein should confirm is N+K.
Alternatively, as another embodiment, the method for Fig. 8 also comprises: send the above-mentioned echo that estimates to decision device, so that this decision device is confirmed error signal according to the above-mentioned echo that estimates; Upgrade this N+1 filter factor according to this error signal.
According to embodiments of the invention; Under the situation of number smaller or equal to N of the tap of this echo canceller, indicate the input of selecting 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 through generating first control information.
Alternatively, as another embodiment, in 820, the data that can the transmitter from this data transmission system be sent are input at least one the first delay time register group that is 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 multiply by corresponding filter factor and add up and obtain at least one first accumulation result; Select corresponding first accumulation result according to first control information from above-mentioned at least one first accumulation result; Selected first accumulation result that adds up obtains the echo that this estimates.
Alternatively, as another embodiment, in 820, the data that can the transmitter from this data transmission system be sent are input to the first delay time register group and at least one second delay time register group that is connected in series; The tap of from the tap that the output of above-mentioned at least one second delay time register group is drawn, selecting the output of the corresponding second delay time register group to draw according to first control information; The data of the tap output that the tap that the output of the said first delay time register group that adds up is drawn and the output of the selected second delay time register group are drawn obtain the echo that this estimates.
Alternatively, as another embodiment, in 820, the data that can the transmitter from this data transmission system be sent are input to the first delay time register group that is connected in series; The tap of from the first delay time register group that this is connected in series, selecting the output of S delay time register to draw according to first control information; The data that the tap of respectively output of a selected S delay time register being drawn is exported multiply by S filter factor and obtain S product; This S product that adds up obtains the echo that this estimates.
Alternatively, as another embodiment, the method for Fig. 8 also comprises: send the above-mentioned echo that estimates to decision device, so that this decision device is confirmed error signal according to the above-mentioned echo that estimates; Line length according to transmission line generates the 3rd control information; According to the number of the 3rd control information selection needs updated filter coefficients, and according to this this needs updated filter coefficients of error signal renewal.
Alternatively, as another embodiment, the method for Fig. 8 also comprises: the line length according to this transmission line generates second control information, and second control information comprises weighted value; This echo that estimates multiply 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 is provided with a plurality of delay time registers, the delay of being introduced with the AFE(analog front end) of the transmitter that matees 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 the different line lengths of embodiments of the invention according to transmission line, selective filter carries out the exponent number that filtering operation adopted, and closes the part that need not participate in filtering operation, thereby reduces power consumption.The corresponding coefficient update part of part that can also make and close the filtering operation according to embodiments of the invention is not worked yet, with further reduction power consumption.In addition, according to embodiments of the invention with filtering operation weighting as a result after with the filtered addition of equalizer, make the coefficient of echo canceller on precision and scope, obtain optimal control.
Those of ordinary skills can recognize, the unit and the algorithm steps of each example of describing in conjunction with embodiment disclosed herein can be realized with the combination of electronic hardware or computer software and electronic hardware.These functions still are that software mode is carried out with hardware actually, depend on the application-specific and the design constraint of technical scheme.The professional and technical personnel can use distinct methods to realize described function to each certain applications, but this realization should not thought and exceeds scope of the present invention.
The those skilled in the art can be well understood to, for the convenience described with succinct, the concrete course of work of the system of foregoing description, device and unit can repeat no more at this with reference to the corresponding process among the preceding method embodiment.
In several embodiment that the application provided, should be understood that the system that is disclosed, apparatus and method can realize through other mode.For example, device embodiment described above only is schematically, for example; The division of said unit; Only be that a kind of logic function is divided, during actual the realization other dividing mode can be arranged, for example a plurality of unit or assembly can combine or can be integrated into another system; Or some characteristics can ignore, or do not carry out.Another point, the coupling each other that shows or discuss or directly coupling or communication to connect can be through some interfaces, the INDIRECT COUPLING of device or unit or communication connect, and can be electrically, machinery or other form.
Said unit as separating component explanation can or can not be physically to separate also, and the parts that show as the unit can be or can not be physical locations also, promptly can be positioned at a place, perhaps also can be distributed on a plurality of NEs.Can realize the purpose of present embodiment scheme according to the needs selection some or all of unit wherein of reality.
In addition, each functional unit in each embodiment of the present invention can be integrated in the processing unit, also can be that the independent physics in each unit exists, and also can be integrated in the unit two or more unit.
If said function realizes with the form of SFU software functional unit and during as independently production marketing or use, can be stored in the computer read/write memory medium.Based on such understanding; 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 be come out with the embodied of software product; This computer software product is stored in the storage medium; Comprise some instructions with so that computer equipment (can be personal computer, server, the perhaps network equipment etc.) carry out all or part of step of the said method of each embodiment of the present invention.And aforesaid storage medium comprises: various media that can be program code stored such as USB flash disk, portable hard drive, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disc or CD.
The above; Be merely embodiment of the present invention, but protection scope of the present invention is not limited thereto, any technical staff who is familiar with the present technique field is in the technical scope that the present invention discloses; Can expect easily changing or replacement, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of claim.
Claims (26)
1. an echo canceller is characterized in that, comprising:
Control module, the number of the tap that is used for using according to said echo canceller needs generates first control information;
Filtration module; Be used for selecting the tap of said echo canceller needs use according to said first control information; And through the echo in the selected tap data estimator transmission system, so that use the echo in the estimated said data transmission system of echo cancelltion that goes out.
2. echo canceller according to claim 1; It is characterized in that; Said control module specifically is used for; Confirm the number of the tap that said echo canceller needs use according to the line length of the transmission line of said data transmission system, and generate said first control information according to the number of determined tap, the number of the tap that wherein said echo canceller need use is directly proportional with the line length of said transmission line.
3. echo canceller according to claim 2 is characterized in that, said filtration module comprises:
The first delay time register group; Comprise M the delay time register that is connected in series; The input of first delay time register in the said M delay time register receives the data of the transmitter transmission of said data transmission system, and the output of a said M delay time register is drawn M tap;
The second delay time register group comprises N the delay time register that is connected in series, and the output of a said N delay time register is drawn N tap;
Selector; The input of said selector is connected to a said M tap; The output of said selector is connected to the input of first delay time register in the second delay time register group, is used for being connected to according to the tap that said first control information selects K delay time register of a said M tap to draw the input of first delay time register in the said second delay time register group;
The multiplier group; Comprise N+1 multiplier; The input of a said N+1 multiplier is connected respectively to the tap that the output of N tap that the output of a said N delay time register draws and said K delay time register is drawn, and N+1 data that are used for will importing respectively a said N+1 multiplier multiply by N+1 filter factor;
Adder, the output of the said N+1 multiplier that is used to add up obtains the said echo that estimates, and the number of wherein said definite tap is N+K.
4. echo canceller according to claim 3; It is characterized in that; Said filtration module is a sef-adapting filter; Said filtration module also sends the said echo that estimates to decision device, so that said decision device is confirmed error signal according to the said echo that estimates, said echo canceller also comprises:
Coefficient updating module is used for upgrading a said N+1 filter factor according to said error signal.
5. according to claim 3 or 4 described echo cancellers; It is characterized in that; Confirm in said control module under the situation of number smaller or equal to N of the tap that said echo canceller need use that said control module indicates said selector to select the input of first delay time register in the said first delay time register group to be connected to the input of first delay time register in the said second delay time register group through generating and sending said first control information.
6. echo canceller according to claim 2 is characterized in that, said filtration module comprises:
At least one first delay time register group; Each first delay time register group comprises X the delay time register that is connected in series; The output of a said X delay time register is drawn X tap; Said at least one first delay time register group is connected in series, and the input of first delay time register in said at least one first delay time register group receives the data of the transmitter transmission of said data transmission system;
At least one multiplier group; Each multiplier group comprises X multiplier; Be respectively applied for X data importing a said X multiplier and multiply by X filter factor; The input of a said X multiplier is connected respectively to the output of a said X delay time register, and said at least one multiplier group is corresponding with said at least one first delay time register group;
At least one first adder is respectively applied for the output of said at least one the multiplier group that adds up, to export at least one first accumulation result;
At least one selector; The input of said at least one selector is connected respectively to the output of said at least one first adder, and said at least one selector is used for selecting corresponding first accumulation result according to said first control information from said at least one first accumulated value;
Second adder, first accumulation result of the output of said at least one selector that is used to add up obtains the said echo that estimates.
7. echo canceller according to claim 2 is characterized in that, said 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 that is connected in series; The output of a said X delay time register is drawn X tap; The said first delay time register group and said at least one second delay time register group are connected in series, and the input of first delay time register in the said first delay time register group receives the data of the transmitter transmission of said data transmission system;
At least one selector; Said at least one selector is connected to the input of said at least one second delay time register group, and said at least one selector is used for the tap dateout of selecting the output of said at least one second delay time register group to draw according to said first control information;
The first multiplier group and at least one second multiplier group; Each multiplier group comprises X multiplier; Be respectively applied for X data importing a said X multiplier and multiply by X filter factor; The input of X multiplier in the said first multiplier group is connected respectively to the output of X delay time register in the said first delay time register group, and the input of X multiplier in each the second multiplier group in said 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 said at least one second delay time register group;
The data of the tap output that adder, the tap that the output of the said first delay time register group that is used to add up is drawn and the output of the selected second delay time register group are drawn obtain the said echo that estimates.
8. echo canceller according to claim 2 is characterized in that, said filtration module comprises:
The first delay time register group; Comprise Y the delay time register that is connected in series; The input of first delay time register in the said Y delay time register receives the data of the transmitter transmission of said data transmission system, and the output of a said Y delay time register is drawn Y tap;
First group selector comprises T selector, and the input of a said Y selector is connected respectively to a said Y tap, and a said Y selector is used for selecting according to said first control information S tap of a said Y tap;
The first multiplier group comprises Y multiplier, and the input of a said T multiplier is connected respectively to the output of a said Y selector, and Y data that are respectively applied for the said Y of an input multiplier multiply by Y filter factor;
Adder, the output of the said T multiplier that is used to add up obtains the said echo that estimates.
9. according to each the described echo canceller in the claim 6 to 8; It is characterized in that; Said filtration module is a sef-adapting filter, and said filtration module also sends the said echo that estimates to decision device, so that said decision device is confirmed error signal according to the said echo that estimates; Said control module also is used to generate the 3rd control information; Said echo canceller also comprises: coefficient updating module is used for the number according to the 3rd control information selection needs updated filter coefficients, and upgrades said needs updated filter coefficients according to said error signal.
10. according to each the described echo canceller in the claim 2 to 9, it is characterized in that said control module also is used for generating second control information according to the line length of said transmission line, said second control information comprises weighted value,
Wherein said echo canceller also comprises:
Weighting block is used to receive second control information, and the said echo that estimates multiply by said weighted value, and wherein said weight and said line length are inversely proportional to.
11. each the described echo canceller according in the claim 3 to 10 is characterized in that, also comprises:
The 3rd delay time register group is connected with the input of said echo canceller, the delay of being introduced with the AFE(analog front end) of the transmitter that matees said data transmission system.
12. each the described echo canceller according in the claim 2 to 11 is characterized in that, said control module also is used for training stage before the communicating pair work of said data transmission system and obtains the information of said line length from one of said communicating pair.
13. each the described echo canceller according in the claim 2 to 12 is characterized in that said transmission line is the gigabit Ethernet cable.
14. a data transmission system is characterized in that, comprising:
Local transmitter is used for sending data to remote receiver;
Local receiver is used for receiving data from long-range transmitter;
Blender is connected between the transmission line of said local transmitter and said data transmission system, and is connected between said local receiver and the said transmission line;
According to each the described echo canceller in the claim 1 to 7; Said echo canceller is connected between said local receiver and the said blender; The input of said echo canceller receives the data that said local transmitter sends, and said echo being used for that estimates eliminated the echo of the data of said local receiver reception.
15. the method for an echo cancelltion is characterized in that, comprising:
The number of the tap of using according to the echo canceller needs generates first control information, and said first control information is used to the tap of selecting said echo canceller to use;
The tap of selecting said echo canceller needs to use according to said first control information is through the echo in the selected tap data estimator transmission system, so that use the echo in the estimated said data transmission system of echo cancelltion that goes out.
16. method according to claim 15 is characterized in that, the number of the said tap of using according to said echo canceller needs generates first control information, comprising:
Confirm the number of the tap that said echo canceller needs use according to the line length of the transmission line of said data transmission system; And the number according to determined tap generates said first control information, and the number of the tap that wherein said echo canceller need use is directly proportional with the line length of said transmission line.
17. method according to claim 16 is characterized in that, the said tap of selecting said echo canceller needs to use according to said first control information, and the echo through in the selected tap data estimator transmission system comprises:
The data that to send from the transmitter of said data transmission system are input to first delay time register M the delay time register that is connected in series;
The tap of selecting K delay time register in the said M that the is connected in series delay time register to draw according to said first control information is connected to the input of first delay time register in N the delay time register that is connected in series;
The output of the tap that the output of the tap that K delay time register will selecting respectively drawn and a said N delay time register are drawn multiply by N+1 filter factor and is obtained N+1 product;
The said N+1 product that adds up obtains the said echo that estimates, and the number of wherein said definite tap is N+K.
18. method according to claim 17 is characterized in that, also comprises:
Send the said echo that estimates to decision device, so that said decision device is confirmed error signal according to the said echo that estimates;
Upgrade a said N+1 filter factor according to said error signal.
19. according to claim 17 or 18 described methods; It is characterized in that; Under the situation of number smaller or equal to N of the tap of said echo canceller, indicate the input of selecting first delay time register in the said M delay time register to be connected to the input of first delay time register in the said N delay time register through generating said first control information.
20. method according to claim 16 is characterized in that, the said tap of selecting said echo canceller needs to use according to said first control information, and the echo through in the selected tap data estimator transmission system comprises:
The data that to send from the transmitter of said data transmission system are input at least one the first delay time register group that is connected in series;
The data of the tap output that each the first delay time register group in said at least one first delay time register group is drawn multiply by corresponding filter factor and add up and obtain at least one first accumulation result;
Select corresponding first accumulation result according to said first control information from said at least one first accumulation result;
Selected first accumulation result that adds up obtains the said echo that estimates.
21. method according to claim 16 is characterized in that, the said tap of selecting said echo canceller needs to use according to said first control information, and the echo through in the selected tap data estimator transmission system comprises:
The data that to send from the transmitter of said data transmission system are input to the first delay time register group and at least one second delay time register group that is connected in series;
The tap of from the tap that the output of said at least one second delay time register group is drawn, selecting the output of the corresponding second delay time register group to draw according to said first control information;
The data of the tap output that the tap that the output of the said first delay time register group that adds up is drawn and the output of the selected second delay time register group are drawn obtain the said echo that estimates.
22. method according to claim 16 is characterized in that, the said tap of selecting said echo canceller needs to use according to said first control information, and the echo through in the selected tap data estimator transmission system comprises:
The data that to send from the transmitter of said data transmission system are input to the first delay time register group that is connected in series;
The tap of from the said first delay time register group that is connected in series, selecting the output of S delay time register to draw according to said first control information;
The data that the tap of respectively output of a selected S delay time register being drawn is exported multiply by S filter factor and obtain S product;
The said S product that adds up obtains the said echo that estimates.
23. each the described method according in the claim 20 to 22 is characterized in that, also comprises:
Send the said echo that estimates to decision device, so that said decision device is confirmed error signal according to the said echo that estimates;
Line length according to said transmission line generates the 3rd control information;
According to the number of said the 3rd control information selection needs updated filter coefficients, and upgrade said needs updated filter coefficients according to said error signal.
24. each the described method according in the claim 16 to 23 is characterized in that, also comprises:
Line length according to said transmission line generates second control information, and said second control information comprises weighted value;
The said echo that estimates multiply by said weighted value, and wherein said weight and said line length are inversely proportional to.
25. each the described method according in the claim 17 to 24 is characterized in that, also comprises:
Input at said echo canceller is provided with a plurality of delay time registers, the delay of being introduced with the AFE(analog front end) of the transmitter that matees said data transmission system.
26. each the described method according in the claim 16 to 25 is characterized in that, also comprises:
Training stage before the communicating pair work of said data transmission system is obtained the information of said line length from one of said communicating pair.
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