CN102158617B - Communicating method and device for digital subscriber technique - Google Patents
Communicating method and device for digital subscriber technique Download PDFInfo
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Abstract
The invention discloses a communicating method for digital subscriber technique, which comprises the following steps: acquiring a communication property parameter, and communicating according to a preset communication rule by a first transmitter-receiver device and a second transmitter-receiver device, when the communication property parameter reaches or exceeds a preset value, wherein the preset communication rule is respectively arranged in the first and second transmitter-receiver devices. The invention also discloses a transmitter-receiver device for communicating in the digital subscriber technique. According to the method, a bit table and a gain table are predetermined and then the bit table and the gain table are respectively stored in the first and second transmitter-receiver devices. When high broadband noise (such as crosstalk) exists, the predetermined bit table and gain table can be quickly switched by utilizing a simple message or query-answer system. The bit table and the gain table are not required for exchanging, so the technical scheme of the invention has the advantages of high switching speed and high reliability. Besides, by the using of the method and device provided by the invention, the use ratio of high frequency spectrum can be increased.
Description
Technical field
The present invention relates to a kind of communication technology, relate in particular to a kind of method and apparatus that in digital user line technology, communicates.
Background technology
ADSL (ADSL (Asymmetric Digital Subscriber Line)) technology is through for many years development, developed into the VDSL2 (second high-speed digital user wire) of present ADSL2 (second generation ADSL), ADSL2+ (ADSL2 of downlink bandwidth expansion) and renewal from the ADSL of the first generation, the frequency band of its use is increasing gradually, and corresponding bandwidth is also increasing gradually.The following frequency spectrum of the descending use of ADSL and ADSL2 1.1MHz can provide the downstream rate of maximum 8Mbps, ADSL2+ expands to 2.2MHz with downlink bandwidth, the downstream rate of maximum 24Mbps can be provided, and VDSL2 even use can provide the access rate of the symmetrical 100Mbit/s of the highest up-downgoing up to the frequency spectrum of 30MHz.Above-mentioned various digital user line technology is referred to as xDSL.
Because the transmission medium of xDSL is unshielded twisted pair, has electromagnetic coupled between the different twisted-pair feeders, therefore, the signal that transmits on a pair of twisted-pair feeder can be transferred on the other twisted-pair feeder by the approach of electromagnetic coupled, and formation is crosstalked.In order to reduce this crosstalking, twisted-pair feeder has adopted different laies, and xDSL employing differential signal transmission itself and reception, utilizes as far as possible the symmetry of twisted-pair feeder to offset common mode interference signal, the symmetry of twisted-pair feeder or limited in the reality, crosstalking still exists.In addition, the interference signal in the external environment also can be coupled on the twisted-pair feeder, converts difference mode signal because the symmetry of twisted-pair feeder is limited to and forms interference.
Line between crosstalk can cause very large impact to business.For example, its adjacent circuit does not have business when line is trained 1, under given Signal to Noise Ratio Margin, can obtain higher activation rate, and after this adjacent circuit also begins training, the amplitude of the noise increase and decrease that the signal that these circuits send causes the crosstalk signal that produces on 1 online might reach tens dB, the line of original setting this moment can not guarantee that to 1 Signal to Noise Ratio Margin (being generally 6dB) circuit is with the original error rate and speed operation, this moment is then error rate increase gently, heavy then the retraining that goes offline causes service disconnection.This problem is even more serious in the situation of VDSL2, because the frequency of VDSL2 is high, circuit is short, and far-end cross talk increases along with the increase of frequency, decays along with the increase of distance, thereby cross talk effects is larger.ADSL2+ has defined the Fast Training mode, although have quick retraining can so that connect the fastest can be extensive in 3 seconds kinds
Multiple, but the impact for business can't be avoided fully, and some professional meeting is because need to reconnect such as the problem that goes offline, such as IP phone etc., so keep the communication connection quality good (as, do not go offline) experience for the quality of business and user very important meaning arranged.
In the prior art, have following three kinds of schemes can tackle this because the silent status that contiguous circuit never uses (under silent status, do not have signal on the circuit) change crosstalking of normal use generation over to, the below is described respectively above-mentioned three kinds of technical schemes.
Scheme one, by improving line to 1 target signal to noise ratio tolerance limit, reserve more Signal to Noise Ratio Margin during online to 1 training, need only the increase amplitude when crosstalking when increasing suddenly like this and do not meet or exceed the target signal to noise ratio tolerance limit, communication still can keep target error rate, and enough surpluses are arranged and is unlikely to retraining.The benefit of this technical scheme is simple and practical, weak point is to improve Signal to Noise Ratio Margin will cause line to 1 obtained rate reduction, and because crosstalk noise generally is not smooth, the noise power spectral density that is to say different frequent points is different, and Signal to Noise Ratio Margin is a smooth value, it reserves essentially identical value as tolerance limit with the signal to noise ratio of all subchannels, consider in fact crosstalk only more serious in some frequency range, therefore in the very little frequency range of which cross talk effects, too high signal to noise ratio is brought the waste of transmission capacity.
Scheme two, use seamless rate adaptation (Seamless Rate Adaptation, SRA), when circuit causes signal to noise ratio to reduce because of crosstalking, SRA guarantees Signal to Noise Ratio Margin by reducing the bit number of modulating on the affected subcarrier, thereby the error rate is not higher than desired value, and this scheme can be adjusted bit distribution according to the distribution of noise automatically, thereby has avoided the problem of scheme one.But SRA need to and upgrade the table of bits of subcarrier and gain table (during multi-carrier communication according to the change calculations of signal to noise ratio, Bit Allocation in Discrete table on each subcarrier and gain adjustment form, ADSL or VDSL standard referring to ITU-T), data volume is larger, be subjected to the impact of the transmittability of expense passage, its response speed is slow, and crosstalking of adjacent lines is to increase suddenly in the moment that enters training, therefore, very possible SRA also has little time to finish and adjusts R-T unit with regard to the retraining because make mistakes continuously.Further, SRA need to transmit a large amount of data (bit and gain table) between receiving system and dispensing device, and the signal to noise ratio of channel has descended at this moment, and the process of SRA update bit and gain table itself might be made mistakes and failure.
Scheme three G.993.2 in standard (the being again VDSL2) standard, has been introduced the concept of virtual noise (Virtual Noise, VN) at ITU-T, and this is the noise that a kind of as required shaping obtains.Fig. 1 shows the relation between a kind of virtual noise and the actual noise, and dotted line is the virtual noise change curve, and solid line is the noise change curve.If with this virtual noise calculation signal to noise ratio, and the bit that calculates each subcarrier loads, just obtain a kind of take the line speed of VN as the basis, by suitable VN is set, so that VN is not less than the crosstalk noise of maximum possible in the basic master-strapped unit of cable (such as in the VDSL situation, base unit for 25 pairs, what produce when VN being set being not less than 24 pairs of lines and activating simultaneously crosstalks), even these lines can not cause its retraining to training after reaching showtime (this is a special term in the standard, is called again synchronous regime) to 1 online yet like this.And owing to adopt the noise of shaping, only reserve enough surpluses at the subchannel of needs, just can avoid simply arranging the waste that smooth target signal to noise ratio tolerance limit is brought.But the problem of this scheme is that this still is a conservative scheme, in order to guarantee safety, need to design VN with the crosstalk noise of maximum possible, such as 1% worst case, but crosstalking in fact a lot of situations do not have so not poor or just this worst case occurs in a short period of time, and moves the waste that has in fact still caused channel capacity with this conservative scheme all the time.
Summary of the invention
The purpose of this invention is to provide a kind of method and system that in digital user line technology, communicates, can be according to the noise situation of change dynamic adaptation transmission rate of circuit, improve antimierophonic performance, in order to avoid the variety of issue (as going offline) that causes because of significantly improving of circuit noise, especially be applicable to noise situation about significantly improving occurs suddenly at short notice.And when circuit noise reduces, can dynamically heighten line speed, thereby improved transmission capacity.
The invention discloses a kind of method that in digital user line technology, communicates, comprising:
A, acquisition communication performance parameter;
B, when the communication performance parameter meets or exceeds predetermined value, the first R-T unit and the second R-T unit adopt predetermined rule of communication to communicate.
Described predetermined rule of communication can set in advance respectively in the first R-T unit and the second R-T unit, perhaps obtains according to the scheduled communication rule computational methods that are separately positioned in the first R-T unit and the second R-T unit when communication.
Described steps A specifically comprises: the monitoring module monitors communication performance parameter of the first R-T unit and the second R-T unit, described communication performance parameter comprise signal to noise ratio, Signal to Noise Ratio Margin and error rate three one of them or combination in any.
Described step B specifically comprises:
When signal to noise ratio, Signal to Noise Ratio Margin, the error rate of the monitoring of the first R-T unit and/or the second R-T unit when wherein the combination of arbitrary parameter meets or exceeds predetermined value, the first R-T unit and/or the second R-T unit send handover request message to the second R-T unit and/or the first R-T unit, make the first R-T unit and the second R-T unit adopt predetermined rule of communication to communicate.
Described handover request message adopts the message of embedded expense passage.
Described handover request message adopts type of message 2, type of message 3 and self-defining message three one of them or the combination in any of the embedded expense passage of VDSL2 standard definition.
Described step B also comprises: receive the handover request message of the first R-T unit and/or the second R-T unit when the second R-T unit and/or the first R-T unit, the second R-T unit and/or the first R-T unit send response message by embedded expense passage to the first R-T unit and/or the second R-T unit.
The content of described response message comprises to be agreed to switch and the refusal switching.
When the content of response message was switched for refusal, described response message also comprised the cause information that refusal switches.
Described step B also comprises: adopt synchronizing symbol to realize the synchronous switching of the first R-T unit and/or the second R-T unit.
With the entrained information of synchronizing symbol from full 0 to complete 1 saltus step or opposite saltus step realize switching synchronously.
Described steps A specifically comprises: A1, obtain the communication performance parameter by challenge-response mechanism.
Described steps A 1 specifically comprises:
A11, the first R-T unit/second R-T unit send apply for information by the time frame period to the second R-T unit/first R-T unit, and the second R-T unit/first R-T unit returns response message by the time frame period to the first R-T unit/second R-T unit;
A12, the first R-T unit/second R-T unit determine the communication performance parameter according to replying of receiving/apply for information situation.
Described steps A 12 specifically comprises:
A121, when the second R-T unit/first R-T unit is not received the correct apply for information that sends of the first R-T unit/second R-T unit in predetermined time interval, then with the current location 1 of the circulating register of the second R-T unit/first R-T unit, otherwise, with the current location 0 of the circulating register of the second R-T unit/first R-T unit;
A122, when the first R-T unit/second R-T unit is not received the response message that the second R-T unit/the first R-T unit correctly returns in predetermined time interval, then with the current location 1 of the circulating register of the first R-T unit/second R-T unit, otherwise, with the current location 0 of the circulating register of the first R-T unit/second R-T unit;
A123, the circulation of the circulating register of the first R-T unit/second R-T unit is moved forward one;
1 number in A124, the first R-T unit/the second R-T unit statistics circulating register, until 1 number reaches till the switching threshold in the circulating register, otherwise, return steps A 11.
Described step B specifically comprises:
When the first R-T unit and/or the second R-T unit obtain the communication performance parameter and meet or exceed predetermined value, adopt the parameter in the predetermined table of bits to communicate at predetermined instant the first R-T unit and the second R-T unit.
Described predetermined instant is the tenth symbol of next synchronization frame.
Described predetermined rule of communication comprises: predetermined table of bits and/or gain table.
Described predetermined table of bits can be table of bits or the experience table of bits that adopts virtual noise to calculate.
Described method also comprises: adopting before predetermined table of bits and/or gain table communicate, described the first R-T unit and the second R-T unit adopt table of bits and/or the gain table of actual noise calculation to communicate.
After adopting predetermined table of bits and/or gain table to communicate, described method also comprises: adopt the table of bits of seamless rate adaptation method adjustment to communicate.
The invention also discloses a kind of R-T unit in digital user line technology, comprising:
Receiver module is used for receiving signal from subscribers feeder;
Monitoring modular, the signal that is used for receiving according to described receiver module obtains the communication performance parameter;
Processing module is for the switching of the rule of communication of being scheduled to according to monitoring modular line quality parameter;
Sending module is used for to the subscribers feeder transmitted signal.
Described processing module specifically comprises:
Memory cell is used for storing predetermined rule of communication;
Judging unit is used for judging whether the communication performance parameter meets or exceeds predetermined value, if start switch unit;
Switch unit is used for switching to predetermined rule of communication.
Described predetermined rule of communication comprises: predetermined table of bits and/or gain table.
Described communication performance parameter comprises signal to noise ratio, Signal to Noise Ratio Margin and/or the error rate.
Described predetermined table of bits can be table of bits or the experience table of bits that adopts virtual noise to calculate.
Described device also comprises: the seamless rate adaptation device is used for according to calculating table of bits and gain table according to current actual noise.
Described receiver module also is used for receiving table of bits and the gain table that the opposite end sends, and described sending module also is used for to opposite end transmission table of bits and gain table.
The invention also discloses a kind of receive-transmit system in digital user line technology, described receive-transmit system comprises the first R-T unit and the second R-T unit by subscribers feeder communication,
The first R-T unit obtains the communication performance parameter, and when the communication performance parameter met or exceeded predetermined value, the first R-T unit and the second R-T unit adopted predetermined rule of communication to communicate;
The second R-T unit obtains the communication performance parameter, and when the communication performance parameter met or exceeded predetermined value, the first R-T unit and the second R-T unit adopted the parameter in the predetermined table of bits to communicate.
Described the first R-T unit and the second R-T unit comprise respectively:
Receiver module is used for the signal that receives from subscribers feeder;
Monitoring modular, the signal that is used for receiving according to described receiver module obtains the communication performance parameter;
Processing module, for the switching of the rule of communication of being scheduled to according to monitoring modular line quality parameter, described predetermined rule of communication is preserved local;
Sending module is used for to the subscribers feeder transmitted signal.
Described the first R-T unit and the second R-T unit also comprise respectively: the seamless rate adaptation device is used for calculating table of bits and gain table according to actual noise.
Described receiver module also is used for receiving table of bits and the gain table that the opposite end sends, and described sending module also is used for to opposite end transmission table of bits and gain table.
Described predetermined rule of communication sets in advance respectively in the first R-T unit and the second R-T unit, perhaps obtains according to the scheduled communication rule computational methods that are separately positioned in the first R-T unit and the second R-T unit when communication.
According to the present invention, by pre-determined table of bits, gain table, and table of bits, the gain table of determining be kept at respectively in the first R-T unit and the second R-T unit, or determine in advance the computation rule that an energy is understood and used by the first R-T unit and the second R-T unit.When very large broadband noise (as crosstalking) occurring, utilize simple message or challenge-response mechanism, the quick switching of realization from the table of bits of current use, gain table to pre-determined table of bits, gain table, or use the table of bits of current use, gain table to calculate table of bits, the gain table that makes new advances and switch to fast new table of bits, gain table by pre-determined rule.Owing to need to not exchange table of bits, gain table between the first R-T unit and the second R-T unit, therefore, it is fast that technical scheme of the present invention has switch speed, the advantage that reliability is high.And when above-mentioned broadband noise reduces (as, the crosstalk sources user closes modem), can also obtain SNRM with current channel calculation, by SRA speed is heightened, thereby improved the availability of frequency spectrum.
Description of drawings
Fig. 1 shows the example that concerns between virtual noise and the actual noise;
Fig. 2 shows the schematic diagram of receiving system of the present invention;
Fig. 3 shows the graph of a relation between circuit noise, Signal to Noise Ratio Margin and the line speed;
Fig. 4 shows the schematic diagram of apply for information and response message;
Fig. 5 shows the challenge-response process between the first R-T unit and the second R-T unit;
Fig. 6 is the schematic diagram when mistake appears in the challenge-response process between the first R-T unit and the second R-T unit;
Fig. 7 shows the challenge-response process of utilizing between the first R-T unit and the second R-T unit and carries out the schematic diagram that table of bits is switched.
Embodiment
Understand and realization the present invention the existing embodiments of the invention of describing by reference to the accompanying drawings for the ease of persons skilled in the art.
As shown in Figure 2, the invention discloses a kind of receive-transmit system in digital user line technology, described system comprises: the first R-T unit, be used for obtaining the communication performance parameter, when the communication performance parameter met or exceeded predetermined value, the first R-T unit and the second R-T unit adopted predetermined rule of communication to communicate, and described predetermined rule of communication is arranged in the first R-T unit, otherwise, adopt the table of bits of calculating according to actual noise, the parameter in the gain table to communicate; The second R-T unit, be used for obtaining the communication performance parameter, when the communication performance parameter meets or exceeds predetermined value, the first R-T unit and the second R-T unit adopt the parameter in the predetermined table of bits to communicate, described predetermined rule of communication is arranged in the second R-T unit, otherwise, adopt the table of bits of calculating according to actual noise, the parameter in the gain table to communicate.
The constitute and function of the first R-T unit and the second R-T unit can be just the same.One of them R-T unit can be arranged in local side apparatus, and another R-T unit is arranged in ustomer premises access equipment.Described R-T unit comprises: receiver module, for the signal and the message that receive the other side's R-T unit; Monitoring modular is used for obtaining the communication performance parameter from receiver module, and described communication performance parameter comprises signal to noise ratio, Signal to Noise Ratio Margin, the error rate; Processing module, message is switched in switching and generation for the rule of communication of being scheduled to according to monitoring modular communication performance parameter, and according to the switching of switching the rule of communication that message is scheduled to, described predetermined rule of communication comprises table of bits and/or gain table; Sending module is used for to the described switching message of the other side's R-T unit transmitted signal and processing module generation.
Described processing module specifically comprises: memory cell, for table of bits, the gain table of storing the predetermined table of bits of described two parts of rule of communications, gain table and calculating according to actual noise, and some configuration parameters, such as triggering table of bits, the gain table (bi﹠amp with the error rate or Signal to Noise Ratio Margin definition; The information such as switching threshold gi); Judging unit is used for judging whether the communication performance parameter meets or exceeds predetermined value, if, then produce and switch message, and send to the opposite end by sending module, wait for the synchronizing signal of opposite end, when the synchronizing signal that obtains in the given time the opposite end, start switch unit; Switch unit, the table of bits, the gain table that are used for carrying out to predetermined are switched.
Described R-T unit also comprises: the seamless rate adaptation device, be used for calculating table of bits and gain table according to actual noise, when reducing noise with its as new rule of communication with raising speed.Described receiver module also be used for to receive table of bits and the gain table that the opposite end sends, and described sending module also is used for to sending table of bits and gain table.
The invention also discloses the method that communicates in digital user line technology, described method comprises: obtain the communication performance parameter; Judge whether the communication performance parameter meets or exceeds predetermined value, if, R-T unit by message informing the other side, make the two ends R-T unit adopt predetermined table of bits, the parameter in the gain table to communicate, otherwise, adopt the table of bits of calculating according to actual noise, the parameter in the gain table to communicate.
In order to obtain the communication performance parameter, monitoring modular is constantly monitored the signal that receiver module receives, and from the signal that receives, obtain the communication performance parameters such as signal to noise ratio, Signal to Noise Ratio Margin, the error rate, when wherein one or more meet or exceed predetermined value with these parameters of box lunch, by message informing the other side's R-T unit, make the two ends R-T unit adopt predetermined table of bits, the parameter in the gain table to communicate.
After obtaining the communication performance parameter, judge whether the communication performance parameter meets or exceeds predetermined value, if, R-T unit by message informing the other side, make the R-T unit at two ends adopt predetermined table of bits, the parameter in the gain table to communicate, otherwise, adopt the table of bits of calculating according to actual noise, the parameter in the gain table to communicate.
In order to judge whether the communication performance parameter meets or exceeds predetermined value, before training, can in the first R-T unit (supposing that the first R-T unit is in the local side apparatus), set in advance virtual noise or experience table of bits calculating parameter, and Signal to Noise Ratio Margin and or the threshold value of the error rate; Described experience table of bits calculating parameter for the upper bit number that calculates according to actual noise of each tone (frequency sub-band) should reduce so that the bit number of Signal to Noise Ratio Margin to be provided, then with the virtual noise or the experience table of bits calculating parameter that arrange, Signal to Noise Ratio Margin and or the threshold value of the error rate be stored in the memory module of the first R-T unit, so that in training process by information interaction with virtual noise or experience table of bits calculating parameter, and Signal to Noise Ratio Margin and or the threshold value of the error rate be dealt into the second R-T unit (supposing that the second R-T unit is in the subscriber terminal equipment), the second R-T unit is virtual noise or experience table of bits calculating parameter, and Signal to Noise Ratio Margin and or the threshold value of the error rate be saved in the memory module.The processing module of the second R-T unit is according to its signal of receiving when training, respectively with default virtual noise or experience table of bits calculating parameter and signal to noise ratio table corresponding to actual noise calculating two covers, table of bits and gain table: SNRvi, Bvi and Gvi, SNRri, Bri and Gri, and with SNRvi, Bvi and Gvi, SNRri, Bri and Gri are stored in the local memory module and by information interaction and are sent to the first R-T unit, in order to preserve in the memory module of the first R-T unit, then the first R-T unit and the second R-T unit are with the SNRri of actual noise calculating, Bri is connected with Gri connecting.
The following describes and judge whether the communication performance parameter meets or exceeds the process of predetermined value.The first R-T unit and/or the second R-T unit are compared the predetermined threshold value of storing in the signal to noise ratio, Signal to Noise Ratio Margin, the error rate of monitoring and its memory module.Take the monitoring Signal to Noise Ratio Margin as example, when finding that a plurality of subcarriers (distribute according to the power of crosstalking, in most cases be a lot of continuous subcarriers), when being lower than default threshold value such as the Signal to Noise Ratio Margin of 10 continuous subcarriers, show exist because adjacent threads to the situation of the unexpected increase that causes in training crosstalking, this moment, R-T unit produced a handover request message, and sent handover request message to the other side's R-T unit.After the other side's R-T unit receives handover request message, switch to table of bits, the gain table calculated by virtual noise or experience table of bits calculating parameter, then return an acknowledge message and synchronization message (also can only return synchronization message), after R-T unit receives the confirmation message and synchronization message, switch to table of bits, the gain table calculated by virtual noise.Like this, the first R-T unit and the second R-T unit can use table of bits, the gain table calculated by virtual noise to communicate.
Described predetermined table of bits, gain table can be for obtaining or the experience table of bits according to default virtual noise.
Can crosstalk for circuit the is the worst noise of situation of described virtual noise.Like this, in training, the first R-T unit and the second R-T unit are except the actual noise according to u interface (interface of xDSL transceiver and outer twisted pairs) obtains signal to noise ratio table SNRri, table of bits Bri and gain table Gri, the data (SNRvi, Bvi and Gvi) of also calculating another part correspondence according to default virtual noise or experience table of bits calculating parameter, described signal to noise ratio table SNRri, table of bits Bri and gain table Gri represent that respectively the signal to noise ratio of each subcarrier, bit number and the relative gain of carrying adjust coefficient.Described (SNRvi, Bvi and Gvi) is kept at respectively in the memory module of the first R-T unit and the second R-T unit.When the R-T unit detection line owing to adjacent threads causes signal to noise ratio snr i and/or Signal to Noise Ratio Margin SNRMi and/or error rate BER (Bit Error Rate) when meeting or exceeding predefined value to crosstalking of producing of training, R-T unit can send handover request message to the opposite end R-T unit, so that the opposite end R-T unit switches to the Bvi and the Gvi that calculate with virtual noise or experience table of bits calculating parameter of preservation, and realize synchronous switching between the first R-T unit and the second R-T unit by switching synchronizing signal.
Described experience table of bits can rule of thumb obtain, such as distribute the bit gain table bri﹠amp based on actual noise that is obtaining according to training result according to the experience of crosstalking; Cut corresponding bit number (increase of the Signal to Noise Ratio Margin that the bit number that deducts brings should be greater than or equal to the drop-out value of the Signal to Noise Ratio Margin that causes of crosstalking) on the basis of gri, so just do not need to design virtual noise and passed to the opposite end, thereby further simplify the operation.
Because bit loading and the gain adjustment form calculated according to virtual noise are very conservative schemes, therefore although Signal to Noise Ratio Margin and the error rate meet the demands (normally meeting or exceeding requirement), but speed can be low than the value that actual noise obtains, this moment can be by the means of SRA, progressively heighten line speed according to the SNRri of reality.So just obtaining a fast reducing speed increases suddenly to adapt to noise, advance the speed at a slow speed to adapt to the dynamic rate shaping process that noise reduces, because all calculated in advance is complete for the line parameter circuit value in this fast handover procedures, and on the first R-T unit and the second R-T unit, preservation is arranged, therefore when needing to switch as long as simple message and synchronization message just can realize, more originally SRA or BS are faster, also more reliable, because SRA or BS need to transmit update bit table and gain table, and because channel is relatively poor, table of bits and the gain table that might cause because of the error code in the transmission course transmitting are made mistakes and failure, the solution of the present invention does not then have this problem, and when the circuit crosstalk noise reduces, signal to noise ratio increases, and the error rate descends, and can transmit the mass data that SRA needs.
When entering showtime, signal to noise ratio table SNRri, the table of bits Bri that can calculate according to actual noise and gain table Gri are as transformation parameter, in order to obtain larger transmission rate.
Fig. 3 shows the graph of a relation between circuit noise, Signal to Noise Ratio Margin and the line speed.As shown in Figure 3, axis of abscissas is the time, shows relation between circuit noise, Signal to Noise Ratio Margin and the line speed at ordinate.At time a place, because adjacent threads so that circuit noise significantly raises, thereby so that SNRM sharply descends, like this, according to the present invention, switches to predetermined bit gain table, changing down to beginning training; At time b-c place, after adjacent threads finished training, adjacent threads was controlled the stage to ingoing power, crosstalks slightly to descend, be that circuit noise descends to some extent, thereby so that SNRM increase to some extent, like this, according to the present invention, can adjust speed by SRA, so that line speed increases; At time d-e place, when adjacent threads the user is closed modem, crosstalk and decline to a great extent, namely circuit noise declines to a great extent, thereby so that SNRM increases, like this, according to the present invention, can adjust speed by SRA, and line speed is improved.
In order to realize the present invention, also need definition to switch message, defined eoc (embedded overhead channel, the embedded expense passage) message of OLR order in the standard (ITU-T G.993.2) of VDSL2, order type field is (00000001)
2, subscript 2 expression binary systems, other Field Definition is as shown in the table.
Table 11-7/G.993.2 one Reason codes for OLR responses
As can be seen from the above table, Type 1 has been used, according to the present invention, can directly use Type 2 or Type3, and field length is decided to be 2byte, and the 2nd byte content is respectively (as shown in Table): 05
16, 06
16, subscript 16 expressions 16 systems.Also can decide in addition message a: Type 4, its length is 2byte, and the 2nd byte content is 07
16, so just can not affect current standard definition.Similarly, it is as shown in the table relatively to switch the form of response message of message.
Therefore, if directly adopt existing type2 or type3, then corresponding message field is made amendment, agree that length of handover is 2 bytes, wherein, second byte is 72
16Perhaps 73
16(corresponding to type of message); The length that refusal switches is 3byte, and wherein, the second byte is 82
16Perhaps 83
16(corresponding to type of message), the 3rd byte is the reason (optional, if not, then length is two bytes) of refusal.If the type 4 of new definition, then type 4 is answered in definition, agrees that the message-length that switches is two bytes, and wherein, second byte is 73
16, refuse information length 3byte, wherein, the second byte is 83
16, the 3rd byte is the reason (optional, if not, then length is two bytes) of refusal.G.993.2 synchronizing signal then adopts the signal of definition, namely adopts the switching between the full 0 and complete 1 of synchronizing symbol to represent synchronizing signal.
Said method has more message content, can more convenient both sides link up.In order to accelerate switch speed, can send one and not need the handover request message Type2 or Type3 or the Type4 that confirm, then R-T unit is carried out change action after receiving this message, and informs synchronously switching of receiving terminal realization with synchronizing symbol, if refusal does not then send synchronization message.Like this, avoid transmission and the resolving of message content, accelerated switch speed, reduced error probability.
According to above-described embodiment, in training, calculate in advance two cover parameters, table of bits, the gain table of one cover for obtaining according to current channel parameter (such as interchannel noise), another set of for according to virtual noise or or experience table of bits calculating parameter conservative table of bits, the gain table that obtain, and this two covers parameter preserved in the first R-T unit and the second R-T unit simultaneously.The R-T unit use was table of bits, the gain table that obtains according to current channel parameter when training was finished, and be called current table of bits, gain table, and this part bit gain table can dynamically be adjusted along with channel variation (such as bit swapping).When very large broadband noise (such as crosstalking) occurring, utilize simple message, the quick switching of realization from current table of bits, gain table to table of bits corresponding to virtual noise, gain table, owing to do not need to exchange table of bits, gain table, only need to exchange simple message, therefore with respect to bit exchange, SRA, it is fast that the scheme of present embodiment has switch speed, the advantage that reliability is high.And when above-mentioned broadband noise reduces (user closes modem such as crosstalk sources), can also calculate SNRM with current channel parameter, and by SRA speed is heightened, thus the optimization of the realization availability of frequency spectrum.
In addition, because the solution of the present invention switch speed is fast, thereby can responds the characteristics of this unexpected increase of crosstalking and avoid going offline, SRA then may be because of response speed and makeing mistakes of exchange parameter process and failure causes retraining and interrupting service.
In order to obtain the communication performance parameter, also can adopt following challenge-response mode.Particularly, judge the quality of circuit according to the challenge-response situation.The below describes the method that obtains line quality by the challenge-response mode in detail.
As shown in Figure 4, at first construct apply for information and response message, Fig. 4 (a) shows apply for information, and Fig. 4 (b) shows response message.Suppose that the first R-T unit sends apply for information to the second R-T unit.
When counting is for X (span of X is 0-255) in the inquiry message that the second R-T unit receives, make an immediate response, and the counting byte of the response message that responds should be X+1.If overflow when occuring, the value of counting byte be made as zero.When the first R-T unit receives response message, and during the content legality of counting byte, send inquiry message after crossing certain time interval (T), and the legal counting byte content of counting byte content for receiving from the second R-T unit.The like.Fig. 5 shows the challenge-response process between the first R-T unit and the second R-T unit.
As shown in Figure 6, when the second R-T unit did not correctly receive the apply for information that the first R-T unit sends, the second R-T unit was not replied.When the first R-T unit does not correctly receive the response message that receiving terminal sends, identical apply for information once on official hour point continues to repeat to send.
In order to record the challenge-response situation, can be provided with register at the first R-T unit and the second R-T unit, each records respectively the accepting state of a continuous n message register.For convenience of description, the register in the first R-T unit, the first R-T unit replaces with TM and RM respectively.After the initialization or after the switching of bit list item, the initial value of TM and RM should be zero entirely.
For the first R-T unit, in current time frame, if the first R-T unit does not receive legal response message in the official hour interval, write ' 1 ' in the present bit of TM, otherwise write ' 0 '; Then, the first R-T unit receives the response message in next time frame, will be defined as present bit at the next bit of TM, if do not receive legal response message in the official hour interval, writes ' 1 ' in the present bit of TM, otherwise writes ' 0 '.
For the second R-T unit, in current time frame, if when the second R-T unit does not receive legal apply for information in the official hour interval, write ' 1 ' in the present bit of RM, otherwise write ' 0 '; Then, the second R-T unit receives the apply for information in next time frame, will be defined as present bit at the next bit of RM, if do not receive legal apply for information in the official hour interval, writes ' 1 ' in the present bit of RM, otherwise writes ' 0 '.
At the first R-T unit, when the position that predetermined number (being switching threshold) is arranged in the TM register is ' 1 ', just determine to switch in the moment of the first R-T unit and the second R-T unit agreement, for example do table of bits, gain table switching at the tenth symbol of next synchronization frame.In order to guarantee synchronous switching, after determining to switch, send all the time invalid data, so that the second R-T unit reaches switching condition as early as possible, and then do table of bits, gain table switching at the tenth symbol of next synchronization frame.Like this, between the first R-T unit and the second R-T unit, do not need send to switch message, just can realize switching synchronously table of bits, the variety of issue that causes with the unexpected increase of the noise (as crosstalking) of tackling the circuit of dashing forward, as go offline.To the second R-T unit, also adopt same mechanism, in order to carry out the switching of table of bits.
The position that Fig. 7 shows TM and RM is 5, the challenge-response situation during switching threshold value 3.As shown in Figure 7, solid line represents that this transmission of messages is correct, and the dotted line line represents this transmission of messages mistake.In the 1st time frame, the first R-T unit is 001 apply for information to the second R-T unit transmission counting byte, after the second R-T unit receives apply for information, returning the counting byte to the first R-T unit is 002 response message, at this moment the every of the TM of the first R-T unit and the second R-T unit and RM does not change, and namely is 0.In the 2nd time frame, TM and RM be one of loopy moving forward respectively, the first R-T unit is 002 apply for information to the second R-T unit transmission counting byte, the second R-T unit is not received apply for information, still returning the counting byte to the first R-T unit is 002 response message, and at this moment the present bit of the TM of the first R-T unit and the second R-T unit and RM (last position as shown in the figure) all is set as 1.In the 3rd time frame, TM and RM be one of loopy moving forward respectively, the first R-T unit is 002 apply for information to the second R-T unit transmission counting byte, after the second R-T unit receives apply for information, receive correct, the present bit of the RM of the second R-T unit remains 0, then returning the counting byte to the first R-T unit is 003 response message, because the first R-T unit is not received response message in the official hour interval, at this moment the present bit of the TM of the first R-T unit is set to 1.Like this, the rest may be inferred, until during the 7th time frame, 1 number (switching threshold) reaches 3 among the TM of the first R-T unit, since the 8th time frame, it is the apply for information of wrong content that the first R-T unit sends the counting byte to the second R-T unit, in order to make the number of 1 among the RM of the second R-T unit arrive as early as possible switching threshold, switch in order to when the tenth symbol of next synchronization frame, carry out table of bits, like this, do not need again pass-along message between the first R-T unit and the second R-T unit, just can realize the synchronous switching of table of bits, therefore, it is fast that the scheme of present embodiment has switch speed, the advantage that reliability is high.And when above-mentioned broadband noise reduces (user closes modem such as crosstalk sources), calculate SNRM with current channel parameter, by SRA speed is heightened, thereby the optimization of the realization availability of frequency spectrum has improved transmission speed.
Should be noted that, when carrying out the switching of table of bits, can carry out the switching of gain table, also can not carry out the switching of gain table.
In sum, by pre-determined table of bits, gain table, and table of bits, the gain table of determining be kept at respectively in the first R-T unit and the second R-T unit.When very large broadband noise (such as crosstalking) occurring, utilize simple message or challenge-response mechanism, realize the quick switching from current table of bits, gain table to pre-determined table of bits, gain table.Owing to do not need to exchange table of bits, gain table, therefore, it is fast that technical scheme of the present invention has switch speed, the advantage that reliability is high.And when above-mentioned broadband noise reduces (user closes modem such as crosstalk sources), can also obtain SNRM with current channel calculation, and by SRA speed is heightened, thus the optimization of the realization availability of frequency spectrum.
Although described the present invention by embodiment, those of ordinary skills know, without departing from the spirit and substance in the present invention, just can make the present invention that many distortion and variation are arranged, and scope of the present invention is limited to the appended claims.
Claims (8)
1. a method that communicates in digital user line technology is characterized in that, comprising:
Obtain the communication performance parameter;
When the communication performance parameter met or exceeded predetermined value, the first R-T unit and the second R-T unit adopted predetermined rule of communication to communicate;
Wherein, described the first R-T unit sends to described the second R-T unit by information interaction with the table of bits calculating parameter;
When the communication performance parameter met or exceeded predetermined value, described the first R-T unit sent handover request message to described the second R-T unit;
After receiving described handover request message, described the second R-T unit switches to table of bits and/or the gain table by virtual noise or rule of thumb table of bits calculating parameter calculating, and informs synchronously switching of described the first R-T unit realization by synchronizing symbol.
2. method according to claim 1 is characterized in that, described predetermined rule of communication comprises table of bits and/or gain table.
3. method according to claim 1 is characterized in that, described communication performance parameter comprises signal to noise ratio, Signal to Noise Ratio Margin and error rate three one of them or combination in any.
4. method according to claim 1 is characterized in that, the standard I TU-T of described handover request message employing VDSL2 is the embedded expense passage EOC message of middle definition G.993.2.
5. method according to claim 1 is characterized in that, also comprises: according to the communication performance parameter of current reality, described the first R-T unit and the second R-T unit are heightened line speed by the seamless rate adaptation method.
6. digital subscriber line system, comprise the first R-T unit and the second R-T unit that communicate by Digital Subscriber Line, it is characterized in that, described the first R-T unit obtains the communication performance parameter, when described communication performance parameter met or exceeded predetermined value, described the first R-T unit and described the second R-T unit adopted predetermined rule of communication to communicate;
Wherein, described the first R-T unit is used for by information interaction the table of bits calculating parameter being sent to described the second R-T unit, and sends handover request message to described the second R-T unit when described communication performance parameter meets or exceeds predetermined value;
Described the second R-T unit is used for after receiving described handover request message, switch to table of bits and/or gain table by virtual noise or rule of thumb table of bits calculating parameter calculating, and inform synchronously switching of described the first R-T unit realization by synchronizing symbol.
7. digital subscriber line system as claimed in claim 6 is characterized in that, described predetermined rule of communication comprises table of bits and/or gain table.
8. digital subscriber line system according to claim 7 is characterized in that, described the first R-T unit and the second R-T unit also are used for the communication performance parameter according to current reality, progressively heighten line speed by the seamless rate adaptation method.
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