CN108234053A - A kind of method of estimation of the maximum time interval error of T1 data-signals - Google Patents

Abstract

The present invention provides the timing information in a kind of related pseudo-wire stream of packets by processing to estimate the system and method for T1 timing errors and clock recovery error, and wherein T1 is extracted from pseudo-wire stream of packets.Timing error is proposed in the form of MTIE measured values, is alerted and available for being sent out in Network Operation Centre available for accurately sending out error condition alarm in the case where the T1 signals for restoring or extracting cannot meet MTIE or clock accuracy error.There may be excessive packet jitter, drift or the situations of phase transformation, wherein pseudo-wire stream to be transmitted by Packet Data Network for detecting in Packet Data Network for this alarm, and on the other hand, these errors are used to control the recovery of T1 clock informations.

Description

A kind of method of estimation of the maximum time interval error of T1 data-signals

Technical field

The present invention relates to the estimations and monitoring of timing errors in packet data networks.It is more particularly related to a kind of be used to estimate It counts timing/phase drift and is using the Information recovering T1/DS1 clocks extracted from timing pseudo-wire or packet data streams System and method.

Background technology

Those skilled in the art will appreciate：Time division multiplexing (TDM, TimeDivision currently used for wireless network Multiplexing) timing recovery techniques there is also some problems, TDM technologies use what is restored from pseudo-wire packet data streams TDM clocks.Many networks depend on restored TDM signals timing accuracy, it is therefore desirable to a kind of method come judge timing be It is no correct.

In history, cellular network using T1/DS1 signals carries out data transmission that the logical of Timed Recovery can be traced with network with other Believe equipment, what is used is all wired T1/DS1 circuits.These wire circuits or with the direct carried of T1 circuit forms, Huo Zhecong It is extracted in wired T3/DS3 circuits or SDH/SONET light paths, these are all TDM circuits.For example, T1 or DS1 circuits can be by T3 or DS3 circuits generate, and can carry 28 T1.DS3 circuits can be transmitted with STS-1 circuit forms in optical-fiber network, wherein, one A OC-3 can carry 3 STS-1 circuits.Identical STS-1 circuits can in the TDM light paths of higher rate carried, example Such as OC-12, OC-48, OC-192 or OC-768.In addition, other technologies, such as asynchronous transfer mode (ATM, Asynchronous Transfer Mode) it can be used for carrying T1 circuits.In destination, timing is obtained using back mapping Restore signal.Rigid line TDM circuit namely non-cellular systems, in American National Standard telecommunications industry association-network and user installation Interface-DS1 electrical interfaces (American National Standard Institute forTelecommunications- Network and Customer Installation Interfaces-DS1ElectricalInterface)ANSI In T1.403-1999 fully definition and specification.T1 TSC Telecommunication Standardization Committees (StandardsCommittee T1Telecommunications) it is responsible for this document, being defined in 6.3 chapters and sections of the document influences receiver recovery data bit With the key point of shake, drift and the phase transformation of tracking T1 signal recovered clock abilities.Crucial specification is as follows：5UIpp (or between unit Every peak-to-peak value) and 0.1UIpp maximum jitter depend on jitter bandwidth；In 24 hours periods in 28UI and 15 minute interval The maximum network signal drift of 13UI；And the maximum phase transformation of 1.5UI or the instantaneous frequency displacement of 61ppm.In synchronous communication transmission, Unit gap is longest interval, and theoretically the significant interval duration of signal is all the integral multiple at this interval.These are crucial The equipment that specification enables telecom equipment manufacturers to develop ensures compatible.For the specification of drift, including for a long time, (24 is small When) and the drift of (15 minutes) in short term, it is defined relative to primary reference (PRS, Primary Reference Source) The drift of measurement, this has specific definition in ANSIT1.101.These specifications enable Telecommunications Engineer to develop filtering T1 nets The synchronized algorithm of shake, phase transformation and the drift of network interface, so as to extract meet global system for mobile communications (GSM, Global System for Mobile communications) timing need clock.

As previously described, the important rule drifted about in the T1 that T1 communication interfaces are directed to specified in T1.403 (§ 6.3.1.2) Fan Wei：＜ 13UIpp in 15 minutes；＜ 28UIpp in 24 hours.Other parts of the world include E1 used in Europe (2.048Mbps) circuit is also used similar standard regulation.G.823, ETSI specifications arrange in detail in table 2 (E1 communication interfaces) Go out these values -- 18 microsecond (μ s) in 1000 seconds.

The combination of one hard wired communications net and wireless communication networks defines the standard of T1 drifts relative to primary reference.Main reference Source (PRS) 2 is a part of public switch telephone network (PSTN, Public Switch Telephone Network) 4a, is led to T1 line 6a transmission is crossed, by mobile switching centre (MSC, Mobile Switching Center) 8, base station controller (BSC, Base StationController) 10, T1 line 6b, then by reciprocation function (IWF, InterWorkingFunction) gateway 12a, by PSTN 4b and IWF gateways 12b.Wherein, maximum end-to-end drift, PRS 2 peak-to-peak value must be shorter than 28 unit gaps (UI, Unit Interval).

It has been announced for the additional standard of timing T1 and E1 circuit.T1.101,7.2.1 section define timing T1 reference inputs, Regulation drift is 2 microseconds in 1 microsecond in 30 minutes (about 2000 seconds) and 72 hours (about 100,000 second).ETSI specifications G.823, table 12, Plesiochronous Digital hierarchy (PDH, Plesiochronous Digital Hierarchy) sync cap of definition With similar drift requirement：2 microseconds and 5.33 microseconds in 100,000 seconds in 2000 seconds.T1 and E1 timing circuits described above Standard is largely for by building integrated timing supply (BITS, Building Integrated Timing Supply) The timing circuit of T1 caused by unit and define, in fact these units can be found in all central offices. BITS is used to generate the clock of unusual high-quality, by clock be supplied in central office timing in need communication Equipment.These timings T1 circuit costs are high, therefore are not used in outside central office, and the timing that will not be used for GSM base stations should With.

GSM network the strict regulations timing demands of base transceiver station (BTS, Base Transceiver Station), BTS are For connecting the wireless points of mobile site or more typical mobile phone.The clock used in GSM base stations is necessary for base station Controller (BSC, Base Station Controller)/mobile switching centre (MSC, Mobile Switching Centre) Traceable clock, the absolute precision of clock are preferably higher than 1 50/1000000000ths (PPB, Parts PerBillion).BTS is using The T1 of recovery generates a recovered clock, this clock will meet the standard of ± 50ppb, cellular radio is extracted in the clock Frequency carrier timing and GSM are used to transmit the bit timing of bit stream.

The influence of clocking error is very significant.The error of ± 50ppb may result in the frequency shift (FS) of nearly ± 100Hz, this It is influenced for a 200kHz RF carrier wave little.But the error of ± 1000ppb (or ± a few millionths (ppm, Parts per billion)) error of 2kHz or 1% will be generated in RF channels, this will lead to adjacent-channel interference (non-compliance) incompatible with possible wireless frequency spectrum template.

But timing error on an rf carrier can cause interference with increase and radio wave is incompatible, determines in GSM bit streams When error can lead to network failure.GSM generates time division multiple acess access (TDMA, Time using the ± 50ppb clocks restored Division Multiple Access) frame, allow to encode at full speed using up to 8 mobile stations (MS, Mobile Station) Or it encodes to ensure mobile phone communication using 16 MS Half Speeds.GSM 05.01v5.4.0 are provided in Section 5, extraction ± 50ppb T1 clocks, for generate 3.69 microsecond bit periods, 0.577 millisecond of (ms) time slot, 4.515 milliseconds of TDMA frames, 120 milliseconds Multiframe (26 TDMA frames), 6.12 seconds superframes (51 multiframes) and 3 hours, 28 minutes, (2048 super for 53 seconds Hyperframes Frame).Mobile handoff depends on the synchronization of this time link, these timings are extracted in the T1 clocks of recovery.These The Doppler effect of MS is included in timing error, Doppler effect can explain the vehicle motion of high speed, and be changed into MS Significant timing error.During 1.9GHz, RF wavelength is 15 centimetres, and the vehicles are moved with 120,000 ms/h of speed, at this moment Due to Doppler effect it can be seen that the clocking error of apparent ± 117ppb.This error the, in addition ± 50ppb that GSM must have Error has reached ± 167ppb.Standard is defined in the valid timing error range of up to ± 300ppb and works, this error includes Switching starts the error caused by the Doppler effect before failure.GSM standard has been defined as, it is assumed that T1 clocked interfaces are When reaching ± 50ppb, support the vehicles and switched with the speed for being up to 250,000 ms/h.GSM attempts to provide all land The situation of vehicles switching；But it is including the speed per hour throughout Continental Europe without reaching 350,000 ms/h of super row Vehicle needs another version of GSM, referred to as GSM-R, with these unique needs of specific provision in this case.

GSM is an impressive mobile cellular network solution, but its operating condition is regarded and extracted from PSTN T1 clock qualities depending on.As long as T1 interfaces meet the defined drift and timing specification for the T1 circuits that communicate, network is with regard to energy It is enough to run well.However, if T1 circuits deviate timing specification, adverse consequences will be generated.Such as if T1 circuits exist Occurs the timing error of ± 200ppb in the short period of about 15 minutes, then in the vehicles with more than 100,000 ms/h When (about 60 mph.) speed is run, MS handover failure rates will increase.If similary period timing error is more than ± 250ppb, then in the case that vehicle motion speed is more than 50,000 ms/h, failed handoff scenario will be encountered.Most Eventually, if timing error is more than ± 300ppb, then all vehicle communications can all encounter mobile handoff failure, finally make Obtain the situation that network is only used for traffic on foot.

For many years, Network Operation Centre (NOC, Network Operations Center) develop monitoring handover failure and The tool to go offline, the comprehensive measurement correctly run for network or BTS.Under normal conditions, NOC is alerted using 3% drop rate Mobile handoff and call setup problem, these problems may be as caused by many factors.NOC staff is reminded in the alarm that goes offline Time critical inspection is proceeded by diagnose basic reason, this reason may be related to flow, it is also possible to related to network.Example Such as, the temporary growth that goes offline may imply that flow load is more than the design parameter of BTS websites.Antenna failure or misalignment can Cause the increase that goes offline.The failure of neighbouring BTS websites, i.e. power failure or mean free error time (MTBF, Mean TimeBetween Failure) error inadvertently can influence the traffic by the way that call business is switched to another website from a website. PSTN problems, such as T1 caused by configuration error lose, and can reduce communication capacity and cause the increase that goes offline.Finally, level is traced back The loss in source (stratum traceability) may lead to handover failure, herein in multiple switch or transmission device Any one is used to for T1 to be transmitted to the BTS websites for having enter into switching state from central office (CO, Central Office). Cellular carrier has developed the alarm of all these situations, can make network level excess drop rate be restored to reasonable value and By quick diagnosis, so as to be kept for relatively low mean repair time (MTTR, Mean Time To Repair).The puppet of cellular backhaul The introducing of line solution brings a series of new network problems to need to diagnose.Traditional TDM networks directly by T1 bit streams from MSC/BSC is transmitted to CO, meet well specification timing and data integrity demands, pseudo-wire solution is then different, it according to By clock recovery techniques at Ethernet (Ethernet)/IP groupings transmission and BTS websites.But the error of regulation T1TDM networks Rate is better than 10-9 to reach the minimum value of error-free operation in 72 hours, and the premise that packet network is then established is to pass through network channel It exchanges and realizes network resilience, do not consider caused by network topology change delay variation substantially or in these switchings Caused by packet loss.As described above, T1TDM networks are usually 3 days zero bit error rates of T1 circuit checks.Actual standard exists ITU-T suggest G.826 " Error performance parameters and objectives forinternational, (primary rate is primary by constant bit rate digital paths at or above the primary rate The error performance parameter and index of group rate more than international constant bit rate digital channel) " in provide, 27,000 are proposed in standard The bLock error rate (BBER, block BER) of every 500 kms of 2 × 10-4 or 1% in km channel, wherein block size are 4632 Bit (24 frame) is equivalent to the BER of 4.31 × 10-8.Therefore for T1TDM circuits, the target of 10-9 is considered as can be with Received performance.

Invention content

According to an embodiment of the invention, it provides and a kind of is estimated by filtering and handling the timing error of relevant pseudo-wire stream of packets The system and method for T1 timing errors, wherein T1 circuits are extracted from pseudo-wire stream of packets.Therefore, on the one hand, the present invention carries A kind of method has been supplied, for detecting packet jitter, situation and utilize these testing results essence that grouping phase transformation and grouping are drifted about It really alerts in the T1 for restoring or extracting and deposits error condition.

According to a further embodiment of the invention, the timing error of pseudo-wire Packet Data Network estimation and monitoring be by the present invention provide System and method complete.The embodiment provides one kind for estimating grouping drift and determining pseudo-wire stream of packets most The system and method for big time interval error (MTIE, Maximum Time Interval Error).Those skilled in the art's energy Enough understand that time interval error (TIE, Time IntervalError) is defined as the phase between measuring signal and reference signal Potential difference.MTIE is defined as the maximum TIE peak-to-peak values in certain observing time t.On the other hand, the present invention is also well described Packet jitter and phase transformation measure and are converted to the bit of T1 signals or the mode of timing error.Further, the present invention also carries A kind of system and method for the timing error for restoring pseudo-wire stream for detection are supplied.

Correspondingly, the embodiment provides a kind of for being for one or more pseudo-wire streams estimation grouping basic parameters System and method, these parameters include：Shake, phase transformation and drift.In addition, the embodiment of the present invention also proposes one kind based on these ginsengs The system and method for number alarm.These alarms are used to indicate is grouped transmission problem with diagnostic network, these problems cause from pseudo-wire The timing recovery errors of T1 signals extracted in stream.

According to another aspect of the invention, it is proposed that a kind of grouping MTIE specifications.The specification points out that the T1 clocks of extraction can exceed T1.403 (§ 6.3.1.2) wander specification that T1 communication interfaces are formulated, in 15 minutes intervals or in 24 hours intervals.Using repairing Positive parameter, this aspect of the invention can be used for being grouped for E1 (2.048Mbps) pseudo-wire streams and the E1 of extraction streams MTIE。

According to another aspect of the present invention, packet jitter and phase transformation of a kind of T1 signals to extraction with damaging influence are provided Analysis method.System and method the present invention further provides analyzing and proposing packet jitter and phase transformation, pass through the method energy Enough instructions and diagnostic network timing problems, these problems can inadvertently influence the T1 timings of extraction.Flutter effect, such as those It is shaken caused by switching from full duplex to semiduplex network path, shake can be received on grouping and made a significant impact, from And lead to edge buffering of packets.

According to even further aspect of the present invention, a kind of system and method for analyzing pseudo-wire stream of packets phase transformation, the party are provided Method points out that there is a kind of half zeitgeber can inadvertently influence pseudo-wire stream of packets, for example cause micro- shared synchronization shaken point Group stream or the backhaul factor that nearly synchronous (such as WiMAX) wireless frequency hopping can be used.

Correspondingly, the present invention proposes a series of new alarms and fault state, can be incorporated into Network Management System with Assist the detect and diagnose of Network status.These alarms can detect fault state as described above, these situations can be extensive Cause excessive MTIE and timing error in multiple data flow.

As will be appreciated by a person skilled in the art, although the present invention mainly uses the timing extracted from pseudo-wire stream of packets, It is the timing signal for being also generally applicable to other any extractions, such as IEEE 1588 precision clock agreement (PTP, Precision Time Protocol) [no matter version 1,2 or later version] (being equal to IEC 61588), this agreement carried using IP stream of packets Differential timing signal is taken to obtain high performance clock accuracy.Timing is used using pseudo-wire data flow or according to IEEE1588 Stream of packets, stream of packets can be handled to estimate to be grouped MTIE under both of these case, so as to estimate the MTIE of the T1 restored and Clocking error.

Further, it will be appreciated by those skilled in the art that there is presently no a kind of cost-effective timing sources to be supplied to BTS System, to meet or exceed the timing specification of ± 50ppb needed for GSM.Therefore, all clock sources, either crystal oscillation Device, temperature compensating crystal oscillator, voltage controlled oscillator or Temperature Controlled Oscillator and other types are required for locking MSC in CO Clock is to reach the standard of ± 50ppb.Therefore, according to even further aspect of the present invention, it is proposed that one kind is used for Detection and Extraction Clock source do not reach system and method when it is required.

Therefore the overall aspect of the present invention be just to provide it is a kind of by filter the timing error of pseudo-wire stream of packets related to handling come Estimate the system and method for T1 timing errors, wherein, T1 circuits are extracted from pseudo-wire stream of packets.This method will eliminate or Reduce above mentioned various problems.

According to the first aspect of the invention, a kind of method of estimation of the maximum time interval error of T1 data-signals is provided, it should T1 data-signals are extracted from pseudo-wire data flow, and this method includes the following steps：(a) the first of pseudo-wire grouping arrival time tN is established Beginning relative delay；(b) variation of monitoring relative delay tN；And (c) obtains maximum time according to the variation of the relative delay of monitoring Interval error (MTIE).According to the first aspect of the invention, the initial relative delay tN for establishing pseudo-wire grouping arrival time The step of include the use of multiple most fast groupings in pseudo-wire data flow, the step of variation of the monitoring relative delay tN, wraps It includes：Estimate the subsequent relative delay tN+1 of pseudo-wire grouping arrival time tN；And from the tN+1 of the multiple most fast grouping Subtract tN.

Further according in a first aspect, the step of monitoring the variation of relative delay tN includes：Difference between calculated for subsequent relative delay Value, to point out the maximum time interval error of Packet Data Network, wherein, described the step of obtaining maximum time interval error, includes Estimate maximum time interval error in the maximum time interval of 15 minutes or 24 hours.The first aspect of the present invention is further wrapped It includes：If the absolute value of tN-tN-1 is more than at least one scheduled threshold value, alarm is sent out, wherein, it is described at least one predetermined Threshold value can be expressed as bit period, microsecond or period any time generally.According to the first aspect of the invention, institute It states at least one scheduled threshold value and further comprises specification threshold value in T1.101, at least one scheduled threshold value is further Including T1 jitter-buffer threshold values, the T1 jitter-buffers threshold value includes about ± 128 micro- intervals (UI).The of the present invention On the one hand further comprise only when pre- more than at least one scheduled threshold value in the absolute value predetermined time cycle of tN-tN-1 Alarm can be just sent out during fixed number, wherein, the relative delay tN is obtained from pseudo-wire packet time stamp.It is according to the present invention In a first aspect, the relative delay tN is grouped in arrival time from pseudo-wire and obtains or the relative delay tN or from most quick Pseudo-wire is obtained in grouping arrival time or is obtained from the average retardation of pseudo-wire grouping arrival time.Further, first In aspect, the MTIE is with unit gap, microsecond or any other chronomere's formal definition generally.

According to the second aspect of the invention, a kind of method of estimation of the T1 clocking errors of T1 data-signals, T1 data letter are provided It number is extracted from pseudo-wire data flow, this method includes the following steps：(a) initial phase of pseudo-wire grouping arrival time tN is established to prolonging Late；(b) variation of monitoring relative delay tN；And (c) by estimate relative delay tN change rate estimate T1 clocking errors.According to Second aspect, the relative delay tN are obtained from pseudo-wire packet time stamp, and the relative delay tN is from during pseudo-wire grouping arrival Between in obtain the either relative delay tN and either obtain from most quick pseudo-wire grouping arrival time or be grouped from pseudo-wire It is obtained in the average retardation of arrival time.

According to second aspect, described the step of estimating T1 clocking errors, includes：Difference between calculated for subsequent relative delay, to point out The maximum time interval error of Packet Data Network；And the difference of calculated for subsequent MTIE values.It is described according still further to second aspect T1 clocking errors are with the formal definition of parts per billion or a few millionths.

According to the third aspect of the invention we, a kind of estimation of the evaluated error of pseudo-wire grouping present clock in Packet Data Network is provided Method, this method include：(a) initial maximum time interval error estimated value MTIE [n] and subsequent maximum time interval are determined Error estimate MTIE [n+1]；(b) leading in the difference predetermined time cycle by calculating MTIE [n] and MTIE [n+1] Number, determines present clock evaluated error；And (c) is continuously updated present clock evaluated error by repeating step (a) and (b), Until n reaches predetermined value.

According to the third aspect of the invention we, maximum time interval error estimated value was in 15 minutes or the maximum time interval of 24 hours Interior to determine, this method further comprises：If the absolute value of MTIE [n+1]-MTIE [n] is more than at least one scheduled threshold value, Then send out alarm.According to the third aspect, at least one scheduled threshold value can be expressed as unit gap parts per billion, A few millionths of unit gap or period any time generally；At least one scheduled threshold value includes the whole world The specification threshold value of mobile communication system (GSM) micro-base station sending and receiving stations (BTS).

According to the third aspect of the invention we, the specification threshold value of the GSM micro-base stations sending and receiving stations is about +/- 50/1000000000ths, The specification threshold value of pico- (pico) BTS of middle GSM is about +/- 100/1000000000ths.The third aspect of the present invention further comprises only It is more than at least one scheduled scheduled number of threshold value to have when the absolute value predetermined time cycle of MTIE [n+1]-MTIE [n] is interior Shi Caihui sends out alarm, wherein the step of determining present clock evaluated error includes：Calculate MTIE [n] and MTIE [n+1] Difference predetermined time cycle in integration.

According to the fourth aspect of the invention, a kind of estimation side of pseudo-wire grouping maximum time interval error in Packet Data Network is provided Method, this method include：(a) estimate the initial relative delay tN of multiple most fast groupings in pseudo-wire data flow, wherein n's is initial Value is set as zero；(b) timing of T1 data-signals extracted from 1588 accurate timing sources of IEEE is monitored；(c) by using initial phase To delay tN as zero reference maximum time interval error reference value, the T1 numbers extracted from 1588 accurate timing sources of IEEE are verified It is believed that number timing, and estimate the subsequent relative delay tN+1 of the multiple most fast grouping, tN subtracted from tN+1, then The timing of T1 data-signals is further verified using the difference of adjacent relative delay, if the difference of adjacent relative delay surpasses Scheduled threshold value is crossed, then verifies the timing error of T1 data-signals extracted from 1588 accurate timing sources of IEEE.

According to the fourth aspect of the invention, the step of the relative delay tN of multiple most fast groupings in the estimation pseudo-wire data flow Suddenly include：Estimate relative delay, and further comprise if the absolute value of tN+1-tN surpasses using 1588 accurate timing sources of IEEE At least one scheduled threshold value is crossed, then sends out alarm.

According to the fourth aspect of the invention, at least one scheduled threshold value be bit period or microsecond, it is described at least one Scheduled threshold value includes the specification threshold value of T1.101 or at least one scheduled threshold value includes T1 jitter-buffer thresholds Value.

Further according to the fourth aspect of the invention, the T1 jitter-buffers threshold value includes about ± 128 micro- intervals (UI), And further comprise only when scheduled more than at least one scheduled threshold value in the absolute value predetermined time cycle of tN+1-tN Alarm can be just sent out during number.

According to the fifth aspect of the invention, a kind of system for the maximum time interval error for being used to estimate T1 data-signals is provided, The T1 data-signals are extracted from pseudo-wire data flow, which includes：It is configured as receiving the T1 data-signals of pseudo-wire data flow Receiver, wherein T1 data signal receivers include T1 data signal processors, and wherein T1 data signal processors are configured as (a) the initial relative delay of pseudo-wire grouping arrival time tN is established, the variation of (b) monitoring relative delay tN and (c) are according to monitoring Relative delay variation, obtain maximum time interval error (MTIE).

According to the fifth aspect of the invention, the T1 data signal processors are configured to using in pseudo-wire data flow Multiple most fast groupings establish the initial relative delay tN of pseudo-wire grouping arrival time, wherein, T1 data signal processors are into one Step is configured as the subsequent relative delay tN+1 of estimation pseudo-wire grouping arrival time tN, from the tN of the multiple most fast grouping TN is subtracted in+1, to monitor the variation of relative delay tN.

According to the fifth aspect of the invention, if at least one of shake, drift and phase transformation value are kept at or below ANSI The normal value of corresponding shake, drift or phase transformation in T1.403-1999, then relative delay tN somewhat constants, wherein T1 data are believed Number processor is configured to estimate maximum time interval error in the maximum time interval of 15 minutes or 24 hours.

According still further to the fifth aspect of the present invention, if T1 data signal processors are configured to tN-tN-1's Absolute value is more than at least one scheduled threshold value, then sends out alarm.According to the 5th aspect, at least one scheduled threshold value energy Enough it is expressed as bit period, microsecond or period any time generally, at least one scheduled threshold value is included in T1.101 Specification threshold value or at least one scheduled threshold value include T1 jitter-buffer threshold values, and wherein T1 jitter-buffers threshold value includes About ± 128 micro- intervals (UI).

According to the fifth aspect of the invention, T1 data signal processors are configured to only when the absolute value of tN-tN-1 When in predetermined time cycle being more than the scheduled number of at least one scheduled threshold value, alarm, the relative delay can be just sent out TN is obtained from pseudo-wire packet time stamp.

According to the fifth aspect of the invention, the relative delay tN, which is grouped from pseudo-wire in arrival time, obtains or described opposite Delay tN is obtained from the arrival time of most quick pseudo-wire grouping or is obtained from the average retardation of pseudo-wire grouping arrival time It arrives, wherein the MTIE is with unit gap, microsecond or any other chronomere's formal definition generally.

According to the sixth aspect of the invention, a kind of system for the T1 clocking errors for being used to estimate T1 data-signals, the T1 numbers are provided It is believed that number being extracted from pseudo-wire data flow.The system includes：It is configured as receiving the T1 data signal receivers of pseudo-wire data flow, Wherein the T1 data signal receivers include T1 data signal processors, and T1 data signal processors therein are configured as：(a) The initial relative delay of pseudo-wire grouping arrival time tN is established, the variation of (b) monitoring relative delay tN, (c) is opposite by estimating Postpone the change rate estimation T1 clocking errors of tN.

According to the sixth aspect of the invention, the relative delay tN is obtained from pseudo-wire packet time stamp or described opposite is prolonged Slow tN, which is grouped from pseudo-wire in arrival time, to be obtained.Further according to the 6th aspect, the relative delay tN or from most quick pseudo- Line is obtained in grouping arrival time or is obtained from the average retardation of pseudo-wire grouping arrival time.

According to the sixth aspect of the invention, the T1 data signal processors are configured between calculated for subsequent relative delay Difference, estimate T1 clocks to obtain the difference of the maximum time interval error of Packet Data Network and calculated for subsequent MTIE values Error.According to the 6th aspect, the T1 clocking errors are with the formal definition of parts per billion or a few millionths.According to this hair The 7th bright aspect provides a kind of system for being used to estimate pseudo-wire grouping present clock evaluated error in Packet Data Network, this is System includes：It is configured as receiving the T1 data signal receivers of pseudo-wire data flow, wherein T1 data signal receivers include T1 numbers According to signal processor, and T1 data signal processors are configured as：(a) initial maximum time interval error estimated value MTIE is determined [n] and subsequent maximum time interval error estimated value MTIE [n+1], (b) is by calculating the difference of MTIE [n] and MTIE [n+1] The derivative being worth in predetermined time cycle, determines present clock evaluated error, and (c) is determined by repeating in step (a) and (b) Process is continuously updated present clock evaluated error, until n reaches predetermined value.According to the seventh aspect of the invention, it is described most Big time interval error estimated value determines in the maximum time interval of 15 minutes or 24 hours, and T1 data signal processors are into one If the absolute value that step is configured as MTIE [n+1]-MTIE [n] is more than at least one scheduled threshold value, alarm is sent out.According to The seventh aspect of the present invention, at least one scheduled threshold value can be expressed as between the parts per billion of unit gap, unit Every a few millionths or period any time generally.According to the seventh aspect of the invention, it is described at least one predetermined Threshold value include the specification threshold values of global system for mobile communications (GSM) micro-base station sending and receiving stations (BTS), wherein the GSM micro-base stations The specification threshold value of sending and receiving stations is about +/- 50/1000000000ths, further, the specification threshold value of pico- (pico) BTS of the GSM +/- 100/about 1000000000ths.

According to the seventh aspect of the invention, the T1 data signal processors be configured to only when MTIE [n+1]- Announcement can be just sent out when in the absolute value predetermined time cycle of MTIE [n] being more than the scheduled number of at least one scheduled threshold value Alert, the T1 data signal processors are configured to calculate the difference of MTIE [n] and MTIE [n+1] in week predetermined time Integration in phase, to determine the evaluated error of present clock.

According to the eighth aspect of the invention, it provides and a kind of to estimate that pseudo-wire grouping maximum time interval error is in Packet Data Network System, the system include：It is configured as receiving the T1 data signal receivers of pseudo- data flow, wherein the T1 data signal receiver packets Data signal processor containing T1.Wherein the T1 data signal processors are configured as multiple most fast in (a) estimation pseudo-wire data flow The initial value of the initial relative delay tN of speed grouping, n are set as zero, the T1 numbers that (b) monitoring is extracted from 1588 accurate timing sources of IEEE It is believed that number timing and (c) by using initial relative delay tN as zero reference maximum time interval error, verify from IEEE The timing of the T1 data-signals of 1588 accurate timing sources extraction, and estimate the subsequent relative delay tN of the multiple most fast grouping + 1, tN is subtracted from tN+1, and the timings of T1 data-signals is further verified using the difference of adjacent relative delay, if phase The difference of adjacent relative delay is more than scheduled threshold value, then verifies the T1 data-signals extracted from IEEE1588 accurate timings source Timing error.

According to the eighth aspect of the invention, the T1 data signal processors are configured to accurate using IEEE 1588 The relative delay tN of multiple most fast groupings in timing source estimation pseudo-wire data flow, the T1 data signal processors are further If the absolute value for being configured as tN+1-tN is more than at least one scheduled threshold value, alarm is sent out.

According to the eighth aspect of the invention, at least one scheduled threshold value can be bit period or microsecond, it is described At least one scheduled threshold value includes T1 including the specification threshold value in T1.101 or at least one scheduled threshold value and shakes Buffer threshold.According to the eighth aspect of the invention, the T1 jitter-buffers threshold value includes about ± 128 micro- intervals (UI)。

According to the eighth aspect of the invention, the T1 data signal processors are configured to exhausted only as tN+1-tN Alarm can be just sent out during in value predetermined time cycle being more than the scheduled number of at least one scheduled threshold value.

Specific embodiment

Description below in relation to preferred forms expected from the present invention is not intended to limit the present invention, and just for the sake of description The General Principle of the present invention.

Preferred embodiment according to the present invention, the pseudo-wire grouping MTIE and PPB estimators provided, may be used to indicate that the T1 of extraction Clock may exceed the wander specification of T1 communication interfaces, as in T1.403 (§ 6.3.1.2) between one or more 15 minutes Every or 24 hours interval in wander specification.Grouping MTIE estimators in the preferred embodiment of the present invention are assumed in the network operation Static period in most fast grouping have constant network propagation delay.Grouping MTIE in the preferred embodiment of the present invention Estimator selectively handles the time difference between RTP packet times stamp, and the timestamp is in T1 line timing node (timed Node it is labeled when) generating grouping.Labeled timestamp indicates that grouping is received by respective pseudo-wire timing node Time.Clock is used for generating the stamp packet of T1 signal times when generating packet.If a clock or other clocks Than another clock operation faster (whereas slower), then MTIE will show these errors.In the embodiment of the present invention, mesh Mark is by two clock locks, and the timing difference between two such clock will be reduced significantly or preferably be eliminated.When two When the clock of a node synchronizes, the difference between timestamp is constant.If clock is not locked, the time difference will be according to differential clocks Error and increase or decrease.T1MTIE is the peak value of difference in period demand.The derivative of MTIE is used to estimation T1 clocking errors. As described above, the embodiment of the present invention and discussion herein are directly against T1 pseudo-wire data-signals；But people in the art's energy Enough to understand, embodiment discussed herein can also be used for E1 pseudo-wires data-signal and/or the T1 pseudo-wire data for bundling/decoupling Stream.The influence of the interchanger of incorrect configuration, the interchanger are programmed to unintentionally half-duplex operation rather than full duplex operation.No The influence for the interchanger being correctly configured, the interchanger are programmed to unintentionally 100Mbps half-duplexs operation rather than full duplex fortune Row.What the longitudinal axis represented is the opposite packetization delay (shake) by interchanger measured as unit of UI, when being of horizontal axis representative Between (hundreds of microseconds).Each point shows the arrival of pseudo-wire grouping.Programming link-speeds are changed into half-duplex when institute from full duplex Caused anomaly link behavior.Part abnormal behaviour is to be grouped slowly, is labeled as i, ii, iii and iv, although its property is the period Property, but these slow groupings, which can be used the timing of most fast grouping to measure software, to be filtered out.What is be equally revealed goes back The abnormal behaviour of burst " v " and " vi " caused by having when becoming half-duplex from full duplex in relation to fast grouping.These points Group fast burst can influence Timed Recovery and cause variation, these variation can only through the embodiment of the present invention in MTIE estimate Device is found out.Therefore, in the present embodiment, interface becomes semiduplex network change from full duplex can cause the change of packetization delay Change, alarm is sent out so as to cause MTIE.MTIE alarms generate simultaneously with network change so that network engineers can notice rapidly peace Dress personnel they have modified influence clock recovery parameter.Correspondingly, in control loop it cannot be guaranteed that the condition that T1MTIE needs Under can detect clock failure alert and if send out alarm, be that the various embodiments stated in the present invention show other one Kind ability.

Therefore, the first aspect of the present invention is used there is provided the selectivity of most fast grouping or more specifically, those have There is the grouping of minimum Network Transmission Delays.Those skilled in the art are known, network delay can with the variation of network load and Change, such as higher network load can cause obvious packet delay.Similary those skilled in the art are known, and grouping is prolonged Slow average value and maximum value can also increase with the increase of network load.When network load is close to 100%, averagely and most Big grouping propagation time delay will exponentially form increase.Nevertheless, minimum grouping transmission time is in most of nets It is held essentially constant under network loading condition, in addition to the special circumstances close to 100% load.

Preferred embodiment in the present invention, the quiescent value of t0 postpone zero packets as in given network topology structure Maximum time interval (MTIE) error an absolute reference point.When the topological structure of network changes, new t0 values It will be recalculated and as the reference point of new zero packets MTIE.

Zero packets MTIE-t0 is a statistical parameter, by packetization delay sample as much as possible necessary to processing in the hope of most The fine estimation of small packetization delay and calculate and get.Once the t0 of static network topology is determined, control algolithm can adjust extensive Multiple T1 clocks represent basic zero packets MTIE to keep t0 constant.Therefore, according to the system in the embodiment of the present invention and method T0 can constantly be reevaluated.T0's reevaluates the test constantly being recorded as to MTIE, and is used to adjust controlled The clock of equipment (such as BTS).

As is understood by a person skilled in the art, it can estimate t0 with different algorithms.The example of one of them this algorithm Son is to optimize clock by operating proportional/integral/derivative (PID) control loop.In the embodiment of the present invention, MTIE estimators Show that but PID or other control algolithms reach the swing of timestamp farthest how many T1 time according to grouping.Design is different Algorithm be in order to which the relative time difference for the data flow for keeping receiving is smaller compared with t0, limit MTIE every 24 hours 28UI. According to the present invention, if there is any offset beyond this boundary implies, then it can be concluded that data are fed back to PID or other controls Circuit processed is improperly.

As is understood by a person skilled in the art, essentially all control algolithm all using model come control system, these Model is used for by control system and the data for control system received.These models are linearly or nonlinearly.One Linear control system can be a PID controller, feedback control signal therein or the error with constant KP and (tN-t0) Product is proportional or error from (tN-t0) about the product of the differential of time and another different constant Kd into than Example is proportional to the product of the integration of the error of (tN-t0) and constant Ki.Nonlinear control system is similar to Linear Control System, unlike, such as the gain of control loop is that exponentially form increases based on error (tN-t0), so for example Proportional gain is KP when middle error signal (tN-t0) ＜ 10, when (tN-t0) error signal >=10 proportional gain increase A length of 2*KP.For example, the model of crystal (receiving clock for generating) can be with the formal definition number control of parts per billion Value processed and the allowed band of corresponding relative frequency variation.The nonlinear model of timing packetization delay sample assumes network topology Structure change can cause being altered in steps for network delay.When other non-linear aspects can solve periodically to be grouped and is other similar Control micro- problem of shaking of grouping.If model is correct, control system will work and maintains t0 in the specification of flow T1 as scheduled.Control The good normal operation worked in the range of defined MTIE and PPB needed for T1 circuits in circuit processed.The present invention's is excellent It is a phase lock control system to select the control loop in embodiment, and the particular electrical circuit of one embodiment in invention is at first The maximum time interval error of current group in time cycle.

More than MTIE threshold values or more than the reason of not being notified that NOC clocking errors is alerted caused by PPB estimated values, only inform There is the clock of clocking error and recovery and be unsatisfactory for code requirement.There is a kind of alarm situation that can be used to help determine event by NOC Hinder reason.This is situation about often having, and basic reason is that NOC intervenes or the change of circuit directly results in, if there is report Alert to occur, these variations can be eliminated promptly.

An alternative embodiment of the invention provides a kind of system that T1 timing errors are inferred according to packet MTIE estimators And method.The system and method for being used for inferring in the embodiment of the present invention are using the transmission function in control algolithm in combination with warp The grouping MTIE estimated values of calculating are crossed to estimate the MTIE values of T1.Then, the MTIE values of the T1 of estimation are just used to setting alarm Threshold value.

The typical control system of one embodiment of the present of invention, wherein for pseudo-wire data stream recovery timing from pseudo-wire data flow Middle extraction.Pseudo-wire data flow in control system is used as timing source, and is timed according to pseudo-wire unit 4, and pseudo-wire unit 4 Local timing is carried out according to line interface unit (LIU, Line Interface Unit) 4.When data enter LIU 2, one T1 data clocks give each mark data packets timestamp.Then T1 data pass through nothing as packets of data via network 6 Line or cable network are transmitted.And restored at converter 8 and LIU 10.LIU 10 utilizes the T1 data clocks of itself Come for the mark data packets timestamp restored, relative to T1 data clocks are sent, the T1 data clocks of LIU 10 are freely Operation.The change rate of difference illustrates whether one of clock is faster than another clock between two clock time stamps.If Δ t increases, then means to receive clock operation comparatively fast, if Δ t is reduced, means that the operation of local reception clock is slower.Also Comprising typical proportional integral differential (PID, a Proportional Integral Derivative) controller, form PLL control systems 12.A part for control system 12 is monitoring function, including there are two taps (tap)：First limiter 14, for sending out alarm when MTIE situations are excessive；And derivative functional block 16, the second limiter 18 is connected thereafter, second limit Device 18 processed is used to that alarm can be sent out in the case of excessive clocking error.In the preferred embodiment of the present invention, clocking error is more than Alarm can be sent out during the threshold of about 100ppb.

The typical control system of one embodiment of the present of invention, wherein for pseudo-wire data stream recovery timing from IEEE 1588 It is obtained in timing local clock 26, the T1 of recovery timing is obtained from 1588 local clocks 26 of IEEE rather than from pseudo-wire stream. 1588 local clocks 26 of IEEE are relied on exchanges timed message and control with 1588 timing sources 24 of IEEE in a network.IEEE 1588 timing sources 24 trace layer (stratum traceable) timing reference, therefore final result using identical with LIU 2 It is exactly that the IEEE1588 clocks restored in pseudo-wire case 20 should possess identical timing with network.

Embodiment in the present invention can realize as a computer program, can be embodied in it is any can be used it is computer-readable Medium or the connection with instruction execution system, device or equipment, such as computer based system, containing the system of processor or its He can be obtained at instruction execution system, device or equipment and the system of execute instruction." computer-readable Jie used herein Matter " can be it is any can accommodate, store, communicate, propagate, or transport program thereby or with instruction execution system, device or equipment The device being connected.Computer-readable medium can be electronics, magnetic, optical, electromagnetism, infrared or semiconductor System, device, equipment or propagation medium, be merely illustrative above it is not limited to this.More computer-readable mediums Specific example (non-exhaustive inventory) may include the following contents：Have the electric connector of one or more line, portable computer diskette, Random access memory (RAM), read-only memory (ROM), Erasable Programmable Read Only Memory EPROM (EPROM or flash memory), optical fiber With portable compact disc (CDROM).

Above with reference to the embodiment of the present invention, invention has been described, however those skilled in the art easily think It arrives, without departing from the spirit and scope of the present invention, the present invention can also have other specific forms, and implement more than being not limited to The described situation of example, the embodiment of the present invention is merely exemplary rather than limitation of the present invention in any way.This hair Bright range is defined by appended claims and its equivalent replacement rather than is defined by above description.

Claims (10)

1. a kind of method of estimation of the maximum time interval error of T1 data-signals, the T1 data-signals are carried from pseudo-wire data flow It takes, which is characterized in that this method includes the following steps：A, the initial relative delay of pseudo-wire grouping arrival time tN is established；B, it supervises Control the variation of relative delay tN；And c, maximum time interval error MTIE obtained according to the variation of the relative delay of monitoring.

2. the method as described in claim 1, which is characterized in that the initial phase for establishing pseudo-wire grouping arrival time tN is to prolonging Slow step includes the use of multiple most fast groupings in pseudo-wire data flow.

3. the method as described in claim 1, which is characterized in that the step of variation of the monitoring relative delay tN includes：Estimate Count the follow-up relative delay tN+1 of pseudo-wire grouping arrival time tN；And subtract tN from the tN+1 of the multiple most fast grouping.

4. the method as described in claim 1, which is characterized in that the step of variation of the monitoring relative delay tN includes：Meter The difference between follow-up relative delay is calculated, to obtain the maximum time interval error of Packet Data Network.

5. the method as described in claim 1, which is characterized in that described the step of obtaining maximum time interval error is included in 15 Estimation maximum time interval error in the maximum time interval of minute or 24 hours.

6. the method as described in claim 1, which is characterized in that the method further includes：If the absolute value of tN-tN-1 More than at least one scheduled threshold value, then alarm is sent out.

7. method as claimed in claim 6, which is characterized in that at least one scheduled threshold value can be expressed as bit week Phase, microsecond or period any time generally.

8. method as claimed in claim 6, which is characterized in that at least one scheduled threshold value includes the rule in T1.101 Model threshold value.

9. method as claimed in claim 6, which is characterized in that at least one scheduled threshold value includes T1 jitter-buffers Threshold value.

10. method as claimed in claim 6, which is characterized in that the T1 jitter-buffers threshold value is micro- including about ± 128 It is spaced UI.