Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Patent
1999-07-26
2000-12-19
DeCady, Albert
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
714752, 714704, 714777, 714782, 714712, H03M 1300
Patent
active
061638722
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a monitoring OAM cell assisted method enabling continuous intrasystem determination of bit errors which have occurred in ATM useful cells with a useful information field and a cell head on an ATM transmission link.
In a known method of this kind (Andreas Wolf, `Leistungsmessungen in ATM-Netzen`, NTZ volume 47, issue 6, 1994, pages 408 to 413) monitoring OAM cells are used for continuous intrasystem monitoring of an ATM transmission link. For this purpose, the monitoring OAM cells are introduced into the cell stream of the ATM useful cells. EDC data (EDC: error detecting code) contained in the useful data of said monitoring OAM cells allows the detection of bit errors in ATM useful cells. In practice, only ATM useful cells with a selected target address in the cell head are used. According to the above-quoted prior art, the useful data of the monitoring OAM cells furthermore include ECB data (ECB: error check bits) allowing the detection of bit errors in the monitoring OAM cell in question. To be more precise, this is the cyclic supplementation of an Abramson code which makes it possible to detect up to three bit errors. If, during a verification of the ECB data, errors are detected in one of the monitoring OAM cells, such cell is eliminated and not used for evaluation.
BRIEF SUMMARY OF THE INVENTION
It is the object of the present invention to provide a method for detecting bit errors which have occurred in ATM useful cells on an ATM transmission link, which method allows the detection of almost all bit errors in ATM useful cells with the selected target address in the cell head.
This object is accomplished according to the invention in that the monitoring OAM cells which were recognized as having been transmitted defectively are corrected by means of their further control bits and thus converted into error-free monitoring OAM cells if a single bit error or a single double bit error has occurred in the one control bits and/or in the further control bits of the monitoring OAM cell. The one control bits of these monitoring OAM cells are then used for detecting the bit errors which have occurred in the received ATM useful cells with the selected target address in the cell head.
The essential advantage of this method is that--after the correction of the monitoring OAM cells which were recognized as having been transmitted defectively--a larger total of monitoring OAM cells is available for evaluation, making it possible to more reliably determine bit errors in the ATM useful cells with the selected target address in the cell head than by means of the known method.
Abramson encoding the monitoring OAM cells only allows the correction of one bit error or one double bit error in these cells. If it is desired to be able to also correct monitoring OAM cells which contain more than one bit error or more than one double bit error, it is considered advantageous within the scope of a further development of the method according to the invention to generate additional control bits by additionally encoding the one control bits, said additional control bits then being transmitted together with the one control bits and the further control bits in the monitoring OAM cells, said additional control bits being used for detecting defectively transmitted monitoring OAM cells and/or for correcting the monitoring OAM cells recognized as having been transmitted defectively.
Since the monitoring OAM cells fed into the cell stream are of a predetermined constant cell length, it is considered advantageous to use a block code for additional encoding.
A very efficient type of encoding is BCH encoding (BCH: Bose Chaudhuri Hocquenghem) or CCF encoding (CCF: cross-correlation function) and it is thus considered advantageous to use a CCF code or a BCH code as the block code.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
As an illustration of the invention, the (only) FIGURE is a block diagram view of an embodiment of an arrangement for performing the method according to the
REFERENCES:
patent: 4763331 (1988-08-01), Matsumoto
patent: 5321688 (1994-06-01), Nakano et al.
patent: 5337307 (1994-08-01), Sato et al.
patent: 5440565 (1995-08-01), Miyamoto et al.
patent: 5513191 (1996-04-01), Takechi et al.
patent: 5541926 (1996-07-01), Saito et al.
patent: 5570357 (1996-10-01), Tetering et al.
patent: 5579303 (1996-11-01), Kiriyama
patent: 5627821 (1997-05-01), Miyagi
patent: 5633868 (1997-05-01), Baldwin et al.
patent: 5634097 (1997-05-01), Ashi et al.
patent: 5675578 (1997-10-01), Gruber et al.
patent: 5790525 (1998-08-01), Ono et al.
patent: 5886989 (1999-03-01), Evans et al.
patent: 5914966 (1999-06-01), Bochereau
patent: 6061825 (2000-05-01), Wolf
Park (Bi-Directional 3-Port ATM Cam Supporting Fast Look-Up and Reduced Cycle Time. IEEE, Oct. 1996).
Chan et al.(Preemptive Reservation Arbitrated Access for Transporting Variable Bit Rate Isochronous Traffic Over Dual Bus M.A.N., IEEE, Mar. 1997).
De'cady Albert
Gray Francis I
Lamarre Guy
Lenihan Thomas F.
Textronix, Inc.
LandOfFree
Monitoring OAM cell assisted method of detecting bit errors occu does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Monitoring OAM cell assisted method of detecting bit errors occu, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Monitoring OAM cell assisted method of detecting bit errors occu will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-278266