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Re: BER value of TLV in LMP-WDM
Tomo,
Bit Error defect detectors in SDH, SONET and OTN are defined in G.806.
SDH has two alternative detector sets (see below) with different parameters:
a) EXC_X in range 10-3, 10-4 and 10-5, DEG_X in range 10-5, 10-6, 10-7, 10-8,
10-9
b) DEGM in range 2..10 and DEGTHR in range 0..100% or 0..N
SONET uses alternative a) detector types, while most AU-4 based SDH uses
alternative b) detector types (refer to ETSI EN 300 417-1-1.
OTN will only use alternative b) detector types.
Regards,
Maarten
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Text from G.806:
6.2.3 Signal quality supervision
6.2.3.1 Generic behaviour
Signal quality supervision in general monitors the performance of a trail. If
the performance falls below a certain threshold this might activate a defect.
For the generic performance monitoring process see section 8.3.
For networks where the network operator assumes a Poisson distribution of
errors, an excessive error defect and a degraded signal defect are to be
detected.
For networks where the operator assumes a bursty distribution of errors, a
degraded signal defect is to be detected. The excessive error defect, for this
case, is assumed to be false.
The applicability of the two is in the province of the regional standards.
6.2.3.1.1 Excessive error (dEXC) and degraded signal defects (dDEG) assuming
Poisson distribution of errors Excessive error and degraded signal defects are
to be detected according to the following process:
An excessive error defect (dEXC) shall be detected if the equivalent BER exceeds
a preset threshold of 10-x, x = 3, 4 or 5. The excessive error defect shall be
cleared if the equivalent BER is better than 10-(x+1).
With BER >= 10-x the probability of defect detection within the measuring time
shall be ³ 0.99.
With BER <= 10-(x+1) the probability of defect detection within the measuring
time shall be £ 10-6.
With BER >= 10-x the probability of defect clearing within the measuring time
shall be £ 10-6.
With BER <= 10-(x+1) the probability of defect clearing within the measuring
time shall be ³ 0.99.
A degraded signal defect (dDEG) shall be detected if the equivalent BER exceeds
a preset threshold of 10-x, x = 5, 6, 7, 8 or 9. The degraded signal defect
shall be cleared if the equivalent BER is better than 10-(x+1).
With BER >= 10-x the probability of defect detection within the measuring time
shall be ³ 0.99.
With BER <= 10-(x+1) the probability of defect detection within the measuring
time shall be £ 10-6.
With BER >= 10-x the probability of defect clearing within the measuring time
shall be £ 10-6.
With BER <= 10-(x+1) the probability of defect clearing within the measuring
time shall be ³ 0.99.
Maximum detection and clearing time requirements for the BER calculations for
SDH are listed in Table 6-4, Table 6-5 and Table 6-6. For all other signals
these values are for further study.
NOTE - The specification in the 94 revision of ITU-T Recommendation G.783 [9]
could have been interpreted as listed in Table 6-7.
TABLE 6-4/G.806
Maximum detection time requirements for VC-4 and VC-3
Detector Actual BER
threshold >=10-3 10-4 10-5 10-6 10-7 10-8 10-9
10-3 10 ms
10-4 10 ms 100 ms
10-5 10 ms 100 ms 1 s
10-6 10 ms 100 ms 1 s 10 s
10-7 10 ms 100 ms 1 s 10 s 100 s
10-8 10 ms 100 ms 1 s 10 s 100 s 1 000 s
10-9 10 ms 100 ms 1 s 10 s 100 s 1 000 s 10 000 s
TABLE 6-5/G.806
Maximum detection time requirements for VC-2, VC-12 and VC-11
Detector Actual BER
threshold >=10-3 10-4 10-5 10-6 10-7 10-8
10-3 40 ms
10-4 40 ms 400 ms
10-5 40 ms 400 ms 4 s
10-6 40 ms 400 ms 4 s 40 s
10-7 40 ms 400 ms 4 s 40 s 400 s
10-8 40 ms 400 ms 4 s 40 s 400 s 4 000 s
TABLE 6-6/G.806
Clearing time requirements
Detector Set/Clear values Multiplex section VC-2
threshold associated with VC-4 VC-12
detector threshold VC-3 VC-11
10-3 10-3/10-4 10 ms 40 ms
10-4 10-4/10-5 100 ms 400 ms
10-5 10-5/10-6 1 s 4 s
10-6 10-6/10-7 10 s 40 s
10-7 10-7/10-8 100 s 400 s
10-8 10-8/10-9 1 000 s 4 000 s
10-9 10-9/10-10 10 000 s
TABLE 6-7/G.806
Alternative interpretation of maximum detection and clearing time requirements
in the 94 revision of ITU-T Recommendation G.783 [9]
Detector threshold Multiplex section VC-2
VC-4 VC-12
VC-3 VC-11
10-3 10 ms 40 ms
10-4 100 ms 400 ms
10-5 1 s 4 s
10-6 10 s 40 s
10-7 100 s 400 s
10-8 1 000 s 4 000 s
10-9 10 000 s
6.2.3.1.2 Excessive error (dEXC) and degraded signal defects (dDEG) assuming
Bursty distribution of errors
The excessive error defect is not defined, and dEXC is assumed to be false.
The degraded signal defect (dDEG) shall be declared if DEGM consecutive bad
intervals (interval is the one second period used for performance monitoring)
are detected. An interval is declared bad if the percentage of detected errored
blocks in that interval or the number of errored blocks in that interval >=
Degraded Threshold (DEGTHR).
NOTE 1 - For the case of dDEG in the MSn layer, the errored block is equal to a
BIP violation.
The degraded signal defect shall be cleared if M consecutive good intervals are
detected. An interval shall be declared good if the percentage of detected
errored blocks in that interval or the number of errored blocks in that interval
< DEGTHR.
The parameter DEGM shall be provisionable in the range 2 to 10.
The parameter DEGTHR shall be provisioned either as a percentage or either as a
number of errored blocks. When based on a percentage, it shall be in the range 0
< DEGTHR <= 100%. When based on a number of errored blocks, it shall be in the
range 0 < DEGTHR <= Number of blocks in the interval.
NOTE 2 - When using percentage, for higher rate interfaces, one per cent is
equal to a large number of blocks. For example, in an STM-16 interface, 1% is
equal to a step of 30 720 blocks in the interval for the multiplex section.
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