PM5312STTX Datasheet, PDF (38/140 Pages) PMC-Sierra, Inc – SONET/SDH TRANSPORT OVERHEAD TERMINATING TRANSCEIVER TELECOM STANDARD PRODUCT

DATA SHEET
PMC-930829
ISSUE 5
PM5312 STTX
SONET/SDH TRANSPORT TERMINATING TRANSCEIVER
Once the external serial to parallel converter has found byte-alignment, the
RSOP block monitors for the next occurrence of the framing pattern 125µs later.
The block declares frame alignment when either all A1 and A2 bytes are seen
error-free or when only the first A1 byte and the first four bits of the A2 byte are
seen error-free. Depending upon the operating mode, the first algorithm
examines 2 bytes (A1,A2) in STS-1 mode, 6 bytes (A1A1A1,A2A2A2) in STS-
3/STM-1 mode, or 24 bytes (A1A1A1A1A1A1 A1A1A1A1A1A1,
A2A2A2A2A2A2A2A2A2A2A2A2) in STS-12/STM-4 mode.
The second algorithm examines only the first occurrence of A1 and the first four
bits of the first occurrence of A2 in the sequence, regardless of the operating
mode. Once in frame, the RSOP block monitors the framing pattern sequence
and declares OOF when one or more bit errors in each framing pattern are
detected for four consecutive frames. Again, depending upon the operating
mode selected the first algorithm examines all 2, 6, or 24 framing bytes for bit
errors each frame, while the second algorithm examines only the A1 byte and the
first four bits of the A2 byte (i.e. 12 bits total) during each frame.
The performance of these framing algorithms in the presence of bit errors and
random data is robust. When looking for frame alignment the performance of
each algorithm is dominated by the alignment algorithm used in the external
receive interface for the STS-3/STM-1 and STS-12/STM-4 operating modes.
Typical probability of falsely framing to random data is less than 0.00001% for
either algorithm.
When the STTX is operating in STS-1 mode either algorithm still provides less
than 0.00001% probability of falsely framing to random data. Once in frame
alignment, the STTX continuously monitors the framing pattern. When the
incoming stream contains a 10^-3 BER, the first algorithm provides a 99.75%
probability that the mean time between OOF occurrences is 4 minutes in STS-1
mode, 14 seconds in STS-3/STM-1 mode, and 1.3 seconds in STS-12/STM-4
operating mode. The second algorithm provides a 99.75% probability that the
mean time between OOF occurrences is 7 minutes, regardless of operating
mode.
The RSOP block provides descrambled data and frame alignment indication
signals for use by the Receive Line Overhead Processor.
9.3 Receive Line Overhead Processor
The Receive Line Overhead Processor block (RLOP) processes the line
overhead (multiplexer section) of a received SONET/SDH data stream. It can be
configured to process an STS-1, STS-3/STM-1, or STS-12/STM-4 data stream
PROPRIETARY AND CONFIDENTIALTO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE 32