VSC6134
Datasheet
2.8.3
2.8.4
Deinterleaving Buffer
The deinterleaving buffer performs the 16× byte-deinterleaving of the 255-symbol Reed Solomon
encoded codewords carried within each FEC frame. After being deinterleaved, the codewords are
passed to the Reed Solomon decoder block according to ITU-T G.709 and G.975 recommendations.
Reed Solomon Decoder
The Reed Solomon decoder block operates on one FEC frame at a time (4080 bytes). The following
figure shows the main functional sub-blocks and signal flow implemented in the RS decoder. The block
is designed for high-performance applications and is configured for code block length of 255 8-bit
symbols with parity length of 16 8-bit symbols. It is capable of processing continuous 10-Gb data
streams in real time. The syndrome polynomial coefficients, the codeword length, and the parity length
are preset to meet ITU-T G.975 and G.709 recommendations.
Figure 21. RS Decoder Block Diagram
Key
Syndrome
Calculation
Equation
Solver
Polynomial
Evaluation
Forney
Calculation
Input
Register
Codeword FIFO
Syndrome Calculation
This block calculates the set of N-K syndromes associated with an input codeword.
Key Equation Calculation
The Syndrome polynomials are used to compute the N-K order error location polynomial and (N-K)-1
order error evaluation polynomial.
Polynomial Evaluation
This block accepts the output data from the key equation block and pre-processes the data for the Forney
search.
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VMDS-10185 Revision 4.0
July 2006
VITESSE [ VITESSE SEMICONDUCTOR CORPORATION ]
