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Worksheet Intro to GRS Decoding

We will use Sugiyamaโ€™s algorithm to decode GRS codes. This algorithm uses a modification of the extended Euclidean algorithm to solve the key equation for the ELP and EEP.
Letโ€™s practice using Sugiyamaโ€™s algorithm for GRS decoding. For the following problems, we will work with the \([8,4,5]_{13}\) GRS code over \(\F_{13}\) with code locators \(\balpha=(1,4,3,12,9,10,5,8)\) and column multipliers \(\bv=(12,11,2,1,2,11,11,2)\text{.}\) This code has canonical parity check matrix given by
\begin{equation*} H_{\GRS}=\begin{bmatrix} 12 \amp 11 \amp 2 \amp 1 \amp 2 \amp 11 \amp 11 \amp 2 \\ 12 \amp 5 \amp 6 \amp 12 \amp 5 \amp 6 \amp 3 \amp 3 \\ 12 \amp 7 \amp 5 \amp 1 \amp 6 \amp 8 \amp 2 \amp 11 \\ 12 \amp 2 \amp 2 \amp 12 \amp 2 \amp 2 \amp 10 \amp 10 \end{bmatrix}\text{.} \end{equation*}

1.

Suppose the vector \(\by=(0,0,0,0,0,0,3,5) \) is received. Step through Sugiyamaโ€™s algorithm to find an error vector \(\be\) and decoded codeword \(\bc\text{.}\) You should be able to determine these answers without doing any work at this point in the semester - use this example to solidify your understanding of the process.

2.

Now suppose the vector \(\by=(3,6,0,4,0,5,0,12) \) is received. Step through Sugiyamaโ€™s algorithm to find an error vector \(\be\) and decoded codeword \(\bc\text{.}\)