What are linear codes having minimum distance 2 used for?












0












$begingroup$


Consider the following parity check matrix



$$H = begin{bmatrix}
1 & 0 & 1 & 1 & 1 & 1 \
0 & 1 & 1 & 0 & 0 & 1 \
1 & 1 & 0 & 1 & 0 & 1
end{bmatrix}$$



Since its 1st and 4th column both are identical, the minimum distance of a code is 2. If we compute the syndrome of any received vector $vec{r}$ and it comes out to be zero, we can't possibly tell whether the received vector is correct or not (as 1st and 4th bit of $vec{r}$ could be incorrect).



If we can't verify whether the received vector is correct or not, what are linear codes having minimum distance used for?










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  • $begingroup$
    Really no matter what distance your code has, you can't possible tell whether the received vector is correct or not if there is more than 1 code word (in a distance $d$ code, you could potentially have $d$ errors). So what are you really asking here?
    $endgroup$
    – Morgan Rodgers
    Dec 8 '18 at 3:42
















0












$begingroup$


Consider the following parity check matrix



$$H = begin{bmatrix}
1 & 0 & 1 & 1 & 1 & 1 \
0 & 1 & 1 & 0 & 0 & 1 \
1 & 1 & 0 & 1 & 0 & 1
end{bmatrix}$$



Since its 1st and 4th column both are identical, the minimum distance of a code is 2. If we compute the syndrome of any received vector $vec{r}$ and it comes out to be zero, we can't possibly tell whether the received vector is correct or not (as 1st and 4th bit of $vec{r}$ could be incorrect).



If we can't verify whether the received vector is correct or not, what are linear codes having minimum distance used for?










share|cite|improve this question











$endgroup$












  • $begingroup$
    Really no matter what distance your code has, you can't possible tell whether the received vector is correct or not if there is more than 1 code word (in a distance $d$ code, you could potentially have $d$ errors). So what are you really asking here?
    $endgroup$
    – Morgan Rodgers
    Dec 8 '18 at 3:42














0












0








0





$begingroup$


Consider the following parity check matrix



$$H = begin{bmatrix}
1 & 0 & 1 & 1 & 1 & 1 \
0 & 1 & 1 & 0 & 0 & 1 \
1 & 1 & 0 & 1 & 0 & 1
end{bmatrix}$$



Since its 1st and 4th column both are identical, the minimum distance of a code is 2. If we compute the syndrome of any received vector $vec{r}$ and it comes out to be zero, we can't possibly tell whether the received vector is correct or not (as 1st and 4th bit of $vec{r}$ could be incorrect).



If we can't verify whether the received vector is correct or not, what are linear codes having minimum distance used for?










share|cite|improve this question











$endgroup$




Consider the following parity check matrix



$$H = begin{bmatrix}
1 & 0 & 1 & 1 & 1 & 1 \
0 & 1 & 1 & 0 & 0 & 1 \
1 & 1 & 0 & 1 & 0 & 1
end{bmatrix}$$



Since its 1st and 4th column both are identical, the minimum distance of a code is 2. If we compute the syndrome of any received vector $vec{r}$ and it comes out to be zero, we can't possibly tell whether the received vector is correct or not (as 1st and 4th bit of $vec{r}$ could be incorrect).



If we can't verify whether the received vector is correct or not, what are linear codes having minimum distance used for?







linear-algebra matrices coding-theory parity






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edited Dec 6 '18 at 1:27







Heisenberg

















asked Dec 5 '18 at 23:51









HeisenbergHeisenberg

1183




1183












  • $begingroup$
    Really no matter what distance your code has, you can't possible tell whether the received vector is correct or not if there is more than 1 code word (in a distance $d$ code, you could potentially have $d$ errors). So what are you really asking here?
    $endgroup$
    – Morgan Rodgers
    Dec 8 '18 at 3:42


















  • $begingroup$
    Really no matter what distance your code has, you can't possible tell whether the received vector is correct or not if there is more than 1 code word (in a distance $d$ code, you could potentially have $d$ errors). So what are you really asking here?
    $endgroup$
    – Morgan Rodgers
    Dec 8 '18 at 3:42
















$begingroup$
Really no matter what distance your code has, you can't possible tell whether the received vector is correct or not if there is more than 1 code word (in a distance $d$ code, you could potentially have $d$ errors). So what are you really asking here?
$endgroup$
– Morgan Rodgers
Dec 8 '18 at 3:42




$begingroup$
Really no matter what distance your code has, you can't possible tell whether the received vector is correct or not if there is more than 1 code word (in a distance $d$ code, you could potentially have $d$ errors). So what are you really asking here?
$endgroup$
– Morgan Rodgers
Dec 8 '18 at 3:42










2 Answers
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$begingroup$

If the minimum distance is $d=2t+1$ with $tgeq 1$, then the code can correct $t$ errors. The minimum value for $d$ is 3. A code with minimum distance 2 can only detect one error but not correct it.






share|cite|improve this answer









$endgroup$





















    0












    $begingroup$

    The typical (practically, the only) linear code with minimum distance 2 is the single parity code which consist of adding a single parity bit, hence $n=k+1$. It detects a single error. See some uses in the page above.



    Given that your code is $(6,3)$, it looks rather bad, because for $k=3$ you could have the single parity $(4,3)$ with better rate and same minimum distance. It's true that minimum distance is not the only parameter to judge the quality of the code (more important is the probability of erroneous decoding), but it looks bad anyway.






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      2 Answers
      2






      active

      oldest

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      2 Answers
      2






      active

      oldest

      votes









      active

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      active

      oldest

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      2












      $begingroup$

      If the minimum distance is $d=2t+1$ with $tgeq 1$, then the code can correct $t$ errors. The minimum value for $d$ is 3. A code with minimum distance 2 can only detect one error but not correct it.






      share|cite|improve this answer









      $endgroup$


















        2












        $begingroup$

        If the minimum distance is $d=2t+1$ with $tgeq 1$, then the code can correct $t$ errors. The minimum value for $d$ is 3. A code with minimum distance 2 can only detect one error but not correct it.






        share|cite|improve this answer









        $endgroup$
















          2












          2








          2





          $begingroup$

          If the minimum distance is $d=2t+1$ with $tgeq 1$, then the code can correct $t$ errors. The minimum value for $d$ is 3. A code with minimum distance 2 can only detect one error but not correct it.






          share|cite|improve this answer









          $endgroup$



          If the minimum distance is $d=2t+1$ with $tgeq 1$, then the code can correct $t$ errors. The minimum value for $d$ is 3. A code with minimum distance 2 can only detect one error but not correct it.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Dec 6 '18 at 6:42









          WuestenfuxWuestenfux

          4,2531413




          4,2531413























              0












              $begingroup$

              The typical (practically, the only) linear code with minimum distance 2 is the single parity code which consist of adding a single parity bit, hence $n=k+1$. It detects a single error. See some uses in the page above.



              Given that your code is $(6,3)$, it looks rather bad, because for $k=3$ you could have the single parity $(4,3)$ with better rate and same minimum distance. It's true that minimum distance is not the only parameter to judge the quality of the code (more important is the probability of erroneous decoding), but it looks bad anyway.






              share|cite|improve this answer









              $endgroup$


















                0












                $begingroup$

                The typical (practically, the only) linear code with minimum distance 2 is the single parity code which consist of adding a single parity bit, hence $n=k+1$. It detects a single error. See some uses in the page above.



                Given that your code is $(6,3)$, it looks rather bad, because for $k=3$ you could have the single parity $(4,3)$ with better rate and same minimum distance. It's true that minimum distance is not the only parameter to judge the quality of the code (more important is the probability of erroneous decoding), but it looks bad anyway.






                share|cite|improve this answer









                $endgroup$
















                  0












                  0








                  0





                  $begingroup$

                  The typical (practically, the only) linear code with minimum distance 2 is the single parity code which consist of adding a single parity bit, hence $n=k+1$. It detects a single error. See some uses in the page above.



                  Given that your code is $(6,3)$, it looks rather bad, because for $k=3$ you could have the single parity $(4,3)$ with better rate and same minimum distance. It's true that minimum distance is not the only parameter to judge the quality of the code (more important is the probability of erroneous decoding), but it looks bad anyway.






                  share|cite|improve this answer









                  $endgroup$



                  The typical (practically, the only) linear code with minimum distance 2 is the single parity code which consist of adding a single parity bit, hence $n=k+1$. It detects a single error. See some uses in the page above.



                  Given that your code is $(6,3)$, it looks rather bad, because for $k=3$ you could have the single parity $(4,3)$ with better rate and same minimum distance. It's true that minimum distance is not the only parameter to judge the quality of the code (more important is the probability of erroneous decoding), but it looks bad anyway.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Dec 8 '18 at 3:37









                  leonbloyleonbloy

                  40.6k645107




                  40.6k645107






























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