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88 lines
3.2 KiB
HTML
88 lines
3.2 KiB
HTML
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<HTML><HEAD>
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<TITLE> Examples of LDPC Program Usage </TITLE>
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</HEAD><BODY>
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<H1> Examples of LDPC Program Usage </H1>
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<P>Below, are some command files containing examples of the use of
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the <A HREF="progs.html">LDPC programs</A>, together with the output I
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obtained for these examples. Output on other machines might
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conceivably be slightly different, due to different round-off errors.
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The <A HREF="run-examples"><TT>run-examples</TT></A> script runs all the example
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scripts and compares their output with the outputs that I obtained (on
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a Pentium machine).
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<P><A HREF="ex-ham7b">ex-ham7b</A>,
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output in <A HREF="ex-ham7b-out">ex-ham7b-out</A>
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<BLOCKQUOTE>
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A (7,4) Hamming code used with a BSC.
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Demonstrates encoding of random messages and decoding to minimize
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bit error rate by exhaustive enumeration.
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</BLOCKQUOTE>
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<P><A HREF="ex-ham7a">ex-ham7a</A>,
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output in <A HREF="ex-ham7a-out">ex-ham7a-out</A>
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<BLOCKQUOTE>
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A (7,4) Hamming code used with an AWGN channel. Tested using zero messages.
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Decoded by exhaustive enumeration to minimize either block or bit error rate,
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and by probability propagation.
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</BLOCKQUOTE>
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<P><A HREF="ex-dep">ex-dep</A>,
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output in <A HREF="ex-dep-out">ex-dep-out</A>
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<BLOCKQUOTE>
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Examples of how parity check matrices with linearly dependent rows (ie,
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redundant parity checks) are handled. This is probably not of
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great interest to most users.
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</BLOCKQUOTE>
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<P><A HREF="ex-ldpc-encode">ex-ldpc-encode</A>,
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output in <A HREF="ex-ldpc-encode-out">ex-ldpc-encode-out</A>
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<BLOCKQUOTE>
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Encodes messages with an LDPC code using sparse, dense, and mixed
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representations of the generator matrix.
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</BLOCKQUOTE>
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<P><A HREF="ex-ldpc36-1000a">ex-ldpc36-1000a</A>,
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output in <A HREF="ex-ldpc36-1000a-out">ex-ldpc36-1000a-out</A>
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<BLOCKQUOTE>
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A (2000,1000) LDPC code with 3 checks per bit and 6 bits per check.
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Three encoding methods are tried out, and the code is
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tested on an AWGN channel at various noise levels, using random messages.
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</BLOCKQUOTE>
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<P><A HREF="ex-ldpc36-5000a">ex-ldpc36-5000a</A>,
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output in <A HREF="ex-ldpc36-5000a-out">ex-ldpc36-5000a-out</A>
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<BLOCKQUOTE>
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A (10000,5000) LDPC code with 3 checks per bit and 6 bits per check.
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Tested on an AWGN channel at various noise levels, using random messages.
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Pipes are used to avoid creating lots of files.
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</BLOCKQUOTE>
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<P><A HREF="ex-ldpcvar-5000a">ex-ldpcvar-5000a</A>,
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output in <A HREF="ex-ldpcvar-5000a-out">ex-ldpcvar-5000a-out</A>
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<BLOCKQUOTE>
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A (10000,5000) LDPC code with the number of checks per bit varying from 2 to 7.
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Tested on an AWGN channel at various noise levels, using random messages.
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Pipes are used to avoid creating lots of files. Performance is better than
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for the code above in which the number of checks is the same for all bits.
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</BLOCKQUOTE>
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<P><A HREF="ex-wrong-model">ex-wrong-model</A>,
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output in <A HREF="ex-wrong-model-out">ex-wrong-model-out</A>
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<BLOCKQUOTE>
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Tests what happens when messages are decoded using the wrong noise
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model, including using the right type of model but with the wrong
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noise level, and using the wrong type of model (ie, using an AWLN model
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for messages transmitted through an AWGN channel, or vice versa).
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</BLOCKQUOTE>
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<HR>
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<A HREF="index.html">Back to index for LDPC software</A>
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