Sept. 13, 2012

LDPCSPA (Low Density Parity Check - Sum Product Algorithm)

This code was used to obtain the results presented in: 

Lampoudi, S.; Brevik, J.; O'Sullivan, M.E.;  
"Combinatorial Properties as Predictors for the Performance of the 
Sum-Product Algorithm," 12th Canadian Workshop on Information Theory 
(CWIT), pp.134-138, 17-20 May 2011.

Authors: 	Rich Wolski (wolski@cs.ucsb.edu)
		Sotiria Lampoudi (slampoud@cs.ucsb.edu)

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Compiling the code: on a UNIX machine with a C compiler (we have tested with
gcc), and GNU make, edit the Makefile to match your compiler and type 'make'.

We have included an example matrix file (example_graph.g) to illustrate the 
matrix format. 
The matrix file is a simple text file. The first entry gives the number of 
checks (141 in our example); the second entry gives the number of bits (282
in our example). The subsequent entries each represent an edge between a 
a check and a bit, in check:bit format. The checks and bits are numbered
starting at zero (0). The entries are separated by a single space. 

For example, you could use the given matrix file like so:
./ldpcspa -g example_graph.g -s 4 -R 0.5 -F 1000 -Q 
where the signal-to-noise ratio is 4, the rate is 0.5, the decoder generates
1000 random frames, and the printing out of frames that failed to decode is 
suppressed (by -Q). 

Running the binary without arguments, like so:
./ldpcspa
will result in a message explaining the commandline options.

Please do not hesitate to contact slampoud@cs.ucsb.edu for clarifications.