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ldpc_2fold
==========


 LDPC codes are Low Density Parity Check codes used in favor of
convolutional codes. Usually they are calculated on a SISO channel.
This module tries to enhance the case for a 2x2 MIMO channel. The
theory has been written down by Nicolae Chiurtu.


ldpc_decode_2fold
-----------------

LDPC-decoder using the 2fold-techinque to decode a stream coming from a
MIMO environment.

Inputs:
	SYMBOL_COMPLEX[2]

outputs:
	U8

Config:
	chest1<int>: -1
		Block-id of the ChEst1 block. This will provide variance and h11 and h12.

	chest2<int>: -1
		Block-id of the ChEst2 block. This will provide variance and h21 and h22.

	iterations<int>: 30
		The total iteration-number. For each iteration, iterations_left
		followed by iterations_right are done.

	iterations_left<int>: 1
		How many iterations to the left are done per total iteration

	iterations_right<int>: 1
		How many iterations to the right are done per total iteration

	ldpc_code_id<int>: 1
		The number of 
		The index of the ldpc-code. For the moment, three codes
		are implemented:
		1 - rate .25, size 4000
		2 - rate .5, size 3992
		3 - rate .75, size 3992


Stats:
	snr<double>:
		The calculated SNR in case of a AWGN channel


ldpc_encode_2fold
-----------------

 Encodes a slot. Needs to have a modulator-module with a QPSK
modulation.

Inputs:
	U8

outputs:
	U8

Config:
	ldpc_code_id<int>: 1
		The index of the ldpc-code. For the moment, three codes
		are implemented:
		1 - rate .25, size 4000
		2 - rate .5, size 3992
		3 - rate .75, size 3992