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This a framework to test new ideas in transmission technology. Actual development is a LDPC-coder in

biterror
========

A simple channel simulation which can be used in a test
Simply inverts some bits with a predefined probability



block
=====

After the modules work with a very simple chain, it is nice to have a
next step before using the channel-simulator. The 'block' goes between
'rrc' and 'matched_filter' and simulates a perfect channel with the
appropriate attenuation. A future todo could be to add some noise.
 As most of the normal chains don't set the IO-size, you can do so
using the 'size'-config



block_4by4_complex
==================

This block is used for simulations of the channel. It implements
a NxM MIMO-system, where N and M are <= 4.
 One can give the size of the block in samples as well as the
precision of the A/D converter.
 The channel-matrix h[n][m] represents the channel between the
tx-antenna (input) 'm' and the rx-antenna (output) 'n'.
 For the receiving-antenna you can give the sigma of the white noise.
Please be aware that the sigma is between -32767 and 32767, and compares
to a signal-amplitude set by the modules (usually around 10000), whereas
the more conventional sigma compares to a signal-amplitude of 1.



block_complex
=============

This module gives a general 2x2 MIMO block with definable
channel-matrix h and noise-variance sigma.
 Additionally to the size, a precision in bits can be given,
too. This precision is used to cut off the transmitted signal,
which simulates a perfect channel, but with some error due to the
A/D converters.



block_mimo
==========

This block simulates the channel interface between two transmitting
antennas with two receivers. This block also adds noise.
The block implements the following,
 y = Hx + n



loop
====

Some of the subsystem has been faulty (and some still is, I'm sure), so
this loop-block is there to test some of it's functionality. Internally,
it copies the input_n to output_n and you can set the IO-size using the
'size' parameter.