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

Mimo
====

 It splits a stream into two sub-streams, and sends each sub-stream encoded
with a repetition-code (spreading) over a different antenna. On the receiver
side, each antenna filters the corresponding sub-stream and puts them
together.


Overview
--------

The signal-flow is as follows:

      /- spreading - Ant_tx_1 \       / Ant_rx_1 - despreading -\
Data <                         Channel                           >- sink
      \- spreading - Ant_tx_2 /       \ Ant_rx_2 - despreading -/

 In the channel, both sending antennas get mixed together to form the signal
at each reception antenna. So,

  Ant_rx_1 = h11 * Ant_tx_1 + h12 * Ant_tx_2
and
  Ant_rx_2 = h21 * Ant_tx_1 + h22 * Ant_tx_2

 In this very simple example, the spreading-factor (the length of the repetition
code) is chosen very big (8), so that no advantage from the MIMO can be taken.