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Hi,
In line 151 of the code,
"preamble_legacy_B = [circshift(sts_t_rep, [0, TX_SPATIAL_STREAM_SHIFT]), zeros(1, 160)];"
Could you advise why does the sts_t_rep need to be shifted here? What happen if I dont use the shift?
Thanks.
Regards,
whardj
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That cyclic shift helps prevent unintentional beamfoming. When two antennas transmit the same waveform, the two waveforms will interfere as they propagate. At any given point in space the received waveform will be either a constructive or destructive combination of these waveforms. The cyclic shift here de-correlates the waveforms to avoid destructive combinations at potential receivers. This is the same technique used in the 802.11n/ac standards when transmitting the legacy preamble on multiple antennas.
Also- the new MIMO OFDM example is built for WARPLab 7.6, which will be posted soon. The signal processing in this example can be used with other WARPLab versions (or other M code applications), but the WARPLab-specific code assumes WL7.6.
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One quick correction: wl_example_mimo_ofdm_txrx.m SVN revision 4676 still supports WARPLab 7.5.1. However, the latest SVN version (which is the link in the wiki page) will soon only support WARPLab 7.6.
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