[Ronja] Multiple receivers and transmitters

[CD930]

MIMO and FSO?  ehm...  noooo.
This is only for RF with COFDM and guard interval pilots.

Martin

  ----- Original Message ----- 
  From: PRAMOD YADUVANSHI 
  To: Twibright Ronja 
  Sent: Saturday, September 20, 2008 8:25 PM
  Subject: Re: [Ronja] Multiple receivers and transmitters


  I feel for a laser based link MIMO will be a better option to improve SNR but for LED based Tx/Rx scintillation effects will be almost negligible and MIMO will hardly help. 


  2008/9/20 Gregory Maxwell <gmaxwell na gmail.com>

    On Sat, Sep 20, 2008 at 1:09 PM, J.D. Bakker <jdb na lartmaker.nl> wrote:
    >>I have been thinking how to divide multiple heads between receivers
    >>and transmitters optimally, i. e. if we want to build N heads, how
    >>to get the maximum range.
    >
    > Given N transmitters and M receivers, it might be better (but more
    > complicated) to apply MIMO techniques.



    In radio the problem that MMIO solves is multipath: Between your TX
    and RX  there are obstructions which alter the signal, they shift
    phase in a frequency dependent manner, and creates nulls and peaks.
    MMIO uses spatially separated antenna which get different views of the
    multi-path environment.  You can then define a collection of filters
    which take advantage of the multipath to form separate channels and
    gain capacity.

    For a fairly slowly amplitude modulated optical path like RONJA I
    would not expect there to be significant multipath. I do not believe
    MMIO would help.  But MMIO systems typically use efficient modulation
    systems  which would probably help ronja very much, but supporting
    them would be very costly.

    Karel where does the noise come from in the receive head are we
    talking about optical background noise which would increase with
    increased collection area or is it primarily noise from the
    photodetector and amplifier?   If it is primary electronic noise,
    creating a larger passive collector may allow you to increase receiver
    area without seeing much of a nosie increase.

    So long as your transmitter area is strictly smaller than the
    reciever's field of view, however, you would always be as well or
    better off to increase the transmitter area.  though perhaps you may
    wish to make the receiver more selective (for example, by placing it
    at the back of a long black tube).


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