LoRa protocol in space

As a bit of an addendum do this, LoRa is incredibly bandwidth inefficient. This is due to the use of the wide bandwidth chirp modulation (spreading).

As an example Fossasat-1 uses 125 kHz bandwidth, a ‘spreading factor’ of 11, and r=1/2 FEC to achieve a user data rate of… 335 bits per second. In doing so, any other station trying to operate within that 125 kHz bandwidth has the potential to be interfered with.
This approach works fine within an ISM band, and is probably a good (though ‘selfish’ - it only benefits the LoRa user) approach for dealing with co-channel interference.

However, in the amateur satellite band, we have a lot of satellites ‘competing’ for spectrum, and it sure would be nice if they interfered with each other as little as possible. Coordination is a part of this, but responsible use of spectrum is another important aspect.

The same data rate could be achieved with similar (probably better!) decode performance in a much narrower bandwidth just by using a narrow-band BPSK modulation. This could probably be achieved using something like a AX5043 chipset.
Examples of this working practice are sats like the Funcube series (Funcube-1, UKube-1, JYSAT), running 1k2 BPSK, and even the AO-40 BPSK beacon format (which has been around for a long time now).

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