Add EU_433 frequency plan

[htdvisser]

Summary

This adds the EU 433 frequency plan

Closes #17

The min/max frequencies in the the sub-band and radio come from the Regional Parameters 1.0.2 specification:

652 EU433 end-devices should be capable of operating in the 433.05 to 434.79 MHz frequency
653 band

Then we start with the channels:

649 The LoRaWAN channels center frequency can be in the following range:
650 * Minimum frequency : 433.175 MHz
651 * Maximum frequency : 434.665 MHz
...
656 The first three channels correspond to 433.175, 433.375 and 433.575 MHz with DR0 to DR5

And after that, we just continue with the same spacing.

I've placed the 250kHz channel at 434.075 MHz, since we've seen some 250kHz uplinks at that frequency in the past, so there seem to be some gateways out there that listen on this frequency.

I've configured the radios to listen at the center of the 4 channels they're responsible for.

I've taken the chip-type: SX1255 and rssi-offset: -176 from the CN470 plan, since I assume that EU433 uses the same chip.

Checklist

• [x] Scope: The referenced issue is addressed, there are no unrelated changes.
• [x] Compatibility: The changes are backwards compatible, they don't break existing deployments.
• [ ] Testing: The changes are tested.
• [ ] Documentation: Relevant documentation is added or updated.

[jpmeijers]

As a reference, this extract from the South African regulations for the 433MHz bands for Non-specific SRDs insluding RFID.

Relevant Standards

• EN 300 220 - Short Range Devices (SRD) operating in the frequency range 25 MHz to 1 000 MHz (part1, part2)
• EN 301 489-1,3 - ElectroMagnetic Compatibility (EMC) standard for radio equipment and services (part1, part3)
• EN 60950 - Information technology equipment - Safety

Additional Requirements

• CEPT/ERC/REC 70-03 - ERC Recommendation relating to the use of Short Range Devices (SRD)

The only subband we can use is G1 which is 10mW at <10% duty cycle. G2 can't be used as our bandwith is 125kHz or 250kHz, which is not greater than 250kHz. G3 can't be used as our bandwith is not less than or equal to 25kHz.

Amateur radio

The amateur radio band overlaps the ISM band

IARU Region 1 band plan

i.Channels with centre frequencies 432.500, 432.525, 432.550, 432.575, 434.450, 434.475, 434.500, 434.525, 434.550 and 434.575 may be used for digital communications. n. Common frequencies for Simplex (FM) Internet voice gateways are: 433.950, 433.9625, 433.975, 433.9875, 434.0125, 434.025, 434.0375, 434.050 MHz (Cavtat 2008)

TODO: Consider the location of the LoRaSTB 255kHz channel, as it overlaps with experimental amateur radio digital communication. Or is this maybe a good thing?

RFID channels

On the EU868 LoRaWAN frequency plan the LoRa channels were chosen to fall between RFID channels, to minimise interference between the two band users. We need to get a list of common EU433 RFID channels to try and do the same thing.

According to ERC70-03, Annex 11: Radio Frequency Identification Applications (see Additional Requirements above), there are no RFID channels assigned in the 433MHz band.

Medical application

See ERC70-03, Annex 13: Medical Data Acquisition. There is a band assigned 430-440MHz for Ultra-Low Power Wireless Medical Capsule Endoscopy. Users should therefore be aware not to use LoRaWAN EU433 in and around a medical theatre where endoscopy is performed, as it can cause interference. Also see EN 303 520.

[jpmeijers]

Personal comment:

• I think your suggestion looks fine.
• It would be nice to have an amateur radio operator (in NL, maybe @pe1mew Remko) comment on the 250kHz LoRaWAN channel.
• I don't see the point of using 433MHz for LoRa as the output power is limited to 10mW in Erope (vs 25mW on 868MHz). In South Africa the situation is different as there is a 100mW assignment, but I still won't recommend using it, as it's not following the ITU recommendations, and therefore can be dropped at any point.

[pe1mew]

I looked into it from a radio-amateur perspective and looked up IARU band plan for this frequency from here: https://www.iaru-r1.org/wp-content/uploads/2021/03/UHF-Bandplan.pdf

433 MHz ISM band is shared on a non-interference basis where some interference between users shall be accepted. Current detail planning is visualised in the following table:

Frequency [MHz] start-stop	channel bandwidth [kHz]	use
433.000-433.375	12	FM/DV Repeater RX (downlink) for 25kHz raster, +1.6MHz shift.
433.400-433.575	12	FM/DV Simplex 25kHz raster, 433.400 MHz SSTV (FM/AFSK), 433.450 MHz DV callfrequency, 433.500 MHz mobile callfreq.
433.600-434.000	20	433.600 MHz RTTY (FM/AFSK), 433.625-433.775 MHz DV channels, 433.700 MHZ FAX (FM/AFSK), 434.000 MHz digital experiments CoA
434.000-434.594	12	ATV, alle mode Digital channels
434.594-434.981	12	Repeater TX (uplink) regio 1 standaard (25kHz raster, 1.6MHz shift

• From practical experience and from measurements by Dutch regulator (for example) it is learned that the 433 ISM band is rarely used by radio amateurs and interference is likely to be neglected.
• Special care shall be taken with the usage of 433 ISM frequencies in the UK because their FM repeaters are using 433.000-433.375 for downlink. These signals will disturb channel performance seriously.

[johanstokking]

@jpmeijers @pe1mew thanks for looking into this as well.

@pe1mew do you suggest any changes to the proposal here?

[pe1mew]

@pe1mew do you suggest any changes to the proposal here?

I have no reason to suggest changes. In my opinion, all relevant sources have been queried and regulation allows this usage. It is good to be aware of other users of these frequencies.

In line with the nature of frequency sharing, as in this case, I would like to suggest the use of ADR to automatically minimize the use of frequencies that suffer from interference by other users. It is good to know that as a user of these frequencies with secondary status, measures should be in place to minimize the interference of users with primary status on these frequencies.