I am trying to get to the bottom of what is permitted and legal (and safe) in the UK when it comes to LoRaWAN gateways and their transmit power. I see many indoor gateways quoting 14dBm (25mW) and outdoor gateways at 27dBM (500mW). But looking further there are plenty of indoor gateways with 27dBM too!
Simply. Is it safe to use indoors a LoRaWAN gateway which quotes 27dBm?
I am looking for an “official” document that specifies what is and is not permitted (in the UK) and what is and isn’t considered safe!
Can anyone help? It seems to be a complicated and somewhat grey area to me so far!
In the UK TTN Gateways occupy the segment that permits 14dBm.
The limit does vary around the World, so in some places you can use more power. Thus its not unusual to see Gateways advertising with more power than you can legally use (in the UK).
If you think about it there is little point in using a gateway that has more transmit power than what the nodes can use …
No that is not what Stuart said! The limit in UK is 14dBm…power can be lower than capability - manufacturers built higher capabiities as that is what can be used elsewhere. Your local settings will (should !) limit to 14dBm for UK/EU
Also be carefull to allow for the ‘gain’ (dBi) of any antenna used if not running with a nominal 2(.15)db ant if you are not allowing for losses through a long cable run…higher power at the GW can be used to compensate for any losses…
Ok, part of my confusion is that it looks like MultiTech have changed their datasets between feb and now for various of the EU gateways. In feb that said variously 23.6dBm and 27dBm, They now say 14dBm.
So even though you might buy a gateway (in the UK) that says 27dBm, you are saying that by default (in software) it will be set to 14dBm?
Hi @patmolloy, there’s 2 “official documents” that you should study for the EU/UK.
The EU CEPT/ECC is the legal document that defines the RF bands, the permitted power levels, the channel access, etc. I believe that the latest document is:
The LoRa Alliance; LoRaWAN Regional Parameters. This is not a legal document but contains the definitions of the channel plan for regional interoperability. The EU863-870 RF band, a.k.a. EU868 is in use in the UK. I believe that the latest document is:
Sorry. I am probably not being precise enough with my language … Let’s take the TTIG (TT Indoor Gateway) which for the people it’s aimed at is simply plug and play, with (as far as I know) limited scope for easy changes to configuration. The datasheet says …
This costs $69. For the person who installs this (in the UK, for example) I wonder how they know what they are actually getting? It goes *up to +27bBm" but there is literally nothing in the setup process that allows you to dial that back to 14dBm.
Without access to a spectrum analyzer (or similar) I wonder how one is able to figure out whether this is really at +27dBm or +14dBm or something else?
But I take your general point that whatever the datasheet says it’s up to you to make sure it’s compliant!
I have looked at IR2030 (Page 23) and also the frequency plan for EU863-870 …
The short summary is that there is one of the frequencies (869.525 MHz) that Gateways can use to transmit Downlink messages (RX2) where it is permissible to go to 27bBm on this frequency. The other frequencies are all 14dBm.
It is always 14dBm for nodes transmitting on all of the frequencies.
Frequency plan for LoRaWAN is United Kingdom (UK) EU863-870
EU863-870
Uplink: (i.e. LoRaWAN node transmitting to a gateway)
868.1 - SF7BW125 to SF12BW125
868.3 - SF7BW125 to SF12BW125 and SF7BW250
868.5 - SF7BW125 to SF12BW125
867.1 - SF7BW125 to SF12BW125
867.3 - SF7BW125 to SF12BW125
867.5 - SF7BW125 to SF12BW125
867.7 - SF7BW125 to SF12BW125
867.9 - SF7BW125 to SF12BW125
868.8 - FSK
Downlink: (i.e. a LoRaWAN gatetway transmitting to a node)
The Downlink frequency of 869.525MHz does fall within the frequencies highlighted in yellow above (i.e. 869.40 – 869.65MHz) and the Maximum Transmit Power is defined as 500mW e.r.p (or 27dBm).
Dont forget LoRaWAN has 2 x dowlink windows as noted above - the 1st and most used (for Class A use cases per TTN) - is the RX1 Window at 1Sec after Node uplink…this is at same frequency and hence same dBm & duty cycle limit as the node i.e. 14dBm in UK. If Rx1 fails then Rx2 window 2 seconds after at the fixed frequency & with option for higher Tx pwr/higher duty cycle is used…
This is independant of GW type (indoor vs outdoor) or placement (again indoor or outdoor) … office workshop I’m running testing both classes in both types of deployment - though the normally indoor located GW’s have additional casing/protection when using for outdoor or sheltered external deployments.
Thanks. Yes to the two RX windows. We are definitely seeing some downlinks in RX2. And I think that this is what has triggered the 27dBm on that frequency seen on a spectrum analyser and triggering an alarm bell with someone who was under the impression we should never see anything over 14dBm.
