RAK7249 8 Channel Redundancy

Hi,

I set up my RAK7249 16 channels with the same config/frequency for concentrator 1 & 2:

  • Concentrator 1 : 920.2, 920.4, 920.6, 920.8, 921, 921.4, 921.6, 921.8
  • Concentrator 2 : 920.2, 920.4, 920.6, 920.8, 921, 921.4, 921.6, 921.8

What happens during Tx, which concentrator will be used for TX? Does this disable the Rx of one concentrator when Tx on another concentrator?

Cheers,
Andri

1 Like

Dear Andri,

If you need to set up the same channel, it is not necessary to turn on both channels at the same time, as you are using two 8-channel gateways!

Hi @xflash,
First of all, could you explain why are you trying to use both concentrators with the same chanal frequency?
You can refer to this document: https://downloads.rakwireless.com/LoRa/DIY-Gateway-RAK7249/Application-Notes/Packet_Forwarder_Customs%20_Spectrum_Setting_KR920.pdf
but keep in mind that it’s about KR920 settings.

Hi @Nikola,

Sorry, late response. I want to check if this setup can be used for full duplex, one concentrator can still be listening (Rx) while at the same time another one is transmitting (Tx). But again, the antenna need to be separated in such a way that the transmission has less effect on the Rx path. So, is this setup possible or not?

As I don’t believe there’s any time coordination between the two concentrator cards, a downlink would essentially have to be transmitted by whichever one received the triggering uplink, which with a redundant setup it should be fairly random which got a better signal.

It’s unclear that you’ll be able to get enough antenna separation for meaningful receive performance during transmit. Typically the gatways that are actually full duplex work on bandplans where there is frequency separation between uplink and downlink, and use a very sharp physical filter called a diplexer - neither seems applicable to your situation.

Really you’d be better off with two basic 8-channel gateways spaced some distance apart.

I think so, for now, I just put two 8-channel gateways separated 1 km apart. Of course, I had to find a proper place for placing the gateway, which was very difficult especially in rural area. In the end, I had to put it on a rod (2-3 m) and attach it on top of utility pole. I wonder if there is a full-duplex lorawan gateway (uplink-downlink in separate frequency) available on the market.

First you’d have to determine if such a split in frequencies is even legal in your location, Given the uplink frequencies you list, my guess would be it is not.

Which LoRaWAN regional parameters are you using?

It’s AS923-2 (RP1.0.1): 920 MHz - 923 MHz

That doesn’t really leave room for segregating uplink vs downlink, and even if it did, that wouldn’t be the standard frequency plan.

I think so, but I heard the regulatory will open 433 MHz for LPWAN in this region (Indonesia). Still in long discussion…

@xflash,

Chris seems to have said it all I suppose. Although I think the US915 band is large enough for this to work there, for example with them having 64 channels.
He is also right about antenna diversity, you are better of with 2 gates, as to get a meaningful benefit from the two concentrators you would need to space them quite far apart, via the antennas, which would mean extension cables, additional attenuation introduced, etc. Simply too complicated in a way.

Regards
Vladislav

By the way our current firmware does not support concentrator modules from different bands for example AS923 and 433

Ok, Thanks for your info @Hobo :+1:t2: