Single Channel Packet Forwarder .... or not?

Hi all

I have play with the IoT for some time and now I will try the LoRaWAN.
I can see that there are no lora gateway in my city.
Then I think I will build a gateway, so I and many other in my city can connect and use that gateway.
But I see that the multi channel modules are very expensive (200 $), so I think I will buy a
Lora/GPS HAT module (33 $) and connect to my Rasberry Pi 2 for building a single channel gateway
for me and my city.
Is it a waste of time just to install a single channel gateway, or will it be OK ??

How does it look around ? Are the most gateway’s in Europe in multi channels ?

Best Regards Peder Bue

You could use a single channel gateway for your personal use/testing but I wouldn’t go as far as expecting “many others” (or others at all!) to use it.

It just doesn’t scale and while you may be aware of its limitations and special setup necessary others won’t understand why their nodes aren’t working as expected

I recommend a read of Thomas’s post on the topic Single Channel Gateway part 1

Well, you probably won’t be able to hook up the entire city to TTN using just one gateway anyway - unless it’s a very small city. Of course, for personal experimentation anything you can get to work will do just fine.

Note that the total costs of your suggested gateway aren’t as low as you suggest: a PI sets you back say 30 credits, but that’s just a very barebone PI. You’ll need some kind of housing, a power supply (PoE?), probably additional memory, cabling, perhaps a SD card, shield, antenna… all in all you might be better off buying a 250 credit ready-to-run TTN gateway + antenna. A decent gateway, based on a PI, will set you back roughly 500 credits (or so I’m told).

Gateways I’m currently building are:

RisingHF concentrator board $160
Adapter board: $10
NanoPi NEO: $8
SD card: $5
Antenna: $7
Case: $5
Power supply: $10

Total US$205 - add a bit of shipping here and there and total cost is about $230

These are single unit prices, I actually got it for less by buying a larger quantity.

If you can add GSM capabilities + robust ip67 enclosure. I’ll buy a few :smiley:

I’m using the well known StationBox ALU as a IP66 rated enclosure, it does add about $50 to the price for parts and extra shipping costs.

Do you really need IP67 i.e. full immersion protection? I think this is a very solid, very well made case.

GSM capabilities? Interesting, what would you use them for? Internet connectivity? I’m very interested in any options that might provide fall-back to GSM if the regular host Internet line dies.

Yeah, IP67 would be perfect for us. We are planning to install it in outdoor remote hill sites in Scotland. The extreme weather does warrant IP67 protection.
GSM due to lack of broadband. But surprisingly you can get 3g coverage when you are 1km above sea level :smiley:

Thanks for all the answers.

I understand the limit on a single channel gateway.
I am maybe the first one that will playing with Lorawan in my city, because I can not see any gateway
in the city.
I have allready two Rasberry Pi2 with PSU,sdcard … and many arduino that all are ready for my next projekts
so I think a good cheap plan to start with, will be to buy a Lora Shield for a Rasberry Pi for the gateway and a Lora Shield for arduino to make one lorawan node. Then I can start playing and learn howto work with lorawan.
Maybe after some time, other people are connecting to my gateway and the gateway will very soon reaches its limit, I
can buy a multichannel card for the gateway and use the old Lora shield just for one more Node.
I can see that there are a new cheaper GW platform on way. Look like the SX1308 is half price of SX1301.
So maybe there are a SX1308 rasberry Pi board ready, when I after some months need this multichannel solution.

Not the perfect start, but a cheaper start.

Have I overlooked some important facts here ?

When I rmake the gateway registration on the first gateway, is it possible to make a note, that this is “only” a single channel gateway ?

Peder Bue

So, the GSM would be the primary communciation channel to use for contacting the backbone, right? I’m in the Northern parts of the Netherlands in the rural parts, smack in the middle of nowhere - I can appreciate your quest for (very) watertight housing :smile:

@fortean Yep that’s right. GSM would be the primary communication channel. We are planning to cover a wide area with strategically placed renewables powered gateways running on the TTN for rural applications of LoRaWAN.

@peder Sorry for hijacking your post :slight_smile:

@peder - a gateway is a gateway, in as far as I know. I have not heard of any “comments fields” you can provide, but see on how to connect a gateway. I’ve noticed that a list of channels / frequencies is available on my gateway, but I’m merely hosting it. Perhaps @kersing can chime in and help you.

ETA: from the TTN FAQ,

    What is the difference between a "single-channel gateway" and a "real gateway"?

    A real gateway is able to listen on 8 channels and all spreading
    factors at the same time. Single-channel gateways are fixed to one
    channel and spreading factor, so they will only receive about 2% of the
    messages unless you specifically configure your nodes to send at the
    exact same configuration as your single-channel gateway.

    As LoRaWAN is a spread-spectrum radio protocol, single-channel
    gateways are not LoRaWAN-compatible. They can only be used for plain
    LoRa (without WAN) communication or for testing, and are not supported
    by The Things Network

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    I see there is a BIG different between an single and multiply channel gateways.

    I just need to send some bytes from a node a few times per day. If somebody has a single
    channel gateway 24/7 in my town, I will just use this and not build my own.
    If it was possible to make one registration for a normal gateway and another registration for a “limit” single channel gateway, it will help more people to startup playing with lora devices that not need to much data extraction.

    Maybe that’s why 75% of gateways in Denmark are unclaimed !

    Peder Bue

    The amount of data is not the issue. Single channel gateways do not adhere to the standard where gateways must listen to multiple frequencies with different speeds. As nodes choose the frequency for a transmission at random from the ones listed in the standard a lot of transmissions will not be received by a single channel gateway.

    A minor aside: Jaap Braam’s single channel gateway listens to all spreading factors (and supports OTAA and downlinks too).

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    But is still not LoRaWAN specification compliant. However it is the best choice if you really want to go for a single channel gateway. The esp8266 should beat the price of a raspberry pi as well.

    What would be the biggest advantage building gateways this way? For a couple of bucks more, you’d have a full TTN gateway that’s ready out of the box right? I am trying to figure out if it’s better to wait a little longer and buy the TTN gateway, or build one myself.

    Ok, Thanks for the info :slight_smile:

    As I remember from my radio amateur days, working with AX25 packet radio. There are lot of
    stations tramsmite and receive on the same frekvens. There are handshake, so the transmitter need a
    ok from the receiver, otherwise it will transmite it again. It working perfect with many stations and no data
    get missed…

    So if the lorawan GW are set with a fixed frekvens, and the Nodes on the same, it must have a handshake in the protocol to control this.
    But lorawan are maybe not design for this way to work, so it will not be the same as the AX25 protocol packet radio :slight_smile:

    LoRaWAN is not designed this way. The idea, for the Class A nodes to send and forget. With the various SF and frequencies, there is little chance all messages will not be received. The node can use few ACKed messages to ensure the communication exist and is reliable.

    Nothing prevent to use LoRa (without WAN) technology to benefit from long range low power communication, but a different stack need to be used. RadioHead is one of the various library you can use. It will implement the mechanism to ensure a reliable communication in point to point LoRa modulation using single frequency.

    When the DIY gateway option appeared, the GW cost was more in the 500-1200 range. Now some have more hobbyist price point.

    With the DIY approach, we’ve been able to play, at a reasonable cost, for a year, without going bankrupt :slight_smile:.

    The initial target was July 2016, but some delay has been experienced. I hope we will have soon our gateways delivered.

    Make or wait is up to you and depend of the urgency of your project.

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