# Single Channel Packet Forwarder .... or not? **URL:** \ **Category:** \[obsolete\] SCPF\ **Created:** [January 6, 2017, 10:12pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698 "2017-01-06T22:12:37Z")\ **Posts on this page:** 19\ **Page:** 2
**Author:** ![jmarcelino](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/jmarcelino/32/46753_2.png) [@jmarcelino](https://www.thethingsnetwork.org/forum/u/jmarcelino)\ **Post date:** [January 9, 2017, 10:18am UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/21 "2017-01-09T10:18:36Z")
> [@rolandow](#): > > What would be the biggest advantage building gateways this way? Well one is availability, I’ve had gateways like this since October, but also customisation. For example I can plug in a $10 3G USB dongle and have a 3G ready gateway very quickly, I can add Power over Ethernet or a watchdog circuit using the same methods people have been doing on Raspberry Pis and the like for ages. Also being Linux based its very easy to configure remote access via SSH/VPN or use something like [Resin.io](http://Resin.io) for configuration management. Of course if you don’t need any of this, only want a gateway you can plug in at your home or office then the TTN gateway should be just what you need. ---
**Author:** ![peder](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/peder/32/31908_2.png) [@peder](https://www.thethingsnetwork.org/forum/u/peder)\ **Post date:** [January 9, 2017, 11:02am UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/22 "2017-01-09T11:02:00Z")
Yes, I think it will be the best for me, to just do the LoRa without the WAN and use it to receive my data from my node far away. I will keep an eye on prices and opportunities to build a real gateway at a later time. Thanks for all the good answers. Great with this communities, to share knowledge. ---
**Author:** ![adilhidayat](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/adilhidayat/32/3781_2.png) [@adilhidayat](https://www.thethingsnetwork.org/forum/u/adilhidayat)\ **Post date:** [February 22, 2017, 1:10pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/23 "2017-02-22T13:10:14Z")
> [@kersing](#): > > es choose the frequency for a transmiss @kersing Is it a valid question for me to ask **_how many nodes can a single channel gateway handle?_** ---
**Author:** ![BoRRoZ](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/borroz/32/44234_2.png) [@BoRRoZ](https://www.thethingsnetwork.org/forum/u/BoRRoZ)\ **Post date:** [February 22, 2017, 1:17pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/24 "2017-02-22T13:17:05Z")
10000… but only one at a time 😉 _so if you have for example 6 nodes in your house, and they all point to the same frequency, that will work off course, but the gateway will miss a message if several nodes start transmitting at the same time (collision) a real gateway will not miss these packets, up to 8 simultaniously on all frequencies and SF’s._ ---
**Author:** ![arjanvanb](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/arjanvanb/32/46626_2.png) [@arjanvanb](https://www.thethingsnetwork.org/forum/u/arjanvanb)\ **Post date:** [February 22, 2017, 7:21pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/25 "2017-02-22T19:21:34Z")
> [@BoRRoZ](#): > > the gateway will miss a message if several nodes start transmitting at the same time (collision) a real gateway will not miss these packets, up to 8 simultaniously on all frequencies and SF’s. …but only one per combination of frequency and spreading factor, right? In other words: a full gateway will also **not** be able to decode 8 messages if they collide (that is: if they use the same frequency and the same SF at the same time). At best, a gateway will then be able to decode one of the messages. If nodes use different frequencies (channels) or the same frequency but different spreading factors (sub-channels), then a true gateway can indeed receive multiple messages. ---
**Author:** ![BoRRoZ](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/borroz/32/44234_2.png) [@BoRRoZ](https://www.thethingsnetwork.org/forum/u/BoRRoZ)\ **Post date:** [February 22, 2017, 7:22pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/26 "2017-02-22T19:22:29Z")
nailed it 🕶 ---
**Author:** ![douglarue](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/douglarue/32/25844_2.png) [@douglarue](https://www.thethingsnetwork.org/forum/u/douglarue)\ **Post date:** [February 22, 2017, 9:49pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/27 "2017-02-22T21:49:53Z")
One of the single channel gateways with ListenBeforeTalk capabilities will give you multiple spread factor capabilities. ---
**Author:** ![arjanvanb](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/arjanvanb/32/46626_2.png) [@arjanvanb](https://www.thethingsnetwork.org/forum/u/arjanvanb)\ **Post date:** [February 23, 2017, 6:23am UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/28 "2017-02-23T06:23:53Z")
Indeed, some single channel gateways can _detect_ a signal on all SFs of a single channel. But once detected, unlike full gateways, they can only decode one at a time. Also, the mechanism these single channel gateways use for that limit their range: [https://github.com/JaapBraam/LoRaWanGateway#how-multiple-spreading-factors-are-detected](https://github.com/JaapBraam/LoRaWanGateway#how-multiple-spreading-factors-are-detected) As an aside: I think you’re confusing Channel Activity Detecting (CAD) with Listen Before Talk (LBT). No single channel gateway I know does LBT, and given the tightly defined receive windows in LoRaWAN, I think no full gateway can use LBT either. They simply need to send when the time has come, regardless if anyone else is sending too. ---
**Author:** ![pe1mew](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/pe1mew/32/48520_2.png) [@pe1mew](https://www.thethingsnetwork.org/forum/u/pe1mew)\ **Post date:** [February 23, 2017, 7:19am UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/29 "2017-02-23T07:19:18Z")
> [@arjanvanb](#): > > I think no full gateway can use LBT either. They simply need to send when the time has come, regardless if anyone else is sending too. As lora is capeable of having multiple transmissions at the same time I do not expect this to be a big issue. Also the fact that up and downlink are kind of a “different path” helps. ---
**Author:** ![douglarue](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/douglarue/32/25844_2.png) [@douglarue](https://www.thethingsnetwork.org/forum/u/douglarue)\ **Post date:** [February 23, 2017, 3:16pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/30 "2017-02-23T15:16:38Z")
Yes, I had confused LBT with CAD. Thanks. ---
**Author:** ![arjanvanb](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/arjanvanb/32/46626_2.png) [@arjanvanb](https://www.thethingsnetwork.org/forum/u/arjanvanb)\ **Post date:** [February 23, 2017, 5:32pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/31 "2017-02-23T17:32:19Z")
> [@pe1mew](#): > > As lora is capeable of having multiple transmissions at the same time But not on the same frequency and SF. (Of course, multiple nodes can send on the same frequency and SF, but a gateway will receive at most one.) > [@pe1mew](#): > > Also the fact that up and downlink are kind of a “different path” helps. Not sure what you mean, and probably a different topic: gateways are half-duplex. So if a gateway transmits, it cannot listen at all ☹ That’s one of the reasons why downlinks are so “expensive” for the network. ---
**Author:** ![kersing](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/kersing/32/44777_2.png) [@kersing](https://www.thethingsnetwork.org/forum/u/kersing)\ **Post date:** [February 23, 2017, 7:15pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/32 "2017-02-23T19:15:11Z")
> [@pe1mew](#): > > As lora is capeable of having multiple transmissions at the same time I do not expect this to be a big issue. Also the fact that up and downlink are kind of a “different path” helps. Full LoRaWAN gateways are able to _receive_ multiple transmissions, not transmit multiple streams at the same time. Also as a gateway has one antenna which is switched from the receivers to the transmitter while transmitting the gateway can’t receive while transmitting. ---
**Author:** ![kersing](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/kersing/32/44777_2.png) [@kersing](https://www.thethingsnetwork.org/forum/u/kersing)\ **Post date:** [February 23, 2017, 7:20pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/33 "2017-02-23T19:20:41Z")
> [@arjanvanb](#): > > I think no full gateway can use LBT either. The newer Lora gateway code base suggests Semtech fpga based gateways might be able to. ---
**Author:** ![arjanvanb](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/arjanvanb/32/46626_2.png) [@arjanvanb](https://www.thethingsnetwork.org/forum/u/arjanvanb)\ **Post date:** [February 23, 2017, 7:23pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/34 "2017-02-23T19:23:53Z")
> [@kersing](#): > > The newer Lora gateway code base suggests Semtech fpga based gateways might be able to. But then only for broadcasting, right? Given the defined receive windows, a gateway could tell some backend that RX1 is busy, but for RX2 it has no other choice than just send. (Or keep silent and discard the packet.) ---
**Author:** ![kersing](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/kersing/32/44777_2.png) [@kersing](https://www.thethingsnetwork.org/forum/u/kersing)\ **Post date:** [February 23, 2017, 7:51pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/35 "2017-02-23T19:51:06Z")
> [@arjanvanb](#): > > but for RX2 it has no other choice than just send No, if local regulations do not allow transmission when another device is sending the only right choice is to discard the packet and tell the back-end it was not sent. ---
**Author:** ![manvendra98](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/manvendra98/32/20484_2.png) [@manvendra98](https://www.thethingsnetwork.org/forum/u/manvendra98)\ **Post date:** [June 10, 2019, 5:05pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/38 "2019-06-10T17:05:08Z")
I am following this blog and i am taking away that my one channel gateway LG-01 dragino will not be able to communicate with the nodes of different SFs. Am i right? Please correct if i am wrong. 🙂 Can you give insights on how to do it also? Thank you :)) ---
**Author:** ![UdLoRa](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/udlora/32/45330_2.png) [@UdLoRa](https://www.thethingsnetwork.org/forum/u/UdLoRa)\ **Post date:** [June 10, 2019, 7:14pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/39 "2019-06-10T19:14:03Z")
You are right. How to do: buy a real gateway 🙂 . The The Things Indoor Gateway costs little more than a LG-01. ---
**Author:** ![manvendra98](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/manvendra98/32/20484_2.png) [@manvendra98](https://www.thethingsnetwork.org/forum/u/manvendra98)\ **Post date:** [June 11, 2019, 12:06pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/40 "2019-06-11T12:06:01Z")
Thank you so much. 🙂 Sure, I will look into that. ---
**Author:** ![bluejedi](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/bluejedi/32/44639_2.png) [@bluejedi](https://www.thethingsnetwork.org/forum/u/bluejedi)\ **Post date:** [July 8, 2021, 10:15pm UTC](https://www.thethingsnetwork.org/forum/t/single-channel-packet-forwarder-or-not/4698/41 "2021-07-08T22:15:54Z")
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