USA & Canada Sub-Band Plan

(Chris Merck) #1

With the 72 uplink channels we have in the USA, and the limitation of current gateways to 8 channels, we have some frequency planning to do. The 72 uplink channels are divided into 8 sub-bands, each containing eight 125kHz wide channels and one 500kHz wide channel. The question is, as we deploy gateways (eventually blanketing metropolitan areas or even whole states), how do we want to assign gateways to sub-bands?

We could put all gateways on one sub-band (say #7). The principle advantage of the single sub-band plan is redundancy/localization: multiple adjacent gateways can pick up the same signal, providing redundancy in case of interference / loss, and allowing poor-man's localization using RSSI (and, eventually, localization via DToF ?).

Another plan would involve a "cellular" assignment of sub-bands, where adjacent gateways listen on distinct sub-bands. This makes better use of spectrum (unless you figure that more retransmissions may be required due to lack of redundancy).

My opinion is that we should stick to a single sub-band plan for USA until we hit capacity issues, and only then (re)assign gateways to a secondary sub-band.


Single Channel (Low Cost) Gateway
(Thomas Telkamp) #2


The plan is indeed to start with a common sub-band for North America. This will maximise coverage initially, and get the project off the ground. We do the same in EU with a single channel plan.

We probably should not be using sub-bands #1 and #8, as they might be used as default by other systems.

Do you have any insight in what a good choice would be? We have been using #7 a bit so far, but maybe something in the middle, like #4 or #5 is better?


How about sub-band #0 ?

(Chris Merck) #4

In USA the 915MHz band is shared with many services, so it's hard to predict what portions of the band will be less utilized.

LoRaWAN's frequency hopping should help avoid narrow-band interferers, but we are still vulnerable to wide-band interferers (such as 802.11ah). Using sub-band #0 would minimize interference from the wideband interferers because they do not operate so close to the band edge.


Sorry Chris - it was a trap. A facetious trap to flag the issue that sub-bands don't exist (officially).
In the thread above one post uses #1 to #8 and as I've seen elsewhere, I suggested #0 to #7.

We need to get the LoRa Alliance to include the concept of sub-bands in to the standard so that we can all agree on the numbering used, otherwise we'll run in to trouble between different vendors of nodes/gateways/servers.