I’m exploring LoRaWAN communication for remote monitoring of Off-grid Solar PV microgrids in Indian rural context (remote locations). Its an outdoor setting and moreover its a plateau region. I’ve the following questions, please help me with the same:
Node:
How do I decide between LoRa chip and LoRa module/shield, which one should I go with?
There is a wide range of LoRa shields/modules available out there (from different manufacturers). What should be the criteria/factors based on which I can decide a specific shield/module for my application?
Note: I’m using Arduino development board
Gateway:
Are there any authorized distributors in India from where we can source RAK 831 gateway module?
Can we use Raspberry Pi 3 to setup the LoRaWAN gateway using RAK 831 gateway module? Or can we use advanced versions also, like Pi 3B+, Pi4?
On that critreria there is not going to be any difference between shields or modules, all current modules for nodes are based on the same Semtech LoRa device the SX127x. There might be very small differences in power output between modules, but it will be marginal and unlikley to make a difference.
Note that the fitting on gain antennas for more distance, and this applies to Gateways too, will in a lot of places not be legal as you will exceed permitted power levels.
However some places do allow for more power than is common in Europe (14dBm) so its wortwhile checking the regulations for your part of the World.
Since I had two sets of questions, one for the node and the other for the gateway, I thought I’ll have to post them under two different categories.
Now that the posts are merged, can we add the category of Gateway as well, to this post? Is that possible? (Currently it’s showing only ‘End Devices’ category).
For development purpose, its not that important. But when we go for field deployment, I’m not sure if ethernet is available in the test site, in which case I’ll be left with choosing between cellular and wifi. Is it possible to have cellular communication based backhaul in LoRaWAN network?
I understand that the same chip is being used, but why is it then there’s wide cost difference between the lora shields of different manufacturers? For instance I’ve given three cases here, the cost difference can clearly be seen:
what range between node and gateway(s)
landscape / area
antenna height
are there other gateways in the area
how many nodes
are these nodes battery operated
how often do they transmit and what is the payload size, what do you measure
what is your budget, hobby (I think) or professional
did you find a local LoRa material supplier in INDIA ?
’ but why is it then there’s wide cost difference between the lora shields of different manufacturers? For instance I’ve given three cases here, the cost difference can clearly be seen:
that’s a strange question … why is A more expensive then B ??
did you calculate transport costs, for example from DE to IN ?
The RAK831 (and 833, etc) is not a gateway but merely the multichannel radio card to use in one. With care you should be able to create a better thermal design to passively remove heat (it consumes a lot of power in a small area!) and weather enclosure than almost any gateway on the market. On the other hand, building something up from parts is a lot more work.
There are few side-by-side comparison of range type performance of different manufacturer’s integration of the same Semtech ICs into gateway radio cards, but it is a subject to be curious about. In a situation where performance might be found disappointing, a key thing to check would be the power supply. Switching power supplies are more energy efficient (waste less heat) but inherently noisy and require careful filtering when used in radio applications. The RAK831 has its own switching regulator from 5v to 3v3; something like the RAK833 requires that you construct your own and provide it with 3v3. A not uncommon compromise can be to have a switching regulator or power supply which provides 5v to the gateway’s computer, and then use a linear regulator to reduce this (while quieting it in the process) to 3v3 for the radio card. With care, a switching regulator should be possible; but if issues with weak signal reception are seen, it would be a prime suspect.
You can certainly use a Raspberry Pi (really any variety of it) to build a temporary gateway. However, the dependence on an SD card makes it far, far less robust for a field installation than the types of embedded computers typically and best used in deployable gateways (even when operated in a “read only” mode a modern consumer SD card is not truly read only, but conducts its own behind-the-scene refreshing of data) Most true embedded computers instead uses an eMMC chip, or better yet NAND flash or best of all run from a ramdisk initialized from a compressed image stored on an SPI NOR flash. But if (or as long as) your application can tolerate being down until you physically go to the gateway and replace the card with a prepared spare, a pi could be fine for initial efforts.
Incidentally, on the subject of cooling, more recently purchased RAK833’s have had a heatsink pad between the SX1301 chip and the shield lid, while initially purchased ones did not. Ended up popping the shield off of ours and adding one to those that did not have it; have not yet checked inside our single RAK831 example. We then use more thin pads to transfer heat from the shield to the aluminum mounting plate or chassis. We typically do the same thing with the computer board’s SoC. Many gateway “kits” unfortunately hide these heat generating parts inside where they don’t have any good path to shed the heat to the exterior.
I got my wimod-im880b shield for arduino. I want the arduino+wimod end node to get connected to TTN and send data. Searched for resources in TTN forum, but could not get any. Did I oversee? Please hep me out.
Very valid questions BoRRoZ. Though I’ve identified the application precisely, its very difficult to answer these questions because we’re just prototyping our solution. These questions will definitely help us to design our solutions. Thanks once again.
and help you where possible.