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LoRa & LoRaWAN DISCUSSION
I want to collect readings from four soil-moisture nodes spread over a farm, up to about 2 km from the house, and show them on a local dashboard. I have RFM95 modules. Some guides use plain LoRa between two modules, others set up a LoRaWAN gateway and register devices on a network server.
What is the actual difference between LoRa and LoRaWAN, and which approach makes sense for a small private setup like this?
LoRa is only the radio modulation: chirp spread spectrum as implemented in Semtech transceivers such as the SX1276 inside the RFM95. It defines how bits become chirps and nothing about addresses, acknowledgements or security. LoRaWAN is a network protocol built on top of it and maintained by the LoRa Alliance. It defines device addressing, join procedures, AES-128 encryption and integrity checks, frame counters, channel plans per region, data-rate control and the timing of downlinks.
With plain LoRa you design those pieces yourself. With LoRaWAN you follow the standard and get interoperable devices, gateways and servers.
A LoRaWAN network is a star of stars. End devices do not talk to each other or to one particular gateway; they transmit, every gateway in range forwards the frame over IP to the network server, and the server removes duplicates, checks the integrity code and passes the payload to your application. Downlinks go the other way, and a Class A device listens only in two short receive windows after each of its own uplinks, by default 1 s and 2 s after the transmission ends.
A real gateway uses a multi-channel concentrator that listens on eight channels and all spreading factors at once. A single RFM95 acting as a single-channel gateway is not compliant and breaks features such as channel hopping and adaptive data rate.
For four nodes and one receiver, plain LoRa is perfectly reasonable and much less to set up: one RFM95 with a microcontroller at the house as the receiver, connected to the dashboard computer over USB or Wi-Fi. All radios must share frequency, spreading factor, bandwidth, coding rate and sync word.
You need to add the missing protocol parts yourself: a node ID and a sequence counter in each packet, an integrity check or better an authenticated encryption of the payload, and random jitter on the transmit time so that nodes with the same period do not collide repeatedly. A 12-byte packet every 15 minutes from four nodes leaves the channel almost empty, so simple unacknowledged sends work well.
LoRaWAN is worth the effort when the system may grow, when you want commercial sensors to join the same network, or when the site already has coverage from a public or community network, in which case you need no gateway at all. A fully private setup is also possible: an eight-channel gateway plus a self-hosted open-source network server on a small computer, with nothing leaving your premises.
Whichever you choose, the radio rules are the same: stay within the regional limits for power and duty cycle, and test the link at the real antenna heights. At 2 km the deciding factor is usually line of sight, so mounting the house antenna high and outdoors matters more than the protocol.
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