Architecture LoRaWAN: exam questions with worked answers

Questions for the "Architecture" topic

1. Q01

   An important distinction must be made: "LoRa" is the physical-layer radio modulation (CSS, Chirp Spread Spectrum, proprietary to Semtech), whereas "LoRaWAN" is the MAC-layer protocol and network architecture (an open standard from the LoRa Alliance) built on top of LoRa.

   TrueFalse

   1. Architecture· LoRa vs LoRaWAN· Medium

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   Correct answer

   True

   Learning tip

   LoRa and LoRaWAN sit at different layers of the stack. LoRa is the Semtech-owned physical-layer technology based on Chirp Spread Spectrum modulation (the silicon-level IP is licensed only by Semtech and a handful of partners). LoRaWAN is the open MAC-layer protocol plus end-to-end network architecture defined by the LoRa Alliance. A useful analogy: LoRa is to LoRaWAN what raw Ethernet wiring is to TCP/IP — devices can use LoRa without LoRaWAN through proprietary protocols, but the standardised, interoperable ecosystem is LoRaWAN.

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2. Q02

   LoRaWAN uses a "star-of-stars" topology: each end device transmits unidirectionally toward ALL in-range gateways, the gateways forward the packet to the Network Server, which deduplicates the copies; there is no mesh between end devices.

   TrueFalse

   1. Architecture· Star-of-Stars-Topologie· Medium

   ▸

   Correct answer

   True

   Learning tip

   Each end device broadcasts its uplink without targeting any particular gateway. The Network Server then receives N copies through the N gateways that heard the frame, keeps the best one (typically the strongest RSSI/SNR) for downlink scheduling and drops the duplicates. The main benefit is intrinsic gateway redundancy and robustness, since adding a gateway only improves coverage without any device-side reconfiguration. The trade-off compared with mesh stacks like Thread, Zigbee or Z-Wave is that LoRaWAN end devices cannot communicate directly with each other — every message has to go up through the infrastructure.

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