lorawan: a solution for the
internet of things

The LoRaWAN network architecture is a star-of-stars one in which gateways act as transparent bridges that forward messages between end devices and a central network server in the backend.

The gateways are connected to the network server via standard IP connections, while the end devices use single-hop wireless communication over one or more gateways. End-point communication is generally bidirectional, but also supports operations such as multicast, allowing software updates over the air, or other mass distribution messages to reduce communication times.

Communication between end devices and gateway is spread between different frequency channels and data transmission speeds. The selection of data rate is a compromise between communication interval and message duration. Due to spread spectrum technology, communications with different data rates do not interfere with each other and create a series of "virtual" channels, increasing the capacity of the gateway. LoRaWAN data rates range from 0.3 kbps to 50 kbps. To maximize both end device battery life and overall network capacity, the LoRaWAN network server manages data rate and RF output for each end device individually via an Adaptive Data (ADR) scheme. Rate).

Protection is provided by several levels of encryption:

1) The unique network key (EUI64) ensures network level security.

2) The unique application key (EUI64) ensures end to end security at the application level.

3) Device specific key ( EUI128).

LoRaWAN has different classes of end-point devices:

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Bidirectional end devices (Class A): end devices Class Aenable bidirectional communications where each end device uplink transmission is followed by two short downlink receive windows.The transmission slot planned by the end device is based on its communication needs with a small variation based on a random time base (ALOHA protocol type).

Bidirectional end devices with programmed receive slots (Class B): in addition to windows Class A random reception, Class B devices open extra reception windows at predetermined times. The terminal device receives a synchronized synchronization signal from the gateway, to ensure that it opens the receive window at the scheduled time. This allows the server to be aware of when the terminal device is listening.

Bidirectional end devices with maximum reception slots (Class C): end devices of Class C have almost continuously open reception windows, which close only during transmission.