RE Mote networking
The RE-Mote automatically creates a self-healing wireless mesh network, addressable over IPv6 on top of 6LoWPAN. This allows to connect to traditional IP-based networks over TCP/UDP, like other WiFi or Ethernet connected device would do, consuming from 60-300 times less power than any WiFi device.
One benefit of being an IPv6 capable device is to be able to use protocols such as CoAP, LWM2M and MQTT, the very protocols nowadays used for most Internet of Things Cloud-based applications. IPv6 addresses gives devices a global unique address, allowing to use pings to check if your device is online, run a webserver on the RE-Mote and read data from any web browser, and more.
The mesh extends the range by allowing devices to help each other by relaying each other’s messages. This also ensures reliability as if one known route disappears, a given RE-Mote can find a new route and heal the network, no need to manually configure static routes.
When a message is sent in a mesh network, it travels through a number of hops (the number of nodes between the intended receiver and origin) to reach its destination. With the RE-Mote and its on-board long range radio you can easily cover distances of kilometres in this fashion, although by itself in a single hop it can reach from 100 meters to 5-10 kilometres (depending on the wireless settings).
To achieve a long lifetime, radios are switched off as much as possible. But when the radio is switched off, the node is not able to send or receive any messages. The nodes in the network save energy by duty cycling the radios, powering off and on, when not sending any data (with the radio off up to 99% of the time)
Keeping the radio on ensures reception of messages normally in a single attempt, this is a common trade-off with sleepy devices, as normally if a node is to communicate with other node, then it has to repeat the same message in a period in which the receiver is known to be awaken, for the data to be received. If both devices are known they can synchronize themselves to know the approximate moment in which the neighbours are likely to be awaken, and reduce the number of retransmission required. Tuning also the radio duty cycle also reduces the attempts required to communicate, depending on your needs this is something to play with.
MQTT and CoAP support communication from Internet-based resource-rich devices to IoT-based resource-constrained devices. Both implement a lightweight application layer, and work nicely with the RE-Mote. The differences arises on the underlying protocols: MQTT runs on top of TCP (connection oriented) while CoAP uses UDP (connection-less), both with its own pros and cons.
The RE-Mote supports UDP, TCP, HTTP, MQTT, CoAP and LWM2M. This is of great importance as it allows to interact and communicate with other compliant devices (regardless the technology), Internet of Things Cloud based platforms and applications.
Read more about this in the following links:
- 6LoWPAN demystified, written by Texas Instruments
- Why a Mesh?, by our partners at Thingsquare
- More info about MQTT
- More info about CoAP