Extending the Mesh
Smart Mesh Part 7
One of the major driving forces of the smart mesh communication protocol is range. Range is limited and depends on the performance of the transmitter as well as the sensitivity of the receiver radio. The propagation of radio waves in the microwave spectrum is severely constrained by walls and other obstacles preventing direct communication between devices. Materials such as tree leaves or anything that contains lots of water such as concrete (ceilings) or bricks (walls) will highly absorb microwaves.
Broadcast and Relay
The new Bluetooth Smart Mesh improves communication by defining a protocol permitting an ad-hoc creation of a mesh network between devices. This is realized by allowing small packets of data to be transported from source to destination through a set of intermediary relay nodes. The Bluetooth SIG calls nodes, that are able to relay mesh packets, inner nodes. Those devices need external power and won't run on batteries for a long time. A relay node must listen for radio transmission all the time and transmit every packet that hasn't been seen yet and has not exhausted the relay count.
Wireless Cables Inc. is specialized in long range Bluetooth devices. We created products that extend the range of Bluetooth (10m normally) to hundreds of meters, even kilometers. The highest FCC certification is for our Host XR product at 10km range with certified directional 18dBi panel antennas.
Our products are able to do that because they have a very sensitive receiver based on low noise amplifiers that can coexist with high power microwave transmitters. This means that our products can hear the very faint signals (under -100dBm strength).
Introducing the AIRcable SuperBridge
We bring this technology to the smart mesh with the AIRcable SuperBridge. It is based on our proven long range radio design, being able to listen for smart mesh packets and transmitting them at a high output power. Because of its superior radio sensitivity and output power it is best smart mesh relay available. From an economical standpoint, only a very small number of those relays are required to bridge the range gap between mesh nodes. It is a standalone device and requires external power to operate.
One of the biggest advantages is maintenance: there is no maintenance. The functionality of the relay is independent of the number or type of nodes in the mesh. It is independent of the size of the mesh. Also the location within the mesh is irrelevant. It can just be deployed and automatically all submesh nets are connected.
Our product, though, is mesh key dependent. This means that only packets which are part of a particular mesh network with a certain network key are being relayed. This rules out that the device can be used to infiltrate a mesh network and make it vulnerable to hackers far away. The network key cannot be read out of the NVM memory, since it is stored encrypted. The same strong AES-256 encryption standard is used. A new network key be introduced, but that requires access to the device and renders the existing one unrecoverably lost.
Our current version also provides a GATT service for devices that cannot directly interact with the mesh. Some type of smart phones still have a restriction on how Bluetooth Low Energy packets are created and received. On iPhone, we can receive and decode all mesh packets, but the transmission of mesh packets are going through iBeacons. The SuperBridge converts those to mesh packets. On ChromeOS and Android Chrome DEV the Web Bluetooth API only allows GATT connections. The SuperBeacon implements the GATT Bearer protocol as well, but with added security. Only packets that are part of the mesh network and have the same network key are being relayed.
The AIRcable SuperBridge is really a super mesh relay. With this product large deployments of mesh networks with lots of nodes will be economical. For everyone who ever managed a larger number of Bluetooth sensor nodes in one location will find the maintenance free relays a time an money saver. Especially in outdoor locations, asset tracking with mesh nodes can now be economical.