New SensorMesh™ Gateway Box

We have a new SensorMesh™ Gateway Box that takes mesh data from a USB COM port and sends it to your server, BeaconServer™ or BeaconRTLS™.

It reads data from a COM port and uploads it to a server defined by a URL in the box’s web UI:

The web UI also shows the latest data received and the response from the server

Use of the Gateway Box is optional. We also have a Windows 10 service should you wish to do a similar thing on your PC/server or you can process the COM port data yourself for a more bespoke solution.

Read more about SensorMesh™

Survey of Mesh Technologies

There’s useful new research on Wireless Mesh Networking: An IoT-Oriented Perspective Survey on Relevant Technologies by Antonio Cilfone, Luca Davoli, Laura Belli and Gianluigi Ferrari of University of Parma, Italy. It covers how various communication technologies are suitable for mesh networking.

The paper explains mesh topologies and routing protocols. It describes Bluetooth:

“BLE is presently raising more and more attention and is becoming one of the leading technologies for both IoT-oriented and industrial scenarios”

The authors provide an in-depth introduction to SIG Bluetooth Mesh. (Note that an excellent higher level overview also very recently became available from InsightSIP). The research paper also mentions other Bluetooth mesh implementations such as the draft IETF Bluetooth Mesh for IPv6.

Applications such as smart city, industrial monitoring and smart agriculture are considered and factors such as interoperability and security are mentioned. Finally, the paper compares other protocols such as Thread, ZigBee and LoRaWAN.

Read about Beacons and the Bluetooth Mesh

Bluetooth Mesh for Industrial IoT (IIoT)

There’s an informative video presentation on the Bluetooth SIG web site on Simplifying Multi-Vendor Mesh and Sensor Networks. It provides an introduction to Bluetooth mesh and explains the ways in which it can provide for Industrial IoT (IIoT).

To add to this, Bluetooth Mesh is suitable for use on the factory floor where the environment can be electrically noisy. Standard Bluetooth Mesh uses advertising on several channels rather than (GATT) connections so as to provide for more reliable communication in environments with wireless interference.

Read about Beacons in Industry and the 4th Industrial Revolution (4IR)
Read about Beacons and the Bluetooth Mesh

RTLS Locating Using Mesh

You-Wei Lin and Chi-Yi Lin of Department of Computer Science and Information Engineering, Tamkang University, New Taipei City 25137, Taiwan have a paper An Interactive Real-Time Locating System Based on Bluetooth Low-Energy Beacon Network.

Although the implementation is similar to SensorMesh™ and BeaconRTLS™ used together, their solution uses a proprietary mesh implementation and a proprietary data protocol. Consequently, their implementation suffers longer response time when used over longer physical distances. Their maximum inter-hop distance of 8 to 10 m also isn’t good due to non-optimal devices and non-optimal device positioning.

Bluetooth Mesh, Thread and Zigbee Network Performance

Silicon Labs have a useful web site, webinar and slides on “Benchmarking Bluetooth Mesh, Thread, and Zigbee Network Performance”.

The two main measures of performance are throughput, the rate data transfer that can be achieved (in bits per second) and latency, the time taken for data to cross the network.

With a typical implementation of 6+ hops, throughput converges to a similar order of magnitude for all the protocols:

In real use these protocols only support of the order of low thousands of bits (not bytes!) per sec and should therefore only be used for sending small amounts of data that don’t change very often.

For a small payload with 192 nodes, Zigbee has lowest latency and Bluetooth has greatest variation of latency of 20ms to 200ms:

For a larger payload, the Bluetooth latency has a larger range of up to 750ms:

Whether the variation of latency matters depends on your particular solution. Which technology is best depends on what you need to accomplish. For example, in a Bluetooth lighting scenario you might not want some lights to come on immediately and far ones to come on up to a second later. For sensing, the delay usually doesn’t matter.

You also need to consider other factors such as interoperability, scalability, security, reliability and ease of deployment. For example, Zigbee is less scalable and Silicon Labs recommends a maximum of seven hops otherwise the network becomes congested due to re-tries. Bluetooth has especially good interoperability because it is ubiquitous on smartphones and other devices. It also works reliably in industrial situations and has double encryption.

All protocols can be difficult to deploy due to the lack of off-the-shelf general solutions outside specific verticals such as lighting and home automation although our SensorMesh™ is a notable exception.

Silicon Labs have a more specific paper on Bluetooth Mesh Network Performance.

Read about Beacons and the Bluetooth Mesh

Bluetooth Mesh Energy Consumption

There’s a new paper by Seyed Mahdi Darroudi, Raül Caldera-Sànchez and Carles Gomez of Department of Network Engineering, Universitat Politècnica de Catalunya/Fundació, Spain on Bluetooth Mesh Energy Consumption: A Model.

They set up some experiments to measure current consumption under various parameters:

They found that a sensor device running on a simple 235 mAh battery, sending a data message every 10 secs, can achieve a lifetime of up to 15.6 months.

This battery is probably a CR2032 battery. Read our post on Beacon Battery Size, Type, Capacity and Life for typical beacons battery sizes and capacities.

Read about Beacons and the Bluetooth Mesh

Read about SensorMesh™

Bluetooth Mesh Standard Evaluation

There’s recent new research on The Bluetooth Mesh Standard: An Overview and Experimental Evaluation (pdf) by Mathias Baert, Jen Rossey, Adnan Shahid ID and Jeroen Hoebeke of Ghent University.

The paper explains how the Bluetooth Mesh Standard came about to address the problem of the variety of BLE meshing solutions that were not interoperable. It includes a great introduction to Bluetooth LE and Mesh with some statistical and experimental insights into mesh performance.

The authors explain how the choice of the use of advertising advertising at 100% duty cycle for lower end-to-end delay has degraded the low energy advantage of BLE advertising thus limiting the usefulness in power (battery) sensitive applications.

The paper contains some useful insights:

  • The back off mechanism, used to decrease the chance of mesh network collisions, contributes most to the communication delay. However, as they identify, it’s this mechanism that provides reliability and scalability in larger networks. Disabling the backoff mechanism decreases the delay but makes the network less scaleable and robust.
  • Making the network more dense, has a positive effect on the round trip time (RTT). However too a dense network leads to more collisions.
  • Increasing the number of hops needed, making the network more sparse, has a negative effect on the RTT.

“It is clear that there are a lot of factors influencing the communication flows within a Bluetooth Mesh network, requiring more advanced management mechanism for optimizing the performance of the mesh network.”

However, the research had some limitations. Noise was simulated by introducing non-mesh beacons advertising every 20ms. This wasn’t very realistic given that most beacons advertise in the range 100ms to 1000ms. Re-transmit time was considered that complicated calculations – especially as re-transmit is application specific. It wasn’t mentioned that in many mesh sensing applications, unacknowledged messages are acceptable such that there’s no re-transmit. Also, the affect of other mesh network traffic, on the round trip time, wasn’t considered – only one mesh transmission at a time was considered.

Read about Beacons and the Bluetooth Mesh

Read about SensorMesh™

Latest Nordic WirelessQ Magazine Available

Beacons are small computers with a complete System on a Chip (SoC). There are four main companies that manufacturer SoCs: TI, Dialog, NXP and Nordic. Nordic is the most popular SoC for use in beacons, mainly because of the lower (tool) license cost and ease for beacon manufacturers developing the software (actually called firmware) that runs in the beacons.

Nordic has a new free Wireless Quarter Magazine that showcases uses of Nordic SoCs in many types of device, not just beacons.

Learn about:

  • Gartner research showing sensor innovation fosters IoT growth
  • Beacons help U.S. shoppers find way
  • Bluetooth LE in Amazon FreeRTOS
  • Bluetooth LE smart textiles on the rise
  • Article combining Bluetooth Low Energy and LPWANs
  • Firmwave’s use of Bluetooth Low Energy beacons to build an inexpensive satellite broadcast system
  • Article on Getting started with Bluetooth mesh

Read more