Beacon Signal Stability Observations

As previously mentioned, we perform signal strength and stability tests across beacons. The data feeds into our consultancy work. Here are some high level observations.

The following graph shows the standard deviation of the RSSI @ 1m, for some of our beacons, measured over a 60 second time period:

beaconsignalstability

Smaller bars are better and represent beacons
whose RSSI varied the least over time.

We found that beacons belonged to one or two groups. Firstly those with very stable RSSI and secondly those with an RSSI that had a standard deviation between about 4 and 6 dBm.

Signal stability is more important when you are using the RSSI to infer distance, either directly from the RSSI itself or indirectly via, for example, the iOS immediate, near and far indicators. RSSI varying without a change of distance might cause more spurious triggering. However, you should keep in mind that environmental factors can often cause variation much larger than the 4 to 6 dBm found in this test. Moving obstacles, for example people, will cause significant variation in RSSI.

Bluetooth LE advertising moves pseudo-randomly between radio channels. The channels use different radio frequencies that, in turn, results in fading of the signal at different distances. We experienced and mitigated similar behaviour in our BluetoothLocationEngine™. Different radio frequencies experience different constructive and destructive interference at different physical locations. Beacons that move more between channels can cause more rapidly varying received signal strength (RSSI).

Using iBeacon for Team Management

There’s useful research by Sindhumol S of Cochin University of Science and Technology, India on Implementation and Analysis of a Smart Team Management System using iOS Devices as iBeacon.

The system provides location-based task monitoring and presence detection. Task details and announcements are available when a team member enters the range of an iBeacon broadcast. The system also provides typical project management facilities such as task allocation, notification, instant chat, status reports and employee logs.

From a technical perspective, the paper describes setting the beacon measure power, the affect of distance change on accuracy and the change in accuracy/RSSI depending on obstacle blocking.

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Which Beacons Support iBeacon and Eddystone Simultaneously?

Beacons periodically transmit a small amount of standard Bluetooth data. The format of that data varies depending on whether it’s iBeacon, Eddystone and sensor data.

Beacon advertising protocols

We sometimes get asked which beacons support advertising of multiple protocols simultaneously. The ‘simultaneous’ category on the web store shows beacons that can be set to advertise more than one protocol.

Note that, in actual fact, no beacon can send multiple protocols simultaneously. Instead the advertising data is sent for a protocol, very shortly, milliseconds, after the other.

Adding an IoT Protocol to Beacons

There’s new research by Department Computer Science, Universidad Técnica de Machala, Ecuador on Design and Practical Evaluation of a Family of Lightweight Protocols for Heterogeneous Sensing through BLE Beacons in IoT Telemetry Applications.

The researchers explain how standard beacon advertising works and documents the existing iBeacon and Eddystone protocols.

New protocols, LP4S-6 (for resource-constraint beacons), LP4S-X (for more powerful beacons) and LP4S-J (for beacons able to run complex firmware) are proposed that can be used to allow IoT telemetry systems to discover new nodes and to describe and auto-register the sensors and actuators connected to a beacon.

The paper describes the resultant JSON, shows how a new protocol can be added to an Eddystone beacon and proves how the new latency and power consumption remain low.

Note that updating the firmware of a beacon is non-trivial because it requires the implementation of what’s already on the beacon without access to the original source code.

How Many Connections Can an iBeacon Support?

We sometimes get asked how many connections an iBeacon can support? The answer is ‘1’ but it’s often the right answer to the wrong intended question. The intended question is usually “How many receivers can see a beacon?”

Beacons don’t usually connect. They just advertise and can be seen by an infinite number of receivers that include phones, gateways or single board computers such as the Raspberry Pi.

The receivers only usually connect once, during setup via an app, to set the initial iBeacon parameters. When connected, the beacon doesn’t advertise which prevents extra receivers from connecting. Once set up, the app disconnects and the beacon starts advertising again.

Next Generation Sign-In Technology Using iBeacons

Our customer, Ostara Systems, have added Bluetooth beacons to their Maintenance Management Solution. Beacons allow engineers to automatically sign-in and prove that they are working on site.

Beacons provide a significant improvement in the sign in process, reducing administration and providing for a quicker and easier sign in using the Ostara app. 1300 Bluetooth Beacons have been installed that are used by over 10,000 engineers.

Contact Ostara regarding their Facilities Management Solution

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Unexpected Beacon Solutions

Occasionally, our customers ask for things we didn’t expect, contradictory requirements or requests that require unusual solutions. Here are some examples:

  • We were once asked for the beacons we considered to be least attractive. The idea was that they were going to be rolled out into a busy public space and would otherwise easily get spotted and stolen. Small, black beacons turned out to be the solution.
  • We have been asked for beacons that last the longest time. While, we instantly thought about our energy efficient beacons, the best solution turned out to be to use a less efficient, timed beacon set to be on for only a few hours a day.
  • We are often asked what’s the best beacon for Android (or iOS) development. There actually isn’t a best one as they all advertise similar data. Instead, the best beacons are those that can be easily turned on and off to test triggering.
  • Some people ask for mains powered beacons. We aren’t aware such products exist. Instead look at USB beacons that can be powered by USB mains adapters.
  • It’s often the case people want the longest possible battery life and the smallest possible beacon. These two factors are mutually exclusive because a large battery is required for a long battery life. It’s necessary to either decide which is the most important or compromise on both factors.
  • We are sometimes asked to recommend beacons that have the best iOS and/or Android SDK. In these cases the best SDK is no SDK.

These examples demonstrate what’s right for one project isn’t necessarily right for others. This is why we stock the widest beacon range in the World.