For the Open IoT Challenge 4.0 we propose a “trusted indoor positioning system for nursing homes” but, first of all, it is necessary to ask ourselves, do we know what is this?. In these first entries, we will try to explain it in a simple way.
The basis of our proposal is an Indoor Positioning System, IPS, which is a system capable of positioning people or objects inside buildings. Let’s assume a building plan like the following.
An IPS would allow us to know remotely the location of people or objects in this building. From now on we will refer generically to the location of elements, understanding that an element could be anything either people or objects.
For our IPS Proof of Concept, PoC, we will use some wireless technology such as wireless networks or Bluetooth. We have opted to use Bluetooth Low Energy beacons, BLE beacons, hereafter beacons.
These beacons allow us to calculate the distance by measuring the attenuation of the signal power. The simplicity of these devices, their low cost, low weight and low energy consumption makes them the perfect candidates for the PoC of our IPS.
Usually, the IPSs based on beacons use fixed advertisers and mobile scanners (commonly smartphones). This occurs thanks to i) systems that can work for years using small batteries, ii) the small number of Bluetooth signals in the particular environment or iii) greater anonymity of the users.
Reverse IPS based on beacons, with fixed scanners and mobile advertisers, are less common since they imply several limitations such as i) the Bluetooth signals interfere with each other so the number of elements to be positioned is limited, ii) the IPS calculates the position of the elements, so it scales worse, iii) lower anonymity of the users, iv) higher energy consumption of the system, among others.
However, if the above limitations are not a problem for a specific solution to be deployed, two interesting properties should be considered:
- Carrying a device of reduced size, weight and long-life battery, an element can be positioned for years.
- The IPS captures the signals, so it can trust them. This property is one of the bases of our proposal. We will write about it in the next entry. For now, it is enough to say that in our approach we will develop a kind of IPS which has this property.
In order to deploy our IPS, we will need to install scanners in the buildings. These scanners can be any kind of programmable devices with BLE and network connectivity. We believe that Low Cost Single-Board Computers, LCSBC, are the best option. The location and number of scanners to be used in each building should be analysed in each particular case.
The following image shows the same building plan with four scanners (grey boxes hanged on the walls), which could be four LCSBC.
Locating the scanners in the building and calibrating the IPS, any element equipped with a beacon advertiser can be scanned by the system. In our case, the elements to be positioned in the building will be people, each one carrying a beacon advertiser. These devices emit BLE signals that can be captured by the scanners and so, each particular element in the building can be located by the system.
In our proposal, the scanners publish the captures to a general log. A service capable of positioning each element using the captures will be subscribed to this general record. To build the proposal, we will analyse different factors such as the most appropriate beacon protocol, the most suitable LCSBC, the best IoT protocol for our IPS, the positioning accuracy or the technology stack to be used.
In order to carry out the analysis of these issues, we are currently developing PANAL ( from Position ANALyzer) the Spanish term for honeycomb. We will write about this resource in the coming weeks.
PANAL is currently a set of Eclipse Kura components that will allow us to i) configure an LCSBCs either as a beacon scanners or as a beacon advertiser by using different protocols (Eddystone and iBeacon), ii) build datasets, iii) test different positioning algorithms, iv) measure the positioning accuracy and v) calibrate the IPS.
In the next post, we will continue explaining the pillars of our proposal, addressing one of the most interesting and challenging issues, how we are going to approach the construction of a Trusted IPS.