The Infosys Labs research blog tracks trends in technology with a focus on applied research in Information and Communication Technology (ICT)

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Indoor Positioning - Ascertaining User Position

In the next few blog posts we will explore the challenges we are facing for building an Indoor Positioning System (IPS) and how are we planning to address them. If you have not already read the introduction post you can do so here

"How to find the position of a user with acceptable precision?" is the biggest problem that indoor positioning researchers are trying to solve today. Here are the reasons why it is such a big deal -. 


1.       1.   GPS doesn't work indoors

Due to signal attenuation inside buildings Global Positioning System (GPS) is not suitable for indoor positioning. In simpler words, there are too many obstacles for GPS signals to work, with precision, inside a building.

2.   Precision is critical

Imagine you register to receive an alert when you enter a specific building and you always receive alerts when you pass 100 meters away from the building! Such an Indoor Positioning System (IPS) would be a failure, to say the least. And using technologies such as cell tower results in high imprecision. While there is no documented acceptable precision number, ideal error margin should be less than 3 meters (This number may vary from a case-to-case basis).

3.   Using easily available and existing hardware

While there are multiple wireless technologies which can be used to determine a user's position inside a building, each with a different precision level, most of these technologies require the users to carry additional hardware. E.g. an idea implemented in a retail store required to install RFID tags on the carts that the users would carry. Beacons, which would be able to detect the movement of carts, were setup in the store. While this idea mitigated the need for end users to procure new hardware by installing it to the carts, it required them to pass through the beacons in a very narrow range. Otherwise the movement would not be recorded. Historically, it is known that, adoption of such technologies is very low owing to high investments expected from users and enterprises, and due to various technical constraints

 

The Solution:

A popular theoretically known solution is to use WiFi routers indoor and use method of Trilateration to find the user position. Let's examine this statement more closely:

theoretically known solution - theoretical because there is no known implementation of this method within our acceptable levels of precision under all circumstances

to use WiFi routers indoor - with the rising popularity of WiFi, almost every portable/mobile device has a receiver (and sometimes transmitter as well). This method proposes to use the WiFi routers installed inside buildings, such as malls, and receivers installed in the smartphones of the users to find the use's location

 use method of Trilateration - Trilateration is a methodology where we use a combination of models from physics and Mathematics to arrive at the actual position of the user. We may or may not translate this position to geographic co-ordinates (this is outside the scope of Trilateration).

 In further blog posts we will discuss this solution in more detail and understand how we are going to implement this as part of LBS. We will also discuss the models (from Physics and Mathematics) that we are using to achieve this.

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