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[YS Learn] LBS building blocks: Cell-tower & Wi-Fi Positioning

13th Apr 2013
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This is part of an educational series on the LBS domain. Through this series, we will explore features of Maps and location based services, potential areas and opportunities and companies that operate in the domain. The first few articles will cover the building blocks of location based services.

Decoding location based services (LBS). Image courtesy: enormlabs
Decoding location based services. Image courtesy: enormlabs

 

In addition to satellite based navigation or positioning systems, mobile handsets and tablets also use cell-tower or enhanced cell-tower positioning to quickly get an approximate position. Wi-Fi enabled devices can also use Wi-Fi positioning to determine their approximate position, depending on Wi-Fi coverage and density in the area of operation.

Network cell-tower positioning is the simplest positioning method, but delivers poor accuracy. The handset tries identifying its location depending on the BTS cell tower it is connected to. Typically, this returns an approximate positioning with a radius of uncertainty, where it is difficult to estimate the user’s exact location. Enhanced cell-tower positioning delivers better accuracy by using signal strength, position and neighboring cell information to reduce the radius of uncertainty.

Cell-tower positioning relies heavily on the cell density and coverage in the user’s area. Accuracy is better in urban areas due to higher density of cell towers, and smaller cell sites. This can stretch to several km in rural areas where cell density is thinner.

Wi-Fi positioning works on devices that have Wi-Fi capability. In a typical case, the device sends across MAC ids of all the Wi-Fi networks in range, and the server verifies this to see if there is a position associated with these.  A huge factor for Wi-Fi positioning is the density of Wi-Fi hotspots in a city/town.

Typical accuracy levels. On ground experience may vary
Typical accuracy levels. On ground experience may vary
iPad mini (WiFi only) lacks support for GPS, but makes use of WiFi positioning and cell-tower positioning to show approximate location. Image courtesty: hongkiat.com
iPad mini (WiFi only) lacks support for GPS, but makes use of WiFi positioning and cell-tower positioning to show approximate location. Image: hongkiat.com

Both cell-tower and Wi-Fi positioning are data dependent. Information is sent back to a database server that matches the fingerprints and returns an approximate position.

Most mobile operating systems offer standard APIs that applications can use to obtain position. These work across the positioning methods to offer the best possible result.Most devices, including iPads that are Wi-Fi only, and feature phones that do not have GPS support may still be use these APIs to get an approximate position for the user.

The author can be reached at shrinath@yourstory.in or @shrinathv.

With this, we finish with the building blocks series. The next few posts will decode how digital mapping works. Post this, we will explore companies in India working in the LBS space, business models and potential. If you're a firm in this space, please drop a mail to shrinath@yourstory.in for us to reach out and start the dialogue.

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