Reliable and precise tracking of devices and assets has triggered the deployment of Location Based Services. Today, LBS is available for a wide range of applications from fleet and traffic management, security, personal navigation, advertising, and marketing, asset and people tracking to theft recovery. Many more new applications are in the making every single day. The acquisition and accurate updating of the device position information in a short time period is a key factor to all these applications. To provide an effective solution it is necessary to determine device position in indoor as well as harsh outdoor environments, such as urban canyons and mountains. The severity of the environment requires a more complex system to overcome the challenges hence multiple technologies are used in tandem to determine the location to the best possible accuracy.
This article throws light upon some of the techniques that are used in mobile devices in order to acquire its device position. Once the location is determined the data is usually sent over a cellular network to the application software.
The necessity for location based services
Location based services are crucial in today’s lives and they are used in a multitude of applications. Some of the most common used of Location Based Services include the following:
Technologies used for location based services
The most commonly used technology to determine position is GPS-GNSS. This technology is cost effective and low-power solutions; it is suitable for integration in mobile devices and is now readily available. However, GPS-GNSS technology works reliably when there is a clear view of the satellites. In cases when the satellite view is obstructed the performance becomes unpredictable. In order to overcome this limitation of GPS-GNSS devices, several assistance techniques have been developed in order to ‘assist’ the GPS-GNSS device in performing and speeding up the position computation. All these ‘assisting’ techniques use some communication network (Ethernet, Wi-Fi, Cellular and so on) in order to provide additional data to GNSS device. These ‘assisting’ techniques are often called Assisted-GPS (AGPS or A-GPS) because they have been developed with the aim to assist GPS receiver. AGPS allows mitigating these limits by providing the GNSS device with crucial data to speed up the position fix, like, time, Almanac and Ephemeris.
Cellular networks and Wi-Fi hot spots being used for finding location data
When the location data cannot be acquired using GPS-GNSS, a less accurate position can be obtained using the cellular networks. By using the cellular networks’ measured parameter and other methods such as BTS triangulation it is possible to provide an estimate position. In indoor environments where GPS-GNSS might not be able to obtain a fix, this technique is used very effectively.
Finally, Wi-Fi hot spots are also being used to estimate position. This technique is widely used in indoor environments such as large malls and buildings. In recent smart mobile devices, a software layer referred to as Location Based Software (LBS) very intelligently combines data from all of the above techniques along with recent location data and state-of-the-art motion sensors to provide an acceptable solution for most of the LBS applications. Yet another technology used in limited geographical areas in the US in the agricultural industry for precision farming, where location data to a very high level of accuracy is required is (Real Time Kinematic) RTK networks.
