Indoor Location Tracking

Objective:

To track the location a user carrying mobile in indoor environment using GSM CellID.

Architecture

The entire process is divided into two major steps. They are:

• Offline or training Phase
• Online Phase

Offline Phase

This has been done by recording the GSM CellID at different known locations. This phase is also called “training period” and the recorded data is called “fingerprints”. When a mobile phone has to be located the current CellID measured by it is compared with the collected “fingerprints” and the new location is found out. The new location is assumed to be close to the previously collected points that have similar signal characteristics. This process is called “Finger printing”.

Fingerprinting relies on a “training phase” in which a GSM mobile phone moves through the environment recording the CellIDs. The physical position where the measurement is performed is referred as a location and the recorded Cell ID value is called as reading. The mobile phone used was Sony Ericsson K810 I and was later tested in C905 mobile also.

Online Phase

Once the training phase is completed a application measures the current Cell ID of the user and compares it with the readings stored in the Record Store. If a match occurs the corresponding locations for the measures Cell ID is returned and transmitted to PC server through GPRS. This method gives a coarse estimate of the location. Work is under progress to improve the location accuracy using ZigBee RSSI.