In essence, cell phone tracking technology uses at least three already known fixed location points to determine the location of a mobile device, and the location points must be accurately identified and their coordinates recorded in a database first. Unlike landlines, considering the mobile feature of cell phones, a huge database of millions of fixed location points information need to be recorded in order to accurately locate a mobile device, and do not forget, these fixed location points should appear almost everywhere in a reasonable density.
So what could meet the above requirements, and are qualified to be considered when build a location tracking system? You may guess cell towers/base stations, well that’s absolutely right. Carriers have set up millions of cell towers around the world in order to provide phone call and SMS services to their customers, and they have a huge database of the coordinates of these base stations. And that’s why Verizon, AT&T, Sprint and T-Mobile all are selling their family locator related services which could mean huge incomes.
Another facility could be used is WiFi hotspots, as a matter of fact, a US company called Skyhook Wireless has already been setting up and integrating their WiFi Positioning System (WPS) into their location system and provide it to cell phone companies like Motorola. Skyhook Wireless has built and maintained a large global database of Wi-Fi access points to track cell phone locations over the past years.
Cell tower based location tracking, WiFi tracking and GPS tracking constitutes the most popular mobile tracking techniques nowadays.
GPS tracking is the most accurate compared to the other two. There are 24 satellites up in the sky cover the whole global, and system is made to make sure every receiver could connect to at least three satellites anywhere at the same time to provide accurate location information, the accuracy is very good, within a few meters.
However, in order to use GPS tracking service, you need a GPS/A-GPS enabled mobile device which means higher cost in the terminal. And it subjects to weather conditions which could mean slow response, and in high buildings, tunnels and garages there could be no signals.
WiFi hotspots are seen everywhere now by WiFi enabled devices, they are known to us as Access Point (AP), every Access Point has a unique MAC address and broadcast out signals from time to time. According to an article, there are 72,000+ US hotspots growing at an average rate of 40% per year. Theses hotspots are located at restaurants, train stations, airports, military bases, libraries, hotels, hospitals, coffee shops, bookstores, fuel stations, department stores, supermarkets, RV parks and campgrounds, public pay phones, and other public places which make them the perfect location points. While there are only 80,859 US cell towers growing at around 8% per year, and do not forget that 14 companies manage them.
Although WiFi tracking is less accurate than GPS tracking, but much better than cell tower based tracking, usually the accuracy is some 20 to 30 meters which is acceptable for commercial uses. The good news is that it could work indoors and it has fast response as it could not be affected by bad weather.
However, WiFi tracking has its own limitations as well. Once a mobile device goes out of range of WiFi signals, the whole tracking thing is stopped. Another limitations is that the WiFi hotspots database need to be updated from time to time, well this is a huge task. Skyhook Wireless and Google have already been surveying and collecting the location information of WiFi hotspots.
Cell tower based location tracking
According to Wikipedia, the GSM network covers an 80% of the global mobile market and it’s used by over 1.5 billion people across more than 212 countries and territories. This means the cell towers are without any doubt one of the best location points in the world, this is especially true considering the number of widely spread base stations around the global.
GSM tracking is well known to us by Triangulation, it requires nothing from the terminal, that is to say, any cell phone that connected to the cell towers could be tracked, this leads to much lower cost, and it provides fast response as well.
However, there are also disadvantages; it provides the most inaccurate results. The accuracy depends on the density of the cell towers, in downtown, the accuracy could be some 50 meters; while in urban areas, it comes to a few miles as there are less cell towers.
Another disadvantage is that the coordinate information of cell towers are known to the carriers only, and they usually won’t let other parties use their cell tower databases to provide such location based services. Well I will tell you a secret; there is a smart way to do the job. As some of you may already know, Google Maps use its client’s cell phone to collect the nearby cell tower location information, eventually Google will build a huge database of the cell towers information around the world.
Each of the three location tracking techniques has its own advantages and disadvantages, and the popular mobile tracking services use a combination of them to provide the most accurate and reliable location based services. For example, if you use Google Maps, you may notice even cell phones without GPS capabilities could use their location service, but GPS enabled mobile device produce more accurate location information.