Hybrid Positioning Systems: GPS, Wireless, Cell Networks, and other GNSS Systems
Definition of Hybrid Positioning Systems
A hybrid positioning system is merely one in which multiple systems are used for positioning purposes. This virtually always, though not necessarily, includes GPS, as it is at current the only global positioning network.
There are also other networks that permeate our daily lives that may also be utilized for positioning purposes, such as cell networks and wireless, which will be discussed in this article.
Of course, some people may ask why there is a necessity to use GPS in conjunction with other networks. The answer? GPS simply does not work all that well in certain environments. GPS signals are incredibly weak, and are easily degraded through processes such as signal multipath, when the signal bounces off of reflective surfaces like buildings in an “urban canyon” or attenuation, when the signal is degraded as it passes through solid materials like ceilings to get indoors.
Other positioning systems do not always have this problem. By using them in addition to GPS, greater accuracy is possible than if you just used one or the other.
Ads on TV are constantly advertising the superior networks of various cell carriers. Due to this fierce competition between them, cell coverage is getting increasingly better. Cell signals are not as weak as GPS, and so do not suffer signal multipath or attenuation to nearly the extent that GPS does, allowing their signals to penetrate deeper indoors and into urban canyons.
Use of these networks comes with a price, however. Most cell carriers require some sort of subscription fee to use their network, which almost always includes use of the hybrid positioning system on one of their cell phones. Hybrid positioning systems do not exist thus far for dedicated GPS receivers. Great accuracy comes with great cost, and not a whole lot of flexibility.
That being said, if you’re in the market for a smartphone, and you want to it to include a positioning system, this isn’t an unnecessary burden on your part. Many smartphones feature a variety of apps to make positioning much more useful to consumers, from traffic data to tracking your friends, which are not always available on dedicated receivers.
Wi-Fi & Other Wireless Systems
Wireless networks are another handy little addition to positioning systems, particularly the most common variety, Wi-Fi. The denser the population and development, the more Wi-Fi networks there are floating around, waiting to be utilized.
Wi-Fi networks are short-range, so there needs to be a lot of Wi-Fi networks to be at all useful for positioning purposes—and so this is only really possible in urban settings. Furthermore, to utilize this, your hybrid positioning system will require a database of all these possible Wi-Fi networks and their exact locations via their IP address to be able to triangulate position.
There has also been some limited use of WiMax technology, however, though it has a longer range than its sister technology Wi-Fi, it is also used less compared and so isn’t as useful.
While this leads to arguably the most accurate positioning system available, it has very limited use. Devices that may utilize this usually require some sort of subscription fee in order to use their database as well.
Probably the best example of a hybrid positioning system that utilizes wireless technology is SkyHook Wireless.
Other GNSS Systems
While at current GPS is the only GNSS system out there, GPS won’t have a monopoly for long. China’s COMPASS and the EU’s Gaileo systems are both due to come out in the next decade, and they’re set to provide as good or even superior coverage compared to the US GPS system. Russia’s GLONASS system at current is not compatible with GPS technology. There have been rumors of GNSS receivers that will be able to use multiple systems to locate themselves globally, which would provide unprecedented accuracy in those places where there isn’t cell reception or wireless Internet—although not necessarily solve all the problems inherent in just using straight GPS. However, that’s a good few years away.