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There is one thing that pigeons can do better than cellphones at present, and that is to know where they are. That will hopefully soon change. And, no, it does not mean that cellphones will come with a built-in carrier pigeon that is trained to fly to the closest police station when their owner gets into trouble!
Many people associate location technology with the US FCC mandate to locate 9-1-1 callers. But there are two other potential uses as well: law enforcement and commercial applications. Now is a critical time for location technology, where the price and performance must meet critical benchmarks and it must be determined which user pays for what.
The FCC 9-1-1 mandate has two location components, to first provide information about the cell or sector from which a 9-1-1 call was made (by 1998), and then to provide 125 meter/400 foot accuracy (by the year 2001). In the future, as technology advances, the FCC may tighten the accuracy requirements, and may include height as well as latitude and longitude. But the FCC mandate has a loophole – the PSAPs have to indicate a readiness to receive location data. If they feel that the technology will be too expensive for them, or not reliable enough, they may not ask for wireless carriers to support the mandate.
Apart from cost and accuracy, another critical issue is whether existing wireless phones will need to be upgraded. GPS, for example, provides high accuracy in relatively open areas (where the phone has the required clear view of multiple satellites) but would require a phone upgrade or, more likely, an entirely new phone. The FCC has been coy on whether a terminal-based solution will be acceptable (I could quote what the FCC said, but it would be embarassing if you understood it and I didn’t).
A network-based solution requires radio receivers to be placed strategically around the coverage area (possibly, but not necessarily, co-located with cellsites). The accuracy of the position fix varies with the distance and orientation of the nearest measuring stations. The problem with the network approach is the cost of the many receiving stations required, without which sufficient accuracy cannot be obtained. The advantage is that it will work with existing phones. However, each technology (analog, TDMA, CDMA) requires a different approach. Analog phones are the easiest to locate, because an entire 30 khz (10 khz for N-AMPS) is dedicated to a single mobile. TDMA maintains the 30 khz bandwidth, but requires the monitoring equipment measure only during the monitored mobile’s assigned timeslots. Plus, TDMA supports temporary mobile station identifiers (TMSI) that obscure the true identity of the mobile (making communication with the MSC mandatory). CDMA – the most complex wireless technology, and the one technology explicitly designed to avoid eavesdropping – is, not surprisingly, the hardest technology to track. Many CDMA phones and cellsites share the same 1.25 Mhz frequency band, all transmit simultaneously and they rapidly change power levels.
The choice of a solution will make a big difference to law enforcement, which appears likely to get access to the same location tracking capability as 9-1-1 (although only with certain types of court orders), at least according to proposals in the latest FCC Notice of Proposed Rulemaking on CALEA. If a handset-based solution is chosen, the wireless phone user would be able to know when they were being tracked, which would make this solution much less useful for law enforcement. A network-based solution should be completely transparent, and thus much more useful for the boys (and girls) in blue.
The greatest variety of applications lies within the commercial realm, although most are, at best, being field trialed, and have not yet been proven. One of the most talked about is Location Sensitive Billing, which could allow users to have lower airtime rates in the vicinity of their home or office or in a campus environment. Currently, these applications can be based solely on the serving cell or sector, the size of which varies greatly, from areas with a high call volume (with cells covering tiny areas, and with many sectorized cells) to areas with a low call volume (with cells covering huge areas). If E911 technologies can routinely delivery 125 meter accuracy, then a user can be located not within their home, but at least within a block.
There are a number of other consumer-oriented services being discussed. Enhanced 4-1-1 will enable phone numbers to be provided for businesses in the desired category closest to the caller’s location. There may be specialized versions of this, where the business category is implied by the dialed digits (e.g. *AAA could call a roadside emergency dispatcher, and direct the tow truck to the location of the breakdown). A navigation service could provide directions to a specific address, knowing where the caller is. So, ET will be able not only to call home, but to get directions (“turn left at Alpha Centaur...”).
More mundane (but possibly more lucrative) location services will be aimed at businesses, not consumers. Cellphone transceivers could be used for wide area tracking of vehicles or freight containers. Even people could be tracked in this way, most likely criminals under house arrest or medical patients with disorders that cause them to wander and get lost (such as Alzheimer’s). Users of stolen wireless phones could even be tracked, to help with recovery of not only the phone, but of the cost of the calls made with the stolen phone.
There is no question that the range of applications for location technology is wide, but its success is still not assured. The biggest questions revolve around cost and capability. Every segment of the market with an interest in location technology can think of a good reason for another segment to pay for the infrastructure. The 9-1-1 community is not anxious to pay to bring wireless phones up to near the same level of functionality that wireline phones currently provide at a fraction of the cost. The law enforcement community is hoping to piggyback on an existing (and paid for) infrastructure. And carriers certainly hope that commercial services will prove to be a big money spinner – but they certainly do not know that yet. While it is certain that youthful location technologies will continue to increase in performance as they lessen in price, it is not certain that the wrangling over funding will be resolved any time soon.
I have to close out now ... my cellphone is chirping and wants to be fed.
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