Prvo mali uvod:
Današnji GPS je značajno integrisan u mobilnu telefoniju širom sveta, i rapidno se širi dalje i unapređuje. Predviđa se da će u narednih par godina većina telefona imati ugrađen i GPS prijemnik, i to ne loše i neprecizne prijemnike kakvi se obično nalaze u kojekakvim prenosnim spravicama, već će takva GSM/GPS kombinacija (pominjem samo GSM a odnosi se na sve postojeće mreže - GSM/GPRS, WCDMA (UMTS) i CDMA2000) morati da omogući lociranje u najtežim uslovima (podzemne garaže, betonske zgrade, kanjoni, itd.) (a Straževica?
). Potražnja tržišta za ovakvim uređajima je ogromna, mnogo veća nego za klasičnim GPS, što navodi mnoge proizvođače da se pozabave ovim.
Hardver (samo deo onoga što trenutno postoji):
Starija varijanta čipseta zvanog "Global Locate A-GPS chip-set" u sebi ima preko 20.000 korelatora, što mu omogućava da odradi velike proračune i da pronalazi satelite kojima je nivo signala ispod -158dBm, potrošnja mu je minimalna, a interval korekcije oko 250 milisekundi.
Najnovija varijanta čipseta "SiRFStar III" ima oko 200.000 korelatora i osetljivost od -159dBm. SiRFSoft GPS arhitektura omogućava integraciju u sve moguće prenosne uređaje (Intel XScale, OMAPI, PDA, GSM/Cell/Smart telefone, itd).
Rezultat ovakvog spoja - stotine miliona ljudi će u svakom trenutku kod sebe imati GPS prijemnik izvanrednih mogućnosti i karakteristika. Kako su zgodno napisali na jednom sajtu - "GPS and GSM go together".
Ovo datira od marta 2004.: "With a GPS phone you can tell your exact location and with the right service of the phone operator you can even project your position on a map in your friend’s cell phone. The service will tell you where you could meet and by which route to get there."
Ovo su neki od 3G telefona koji imaju GPS - Motorola A835, A920 i A925, NEC e313 i e616, zatim "World cell phones" - Motorola A840 i LG W800, pa Nokia modeli - 5140 (Xpress-on GPS Shell), komunikatori od modela 9210 uz pomoć add-on modula LAM-1, Motorola iDEN i58sr/i88s/i710/i730/i830 na Kanadskoj Telus mreži, Nextel i58sr, i88s, i530 i i730 (TeleType), itd.
U zemljama gde postoje "Locate Services", mobilni telefon može da odredi gde se nalazite i da prikaže mapu na ekranu, zatim, ukucate odredište i dobićete označenu rutu od polaznog mesta, tačno vas navodeći kuda treba da idete. U Engleskoj, pored opcije "od tačke A do tačke B", postoji još i "My Nearest" (pronalazi najbliže banke, bankomate, prodavnice, restorane, pumpe, itd.), zatim "Business Finder" za pronalaženje raznih firmi i preduzeća i "Quick Map" - kompletan adresar Engleske (deo ovoga je već pušten kod nas u nekoj varijanti).
U jednom od ranijih postova sam objašnjavao kako radi GPS, a ovo neću prevoditi, vežbajte malo engleski:
A-GPS explained in historical context
Introduction to Assisted-GPS (A-GPS)
When the U.S. Federal Communications Commission (FCC) in 1996 ordered that cellular phone carriers had to route 911 calls to a Public Safety Answering Point (PSAP) with Automatic Location Identification (ALI), it recognized that, at that time, technology did not exist that could provide detailed caller-location information.
Handsets with a GPS receiver incorporated seemed excluded, because
- after launching a 911 emergency call it would take the receiver several minutes to establish a fix (cold start) and being able to output the caller’s location co-ordinates
- GPS would have a very poor performance in too many situations (indoors, under dense foliage, in (urban) canyons, etc).
- a GPS receiver would drain too much power from the handset
- incorporating a GPS receiver in the handset would be far too expensive and too bulky.
Network-based Solutions
Often used abbreviations:
BTS = Base Transceiver Station (the cell tower)
ID = Identifier
LMU = Location Measurement Unit
MS = Mobile Station (the handheld)
MSC = Mobile Switching Center
PDE = Position Determining Entity
Network Location Technologies
Cell-ID: Cell Site (BTS) Identification. Most basic wireless location technology. Latitude/longitude of BTS is taken as the MS location. Available on all networks. Relative accuracy depends on size of cell. Accuracy: 100-3000m.
AOA: Angle of Arrival. This method uses multiple antennas at a BTS to determine the incident angle of an arriving signal from a MS. The information of two BTSs allow to calculate the position of the MS. This technique is very sensitive for multipath signals, that have to be accounted for. Installing and aligning antenna arrays on base stations can be a sensitive and costly process. Accuracy: 100-200m.
TDOA: Time Difference of Arrival. One of the simpler network-based methods, TDOA uses the time it takes for a signal to travel as an indirect method of calculating distance. With a minimum of three base stations receiving a signal from a handset, triangulation can determine the position of the MS. To achieve accurate positioning, the base stations must be precisely synchronized in time, which is usually done by GPS. Accuracy: 100-200m.
TOA: Time of Arrival. Similar to the TDOA technique, this technology only differs in that it uses the absolute time of arrival at a certain BTS rather than the difference between two stations. Three BTSs are required to resolve the precise position of a MS. Synchronization of the network base stations is important. Accuracy: 100-200m.
E-OTD: Enhanced Observed Time Difference. This method includes new technology in the handset to assist in locating the unit in a network. Handsets in an E-OTD system are set up to support positioning in a network where base stations are asynchronous. One implementation of this method has the handset reporting back measured times from three base stations to be combined with timing data from various points in the network (LMUs) in order to determine the MS location. Accuracy: 50-200m.
A-FLT: Advanced Forward Link Trilateration. This method of location is unique to CDMA (code-division multiple access) networks, since they are inherently synchronous in their operation. It measures the phase delay between signals sent to a pair of base stations and then compares this to the same data taken from another pair. Data of three base stations can be used to positively locate a MS. Accuracy: 50-200m.
OTDOA: Observed Time Difference of Arrival is similar to E-OTD, but may provide lower yield (percentage of successful position determinations) and operates only on UMTS networks. Accuracy: 50-200m.
Invention of A-GPS
Even before the 1996 FCC ruling about 911 emergency calls, Giovanni Vannucci of the Wireless Communication Research Department of Lucent Technology’s Bell Labs had begun thinking about the problem. He realized that it was possible to use GPS satellites to pinpoint wireless telephones making calls. Up till then GPS was considered unsuitable for wireless 911 applications (see Introduction).
Vannucci teamed up with Bob Richton of the Wireless Technology Laboratory to find a way to circumvent these problems. They came up with the W.A.G. (Wireless Assisted GPS) method, which makes use of a mobile phone with a scaled-down GPS receiver. The mobile receiver picks up signals from some of the GPS satellites that are simultaneously seen by a reference GPS receiver, connected to the wireless network.
The network sends GPS information it has picked up to the mobile handset, which uses this information to detect GPS signals from the satellites. The mobile handset then returns data about the signals it received to the network, where it is used to compute the handset’s location. Since the calculation of the exact position is done within the network, the handset doesn’t need to be complex and expensive.
Hybrid Technology
Hybrid location technology combines A-GPS with other location positioning (see above) in a way that allows the strengths of one to compensate for the weaknesses of the other to provide a more reliable and robust location solution. Common hybrids are: A-FLT/A-GPS, E-OTD/A-GPS and Cell ID/A-GPS.
The most straight-forward implementation of Hybrid technology for GSM, GPRS and UMTS networks is to combine A-GPS with Cell ID. This improves yield in areas where A-GPS cannot produce position information and provides the accuracy of A-GPS in all other cases. A-GPS coverage and accuracy is typically excellent just about anywhere a subscriber can go, degrading only deep inside buildings or in dense urban areas where Cell ID may still be able to produce a position.
Typically, these are areas where cell density is high, so Cell ID will be at the more desirable end of its accuracy range, though it will not be as accurate as A-GPS.
A-GPS requires precise time to perform satellite signal processing. It can utilize precise time from a synchronized network (which provides optimized TTFF and sensitivity), or derive it on either a synchronized or an asynchronous network from aiding data received from the Location Server. A-GPS operates on any air interface network, synchronized or not, without requiring any costly equipment to derive time, and will operate with enhanced efficiency and performance on precisely synchronized networks.
:!: E, ovo dalje je vrlo bitno, jer upravo objašnjava kolika je prednost u odnosu na samostalan GPS uređaj :!:
A combination of two complementary technologies
What makes Assisted-GPS work so well is that the wireless network, using its own GPS receivers, as well as an estimate of the handset’s location down to cell/sector, can predict with great accuracy the GPS signal the handset will receive and send that information to the handset. With this assistance the size of the search space is greatly reduced and the time-to-first-fix (TTFF) shortened from minutes to seconds. In addition, an A-GPS receiver in the handset can detect and demodulate signals that are order of magnitude weaker than those required by conventional GPS receivers.
An example is SnapTrack’s hybrid A-GPS location solution, which takes advantage of the complementary nature of both network and GPS solutions by using both cellular/wireless network information and the satellite-based GPS information to directly improve the positioning availability, sensitivity, accuracy and time-to-fix. By combining the two information sources, SnapTrack’s hybrid solution can provide a position fix with as few as one satellite and one cell site.
A sad malo vesti u proteklih par dana, da potkrepe celu priču:
12.01.2005.: SiRF Technology Holdings, Inc., a leading provider of GPS-enabled location technology, announced its patented, high performance SiRFLoc MultiMode aided-GPS technology has been licensed by Research In Motion (RIM) for use with the SiRFstarIIe/LP chipset. RIM's BlackBerry 7520 device incorporates GPS technology from SiRF to help support a wide range of location, tracking and navigation applications.
11.01.: The Siemens Communications Group has developed a new solution for the Assisted Global Positioning System (A-GPS) which will allow mobile operators to integrate the new navigation technology into their mobile networks far quicker than before. T-Mobile Czech Republic a.s. is currently testing the Siemens solution in Prague. The terminal used is the SX1 phone from Siemens which was fitted with an A-GPS chip specially for the field trials. Siemens' IP-based A-GPS solution will be on the market from the 3rd quarter of 2005. Current standardized A-GPS solutions require costly intervention in the mobile network, as the infrastructure has to be adapted to the 3GPP Location Services standard. The IP (Internet Protocol)-based A-GPS solution from Siemens, on the other hand, comprises a special location server that can be integrated directly into the mobile network and communicates with the mobile terminal via an IP connection.
Ima još!
07.01. Reflecting the trend towards the increased integration of connectivity and mobility, Nokia has dedicated the majority of its consumer Electronics Show (CES) 2005 booth space to in-vehicle products, including wireless car kits, Bluetooth-enabled GPS receivers and Nokia hands free solutions for the auto industry. In addition to in-vehicle devices, other exciting Nokia accessories and peripherals will be on hand. Nokia will also be highlighting its new battery authentication program, designed to give consumers a way to differentiate original Nokia batteries from potentially unsafe counterfeit batteries. On the show floor, Nokia is displaying a 2005 Land Rover LR3 with Integrated Bluetooth Phone System that allows a compatible phone to be controlled via a vehicle keypad, voice recognition or steering wheel controls. Also on display is a new Mini Cooper with a Nokia Wireless Car Kit CK-7W installed. Fully hidden from view, except for a tastefully designed dash- mounted control button, the Nokia Wireless Car Kit demonstrates the seamless aftermarket installation that is possible, even in the most diminutive of vehicles.
05.01. Garmin International Inc., a unit of Garmin Ltd. , introduced the GPS 10, a sensor that receives location data from the Global Positioning System (GPS) and transmits that information to mobile devices enabled with Bluetooth wireless technology. The GPS 10 is compact (WxHxD: 1.8" x 3.5" x 0.8") and lightweight (2.8 oz.). It integrates a 12-parallel channel, WAAS-enabled GPS receiver and a Bluetooth transceiver to provide location data to a variety of mobile devices. The GPS 10 has a magnetic base and is waterproof, so it can be mounted inside or outside a vehicle. The sensor has an internal lithium-ion battery and the Deluxe package includes a 12-volt adapter, allowing the GPS 10 to run on its own power for up to 10 hours or on the vehicle's power.
E, dosta je bilo... možda vam ovo pomogne da shvatite koliko je lako pronaći ukraden telefon, samo kad neko hoće da se potrudi...
Ali se istovremeno ježim od pomisli da će u budućnosti na ovome biti zasnovan neki čip koji će se implantirati u ljude... brrr...