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A-GPS explained in historical context

Introduction to Assisted-GPS (A-GPS)

The original meaning of A-GPS was different than today's

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.

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.

SnapTrack’s multimode technology offers additional functionality to the basic Assisted-GPS (A-GPS) architecture. The multimode system can work without assistance from the wireless network. In this mode, it operates similar to conventional GPS but with dramatically increased sensitivity.

SnapTrack’s SmartServer Hybrid Wireless Assisted GPS (A-GPS) solution offers an average of 15dBm of additional receiver sensitivity, and 20-30dBm in hybrid CDMA-based configurations. (We have no affiliation with SnapTrack).

Historical A-GPS related facts

We have traced 4 companies, who already in 1998 developed E-911 (Enhanced 911) technology, based on GPS: Enuvis or A-GPS: SnapTrack, Global Locate and Traxsis.

March 22, 1999. Motorola announced its Wireless-Assisted Global Positioning System, which includes server technology and an embedded receiver solution to enhance traditional GPS performance for telematics systems, particularly in urban canyons and under dense foliage.

June 28, 1999. SnapTrack presented its ‘FCC Location Roundtable’. Herein is described SnapTrack’s Personal Location Technology:
Combine GPS receiving capability with a cell-based wireless network
-Air interface independent
Divide location determination task between client and server
Extract key information from the wireless network
-E.g., approximate location, carrier frequency
Software-based solution
-Use phone’s own DSP chip to rapidly process an information-rich snapshot of GPS data using fast convolution software. ‘SnapTrack Wireless-Assisted GPS (A-GPS) can achieve accurate fix with only a single base station as long as cell phone can communicate’. We also read that SnapTrack had already done tests in 1997. One in the U.S. and one in Japan.

August 2, 1999. Lucent Technologies Inc. is awaiting word from FCC that its handset-based location product satisfies E-911 Phase II requirements. But that shouldn’t be a problem.

Location technology proposals from Integrated Data Communications Inc., SiRF Technology Inc., SnapTrack Inc. and Lucent are based on handsets.

Lucent’s handset partner in its location race, Qualcomm INC. participated with SnapTrack in a discussion July 26 with FCC officials.

August 15, 1999. SiRF Technology announced a new architecture (SiRFstarII) designed for more-accurate positioning, faster signal acquisition and better performance when applied in tough locations like deep foliage and urban canyons. SnapTrack announced a licensing deal with Texas Instruments Inc., to jointly integrate SnapTrack’s network-assisted GPS (A-GPS) technology with TI’s DSP platform for digital wireless systems.

While SiRF offers a fully featured, autonomous GPS solution in the form of chip set and core, SnapTrack offers carriers and handset vendors software that uses the network to aid in GPS tracking. The world’s largest wireless carrier, NTT DoCoMo in Japan, will integrate both the SnapTrack and SiRF technologies into its DoCoMo Location Platform.

Spring 2000. Qualcomm acquired SnapTrack.

December 1, 2000. Based on handset-availability projections from Motorola, Nextel wants to begin selling assisted GPS (A-GPS) handsets in October 2002, one year later than the FCC’s starting date.

December 2000. Sprint PCS announced it will be using a handset-based GPS solution from Qualcomm Inc. to fulfill the requirements of the FCC E-911 Phase II mandate. Qualcomm’s gpsOne solution, which features SnapTrack’s Wireless-Assisted GPS, has proven to be the world’s most accurate, all-environment means of pinpointing callers who make emergency calls from their mobile phones. Sprint PCS will begin offering the wireless-assisted GPS-capable handsets in the second half of 2001.

February 13, 2001. NEC Corporation and SnapTrack Inc have jointly developed a wireless location device (uPD77533) that uses the Global Positioning System to provide accurate location information for applications in mobile handsets and other wireless devices.

With SnapTrack’s technology, final position calculations are performed on a location server using GPS measurements provided by the chipset in the mobile device, reducing the processing and power consumption burden on the device, while enhancing accuracy and response time.

August 7, 2001. CellPoint Inc ;, a global provider of mobile location technology and services, and SiRF Technology Inc ;, a leading developer of location technology based on GPS, announced a strategic partnership to deliver a platform to GSM cell phone operators that provides highly accurate location information to cell phone users in any environment.

SiRF’s Assisted GPS (A_GPS) technology will be integrated with CellPoint’s network-based Enhanced Cell-ID (E-Cell-ID) location platform technology, providing consumers and network operators the best of both location-information systems. A hybrid of GPS and network-based technology offers constant, accurate location information anytime, anywhere.

December 10, 2001. Agilent Technologies Inc. introduced the industry’s first commercial calibration system for Qualcomm’s gpsOne hybrid position location system, the world’s only all-terrain, high-availability solution for locating mobile E-911 phone users.

The Agilent Time Offset Precision Calibration system measures and characterizes a base station’s timing delay, enabling more accurate positioning of mobile phone users in high-blockage environments such as indoors or in urban street canyons.

Positioning location tracking applications for mobile phones, such as E-911 and other emergency location applications, mapping applications, navigation and position-enabled services, are powered by Qualcomm’s revolutionary SnapTrack-enabled hybrid gpsOne position location technology.

The gpsOne solution, the world’s first hybrid wireless assisted GPS-based system, uses both GPS ranging information and Code Division Multiple Access (CDMA)-based pilot information to provide accurate all-terrain position location capability.

December 17, 2001. NovAtel inc. announced that its OEM4 Global Positioning System receiver is a core component of the SnapWARN Wide Area GPS Reference Network deployed by SnapTrack Inc., a wholly-owned subsidiary of Qualcomm Inc.

The NovAtel OEM4 GPS receivers are used in SnapTrack’s commercially available SnapWARN GPS data feed service to provide constant, high quality GPS satellite information in support of gpsOne-based wireless location systems operated by wireless carriers in North America.

The SnapWARN system consists of an interconnected network of NovAtel OEM4 GPS reference receivers sited around the U.S. and fully redundant communications links connected to data gateways and location servers operating SnapSmart Position Determination Entity (PDE) software for Qualcomm’s gpsOne position location solution, enhanced by SnapTrack Wireless Assisted GPS (A-GPS) technology.

SnapTrack is focused on integrating GPS and two-way wireless technologies. SnapTrack’s patented architecture offers anytime, anywhere, accurate, high-speed location of a wireless caller, even inside buildings where conventional GPS does not operate.

December 20, 2001. Benefon recently began selling a solution that combines a cellular phone and GPS receiver.

Israeli start-up CellGuide has come up with a different solution. CellGuide’s A-GPS-based product can be installed in existing cellular telephone chips, which means they can be installed in current generation telephones, as well as next generation ones.

February 25, 2002. CellPoint Inc. (not CellGuide), a global provider of mobile location software technology and platforms, and Benefon Oyj, a leader in mobile telematics instruments, have signed a cooperation agreement on a joint program to provide Assisted GPS (A-GPS) location solutions to GSM, 2.5G and 3G network operators this year (2002).

Both companies are convinced that the combination of cell-based network location methods and A-GPS is the most powerful and cost-effective way to provide E-911 and E112 emergency location solutions.

March 14, 2002. Global Locate recently introduced its GL-16000 GPS processor, which it claims is the first technology able to pick up signals indoors and uses negligible battery power; less than .0005 percent of the cell phone’s charge per location fix. The tiny chip is manufactured and co-branded by Fujitsu Microelectronics.

According to Global Locate, a significant feature of the system is the ability to set up a buddy list, authorizing exactly who can track the location of a phone. Except for 911 emergency services, a person cannot be tracked by other cell users whose numbers have not been programmed into the phone carrying the GPS chip.

May 22, 2002. Marking another achievement in meeting E-911 Phase II targets, Verizon Wireless, operator of the largest wireless network in the U.S., said it is launching another wireless phone with an embedded GPS receiver, the 9155-GPX from Audiovox Communication Corporation, at the end of the week. Another E-911 capable phone, the SCH-N300 from Samsung, has been available from Verizon Wireless since December, 2001.

October 1, 2002. Axiom Navigation Inc, producer of GPS technology, has acquired Traxsis, a provider of software that locates mobile users connected to cellular networks. The combined company will offer products that allow cellular telephone users to use many location-based services (LBS). The product will also support the E-911 initiative, allowing users to transmit their position in an emergency.

October 30, 2002. Nokia Early Stage Technology Fund portfolio company Indagon Ltd., a developer and producer of high accuracy GPS-based positioning solutions introduced the first mobile telematics device for fleet management utilizing assisted GPS (A-GPS) in GSM, GPRS and TETRA networks. Indagon’s new MTT 110 positioning device is based on Fastrax iTrax02/8, a programmable 12-channel GPS receiver with the lowest power consumption on the market.

November 2002. SnapTrack is now working with Alcatel to provide location-based services. SnapTrack’s Assisted-GPS wireless-location server software will be incorporated into Alcatel’s Intelligent Networks products.

A signed development agreement combines Trimble Navigation’s GPS technology with Voxson’s GSM/GPRS wireless communications modules. By merging their technologies, these two companies plan to offer small, low-powered, location-enabled communications functionality for wireless mobile products.

February 4, 2003. Six million Assisted GPS (A-GPS) handsets were sold on a global basis in 2002. CDMA carriers Sprint and Verizon have led the effort to implement A-GPS services, and at the end of 2002, more than half of the handsets available from these two carriers were A-GPS-enabled.

KDDI of Japan was the world’s leading GPS carrier with 4 million users at the end of 2002.

February 12, 2003. SiRF Technology Inc announced it had signed a definitive agreement to acquire Enuvis Inc, an innovator in wireless location technology, to further its mission of providing end-to-end location technology systems to wireless operators and carriers worldwide.

SiRF will integrate Enuvis patented UrbanGPS assisted GPS (A-GPS) technology into its SiRFLoc multimode location platform, adding the ability to acquire GPS signals and deliver high accuracy location calculations in even more environments, such as inside buildings and dense metropolitan areas where other GPS technologies fail.

SiRFLoc Multimode is the first wireless carrier-grade location platform that allows device users to determine their position with or without network aiding.

March 17, 2003. Wireless chip specialist Global Locate launched a novel Assisted-GPS (A-GPS) chip set featuring 20,000 hardware correlators on a fully-integrated RF device with a time-to-first-fix of just 250 milliseconds.

The Global Locate A-GPS Chip Set includes the GL-20000 GPS baseband processor IC and a low noise integrated front-end IC, dubbed the GL-LN22. The device can acquire satellites with a signal intensity as low as -158dBm. The GL-20000 A-GPS can also operate without server aiding, and also provides multiple mode operation, either MS-Assisted, with position calculation at server, or MS-based, with position calculated in the handheld.

July 22, 2003. Kyocera Wireless Corp., a leading manufacturer of CDMA wireless devices, announced that its Kyocera 200 Module has completed the Verizon Wireless certification process. The device, which is the only wireless module to incorporate both trimode CDMA2000 1XRTT high-speed voice/data and assisted-GPS (A-GPS) position location technologies, is designed to enable machine-to-machine (M2M) and telemetry applications.

M2M wireless telemetry is the transfer of data over a wide-area, wireless network between two or more non-mobile or mobile machines.

September 10, 2003. Motorola launched a miniature Global Positioning System product capable of supporting autonomous as well as assisted-GPS operation. The dime-sized FS Oncore can be used for adding location sensing to portable electronics products such as cell phones or PDAs. It calculates its position locally, eliminating network overhead and problems that are connected with network-centric GPS systems.

October 14, 2003. Motorola’s 3G cell phone A835 comes with Bluetooth, a built-in digital camera for video conferencing, and Assisted-GPS (A-GPS). Available from 3 in the UK, Sweden, Austria, Australia, Denmark, Hong Kong, and Italy.

October 16, 2003. Alcatel has been selected by Bouygues Telecom to configure and test the Alcatel 8607 Assisted-GPS Positioning Server in the Bouygues Telecom mobile communications network.

Alcatel is the first communications network supplier to bring high accuracy Assisted-GPS (A-GPS) positioning to the GSM mobile networks market. Alcatel’s solution is the only commercially available solution that fully supports 3GPP location standards and works with any vendor’s 3GPP compatible Assisted-GPS handsets, MSCs (Mobile Switching Center) or BSC (Base Station Controller).

November 13, 2003. Bell Mobility, Canada’s leading wireless provider, announced the latest offering in its suite of innovative Location Based Services (LBS). Bell Mobility’s popular Roadside Assistance service has been enhanced to include location based technology, bringing increased safety to the fingertips of its customers, wherever they are located.

Assisted GPS (A-GPS) technology enhances Bell Mobility’s Roadside Assistance service by combining the accuracy of both cell sector location technology and GPS technology. This ensures the customer can be found with more reliability than with traditional GPS services.

December 15, 2003. Sony Electronics announced the industry’s first single-chip CMOS Global Positioning System LSI that incorporates a built-in RF circuit in an ultra-miniature design.

Capable of stand-alone and network assisted signal detection of up to -150dBm, the new LSI achieves high sensitivity that enables even indoor reception of GPS satellite signals. Combining hot start positioning time of two to six seconds and power as low as 50mW during tracking, the device achieves optimal power management and high performance.

January 15, 2004. Three has added a unique feature to the list of services available to customers in several markets. The 3GEO mobile navigational system turns a customer’s handset into a perfect travel companion by allowing quick and exact location searches. Maps available on the screen allow customers to find what ever they are searching for. This service is available in Austria, Denmark, UK and Sweden, and will become a key feature of 3 services in other worldwide 3 markets later.

The precise location by Assisted-GPS is derived through a number of steps that are hidden from the customer. The first step is the handset receives an approximate position, derived from approximate network position combined with date from the GPS satellites. Then the final accurate position is derived from data received from a number of satellites. This exact position is then delivered over the 3G network in real-time, to allow the delivery of position sensitive customer information back to the customers handset.

January 15, 2004. Hutchinson CAT Wireless MultiMedia Limited, the marketing service provider of CDMA2000 1X technology in Thailand under the brand ‘Hutch’, has scored an important first in South East Asia with the introduction to the Thai mobile customers of its new ’Navi’ A-GPS based service to enable the ‘Navi’ subscribers to enjoy a host of location based applications.

Navi by Hutch service utilizes Qualcomm’s gpsOne hybrid Assisted GPS technology and the solution co-developed by Hutch and Navitime-Japan. The A-GPS solution utilizes both GPS satellites and the CDMA2000 1X base stations together with the sophisticated calculation algorithm to get the location fixed on a mobile subscriber. With this forefront technology, the solution is able not only to provide highly accurate position up to within 10 meters but also can locate the people when they are indoors where the access to GPS satellites is insufficient.

January, 2004. Spirent Communications has released a single-source product for automated testing of GSM and WCDMA handsets that support Assisted-GPS (A_GPS) location technology. GSM and UMTS network operators around the world are beginning to deploy high accuracy location technologies, one of the most popular of which is Assisted-GPS (A-GPS).

February 20, 2004. NEC Corporation announced that it would introduce the Location Information System (LIS), which provides the best LCS solution for GSM operators and a variety of user-tailored systems. NEC’s Location Information System is based on highly accurate A-GPS positioning methods.

NEC is the pioneer of A-GPS solutions and has wide experience in developing location-based service systems for not only Japanese but also world wide operators. NEC has made a proven and valuable contribution to the commercial mobile location network services of the world’s leading mobile carriers, including NTT DoCoMo, KDDI and Hutchinson CAT Wireless in Thailand.

February 23, 2004. Infineon Technologies announced the availability of a multimedia phone platform that concurrently supports UMTS, EDGE and GPRS cellular standards. When used in UMTS configuration, the platform automatically switches between UMTS and EDGE reception, depending on network availability. Furthermore, Infineon’s multimedia platform enables mobile phone multimedia functionality, such as video streaming, video recording and playback, and true location-based services.

At the 3GSM 2004 show in Cannes, France, Infineon demonstrated the capability of its multimedia platform to handle UMTS, EDGE and GPRS networks as well as Assisted-GPS (A-GPS) making possible location-based services.

March 19, 2004. Alcatel announced general availability of the Alcatel 8607 A-GPS (Assisted-GPS) Positioning Server for GSM Networks. By providing A-GPS capabilities, the Alcatel 8607 Positioning Server supports the mass-market adoption and success of advanced high-accuracy Location Based Services (LBS).

Building on the existing relationship with Qualcomm, Alcatel is the first mobile solutions vendor to provide a proven and commercially ready A-GPS location server solution for GSM that is compatible with Qualcomm’s location solutions. This collaboration positions both companies as market leaders in A-GPS to implement new Open Mobile Alliance (OMA) LBS standards activities associated with A-GPS technologies.

April 26, 2004. Trimble and u-Nav Microelectronics Corp. announced they have forged an alliance to jointly develop and market integrated global positioning system (GPS) chipsets and software solutions to incorporate Trimble’s GPS software and u-Nav’s low-power GPS chipsets for use in portable electronic devices.

Trimble core GPS software provides both stand-alone and assisted-GPS (A-GPS) operation and includes the company’s tightly integrated Kalman Filter that supports Trimble’s optional sensor assisted (dead reckoning) algorithms.

u-Nav’s patented semiconductor platform is based on an all CMOS design and features a filter search (acquisition) engine, combined with a tracking engine to enable small and low-cost GPS architecture for devices such as cellular handsets, PDAs, watches and other portable electronic devices.
u-Nav’s technology delivers ultra-low power at low cost with state of the art performance to enable operation indoors and in urban canyons.

Assisted-GPS in use today (May, 2004)

In April 2001, SECOM Co., Ltd., the largest security company in Japan, launched Coco SECOM, a nation-wide location-based security service. This service uses gpsOne technology. The Coco SECOM service uses a small tracking device, allowing users to easily locate a child, friend, or other loved one who is carrying the device. The service has been made available on a range of KDDI mobile phones more recently.

NATE Drive is a position location service that allows motorists to find their location and enables them to better navigate traffic with voice instructions and graphics. SK Telecom launched "NATE Drive" gpsOne enabled services on July 30, 2002. Associated applications include: Landmark Information, Route Guide, My Drive, Utilities, Traffic Information and Emergency.

On January 15, 2004, Hutch launched a location based service under the brand name "Navi". Hutch's service integrates Qualcomm's A-GPS, gpsOne and a solution developed in conjunction with Navitime from Japan. There are five Navi services including "Where are you", "Where am I", "MapSearch", "CarNavi", "Nearestplace", and includes built-in privacy control feature which can be set by the user to provide complete protection from unsolicited "where are you?" searches.

KDDI offers one of the most successful location based services worldwide. Called EZnavigation, the service uses gpsOne technology and allows users to take advantage of the latest emergency services, child finder services, detailed maps with directions, and many other location applications, both consumer and enterprise-oriented. Models compatible with eznavigation can, from EZ Web sites, display a precise map showing the user's current location and desired destination. Highly accurate positional information can be obtained based on signals from GPS satellites and cellular base stations. To date KDDI has offered 130 unique applications taking advantage of gpsOne position location information.

U-Map is a position location service that provides China Unicom subscribers with access to information and services based on their proximity, including traffic, entertainment and emergency services. U-Map utilizes gpsOne position location technology which provides accuracy to within 5 meters, both indoors and outdoors, wherever there is CDMA2000 1X network coverage.

Remark: Most of the GPS phones on our GPS phones page are A-GPS phones. However, they can only use the "assistance" if the network on which they are used, offers this technology. Nextel offers it for the Motorola iDEN phones and others probably offer the service too. It seems that network operators do not yet want to talk about A-GPS, so it is difficult to find out exactly which phone is assisted on which network.

And Garmin and Magellan?

We do not know their secret R&D programs.

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