The Siemens Communications Group will be one of the first companies to bring a standardized solution for Assisted Global Positioning Systems (A-GPS) to the market: The so-called Secure User Plane Location (SUPL) standard is being developed by the Open Mobile Alliance (OMA) and is scheduled for release in June 2005. While current proprietary A-GPS systems work only with devices from specific manufacturers, the OMA standard will enable the positioning service to be used on any A-GPS-capable phone on any mobile network. Siemens is already conducting interoperability tests with A-GPS chipset suppliers Global Locate and SiRF Technology Holdings and with device manufacturers Compal Communication (CCI) and HP. The SUPL-based Siemens A-GPS solution will be offered to mobile operators as of the third quarter of 2005.
Current A-GPS solutions are based on the so-called control plane architecture, which requires extensive modifications of the mobile network infrastructure in line with the 3GPP location services standards. In contrast, SUPL-based A-GPS systems employ a "user plane" architecture. In this design, a location server, which communicates directly with the mobile device via an IP (Internet Protocol) link, is integrated into the mobile communication network. Core and radio networks remain unchanged. SUPL is therefore the solution of choice for operators looking to be able to offer first A-GPS applications quickly and cost-effectively. The more complex control plane architecture, on the other hand, is better suited for operators counting on high number of users right from the start or planning to offer applications with very short response times, such as emergency calls. Since operators can convert from user plane to control plane with the same network components, they can now test the market for A-GPS with a low-cost infrastructure and expand it later. With the addition of its new SUPL-based A-GPS solution, Siemens now carries both architectures in its portfolio.
"Thanks to the Open Mobile Alliance's SUPL standard, mobile devices from different manufacturers are now able to exchange A-GPS data with all mobile communication networks," explains Christoph Caselitz, President of Mobile Networks at Siemens Communications. "This interoperability is essential if A-GPS services are to be successful in the market and therefore forms the basis for a future-proof A-GPS architecture on the operator's network. That's why Siemens pushed for this standardization in the OMA and is now the first company offering to carry out interoperability tests of our SUPL-based solution with A-GPS chip and mobile device manufacturers."
"As the only company exclusively focused on end-to-end assisted GPS, Global Locate is extremely pleased to demonstrate its industry-leading performance while proving the efficacy of the SUPL architecture," said Chris Lane, Business Development Director of Global Locate. "We are confident that such interoperability testing will lead to commercially available terminals by the end of 2005."
A-GPS architecture: User Plane versus Control Plane
A "user plane" solution is an A-GPS system where communication between server and mobile device runs over a normal data connection, for example GPRS. The corresponding standard defined by the OMA is called SUPL. Integrating a user plane solution takes advantage of protocols and interfaces that already exist in the core and radio networks. When A-GPS is designed as a "control plane" solution, servers and mobile devices communicate via signaling channels on the core and radio networks. This requires the provision of appropriate interfaces and protocols across the entire network. The corresponding LCS (Location Services) standard was developed by 3GPP (3rd Generation Partnership Project).
To determine a user's precise location, traditional positioning technology based on the Global Positioning System (GPS) requires visual contact to special satellites circling the earth in geostationary orbits at an altitude of approximately 20,000 kilometers (12,000 miles). To determine the position, a locating device must receive the signals from at least three of these satellites. With a traditional GPS receiver it can sometimes take several minutes to collect all the satellite navigation data and compute the precise location. In addition, in areas with many tall buildings, the satellites' signals are often so weak that GPS does not work reliably. With A-GPS, the mobile device receives information about the satellites' orbit, frequencies and functionality over the wireless network. As a result, it can detect and analyze even weak satellite signals at lightning speed. The A-GPS technology uses the radio link between base station and mobile devices to transmit this "assisted" satellite data within a matter of seconds, thus saving time and battery power compared to traditional GPS systems. Even under difficult reception conditions, it takes the unit only a few seconds rather than minutes to display the correct coordinates. Since Assisted GPS also works in enclosed spaces, it even makes mobile phone-guided virtual city and museum tours and other indoor applications possible. A user can also use his mobile phone to find his way from place to place in unfamiliar cities. And after car accidents, the A-GPS solution can quickly transmit the vehicle's precise location to an emergency dispatch center so that help reaches injured persons more quickly.