Extending the significance of the GeoLENs portfolio is the announcement of location information server (LIS) products supporting the new generation of IP Location protocols and applications defined by the Internet Engineering Task Force (IETF). The LIS range supports the HTTP Enabled Location Delivery (HELD) protocol, which will allow every form of broadband IP network to be location-enabled. Intended for use with every kind of Internet application, including presence services, Web services, and device-based applications, the IETF protocols are also fundamental to the support of next-generation emergency service architectures such as NENA i3 and IETF ECRIT.

The LIS range spans more than mobile networks. It’s also applicable to wireline networks such as DSL, cable, and FTTx. The GeoLENs broadband provider LIS is designed to support all access technologies, delivering the power of IP Location to wireline, WiMAX, and enterprise networks. To permit 3G network operators to leverage their existing investment in location infrastructure, the GeoLENs 3G Bridge LIS supports the semantic capabilities of HELD on the client side while invoking the power of the established location infrastructure on the network side. For ISP operators and infrastructure wholesalers, the GeoLENs ISP LIS supports the necessary LIS-to-LIS communication that extends the retail-wholesale model of broadband to the location service itself.

Complete Location Platform For Wireless And Wireline

With GeoLENs, Andrews offers a complete hybrid platform for integrating location technologies and techniques for both wireless and wireline networks. The GeoLENs family comprises the GeoLENs MLC and the GeoLENs LIS.

• The GeoLENs MLC can location-enable wireless networks of all kinds for applications such as E911 and E112, commercial location-based services, and security. As no single wireless location technique can meet the needs of all location-enhanced applications, the MLC system bridges the gap between location-enhanced services and the location technologies that enable them by providing the capability to implement any or all wireless locating techniques.

Also, the MLC supports handset-based, network-based, and hybrid locating technologies—cell identity, A-GPS, E-CID, U-TDOA on the traffic channel, MREL, and angle of arrival (AOA)—individually or in combination, on a common platform (Fig. 1). GeoLENs gives operators the flexibility to add or refocus their location system as their needs change and as market directions clarify.

The GeoLENs LIS can location-enable IP-based networks to support all location-sensitive applications. It can be deployed in access networks such as enterprise, DSL, cable, and other wired and wireless broadband access types to provide the location of any device connected to an IP network.

How The New Technology Works

U-TDOA takes timing measurements of standard handset RF procedures (uplink). It calculates the difference in the time of arrival of the RF signal between multiple pairs of LMUs. The differences in arrival time determine hyperbolic curves between receivers where the phone could be. The location is then estimated by the best intersection of the multiple hyperbolic curves (Fig. 2). LMUs may also be equipped with antennas capable of providing AoA measurements, which can augment timing measurements where coverage is poor.

MREL is the next generation of location technology used with Andrews’ LMUs. U-TDOA and MREL use different techniques to determine a phone’s location. MREL exploits features in the newer digital signaling protocols to produce location results in areas U-TDOA cannot. For example, MREL requires only two sensor sites instead of U-TDOA’s three, which is particularly important in rural or highway corridors where only two sensor sites might be available.

MREL makes innovative use of the feedback loop that exists between a mobile and a basestation to determine the actual time that the phone transmits a signal of interest. MREL then uses the transmission time and the time of arrival of the signal at a sensor site to determine a circular range ring, where the mobile could be located, around each sensor site. The location is then estimated by the best intersection of the multiple range-rings (Fig. 3).

Conversely, U-TDOA calculates the difference in the time of arrival of the mobile signal between multiple pairs of receivers. The differences in arrival time determine hyperbolic curves between receivers of where the mobile could be. The location is then estimated by the best intersection of the multiple hyperbolic curves.

Unlike U-TDOA, MREL does not depend on the time differences of arrival of a signal at multiple sensor sites. It uses absolute times of transmission and arrival. Because MREL does not rely on differences, it can generate a range ring for each sensor site and accurate location information with just two sensor sites. U-TDOA cannot generate accurate location information with anything less than three sensor sites.

Testing shows that in a comprehensive set of environments, MREL offers a high accuracy location capability in areas where A-GPS and U-TDOA may fail. Coupled with the other location technologies available in GeoLENs, MREL provides the most comprehensive and competitive location solution on the market today, both for LBS and E911 applications.

Andrews Solutions