GeoLENs™ UMTS/WCDMA System Features

GMLC (Gateway Mobile Location Center)

• Controls and authenticates requests for a subscriber’s location from applications
• Coordinates transformation of position    information into latitude and longitude that is handed off to an application or PSAP
• Interfaces to MSC and HLR to query for Cell ID positioning, allowing for cost-effective low  accuracy solution
• Interfaces to Public Safety Answering Points (PSAPs) or other Emergency/Public Safety Authorities for E911, E112, etc.
• Supports standards-based interfaces

                - 3GPP/GSM Le interface

                - Mobile Location Protocol (MLP) for location services and European

                  E112 emergency  interface

                - J-STD-036 for E911 Phase 2 in the U.S.

• Can be combined with SMLC, SAS, SLP, etc. on single equipment platform

SAS (Stand-Alone SMLC):

• Supports UMTS/WCDMA networks
• Control Plane Location (CoPL)
• Hybrid, A-GPS, RTT, Cell/Sector ID Locating Methods
• Interfaces to A-GPS Reference Network data feed for assistance data
• Interfaces with RNCs to provide A-GPS assistance data to the UE
• Supports UE-Assist and UE-based A-GPS
• Can be combined with GMLC, SMLC, SLP, etc. on single equipment platform

GeoLENs™ UMTS/WCDMA Locating Methods:

UMTS Assisted GPS (A-GPS)

WCDMA A-GPS Hybrid Location

Assisted-GPS (A-GPS) is a handset-based mobile locating method fundamentally based on GPS locating technology but functionally distributed between the mobile and a centralized server. Mobiles must be specially equipped to receive GPS signals from multiple GPS satellites in order to make measurements of the signals from GPS satellites and relay this information or their calculated position through the mobile network to the SMLC/SAS/SLP software (iSAS: Control Plane, SUPL: User Plane implementations). In cases where the mobile does not compute its own location from GPS data, the SMLC/SAS/SLP uses GPS data relayed from the target mobile to compute the mobile's position. Once determined, the position can be sent to a gateway mobile location center (GMLC) or SUPL Location Platform (SLP) for distribution to the application that originated the location request. A-GPS is a supplemental form of GPS whereby GPS satellite position data is sent from the SMLC/SAS/SLP through the mobile network to the mobile to assist the mobile in determining which GPS satellites it should attempt to acquire. This supplemental data is intended to:

• Speed the mobile's satellite signal acquisition process.
• Increase the mobile's ability to receive signals from the target GPS satellites.

A-GPS is intended to reduce latency and improve other location performance when a mobile's view of GPS satellites is obscured. That can occur when the caller is in a building, in a vehicle, or in an "urban canyon." Although A-GPS does improve overall locating performance, accuracy, latency, and yield performance can be subject to degradation if a mobile's view of GPS satellites is obscured.

Round Trip Timing Positioning

RTT Positioning

Round Trip Time (RTT) is a control plane mechanism whereby the node-B measures the signal propagation distance between the mobile and the base station.  It accomplishes this by utilizing a known downlink message transmit time from the node-B, measuring the corresponding uplink acknowledgement from the mobile, and subtracting off the message receive/transmit delay within the mobile.  This produces the round trip (two-way) signal delay, half of which can be used to compute the distance the signal travels between the mobile and the base station.  This RTT distance results in a circular ring around the base station representing  mobile location possibilities.  If the mobile is in a region where multiple base stations can communicate with the mobile, multiple RTT measurements can be computed and the intersection of multiple rings represents the mobile location.

Cell ID Positioning

Allows basic location services to be deployed using existing handsets and network capabilities and kick start market interest and revenues.

• Cell sector location coordinates passed to the application
• Can be accomplished using a standalone Gateway Mobile Location Center (GMLC) that connects to MSC and HLR using ATI
• SMLC based when deployed
• Can be configured to provide mid point of the cell if desired

Uplink Time Difference of Arrival—U-TDOA

UTDOA 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 Location Measurement Units (LMUs) .  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.

 LMUs may also be equipped with antennae capable of providing angle of arrival measurements (AoA) which can augment timing measurements where coverage or DOP is poor.

User Plane Location (SUPL) Solutions

For User Plane (SUPL) location in GSM networks, please refer to Andrew’s SUPL Location Platform (SLP).