LBS Description

The Broadcom LBS facility augments GPS aiding and positioning.

Introduction

This document provides a description of the programming interface for Broadcom's LBS Client. The LBS Client is software for mobile devices to enable the best possible location performance, using GPS and other wireless capabilities of the device.

As shown in Figure 1, the LBS Client receives data from an LBS Server to enable best possible location performance and also reports data back through the LBS Server to an LBS Database for future use by other LBS Client-equipped devices. The three entities acting in concert with one another form the LBS System.

The LBS Client enables near-100% worldwide location yield, including in deep urban indoor environments; time-to-fix of several seconds or less and accuracy of 100m or better (subject to availability of wireless signals). The LBS Client is designed to:

  • Provide the best possible reference location for AGNSS (GPS, GLONASS, Galileo etc. satellites) or use terrestrial RF nodes (cellular, WiFi, FM) alone for location, as environment and device capabilities make feasible
  • Detect, capture and report back RF data into Broadcom's WorldWide Reference Database (WWRD). The WWRD the world's most comprehensive location database
  • Partition portions of the WWRD into local reference DBs for delivery to devices
  • Use multiple RF nodes to compute location more precisely than nearest node (e.g., Cell ID) or nearest nodes (e.g., fingerprinting) approaches
  • Determine & receive assist data and local reference DBs needed from an LBS Server
  • Determine position without going back to an LBS Server for extended time (weeks)
lbs_cycle.gif

Figure 1.

The three parts of the LBS System, LBS Client, LBS Server and the LBS Database operate together to enable seemless wireless location capabilities. By continuously updating the estimates of the worldwide RF environment the system ensures the highest availability of accurate reference data.

LBS can provide complete solution for providing assistance data

In addition to serving as a source of data for the LBS Client to compute the mobile location, the LBS System, having a complete set of worldwide RF reference locations can directly serve clients with the locations of the local nodes. This provides another interface, in addition to AGPS and SUPL, for cell id location information and allows for additional flexibility in implementation on the mobile device.

db_server_interface.gif

Figure 2.

Certain implementations may benefit by this alternate approach in addition to, or instead of the SUPL or AGPS interfaces.

Cell ID database benefits SUPL server

The Broadcom SUPL server provides AGPS assistance data and can retrieve location data over a mobile datalink. As wireless networks change, update and migrate, their system characteristics change and this information can be automatically reported by the LBS Client interface. In turn, assistance data can be updated and improved as more and more observations are added by mobile clients. This is achieved by: 1. The Broadcom LBS enabled handset collects information about Cell IDs (2G or 3G) that can be seen by a mobile deviceand sends this information periodically to the Broadcom LBS server (Figure 3 3) 2. The Broadcom SUPL server uses the Cell ID database to provide a reference location to the SUPL Enabled Terminal (SET). (Figure 3 3)

db_supl_interface.gif

Figure 3.

SUPL Network Initiated (NI) Call Flow from Location application prospective

The diagram below indicates the interactions between GPS task and location application.

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