Wireless Infrastructure

Detecting False Signals with Automatic Gain Control

April 1, 2012By
FIGURE 6. Google Earth view of testing environment.

A component of most GPS receiver front-ends, the automatic gain control (AGC) can flag potential jamming and spoofing attacks. The detection method is simple to implement and accessible to most GPS receivers. It may be used alone or as a complement other anti-spoofing architectures. This article presents results from a baseline AGC characterization, develos a simple spoofing detection method, and demonstrate the results of that method on receiver data gathered in the presence of a live spoofing attack. read more

Calculating Time-to-First-Fix

November 1, 2011By
Figure 5. Indoors signal strength (C/N0) for satellite PRN09. Each colored curve represents the signal strength measured on a different day, starting at the same orbital time.

Cell-phone users are often more concerned about the speed of positioning than the accuracy, making time-to-first-fix the most important factor in a GNSS mass-market receiver’s perceived performance. However, TTFF is generally difficult to characterize and optimize because of the need to encompass a wide range of environments, including indoors. read more

This article is tagged with and posted in Indoor Positioning, Wireless Infrastructure

Expert Advice: Exploring the Technologies Behind Location-Gate

September 1, 2011By

For the past several months, controversy has raged over the revelation that Apple and Google tracked mobile subscriber location movements and stored that information in an unencrypted file on the handset, where it was potentially vulnerable to hacking and other inappropriate usage. The resulting Location-gate scandal highlights the sometimes tenuous control of mobile subscriber information versus the business objectives of dominant platform and applications providers. These business objectives may include immediate revenue opportunities from the subscriber being tracked or broader self-interest initiatives, such as collecting marketing data that may be valuable to third parties like advertisers, or building subscriber-reported Wi-Fi access point databases. read more

EGNOS Gets to Work

February 1, 2011By
Figure 6. Time series of horizontal positioning errors for stand-alone GPS, conventional EGNOS, and position domain EGNOS solutions at HUEG IGS station.

GPS corrections from the European Geostationary Navigation Overlay Service can improve the positioning accuracy and user experience of GPS-enabled mobile phones, even if EGNOS satellites are not visible and even when the GNSS chipset in the phone does not support satellite-based augmentation systems. read more

This article is tagged with , and posted in Augmentation & Assistance, Mobile Devices, Wireless Infrastructure

Single-Shot Position: Cell-Phone Location without Ephemeris

February 1, 2011By
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A new method enables the mobile phone to compute its own position using acquisition assistance data with increased resolution in some of the fields. It benefits network operators as they can deliver the best performance with minimum bandwidth requirements, making this especially relevant in emergency-call situations. read more

This article is tagged with , and posted in Mobile Devices, Wireless Infrastructure

J911: Fast Jammer Detection and Location Using Cell-Phone Crowd-Sourcings

November 1, 2010By
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Inexpensive, readily available GPS jammers constitute a threat to safety, national infrastructure, and industry revenue streams. Cell phones could incorporate GPS jam-to-noise (J/N) ratio detectors to provide timely interference detection and effective localization, with a flexible and updateable system since the crowd processing function resides in software. read more

This article is tagged with , and posted in Wireless Infrastructure