KEYWORDS: Global Positioning System, Receivers, Satellites, Data communications, Standards development, Global system for mobile communications, Doppler effect, LabVIEW, Networks, Wireless communications
During recent years, location technologies have emerged as a research area with many possible applications in wireless
communications, surveillance, military equipment, etc. Location Based Services (LBS) such as safety applications have
become very popular. For example, US Federal Communication Commission Enhanced 911 (E911) Mandate seeks to
provide emergency services personnel with location information that will enable them to dispatch assistance to wireless
911 callers much more quickly. Assisted GPS (A-GPS) is an extension of the conventional Global Positioning System
(GPS) which increases start-up sensitivity by as much as 25dB relative to conventional GPS and reduces start times to
less than six seconds. In A-GPS assistance data is delivered to the receiver through communication links. This paper
addresses the generation of the assistance for GPS simulators for testing A-GPS receivers. The proposed approach is to
use IP-based links and location support standards for assistance delivery avoiding network-specific signaling
mechanisms so that GPS receiver developers can use this information for testing A-GPS capabilities using basic GPS
simulators. The approach is implemented for the GPS simulator developed by the National InstrumentsTM.
KEYWORDS: Received signal strength, Legal, Databases, Computer intrusion detection, Network security, Local area networks, Algorithm development, Detection and tracking algorithms, Standards development, Error analysis
WLAN networks are widely deployed and can be used for testbed and application developments in academic
environments. This paper presents wireless positioning testbed and a related application implementation methodology as
a case study. Nowadays state-of-the-art WLAN positioning systems achieve high location estimation accuracy. In
designated areas the signal profile map can be designed and used for such a positioning. Coverage of WLAN networks is
typically wider than the authorized areas and there might be network intrusion attempts from the vicinity areas such as
parking lots, cafeterias, etc. In addition to conventional verification and authorization methods, the network can locate
the user, verify if his location is in the authorized area and apply additional checks to find the violators.
KEYWORDS: Receivers, Optical correlators, Modulation, Signal processing, Global Positioning System, Digital signal processing, Convolution, Satellites, Fourier transforms, Demodulation
Most of the current wireless communication devices use embedded processors for performing different tasks such as physical layer signal processing and multimedia applications. Embedded processors provide a reasonable trade-off between application specific implementation and hardware sharing by different algorithms for more optimal design and flexibility. At the same time the widespread popularity of these processors drives the development of algorithms specifically tailored for embedded environments. Fast Fourier Transform (FFT) is a universal tool, which has found many applications in communications and many application specific architectures and Digital Signal Processor (DSP) implementations are available for FFT. In this paper our focus is in embedded algorithms for spread spectrum communication receivers, which are using FFT as an engine to compute convolutions. Using FFT-based correlators one can search over all possible so-called code phases of direct sequence spread spectrum (DS-SS) signal in parallel with fewer operations than conventional correlators do. However in many real-life scenarios the receiver is provided with a timing assistance which confines the uncertainty in code phase within a limited area. The FFT based search is becoming redundant and a reasonable strategy is to modify the FFT based methods for better utilization of embedded processor resources. In this paper we suggest a reduced complexity frequency domain convolution approach for the search over limited number of code phases.
Conference Committee Involvement (4)
Multimedia on Mobile Devices 2013
4 February 2013 | Burlingame, California, United States
Multimedia on Mobile Devices 2012
25 January 2012 | Burlingame, California, United States
Multimedia on Mobile Devices 2011
25 January 2011 | San Francisco Airport, California, United States
Multimedia on Mobile Devices 2010
18 January 2010 | San Jose, California, United States
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