Requirements of a C-CDMA Pseudolite Indoor Geolocation System

Ilir F. Progri, William R. Michalson, Jinling Wang, Matthew C. Bromberg, and James Duckworth

Abstract:	The paper provides the requirements for building (or designing) a C-CDMA pseudolite indoor geolocation system. A C-CDMA pseudolite indoor geolocation system consists of four C-CDMA pseudolites and one or more C-CDMA receivers. The purpose of this paper is to provide the requirements for building C-CDMA pseudolites and a C-CDMA receiver. First, the pseudolite is assumed stationary and the geolocation information consists of the transmitter position and time. For each pseudolite this information is 4-ary encoded data at a symbol rate of 1 KHz. For example, an encoded geolocation signal is spread using a Kasami sequence which runs at a rate of 1.023 MHz and then the signal is modulated on [10 15 20 25] MHz carrier signals each one of which corresponds to each of pseudolite respectively via a QPSK modulator to resist interference encountered in an indoor geolocation environment. A total of 4 pseudolites are simulated to enable a geolocation solution for the receiver. The spreading modulation is that of a VBOC(2,1, alpha) which we have examined previously to provide a better spectrum utilization than the BOC(2,1) and definitely much better than the PSK. Second, the receiver consists of four channels each one of which is assigned to a single transmitter. On each receiving channel the received signal is down-converted, de-spread using the Kasami sequence, demodulated and decoded. Third, the channel consists of the following models: (1) a realistic indoor path loss, (2) realistic Rayleigh and Rician fading channels, (3) receiver thermal noise, (4) phase frequency offset, and (5) additive white Gaussian noise. The system will include the ability to perform distance measurement; to take into consideration the effect of transmitter clock stability on position accuracy; such effects will include the transmitter and receiver oscillator drift (short term stability) on positioning accuracy; the signal processing on the receiver design will include techniques for detecting an extremely week LOS signal and for maintaining lock on the LOS signal in the presence of severe multipath. It is expected that this paper will provide the required overview for first designing the system components utilizing as much as possible commercial of the shelf components and provide the framework for Giftet Software solution products one of which is a global software solutions for a C-CDMA pseudolite indoor geolocation system to operate under heavy multipath and low signal to noise ratio environment. Simulation results in MATLAB and Simulink are provided.
Published in:	Proceedings of the 63rd Annual Meeting of The Institute of Navigation (2007) April 23 - 25, 2007 Royal Sonesta Hotel Cambridge, MA
Pages:	654 - 658
Cite this article:	Progri, Ilir F., Michalson, William R., Wang, Jinling, Bromberg, Matthew C., Duckworth, James, "Requirements of a C-CDMA Pseudolite Indoor Geolocation System," Proceedings of the 63rd Annual Meeting of The Institute of Navigation (2007), Cambridge, MA, April 2007, pp. 654-658.
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