Title :
Direct-sequence spread-spectrum chip tracking in the presence of unresolvable multipath components
Author :
De Gaudenzi, Riccardo
Author_Institution :
Qualcomm Inc., San Diego, CA, USA
fDate :
9/1/1999 12:00:00 AM
Abstract :
Delay lock loop (DLL) chip time tracking in the presence of unresolvable multipath components is known to be suboptimum and prone to tracking errors. In the present contribution, the behavior of noncoherent and coherent digital DLL (DDLL) for a bandlimited direct-sequence spread-spectrum (DS-SS) system in the presence of multipath is analyzed under slow and fast fading assumptions. Due to the fading channel random nature, the tracker performance is evaluated according to a statistical metric. Numerical results show that the noncoherent DLL outperforms the coherent DLL in terms of demodulator losses caused by unresolvable multipath
Keywords :
bandlimited communication; delay lock loops; demodulators; fading channels; mobile radio; multipath channels; radio tracking; random processes; signal detection; spread spectrum communication; statistical analysis; DLL chip time tracking; Globalstar; bandlimited DS-SS system; coherent detector; coherent digital DLL; delay lock loop; demodulator losses; direct-sequence spread-spectrum chip tracking; fast fading; forward link CDMA air interface specification; noncoherent digital DLL; random fading channel; slow fading; statistical metric; tracker performance; tracking errors; unresolvable multipath components; Baseband; Demodulation; Fading; Finite impulse response filter; Frequency; Multiaccess communication; Multipath channels; Space technology; Spread spectrum communication; Tracking loops;
Journal_Title :
Vehicular Technology, IEEE Transactions on
