Modeling and Analysis of Discrete-Time DLL Tracking for Quadrature-Spread CDMA Signals over Rayleigh Fading Channels
Hamood-ur-Rehman Khan, Mohamed Adnan Landolsi
Signals and Telecommunication Journal, Vol. 2, No. 1, 2013.
DOI: 
Link: http://www.dline.info/stj/fulltext/v2n1/5.pdf
Abstract:
The paper addresses the modeling and performance analysis of discrete delay-locked loop (DLL) code tracking for quadrature-spread direct-sequence code division multiple access (CDMA) signals (used in 3G UMTS) over Rayleigh fading channels. A discrete-time stochastic difference equation is derived to model the DLL tracking error dynamics as a firstorder Markovian process. The stationary probability density function of the tracking error is derivediteratively by solving a Kolmogorov-Chapman integral equation. Numerical examples with different system loading assumptions show that the proposed technique, while having a moderate computational complexity, produces much more accurate results when compared to simplified approximations based on Gaussian models for the DLL tracking error.