Direct-sequence spread-spectrum chip tracking in the presence of unresolvable multipath components

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.