Pull-in capability of a modified code tracking loop for direct-sequence spread-spectrum communication on a frequency-selective fading channel

The pull-in capability of a modified code tracking loop (MCTL) for direct-sequence spread-spectrum communication is investigated on a frequency-selective fading channel. By taking advantage of the inherent diversity, the modified code tracking loop is embedded into a RAKE receiver to avoid the problem of drift and flutter of error signals caused by multipath interference; thus, a robust pull-in capability can be provided. Furthermore, a multipath interference regeneration and cancellation technique is also proposed to improve the error characteristics of the proposed technique. Analytical expressions of the error characteristics are derived and then confirmed by means of extensive computer simulation results. Very attractive behaviors obtained using the proposed technique are verified.