Implementation aspects for noncoherent tracking based on a time-discrete delay-locked loop

A direct sequence spread spectrum receiver with a square root raised cosine chip-matched filter (CMF) and a noncoherent early-late (NCEL) time-discrete delay-locked loop (DLL) is analyzed. The receiver is studied in regard of the chip over-sampling factor λ and of parameters relating the CMF. The NCEL discriminator´s S-curve is derived and used in a linearized loop model from which the DLL´s tracking performance is analyzed. The bit error rate simulations in which λ and CMF parameters are varied, can then be done using DLLs which theoretically all have the same tracking capabilities. The results show performance degradations between 0.1 and 0.95 dB for different λ and CMFs when compared to ideal detection