Noncoherent DLL and TDL PN code tracking loops in Rayleigh fading channels

In addition to PN code acquisition, PN code tracking is an important issue in direct sequence spread spectrum communication which is popular in personal communications and cellular communications. Tracking performance to maintain reliable continuous communications in multipath fading channels has not been carefully investigated. The authors analyze the noncoherent delay locked loop and tau dither loop in the two-ray Rayleigh fading channels. With numerical results, the authors observe that the mean time to lose lock is generally increased in strong fading compared with the AWGN case. However, such fading results in the degradation of tracking error performance, which may have very significant impacts in certain circumstances, especially the second ray being comparable with the first ray