A study on a fast tracking coherent detection for mobile radio communications

摘要

In future high hit-rate mobile radio communications, baseband modulation signals corresponding to both each subcarrier of OFDM and spreading code of multi-code DS-CDMA will be, in many cases, narrow-band ones. In these systems, since the RF frequency band is expected to become much higher, degradations due to both the fading fluctuation and the carrier frequency offset become much severer. For the purpose of solving these problems, this paper investigates a fast tracking coherent detection scheme that conducts both linear prediction of the carrier signal, and the sequence estimation based on the linear prediction estimation errors, employing the Viterbi algorithm. Computer simulations show that the irreducible error rate due to the fading fluctuation can be removed if the order of the linear prediction is equal to or larger than the number of the multi-paths. Furthermore, it is demonstrated that the degradation due to the carrier frequency offset can be completely eliminated.