New Results on Symbol Rate Estimation in Digital Satellite Receivers

摘要

Estimator algorithms for transmission parameters like carrier frequency and phase or symbol timing have already reached a mature state, which is also confirmed by a nearly infinite number of papers available from the open literature. However, when it comes to the recovery of the symbol rate, the situation is somewhat different with much less information published so far. A major reason for this is the fact that the symbol rate is typically known to the receiver station and little deviations from the nominal value do not really affect the performance, at least in burst-mode systems with smaller packet sizes. But this assumption does not hold true in a non-cooperative environment or when data are transmitted continuously; for this kind of scenarios, it might be mandatory to estimate and correct the symbol rate by a powerful algorithm. In the current paper, we introduce a data-aided and carrier-blind method for joint estimation of symbol timing and symbol period, which is based on the evaluation of a two-dimensional correlation procedure. In order to reduce the computational load, the timing and rate axes are discretized appropriately, whereas values in between are addressed by an interpolative process. In addition, the modified Cramer-Rao lower bound (MCRLB) is derived as the theoretical limit of the jitter performance. In case of a negligible frequency offset, it is shown by numerical results that the jitter variance is close to the MCRLB, otherwise it is suggested that the observation window is partitioned suitably with each partition subject to the developed algorithm.