A comparison of VLSI architectures for time and transform domain decoding of Reed-Solomon codes

It is well known that the Euclidean algorithm or its equivalent, continued fractions, can be used to find the error locator polynomial needed to decode a Reed-Solomon (RS) code. It is shown that this algorithm can be used for both time and transform domain decoding by replacing its initial conditions with the Forney syndromes and the erasure locator polynomial. By this means both the errata locator polynomial and the errate evaluator polynomial can be obtained with the Euclidean algorithm. With these ideas, both time and transform domain Reed-Solomon decoders for correcting errors and erasures are simplified and compared. As a consequence, the architectures of Reed-Solomon decoders for correcting both errors and erasures can be made more modular, regular, simple, and naturally suitable for VLSI implementation

Adaptive Carrier Tracking for Direct-To-Earth Mars Communications

We propose a robust and low complexity scheme to estimate and track carrier frequency from signals traveling under low SNR conditions in highly non-stationary channels. These scenarios arise in planetary exploration missions subject to high dynamics, such as the Mars exploration rover missions. The method comprises a bank of adaptive linear predictors supervised by a convex combiner that dynamically aggregates the individual predictors. The adaptive combination is able to outperform the best individual estimator in the set, leading to a universal scheme for frequency estimation and tracking

Order-adaptive frequency trackers for direct-to-Earth Mars communications

During the entry, descent and landing phase (EDL) of the missions to Mars, the spacecraft's high dynamics imprints severe Doppler swings on the signals transmitted via the direct-to-Earth (DTE) channel. In order to recover the data that record the mission status from the received signal, a reliable estimate of the Doppler profile is required. We extend previous work by developing order-adaptive schemes that enforce frequency continuity and improve tracking performance and, as a result, the overall frequency mean-square error as well

Efficient Adaptive Carrier Tracking for Mars to Earth Communications During Entry, Descent and Landing

In the Mars rover missions the signals transmitted back to Earth travel under low SNR conditions in highly non-stationary channels [1, 2]. During the entry, descent and landing phase (EDL), the spacecraft high dynamics yields severe Doppler effects. We propose a robust and low complexity scheme to estimate and track carrier frequency from the received signals at the Earth end. The method employs a hierarchical arrangement of convex linear prediction cells that is dynamically adapted to respond to the channel conditions. The adaptive combination is able to outperform the best individual estimator in the set, leading to a universal scheme for frequency estimation and tracking. In order to compensate the lag error effect, we explore an efficient forward and backward aggregation scheme that improves considerably the frequency RMS error as compared to the original method [3]