Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references: p. 94-95.Issued also on microfiche from Lange Micrographics.This work addresses the problem of rapid carrier-phase acquisition for QAM constellations, and specifically for the 32-QAM, 64-QAM, 128-QAM, and 256-QAM constellations, operating over an AWGN channel. It is assumed that there is no frequency or symbol timing error. Seven algorithms in all are derived and tested. The first is the maximum-likelihood (ML) estimator, which is found to be accurate but impractical to implement. A suboptimal ML type estimator is derived from the ML algorithm and is found to be simpler but still impractical. The power-law (PL) estimator is derived as the low SNR limit of the ML estimator, and is found to be very simple, but having poor error performance. A threshold is added to the PL algorithm and the performance is improved, but not enough for rapid phase acquisition for most cases. An algorithm is derived specifically for use on the cross constellations which further improves performance, but this algorithm is superseded by an estimator based on a trellis structure and the Viterbi Algorithm which is developed. Finally a suboptimal version of the trellis algorithm is developed which reduces the complexity of the trellis algorithm by two-thirds. Both the trellis and the suboptimal trellis algorithm perform well enough for phase acquisition and are simple and practical to implement
