Feedback-free method for the demodulation of higher-level MQAM signals without knowledge of the transmitted symbols
AssigneeRohde & Schwarz GmbH & Co. KG
InventorKurt Schmidt
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Abstract
For demodulation of higher-level MQAM signals without knowledge of the transmitted symbols, the clock phase error is calculated first after the sampling of the baseband signal with a clock frequency corresponding to the MQAM signal, and the corresponding time shift of the baseband signal is compensated therewith by interpolation (clock synchronization). Subsequently, the carrier frequency deviation and the carrier phase deviation are calculated feedback-free according to the principle of the maximum likelihood theory using Fourier transformation or by convolution in the time domain, and thus the data sequence is compensated.
Claims6
A method for demodulating higher-level MQAM signals produced by transmitting symbols in a data sequence using a baseband signal, without knowledge of the transmitted symbols, comprising:
- (a) by sampling the baseband signal with a clock frequency corresponding to the MQAM signal;
- (b) estimating a clock phase error and compensating a corresponding time shift of the baseband signal by interpolation with the estimated clock phase error;
- and
- (c) calculating a carrier frequency deviation and a carrier phase deviation feedback-free according to the principle of the maximum likelihood theory using a procedure selected from the group consisting of Fourier transformation and by convolution in the time domain and, thereby compensating the data sequence.
Dependencies are inferred from the claim text.