Patent ID: 7929630

Claim:
In a base-band receiver, a method for coherently tracking and decoding a received 16-QAM encoded data signal comprising a plurality of data symbols, the method comprising: (a) demodulating the received 16-QAM encoded data signal to generate an in-phase component and a quadrature-phase component of the encoded data signal; (b) integrating the in-phase component during each data symbol interval; (c) integrating the quadrature-phase component during each data symbol interval; (d) combining results of the integrations in (b) and (c) to generate a received signal vector, wherein coordinates of the received signal vector represent the in-phase and quadrature-phase component, respectively, of the received encoded 16-QAM data signal; (e) correcting the received signal vector according to a correction algorithm by modifying the coordinates of the received signal vector with coordinates of a current reference signal vector to generate a corrected received signal vector; (f) determining a decision index and a decoded binary value for each of the plurality of data symbols corresponding to one of 16 constellation points arranged in a 4×4 square array in a constellation diagram with 16 predetermined states, according to a decision-making algorithm using the corrected received signal vector; (g) transforming the received signal vector according to a tracking algorithm using the decision index to generate a transformed received signal vector; and (h) updating the coordinates of the current reference signal vector using computed values of the transformed received signal vector averaged over a predetermined sequence of data symbols.