Patent ID: 6519296
Filing Date: 2003-02-11
Classification: H04L

Abstract:
A receiver for receiving and demodulating a received signal comprising a transmitted burst of modulated symbols, each burst of symbols being partitioned into at least two pilot inter-symbol interval segments of differing lengths, each segment comprising at least one pilot symbol, and at least one segment comprising a combination of pilot and data symbols, the receiver comprising:selection circuitry for selecting the pilot symbols in the respective segments of the transmitted burst; circuitry for calculating an estimate of the received signal's carrier from the pilot symbols in the shorter pilot inter-symbol interval segment and for providing the complex conjugate thereof; circuitry for estimating the received signal's carrier frequency based on pilot symbols received during the shorter pilot inter-symbol interval segment; circuitry for generating the complex conjugate of the estimated carrier at the pilot symbol sample times for the longer pilot inter-symbol interval segment from the estimate of the received signal's carrier frequency; a first multiplier for multiplying the pilot symbols for the longer pilot inter-symbol interval segment by the complex conjugate of the estimated carrier for the longer pilot inter-symbol interval segment; circuitry for calculating an estimate of the received signal's residual carrier based on the output of the first multiplier and for providing the complex conjugate thereof; a second multiplier for multiplying the complex conjugate of the estimated carrier for the longer pilot inter-symbol interval segment by the complex conjugate of the estimate of the received signal's residual carrier for the longer pilot inter-symbol interval segment; a switch for selecting between the complex conjugate of the estimated carrier for the shorter pilot inter-symbol interval segment and the output of the second multiplier; a third multiplier for receiving, through a delay circuit, the delayed received symbols, and for multiplying the delayed received symbols by the estimated carrier selected by the switch for demodulating the shorter and longer pilot inter-symbol interval segments, respectively, depending on the position of the switch; and a detection filter for receiving the output of the third multiplier and for providing demodulated soft output data therefrom.