DCM OFDM Signal Decoding Systems

摘要

We describe a method of decoding a DCM (dual carrier modulation) modulated OFDM signal, the method comprising: inputting first and second received signals representing modulation of a multibit data symbol onto respective first and second carriers of said OFDM signal using respective different first and second constellations; determining a combined representation of said first and second received signal data, representing a combination of a distance of a point representing a bit value of said multibit data from a constellation point in each of said different constellations; and determining a decoded value of a data bit of said multibit data using said combined representation. The combined representation may be the sum of the distances from the points in each constellation. The combined value is used to perform a log-likelihood ratio (LLR) calculation in the decoder. Signal-to-noise and ADC quantisation noise data for each carrier or pair of carriers may be taken into account in the LLR calculation. Also disclosed is a method whereby decoding is performed using an intermediate signal comprising a product of of the received signal and a complex conjugate of the channel estimate. Applications include Ultrawide Band (UWB) systems.