Method, apparatus and receiver for demapping dual carrier modulated COFDM signals

An apparatus for demapping dual carrier modulated COFDM signals comprising:

• an equalization stage for performing equalization on a received dual carrier modulated COFDM signal to obtain an equalized data signal;
• a first stage arranged to normalize an estimated frequency domain channel state information signal to obtain a normalized channel state information signal;
• a second stage arranged to determine a Y-domain weighting factor from the normalized channel state information signal;
• a third stage arranged to determine an X-domain weighting factor from the normalized channel state information signal on the dual carriers;
• and
• a demapper stage arranged to weight the equalized data signal using the Y-domain weighting factor and the X-domain weighting factor to generate a weighted input signal of a DCM demapper;
• wherein the DCM demapper is arranged to perform linear demapping of the weighted input signal of the DCM demapper in the frequency domain;
• wherein the third stage is arranged to determine the X-domain weighting factor according to the equation:
• λ(i)=λ(i +N/2)=min(|Ĥ(i)|,|Ĥ(i+N/2)|), for i=0 to N/2-1, where λ(i) is the X-domain weighting factor, |Ĥ(i)| is the normalized magnitude of channel state information signal on the ith subcarrier, |Ĥ(i+N/2) is the normalized magnitude of channel state information signal on the (i+N/2)th subcarrier, and N is the number of frequency domain complex values in the received dual carrier modulated COFDM signal.

A method for demapping dual carrier modulated (DCM) coded orthogonal frequency-division multiplexing (COFDM) signals comprising:

• performing equalization on a received dual carrier modulated COFDM signal to obtain an equalized data signal;
• normalizing an estimated frequency domain channel state information signal to obtain a normalized channel state information signal;
• determining a Y-domain weighting factor from the normalized channel state information signal;
• determining an X-domain weighting factor from the normalized channel state information signal on the dual carriers;
• weighting the equalized data signal using the Y-domain weighting factor and the X-domain weighting factor to generate a weighted input signal of a DCM demapper;
• and
• performing linear demapping of the weighted input signal in the frequency domain in the DCM demapper;
• wherein the step of determining the Y-domain weighting factor comprises determining the Y-domain weighting factor according to the equation:
• ρ(k)=min(|Ĥ(k)|,σ), for k=0 to N−1, where ρ(k) is the Y-domain weighting factor, |Ĥ(k)| is the normalized magnitude of channel state information signal on the kth subcarrier, σ is an empirical constant and N is the number of frequency domain complex values in the received dual carrier modulated COFDM signal.

An apparatus for demapping dual carrier modulated COFDM signals comprising:

• an equalization stage for performing equalization on a received dual carrier modulated COFDM signal to obtain an equalized data signal;
• a first stage arranged to normalize an estimated frequency domain channel state information signal to obtain a normalized channel state information signal;
• a second stage arranged to determine a Y-domain weighting factor from the normalized channel state information signal;
• a third stage arranged to determine an X-domain weighting factor from the normalized channel state information signal on the dual carriers;
• and
• a demapper stage arranged to weight the equalized data signal using the Y-domain weighting factor and the X-domain weighting factor to generate a weighted input signal of a DCM demapper;
• wherein the DCM demapper is arranged to perform linear demapping of the weighted input signal of the DCM demapper in the frequency domain;
• and
• wherein the second stage is arranged to determine the Y-domain weighting factor according to the equation:
• ρ(k)=min(|Ĥ(k)|,σ), for k=0 to N−1, where ρ(k) is the Y-domain weighting factor, |Ĥ(k)| is the normalized magnitude of channel state information signal on the kth subcarrier, σ is an empirical constant and N is the number of frequency domain complex values in the received dual carrier modulated COFDM signal.