Patent ID: 7738578

Claim:
A method of selecting frequency (S F ) or time (S T ) spreading parameters or both for a communication system including a transmitter and a receiver and using a quadrature amplitude modulation and implementing a code division multiple access (CDMA) technique and orthogonal frequency division multiplexing (OFDM), in which the frequency domain is divided into F=N/S F sub-bands of S F subcarriers, N being the size of the fast Fourier transform used by the receiver and S F being the frequency spreading parameter, and the time domain is divided into T=N S /S T blocks of S T OFDM symbols, where N S is the number of OFDM symbols used to code a data frame and S T is the time spreading parameter, the method comprising: estimating attenuation coefficients of the propagation channel; determining at least one asymptotic signal-to-interference+noise ratio (SINR) for all the F sub-bands of S F subcarriers and the T blocks of S T OFDM symbols, based on the attenuation coefficients of the propagation channel and the type of equalizer used by the receiver; deducing a compressed asymptotic SINR for each coded information block obtained from the modulation expressed by an analytical formula dependent on the frequency S F and time S T spreading parameters; and selecting the frequency S F and time S T spreading parameters which maximize the value of the compressed asymptotic SINR.