Data recovery using subcarriers gradients

A method for data recovery using gradients of sub-carriers (DRGS) of a received orthogonal frequency division multiplexing (OFDM) signal, for selecting reference frames defining subspaces of sub-carriers corresponding to transmitted data symbols, wherein the DRGS method comprises the steps of:

• oversampling of the received OFDM signal;
• recovering the sub-carriers from the oversampled OFDM signal by using a frequency sampling filter;
• deriving the reference frames defining the subspaces of the sub-carriers corresponding to the transmitted data symbols and deriving an assignment of the transmitted data symbols to the reference frames;
• estimating the gradients by using integrals of samples of the recovered sub-carriers surrounding a middle one of the samples;
• wherein amplitudes of previous the samples are subtracted from amplitudes of following the samples shifted forward by the same number of sampling periods as the previous samples are trailing such middle sample;
• wherein any one of the integrals of the samples is derived by adding all results of such subtractions made over a proper part of a sub-carrier cycle surrounding the middle sample;
• using the estimates of the gradients for selecting reference frames which are expected to be closer to the recovered sub-carriers;
• calculating integrals of deviations between the selected reference frames and the recovered sub-carriers;
• using the integrals of the deviations to identify the selected reference frames which are closest to the recovered sub-carriers;
• recovering the transmitted data symbols corresponding to the received OFDM signal by applying the derived assignment of the transmitted data symbols to the identified selected reference frames.

A method for data recovery using subranges of gradients of sub-carriers (DRGS) of a received orthogonal frequency division multiplexing (OFDM) signal, for selecting reference frames defining subspaces of sub-carriers corresponding to transmitted data symbols;

• wherein the DRGS method comprises the steps of:
• oversampling of the received OFDM signal;
• recovering the sub-carriers from the oversampled OFDM signal by using a frequency sampling filter;
• deriving the reference frames defining the subspaces of the sub-carriers corresponding to the transmitted data symbols and deriving an assignment of the transmitted data symbols to the reference frames;
• defining subranges of the gradients corresponding to the reference frames and defining an assignment of the reference frames to the defined subranges;
• estimating the gradients by using integrals of samples of the recovered sub-carriers surrounding a middle one of the samples;
• wherein amplitudes of previous the samples are subtracted from amplitudes of following the samples shifted forward by the same number of sampling periods as the previous samples are trailing such middle sample;
• wherein any one of the integrals of the samples is derived by adding all results of such subtractions made over a proper part of a sub-carrier cycle surrounding the middle sample;
• identifying the defined subranges which the estimates of the gradients belong to;
• using the identified defined subranges for selecting those of the reference frames which are expected to be closer to the recovered sub-carriers, by applying the defined assignment of the reference frames to the identified defined subranges;
• calculating integrals of deviations between the selected reference frames and the recovered OFDM sub-carriers;
• using the integrals of the deviations to identify the selected reference frames which are closest to the recovered subcarriers;
• recovering the transmitted data symbols corresponding to the received OFDM signal by applying the derived assignment of the transmitted data symbols to the identified selected reference frames.