Data recovery using gradients

1. A method using inverse transformation of subranges of subcarriers gradients (ITSSG) for transmitted data recovery from an orthogonal frequency division multiplexing (OFDM) signal, applied to subcarriers produced by a transmission channel including a data coding circuit, encoding said transmitted data into OFDM frames defining the subcarriers, a transmission link supplying the OFDM frames and a preprocessor of received OFDM frames transforming received OFDM frames into recovered the subcarriers characterized with the subcarriers gradients; wherein the ITSSSG method comprises the steps of:

deriving the inverse transformation reversing a transfer function of the transmission channel, by processing parts of such received OFDM frame corresponding to known parts of a transmitted OFDM frame;

wherein the inverse transformation is defining recovery of the transmitted data from the subranges of the subcarriers gradients identifying subcarriers subspaces comprising the recovered subcarriers;

recovering the subcarriers maintaining a known phase relation to such received OFDM frame by applying frequency domain and time domain signal processing to such received OFDM frame;

deriving the gradients of the recovered subcarriers by calculating 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;

comparing the subcarriers gradients with references defining plurality of the subranges of the subcarriers gradients;

using results of such comparisons for identifying the subranges of the subcarriers gradients identifying the subcarriers subspaces comprising the recovered subcarriers;

applying, by using an adaptive data decoder, the inverse transformation to the identified subranges of the subcarriers gradients in order to recover the transmitted data corresponding to the received subcariers.

2. An ITSSG method as claimed in claim 1 , wherein the deriving the gradients includes detection and utilization of amplitudes and phases of maximums of the integrals of the samples.

3. An ITSSG method as claimed in claim 1 , wherein the recovering the subcarriers is implemented by utilizing a synchronous circular processor (SCP); wherein the SCP comprises:

processing stages which are sequentially connected and fed with consecutive samples derived from the received OFDM signal;

wherein the processing stages comprise consecutive circular segments designated for storing or processing of the consecutive samples derived from the received OFDM signal;

wherein the storing or processing of the consecutive samples within the processing stages is driven by circular clocks applied periodically to the consecutive circular segments contained in the processing stages;

wherein outputs of some of the consecutive circular segments contained in a respective one of said processing stages are loaded into the consecutive circular segments contained in a next one of said processing stages,

while other of the consecutive circular segments contained in the respective processing stage are loaded with next said consecutive samples.

4. An ITSSG method as claimed in claim 1 ; wherein:

a programmable control unit (PCU) is used for the processing the parts of the received OFDM frame corresponding to the known parts of the transmitted OFDM frame including utilization of theoretical models of the transmission channel;

PCU is used for controlling operations of a synchronous circular processor (SCP), wherein the SCP comprises sequentially connected processing stages driven with the clocks synchronous to the frames of the received OFDM signal and fed with samples derived from the received OFDM signal.

5. A method using inverse transformation of subcarriers subspaces using subcarriers gradients (ITSSSG) for transmitted data recovery from an orthogonal frequency division multiplexing (OFDM) signal, applied to subcarriers produced by a transmission channel including a data coding circuit, encoding said transmitted data into OFDM frames defining the subcarriers, a transmission link supplying the OFDM frames and a preprocessor of received OFDM frames transforming received OFDM frames into recovered the subcarriers characterized with the subcarriers gradients; wherein the ITSSSG method comprises the steps of:

deriving the inverse transformation reversing a transfer function of the transmission channel, by processing parts of such received OFDM frame corresponding to known parts of a transmitted OFDM frame;

wherein the inverse transformation is defining recovery of the transmitted data from the subcarriers subspaces identified with reference frames as comprising the recovered subcarriers;

recovering the subcarriers maintaining a known phase relation to such received OFDM frame by applying frequency domain and time domain signal processing to such received OFDM frame;

deriving the gradients of the recovered subcarriers, needed for selecting reference frames expected to be close to the subcarriers, by calculating 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 derived gradients for the selection of the reference frames expected to be close to the subcarriers;

comparing sets of samples of the recovered subcarriers with corresponding sets of elements of the selected reference frames;

using results of such comparisons for identifying the subcarriers subspaces which the received subcarriers belong to;

applying, by using a content addressed memory, the inverse transformation to the identified subcarriers subspaces in order to recover the transmitted data from the received subcarriers.

6. An ITSSSG method as claimed in claim 5 , wherein the deriving the gradients includes detection and utilization of amplitudes and phases of maximums of the integrals of the samples.

7. An ITSSSG method as claimed in claim 5 , wherein the recovering the subcarriers is implemented by utilizing a synchronous circular processor (SCP); wherein the SCP comprises:

processing stages which are sequentially connected and fed with consecutive samples derived from the received OFDM signal;

wherein the processing stages comprise consecutive circular segments designated for storing or processing of the consecutive samples derived from the received OFDM signal;

wherein the storing or processing of the consecutive samples within the processing stages is driven by circular clocks applied periodically to the consecutive circular segments contained in the processing stages;

wherein outputs of some of the consecutive circular segments contained in a respective one of said processing stages are loaded into the consecutive circular segments contained in a next one of said processing stages,

while other of the consecutive circular segments contained in the respective processing stage are loaded with next said consecutive samples.

8. An ITSSSG method as claimed in claim 5 ; wherein:

a programmable control unit (PCU) is used for the processing the parts of the received OFDM frame corresponding to the known parts of the transmitted OFDM frame including utilization of theoretical models of the transmission channel;

PCU is used for controlling operations of a synchronous circular processor (SCP), wherein the SCP comprises sequentially connected processing stages driven with the clocks synchronous to the frames of the received OFDM signal and fed with samples derived from the received OFDM signal.