Data recovery from sub-carriers
The data recovery from sub-carriers (DRSC) of a received OFDM signal, contributes a method and a circuit for utilizing parameters of OFDM sub-carriers comprised in the received OFDM signal or subspaces comprising the OFDM sub-carriers for recovering transmitted data symbols from the received OFDM signal affected by deterministic and random distortions introduced by a transmission link.
1. A method for data recovery from sub-carriers (DRSC) of a received orthogonal frequency division multiplexing (OFDM) signal, by utilizing parameters of the OFDM sub-carriers comprised in the received OFDM signal; wherein the DRSC method comprises the steps of:
oversampling of the received OFDM signal;
sampling of frequencies occurring in the oversampled OFDM signal in order to recover the OFDM sub-carriers from the oversampled OFDM signal,
wherein the sampling of frequencies and the recovery of the OFDM sub-carriers are implemented with a real time processor driven by clocks synchronous to frames of the received OFDM signal;
processing the oversampled OFDM signal in order to define an inverse transfer function designed to reverse distortions introduced by a transmission link to the received OFDM signal;
estimating amplitudes and phases of the recovered OFDM sub-carriers by processing the recovered OFDM sub-carriers;
reversing the distortions introduced by the transmission link by utilizing the defined inverse transfer function for transforming the estimated amplitudes and phases;
using the transformed amplitudes and phases for recovering data symbols encoded originally in a transmitted OFDM signal.
2. A DRSC method as claimed in claim 1 , wherein the real time processor 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.
3. A DRSC method as claimed in claim 1 , wherein:
the estimating the amplitudes and phases of the recovered OFDM sub-carriers, is implemented by utilizing estimates of amplitudes and phases of singular half-cycles or cycles of the recovered OFDM sub-carriers.
4. A DRSC method as claimed in claim 3 , wherein the DRSC method further comprises the step of:
selecting data symbols corresponding to every one of the recovered OFDM sub-carriers by using statistical methods for processing a plurality of data symbols recovered using the estimates of the amplitudes and phases of half-cycles or cycles of the every one of the recovered OFDM sub-carriers;
wherein an amplitude and phase of the everyone of the recovered OFDM sub-carriers is assumed as corresponding to a respective one of the selected data symbols.
5. A DRSC method as claimed in claim 3 , wherein the real time processor 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.
6. A method for data recovery from sub-carriers (DRSC) of a received orthogonal frequency division multiplexing (OFDM) signal produced by a transmission system transforming transmitted data symbols into the received OFDM signal, by utilizing parameters of the OFDM sub-carriers comprised in the received OFDM signal; wherein the DRSC method comprises the steps of:
oversampling of the received OFDM signal;
sampling of frequencies occurring in the oversampled OFDM signal in order to recover the OFDM subcarriers from the oversampled OFDM signal,
wherein the sampling of the frequencies and the recovery of the OFDM sub-carriers are implemented with a real time processor driven by clocks synchronous to frames of the received OFDM signal;
processing theoretical models of the transmission system or the oversampled OFDM signal captured during a training session or a data transmission operation,
in order to define a relation between the transmitted data symbols and sub-ranges of the parameters of the OFDM sub-carriers wherein the sub-ranges of the parameters are corresponding to the transmitted data symbols;
deriving the parameters of the recovered OFDM sub-carriers by utilizing amplitudes and phases of the recovered OFDM sub-carriers;
recovering the transmitted data symbols corresponding to the received OFDM signal by utilizing the defined relation between the transmitted data symbols and the sub-ranges of the parameters which the derived parameters belong to.
7. A DRSC method as claimed in claim 6 , wherein the real time processor 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. A DRSC method as claimed in claim 6 , wherein the real time processor is implemented by utilizing a synchronous circular processor (SCP) and an on-line processor is implemented by utilizing a programmable control unit (PCU); wherein:
the PCU is used for the processing the theoretical models of the transmission system or the oversampled OFDM signal captured during the training session or the data transmission operation;
the PCU is used for controlling operations of the 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.
9. A DRSC method as claimed in claim 6 , wherein:
the deriving the parameters of the recovered OFDM sub-carriers, is implemented by utilizing amplitudes and phases of half-cycles or cycles of the recovered OFDM sub-carriers.
10. A DRSC method as claimed in claim 9 , wherein the DRSC method further comprises the step of:
selecting data symbols corresponding to every one of the recovered OFDM sub-carriers by using statistical methods for processing a plurality of data symbols recovered using the estimates of the amplitudes and phases of half-cycles or cycles of the every one of the recovered OFDM sub-carriers;
wherein an amplitude and phase of the every one of the recovered OFDM sub-carriers is assumed as corresponding to a respective one of the selected data symbols.
11. A DRSC method as claimed in claim 9 , wherein the real time processor 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.
12. A DRSC method as claimed in claim 9 , wherein the real time processor is implemented by utilizing a synchronous circular processor (SCP) and an on-line processor is implemented by utilizing a programmable control unit (PCU); wherein:
the PCU is used for the processing the theoretical models of the transmission system or the oversampled OFDM signal captured during the training session or the data transmission operation;
the PCU is used for controlling operations of the 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.
13. A method for data recovery from sub-carriers (DRSC) of a received orthogonal frequency division multiplexing (OFDM) signal produced by a transmission system transforming transmitted data symbols into the received OFDM signal, by utilizing subspaces of sub-carriers of the received OFDM signal wherein every one of the subspaces comprises a set of the OFDM sub-carriers corresponding to a particular one of the transmitted data symbols; wherein the DRSC method comprises the steps of:
oversampling of the received OFDM signal;
sampling of frequencies occurring in the oversampled OFDM signal in order to recover the OFDM sub-carriers from the oversampled OFDM signal,
wherein the sampling of the frequencies and the recovery of the OFDM sub-carriers are implemented with a real time processor driven by clocks synchronous to frames of the received OFDM signal;
processing theoretical models of the transmission system or the oversampled OFDM signal captured during a training session or a data transmission operation,
in order to define a relation between the transmitted data symbols and the subspaces;
deriving proximity estimates between the recovered OFDM sub-carriers and reference frames outlining the subspaces, in order to identify the subspaces comprising the recovered OFDM sub-carriers;
recovering the transmitted data symbols corresponding to the received OFDM signal by utilizing the defined relation applied to the identified subspaces comprising the recovered OFDM subcarriers.
14. A DRSC method as claimed in claim 13 , wherein the real time processor 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.
15. A DRSC method as claimed in claim 13 , wherein the real time processor is implemented by utilizing a synchronous circular processor (SCP) and an on-line processor is implemented by utilizing a programmable control unit (PCU); wherein:
the PCU is used for the processing the theoretical models of the transmission system or the oversampled OFDM signal captured during the training session or the data transmission operation;
the PCU is used for controlling operations of the 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.