Achieving synchronization in an orthogonal time frequency space signal receiver
Methods, systems and device for achieving synchronization in an orthogonal time frequency space (OTFS) signal receiver are described. An exemplary signal reception technique includes receiving an OTFS modulated wireless signal comprising pilot signal transmissions interspersed with data transmissions, calculating autocorrelation of the wireless signal using the wireless signal and a delayed version of the wireless signal that is delayed by a pre-determined delay, thereby generating an autocorrelation output, processing the autocorrelation filter through a moving average filter to produce a fine timing signal. Another exemplary signal reception technique includes receiving an OTFS modulated wireless signal comprising pilot signal transmissions interspersed with data transmissions, performing an initial automatic gain correction of the received OTFS wireless signal by peak detection and using clipping information, performing coarse automatic gain correction on results of a received and initial automatic gain control (AGC)-corrected signal.
1. A signal reception method, comprising:
receiving an orthogonal time frequency space (OTFS) modulated wireless signal comprising pilot signal transmissions interspersed with data transmissions;
calculating an autocorrelation of the wireless signal using the wireless signal and a delayed version of the wireless signal that is delayed by a pre-determined delay, thereby generating an autocorrelation output, wherein the pre-determined delay is equal to a time spacing between successive pilot signal transmissions;
processing the autocorrelation output through a moving average filter to produce a fine timing signal; and
performing synchronization with the wireless signal using the fine timing signal.
2. The method of claim 1 , further including:
identifying frame boundaries for data transmissions based on the autocorrelation output.
3. The method of claim 1 , wherein the moving average filter operates over a number of samples equal to sum of lengths of cyclic prefix and cyclic suffix field.
4. The method of claim 1 , further including:
determining magnitudes of autocorrelation peaks, and
performing gain adjustment based on the magnitudes of the autocorrelation peaks.
5. The method of claim 4 , wherein the autocorrelation peaks are determined using an exponential windowing function.
6. The method of claim 2 , wherein the identifying operation includes performing a linear fit operation on the autocorrelation output.
7. The method of claim 1 , wherein the method further includes, during the performing synchronization, determining a symbol timing offset value for symbols in the OTFS modulated wireless signal.
8. A wireless communication device comprising a processor and transceiver circuitry wherein the transceiver circuitry is configured for:
receiving an orthogonal time frequency space (OTFS) modulated wireless signal comprising pilot signal transmissions interspersed with data transmissions; and
wherein the processor is configured for:
calculating autocorrelation of the wireless signal using the wireless signal and a delayed version of the wireless signal that is delayed by a pre-determined delay, thereby generating an autocorrelation output, wherein the pre-determined delay is equal to time spacing between successive pilot signal transmissions;
processing the autocorrelation output through a moving average filter to produce a fine timing signal; and
performing synchronization with the wireless signal using the fine timing signal.
9. The wireless communication device of claim 8 , wherein the processor is further configured for:
identifying frame boundaries for data transmissions based on the autocorrelation output.
10. The wireless communication device of claim 8 , wherein the moving average filter operates over a number of samples equal to sum of lengths of cyclic prefix and cyclic suffix field.
11. The wireless communication device of claim 8 , wherein the processor is further configured for:
determining magnitudes of autocorrelation peaks, and
performing gain adjustment based on the magnitudes of the autocorrelation peaks.
12. The wireless communication device of claim 11 , wherein the autocorrelation peaks are determined using an exponential windowing function.
13. The wireless communication device of claim 9 , wherein the identifying operation includes performing a linear fit operation on the autocorrelation output.
14. The wireless communication device of claim 8 , wherein the processor is further configured to determine, during the performing synchronization, a symbol timing offset value for symbols in the OTFS modulated wireless signal.
15. The wireless communication device of claim 8 , wherein the processor is further configured for:
detecting at least one autocorrelation peak in the fine timing signal,
wherein the samples corresponding to the at least one autocorrelation peak comprise a first number consecutive samples with a positive slope followed by a second number of consecutive samples with a negative slope, and
wherein a magnitude of each of the samples is above a noise floor.