Systems and methods for fast acquisition of a primary synchronization signal for 5G new radio network

1 . A method for acquiring a primary synchronization signal, the method comprising:

receiving a radio frequency (RF) broadcast signal at user equipment;

performing, with the user equipment, a time direction differential correlation between a first section of the RF broadcast signal and a second section of the RF broadcast signal;

summing together, with the user equipment, sections of an output of the time direction differential correlation that are separated by a preconfigured distance;

identifying, with the user equipment, a preconfigured number of peak values in results of the summing;

converting, with the user equipment, the first section and the second section of the RF broadcast signal into frequency domain versions of the first section and the second section that are localized to locations of the preconfigured number of peak values;

performing, with the user equipment, frequency direction differential correlations between the frequency domain versions of the first section and the second section;

identifying, with the user equipment, maximum values of a ratio between outputs of the frequency direction differential correlations;

identifying, with the user equipment, ones of the maximum values of the ratio that are greater than or equal to a preconfigured threshold value;

searching, with the user equipment, for a primary synchronization signal (PSS) in localized regions of the RF broadcast signal, wherein the localized regions are defined in the time domain by the preconfigured number of peak values in the results of the summing and in the frequency domain by the ones of the maximum values of the ratio that are greater than or equal to a preconfigured threshold value.

2 . The method of claim 1 wherein the preconfigured number of peak values is eight.

3 . The method of claim 1 wherein the preconfigured distance is equal to a length of two orthogonal frequency-division multiplexing symbols.

4 . The method of claim 1 further comprising:

receiving the RF broadcast signal by sampling the RF broadcast signal at a length equivalent to at least two synchronization signal block (SSB) periods; and

separating the RF broadcast signal into the first section and the second section such that the first section and the second section have respective lengths equivalent to at least one SSB period.

5 . The method of claim 1 wherein time domain boundaries of the localized regions defined by the preconfigured number of peak values in the results of the summing are plus and minus a cyclic prefix (CP) length of time around a respective sample time value of each of the preconfigured number of peak values, and wherein frequency domain boundaries of the localized regions defined by the ones of the maximum values of the ratio that are greater than or equal to the preconfigured threshold value are plus and minus five frequency bins around a respective frequency offset value of each of the maximum values of the ratio greater than or equal to the preconfigured threshold value.

6 . The method of claim 1 wherein the frequency direction differential correlations include a PSS correlation and a zero energy block correlation, and wherein the ratio is calculated by dividing the PSS block correlation by the zero energy block correlation for each frequency bin in the outputs of the frequency direction differential correlations.

7 . The method of claim 1 further comprising performing the time direction differential correlation using a sliding widow method by:

filling a circular buffer of the user equipment is up to a correlation length with conjugate complex multiplications;

outputting a summation of the conjugate complex multiplications as an initial correlation value;

for each new time value sample offset of the first section and the second section,

fetching an oldest entry of the circular buffer;

subtracting the oldest entry from the previously output correlation value;

after the oldest entry is subtracted, calculating a new conjugate complex multiplication and saving to the circular as the newest entry; and

adding the new conjugate complex multiplication to the previously output correlation value.

8 . The method of claim 1 further comprising performing the frequency direction differential correlations using a sliding widow method by:

filling a circular buffer of the user equipment is up to a correlation length with conjugate complex multiplications;

outputting a summation of the conjugate complex multiplications as an initial correlation value;

for each new frequency value sample offset of the first section and the second section, fetching an oldest entry of the circular buffer;

subtracting the oldest entry from the previously output correlation value;

after the oldest entry is subtracted, calculating a new conjugate complex multiplication and saving to the circular buffer as the newest entry; and

adding the new conjugate complex multiplication to the previously output correlation value.

9 . The method of claim 1 further comprising:

verifying and decoding a secondary synchronization signal, data modulation reference signal (PECH DM-RS) and Master Information Block (MIB) of the RF broadcast signal with a PSS identified from searching the localized regions.

10 . The method of claim 1 wherein the RF broadcast signal is a 5G new radio broadcast signal.

11 . A system for acquiring a primary synchronization signal with user equipment, the system comprising:

a radio frequency (RF) transceiver of the user equipment configured to receive an RF broadcast signal; and

a programmable processor of the user equipment configured to receive the RF broadcast signal from the RF transceiver, and wherein the programmable processor is configured to:

execute a time direction differential correlation between a first section of the RF broadcast signal and a second section of the RF broadcast signal;

sum together sections of an output of the time direction differential correlation that are separated by a preconfigured distance; identify a preconfigured number of peak values in results of the summation;

convert the first section and the second section of the RF broadcast signal into frequency domain versions of the first section and the second section that are localized to locations of the preconfigured number of peak values;

execute frequency direction differential correlations between the frequency domain versions of the first section and the second section;

identify maximum values of a ratio between outputs of the frequency direction differential correlations;

identify ones of the maximum values of the ratio that are greater than or equal to a preconfigured threshold value; and

search for a primary synchronization signal (PSS) in localized regions of the RF broadcast signal, wherein the localized regions are defined in the time domain by the preconfigured number of peak values in the results of the summing and in the frequency domain by the ones of the maximum values of the ratio that are greater than or equal to a preconfigured threshold value.

12 . The system of claim 11 wherein the preconfigured number of peak values is eight.

13 . The system of claim 11 wherein the preconfigured distance is equal to a length of two orthogonal frequency-division multiplexing symbols.

14 . The system of claim 11 wherein the RF transceiver is further configured to receive the RF broadcast signal by sampling the RF broadcast signal at a length equivalent to at least two synchronization signal block (SSB) periods; and

wherein the programmable processor is further configured to separate the RF broadcast signal into the first section and the second section such that the first section and the second section have respective lengths equivalent to at least one SSB period.

15 . The system of claim 11 wherein time domain boundaries of the localized regions defined by the preconfigured number of peak values in the results of the summation are plus and minus a cyclic prefix (CP) length of time around a respective sample time value of each of the preconfigured number of peak values, and wherein frequency domain boundaries of the localized regions defined by the ones of the maximum values of the ratio that are greater than or equal to the preconfigured threshold value are plus and minus five frequency bins around a respective frequency offset value of each of the maximum values of the ratio greater than or equal to the preconfigured threshold value.

16 . The system of claim 11 wherein the frequency direction differential correlations include a PSS correlation and a zero energy block correlation, and wherein the programmable processor is further configured to calculate the ratio by dividing the PSS block correlation by the zero energy block correlation for each frequency bin in the outputs of the frequency direction differential correlations.

17 . The system of claim 11 wherein the programmable processor executing the time direction differential correlation includes using a sliding widow method wherein the programmable processor is configured to:

fill a circular buffer of the user equipment is up to a correlation length with conjugate complex multiplications;

output a summation of the conjugate complex multiplications as an initial correlation value;

sample off set of the first section and the second section, fetch an oldest entry of the circular buffer;

subtract the oldest entry from the previously output correlation value;

after the oldest entry is subtracted, calculate a new conjugate complex multiplication and save to the circular buffer as the newest entry; and

add the new conjugate complex multiplication to the previously output correlation value.

18 . The system of claim 11 wherein the programmable processor executing the frequency direction differential correlations includes using a sliding widow method wherein the programmable processor is configured to:

fill a circular buffer of the user equipment is up to a correlation length with conjugate complex multiplications;

output a summation of the conjugate complex multiplications as an initial correlation value;

for each new frequency value sample offset of the first section and the second section, fetch an oldest entry of the circular buffer;

subtract the oldest entry from the previously output correlation value;

after the oldest entry is subtracted, calculate a new conjugate complex multiplication and save to the circular buffer as the newest entry; and

add the new conjugate complex multiplication to the previously output correlation value.

19 . The system of claim 11 wherein the programmable processor is further configured to verify and decode a secondary synchronization signal, data modulation reference signal (PECH DM-RS) and Master Information Block (MIB) of the RF broadcast signal with a PSS identified from searching the localized regions.

20 . The system of claim 11 wherein the RF broadcast signal is a 5G new radio broadcast signal.