High Resolution Timing Advance Estimation Based on PRACH

A non-transitory computer-readable medium containing instructions for providing high resolution timing advance estimation based on Physical Random Access Channel (PRACH), which, when executed, cause a processing device to perform steps comprising:

• receiving a preamble signal r(n) having a predetermined sampling frequency and a predetermined length;
• correlating a down sampled version of the received preamble with a reference preamble sequence c(n) using an FFT method to provide correlation output Ryc;
• using a peak value P of the correlation output Ryc to detect a preamble ID and a timing advance at a resolution of 24Ts;
• zero padding sequences Y(k) and C(k) so that they have a predetermined length resulting in sequences Y_hat(k) and C_hat(k), wherein Y(k) and C(k) are 1024-point FFT of y(n) and c(n);
• performing a maximum likelihood estimation (MLE) to estimate a timing offset;
• and
• detecting a peak value out of the R_hat(m) and using a corresponding index Q to provide a timing advance with an accuracy of 2Ts.

A system for providing for providing high resolution timing advance estimation based on Physical Random Access Channel (PRACH), the system including a processing device which performs steps comprising:

• receiving a preamble signal r(n) having a predetermined sampling frequency and a predetermined length;
• correlating a down sampled version of the received preamble with a reference preamble sequence c(n) using an FFT method to provide correlation output Ryc;
• using a peak value P of the correlation output Ryc to detect a preamble ID and a timing advance at a resolution of 24Ts;
• zero padding sequences Y(k) and C(k) so that they have a predetermined length resulting in sequences Y_hat(k) and C_hat(k), wherein Y(k) and C(k) are 1024-point FFT of y(n) and c(n);
• performing a maximum likelihood estimation (MLE) to estimate a timing offset;
• and
• detecting a peak value out of the R_hat(m) and using a corresponding index Q to provide a timing advance with an accuracy of 2Ts.

A method, comprising:

• receiving a preamble y(n) from a user equipment in a frequency domain;
• performing a Fourier transform on the received preamble y(n) to generate a received time-domain preamble y(k);
• performing a Fourier transform on a reference preamble c(n) to generate a time-domain reference preamble c(k);
• performing an inverse Fourier transform on a dot product of the received time-domain preamble y(k) and the reference time-domain preamble c(k) to generate a correlation function R;
• padding the received time-domain preamble y(k) and the reference time-domain preamble c(k) to a certain length with zeroes;
• using a peak value P of the correlation function R to detect a preamble identifier;
• performing an inverse discrete Fourier transform on the dot product of the received time-domain preamble y(k) and the reference time-domain preamble c(k) at a plurality of positions within a sparse timing hypothesis window L, the sparse timing hypothesis window L based on the preamble identifier, to generate a second correlation function R_hat;
• and
• using a peak value Q of the second correlation function R_hat to determine a timing advance value.