High Resolution Timing Advance Estimation Based on PRACH

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.