Abstract: Terminal transmission method and the received signal model are used to develop two methods that estimate the starting time vicinity associated with a random access channel (RACH). First of said methods, called In*Qn RACH starting time vicinity estimation (STVE), multiplies the In and Qn branches of a sample and exacts the starting time of a preamble signal from the peak output of the phase metrics expression (for both even and odd periodicity). The second method, called (In+jQn)2 RACH STVE, performs a square operation on the received complex signal and calculates the peak output of the corresponding phase metric to extract the exact starting time of a preamble signal.