A method of facilitating a user equipment (UE) communicating with a base station (BS) via a cell of a mobile communications system is disclosed. The UE selects a random access preamble (RAP) from a set of RAPs and transmits the RAP to the BS. The BS receives the RAP and estimates a time of arrival of the RAP. A pre-defined set is used in generating the set of RAPs via at least one Zadoff-Chu sequence. The pre-defined set includes all of the following values: 0, 13, 15, 18, 22, 26, 32, 38, 46, 59, 76, 93, 119, 167, 279, 419.