A device (10, 20, 30) comprising: a searching unit (12, 22, 32) configured to search a set of specific sequences, comprising a set of root sequences and cyclic shifts thereof, wherein the searching unit (12, 22, 32) is configured to start from a root sequence index indicating a root sequence of ordered root sequences, include available cyclic shifts of the root sequence, and continue with a next root sequence if necessary for filling the set, wherein the ordered root sequences are obtained by ordering sequences of a predetermined length and number in accordance with cubic metric of each of the sequences and a size of a high mobility cell each of the sequences supports, wherein the ordering comprises: - dividing the sequences into a first set with cubic metric values below a predetermined threshold and a second set with cubic metric values above the threshold, - forming two or more subsets of the sequences in the first set and two or more subsets of the sequences in the second set according to the supported cell sizes, wherein the subsets are arranged such that supported cell sizes of the sequences increase between subsets of the first set and decrease between subsets of the second set or vice versa, and - ordering the sequences in each subset according to their cubic metric values, wherein the sequences of every second subset are ordered with decreasing cubic metric values and of every other subset with increasing cubic metric values. a searching unit (12, 22, 32) configured to search a set of specific sequences, comprising a set of root sequences and cyclic shifts thereof, wherein the searching unit (12, 22, 32) is configured to start from a root sequence index indicating a root sequence of ordered root sequences, include available cyclic shifts of the root sequence, and continue with a next root sequence if necessary for filling the set, wherein the ordered root sequences are obtained by ordering sequences of a predetermined length and number in accordance with cubic metric of each of the sequences and a size of a high mobility cell each of the sequences supports, wherein the ordering comprises: - dividing the sequences into a first set with cubic metric values below a predetermined threshold and a second set with cubic metric values above the threshold, - forming two or more subsets of the sequences in the first set and two or more subsets of the sequences in the second set according to the supported cell sizes, wherein the subsets are arranged such that supported cell sizes of the sequences increase between subsets of the first set and decrease between subsets of the second set or vice versa, and - ordering the sequences in each subset according to their cubic metric values, wherein the sequences of every second subset are ordered with decreasing cubic metric values and of every other subset with increasing cubic metric values. - dividing the sequences into a first set with cubic metric values below a predetermined threshold and a second set with cubic metric values above the threshold, - forming two or more subsets of the sequences in the first set and two or more subsets of the sequences in the second set according to the supported cell sizes, wherein the subsets are arranged such that supported cell sizes of the sequences increase between subsets of the first set and decrease between subsets of the second set or vice versa, and - ordering the sequences in each subset according to their cubic metric values, wherein the sequences of every second subset are ordered with decreasing cubic metric values and of every other subset with increasing cubic metric values.