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 between a first root sequence of the ordered root sequences and a last root sequence of the 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 predetermined 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 the cubic metric, wherein each subset has a direction of ordering that reflects either an increasing or a decreasing cubic metric direction, wherein a subset of the two or more subsets of the first set has a direction of ordering that is opposite that of adjacent subsets of the first set, and wherein a subset of the two or more subsets of the second set has a direction of ordering that is opposite that of adjacent subsets of the second set. 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 between a first root sequence of the ordered root sequences and a last root sequence of the 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 predetermined 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 the cubic metric, wherein each subset has a direction of ordering that reflects either an increasing or a decreasing cubic metric direction, wherein a subset of the two or more subsets of the first set has a direction of ordering that is opposite that of adjacent subsets of the first set, and wherein a subset of the two or more subsets of the second set has a direction of ordering that is opposite that of adjacent subsets of the second set. - 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 predetermined 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 the cubic metric, wherein each subset has a direction of ordering that reflects either an increasing or a decreasing cubic metric direction, wherein a subset of the two or more subsets of the first set has a direction of ordering that is opposite that of adjacent subsets of the first set, and wherein a subset of the two or more subsets of the second set has a direction of ordering that is opposite that of adjacent subsets of the second set.