This document discloses a solution for generating a reference symbol sequence for a radio transmitter. According to an aspect, a method comprises in a transmitter apparatus: generating a Zadoff-Chu sequence for a reference signal; performing a frequency-domain cyclic shift on the Zadoff-Chu sequence; extending the cyclically shifted sequence to a desired length; performing a time-domain cyclic shift on the sequence having the desired length, resulting in a reference symbol sequence; arranging the reference symbol sequence to at least some resource elements of a set of physical resource blocks, and causing transmission of the reference symbol sequence in the set of physical resource blocks.