Methods, systems, and devices are disclosed for digital wireless communication, and more specifically, for the use of pilot sequences that improves performance of channel estimation. In one exemplary aspect, a method of wireless communication performed by a communication node is disclosed. The method includes determining, using a first index, a mask sequence from a plurality of pre-determined mask sequences, wherein the plurality of pre-determined mask sequences is determined based on permutations of values 1, −1, i, and −i or permutations of values 1+i, or 1−i, or −1+i, or −1−i; determining a Walsh sequence using a second index, wherein the Wash sequence has a same length as the mask sequence; generating a pilot sequence by combining the mask sequence and the Walsh sequence; and performing a wireless transmission using the pilot sequence.