The disclosure relates to an encoder for encoding a vector comprising channel state information and/or a pilot sequence. The encoder includes at least one processor; and a non-transitory computer-readable storage medium coupled to the at least one processor and storing programming instructions for execution by the at least one processor, wherein the programming instructions instruct the at least one processor to: determine a cell of a sphere mesh, wherein the cell includes the vector; determine a refined sphere mesh based on an initial sphere mesh; and determine a binary representation of a first identifier of an initial cell of the initial sphere mesh that includes the vector and a second identifier of a refined cell of the refined sphere mesh that includes the vector.