<p>A multi-pilot frame handler (36) of a radio access network node (28) is arranged to prepare a block of a frame of information to include a first pilot signal of a pilot signal first type and a first pilot signal of a pilot signal second type. The pilot signal of the pilot signal first type is expressed as a first Costas array base pattern of resource elements of the block; the pilot signal of the second type is expressed as a second Costas array base pattern of resource elements of the block. The multi-pilot frame handler (36) is arranged to prepare the block so that any pilot signal of the pilot signal first type is carried by at least some subcarriers of a first set of subcarriers of the block and any pilot signal of the pilot signal second type is carried by at least some subcarriers of a second set of subcarriers of the block.</p>
