Mapping indication in mixed OFDM numerology

An integrated circuit for a transmission device, the integrated circuit comprising:

• mapping circuitry which, in operation, maps one or both of data and a reference signal onto a resource unit of a communication system,
• the resource unit including subcarriers of a first numerology and subcarriers of a second numerology,
• the subcarriers of the first numerology being orthogonal to each other, and
• the subcarriers of the second numerology being orthogonal to each other,
• the first numerology having a larger subcarrier spacing than the second numerology,
• subcarriers of the first and the second numerologies are frequency-multiplexed on a subcarrier basis,
• the subcarriers of the second numerology including inter-numerology-orthogonal subcarriers and non-inter-numerology-orthogonal subcarriers,
• each of the inter-numerology-orthogonal subcarriers being aligned with a respective subcarrier of the subcarriers of the first numerology, and each of the non-inter-numerology-orthogonal subcarriers being unaligned with the subcarriers of the first numerology and between two adjacent subcarriers of the first numerology,
• the mapped one or both of the data and the reference signal being mapped to a subcarrier that is among the subcarriers of the first numerology and among the inter-numerology-orthogonal subcarriers;
• and
• transmitting circuitry which, in operation, transmits the mapped one or both of the data and the reference signal on the resource unit, and transmits an indication of a mapping of the mapped one or both of the data and the reference signal on the resource unit, wherein
• the indication is configured to reference subcarriers among a group of subcarriers that includes the subcarriers of the first numerology and the inter-numerology-orthogonal subcarriers, and excludes the non-inter-numerology-orthogonal subcarriers.