Communication apparatus and control signal mapping method

A communication apparatus comprising:

• circuitry, which, in operation, generates a Demodulation Reference Signal (DMRS) and receives downlink control information indicating a mapping pattern of the DMRS from a plurality of mapping patterns;
• and
• a transmitter, which, in operation, transmits the DMRS and the downlink control information,
• wherein the plurality of mapping patterns includes a first mapping pattern and a second mapping pattern,
• wherein resource elements used for the DMRS of the second mapping pattern are same as a part of resource elements used for the DMRS of the first mapping pattern, and
• wherein a number of the resource elements used for the DMRS of the first mapping pattern is larger than a number of the resource elements used for the DMRS of the second mapping pattern,
• wherein a density of the DMRS of the first mapping pattern is larger than a density of the DMRS of the second mapping pattern in a time domain.