Base station and base station communication method

1. A base station, comprising:

a processor that assigns a common downlink reference signal to a plurality of beams based on a Doppler shift estimated using an uplink reference signal; and

a transmitter that transmits the common downlink reference signal in the plurality of beams,

wherein the processor assigns a separate downlink reference signal different from the common downlink reference signal to one or more beams different from the plurality of beams.

2. The base station according to claim 1 , wherein the plurality of beams include at least one of a plurality of beams transmitted by another base station.

3. The base station according to claim 1 , wherein the transmitter code-multiplexes, in a time axis, the common downlink reference signal transmitted a plurality of times.

4. The base station according to claim 1 , wherein the processor

configures, to a second periodicity, a transmission periodicity of the common downlink reference signal transmitted using the plurality of beams, the second periodicity being longer than a first periodicity, and

assigns an additional downlink reference signal used for channel state measurement to a time resource for which mapping of the common downlink reference signal is scheduled in a case of the first periodicity.

5. A communication method for a base station, the communication method comprising the following performed by the base station:

assigning a common downlink reference signal to a plurality of beams based on a Doppler shift estimated using an uplink reference signal;

assigning a separate downlink reference signal different from the common downlink reference signal to one or more beams different from the plurality of beams; and

transmitting the common downlink reference signal in the plurality of beams.