Description:SOFT COPY ATTACHED , Claims:We Claim:

1. A communication system comprising:
a user apparatus; and
at least one base station configured to wirelessly communicate with the user apparatus using a beam, wherein
the user apparatus determines a communication quality of a channel state information reference signal (CSI-RS) transmitted from the base station.

2. The communication system according to Claim 1, wherein the user apparatus determines the communication quality based on a comparison of a signal-to-noise ratio (SNR) indicating the communication quality and a threshold.

3. The communication system according to Claim 2, wherein the user apparatus determines the communication quality based on whether or not the SNR is below the threshold.

4. The communication system according to any of Claims 1 to 3, wherein the user apparatus transmits a beam disappearance notification based on a determination result of the communication quality.

5. The communication system according to Claim 4, wherein
the at least one base station includes a master base station and a secondary base station, and
the user apparatus transmits, to the master base station, the beam disappearance notification related to the secondary base station communicating with the user apparatus.

6. The communication system according to Claim 5, wherein the master base station transmits, to the secondary base station, an indication corresponding to the beam disappearance notification received from the user apparatus.

7. The communication system according to Claim 4, wherein the user apparatus transmits the beam disappearance notification using a physical uplink shared channel (PUSCH) or a physical uplink control channel (PUCCH).

8. The communication system according to Claim 4, wherein the user apparatus transmits the beam disappearance notification using a random access (RA).

9. The communication system according to Claim 4, wherein the user apparatus initiates beam redetection after transmitting the beam disappearance notification.

10. A user apparatus in a communication system comprising the user apparatus and at least one base station configured to wirelessly communicate with the user apparatus using a beam, wherein
the user apparatus determines a communication quality of a channel state information reference signal (CSI-RS) transmitted from the base station.

11. A base station in a communication system comprising a user apparatus and at least one base station configured to wirelessly communicate with the user apparatus using a beam, wherein
the base station transmits a channel state information reference signal (CSI-RS) that is used for determining a communication quality at the user apparatus.