User equipment and communication method

#The present invention relates to a user equipment in a radio communication system.

#Currently, in a 3rd generation partnership project (3GPP), a next generation system, which corresponds to a successor of long term evolution (LTE)-advanced as one of fourth generation radio communication systems and is called 5G, has been examined. In the 5G, three use cases including an extended mobile broadband (eMBB), a massive machine type communication (mMTC), and an ultra reliability and low latency communication (URLLC) are mainly assumed.

#The URLLC is aimed at realization of a radio communication with low latency and high reliability. In the URLLC, as a specific plan for realization of low latency, introduction of a short transmission time interval (TTI) length (also referred to as a subframe length, or a subframe interval), shortening of control latency from packet generation to data transmission, and the like have been examined. In addition, as a specific plan for realization of high reliability in the URLLC, introduction of a coding mode with a low coding rate and a modulation mode for realization of a low bit error rate, utilization of diversity, and the like have been examined.

#FIG. 1 is a configuration diagram of a radio communication system according to an embodiment of the invention;

#FIG. 2 is a configuration diagram of a radio communication system according to the embodiment of the invention;

#FIG. 3 is a view illustrating an operation of switching a carrier in accordance with priority of data in a first embodiment;

#Hereinafter, an embodiment (this embodiment) of the invention will be described with reference to the accompanying drawings. Furthermore, the following embodiment to be described below is illustrative only, and an embodiment to which the invention is applied is not limited to the following embodiment.

#It is assumed that a radio communication system of this embodiment supports at least an LTE communication mode. Accordingly, an existing technology defined in the LTE can be appropriately used in an operation of the radio communication system. However, the existing technology is not limited to the LTE. In addition, it is assumed that “LTE” in this specification has broad meaning including LTE-Advanced, and a mode (for example, 5G) subsequent to the LTE-Advanced unless otherwise stated. In addition, the invention is also applicable to a communication mode other than the LTE.

#FIG. 1 illustrates a configuration diagram of the radio communication system according to this embodiment (common to first to third embodiments). The radio communication system according to this embodiment performs a communication with multi-carriers (a plurality of carriers) by the same configuration as that of dual connectivity (for example, Non-Patent Document 1; hereinafter, referred to as “DC”) in LTE. As illustrated in FIG. 1, the radio communication system includes a user equipment 10, a master base station 20, and a slave base station 30. In the drawing, a base station is described as “BS” for convenience. The BS is an abbreviation of the base station. The master base station 20 corresponds to MeNB of the DC, and the slave base station 30 corresponds to SeNB of the DC. Furthermore, the “master” and the “slave” are terms which are given for convenience of discrimination of two base stations. Furthermore, the master base station 20 may be a plurality of master base stations, and the slave base station 30 may be a plurality of slave base stations.