A terminal apparatus for communicating with a base station apparatus, the terminal apparatus comprising: a reception unit configured to receive a configuration of an initial uplink, UL, bandwidth part, BWP, and a configuration of an additional UL BWP via a radio resource control, RRC, message and receive a random access response, RAR, message including an RAR UL grant in a contention-based random access procedure; a processing unit configured to switch an active UL BWP between the initial UL BWP and the additional UL BWP such that one of the initial UL BWP and the additional UL BWP is activated as the active UL BWP and the other one is deactivated; and a transmission unit configured to transmit a physical uplink shared channel, PUSCH, in the active UL BWP, wherein, the PUSCH is scheduled by using the RAR UL grant, the RAR UL grant comprising a PUSCH frequency resource allocation field with a fixed bit size, the processing unit is further configured to truncate bits from the PUSCH frequency resource allocation field for truncating the PUSCH frequency resource allocation field or to insert bits into the PUSCH frequency resource allocation field for expanding the PUSCH frequency resource allocation field, and to interpret the truncated PUSCH frequency resource allocation field or the expanded PUSCH frequency resource allocation field as a field indicating frequency resource allocation of the PUSCH, in a case that the initial UL BWP is the active UL BWP, to truncate bits from the PUSCH frequency resource allocation field or to insert bits into the PUSCH frequency resource allocation field is done by using a size of the initial UL BWP, and in a case that the additional UL BWP is the active UL BWP, to truncate bits from the PUSCH frequency resource allocation field or to insert bits into the PUSCH frequency resource allocation field is done by using the size of the initial UL BWP; wherein the size of the initial UL BWP is the number of resource blocks indicating the bandwidth of the initial UL BWP. a reception unit configured to receive a configuration of an initial uplink, UL, bandwidth part, BWP, and a configuration of an additional UL BWP via a radio resource control, RRC, message and receive a random access response, RAR, message including an RAR UL grant in a contention-based random access procedure; a processing unit configured to switch an active UL BWP between the initial UL BWP and the additional UL BWP such that one of the initial UL BWP and the additional UL BWP is activated as the active UL BWP and the other one is deactivated; and a transmission unit configured to transmit a physical uplink shared channel, PUSCH, in the active UL BWP, wherein, the PUSCH is scheduled by using the RAR UL grant, the RAR UL grant comprising a PUSCH frequency resource allocation field with a fixed bit size, the processing unit is further configured to truncate bits from the PUSCH frequency resource allocation field for truncating the PUSCH frequency resource allocation field or to insert bits into the PUSCH frequency resource allocation field for expanding the PUSCH frequency resource allocation field, and to interpret the truncated PUSCH frequency resource allocation field or the expanded PUSCH frequency resource allocation field as a field indicating frequency resource allocation of the PUSCH, in a case that the initial UL BWP is the active UL BWP, to truncate bits from the PUSCH frequency resource allocation field or to insert bits into the PUSCH frequency resource allocation field is done by using a size of the initial UL BWP, and in a case that the additional UL BWP is the active UL BWP, to truncate bits from the PUSCH frequency resource allocation field or to insert bits into the PUSCH frequency resource allocation field is done by using the size of the initial UL BWP; wherein the size of the initial UL BWP is the number of resource blocks indicating the bandwidth of the initial UL BWP.