A terminal apparatus, a base station apparatus, a communication method, an integrated circuit, and a radio communication system are provided that enable a base station apparatus and a terminal apparatus to determine parameters relating to an uplink reference signal and efficiently communicate with each other. A terminal apparatus that transmits a demodulation reference signal, the terminal apparatus comprising: means for receiving a cell-specific parameter used for enabling or disabling a sequence group hopping, means for a user-equipment-specific parameter used for disabling the sequence group hopping, and means for generating a sequence of the demodulation reference signal on the basis of the enabled or disabled sequence group hopping, wherein, in a case that a transmission on the physical uplink shared channel corresponding to a downlink control information format to which CRC parity bits scrambled by a temporary C-RNTI are attached, the sequence group hopping is enabled or disabled on the basis of the cell-specific parameter.