A user equipment (104, 204, 205) comprising: a receiving unit configured to receive, from a base station device (101, 102), a higher layer signal including information for configuring a plurality of parameters X, the receiving unit being configured to receive, from the base station device (101, 102), a reference signal on resource blocks on which a physical downlink shared channel is mapped, a sequence of the reference signal being defined by a pseudo-random sequence c, the pseudo-random sequence c being defined by an equation 1, the Nc in the equation 1 being 1600, the sequence x 2 in the equation 1 being initialized according to an equation 2, the c init in the equation 2 being defined by an equation 3, the n s in the equation 3 being a slot number in a radio frame, the sequence x 1 in the equation 1 being initialized according to an equation 4, wherein the condition A in the equation 3 is that the physical downlink shared channel is decoded based on a detection of a first physical downlink control channel with cyclic redundancy check scrambled by cell radio network temporary identifier, the first physical downlink control channel being with a first downlink control information format and in a common search space, the N ID cell in the equation 3 being a physical layer cell identity, the n SCID in the equation 3 being a scrambling identity, and the condition B in the equation 3 is that the physical downlink shared channel is decoded based on a detection of a second physical downlink control channel with cyclic redundancy check scrambled by cell radio network temporary identifier, the second physical downlink control channel being with a second downlink control information format other than the first downlink control information format and in a user equipment specific search space, the X in the equation 3 being indicated from the plurality of parameters X by downlink control information transmitted on the second physical downlink control channel, the Y in the equation 3 being a scrambling identity. c n = x 1 n + N C + x 2 n + N C mod2 x 1 n + 31 = x 1 n + 3 + x 1 n mod 2 x 2 n + 31 = x 2 n + 3 + x 2 n + 2 + x 2 n + 1 + x 2 n mod2 c init = ∑ i = 0 30 x 2 i ⋅ 2 i c init = { ⌊ n s / 2 ⌋ + 1 ⋅ 2 N ID cell + 1 ⋅ 2 16 + n SCID if condition A ⌊ n s / 2 ⌋ + 1 ⋅ 2 X + 1 ⋅ 2 16 + Y if condition B x 1 0 = 1, x 1 n = 0, n = 1,2,..., 30 a receiving unit configured to receive, from a base station device (101, 102), a higher layer signal including information for configuring a plurality of parameters X, the receiving unit being configured to receive, from the base station device (101, 102), a reference signal on resource blocks on which a physical downlink shared channel is mapped, a sequence of the reference signal being defined by a pseudo-random sequence c, the pseudo-random sequence c being defined by an equation 1, the Nc in the equation 1 being 1600, the sequence x 2 in the equation 1 being initialized according to an equation 2, the c init in the equation 2 being defined by an equation 3, the n s in the equation 3 being a slot number in a radio frame, the sequence x 1 in the equation 1 being initialized according to an equation 4, wherein the condition A in the equation 3 is that the physical downlink shared channel is decoded based on a detection of a first physical downlink control channel with cyclic redundancy check scrambled by cell radio network temporary identifier, the first physical downlink control channel being with a first downlink control information format and in a common search space, the N ID cell in the equation 3 being a physical layer cell identity, the n SCID in the equation 3 being a scrambling identity, and the condition B in the equation 3 is that the physical downlink shared channel is decoded based on a detection of a second physical downlink control channel with cyclic redundancy check scrambled by cell radio network temporary identifier, the second physical downlink control channel being with a second downlink control information format other than the first downlink control information format and in a user equipment specific search space, the X in the equation 3 being indicated from the plurality of parameters X by downlink control information transmitted on the second physical downlink control channel, the Y in the equation 3 being a scrambling identity. c n = x 1 n + N C + x 2 n + N C mod2 x 1 n + 31 = x 1 n + 3 + x 1 n mod 2 x 2 n + 31 = x 2 n + 3 + x 2 n + 2 + x 2 n + 1 + x 2 n mod2 c init = ∑ i = 0 30 x 2 i ⋅ 2 i c init = { ⌊ n s / 2 ⌋ + 1 ⋅ 2 N ID cell + 1 ⋅ 2 16 + n SCID if condition A ⌊ n s / 2 ⌋ + 1 ⋅ 2 X + 1 ⋅ 2 16 + Y if condition B x 1 0 = 1, x 1 n = 0, n = 1,2,..., 30