A method for receiving a narrowband reference signal, NRS, in a wireless communication, the method performed by a narrowband internet of things, NB-IoT, device and being characterized by : receiving information on an NB-IoT operation mode; receiving information on at least one among a plurality of a time division duplex, TDD, special subframe configuration indexes; and receiving the NRS on a orthogonal frequency division multiplexing, OFDM, symbol in a TDD special subframe, based on the at least one TDD special subframe configuration index, wherein the OFDM symbol for receiving the NRS are determined based on the at least one TDD special subframe configuration index, and wherein, based on the information on the NB-IoT operation mode being used for an inband-samePCI mode which informs an in-band deployment and a same physical cell identifier, PCI, a cell-specific reference signal, CRS, is available for the NB-IoT device in the TDD special subframe used for the NRS, wherein the OFDM symbol for receiving the NRS is 3rd symbol in a plurality of OFDM symbols in the TDD special subframe, wherein a number of the plurality of OFDM symbols is 14, wherein, in the NB-IoT operation mode being used for an inband-samePCI mode, a number of the NRS is as same as a number of the CRS, wherein, based on the NB-IoT operation mode being the in-band deployment, the NRS is received when satisfying a specific condition, wherein the specific condition includes whether the TDD special subframe is a valid subframe or not, wherein, in the NB-IoT operation mode being the in-band deployment, the UE assumes that the NRS is always transmitted on a downlink pilot time slot, DwPTS, of a corresponding carrier, wherein, when determining the NRS, all of 12 resource elements, REs, in the 3rd symbol of the TDD special subframe is used, and wherein the NRS is determined based on a Zadoff-Chu sequence based on a NB-IoT cell ID. receiving information on an NB-IoT operation mode; receiving information on at least one among a plurality of a time division duplex, TDD, special subframe configuration indexes; and receiving the NRS on a orthogonal frequency division multiplexing, OFDM, symbol in a TDD special subframe, based on the at least one TDD special subframe configuration index, wherein the OFDM symbol for receiving the NRS are determined based on the at least one TDD special subframe configuration index, and wherein, based on the information on the NB-IoT operation mode being used for an inband-samePCI mode which informs an in-band deployment and a same physical cell identifier, PCI, a cell-specific reference signal, CRS, is available for the NB-IoT device in the TDD special subframe used for the NRS, wherein the OFDM symbol for receiving the NRS is 3rd symbol in a plurality of OFDM symbols in the TDD special subframe, wherein a number of the plurality of OFDM symbols is 14, wherein, in the NB-IoT operation mode being used for an inband-samePCI mode, a number of the NRS is as same as a number of the CRS, wherein, based on the NB-IoT operation mode being the in-band deployment, the NRS is received when satisfying a specific condition, wherein the specific condition includes whether the TDD special subframe is a valid subframe or not, wherein, in the NB-IoT operation mode being the in-band deployment, the UE assumes that the NRS is always transmitted on a downlink pilot time slot, DwPTS, of a corresponding carrier, wherein, when determining the NRS, all of 12 resource elements, REs, in the 3rd symbol of the TDD special subframe is used, and wherein the NRS is determined based on a Zadoff-Chu sequence based on a NB-IoT cell ID. <EOS>