Method and device for transmitting NPRACH preamble in narrowband IoT system supporting frame structure type 2

A user equipment (UE) configured to transmit narrowband physical random access channel (NPRACH) preamble in a narrow band (NB)-Internet of things (IoT) system supporting a frame structure type 2, the UE comprising:

• a radio frequency (RF) module configured to transmit and receive a radio signal;
• and
• a processor configured to control the RF module,
• wherein the processor is configured to:
• receive, from a base station, first information for a NPRACH configuration;
• and
• transmit, to the base station, the NPRACH preamble based on the received first information,
• wherein the NPRACH preamble is repeatedly transmitted as a plurality of preamble repetition units, with each preamble repetition unit consisting of a plurality of symbol groups, and with each symbol group consisting of one cyclic prefix (CP) and at least one symbol,
• wherein not all symbols groups comprising the each preamble repetition unit are contiguous in time,
• wherein a subcarrier spacing for the NPRACH preamble is configured as 3.75 kHz,
• wherein (i) a number of symbols included in each symbol group and (ii) a length of the CP included in each symbol group depend on an uplink-downlink configuration that is related to controlling in which subframes uplink or downlink transmissions take place in a frame, and
• wherein the number of symbols in each symbol group is less than 5, and the length of the CP in each symbol group is shorter than a length of one symbol of each symbol group.