Method and apparatus for transmitting a random access preamble in a narrow band IoT system supporting time division duplexing

A method for receiving a narrowband physical random access channel (NPRACH) preamble by a base station in a narrowband-Internet of things (NB-IoT) system supporting time division duplexing, the method comprising:

• transmitting, to a base station, configuration information related to an uplink-downlink configuration;
• and
• receiving, from the user equipment, the NPRACH preamble configured by considering the uplink-downlink configuration,
• wherein the NPRACH preamble includes two symbol group sets and the symbol group set includes three contiguous symbol groups, and
• wherein a length of the symbol group set is configured be shorter than a transmission time unit in the NB-IoT system.

A user equipment transmitting a narrowband physical random access channel (NPRACH) preamble in a narrowband-Internet of things (NB-IoT) system supporting time division duplexing, the user equipment comprising:

• a radio frequency (RF) module transmitting and receiving a radio signal;
• and
• a processor controlling the RF module,
• wherein the processor
• receives, from a base station, configuration information related to an uplink-downlink configuration, and
• transmits, to the base station, the NPRACH preamble configured by considering the uplink-downlink configuration,
• wherein the NPRACH preamble includes two symbol group sets and the symbol group set includes three contiguous symbol groups, and
• wherein a length of the symbol group set is configured be shorter than a transmission time unit in the NB-IoT system.