Method for transmitting or receiving signal in wireless communication system and apparatus for same

A user equipment (UE) for transmitting an uplink signal in a wireless communication system, the UE comprising:

• a receiver;
• a transmitter;
• and
• a processor for receiving, from a base station, information indicating one of a contention based transmission scheme or a contention free based transmission scheme by controlling the receiver, and transmitting uplink data based on a transmission scheme indicated based on the received information by controlling the transmitter,
• wherein based on the indicated transmission scheme being the contention based transmission scheme, the processor transmits, in addition to the uplink data, information for identifying the UE, and the processor prioritizes transmission success of the information for identifying the UE, which is additionally transmitted, over transmission success of the uplink data,
• wherein the UE determines that both the transmission of the uplink data and the transmission of the information for identifying the UE have been successfully performed based on an acknowledge (ACK) signal being received,
• wherein the UE determines that the transmission of the information for identifying the UE has been successfully performed but the transmission of the uplink data has failed, based on a UE-specific negative ACK (NACK) signal being received, and
• wherein the UE determines that both the transmission of the uplink data and the transmission of the information for identifying the UE have failed based on a broadcast NACK signal being received without reception of the ACK signal.

A method for receiving an uplink signal by a base station in a wireless communication system, the method comprising:

• transmitting information indicating one of a contention based transmission scheme or a contention free based transmission scheme;
• attempting to detect uplink data of a user equipment (UE) based on a transmission scheme indicated based on the transmitted information;
• and
• transmitting an acknowledge (ACK) signal or a negative ACK (NACK) signal to the UE in accordance with whether the base station succeeded in detecting the uplink data,
• wherein based on the indicated transmission scheme being the contention based transmission scheme, the base station attempts to detect information for identifying the UE, in addition to the uplink data, and based on the base station succeeding in detecting both the uplink data and the information for identifying the UE, the base station transmits the ACK signal,
• wherein the base station transmits a UE-specific negative ACK (NACK) signal if detection of the information for identifying the UE has been successfully performed but detection of the uplink data has failed, and
• wherein the base station transmits a broadcast NACK signal if detection of the information for identifying the UE has failed.