Method and device for performing backoff and channel access on antenna ports distributed in das in wireless lan system

A receiving station (STA) in a wireless local area network (WLAN) system, the receiving STA comprising:

• a memory;
• a transceiver;
• and
• a processor being operatively connected to the memory and the transceiver,
• wherein the processor is configured to:
• check whether at least one antenna port among a plurality of antenna ports is idle;
• perform backoff for the at least one antenna port based on the at least one antenna port being idle;
• perform channel access for a first channel that is commonly idle in the at least one antenna port based on a counter of the backoff becoming 0;
• and
• receive a Physical Protocol Data Unit (PPDU) from a transmitting STA through the first channel,
• wherein the transmitting STA operates in a system in which the plurality of antenna ports are distributed,
• wherein a first primary 20 MHz channel is set for the plurality of antenna ports,
• wherein the first primary 20 MHz channel is a primary 20 MHz channel that exists within one Basic Service Set (BSS), and
• wherein whether the at least one antenna port is idle is determined based on whether the first primary 20 MHz channel of the at least one antenna port is idle.

A method in a wireless local area network (WLAN) system, the method comprising:

• checking, by a transmitting station (STA), whether at least one antenna port among a plurality of antenna ports is idle;
• performing, by the transmitting STA, backoff for the at least one antenna port based on the at least one antenna port being idle;
• performing, by the transmitting STA, channel access for a first channel that is commonly idle in the at least one antenna port based on a counter of the backoff becoming 0;
• and
• transmitting, by the transmitting STA, a Physical Protocol Data Unit (PPDU) to a receiving STA through the first channel,
• wherein the transmitting STA operates in a system in which the plurality of antenna ports are distributed,
• wherein a first primary 20 MHz channel is set for the plurality of antenna ports,
• wherein the first primary 20 MHz channel is a primary 20 MHz channel that exists within one Basic Service Set (BSS), and
• wherein whether the at least one antenna port is idle is determined based on whether the first primary 20 MHz channel of the at least one antenna port is idle.