Patent ID: 9491700
Filing Date: 2016-11-08
CPC Classification: H04W,Y02D

Claim Text:
1. A method of transmitting and receiving a frame performed by a first station (STA) that operates in a power save mode in a wireless local area network (WLAN) system, comprising: receiving a traffic indication map (TIM) element including a bitmap sequence, wherein the bitmap sequence includes a first bit indicating that a buffered frame for the first STA exists and a second bit indicating that a buffered frame for a second STA exists; setting a back-off timer for the first STA based on a bit index of the first bit and the second bit, wherein the back-off timer for the first STA is a value of at least one slot time, wherein if the bit index of the first bit is lower than the bit index of the second bit, a value of the back-off timer for the first STA is higher than a value of a back-off timer for the second STA, wherein if the bit index of the first bit is higher than the bit index of the second bit, a value of the back-off timer for the first STA is lower than a value of a back-off timer for the second STA; acquiring a channel access authority based on at least one slot time, wherein each slot time is a time when a channel is kept in an idle state for a channel access of the first STA; transmitting a PS (power save)-poll frame requesting a transmission of the buffered frame for the first STA to an access point (AP); and receiving a response frame from the AP in response to the PS-poll frame, wherein a length of the each slot time is set to be larger than a transmission time of the PS-poll frame.