Power reduction mode operation method in wireless LAN system supporting channel for downlink, and apparatus therefor

1. A method of operating in a power save mode by a Station (STA) in a Wireless Local Area Network (WLAN) system, the method comprising;

entering the power save mode after performing an association procedure with an Access Point (AP);

receiving a Traffic Indication Map (TIM) from the AP in a listening interval configured for the power save mode;

if the TIM indicates the presence of data to be received from the AP, transmitting a Power Save Poll (PS-Poll) signal to the AP;

receiving a response signal to the PS-Poll signal from the AP; and

receiving data from the AP,

wherein the TIM reception, the transmission of the PS-Poll signal, and the data reception are performed on a downlink oriented channel or a normal channel distinguished from the downlink oriented channel, and the STA preliminarily acquires information indicating on which channel between the downlink oriented channel and the normal channel the TIM reception, the transmission of the PS-Poll signal, and the data reception are performed.

2. The method according to claim 1 , wherein the downlink oriented channel is a channel configured for the AP to transmit data to STAs associated with the AP, and the associated STAs are not allowed to transmit data to the AP on the downlink oriented channel.

3. The method according to claim 1 , wherein the STA receives the TIM on the normal channel, and monitors the normal channel in every listening interval during operation in the power save mode.

4. The method according to claim 3 , wherein the PS-Poll signal is transmitted on the normal channel, and the response signal to the PS-Poll signal includes information indicating whether the data is to be received from the AP on the downlink oriented channel or the normal channel.

5. The method according to claim 3 , further comprising negotiating with the AP about whether the data reception is performed on the downlink oriented channel or the normal channel,

wherein the data is received from the AP on the negotiated channel.

6. The method according to claim 1 , wherein the STA receives the TIM on the downlink oriented channel, and monitors the downlink oriented channel in every listening interval during operation in the power save mode.

7. The method according to claim 6 , wherein if the TIM received on the downlink oriented channel indicates the presence of data to be transmitted to the STA, the STA switches to the normal channel and transmits the PS-Poll signal on the normal channel.

8. The method according to claim 7 , wherein upon receipt of a response signal to the PS-Poll signal, the STA switches to the downlink oriented channel and receives data from the AP on the downlink oriented channel.

9. The method according to claim 6 , wherein if the TIM received on the downlink oriented channel indicates the presence of data to be transmitted to the STA, the STA transmits the PS-Poll signal on the downlink oriented channel.

10. The method according to claim 9 , wherein the AP transmits configuration information about a PS-Poll signal transmission interval to the STA, and the STA transmits the PS-Poll signal during the PS-Poll signal transmission interval.

11. The method according to claim 6 , wherein if the TIM received on the downlink oriented channel indicates the presence of data to be transmitted to the STA, the STA transmits the PS poll signal on the downlink oriented channel or the normal channel according to negotiation during performing the association procedure with the AP.

12. A method of supporting a power save mode of a Station (STA) by an Access Point (AP) in a Wireless Local Area Network (WLAN) system, the method comprising;

performing an association procedure with one or more STAs;

receiving a signal indicating entrance into the power save mode from a first STA among the one or more STAs;

if there is data to be transmitted to the first STA, transmitting a Traffic Indication Map (TIM) to the first STA in a listening interval configured for the power save mode;

receiving a Power Save Poll (PS-Poll) signal from the first STA;

transmitting a response signal to the PS-Poll signal to the first STA; and

transmitting data to the first STA,

wherein the TIM transmission, the reception of the PS-Poll signal, and the data transmission are performed on a downlink oriented channel or a normal channel distinguished from the downlink oriented channel, and the AP preliminarily acquires information indicating on which channel between the downlink oriented channel and the normal channel the TIM transmission, the reception of the PS-Poll signal, and the data transmission are performed.

13. A Station (STA) supporting a power save mode in a Wireless Local Area Network (WLAN) system, the STA comprising;

a transceiver configured to transmit and receive a signal to and from an Access Point (AP) on a downlink oriented channel or a normal channel distinguished from the downlink oriented channel; and

a processor connected to the transceiver and configured to control operation of the transceiver,

wherein the processor is configured to enter the power save mode after performing an association procedure, and if the transceiver receives a Traffic Indication Map (TIM) from the AP in a listening interval configured for the power save mode and the TIM indicates the presence of data to be received from the AP, to transmit a Power Save Poll (PS-Poll) signal to the AP, receive a response signal to the PS-Poll signal from the AP, and receive data from the AP, through the transceiver,

wherein the TIM reception, the transmission of the PS-Poll signal, and the data reception are performed on a downlink oriented channel or a normal channel distinguished from the downlink oriented channel, and

wherein the processor preliminarily acquires information indicating on which channel between the downlink oriented channel and the normal channel the TIM reception, the transmission of the PS-Poll signal, and the data reception are performed.

14. An Access Point (AP) for supporting a power save mode of a Station (STA) in a Wireless Local Area Network (WLAN) system, the AP comprising;

a transceiver configured to transmit and receive a signal to and from one or more STAs on a downlink oriented channel or a normal channel distinguished from the downlink oriented channel; and

a processor connected to the transceiver and configured to control operation of the transceiver,

wherein the processor is configured to perform an association procedure with the one or more STAs, to receive a signal indicating entrance into the power save mode from a first STA among the one or more STAs through the transceiver and, if there is data to be transmitted to the first STA, to transmit a Traffic Indication Map (TIM) to the first STA in a listening interval configured for the power save mode, receive a Power Save Poll (PS-Poll) signal from the first STA, transmit a response signal to the PS-Poll signal to the first STA, and transmit data to the first STA, through the transceiver,

wherein the TIM transmission, the reception of the PS-Poll signal, and the data transmission are performed on a downlink oriented channel or a normal channel distinguished from the downlink oriented channel, and

wherein the processor preliminarily acquires information indicating on which channel between the downlink oriented channel and the normal channel the TIM transmission, the reception of the PS-Poll signal, and the data transmission are performed.