Method and apparatus for transmitting and receiving power save-polling frame and response frame in wireless LAN system
A method and apparatus for transmitting and receiving a power save-polling (PS-Poll) frame and response frame in a wireless LAN (WLAN) system are disclosed. The method for transmitting a frame by a station (STA) in a wireless LAN (WLAN) system includes awakening at a predetermined time, and transmitting a Power Save (PS)-Poll frame to an access point (AP); and receiving information in response to the PS-Poll frame from the access point (AP), wherein information indicating an access category (AC) of the PS-Poll frame is provided from the access point (AP) to the station (STA).
1. A method for transmitting a frame by a first type station (STA) in a wireless LAN (WLAN) system, the method comprising:
receiving an information element from an access point (AP),
wherein the information element includes a Power Save (PS)-Poll Access Category (AC) field indicating an AC of a PS-Poll frame to be transmitted by the first type STA,
wherein the PS-Poll AC field of the information element is reserved for a second type STA,
wherein the first type STA is a STA to which at least one of a non-TIM (Traffic Indication Map) operation and a RAW (Restricted Access Window) operation can be applied,
wherein the second type STA is a STA to which the non-TIM operation and the RAW operation cannot be applied,
wherein the non-TIM operation is an operation for the first type STA to:
not listen for a TIM element from the AP, and
transmit a PS-Poll frame to the AP,
wherein the RAW operation is an operation for the AP to allocate a RAW to a limited number of the first type STAs to spread an uplink access of the first type STA,
wherein information on the PS-Poll AC field can indicate an AC other than an Access Category-Best Effort (AC_BE) while a transmission of a PS-Poll frame by the second type STA is predetermined as using only the AC_BE to reduce collision probability;
transmitting, by the first type STA, the PS-Poll frame to the AP according to information on the PS-Poll AC field; and
receiving a response in response to the PS-Poll frame from the AP by the first type STA.
2. The method according to claim 1 , wherein the information on the PS-Poll AC field includes an AC field applied to the PS-Poll frame to be transmitted within the RAW.
3. The method according to claim 2 , wherein the AC field is used for the AP to inform the first type STA of an access category for transmitting the PS-Poll frame in the RAW.
4. The method according to claim 1 , wherein the information element is included in a beacon frame.
5. The method according to claim 1 , wherein the PS-Poll AC field is two bits long.
6. The method according to claim 1 , wherein the transmission of the PS-Poll frame by the first type STA is performed with a backoff procedure for accessing a wireless medium in the RAW using the access category corresponding to a specific value set by the PS-Poll AC field.
7. The method according to claim 1 , wherein the first type STA is a non-TIM STA.
8. A method for supporting transmission of a first type station (STA) by an access point (AP) in a wireless LAN (WLAN) system, the method comprising:
transmitting an information element by the AP,
wherein the information element includes a Power Save (PS)-Poll Access Category (AC) field indicating an AC of a PS-Poll frame to be transmitted by the first type STA,
wherein the PS-Poll AC field of the information element is reserved for a second type STA,
wherein the first type STA is a STA to which at least one of a non-TIM (Traffic Indication Map) operation and a RAW (Restricted Access Window) operation can be applied,
wherein the second type STA is a STA to which the non-TIM operation and the RAW operation cannot be applied,
wherein the non-TIM operation is an operation for the first type STA to:
not listen for a TIM element from the AP, and
transmit a PS-Poll frame to the AP,
wherein the RAW operation is an operation for the AP to allocate a RAW to a limited number of the first type STAs to spread an uplink access of the first type STA,
wherein information on the PS-Poll AC field can indicate an AC other than an Access Category-Best Effort (AC_BE) while a transmission of a PS-Poll frame by the second type STA is predetermined as using only the AC_BE to reduce collision probability;
receiving the PS-Poll frame from the first type STA according to information on the PS-Poll AC field; and
transmitting a response in response to the PS-Poll frame to the first type STA,
wherein information indicating an Access Category (AC) of the PS-Poll frame to be transmitted by the first type STA within the RAW is provided from the AP to the first type STA, the first type STA being a STA of which transmission is restricted to a Restricted Access Window (RAW) allocated by the AP.
9. A first type station (STA) device for transmitting a frame in a wireless LAN (WLAN) system, the first type STA comprising:
a transceiver; and
a processor configured to:
receive, using the transceiver, an information element from an access point (AP);
transmit, using the transceiver, a Power Save (PS)-Poll frame to an access point (AP); and
receive, using the transceiver, a response in response to the PS-Poll frame from the AP,
wherein the information element includes a PS-Poll Access Category (AC) field indicating an AC of the PS-Poll frame to be transmitted by the first type STA,
wherein the PS-Poll AC field of the information element is reserved for a second type STA,
wherein the first type STA is a STA to which at least one of a non-TIM (Traffic Indication Map) operation and a RAW (Restricted Access Window) operation can be applied,
wherein the second type STA is a STA to which the non-TIM operation and the RAW operation cannot be applied,
wherein the non-TIM operation is an operation for the first type STA to:
not listen for a TIM element from the AP, and
transmit a PS-Poll frame to the AP,
wherein the RAW operation is an operation for the AP to allocate a RAW to a limited number of the first type STAs to spread an uplink access of the first type STA,
wherein information on the PS-Poll AC field can indicate an AC other than an Access Category-Best Effort (AC_BE) while a transmission of a PS-Poll frame by the second type STA is predetermined as using only the AC_BE to reduce collision probability.
10. An access point (AP) device for supporting transmission of a first type station (STA) in a wireless LAN (WLAN) system, the AP comprising:
a transceiver; and
a processor configured to:
transmit, using the transceiver, an information element;
receive, using the transceiver, a Power Save (PS)-Poll frame from the first type STA; and
transmit, using the transceiver, a response information in response to the PS-Poll frame to the first type STA,
wherein the information element includes a PS-Poll Access Category (AC) field indicating an AC of a PS-Poll frame to be transmitted by the first type STA,
wherein the PS-Poll AC field of the information element is reserved for a second type STA,
wherein the first type STA is a STA to which at least one of a non-TIM (Traffic Indication Map) operation and a RAW (Restricted Access Window) operation can be applied,
wherein the second type STA is a STA to which the non-TIM operation and the RAW operation cannot be applied,
wherein the non-TIM operation is an operation for the first type STA to:
not listen for a TIM element from the AP, and
transmit a PS-Poll frame to the AP,
wherein the RAW operation is an operation for the AP to allocate a RAW to a limited number of the first type STAs to spread an uplink access of the first type STA,
wherein information on the PS-Poll AC field can indicate an AC other than an Access Category-Best Effort (AC_BE) while a transmission of a PS-Poll frame by the second type STA is predetermined as using only the AC_BE to reduce collision probability.