KR20200006006A - Method and apparatus for low power communication in communication system - Google Patents

Abstract

Disclosed are a method and apparatus for low-power communication in a communication system. A low-power station includes: a processor; a memory storing at least one command executed by the processor; a receiver receiving a WUR PPDU in accordance with the command; and a transceiver transceiving a legacy PPDU in accordance with the command. The receiver receives a WUR wakeup frame from an access point in on-duration in a WUR duty cycle section. The processor transmits a first signal requesting a wakeup to the transceiver. The transceiver is executed to transition from a sleep state to a wakeup state in a TWT set between the access point and the low-power station. Therefore, the performance of a communication system can be improved.

Description

METHOD AND APPARATUS FOR LOW POWER COMMUNICATION IN COMMUNICATION SYSTEM}

The present invention relates to a wireless local area network (WLAN) technology, and more particularly, to a low power communication technology in a wireless LAN.

With the development of information and communication technology, various wireless communication technologies are being developed. Among these, wireless local area networks (WLANs) are based on radio frequency technology and use portable terminals such as smartphones, tablet PCs, laptop computers, etc. It is a technology that allows wireless access to the Internet in the service area.

The standard for WLAN technology is being developed as an Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. The WLAN technology according to the IEEE 802.11a standard operates based on orthogonal frequency division multiplexing (OFDM), and may provide a transmission rate of up to 54 Mbps in a 5 GHz band. The WLAN technology according to the IEEE 802.11b standard operates based on a direct sequence spread spectrum (DSSS) scheme and can provide a transmission rate of up to 11 Mbps in the 2.4 GHz band. The WLAN technology based on the IEEE 802.11g standard operates based on the OFDM scheme or the DSSS scheme and may provide a transmission rate of up to 54 Mbps in the 2.4 GHz band.

The WLAN technology according to the IEEE 802.11n standard operates in the 2.4 GHz band and the 5 GHz band based on the OFDM scheme. When the multiple input multiple output (MIMO) -OFDM scheme is used, up to four spatial streams are used. It can provide a transfer rate of 300 Mbps. Wireless LAN technology according to the IEEE 802.11n standard can support a channel bandwidth (channel bandwidth) up to 40MHz, in this case can provide a transmission rate of up to 600Mbps.

As the spread of the WLAN is activated and applications using the same are diversified, there is an increasing need for a new WLAN technology that supports higher throughput than the existing WLAN technology. Very high throughput (VHT) WLAN technology is proposed to support data processing speed of 1Gbps or more. Among them, the WLAN technology according to the IEEE 802.11ac standard is a technology for providing an ultra high throughput in the band below 6GHz, the WLAN technology according to the IEEE 802.11ad standard is a technology for providing an ultra high throughput in the 60GHz band. In addition, the WLAN technology according to the IEEE 802.11ax standard aims to improve frequency efficiency in a dense environment.

Since a communication node (for example, an access point (AP), a station (STA), etc.) supporting the WLAN technology operates depending on a battery, a low power operation method will be required to operate for a long time. To support low power operation, the communication node may include a receiver for low power operation, a transceiver for basic operation according to IEEE 802.11, and the like. In order to perform the low power operation during the down time of the downlink signal indicating the presence or absence of the received packet, the receiver for the low power operation may operate in the wake-up state, and the transceiver may operate in the sleep state. In this case, low power communication methods, linkage methods with low power operation of the existing wireless LAN using a transceiver, and detailed communication methods in a multi-user environment are needed.

An object of the present invention for solving the above problems relates to a low power communication method and apparatus based on a duty cycle (TWC) operation and a target wake time (TWT) operation in a WLAN.

According to a first embodiment of the present invention for achieving the above object, a low power station includes a processor, a memory in which one or more instructions executed by the processor are stored, a receiver receiving a WUR PPDU according to the one or more instructions, and the one And a transceiver configured to transmit and receive a legacy PPDU according to the above instructions, wherein the receiver receives a WUR wakeup frame from an access point in on duration within a WUR duty cycle period, and when the WUR wakeup frame is received, the processor Sends a first signal to the transceiver requesting a wakeup, and when the first signal is received, the transceiver is executed to transition from a sleep state to a wakeup state at a TWT established between the access point and the low power station. .

Here, the one or more instructions may be further executed to send first information to the access point indicating that the low power station supports a TWT function.

Wherein the one or more instructions may be further executed to transmit to the access point second information requesting the low power station to perform a TWT operation, the second information being used for a WUR mode between the access point and the low power station. May be sent in the negotiation procedure.

Here, the one or more instructions may be further executed such that the transceiver maintains the wake up state during a TWT SP established between the access point and the low power station.

Here, the TWT and the TWT SP may be set in a negotiation procedure for the WUR mode between the access point and the low power station.

Wherein the one or more instructions are further executed such that the transceiver transmits and receives the legacy PPDU with the access point during the TWT SP, and wherein the transceiver transitions from the wake up state to the sleep state when the TWT SP terminates. Can be.

Here, the WUR wakeup frame may be received from the TWT before the wakeup delay time of the transceiver.

Here, the legacy PPDU may be a non-HT PPDU, a HT PPDU, a VHT PPDU, or a HE PPDU.

Here, the WUR wakeup frame may be used to wake up a plurality of low power stations, and may include an ID of each of the plurality of low power stations.

Here, the MAC header of the WUR wakeup frame may further include information indicating the number of the plurality of low power stations, and the ID of each of the plurality of low power stations may be included in a frame body of the WUR wakeup frame. have.

According to a second embodiment of the present invention for achieving the above object, a low power station includes a processor, a memory in which one or more instructions executed by the processor are stored, a receiver receiving a WUR PPDU according to the one or more instructions), and the A transceiver that transmits and receives a legacy PPDU in accordance with one or more instructions, the processor sends a first signal to the transceiver requesting wakeup from a TWT established between the access point and the low power station, before a wakeup delay time; When the first signal is received, the transceiver transitions from a sleep state to a wake up state at the TWT, and the transceiver is executed to maintain the wake up state during a TWT SP established between the access point and the low power station. .

Here, the one or more instructions may be further executed to send first information to the access point indicating that the low power station supports a TWT function.

Wherein the one or more instructions may be further executed to transmit to the access point second information requesting the low power station to perform a TWT operation, the second information being used for a WUR mode between the access point and the low power station. May be sent in the negotiation procedure.

Here, the TWT and the TWT SP may be set in a negotiation procedure for the WUR mode between the access point and the low power station.

Here, the one or more instructions may allow the transceiver to transmit and receive the access point and the legacy PPDU during the TWT SP, and to cause the transceiver to transition from the wake up state to the sleep state when the TWT SP is terminated. Can be executed further.

Here, the WUR wakeup frame may be used to wake up a plurality of low power stations, the MAC header of the WUR wakeup frame may include information indicating the number of the plurality of low power stations, and the WUR wakeup The frame body of the up frame may include an ID of each of the plurality of low power stations.

In accordance with a third aspect of the present invention, there is provided a method of operating an access point, the method comprising: receiving a WUR mode request frame including first information requesting to perform a TWT operation from a low power station; Transmitting a WUR mode response frame to the low power station, wherein the WUR mode response frame includes second information indicating that execution of the signal is approved, and transmitting a WUR wake up frame to the low power station before a wake up delay time of the low power station from TWT. Steps.

Here, the WUR mode response frame may further include third information indicating the TWT and fourth information indicating a TWT service period (SP).

Here, the operation method of the access point may further include transmitting and receiving a legacy PPDU with the low power station during the TWT SP, the legacy PPDU may be a non-HT PPDU, HT PPDU, VHT PPDU, or HE PPDU. .

Here, the WUR wakeup frame may be used to wake up a plurality of low power stations, the MAC header of the WUR wakeup frame may include information indicating the number of the plurality of low power stations, and the WUR wakeup The frame body of the up frame may include an ID of each of the plurality of low power stations.

According to the present invention, a target wake time (TWT) and a TWT service period (SP) may be set between the access point and the low power station. In this case, the primary connectivity radio (PCR) of the low power station may transition from the sleep state to the wake up state in the TWT within the WUR duty cycle period and maintain the wake up state during the TWT SP. To support TWT operation, the access point may transmit a wake-up radio (WUR) wakeup signal from the TWT before the wakeup delay time. Therefore, power consumption may be reduced in a WLAN-based communication system.

In addition, a multi-user (MU) WUR wakeup frame may be introduced in a WLAN-based communication system. In this case, the access point may wake up a plurality of low power stations by sending one MU WUR wake up frame. Therefore, the performance of the WLAN-based communication system can be improved.

1 is a conceptual diagram illustrating a first embodiment of a WLAN-based communication system.
2 is a block diagram illustrating a first embodiment of a communication node belonging to a WLAN-based communication system.
3 is a timing diagram showing a first embodiment of a method of operating a communication node based on EDCA.
4 is a conceptual diagram illustrating a second embodiment of a WLAN-based communication system.
5 is a block diagram illustrating a first embodiment of a low power station in a WLAN based communication system.
6 is a block diagram illustrating a second embodiment of a low power station in a WLAN based communication system.
7 is a conceptual diagram illustrating a first embodiment of a channel configuration in a WLAN-based communication system.
8 is a timing diagram illustrating a first embodiment of a method of operating a communication node in a WLAN-based communication system.
9 is a block diagram illustrating a first embodiment of a WUR wakeup frame in a WLAN-based communication system.
FIG. 10 is a block diagram illustrating a second embodiment of a WUR wakeup frame in a WLAN-based communication system.
11 is a timing diagram illustrating a second embodiment of a method of operating a communication node in a WLAN-based communication system.
12 is a timing diagram illustrating a third embodiment of a method of operating a communication node in a WLAN-based communication system.
FIG. 13 is a timing diagram illustrating a fourth embodiment of a method of operating a communication node in a WLAN-based communication system.
FIG. 14 is a timing diagram illustrating a fifth embodiment of a method of operating a communication node in a WLAN-based communication system.
15 is a timing diagram illustrating a sixth embodiment of a method of operating a communication node in a WLAN-based communication system.
FIG. 16 is a timing diagram illustrating a seventh embodiment of a method of operating a communication node in a WLAN-based communication system.
17 is a block diagram illustrating a first frame in a WLAN-based communication system.
18 is a block diagram illustrating a first embodiment of a WUR mode request frame in a WLAN-based communication system.
19 is a timing diagram illustrating a first embodiment of a low power communication operation according to a TWT function in a WLAN based communication system.
20 is a timing diagram illustrating a second embodiment of a low power communication operation according to a TWT function in a WLAN-based communication system.
21 is a block diagram illustrating a first embodiment of a WUR frame in a WLAN-based communication system.
FIG. 22 is a block diagram illustrating a first embodiment of a WUR capability information field in a WLAN based communication system.
FIG. 23 is a block diagram illustrating a first embodiment of an MU WUR wakeup frame in a WLAN-based communication system.

As the present invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and / or includes a combination of a plurality of related items or any item of a plurality of related items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. In the following description of the present invention, the same reference numerals are used for the same elements in the drawings and redundant descriptions of the same elements will be omitted.

Embodiments described in the specification may be applied to a communication system (for example, a wireless local area network (WLAN) based communication system) according to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. In addition, the embodiments described in the specification can be applied to other communication systems as well as communication systems according to the IEEE 802.11 standard. For example, the embodiments described in the specification may include a wireless personal area network (WPAN) based communication system, a wireless body area network (WBAN) based communication system, and a 4G communication system (eg, long term evloution (LTE) based). Communication system, LTE-A (advanced) based communication system), 5G communication system (for example, a new radio (NR) communication system) and the like.

In a WLAN-based communication system, a STA (station) is a physical access control (MAC) layer function defined in the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard and a physical medium for a wireless medium. ) May indicate a communication node performing a function of a layer. STA may be classified into an access point (AP) STA and a non-AP STA. An AP STA may simply be referred to as an access point and a non-AP STA may simply be referred to as a station. In addition, the access point may be a base station (BS), a node B (node B), an advanced node B (evolved node B), a relay, a radio remote head (RRH), a transmission and reception point (TRP), or the like. May be referred to. A station may be referred to as a terminal, a wireless transmit / receive unit (WTRU), a user equipment (UE), a device, or the like, and may be a smart phone, a tablet PC, a laptop computer, or a laptop computer. computer, sensor device, or the like.

1 is a conceptual diagram illustrating a first embodiment of a WLAN-based communication system.

Referring to FIG. 1, a WLAN-based communication system according to the IEEE 802.11 standard may include at least one basic service set (BSS). The BSS may indicate a set of communication nodes (eg, AP # 1-2, STA # 1-6, etc.). BSS can be classified into Infrastructure BSS (Independent BSS) and Independent BSS (IBSS). Here, BSS # 1-2 may be an infrastructure BSS, and BSS # 3 may be an IBSS.

The BSS # 1 may include a station # 1, an access point # 1 connected to a distribution system, and the like. In addition, the BSS # 1 may further include a distribution system. In BSS # 1, communication between station # 1 and access point # 1 may be performed based on the IEEE 802.11 standard. BSS # 2 may include station # 2, station # 3, access point # 2 coupled to a distribution system, and the like. In addition, BSS # 2 may further include a distribution system. In BSS # 2, communication between station # 2 and access point # 2, communication between station # 3 and access point # 2, etc. may be performed based on the IEEE 802.11 standard. Communication between stations (eg, STA # 1-3) in BSS # 1 or BSS # 2 may be performed through an access point (eg, AP # 1-2). However, when a direct link is established between stations (eg, STA # 1-3), direct communication between stations (eg, STA # 1-3) may be performed.

BSS # 3 may be an IBSS operating in ad-hoc mode. There may not be an access point, which is an entity that performs management functions, in BSS # 3. The stations STA # 4-6 in BSS # 3 may be managed based on a distributed manner. Since the connection from the BSS # 3 to the distribution system is not allowed, the stations STA # 4-6 can form a self-contained network.

A plurality of BSSs (eg, BSS # 1-2) may be interconnected through a distribution system. A plurality of BSSs connected through a distribution system may be referred to as an extended service set (ESS). Communication nodes included in the ESS (eg, AP # 1-2 and STA # 1-3) may communicate with each other, and stations (eg, STA # 1-3) may seamlessly communicate in the same ESS. While moving between BSSs (eg, BSS # 1-2).

A communication node (eg, an access point, a station, etc.) belonging to a WLAN based communication system may be configured as follows.

2 is a block diagram illustrating a first embodiment of a communication node belonging to a WLAN-based communication system.

2, a communication node 200 includes a baseband processor 210, a transceiver 220, an antenna 230, a memory 240, an input interface unit 250, and an output interface unit 260. And the like. The baseband processor 210 may perform baseband related signal processing and may include a MAC processor 211 and a PHY processor 212. The MAC processor 211 may perform the functions of the MAC layer defined in the IEEE 802.11 standard, and the PHY processor 212 may perform the functions of the PHY layer defined in the IEEE 802.11 standard.

The transceiver 220 may include a transmitter 221 and a receiver 222. The antenna 230 may be configured as an antenna array to support multiple-input multiple-output (MIMO). The memory 240 may store commands executed by the baseband processor 210 and may be configured as at least one of a read only memory (ROM) and a random access memory (RAM). The input interface unit 250 may obtain information from the user of the communication node 200, and the output interface unit 260 may provide information to the user of the communication node 200. The baseband processor 210, the RF transceiver 220, the memory 240, the input interface unit 250, and the output interface unit 260 may be connected to each other through a bus.

Meanwhile, communication nodes (eg, access points, stations, etc.) belonging to a WLAN-based communication system may include a point coordination function (PCF), a hybrid coordination function (HCF), an HCF controlled channel access (HCCA), and a distributed coordination (DCF). A frame may be transmitted / received based on a function), an enhanced distributed channel access (EDCA), or the like.

Frames in a WLAN-based communication system may be classified into a management frame, a control frame, and a data frame. The management frame includes an association request frame, an association response frame, a reassociation request frame, a reassociation response frame, a probe request frame, a probe response frame, a beacon frame, and an association. It may include a disassociation frame, an authentication frame, a deauthentication frame, an action frame, and the like.

The control frame includes an acknowledgment (ACK) frame, a block ACK request (BAR) frame, a block ACK (BA) frame, a power saving (PS) -Poll frame, a request to send (RTS) frame, a clear to send (CTS) frame, and the like. It may include. Data frames may be classified into quality of service (QoS) data frames and non-QoS (non-QoS) data frames. QoS data frames may indicate data frames for which transmission in accordance with QoS is required, and non-QoS data frames may indicate data frames for which transmission in accordance with QoS is not required.

3 is a timing diagram showing a first embodiment of a method of operating a communication node based on EDCA.

Referring to FIG. 3, a communication node that wants to transmit a control frame (or a management frame) monitors channel conditions during a preset period (eg, short interframe space (SIFS), PCF IFS (PIFS)). Operation (eg, carrier sensing operation), and when the channel state is determined to be an idle state during a preset period (eg, SIFS, PIFS), the control frame ( Or a management frame). For example, the communication node may transmit an ACK frame, a BA frame, a CTS frame, and the like when the channel state is determined to be an idle state during SIFS. In addition, the communication node may transmit a beacon frame or the like when the channel state is determined to be an idle state during the PIFS. On the other hand, when it is determined that the channel state is busy during a preset period (eg, SIFS, PIFS), the communication node may not transmit a control frame (or a management frame). Here, the carrier sensing operation may indicate a clear channel assessment (CCA) operation.

A communication node that wants to transmit a non-QoS data frame may perform a channel state monitoring operation (eg, a carrier sensing operation) during DIFS (DCF IFS), and when the channel state is determined to be an idle state during DIFS. A random backoff procedure may be performed. For example, the communication node may select a backoff value (eg, a backoff counter) within a contention window according to a random backoff procedure, and the interval corresponding to the selected backoff value (hereinafter “back”). The channel state monitoring operation (eg, a carrier sensing operation) may be performed. The communication node may transmit a non-QoS data frame when the channel state is determined to be an idle state in the backoff period.

A communication node wishing to transmit a QoS data frame may perform a channel state monitoring operation (eg, carrier sensing operation) during an arbitration IFS (AIFS), and random back when the channel state is determined to be idle during AIFS. The off procedure can be performed. AIFS may be set according to an access category (AC) of a data unit (eg, a protocol data unit (PDU)) included in a QoS data frame. The AC of the data unit may be as shown in Table 1 below.

AC_BK may indicate background data, AC_BE may indicate data transmitted in a best effort manner, AC_VI may indicate video data, and AC_VO is voice ( voice) data can be indicated. For example, the length of the AIFS for the QoS data frame corresponding to each of AC_VO and AC_VI may be set equal to the length of the DIFS. The length of AIFS for the QoS data frame corresponding to AC_BE and AC_BK may be set longer than the length of DIFS. Here, the length of the AIFS for the QoS data frame corresponding to AC_BK may be set longer than the length of the AIFS for the QoS data frame corresponding to AC_BE.

In a random backoff procedure, the communication node may select a backoff value (eg, a backoff counter) within a contention window according to the AC of the QoS data frame. The competition window according to AC may be as shown in Table 2 below. CW _min may indicate the minimum value of the contention window, CW _max may indicate the maximum value of the contention window, and each of the minimum and maximum values of the contention window may be represented by the number of slots.

The communication node may perform a monitoring operation (eg, a carrier sensing operation) of the channel state in the backoff period, and transmit a QoS data frame when it is determined that the channel state is the idle state in the backoff period.

4 is a conceptual diagram illustrating a second embodiment of a WLAN-based communication system.

Referring to FIG. 4, the WLAN-based communication system includes an access point 400, a station supporting low power operation (hereinafter, referred to as a “low power station”) 411, 412, 413, and wake-up radio (WUR). Stations that do not support modes (hereinafter, referred to as "legacy stations") 421, 422, and 423 may be included. The low power stations 411, 412, 413 and the legacy stations 421, 422, 423 may belong to the coverage of the access point 400, and the access point 400 may be a low power station 411, 412, 413. And provide communication services to the legacy stations 421, 422, and 423. Low power station # 1 411 and legacy station # 2 422 may be smartphones, and include low power station # 2 412, low power station # 3 413, legacy station # 1 421 and legacy station # 3 ( 423 may be a sensor device.

The access point 400 may support communication protocols used by the low power stations 411, 412, 413 and the legacy stations 421, 422, 423, respectively. The low power stations 411, 412, 413 can use the communication protocol specified in the IEEE 802.11ba standard. In addition, the low power stations 411, 412, 413 can communicate not only in the IEEE 802.11ba standard, but also in other standards (e.g., IEEE 802.11a / b / g / n / p / ac / ax / ad / ay, etc.). Protocol can be used. Legacy stations 421, 422, and 423 may use communication protocols specified in standards other than IEEE 802.11ba (eg, IEEE 802.11a / b / g / n / p / ac / ax / ad / ay, etc.). have.

The legacy stations 421, 422, 423 may be configured identically or similarly to the communication node 200 shown in FIG. 2, and the low power stations 411, 412, 413 may be configured as follows.

5 is a block diagram illustrating a first embodiment of a low power station in a WLAN based communication system.

Referring to FIG. 5, the low power station 500 may include a baseband processor 510, a primary connectivity radio (PCR) 520, an antenna 530, a memory 540, an input interface unit 550, and an output interface unit ( 560, a wake-up receiver 570, and the like. For example, the low power station 500 may further include a WURx 570 compared to the communication node 200 of FIG. 2. The functions of each of the baseband processor 510, the PCR 520, the antenna 530, the memory 540, the input interface unit 550 and the output interface unit 560 included in the low power station 500 are illustrated in FIG. 2. The functions of the baseband processor 210, the transceiver 220, the antenna 230, the memory 240, the input interface unit 250, and the output interface unit 260 included in the communication node 200 may be the same or similar. Can be.

The PCR 520 of the low power station 500 may be referred to as a transceiver, and the WURx 570 of the low power station 500 may be referred to as a receiver. The PCR 520 of the low power station 500 may transmit and receive a non-high throughput (HT) physical protocol data unit (PPDU), an HT PPDU, a very high throughput (VHT) PPDU, or a high efficiency (DU) PPDU. Can be. Non-HT PPDUs, HT PPDUs, VHT PPDUs, or HE PPDUs may be referred to as legacy PPDUs (eg, legacy frames). The WURx 570 of the low power station 500 may receive a WUR PPDU (eg, a WUR frame).

That is, the low power station 500 may be a non-HT station, an HT station, a VHT station, or an HE station capable of transmitting and receiving a WUR PPDU. WURx 570 may be located within PCR 520 or may be configured independent of PCR 520. The WURx 570 and the PCR 520 may share the same antenna 530. Alternatively, the antenna for WURx 570 may be configured separately from the antenna for PCR 520. For example, low power station 500 may include a first antenna (not shown) for WURx 570 and a second antenna (not shown) for PCR 520. Communication between the WURx 570 and the PCR 520 may be performed using a primitive signal, a signal based on an application protocol interface (API), and the like.

The WURx 570 may operate in a narrow band (eg, 4 MHz, 8 MHz, 16 MHz, etc.), and the power consumption of the low power station 500 including the WURx 570 may be 1 mW or less. The WURx 570 may receive a signal (eg, a WUR wake-up frame) modulated in an on-off keying (OOK) scheme and perform demodulation on the received signal to obtain information included in the received signal. You can check it. The PCR 520 may transmit and receive a frame (eg, a control frame, a management frame, a data frame) defined in the IEEE 802.11 standard, and may operate in at least one of the 2.4 GHz frequency band and the 5 GHz frequency band. . In addition, the PCR 520 may support 20 MHz bandwidth, 40 MHz bandwidth, 80 MHz bandwidth, 160 MHz bandwidth, and the like.

Each of the PCR 520 and the WURx 570 may operate in a wake-up state or a sleep state. The wake up state may indicate a state in which power is supplied to the object (eg, PCR 520, WURx 570), and may be referred to as "on state", "activation state", " Enable state "," awake state ", and the like. The sleep state is a state in which the object (eg PCR 520, WURx 570) is not powered or that object (eg PCR 520, WURx 570) has minimal power. The supplied state may be indicated and may be referred to as an "off state", a "deactivation state", a "disable state", a "doze state", or the like.

The low power station 500 may support a normal mode that does not use WURx and a WUR mode that enables the use of WURx. In addition, the low power station 500 may support a WUR suspend mode. Even when parameters for the WUR operation are set, the low power station 500 may operate in a WUR grace mode that performs the low power operation of the existing PCR.

In normal mode, low power station 500 may perform the operation of PCR without the use of WURx, and may operate identically or similarly to communication node 200 of FIG.

In the WUR mode, when the PCR 520 of the low power station 500 operates in the wake up state, the WURx 570 of the low power station 500 may operate in the sleep state. For example, the PCR 520 operating in the wake-up state may perform a transmission / reception procedure of a frame (eg, a legacy frame or a legacy signal) with another communication node. On the other hand, when the PCR 520 of the low power station 500 operates in the sleep state, the WURx 570 of the low power station 500 may operate in the wake up state. In this case, the WURx 570 operating in the wakeup state may perform a monitoring operation (eg, a carrier sensing operation) on the channel to receive the WUR wakeup frame. Here, the WUR wakeup frame may request the PCR 520 of the low power station 500 to operate in the wakeup state.

When a WUR wakeup frame is received from another communication node at the low power station 500 operating in the WUR mode, the WURx 570 may transmit a wakeup indicator to the PCR 520 requesting to operate in the wakeup state. . When the wakeup indicator is received from the WURx 570, the operating state of the PCR 520 may transition from the sleep state to the wakeup state. When the wakeup indicator is transmitted to the PCR 520 or when the operation state of the PCR 520 transitions from the sleep state to the wakeup state, the operation state of the WURx 570 may transition from the wakeup state to the sleep state. have. Alternatively, when a sleep indicator is received from the PCR 520 requesting to operate in the sleep state, the operating state of the WURx 570 may transition from the wakeup state to the sleep state. Here, the time required for the PCR 520 to transition from the sleep state to the wake-up state may be referred to as a "state transition time". For example, the state transition time may indicate from the reception time of the WUR wakeup frame to the time point when the PCR 520 of the low power station operates in the wakeup state.

When the transmission / reception operation of the frame is completed, the operation state of the PCR 520 may transition from the wakeup state to the sleep state. In this case, the PCR 520 may transmit a wakeup indicator to the WURx 570 requesting to operate in the wakeup state. When the wakeup indicator is received from the PCR 520, the operating state of the WURx 570 may transition from the sleep state to the wakeup state. When the wakeup indicator is transmitted to the WURx 570 or when the operation state of the WURx 570 transitions from the sleep state to the wakeup state, the operation state of the PCR 520 may transition from the wakeup state to the sleep state. have.

In the WUR grace mode, the low power station 500 may operate the same or similar to the normal mode without performing the WUR operation. In this case, the low power station 500 may store the negotiated WUR parameters in the memory 540 without deleting the WUR parameters.

In addition, the baseband processor 510 (eg, the MAC processor 511 included in the baseband processor 510) may operate in a wake up state or a sleep state based on the operating state of the PCR 520. . For example, when the PCR 520 operates in the wake up state, the baseband processor 510 (eg, the MAC processor 511) may also operate in the wake up state, and the PCR 520 sleeps. When operating in the state, the baseband processor 510 (eg, the MAC processor 511) may also operate in the sleep state. For example, when a wake-up indicator requesting to operate in the wake-up state is received from the PCR 520 operating in the wake-up state, the baseband processor 510 (for example, the MAC processor 511) of the wake-up state is received. The operating state may transition from a sleep state to a wake up state. When a sleep indicator is received from the PCR 520 to operate in the sleep state and requests to operate in the sleep state, the operating state of the baseband processor 510 (eg, the MAC processor 511) is in the wakeup state. It may transition to a sleep state. Alternatively, the baseband processor 510 may always operate in the wakeup state regardless of the operation state of the PCR 520.

Meanwhile, the access point supporting the low power operation may be configured identically or similarly to the low power station 500 described above. For example, the access point includes a baseband processor 510, PCR 520, antenna 530, memory 540, input interface unit 550, output interface unit 560, WURx 570, and the like. can do. In addition, the access point may include a wake-up transmitter (WUTx) (not shown) instead of the WURx 570, or may include a wake-up radio (WUR) that performs the functions of the WURx 570 and the WUTx. have. The WUTx may perform an operation corresponding to the WURx 570. For example, WUTx may operate in narrow bands (eg, 4 MHz, 8 MHz, 16 MHz, etc.). The WUTx may transmit a modulated signal (eg, a WUR wakeup frame) in a OOK manner. In addition, the low power station 500 may further include a WUTx corresponding to the WURx 570. An access point that supports low power operation may be a non-HT access point, an HT access point, a VHT access point, or an HE access point.

6 is a block diagram illustrating a second embodiment of a low power station in a WLAN based communication system.

Referring to FIG. 6, the low power station 600 includes a baseband processor 610, transceiver # 1 620-1, transceiver # 2 620-2, antenna # 1 630-1, antenna # 2 ( 630-2), a memory 640, an input interface unit 650, an output interface unit 660, and the like. For example, the low power station 600 may further include transceiver # 2 620-2 and antenna # 2 630-2 as compared to the communication node 200 of FIG. 2. Baseband processor 610, transceiver # 1 620-1, antenna # 1 630-1, memory 640, input interface unit 650 and output interface unit 660 included in low power station 600. Each function may include a baseband processor 210, a transceiver 220, an antenna 230, a memory 240, an input interface unit 250, and an output interface unit 260 included in the communication node 200 of FIG. 2. ) May be the same as or similar to Each of transceiver # 1 620-1 and transceiver # 2 620-2 may be referred to as PCR # 1 and PCR # 2.

The functions of the transceiver # 2 620-2 and the antenna # 2 630-2 included in the low power station 600 are respectively the transceiver 220 and the antenna 230 included in the communication node 200 of FIG. 2. It may be the same or similar to the function of. Alternatively, the functionality of the transceiver # 1 620-1 included in the low power station 600 may be the same as or similar to that of the PCR 520 included in the communication node 500 of FIG. 5, and the low power station 600. The functionality of transceiver # 2 620-2 may be the same as or similar to that of the WURx 570 included in the communication node 500 of FIG. 5. Communication between the transceiver # 1 620-1 and the transceiver # 2 620-2 may be performed using a primitive signal, a signal according to an API, and the like. The low power station 600 may be a non-HT station, an HT station, a VHT station, or a HE station.

An access point that supports low power operation may be configured the same as or similar to the low power station 600 described above. For example, the access point may include a baseband processor 610, transceiver # 1 620-1, transceiver # 2 620-2, antenna # 1 630-1, antenna # 2 630-2, Memory 640, an input interface unit 650, an output interface unit 660, and the like. An access point that supports low power operation may be a non-HT access point, an HT access point, a VHT access point, or an HE access point.

Meanwhile, in a WLAN based communication system, a frequency band supported by PCR of a communication node (eg, an access point or a station) is IEEE 802.11 standard (eg, IEEE 802.11a / b / g / n / p / ac / ad / ax / ay) may be 10 MHz, 20 MHz, 40 MHz, 80 MHz, 160 MHz, or the like. In addition, one channel (channel, CH) in the frequency band supported by PCR may include a plurality of subchannels (SUB-CH). Here, the number and bandwidth of subchannels may be different according to the IEEE 802.11 standard (eg, IEEE 802.11a / b / g / n / p / ac / ad / ax / ay). For example, in a WLAN based communication system supporting the IEEE 802.11ax standard, a channel having a 20 MHz bandwidth may include up to nine subchannels according to the size of a resource unit (RU) allocated to a subchannel.

In a WLAN-based low power communication system, a channel may be set as follows.

7 is a conceptual diagram illustrating a first embodiment of a channel configuration in a WLAN-based communication system.

Referring to FIG. 7, a WURx of a communication node (eg, an access point or a low power station) may support a frequency band (eg, 4 MHz, 8 MHz, 16 MHz, etc.) of 20 MHz or less than 20 MHz. In addition, the channel used by WURx may include a plurality of subchannels, and the bandwidth of each of the plurality of subchannels may be smaller than the bandwidth supported by PCR. For example, the 40 MHz frequency band may consist of channel # 0 and channel # 1, and when the bandwidth of the subchannel is 4 MHz, each of channel # 0 and channel # 1 may include three or four subchannels. have. Here, a guard band (GB) may be located between the subchannels to protect each subchannel.

Next, methods of operating a communication node (eg, an access point, a station, etc.) supporting low power operation in a WLAN based communication system will be described. Even when the method (for example, transmission or reception of a frame) is described among the communication nodes, the corresponding second communication node corresponds to the method (for example, the method performed in the first communication node). For example, reception or transmission of a frame) may be performed. That is, when the operation of the station is described, the access point corresponding thereto may perform an operation corresponding to the operation of the station. Conversely, when the operation of the access point is described, the corresponding station may perform an operation corresponding to the operation of the access point.

8 is a timing diagram illustrating a first embodiment of a method of operating a communication node in a WLAN-based communication system.

Referring to FIG. 8, a WLAN-based communication system may include an access point (AP), a low power station (LP STA), and the like. The low power station may belong to the access point's coverage and may be connected to the access point. The access point and low power station may be configured identically or similarly to the low power station 500 of FIG. 5. In addition, the access point and low power station may further include a WUTx as compared to the low power station 500 of FIG. 5. Alternatively, the access point and low power station may be configured identically or similarly to the low power station 600 of FIG. 6. The access point and the low power station may operate based on the EDCA scheme shown in FIG.

When the low power station is operating in the WUR mode, the access point may send a WUR wake up frame 801 to wake up the low power station. For example, the access point may generate the WUR wakeup frame 801, and transmit the WUR wakeup frame 801 to the low power station when the state of the channel is determined to be the idle state in the carrier sensing period. In the following embodiments, the carrier sensing interval may be a SIFS, PIFS, DIFS, AIFS, "DIFS + backoff interval", "AIFS [AC_VO] + backoff [AC_VO] interval", "AIFS [AC_VI] + shown in FIG. Backoff [AC_VI] section "," AIFS [AC_BE] + backoff [AC_BE] section "or" AIFS [AC_BK] + backoff [AC_BK] section ".

The WUR wakeup frame 801 may be set as follows.

9 is a block diagram illustrating a first embodiment of a WUR wakeup frame in a WLAN-based communication system.

Referring to FIG. 9, the WUR wakeup frame 900 may include a legacy preamble and a WUR payload 950. The legacy preamble may include a legacy short training field (L-STF) 910, a legacy long training field (L-LTF) 920, and a legacy signal (L-SIG) field 930. The size of the frequency band to which the legacy preamble is mapped may be 20 MHz. In addition, the legacy preamble may further include a binary phase shift keying (BPSK) -mark 940. The BPSK-mark 940 may be composed of one symbol (eg, an orthogonal frequency division multiplexing (OFDM) symbol) modulated in a BPSK scheme.

The BPSK-mark 940 indicates that a legacy station (for example, a station supporting IEEE 802.11n) incorrectly determines the WUR wakeup frame 900 as another IEEE 802.11 frame and thus, after the legacy preamble according to occurrence of a frame error. It may be used to prevent the monitoring of the channel state for the signal (eg, carrier sensing operation, energy detection (ED) operation). When the legacy station performs an energy detection (ED) operation in the 20 MHz bandwidth due to an error in frame recognition, the WUR payload 950 because the transmission bandwidth of the WUR payload 950 is narrow and the reception power detected by the ED operation is low. Frame may be transmitted in the transmission interval of the Rx. To avoid this problem, the BPSK-mark 940 can be used.

The WUR payload 950 may be demodulated based on the OOK scheme. The size of the frequency band to which the WUR payload 950 is mapped may be less than 20 MHz. The WUR payload 950 may further include a WUR sync field 951 and a WUR data field 952. The WUR sync field 951 may include a pseudo random (PN) sequence used for synchronization between the access point and the low power station (eg, WURx included in the low power station). In addition, the PN sequence may indicate data rate and bandwidth.

The WUR data field 952 includes a frame control field 952-1, an address field 952-2, a TD control field 952-3, a frame body 952-4, and a frame check sequence. Field 952-5). The address field 952-2 may indicate an identifier (eg, an association identifier (AID)) of a low power station or a group identifier of low power stations that will receive the WUR wakeup frame 900. Each of the TD control field 952-3 and frame body 952-4 may include information elements required for low power operation (eg, operation according to the WUR mode).

Referring back to FIG. 8, the WUR wakeup frame 801 may be the same as or similar to the WUR wakeup frame 900 of FIG. 9. The access point may send a WUR wakeup frame 801. The WURx of the low power station may receive a WUR wakeup frame 801 and the wakeup target indicated by the WUR wakeup frame 801 (ie, the communication node indicated by the address field) is a low power station. PCR can be woken up. That is, when the WUR wakeup frame 801 is received, the operating state of the PCR of the low power station may transition from the sleep state to the wakeup state.

The PCR of the low power station operating in the wake up state may send a WUR-poll frame 802 to the access point. The WUR-poll frame 802 may be transmitted when the channel state is idle in the carrier sensing period. The WUR-pole frame 802 may indicate that the operating state of the PCR of the low power station has transitioned from the sleep state to the wake up state. Here, the WUR-pol frame 802 may be a power saving (PS) -pol frame, an unscheduled-automatic power saver delivery (U-APSD) frame, or any frame (eg, a null frame). .

When the WUR-pole frame 802 is received from the low power station, the access point may determine that the operating state of the PCR of the low power station has transitioned from the sleep state to the wake up state. The access point may send an ACK frame (not shown) to the low power terminal in response to the WUR-pole frame 802. The ACK frame may be sent after SIFS from the end of the WUR-Poll frame 802. In this case, transmission of an ACK frame, which is a response to the WUR-pol frame 802, may be omitted.

If it is determined that the PCR of the low power station is operating in a wake up state, the access point may transmit a data frame 803 to the low power station. The data frame 803 may be transmitted when the channel state is idle in the carrier sensing period. The low power station may receive the data frame 803 from the access point and may send an ACK frame 804 to the access point in response to the data frame 803 if the data frame 803 is successfully received. . The ACK frame 804 may be sent after SIFS from the end of the data frame 803. The access point may determine that the data frame 803 was successfully received at the low power station when the ACK frame 804 is received.

On the other hand, in order to further reduce standby power in the low power station, the WURx included in the low power station may periodically transition from the wake up state to the sleep state. The period in which the WURx contained in the low power station transitions from the sleep state to the wake-up state, the time that the WURx contained in the low power station remains in the wake-up state, etc. is the WUR operation between the access point and the low power station (eg, WUR mode). It may be established in a negotiation procedure for the Accordingly, when data to be transmitted to the low power station exists in the access point, the access point may transmit the WUR wakeup frame 801 to the low power station in consideration of the operating state of the WURx included in the low power station.

FIG. 10 is a block diagram illustrating a second embodiment of a WUR wakeup frame in a WLAN-based communication system.

Referring to FIG. 10, the WUR wakeup frame may be transmitted in a frequency division multiple access (FDMA) scheme. Each of the L-STF, L-LTF, L-SIG field, BPSK-mark, and WUR payload shown in FIG. 10 is L-STF 910, L-LTF 920, and L-SIG shown in FIG. It may be the same as or similar to the field 930, the BPSK-mark 940, and the WUR payload 950. One WUR frame (eg, WUR wakeup frame) may be transmitted over a 20 MHz band. Therefore, the number of WUR frames that can be transmitted in the same time interval may be determined according to the size of the frequency band supported by the access point.

For example, if the size of the frequency band supported by the access point is 40 MHz, the access point may transmit two WUR wakeup frames to the low power stations. Alternatively, if the size of the frequency band supported by the access point is 80 MHz, the access point may transmit four WUR wakeup frames to the low power stations. In this case, the access point can transmit WUR wakeup frames to low power station # 1 using channel # 1, transmit WUR wakeup frames to low power station # 2 using channel # 2, and transmit channel # 3. Can be used to transmit WUR wakeup frames to low power station # 3, and channel # 4 can be used to transmit WUR wakeup frames to low power station # 4. Channel # 1 may be a primary channel, and channels # 2-4 may be secondary channels. One secondary channel may consist of one or more channels. For example, secondary channel # 1 may be configured as channel # 2, and secondary channel # 2 may be configured as channels # 3-4. A padding bit may be added to each of the WUR wakeup frames to equally match the length of the WUR wakeup frames transmitted over the plurality of frequency bands.

The channel through which the WUR wakeup frame is transmitted may be established in a negotiation procedure for WUR operation between the access point and the low power station. For example, in the negotiation procedure for WUR operation between the access point and the low power station # 1, the WUR wakeup frame for the low power station # 1 may be set to be transmitted on the primary channel (eg, channel # 1). Can be. Therefore, the WURx included in the low power station # 1 can monitor the primary channel to receive the WUR wakeup frame. In this same manner, secondary channel # 1 (e.g., channel # 2) used for transmission of the WUR wakeup frame for low power station # 2 may be established, and the WUR wakeup frame for low power station # 3 Secondary channel # 2 (e.g., channels # 3-4) may be set used for transmission of the secondary channel # 2 (e.g., channel # 3-4) used for transmission of the WUR wakeup frame for the low power station # 4. For example, channels # 3-4 may be set.

On the other hand, if "one or more of channels # 1-4 are not idle" or "if there is no data to be transmitted to low power stations using one or more of channels # 1-4", the access point WUR wakeup frames may be transmitted using the remaining channels except for one or more channels among channels # 1-4. In this case, the WUR wakeup frame may not be transmitted continuously on the frequency axis.

11 is a timing diagram illustrating a second embodiment of a method of operating a communication node in a WLAN-based communication system.

Referring to FIG. 11, a WLAN-based communication system includes an access point (AP), a low power station # 1 (LP STA # 1), a low power station # 2 (LP STA # 2), and a low power station # 3 (LP STA # 3). ), Low power station # 4 (LP STA # 4), and the like. Low power station # 1-4 may belong to the access point's coverage and may be connected to the access point. Access point and low power station # 1-4 may be configured the same as or similar to the low power station 500 of FIG. Also, the access point and low power station # 1-4 may further include a WUTx as compared to the low power station 500 of FIG. Alternatively, the access point and low power station # 1-4 may be configured the same as or similar to the low power station 600 of FIG. The access point and low power station # 1-4 may operate based on the EDCA scheme shown in FIG.

In addition, in a WLAN-based communication system, the primary channel may be set to channel # 1 shown in FIG. 10, the secondary channel # 1 may be set to channel # 2 shown in FIG. 10, and the secondary channel # 2 may be set to channel # 3-4 shown in FIG. 10. In the negotiation procedure for the WUR operation between the access point and the low power station # 1, an operating channel of the low power station # 1 may be set as a primary channel. In the negotiation procedure for the WUR operation between the access point and the low power station # 2, the operating channel of the low power station # 2 may be set to the secondary channel # 1. In the negotiation procedure for the WUR operation between the access point and the low power station # 3, the operating channel of the low power station # 3 may be set to the secondary channel # 2. In the negotiation procedure for the WUR operation between the access point and the low power station # 4, the operating channel of the low power station # 4 may be set to the secondary channel # 2.

The access point may send a WUR Beacon frame 1101 on the primary channel. The WUR Beacon Frame may include a MAC Header, Frame Body, and FCS Field. The frame body of the WUR Beacon frame may include one or more elements of a WUR capability element, a WUR operation element, and a WUR discovery element. Low power station # 1-4 may monitor the primary channel to receive the WUR beacon frame. The low power station # 1-4 may receive a WUR beacon frame on the primary channel and check the information included in the WUR beacon frame. Since the operating channel of the low power station # 2-4 is not the primary channel, the low power station # 2-4 may change the channel from the secondary channel to the primary channel before the reception time of the WUR beacon frame. The negotiation procedure for the WUR operation between the access point and the low power station # 1-4 may be performed at a time when the WUR beacon frame is not transmitted. In addition, the access point may transmit the WUR wakeup frames 1102-1 to 1102-4 to the low power station # 1-4 at a time when the WUR beacon frame is not transmitted.

If data to be transmitted to the low power station # 1-4 is present in the access point, the access point may transmit the WUR wakeup frames 1102-1 to 1102-4 to the low power station # 1-4. For example, the access point may transmit the WUR wakeup frame 1102-1 to the low power station # 1 using the primary channel when it is determined that the primary channel is in the idle state according to the EDCA scheme. When the WUR wake-up frame 1102-1 is transmittable through the primary channel, the access point may be "IFS in accordance with EDCA + priority interframe space (PIFS)", "IFS in accordance with EDCA", or "PIFS". If the secondary channel # 1-2 is determined to be in the idle state, the WUR wakeup frames 1102-2 to 1102-4 can be transmitted to the low power station # 2-4 using the secondary channel # 1-2. The WUR wakeup frames 1102-2-1102-4 can be transmitted after PIFS than the WUR wakeup frames 1102-1. Alternatively, the WUR wakeup frames 1102-1 to 1102-4 may be transmitted simultaneously.

Low power station # 1 (eg, WURx included in low power station # 1) may receive the WUR wakeup frame 1102-1 by monitoring the primary channel. In this case, the operating state of the PCR included in the low power station # 1 may transition from the sleep state to the wake up state, and the low power station # 1 may receive a data frame from the access point. Here, the data frame may be received through the primary channel. Alternatively, the data frame may be received over another channel instead of the primary channel (ie, the channel through which the WUR wakeup frame is received).

Low power station # 2 (eg, WURx included in low power station # 2) may receive WUR wakeup frame 1102-2 by monitoring secondary channel # 1. In this case, the operating state of the PCR included in the low power station # 2 may transition from the sleep state to the wake up state, and the low power station # 2 may receive a data frame from the access point. Here, the data frame may be received through the secondary channel # 1. Alternatively, the data frame may be received over another channel instead of secondary channel # 1 (ie, the channel through which the WUR wakeup frame is received).

Low power station # 3 (eg, WURx included in low power station # 3) may receive WUR wakeup frame 1102-3 by monitoring secondary channel # 2. Here, the WUR wakeup frame 1102-3 may be received through channel # 3 (ie, channel # 3 illustrated in FIG. 10) belonging to the secondary channel # 2. In this case, the operating state of the PCR included in the low power station # 3 may transition from the sleep state to the wake up state, and the low power station # 3 may receive a data frame from the access point. Here, the data frame may be received through channel # 3 belonging to secondary channel # 2. Alternatively, the data frame may be received through another channel instead of channel # 3 (ie, a channel for receiving a WUR wakeup frame) belonging to the secondary channel # 2.

Low power station # 4 (eg, WURx included in low power station # 4) may receive WUR wakeup frame 1102-4 by monitoring secondary channel # 2. Here, the WUR wakeup frame 1102-4 may be received through channel # 4 (ie, channel # 4 illustrated in FIG. 10) belonging to the secondary channel # 2. In this case, the operating state of the PCR included in the low power station # 4 may transition from the sleep state to the wake up state, and the low power station # 4 may receive a data frame from the access point. Here, the data frame may be received through channel # 4 belonging to the secondary channel # 2. Alternatively, the data frame may be received through another channel instead of channel # 4 (ie, a channel for receiving a WUR wakeup frame) belonging to the secondary channel # 2.

Meanwhile, the WUR wakeup frame may be transmitted using some frequency bands among all frequency bands. For example, if "No data to be sent to low power station # 3-4 is present on the access point" or "Secondary channel # 2 is not idle", the access point will wake up the WUR via secondary channel # 2. The frame may not be transmitted. In this case, the access point may transmit the WUR wakeup frame 1103-1 to the low power station # 1 using the primary channel when it is determined that the primary channel is in the idle state according to the EDCA scheme. If the WUR wakeup frame 1103-1 is transmitable over the primary channel, the access point may be assigned to secondary channel # 1 during "IFS + PIFS according to EDCA scheme", "IFS according to EDCA scheme", or "PIFS". If it is determined that the idle state, the secondary channel # 1 may be used to transmit the WUR wakeup frame 1103-2 to the low power station # 2. The WUR wakeup frame 1103-2 may be transmitted after PIFS than the WUR wakeup frame 1103-1. Alternatively, the WUR wakeup frames 1103-1 and 1103-2 may be transmitted simultaneously.

Low power station # 1 (eg, WURx included in low power station # 1) may receive the WUR wakeup frame 1103-1 by monitoring the primary channel. In this case, the operating state of the PCR included in the low power station # 1 may transition from the sleep state to the wake up state, and the low power station # 1 may receive a data frame from the access point. Here, the data frame may be received through the primary channel. Alternatively, the data frame may be received over another channel instead of the primary channel (ie, the channel through which the WUR wakeup frame is received).

Low power station # 2 (eg, WURx included in low power station # 2) may receive WUR wakeup frame 1103-2 by monitoring secondary channel # 1. In this case, the operating state of the PCR included in the low power station # 2 may transition from the sleep state to the wake up state, and the low power station # 2 may receive a data frame from the access point. Here, the data frame may be received through the secondary channel # 1. Alternatively, the data frame may be received over another channel instead of secondary channel # 1 (ie, the channel through which the WUR wakeup frame is received).

Low power station # 3-4 may not receive a WUR wakeup frame from the access point. Therefore, the PCR included in the low power station # 3-4 can maintain the sleep state.

12 is a timing diagram illustrating a third embodiment of a method of operating a communication node in a WLAN-based communication system.

Referring to FIG. 12, a WLAN-based communication system includes an access point (AP), a low power station # 1 (LP STA # 1), a low power station # 2 (LP STA # 2), and a low power station # 3 (LP STA # 3). ), Low power station # 4 (LP STA # 4), and the like. Low power station # 1-4 may belong to the access point's coverage and may be connected to the access point. Access point and low power station # 1-4 may be configured the same as or similar to the low power station 500 of FIG. Also, the access point and low power station # 1-4 may further include a WUTx as compared to the low power station 500 of FIG. Alternatively, the access point and low power station # 1-4 may be configured the same as or similar to the low power station 600 of FIG. The access point and low power station # 1-4 may operate based on the EDCA scheme shown in FIG.

In addition, in a WLAN-based communication system, the primary channel may be set to channel # 1 shown in FIG. 10, the secondary channel # 1 may be set to channel # 2 shown in FIG. 10, and the secondary channel # 2 may be set to channel # 3-4 shown in FIG. 10. In the negotiation procedure for the WUR operation between the access point and the low power station # 1, the operating channel of the low power station # 1 may be set as a primary channel. In the negotiation procedure for the WUR operation between the access point and the low power station # 2, the operating channel of the low power station # 2 may be set to the secondary channel # 1. In the negotiation procedure for the WUR operation between the access point and the low power station # 3, the operating channel of the low power station # 3 may be set to the secondary channel # 2. In the negotiation procedure for the WUR operation between the access point and the low power station # 4, the operating channel of the low power station # 4 may be set to the secondary channel # 2.

If a particular channel is busy at the time of transmission of the WUR wakeup frame, the access point may not transmit the WUR wakeup frame. For example, if data to be transmitted to the low power station # 2 exists in the access point, and the secondary channel # 1 is busy at the time of transmission of the WUR wakeup frame, the access point removes the WUR wakeup frame from the secondary channel # 1. It may not be able to transmit to low power station # 2. In this case, it is necessary to change the operation channel of the low power station # 2 to another channel.

In order to change the operating channel of the low power station # 2, a negotiation procedure for the WUR operation between the access point and the low power station # 2 should be performed. However, although low power station # 2 needs to be woken up for the negotiation procedure for WUR operation, it may be difficult to transmit the WUR wakeup frame to low power station # 2 when the secondary channel # 1 is busy. That is, changing the operating channel of low power station # 2 can be difficult.

In order to solve this problem, an active cycle period and an alive timer may be set in a WLAN-based communication system. The alive cycle duration and the alive timer may be set in the negotiation procedure for the WUR operation between the access point and the low power station. The alive cycle interval may be set to one or more WUR duty cycle intervals. When the alive cycle interval and the alive timer are set, the communication node may operate as follows.

FIG. 13 is a timing diagram illustrating a fourth embodiment of a method of operating a communication node in a WLAN-based communication system.

Referring to FIG. 13, a WLAN-based communication system includes an access point (AP), a low power station # 1 (LP STA # 1), a low power station # 2 (LP STA # 2), and a low power station # 3 (LP STA # 3). ), Low power station # 4 (LP STA # 4), and the like. Low power station # 1-4 may belong to the access point's coverage and may be connected to the access point. Access point and low power station # 1-4 may be configured the same as or similar to the low power station 500 of FIG. Also, the access point and low power station # 1-4 may further include a WUTx as compared to the low power station 500 of FIG. Alternatively, the access point and low power station # 1-4 may be configured the same as or similar to the low power station 600 of FIG. The access point and low power station # 1-4 may operate based on the EDCA scheme shown in FIG.

In addition, in a WLAN-based communication system, the primary channel may be set to channel # 1 shown in FIG. 10, the secondary channel # 1 may be set to channel # 2 shown in FIG. 10, and the secondary channel # 2 may be set to channel # 3-4 shown in FIG. 10. In the negotiation procedure for the WUR operation between the access point and the low power station # 1, the operating channel of the low power station # 1 may be set as a primary channel. In the negotiation procedure for the WUR operation between the access point and the low power station # 2, the operating channel of the low power station # 2 may be set to the secondary channel # 1. In the negotiation procedure for the WUR operation between the access point and the low power station # 3, the operating channel of the low power station # 3 may be set to the secondary channel # 2. In the negotiation procedure for the WUR operation between the access point and the low power station # 4, the operating channel of the low power station # 4 may be set to the secondary channel # 2.

Even when there is no data to be transmitted to the low power station, the access point may transmit a null WUR wakeup frame to the corresponding low power station in the lifetime cycle. For example, if there is no data to be transmitted to low power station # 3 in alive cycle period # 1, the access point may transmit a null WUR wakeup frame to low power station # 3. In addition, when there is no data to be transmitted to the low power station # 2 in the alive cycle period # 2, the access point may transmit a null WUR wakeup frame to the low power station # 2.

 The null WUR wakeup frame may consist of a simple WUR frame and may include an identifier of the low power station being received. Alternatively, a null WUR wakeup frame may include a specific address or a specific group address instead of the identifier of the low power station.

The low power station receiving the null WUR wakeup frame may determine that the channel is valid. That is, the low power station may determine that the channel is effectively managed by the access point. Since the null WUR wakeup frame is not a WUR wakeup frame to wake up the low power station, the PCR included in the low power station receiving the null WUR wakeup frame may remain in a sleep state.

The alive timer may indicate the time that the channel is valid and may be a time corresponding to one or more alive cycle intervals. If a WUR wakeup frame or null WUR wakeup frame is received from the access point before expiration of the alive timer, the low power station may determine that the channel is valid and may initialize the alive timer. On the other hand, if a WUR wakeup frame or a null WUR wakeup frame is not received from the access point before expiration of the alive timer, the low power station may determine that the channel is invalid. In this case, the PCR included in the low power station may transition from the sleep state to the wake up state, and the low power station may perform a procedure of changing the access point and the operating channel. For example, the low power station may send a frame to the access point requesting a change of operating channel. The procedure of changing the operation channel may be performed the same as or similar to the negotiation procedure for the WUR operation. When the change of the operating channel is completed, the WURx included in the low power station may monitor the changed operating channel to receive the WUR wakeup frame.

On the other hand, the procedure of changing the operation channel may be triggered by the access point.

FIG. 14 is a timing diagram illustrating a fifth embodiment of a method of operating a communication node in a WLAN-based communication system.

Referring to FIG. 14, a WLAN-based communication system includes an access point (AP), a low power station # 1 (LP STA # 1), a low power station # 2 (LP STA # 2), and a low power station # 3 (LP STA # 3). ), Low power station # 4 (LP STA # 4), and the like. Low power station # 1-4 may belong to the access point's coverage and may be connected to the access point. Access point and low power station # 1-4 may be configured the same as or similar to the low power station 500 of FIG. Also, the access point and low power station # 1-4 may further include a WUTx as compared to the low power station 500 of FIG. Alternatively, the access point and low power station # 1-4 may be configured the same as or similar to the low power station 600 of FIG. The access point and low power station # 1-4 may operate based on the EDCA scheme shown in FIG.

In addition, in a WLAN-based communication system, the primary channel may be set to channel # 1 shown in FIG. 10, the secondary channel # 1 may be set to channel # 2 shown in FIG. 10, and the secondary channel # 2 may be set to channel # 3-4 shown in FIG. 10. In the negotiation procedure for the WUR operation between the access point and the low power station # 1, the operating channel of the low power station # 1 may be set as a primary channel. In the negotiation procedure for the WUR operation between the access point and the low power station # 2, the operating channel of the low power station # 2 may be set to the secondary channel # 1. In the negotiation procedure for the WUR operation between the access point and the low power station # 3, the operating channel of the low power station # 3 may be set to the secondary channel # 2. In the negotiation procedure for the WUR operation between the access point and the low power station # 4, the operating channel of the low power station # 4 may be set to the secondary channel # 2.

If the data to be transmitted to the low power station # 2 is present in the access point, and the secondary channel # 1 is busy at the time of transmission of the WUR wakeup frame for the low power station # 2, the access point is WUR wakeup on the secondary channel # 1. The frame may not be transmitted. If the WUR wake-up frame is not transmitted to the low power station # 2 during a preset time (eg, an alive cycle period, an alive timer), the access point may determine that the operation channel of the low power station # 2 needs to be changed. .

In this case, the access point may transmit the WUR wakeup frame 1405 in a primary channel after the transmission of the WUR beacon frame 1404 in a broadcast manner. The WUR Beacon Frame 1404 may include an indicator that the WUR Wakeup Frame 1405 is transmitted in succession with the WUR Beacon Frame 1404.

The receiving target of the WUR wakeup frame 1405 may be low power station # 2, all low power stations, or low power stations belonging to a particular group. For example, the destination address of the WUR wakeup frame 1405 may be set to an identifier of low power station # 2, a broadcasting identifier, a group identifier, or identifiers of a plurality of low power stations. Identifiers of the plurality of low power stations may be included in the frame body of the WUR wakeup frame 1405.

Low power station # 1-4 may receive the WUR Beacon frame 1404 from the access point, and WUR wakeup frame 1405 in succession with the WUR Beacon frame 1404 by identifying an indicator included in the WUR Beacon frame 1404. ) May be determined to be transmitted. Accordingly, the WURx of the low power station # 1-4 may maintain a wake up state even after receiving the WUR beacon frame 1404, and may receive the WUR wakeup frame 1405 from the access point.

When the destination address of the WUR wakeup frame 1405 is low power station # 2, the PCR included in the low power station # 2 may transition from the sleep state to the wake up state, and perform a procedure of changing the access point and the operating channel. Can be. For example, in a change procedure of the operating channel, the access point may transmit a change request frame to the low power station # 2 that includes information indicating the changed operating channel. The low power station # 2 may receive a change request frame from the access point, identify an operating channel indicated by the change request frame, and send an ACK frame for the change request frame to the access point. Accordingly, the WURx included in the low power station # 2 may perform a monitoring operation on an operation channel indicated by the change request frame.

Alternatively, when the destination address of the WUR wakeup frame 1405 is set to the broadcasting identifier, the PCR included in the low power station # 1-4 may transition from the sleep state to the wakeup state, and change the access point and operating channel. The procedure can be performed. That is, the access point can reset the operating channel of all low power stations # 1-4. Therefore, in the operation channel change procedure, the access point may transmit a change request frame including information indicating the changed operation channel to each of the low power stations # 1-4. The low power station # 1-4 may receive a change request frame from the access point, identify an operating channel indicated by the change request frame, and send an ACK frame for the change request frame to the access point. Accordingly, the WURx included in the low power station # 1-4 may perform a monitoring operation on an operation channel indicated by the change request frame.

Meanwhile, the low power station includes WURx and PCR, and the PCR included in the low power station may operate in a sleep state. If the PCR operates in the sleep state, the function of the PCR may be stopped. The PCR may transition from the sleep state to the wake up state according to the signal received at the WURx (or processor). In addition, the WURx included in the low power station may operate in a wake up state or a sleep state. For example, the WURx may operate in a wake-up state at on duration within the WUR duty cycle period, and may operate in a sleep state at a time interval except for the duration in the WUR duty cycle period. For low power communication, the low power station may use a power save multi poll (PSMP) scheme. In this case, the communication nodes (eg, access point and low power station) may operate as follows.

15 is a timing diagram illustrating a sixth embodiment of a method of operating a communication node in a WLAN-based communication system.

Referring to FIG. 15, a WLAN-based communication system may include an access point (AP), a low power station (LP STA), and the like. The low power station may belong to the access point's coverage and may be connected to the access point. The access point and low power station may be configured identically or similarly to the low power station 500 of FIG. 5. In addition, the access point and low power station may further include a WUTx as compared to the low power station 500 of FIG. 5. Alternatively, the access point and low power station may be configured identically or similarly to the low power station 600 of FIG. 6. The access point and the low power station may operate based on the EDCA scheme shown in FIG.

The access point may send a WUR wakeup frame 1501. The WURx included in the low power station may operate in a wake up state prior to the reception time of the WUR wakeup frame 1501 and may receive the WUR wakeup frame 1501 from the access point. When the WUR wakeup frame 1501 is received, the WURx (or processor) included in the low power station may wake up the PCR. The PCR may transition from the sleep state to the wake up state after the wake up delay time (eg, state transition time).

The access point knows the wakeup delay time of the PCR included in the low power station, and may transmit the PSMP frame 1502 to the low power station after the wakeup delay time. The PSMP frame 1502 may be interpreted by the plurality of low power stations and may include time information allocated for the plurality of low power stations within the PSMP service interval. The plurality of low power stations may transmit and receive frames at the time indicated by the PSMP frame 1502. In addition, the plurality of low power stations may perform a power saving operation in the PSMP service interval.

Meanwhile, a target wake time (TWT) may be set between the access point and the low power station. In this case, the PCR included in the low power station may transition from the sleep state to the wake-up state in the TWT, and may maintain the wake-up state for a predetermined time from the TWT (for example, a TWT SP (service period)). The set time may be set in advance in a negotiation procedure between the access point and the low power station When the TWT is set in the WLAN based communication system, the communication node (eg, the access point and the low power station) may operate as follows. have.

FIG. 16 is a timing diagram illustrating a seventh embodiment of a method of operating a communication node in a WLAN-based communication system.

Referring to FIG. 16, a WLAN-based communication system may include an access point (AP), a low power station (LP STA), and the like. The low power station may belong to the access point's coverage and may be connected to the access point. The access point and low power station may be configured identically or similarly to the low power station 500 of FIG. 5. In addition, the access point and low power station may further include a WUTx as compared to the low power station 500 of FIG. 5. Alternatively, the access point and low power station may be configured identically or similarly to the low power station 600 of FIG. 6. The access point and the low power station may operate based on the EDCA scheme shown in FIG.

The low power station may generate a first frame including WUR capability information (S1610). The first frame may be configured as follows.

17 is a block diagram illustrating a first frame in a WLAN-based communication system.

Referring to FIG. 17, a first frame 1700 may include an element ID field 1710, a length field 1720, an element ID extension field 1730, a supported band field 1740, and the like. And a WUR capability information field 1750. The WUR capability information field 1750 may include a first indicator indicating whether the TWT function is supported. The size of the first indicator may be 1 bit. For example, the first indicator set to "0" may indicate that the low power station does not support the TWT function. The first indicator set to "1" may indicate that the low power station supports the TWT function.

Referring back to FIG. 16, the low power station may transmit a first frame to the access point (S1620). The first indicator included in the WUR capability information field of the first frame may indicate that the low power station supports the TWT function. The access point may receive a first frame from the low power station, and may check information (eg, WUR capability information) included in the first frame (S1630). For example, the access point may confirm that the low power station supports the TWT function based on the information included in the first frame.

The access point may transmit a second frame indicating that the information included in the first frame has been confirmed to the low power station (S1640). The second frame may be an ACK frame for the first frame. Also, the second frame may include information indicating TWT and information indicating TWT SP). Alternatively, if the low power station is found to support the TWT function, the access point may perform a separate procedure with the low power station to negotiate the TWT. Or "when information indicating TWT and information indicating TWT SP is included in WUR mode acknowledgment frame" or "if a separate procedure for negotiating TWT has been performed", information indicating TWT and TWT SP The indicating information may not be included in the second frame.

The low power station may receive a second frame from the access point. When the second frame is received, the low power station may determine that the information included in the first frame has been confirmed by the access point. The low power station may also identify the TWT and TWT SP indicated by the second frame. Therefore, the PCR included in the low power station may transition from the sleep state to the wake up state in the TWT, and may maintain the wake up state during the TWT SP.

Thereafter, a negotiation procedure for WUR operation between the access point and the low power station may be performed. In the negotiation procedure for the WUR operation, the low power station may generate a WUR mode request frame including a second indicator requesting to perform the TWT operation (S1650). The WUR mode request frame may be configured as follows.

18 is a block diagram illustrating a first embodiment of a WUR mode request frame in a WLAN-based communication system.

Referring to FIG. 18, the WUR mode request frame 1800 includes an element ID field 1810, a length field 1820, an element ID extension field 1830, a minimum wakeup duration field 1840, and a duty cycle interval unit (unit). ) Field 1850, WUR channel field 1860, WUR beacon period field 1870, target WUR beacon transmission time (TWBTT) offset field 1880, and WUR parameter field 1890. . The WUR parameter field 1890 may include a second indicator indicating whether to perform a TWT operation. The size of the second indicator may be 1 bit. For example, the second indicator set to "0" may instruct to stop performing the TWT operation. The second indicator set to "1" may request to perform the TWT operation.

Referring back to FIG. 16, the low power station may transmit a WUR mode request frame to the access point (S1660). The second indicator included in the WUR parameter field of the WUR mode request frame may request to perform a TWT operation. The access point may receive a WUR mode request frame from the low power station, and may check information (eg, a WUR parameter) included in the WUR mode request frame (S1670). For example, the access point may confirm that the TWT operation is requested to be performed based on the information included in the WUR mode request frame.

If the operation requested by the WUR mode request frame (eg, the TWT operation) is approved, the access point may transmit the WUR mode grant frame to the low power station (S1680). The WUR mode acknowledgment frame may include information indicating TWT and information indicating TWT SP. Alternatively, when the information indicating the TWT and the information indicating the TWT SP are included in the second frame, the information indicating the TWT and the information indicating the TWT SP may not be included in the WUR mode grant frame.

The low power station may receive a WUR mode grant frame from the access point. If a WUR mode grant frame is received, the low power station may determine that the operation requested by the WUR mode request frame (eg, a TWT operation) has been approved by the access point. The low power station may also identify the TWT and TWT SPs indicated by the WUR mode acknowledgment frame. Therefore, the PCR included in the low power station may transition from the sleep state to the wake up state in the TWT, and may maintain the wake up state during the TWT SP.

Meanwhile, steps S1610 to S1640 may be performed to request execution of the TWT operation. In this case, step S1650 to step S1680 may be omitted. Therefore, when the second frame is received from the access point, the low power station may determine that the TWT operation is performed. Alternatively, steps S1650 to S1680 may be performed to request the execution of the TWT operation. In this case, step S1610 to step S1640 may be omitted. That is, steps S1650 to S1680 may be performed without a procedure for notifying information indicating whether the TWT function is supported. Accordingly, the low power station supporting the TWT function may transmit a WUR mode request frame to the access point requesting to perform the TWT operation. On the other hand, a low power station that does not support the TWT function may not transmit a WUR mode request frame to the access point requesting to perform the TWT operation.

If the execution of the TWT operation is approved, a low power communication operation according to the TWT function may be performed between the access point and the low power station (S1690). The low power communication operation according to the TWT function may be performed as follows. The low power communication operation according to the TWT function may be performed in two ways. In method # 1, a WUR wakeup frame may be used, and in method # 2, a WUR wakeup frame may not be used.

-Method # 1

19 is a timing diagram illustrating a first embodiment of a low power communication operation according to a TWT function in a WLAN based communication system.

Referring to FIG. 19, the WURx of the low power station may operate in a wake-up state at on duration within a WUR duty cycle period, and may operate in a sleep state at a time excluding on duration among the WUR duty cycle periods. The access point may transmit the WUR wakeup frame 1901 in on duration within the WUR duty cycle period. The WUR wakeup frame 1901 may be transmitted in consideration of the wakeup delay time of the PCR of the low power station. For example, the access point may transmit the WUR wakeup frame 1901 before the wakeup delay time from a preset TWT between the access point and the low power station. The wakeup delay time may be the time required for the PCR of the low power station to transition from the sleep state to the wake up state.

The WURx of the low power station may receive the WUR wakeup frame 1901 from the access point. When the WUR wakeup frame 1901 is received from an access point, the PCR of the low power station may wake up. For example, the processor (or WURx) of the low power station may send a wake up interrupt signal to the PCR of the low power station. When a wakeup interrupt signal is received from the low power station's processor (or WURx), the PCR of the low power station may transition from a sleep state to a wake up state in the TWT and remain a wake up state during the TWT SP.

The access point may send a trigger frame 1902 to the low power station that triggers uplink transmission after TWT. Alternatively, transmission of the trigger frame 1902 may be omitted. The trigger frame 1902 may include an identifier of a low power station, information indicating a resource used for uplink transmission, and the like. In addition, the trigger frame 1902 may include information indicating the TWT SP. If the amount of data to be sent to the low power station is large, the TWT SP may be set relatively long. On the other hand, when the amount of data to be transmitted to the low power station is small, the TWT SP may be set relatively short.

Meanwhile, when the amount of data to be transmitted to the power station is large, the end point of the TWT SP may be later than the end point of the corresponding WUR duty cycle period. In this case, the trigger frame 1902 indicates that the on-duration of the next WUR duty cycle period is not used in succession with the current WUR duty cycle period (eg, the WUR duty cycle period in which the trigger frame 1902 was received). May contain information. In this case, the WURx included in the low power station may remain in a sleep state during the next WUR duty cycle period.

The PCR of the low power station may receive the trigger frame 1902 from the access point and operate based on the information contained in the trigger frame 1902. For example, the PCR of the low power station may send uplink frame 1903 to the access point. The access point may receive the uplink frame 1903 from the PCR of the low power station. The access point may also send downlink frame 1904 to the PCR of the low power station. The PCR of the low power station may receive the downlink frame 1904 from the access point. If the downlink frame 1904 is successfully received, the PCR of the low power station may send an ACK frame 1905 to the access point. If the ACK frame 1905 is received from the PCR of the low power station, the access point may determine that the downlink frame 1904 was successfully received from the PCR of the low power station. Here, the PCR of the low power station may maintain a wake up state during the TWT SP indicated by the second frame, the WUR mode grant frame, or the trigger frame 1902.

-Method # 2

20 is a timing diagram illustrating a second embodiment of a low power communication operation according to a TWT function in a WLAN-based communication system.

Referring to FIG. 20, the WURx of the low power station may operate in a wake-up state in an on duration within a WUR duty cycle period, and may operate in a sleep state at a time other than the on duration in the WUR duty cycle period. Alternatively, when the TWT is preset between the access point and the low power station, the WURx of the low power station may operate in a sleep state at on duration within the WUR duty cycle period. In this case, the WUR wakeup frame may not be transmitted from the access point in on duration.

Meanwhile, the processor (or WURx) of the low power station may transmit the wakeup interrupt signal to the PCR of the low power station in consideration of the wake up delay time of the PCR. The wakeup interrupt signal may be sent from the TWT before the wakeup delay time. When a wakeup interrupt signal is received from the low power station's processor (or WURx), the PCR of the low power station may transition from a sleep state to a wake up state in the TWT and remain a wake up state during the TWT SP.

The access point may send a trigger frame 2001 to the low power station that triggers the uplink transmission after the TWT. Alternatively, transmission of the trigger frame 2001 may be omitted. The trigger frame 2001 may include an identifier of a low power station, information indicating a resource used for uplink transmission, and the like. In addition, the trigger frame 2001 may include information indicating the TWT SP. If the amount of data to be sent to the low power station is large, the TWT SP may be set relatively long. On the other hand, when the amount of data to be transmitted to the low power station is small, the TWT SP may be set relatively short.

Meanwhile, when the amount of data to be transmitted to the power station is large, the end point of the TWT SP may be later than the end point of the corresponding WUR duty cycle. In this case, the trigger frame 2001 indicates that the on-duration of the next WUR duty cycle period is not used in succession with the current WUR duty cycle period (eg, the WUR duty cycle period in which the trigger frame 2001 was received). May contain information. Therefore, the WURx included in the low power station may remain in sleep state on duration within the next WUR duty cycle period.

The PCR of the low power station may receive the trigger frame 2001 from the access point and operate based on the information contained in the trigger frame 2001. For example, the PCR of the low power station may send the uplink frame 2002 to the access point. The access point may receive the uplink frame 2002 from the PCR of the low power station. The access point may also send downlink frame 2003 to the PCR of the low power station. The PCR of the low power station may receive the downlink frame 2003 from the access point. If the downlink frame 2003 is successfully received, the PCR of the low power station may send the ACK frame 2004 to the access point. If the ACK frame 2004 is received from the PCR of the low power station, the access point may determine that the downlink frame 2003 has been successfully received from the PCR of the low power station. Here, the PCR of the low power station may maintain a wake up state during the TWT SP indicated by the second frame, the WUR mode grant frame, or the trigger frame 2001.

■ for multi-user transfer WUR Wake up  frame

Meanwhile, for multi-user transmission, the access point may wake up the plurality of low power stations by transmitting the WUR wakeup frame 900 shown in FIG. 9 a plurality of times. In this case, the performance of the communication system may be degraded due to the transmission of the plurality of WUR wakeup frames 900. In the following, a WUR wakeup frame (hereinafter referred to as a "multi user (UR) WUR wakeup frame") for waking up a plurality of low power stations will be described.

21 is a block diagram illustrating a first embodiment of a WUR frame in a WLAN-based communication system.

Referring to FIG. 21, the WUR frame 2100 may include a preamble (not shown) and a MAC frame. The MAC frame of the WUR frame 2100 may include a MAC header 2110, a frame body 2120, and an FCS field 2130. The MAC frame may include information necessary for operation (eg, information of the low power station, the purpose of the WUR frame 2100, etc.). The MAC header 2110 may include a frame control field 2111, an ID field 2112, and a type dependent (TD) control field 2113. Here, the ID field 2112 may be referred to as an address field. The frame control field 2111 includes a type field 2111-1, a protected field 2111-2, a length present field 2111-3, and a length / miscellaneous field 2111-4. ) May be included.

The type field 211-1 may indicate the type of the WUR frame 2100. The type of WUR frame 2100 may be a WUR beacon frame, a WUR wakeup frame, a WUR vendor specific frame, a WUR discovery frame, or a WUR short wakeup frame. For example, the WUR frame 2100 including the type field 211-1 set to "001" may be a WUR wakeup frame. When the WUR frame 2100 includes a frame body 2120, the length of the frame body 2120 may be indicated by the length present field 2111-3 and the length / other field 2111-4. The length present field 2111-3 may indicate whether the length / other field 2111-4 indicates the length of the frame body 2120.

When the length / other field 2111-4 is set to L, the length of the frame body 2120 may be 2 (L + 1) bytes or 16 (L + 1) bits. Therefore, the frame body 2120 may be set in units of 2 bytes. Information included in the frame body 2120 may vary depending on the type of the WUR frame 2100.

Meanwhile, the MU WUR wake up frame may be used to wake up a plurality of low power stations. In this case, the MU WUR wakeup frame may be generated based on Table 3 below. In Table 3, "-" may be set to a specific value according to the IEEE 802.11ba standard.

The ID field included in the MU WUR wakeup frame may be set to zero. In addition, the length present field included in the MU WUR wakeup frame may be set to 0. In this case, the length / other field included in the MU WUR wakeup frame may indicate the number of LP STAs to be woken up. The frame body of the MU WUR wake-up frame may include IDs of each of the LP STAs to be woken up.

Therefore, when the MU WUR wakeup frame including the ID field set to 0 is received, the low power station may determine that the corresponding MU WUR wakeup frame is used to wake up the plurality of low power stations. The low power station may check the number of IDs included in the frame body (or the length of the frame body) based on the value indicated by the length present field and the length / other field included in the MU WUR wakeup frame. When the ID of the low power station is the same as the ID included in the frame body of the WUR wakeup frame, the PCR included in the low power station may transition from the sleep state to the wakeup state.

On the other hand, some low power stations may not support the decoding function of the MU WUR wakeup frame. Thus, the MU WUR wakeup frame may be sent to a low power station that supports decoding of the MU WUR wakeup frame. Therefore, a procedure for exchanging a function (eg, a decoding function of the MU WUR wakeup frame) supported by the low power station may be performed before the transmission procedure of the MU WUR wakeup frame.

For example, the functions supported for the low power station may be exchanged through an access procedure between the access point and the low power station (eg, a procedure for transmitting / receiving a probe request / response frame, a procedure for transmitting / receiving a connection request / response frame, etc.). Alternatively, the functions supported for the low power station may be exchanged through a negotiation procedure for WUR operation (eg, WUR mode) between the access point and the low power station. In this case, the WUR capability information field included in the WUR capability element may be used as follows.

FIG. 22 is a block diagram illustrating a first embodiment of a WUR capability information field in a WLAN based communication system.

Referring to FIG. 22, the WUR capability information field 2200 includes a transition delay field 2210, a variable length WUR frame support field 2220, a WUR group IDs support field 2230, and a protected WUR. Frame support field 2240, 20 MHz WUR basic PPDU field 2250 with high data rate (HDR) support, WUR channel switching support field 2260, multiple WIDs support field 2270, and spare field 2280 ) May be included. Alternatively, the WUR capability information field 2200 may include a WUR FDMA support field or a WUR short wakeup frame support field instead of the WUR channel switching support field 2260.

Multiple WIDs support field 2270 may be used to indicate whether the low power station supports decoding of the MU WUR wakeup frame. The multiple WIDs support field 2270 set to 0 may indicate that the corresponding low power station does not support the decoding function of the MU WUR wakeup frame. The multiple WIDs support field 2270 set to 1 may indicate that the corresponding low power station supports the decoding function of the MU WUR wakeup frame. In this case, the VL WUR frame support field 2220 may be set to one.

Meanwhile, the length field of the MU WUR wakeup frame may be set to zero. Even in this case, the MU WUR wake-up frame may include a frame body. When the length field of the MU WUR wakeup frame is set to 0, the length / other field may indicate the number of low power stations that are the wakeup target. For example, the length / other field of the MU WUR wakeup frame may be set to "the number of low power stations to be woken-1". In this case, the maximum number of low power stations waked up by the MU WUR wakeup frame may be eight. Alternatively, the length / other field of the MU WUR wakeup frame may be set to "the number of low power stations to be woken-2". In this case, the maximum number of low power stations waked up by the MU WUR wakeup frame may be nine.

When the length / other field of the MU WUR wake-up frame is "the number of low power stations to be woken-1" and the number of the low power stations to be woken is 1, the length / other field may be set to zero. In this case, the ID field of the MU WUR wake-up frame may be set to the ID of the low power station to be woken up, and the MU WUR wake-up frame may not include the frame body.

If the length / other field of the MU WUR wake-up frame is "Number of low power stations to be woken-1" and the number of low power stations to be woken is 2 or more, the ID of each of the low power stations to be woken up is included in the frame body. Can be.

If the length / other field of the MU WUR wake-up frame is "Number of low power stations to wake up-2" and the length / other field is set to 0, the number of low power stations to wake up (eg, 1 or 2). May be unclear. In this case, if the ID field of the MU WUR wakeup frame is set to 0, the low power station may interpret that the frame body of the MU WUR wakeup frame includes the ID of each of the two low power stations.

On the other hand, the length of the frame body of the MU WUR wake-up frame may be proportional to the number of low-power stations to be woken up. The frame body of the MU WUR wake-up frame may be set as follows.

FIG. 23 is a block diagram illustrating a first embodiment of an MU WUR wakeup frame in a WLAN-based communication system.

Referring to FIG. 23, the MU WUR wakeup frame 2300 may include a preamble (not shown), a MAC header 2310, a frame body 2320, and an FCS field 2330. The frame body 2320 may include one or more sub ID fields. In addition, the frame body 2320 may further include a padding bit as necessary. One sub ID field may indicate an ID of one low power station. The size of one sub ID field may be 12 bits.

Meanwhile, the padding bit of the frame body may be set according to the number of low power stations to be woken up. For example, the size of the frame body and the size of the padding bits may be determined based on Table 4 below.

When the number of low power stations to be woken up is 3 or 4, the exact structure of the frame body may not be identified by the length present field and the length / other field. Also, when the number of low power stations to be woken up is 7 or 8, the exact structure of the frame body may not be identified by the length present field and the length / other field. In this case, if the decoding result of the specific portion of the frame body is a padding bit, the low power station may determine that the specific portion of the frame body is not the sub ID field. Here, the padding bit may be configured as zero. For example, if the length / other field of the MU WUR wake-up frame is set to 2, the low power station may obtain three IDs by decoding the frame body, and consider the bits set to 0 as padding bits. .

On the other hand, when the frame body is set in units of 1 byte and the number of low power stations to be woken is odd, the size of the padding bits included in the frame body may be 4 bits. When the frame body is set in units of 1 byte and the number of low power stations to be woken up is even, the frame body may not include padding bits. Alternatively, when the frame body is set in bits, the frame body may not include padding bits.

Meanwhile, the TD control field included in the MU WUR wakeup frame may be used as a sub ID field. When the number of low power stations to be woken up is 2 or more, the ID of one low power station may be included in the TD control field of the MU WUR wakeup frame, and the ID of the remaining low power stations may be included in the frame body of the MU WUR wakeup frame. have. In this case, the size of the frame body can be reduced.

■ MU WUR Wake up  Frame included in the frame Body  Size Instruction Method

The size of the frame body of the MU WUR wakeup frame may be indicated by the TD control field. For example, the MU WUR wakeup frame may be set based on Table 5 below. "-" In Table 5 may be set to a specific value according to the IEEE 802.11ba standard.

If the length present field is set to 1 and the length / other field is set to 0, the TD control field may be used to indicate the size of the frame body. When the maximum size of the frame body is set, specific bits in the TD control field may be used to indicate the size of the frame body, and other bits except for specific bits in the TD control field may be used for other purposes. For example, if the maximum size of the frame body is 16 octets, the preceding 7 bits or 8 bits in the TD control field may be used to indicate the size of the frame body. When the frame body is set in units of bits, the TD control field may be set to "size of the frame body + 1".

Alternatively, the TD control field may be used to indicate the number of low power stations that are a wake-up target. When the maximum number of low power stations to be woken up is set, specific bits in the TD control field may be used to indicate the number of low power stations, and the remaining bits except for specific bits in the TD control field may be used for other purposes. For example, the preceding 3 bits or 4 bits in the TD control field may be used to indicate the number of low power stations. The TD control field may be set to "number of low power stations + 1". Or, if the length / other field is set to 0 and the TD control field is set to 0, the low power station may interpret that the length of the frame body is 2 octets.

Meanwhile, when the MU WUR wakeup frame is set in octet units, the TD control field may indicate the size of the frame body in octet units. In this case, padding bits may be included in the frame body, and the length of the padding bits may be 4 bits.

If the TD control field indicates the size of the frame body in octets and the maximum size of the frame body is set, specific bits in the TD control field may be used to indicate the size of the frame body, and specific bits in the TD control field may be used. The remaining bits can be used for other purposes. For example, if the maximum size of the frame body is 16 octets, 4 bits or 5 bits in the TD control field may be used to indicate the size of the frame body. The TD control field may be set to "size of frame body + 1". Or, if the length / other field is set to 0 and the TD control field is set to 0, the low power station may interpret that the size of the frame body is 2 octets.

Meanwhile, the above-described MU WUR wakeup frame may be introduced in the embodiment shown in FIG. 19. In this case, the access point may transmit the MU WUR wakeup frame 1901 instead of the WUR wakeup frame that wakes up one low power station. The WURx of the low power station may receive the MU WUR wakeup frame 1901 and may wake up the PCR if the ID of the low power station is the same as the ID included in the frame body of the MU WUR wakeup frame 1901. .

The methods according to the invention can be implemented in the form of program instructions that can be executed by various computer means and recorded on a computer readable medium. Computer-readable media may include, alone or in combination with the program instructions, data files, data structures, and the like. The program instructions recorded on the computer readable medium may be those specially designed and constructed for the present invention, or may be known and available to those skilled in computer software.

Examples of computer readable media include hardware devices that are specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code, such as produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate with at least one software module to perform the operations of the present invention, and vice versa.

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

Claims (20)

As a low power station in a communication system,
A processor;
A memory in which one or more instructions executed by the processor are stored;
A receiver for receiving a wake-up radio (WUR) physical protocol data unit (PPDU) in accordance with the one or more instructions; And
A transceiver for transmitting and receiving legacy PPDUs in accordance with the one or more instructions,
The receiver receives a WUR wakeup frame from an access point in on duration within a wake-up radio (WUR) duty cycle period;
If the WUR wakeup frame is received, the processor sends a first signal to the transceiver requesting wakeup; And
A low power station, executed when the first signal is received, the transceiver transitions from a sleep state to a wake-up state at a target wake time set between the access point and the low power station . The method according to claim 1,
The one or more instructions,
And further executes to transmit to the access point first information indicating that the low power station supports TWT functionality. The method according to claim 1,
The one or more instructions,
The low power station is further executed to send second information to the access point requesting to perform a TWT operation, the second information being transmitted in a negotiation procedure for the WUR mode between the access point and the low power station. . The method according to claim 1,
The one or more instructions,
And wherein the transceiver is further executed to maintain the wake up state for a TWT service period (SP) established between the access point and the low power station. The method according to claim 4,
The TWT and the TWT SP are established in a negotiation procedure for a WUR mode between the access point and the low power station. The method according to claim 4,
The one or more instructions,
The transceiver sends and receives the legacy PPDU with the access point during the TWT SP; And
A low power station, further executed to transition the transceiver from the wake up state to the sleep state when the TWT SP is terminated; The method according to claim 1,
And the WUR wakeup frame is received from the TWT before the wakeup delay time of the transceiver. The method according to claim 1,
The legacy PPDU is a non-high throughput (DU) HT PPDU, an HT PPDU, a very high throughput (DUT) PPDU, or a high efficiency (DU) PPDU. The method according to claim 1,
The WUR wake up frame is used to wake up a plurality of low power stations and includes an identifier of each of the plurality of low power stations. The method according to claim 9,
The medium access control (MAC) header of the WUR wakeup frame further includes information indicating the number of the plurality of low power stations, and the ID of each of the plurality of low power stations is a frame body of the WUR wakeup frame. low power station). As a low power station in a communication system,
A processor;
A memory in which one or more instructions executed by the processor are stored;
A receiver for receiving a wake-up radio (WUR) physical protocol data unit (PPDU) in accordance with the one or more instructions; And
A transceiver for transmitting and receiving legacy PPDUs in accordance with the one or more instructions,
The processor sends a first signal to the transceiver requesting a wakeup from a target wake time (TWT) set between the access point and the low power station;
When the first signal is received, the transceiver transitions from a sleep state to a wake-up state in the TWT; And
And wherein the transceiver is executed to maintain the wake-up state for a set TWT service period (SP) between the access point and the low power station. The method according to claim 11,
The one or more instructions,
And further executes to transmit to the access point first information indicating that the low power station supports TWT functionality. The method according to claim 11,
The one or more instructions,
The low power station is further executed to send second information to the access point requesting to perform a TWT operation, the second information being transmitted in a negotiation procedure for the WUR mode between the access point and the low power station. . The method according to claim 11,
The TWT and the TWT SP are established in a negotiation procedure for a WUR mode between the access point and the low power station. The method according to claim 11,
The one or more instructions,
The transceiver sends and receives the legacy PPDU with the access point during the TWT SP; And
The transceiver is further executed to transition from the wake up state to the sleep state when the TWT SP is terminated. The method according to claim 11,
The WUR wakeup frame is used to wake up a plurality of low power stations, the medium access control (MAC) header of the WUR wakeup frame includes information indicating the number of the plurality of low power stations, and the WUR wakeup The frame body of the frame includes an identifier of each of the plurality of low power stations. A method of operating an access point in a communication system,
Receiving a wake-up radio (WUR) mode request frame from the low power station, the WUR mode request frame including first information requesting to perform a target wake time (TWT) operation;
Transmitting a WUR mode response frame to the low power station, the WUR mode response frame including second information indicating that the performance of the TWT operation has been approved; And
Transmitting a WUR wakeup frame to the low power station from a TWT before the wake up delay time of the low power station. The method according to claim 17,
The WUR mode response frame further includes third information indicating the TWT and fourth information indicating a TWT service period (SP). The method according to claim 18,
The operation method of the access point,
Transmitting and receiving a legacy physical protocol data unit (PPDU) with the low power station during the TWT SP;
The legacy PPDU is a non-high throughput (DU) HT PPDU, an HT PPDU, a very high throughput (DUT) PPDU, or a high efficiency (DU) PPDU. The method according to claim 17,
The WUR wakeup frame is used to wake up a plurality of low power stations, the medium access control (MAC) header of the WUR wakeup frame includes information indicating the number of the plurality of low power stations, and the WUR wakeup The frame body of the frame includes an identifier of each of the plurality of low power stations.

Images