WO2019212250A1 - Method and device for transmitting wakeup packet in wireless lan system - Google Patents

Abstract

Proposed are a method and device for transmitting a wakeup packet in a wireless LAN system. Specifically, a transmission device applies an OOK method to generate the wakeup packet. The transmission device transmits the wakeup packet to a receiving device through an 80MHz channel. The 80MHz channel includes first to fourth sub-channels. The wakeup packet includes a first PPDU transmitted through the first sub-channel. When a wakeup packet for the receiving device in the first sub-channel is not present, the first PPDU includes a wakeup null frame and a padding symbol. The wakeup null frame and the padding symbol are transmitted in a first frequency band related to 13 consecutive sub-carriers in the first sub-channel. The first sub-channel is a primary channel of the 80 MHz channel.

Description

Method and apparatus for transmitting wake-up packet in WLAN system

The present disclosure relates to a technique for performing low power communication in a WLAN system, and more particularly, to a method and apparatus for transmitting a wake-up packet by applying a OOK scheme in a WLAN system.

Discussion is underway for the next generation wireless local area network (WLAN). In next-generation WLANs, 1) enhancements to the Institute of Electronics and Electronics Engineers (IEEE) 802.11 physical physical access (PHY) and medium access control (MAC) layers in the 2.4 GHz and 5 GHz bands, and 2) spectral efficiency and area throughput. aims to improve performance in real indoor and outdoor environments, such as in environments where interference sources exist, dense heterogeneous network environments, and high user loads.

The environment mainly considered in the next-generation WLAN is a dense environment having many access points (APs) and a station (STA), and improvements in spectral efficiency and area throughput are discussed in such a dense environment. In addition, in the next generation WLAN, there is an interest in improving practical performance not only in an indoor environment but also in an outdoor environment, which is not much considered in a conventional WLAN.

Specifically, in the next-generation WLAN, there is a great interest in scenarios such as wireless office, smart home, stadium, hotspot, building / apartment, and AP based on the scenario. And STA are discussing about improving system performance in a dense environment with many STAs.

In addition, in the next-generation WLAN, there will be more discussion about improving system performance in outdoor overlapping basic service set (OBSS) environment, improving outdoor environment performance, and cellular offloading, rather than improving single link performance in one basic service set (BSS). It is expected. The directionality of these next-generation WLANs means that next-generation WLANs will increasingly have a technology range similar to that of mobile communications. Considering the recent situation in which mobile communication and WLAN technology are discussed together in the small cell and direct-to-direct (D2D) communication area, the technical and business convergence of next-generation WLAN and mobile communication is expected to become more active.

The present specification proposes a method and apparatus for transmitting a wake-up packet by applying a OOK scheme in a WLAN system.

An example of the present specification proposes a method and apparatus for transmitting a wake-up packet to a WLAN system.

This embodiment is performed in a transmitter, the receiver may correspond to a low power wake-up receiver, and the transmitter may correspond to an AP. This embodiment describes a case in which a wake-up packet transmitted to wake up a primary radio is transmitted to a plurality of receivers through a wide bandwidth or multi-channel.

The transmission of the WUR PPDU over a wide bandwidth means that the WUR PPDU per 20 MHz band within a wide bandwidth is transmitted by applying a frequency division multiplexing access (FDMA) scheme. Therefore, this embodiment can be said that WUR FDMA is applied.

In addition, the present embodiment assumes that a broadband is a band for an 80 MHz channel, and if there is no STA to wake up through a WUR on the primary channel among the 80 MHz channels or there is no pending wakeup packet to transmit, A new definition proposes a method of preventing a collision due to channel access of a third party STA.

First of all, the term “on signal” may correspond to a signal having an actual power value. The off signal may correspond to a signal that does not have an actual power value.

The transmitter generates a wake-up packet by applying an On-Off Keying (OOK) method.

The transmitter transmits the wakeup packet to the receiver through an 80 MHz channel.

How the wakeup packet is configured in the present embodiment is as follows.

The 80 MHz channel includes first to fourth subchannels.

The wakeup packet includes a first PHY protocol data unit (PPDU) transmitted on the first subchannel.

If there is no wakeup packet for the receiver in the first subchannel (if there is no receiver to wake up through the wakeup packet in the first subchannel), the first PPDU is a wakeup null. Frame includes a wake-up null frame and a padding symbol. That is, even if there is no pending wakeup packet in the first subchannel, the state of the first subchannel may be made busy by transmitting the wakeup null frame and the padding symbol. As a result, a third party STA (inter STA or intra STA) may determine that the first subchannel is busy until the wakeup null frame and the padding symbol length, and suspend data transmission.

The wakeup null frame and the padding symbol are transmitted in a first frequency band associated with 13 consecutive subcarriers in the first subchannel. The first frequency band may be a 4 MHz band.

The first subchannel is a primary channel of the 80 MHz channel.

The wake-up null frame may include a frame control field and a FCS field. However, the wakeup null frame may not include an address field, a type dependent control field, and a frame body field.

The frame control field may include a type subfield and a length subfield.

The type subfield may include information that the type of the first PPDU is the wakeup null frame.

The length subfield may include information about the length of the first PPDU.

As a result, the receiving device receiving the wake-up null frame may decode the frame control field and the FCS field. In addition, the receiving apparatus receiving the wake-up null frame detects the type subfield to know that the received frame is the wake-up null frame, and detects the length subfield to pad the padding symbol to a certain point. I can see that.

The wakeup packet may further include a second PPDU transmitted in the second subchannel, a third PPDU transmitted in the third subchannel, and a fourth PPDU transmitted in a fourth subchannel.

The padding symbol may be padded such that the length of the first PPDU is equal to the maximum length of the lengths of the second to fourth PPDUs.

When there is a wakeup signal for the receiver in the second subchannel, the second PPDU may include a first wakeup frame. The first wakeup frame may be generated by inserting a first sequence into 13 consecutive subcarriers in the second subchannel and performing an inverse fast fourier transform (IFFT).

When the wakeup signal for the receiver is present in the third subchannel, the third PPDU may include a second wakeup frame. The second wakeup frame may be generated by inserting a second sequence into 13 consecutive subcarriers in the third subchannel and performing IFFT.

When the wakeup signal for the receiver is present in the fourth subchannel, the fourth PPDU may include a third wakeup frame. The third wakeup frame may be generated by inserting a third sequence into 13 consecutive subcarriers in the fourth subchannel and performing IFFT.

The receiving device may include first to fourth STAs. The first STA may not support a wake-up receiver (WUR). That is, the first STA is not an STA to be woken through the WUR. The second to fourth STAs support WUR. That is, the second to fourth STAs are STAs that wake up through the WUR.

The first PPDU may be transmitted in the first subchannel for the first STA. The second PPDU may be transmitted in the second subchannel for the second STA. The third PPDU may be transmitted in the third subchannel for the third STA. The fourth PPDU may be transmitted in the fourth subchannel for the fourth STA.

The first STA receives the first PPDU in the first subchannel, and determines that the first PPDU is the wakeup null frame through the type subfield. The first STA sleeps by the length of the first PPDU through the length subfield. Accordingly, the first STA may determine that the first subchannel is busy while the first PPDU is transmitted and suspend data transmission and reception. After the first PPDU is transmitted, the first STA may perform channel access to the first subchannel to perform data transmission and reception.

Each of the first to fourth subchannels may be a 20 MHz channel.

The wakeup null frame may have a first data rate or second data. The first data rate may be 62.5 kb / s, and the second data rate may be 250 kb / s.

Channel access for each subchannel is described as follows.

Channel access for the first to fourth subchannels may be performed during a Point Coordination Function (PCF) Interframe Space (PIFS) section immediately before the transmission opportunity (TXOP) starts. The wakeup packet may be transmitted during the TXOP.

Further, when the first to fourth subchannels are idle as a result of performing the channel access, the transmitter may determine whether the pending wakeup packet is present in the first to fourth subchannels.

The first to third sequences may be set to 13 length sequences, 7 length sequences, or the like based on the data rate. The IFFT may be a 64 point IFFT.

In addition, the transmitter may first configure power values of the on signal and the off signal, and configure the on signal and the off signal. The receiver decodes the on signal and the off signal using an envelope detector, thereby reducing power consumed in decoding.

According to the exemplary embodiment of the present specification, the wakeup packet is configured and transmitted by applying the OOK modulation scheme in the transmitter to reduce power consumption by using an envelope detector during wakeup decoding in the receiver. Therefore, the receiving device can decode the wakeup packet to the minimum power.

In addition, according to an example of the present specification, when there is no STA to wake up through the WUR in the primary channel among the 80 MHz channels or there is no pending wakeup packet to transmit, a specific frame is newly defined in the primary channel to form a third frame. By preventing a collision due to channel access of an STA, channel efficiency may be increased.

1 is a conceptual diagram illustrating a structure of a wireless local area network (WLAN).

2 is a diagram illustrating an example of a PPDU used in the IEEE standard.

3 is a diagram illustrating an example of a HE PPDU.

4 illustrates a low power wake-up receiver in an environment in which data is not received.

5 illustrates a low power wake-up receiver in an environment in which data is received.

6 shows an example of a wakeup packet structure according to the present embodiment.

7 shows a signal waveform of a wakeup packet according to the present embodiment.

FIG. 8 is a diagram for describing a principle in which power consumption is determined according to a ratio of 1 and 0 of bit values constituting binary sequence information using the OOK method.

9 shows a method of designing a OOK pulse according to the present embodiment.

10 is an explanatory diagram of a Manchester coding scheme according to the present embodiment.

11 illustrates various examples of a symbol repetition technique of repeating n symbols according to the present embodiment.

12 illustrates various examples of a symbol reduction technique according to the present embodiment.

FIG. 13 shows an example of configuring a 2us on signal based on signal masking according to the present embodiment.

14 illustrates an example of a wakeup packet structure to which a sync part according to the present embodiment is applied.

15 shows an example of a wakeup packet structure transmitted through the 40 MHz band according to the present embodiment.

16 illustrates an example of a wakeup packet structure transmitted through an 80 MHz band according to the present embodiment.

17 shows an example of a wakeup packet structure transmitted through the 160MHz band according to the present embodiment.

18 shows an example of a WUR frame format according to the present embodiment.

19 shows an example of collision occurring in the primary channel according to the present embodiment.

20 illustrates an example of suspending transmission of a wake-up frame in the secondary channel until transmission of the wake-up frame in the primary channel according to the present embodiment.

21 shows an example of a WUR null frame format excluding FCS according to the present embodiment.

22 shows an example of using a WUR null frame according to the present embodiment.

23 shows an example of a WUR null frame format including an FCS according to the present embodiment.

24 shows another example utilizing the WUR null frame according to the present embodiment.

25 shows an example of transmitting a PCR PPDU simultaneously with a WUR frame according to the present embodiment.

26 is a flowchart illustrating a procedure of transmitting a wake-up packet by applying the OOK method according to the present embodiment.

27 is a flowchart illustrating a procedure of receiving a wake-up packet by applying the OOK scheme according to the present embodiment.

FIG. 28 is a diagram for explaining an apparatus for implementing the method as described above.

29 illustrates a more detailed wireless device implementing an embodiment of the present invention.

1 is a conceptual diagram illustrating a structure of a wireless local area network (WLAN).

1 shows the structure of the infrastructure basic service set (BSS) of the Institute of Electrical and Electronic Engineers (IEEE) 802.11.

Referring to the top of FIG. 1, the WLAN system may include one or more infrastructure BSSs 100 and 105 (hereinafter, BSS). The BSSs 100 and 105 are a set of APs and STAs such as an access point 125 and a STA1 (station 100-1) capable of successfully synchronizing and communicating with each other, and do not indicate a specific area. The BSS 105 may include one or more joinable STAs 105-1 and 105-2 to one AP 130.

The BSS may include at least one STA, APs 125 and 130 for providing a distribution service, and a distribution system (DS) 110 for connecting a plurality of APs.

The distributed system 110 may connect several BSSs 100 and 105 to implement an extended service set (ESS) 140 which is an extended service set. The ESS 140 may be used as a term indicating one network in which one or several APs 125 and 230 are connected through the distributed system 110. APs included in one ESS 140 may have the same service set identification (SSID).

The portal 120 may serve as a bridge for connecting the WLAN network (IEEE 802.11) with another network (for example, 802.X).

In the BSS as shown in the upper part of FIG. 1, a network between the APs 125 and 130 and a network between the APs 125 and 130 and the STAs 100-1, 105-1 and 105-2 may be implemented. However, it may be possible to perform communication by setting up a network even between STAs without the APs 125 and 130. A network that performs communication by establishing a network even between STAs without APs 125 and 130 is defined as an ad-hoc network or an independent basic service set (BSS).

1 is a conceptual diagram illustrating an IBSS.

Referring to the bottom of FIG. 1, the IBSS is a BSS operating in an ad-hoc mode. Since IBSS does not contain an AP, there is no centralized management entity. That is, in the IBSS, the STAs 150-1, 150-2, 150-3, 155-4, and 155-5 are managed in a distributed manner. In the IBSS, all STAs 150-1, 150-2, 150-3, 155-4, and 155-5 may be mobile STAs, and access to a distributed system is not allowed, thus making a self-contained network. network).

A STA is any functional medium that includes medium access control (MAC) conforming to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard and a physical layer interface to a wireless medium. May be used to mean both an AP and a non-AP STA (Non-AP Station).

The STA may include a mobile terminal, a wireless device, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile subscriber unit ( It may also be called various names such as a mobile subscriber unit or simply a user.

On the other hand, the term "user" may be used in various meanings, for example, may also be used to mean an STA participating in uplink MU MIMO and / or uplink OFDMA transmission in wireless LAN communication. It is not limited to this.

2 is a diagram illustrating an example of a PPDU used in the IEEE standard.

As shown, various types of PHY protocol data units (PPDUs) have been used in the IEEE a / g / n / ac standard. Specifically, the LTF and STF fields included training signals, the SIG-A and SIG-B included control information for the receiving station, and the data fields included user data corresponding to the PSDU.

This embodiment proposes an improved technique for the signal (or control information field) used for the data field of the PPDU. The signal proposed in this embodiment may be applied on a high efficiency PPDU (HE PPDU) according to the IEEE 802.11ax standard. That is, the signals to be improved in the present embodiment may be HE-SIG-A and / or HE-SIG-B included in the HE PPDU. Each of HE-SIG-A and HE-SIG-B may also be represented as SIG-A or SIG-B. However, the improved signal proposed by this embodiment is not necessarily limited to the HE-SIG-A and / or HE-SIG-B standard, and controls / control of various names including control information in a wireless communication system for transmitting user data. Applicable to data fields.

3 is a diagram illustrating an example of a HE PPDU.

The control information field proposed in this embodiment may be HE-SIG-B included in the HE PPDU as shown in FIG. 3. The HE PPDU according to FIG. 3 is an example of a PPDU for multiple users. The HE-SIG-B may be included only for the multi-user, and the HE-SIG-B may be omitted in the PPDU for the single user.

As shown, a HE-PPDU for a multiple user (MU) includes a legacy-short training field (L-STF), a legacy-long training field (L-LTF), a legacy-signal (L-SIG), High efficiency-signal A (HE-SIG-A), high efficiency-signal-B (HE-SIG-B), high efficiency-short training field (HE-STF), high efficiency-long training field (HE-LTF) It may include a data field (or MAC payload) and a PE (Packet Extension) field. Each field may be transmitted during the time period shown (ie, 4 or 8 ms, etc.).

The PPDU used in the IEEE standard is mainly described as a PPDU structure transmitted over a channel bandwidth of 20 MHz. The PPDU structure transmitted on a bandwidth wider than the channel bandwidth of 20 MHz (eg, 40 MHz and 80 MHz) may be a structure in which linear scaling of the PPDU structure used in the channel bandwidth of 20 MHz is applied.

The PPDU structure used in the IEEE standard is generated based on 64 Fast Fourier Tranforms (FTFs), and a CP portion (cyclic prefix portion) may be 1/4. In this case, the length of the effective symbol interval (or FFT interval) may be 3.2us, the CP length is 0.8us, and the symbol duration may be 4us (3.2us + 0.8us) plus the effective symbol interval and the CP length.

Wireless networks are ubiquitous, usually indoors and often installed outdoors. Wireless networks use various techniques to send and receive information. For example, but not limited to, two widely used technologies for communication are those that comply with IEEE 802.11 standards such as the IEEE 802.11n standard and the IEEE 802.11ac standard.

The IEEE 802.11 standard specifies a common Medium Access Control (MAC) layer that provides a variety of features to support the operation of IEEE 802.11-based wireless LANs (WLANs). The MAC layer utilizes protocols that coordinate access to shared radios and improve communications over wireless media, such as IEEE 802.11 stations (such as a PC's wireless network card (NIC) or other wireless device or station (STA) and access point ( Manage and maintain communication between APs).

IEEE 802.11ax is the successor to 802.11ac and has been proposed to improve the efficiency of WLAN networks, especially in high density areas such as public hotspots and other high density traffic areas. IEEE 802.11 can also use Orthogonal Frequency Division Multiple Access (OFDMA). The High Efficiency WLAN Research Group (HEW SG) within the IEEE 802.11 Work Group is dedicated to improving system throughput / area in high-density scenarios of APs (access points) and / or STAs (stations) in relation to the IEEE 802.11 standard. We are considering improving efficiency.

Wearable devices and small computing devices such as sensors and mobile devices are constrained by small battery capacities, but use wireless communication technologies such as Wi-Fi, Bluetooth®, and Bluetooth® Low Energy (BLE). Support, connect to and exchange data with other computing devices such as smartphones, tablets, and computers. Since these communications consume power, it is important to minimize the energy consumption of such communications in these devices. One ideal strategy to minimize energy consumption is to power off the communication block as frequently as possible while maintaining data transmission and reception without increasing delay too much. That is, the communication block is transmitted immediately before the data reception, and only when there is data to wake up, the communication block is turned on and the communication block is turned off for the remaining time.

Hereinafter, a low-power wake-up receiver (LP-WUR) will be described.

The communication system (or communication subsystem) described herein includes a main radio (802.11) and a low power wake up receiver.

The main radio is used for transmitting and receiving user data. The main radio is turned off if there are no data or packets to transmit. The low power wake-up receiver wakes up the main radio when there is a packet to receive. At this time, the user data is transmitted and received by the main radio.

The low power wake-up receiver is not for user data. It is simply a receiver to wake up the main radio. In other words, the transmitter is not included. The low power wake-up receiver is active while the main radio is off. Low power wake-up receivers target a target power consumption of less than 1 mW in an active state. In addition, low power wake-up receivers use a narrow bandwidth of less than 5 MHz. In addition, the target transmission range of the low power wake-up receiver is the same as that of the existing 802.11.

4 illustrates a low power wake-up receiver in an environment in which data is not received. 5 illustrates a low power wake-up receiver in an environment in which data is received.

As shown in Figures 4 and 5, if there is data to be transmitted and received, one way to implement an ideal transmission and reception strategy is a main radio such as Wi-Fi, Bluetooth® radio, or Bluetooth® Radio (BLE). Adding a low power wake-up receiver (LP-WUR) that can wake up.

Referring to FIG. 4, the Wi-Fi / BT / BLE 420 is turned off and the low power wake-up receiver 430 is turned on without receiving data. Some studies show that the low power wake-up receiver (LP-WUR) can consume less than 1mW.

However, as shown in FIG. 5, when a wakeup packet is received, the low power wakeup receiver 530 may receive the entire Wi-Fi / BT / BLE radio 520 so that the data packet following the wakeup packet can be correctly received. Wake up). In some cases, however, actual data or IEEE 802.11 MAC frames may be included in the wakeup packet. In this case, it is not necessary to wake up the entire Wi-Fi / BT / BLE radio 520, but only a part of the Wi-Fi / BT / BLE radio 520 to perform the necessary process. This can result in significant power savings.

One example technique disclosed herein defines a method for a granular wakeup mode for Wi-Fi / BT / BLE using a low power wakeup receiver. For example, the actual data contained in the wakeup packet can be passed directly to the device's memory block without waking up the Wi-Fi / BT / BLE radio.

As another example, if a wakeup packet contains an IEEE 802.11 MAC frame, only the MAC processor of the Wi-Fi / BT / BLE wireless device needs to wake up to process the IEEE 802.11 MAC frame included in the wakeup. That is, the PHY module of the Wi-Fi / BT / BLE radio can be turned off or kept in a low power mode.

A number of granular wakeup modes have been defined for Wi-Fi / BT / BLE radios that use low power wake-up receivers, requiring that the Wi-Fi / BT / BLE radio be powered on when a wake-up packet is received. However, according to the above embodiment, only necessary parts (or components) of the Wi-Fi / BT / BLE radio can be selectively woken up, thereby saving energy and reducing the waiting time. Many solutions that use low-power wake-up receivers to receive wake-up packets wake up the entire Wi-Fi / BT / BLE radio. One exemplary aspect discussed herein wakes up only the necessary portions of the Wi-Fi / BT / BLE radio required to process the received data, saving significant amounts of energy and reducing unnecessary latency in waking up the main radio. Can be.

In addition, in the above embodiment, the low power wake-up receiver 530 may wake up the main radio 520 based on the wake-up packet transmitted from the transmitter 500.

In addition, the transmitter 500 may be set to transmit a wakeup packet to the receiver 510. For example, the low power wake-up receiver 530 may be instructed to wake up the main radio 520.

6 shows an example of a wakeup packet structure according to the present embodiment.

The wakeup packet may include one or more legacy preambles. One or more legacy devices may decode or process the legacy preamble.

In addition, the wakeup packet may include a payload after the legacy preamble. The payload may be modulated by a simple modulation scheme, for example, an On-Off Keying (OOK) modulation scheme.

Referring to FIG. 6, the transmitter may be configured to generate and / or transmit a wakeup packet 600. The receiving device may be configured to process the received wakeup packet 600.

In addition, the wakeup packet 600 may include a legacy preamble or any other preamble 610 as defined by the IEEE 802.11 specification. In addition, the wakeup packet 600 may include a payload 620.

Legacy preambles provide coexistence with legacy STAs. The legacy preamble 610 for coexistence uses the L-SIG field to protect the packet. The 802.11 STA may detect the start of a packet through the L-STF field in the legacy preamble 610. The 802.11 STA can know the end of the packet through the L-SIG field in the legacy preamble 610. In addition, by adding a BPSK modulated symbol after the L-SIG, a false alarm of an 802.11n terminal can be reduced. One symbol (4us) modulated with BPSK also has a 20MHz bandwidth like the legacy part. The legacy preamble 610 is a field for third party legacy STAs (STAs not including LP-WUR). The legacy preamble 610 is not decoded from the LP-WUR.

The payload 620 may include a wakeup preamble 622. Wake-up preamble 622 may include a sequence of bits configured to identify wake-up packet 600. The wakeup preamble 622 may include, for example, a PN sequence.

In addition, the payload 620 may include a MAC header 624 including address information of a receiver receiving the wakeup packet 600 or an identifier of the receiver.

In addition, the payload 620 may include a frame body 626 that may include other information of the wakeup packet. For example, the frame body 626 may include length or size information of the payload.

In addition, the payload 620 may include a Frame Check Sequence (FCS) field 628 that includes a Cyclic Redundancy Check (CRC) value. For example, it may include a CRC-8 value or a CRC-16 value of the MAC header 624 and the frame body 626.

7 shows a signal waveform of a wakeup packet according to the present embodiment.

Referring to FIG. 7, the wakeup packet 700 includes a legacy preamble (802.11 preamble, 710) and a payload modulated by OOK. That is, the legacy preamble and the new LP-WUR signal waveform coexist.

In addition, the legacy preamble 710 may be modulated according to the OFDM modulation scheme. That is, the legacy preamble 710 is not applied to the OOK method. In contrast, the payload may be modulated according to the OOK method. However, the wakeup preamble 722 in the payload may be modulated according to another modulation scheme.

If the legacy preamble 710 is transmitted on a channel bandwidth of 20 MHz to which 64 FFTs are applied, the payload may be transmitted on a channel bandwidth of about 4.06 MHz. This will be described later in the OOK pulse design method.

First, a modulation scheme using the OOK scheme and a Manchester coding scheme will be described.

FIG. 8 is a diagram for describing a principle in which power consumption is determined according to a ratio of 1 and 0 of bit values constituting binary sequence information using the OOK method.

Referring to FIG. 8, information in the form of a binary sequence having 1 or 0 as a bit value is represented. By using a bit value of 1 or 0 of the binary sequence information, OOK modulation can be performed. That is, in consideration of the bit values of the binary sequence information, it is possible to perform the communication of the OOK modulation method. For example, when the light emitting diode is used for visible light communication, the light emitting diode is turned on when the bit value constituting the binary sequence information is 1, and the light emitting diode is turned off when the bit value is 0. The light emitting diode can be made to blink. As the light-emitting diode blinks, the receiver receives and restores data transmitted in the form of visible light, thereby enabling communication using visible light. However, since the blinking of the light emitting diode cannot be perceived by the human eye, the person feels that the illumination is continuously maintained.

For convenience of description, as shown in FIG. 8, information in the form of a binary sequence having 10 bit values is used. Referring to FIG. 8, there is information in the form of a binary sequence having a value of '1001101011'. As described above, when the bit value is 1, the transmitter is turned on, and when the bit value is 0, the transmitter is turned off, the symbol is turned on at 6 bit values out of 10 bit values. ) do. Therefore, when the symbol is turned on in all 10 bit values, if the power consumption is 100%, the power consumption is 60% according to the duty cycle of FIG. 8.

That is, it can be said that the power consumption of the transmitter is determined according to the ratio of 1 and 0 constituting the binary sequence information. In other words, if there is a constraint that the power consumption of the transmitter must be kept at a certain value, the ratio of 1 and 0, which constitutes information in binary sequence form, must also be maintained. For example, in the case of lighting equipment, since the lighting must be maintained at a specific luminance value desired by people, the ratio of 1 and 0 constituting the information in the form of binary sequence must also be maintained.

However, since the receiver is mainly a wake-up receiver (WUR), the transmission power is not important. The main reason for using OOK is that the power consumption is very low when decoding the received signal. Until the decoding is performed, there is no significant difference in power consumption in the main radio or WUR, but a large difference occurs in the decoding process. Below is the approximate power consumption.

-The existing Wi-Fi power consumption is about 100mW. Specifically, power consumption of Resonator + Oscillator + PLL (1500uW)-> LPF (300uW)-> ADC (63uW)-> decoding processing (OFDM receiver) (100mW) may occur.

-WUR power consumption is about 1mW. Specifically, power consumption of Resonator + Oscillator (600uW)-> LPF (300uW)-> ADC (20uW)-> decoding processing (Envelope detector) (1uW) may occur.

9 shows a method of designing a OOK pulse according to the present embodiment.

The OFDM transmitter of 802.11 can be reused to generate OOK pulses. The transmitter can generate a sequence having 64 bits by applying a 64-point IFFT as in 802.11.

The transmitter should generate the payload of the wakeup packet by modulating the OOK method. However, since the wakeup packet is for low power communication, the OOK method is applied to the ON-signal. The on signal is a signal having an actual power value, and the off signal (OFF-signal) corresponds to a signal having no actual power value. The off signal is also applied to the OOK method, but the signal is not generated using the transmitter, and since no signal is actually transmitted, it is not considered in the configuration of the wakeup packet.

In the OOK method, information (bit) 1 may be an on signal and information (bit) 0 may be an off signal. Alternatively, when the Manchester coding scheme is applied, information 1 may indicate a transition from an off signal to an on signal, and information 0 may indicate a transition from an on signal to an off signal. Alternatively, on the contrary, the information 1 may indicate the transition from the on signal to the off signal, and the information 0 may indicate the transition from the off signal to the on signal. Manchester coding scheme will be described later.

Referring to FIG. 9, as shown in the right frequency domain graph 920, the transmitter applies a sequence by selecting 13 consecutive subcarriers of a 20 MHz band as a reference band as a sample. In FIG. 9, 13 subcarriers located among the subcarriers in the 20 MHz band are selected as samples. That is, a subcarrier whose subcarrier index is from -6 to +6 is selected from the 64 subcarriers. In this case, the subcarrier index 0 may be nulled to 0 as the DC subcarrier. Set a specific sequence only to the 13 subcarriers selected as samples, and set all subcarriers except the subcarriers (subcarrier indexes -32 to -7 and subcarrier indexes +7 to +31) to 0. .

In addition, since subcarrier spacing is 312.5 KHz, 13 subcarriers have a channel bandwidth of about 4.06 MHz. That is, it can be said that power is provided only for 4.06MHz in the 20MHz band in the frequency domain. By moving the power to the center, the signal to noise ratio (SNR) can be increased and the power consumption of the AC / DC converter of the receiver can be reduced. In addition, the power consumption can be reduced by reducing the sampling frequency band to 4.06MHz.

In addition, as shown in the left time domain graph 910 of FIG. 9, the transmitter may generate one on-signal in the time domain by performing a 64-point IFFT on 13 subcarriers. One on-signal has a size of 1 bit. That is, a sequence composed of 13 subcarriers may correspond to 1 bit. On the other hand, the transmitter may not transmit the off signal at all. When performing IFFT, a 3.2us symbol may be generated, and if a CP (Cyclic Prefix, 0.8us) is included, one symbol having a length of 4us may be generated. That is, one bit indicating one on-signal may be loaded in one symbol.

The reason for configuring and sending the bits as in the above-described embodiment is to reduce power consumption by using an envelope detector in the receiver. As a result, the receiving device can decode the packet with the minimum power.

However, the basic data rate for one information may be 125 Kbps (8us) or 62.5Kbps (16us).

Generalizing the above, the signal transmitted in the frequency domain is as follows. That is, each signal having a length of K in the 20 MHz band may be transmitted on K consecutive subcarriers of a total of 64 subcarriers. That is, K may correspond to the bandwidth of the OOK pulse by the number of subcarriers used to transmit a signal. All other coefficients of the K subcarriers are zero. In this case, the indices of the K subcarriers used by the signal corresponding to the information 0 and the information 1 are the same. For example, the subcarrier index used may be represented as 33-floor (K / 2): 33 + ceil (K / 2) -1.

In this case, the information 1 and the information 0 may have the following values.

Information 0 = zeros (1, K)

Information 1 = alpha * ones (1, K)

The alpha is a power normalization factor and may be, for example, 1 / sqrt (K).

10 is an explanatory diagram of a Manchester coding scheme according to the present embodiment.

Manchester coding is a type of line coding, and may indicate information as shown in the following table in a manner in which a transition of a magnitude value occurs in the middle of one bit period.

That is, Manchester coding means a method of converting data from 1 to 01, 0 to 10, 1 to 10, and 0 to 01. Table 1 shows an example in which data is converted from 1 to 10 and 0 to 01 using Manchester coding.

As shown in Fig. 10, the bit string to be transmitted, the Manchester coded signal, the clock reproduced on the receiving side, and the data reproduced on the clock are shown in order from top to bottom.

When the transmitting side transmits data using the Manchester coding scheme, the receiving side reads the data a little later on the basis of the transition point transitioning from 1 → 0 or 0 → 1 and recovers the data, and then transitions to 1 → 0 or 0 → 1. The clock is recovered by recognizing the transition point as the clock transition point. Alternatively, when the symbol is divided based on the transition point, it can be simply decoded by comparing the power at the front and the back at the center of the symbol.

As shown in FIG. 10, the bit string to be transmitted is 10011101, the Manchester coded signal is 0110100101011001, and the clock reproduced by the receiver recognizes the transition point of the Manchester coded signal as the transition point of the clock. Then, the data is recovered by using the reproduced clock.

By using the Manchester coding scheme, it is possible to communicate in a synchronous manner using only a data transmission channel without using a separate clock.

In addition, this method can use the TXD pin for data transmission and the RXD pin for reception by using only the data transmission channel. Therefore, synchronized bidirectional transmission is possible.

This specification proposes various symbol types that can be used in the WUR and thus data rates.

Since STAs requiring robust performance and STAs receiving strong signals from APs are mixed, it is necessary to support efficient data rates in some situations. In order to obtain reliable and robust performance, a symbol coding based symbol coding technique and a symbol repetition technique may be used. In addition, a symbol reduction technique may be used to obtain a high data rate.

In this case, each symbol may be generated using an existing 802.11 OFDM transmitter. In addition, the number of subcarriers used to generate each symbol may be thirteen. However, it is not limited thereto.

In addition, each symbol may use OOK modulation formed of an ON-signal and an OFF-signal.

One symbol generated for the WUR may be composed of a CP (Cyclic Prefix or Guard Interval) and a signal part representing actual information. Symbols having various data rates may be designed by variously setting or repeating the lengths of the CP and the actual information signal.

The following are various examples of symbol types.

For example, the basic WUR symbol may be represented as CP + 3.2us. That is, one bit is represented using a symbol having the same length as the existing Wi-Fi. Specifically, the transmitting apparatus applies a specific sequence to all available subcarriers (for example, 13 subcarriers) and then performs IFFT to form an information signal portion of 3.2 us. In this case, a coefficient of 0 may be loaded on the DC subcarrier or the middle subcarrier index among all available subcarriers.

Different sequences may be applied to the available subcarriers according to the 3.2us on signal and the 3.2us off signal. A 3.2us off signal can be generated by applying all coefficients to zero.

CP may be used by adopting a specific length from the rear of the information signal 3.2us immediately behind. At this time, CP may be 0.4us or 0.8us. This length is equal to the guard interval of 802.11ac.

Accordingly, one bit information corresponding to one basic WUR symbol may be represented as shown in the following table.

Information ‘0’	Information ‘1’
3.2us OFF-signal	3.2us ON-signal

Table 2 does not indicate CP separately. In fact, CP + 3.2us including CP may point to one 1-bit information. That is, the 3.2us on signal can be viewed as a (CP + 3.2us) on signal. A 3.2us off signal can be seen as a (CP + 3.2us) off signal.

As another example, a symbol to which Manchester coding is applied may be represented as CP + 1.6us + CP + 1.6us or CP + 1.6us + 1.6us. The symbol to which the Manchester coding is applied may be generated as follows.

In the OOK transmission using the Wi-Fi transmitter, the time used for transmitting one bit (or symbol) except for the guard interval of the transmission signal is 3.2 us. In this case, if Manchester coding is applied, a signal size transition should occur at 1.6us. That is, each sub-information having a length of 1.6us should have a value of 0 or 1, and may configure a signal in the following manner.

* Information 0-> 1 0 (each can be referred to as sub information 1 0 or sub symbol 1 (ON) 0 (OFF))

First 1.6us (sub information 1 or sub symbol 1): Sub information 1 may have a value of beta * ones (1, K). Beta is a power normalization factor and may be, for example, 1 / sqrt (ceil (K / 2)).

In addition, a specific sequence is applied in units of two squares to all available subcarriers (eg, 13 subcarriers) to generate a symbol to which Manchester coding is applied. That is, even-numbered subcarriers of a particular sequence are nulled to zero. That is, in a particular sequence, coefficients may exist at intervals of two cells. For example, suppose that 13 subcarriers are used to construct an on-signal, a particular sequence with coefficients spaced two spaces apart is {a 0 b 0 c 0 d 0 e 0 f 0 g}, {0 a 0 b 0 c 0 d 0 e 0 f 0} or {a 0 b 0 c 0 0 0 d 0 e 0 method. At this time, a, b, c, d, e, f, g is 1 or -1.

That is, the transmitter maps a specific sequence to K consecutive subcarriers of 64 subcarriers (for example, 33-floor (K / 2): 33 + ceil (K / 2) -1) and the remaining subcarriers. IFFT is performed by setting the coefficient to 0. In this way, signals in the time domain can be generated. The signal in the time domain is a 3.2us long signal having a 1.6us period because coefficients exist at intervals of two columns in the frequency domain. One of the first or second 1.6us period signals can be selected and used as sub information 1.

Second 1.6us (sub information 0 or sub symbol 0): The sub information 0 may have a value of zeros (1, K). Similarly, the transmitter maps a specific sequence to K consecutive subcarriers of 64 subcarriers (eg, 33-floor (K / 2): 33 + ceil (K / 2) -1) and performs IFFT. The signal in the time domain can be generated. The sub information 0 may correspond to a 1.6us off signal. The 1.6us off signal can be generated by setting all coefficients to zero.

One of the first or second 1.6us periodic signals of the signal in the time domain may be selected and used as the sub information 0. You can simply use the zeros (1,32) signal as subinformation zero.

* Information 1-> 0 1 (each can be referred to as sub information '0', '1' or sub symbol 0 (OFF) 1 (ON))

Since information 1 is also divided into the first 1.6us (sub information 0) and the second 1.6us (sub information 1), a signal corresponding to each sub information may be configured in the same manner as the information 0 is generated.

By using a technique of generating information 0 and information 1 using Manchester coding, it is possible to prevent the off symbol from continuing as compared to the conventional method. Therefore, a coexistence problem with an existing Wi-Fi device may not occur. The coexistence problem is a problem caused by transmitting a signal by determining that another device is a channel idle state due to a continuous off symbol. If only OOK modulation is used, for example, the off-symbol may be contiguous with the sequence 100001 or the like, but if Manchester coding is used, the off-symbol cannot be contiguous with the sequence 100101010110.

According to the above description, the sub information may be referred to as a 1.6us information signal. The 1.6us information signal may be a 1.6us on signal or a 1.6 off signal. The 1.6us on signal and the 1.6 off signal may have different sequences applied to each subcarrier.

CP can be used by adopting a specific length from the back of the 1.6us of the information signal immediately after. At this time, CP may be 0.4us or 0.8us. This length is equal to the guard interval of 802.11ac.

Accordingly, one bit information corresponding to one Manchester coded symbol may be represented as shown in the following table.

Information ‘0’	Information ‘1’
1.6us ON-signal + 1.6us OFF-signal	1.6us OFF-signal + 1.6us ON-signal
Or 1.6us OFF-signal + 1.6us ON-signal	Or 1.6us ON-signal + 1.6us OFF-signal

Table 3 does not indicate CP separately. In fact, CP + 1.6us + CP + 1.6us or CP + 1.6us + 1.6us including CP may indicate one 1-bit information. That is, in the former case, the 1.6us on signal and the 1.6us off signal may be regarded as the (CP + 1.6us) on signal and the (CP + 1.6us) off signal.

As another example, a method of constructing a wake-up packet by repeating symbols for performance improvement is proposed.

The symbol repetition technique is applied to the wakeup payload 724. The symbol repetition technique means repetition of a time signal after insertion of an IFFT and a cyclic prefix (CP) of each symbol. Thus, the length (time) of the wakeup payload 724 is doubled.

That is, it is proposed to apply a symbol representing information such as information 0 or information 1 to a specific sequence and to repeat the configuration as follows.

Option 1: Information 0 and Information 1 can be repeatedly represented by the same symbol.

Info 0-> 0 0 (repeat Info 0 twice)

-Info 1-> 1 1 (repeat Info 1 twice)

Option 2: Information 0 and Information 1 can be repeatedly represented by different symbols.

Information 0-> 0 1 or 1 0 (repeat info 0 and info 1)

Info 1-> 1 0 or 0 1 (repeat Info 1 and Info 0)

Hereinafter, a method of decoding by a receiving apparatus a signal transmitted by applying a symbol repetition technique to the transmitting apparatus will be described.

The transmitted signal may correspond to a wakeup packet, and a method of decoding the wakeup packet can be largely divided into two types. The first is non-coherent detection and the second is coherent detection. In non-coherent detection, the phase relationship between the transmitter and receiver signals is not fixed. Thus, the receiver does not need to measure and adjust the phase of the received signal. In contrast, the coherent detection method requires that the phase of the signal between the transmitter and the receiver be aligned.

The receiver includes the low power wake-up receiver described above. The low power wake-up receiver may decode a packet (wake-up packet) transmitted using an OOK modulation scheme using an envelope detector to reduce power consumption.

The envelope detector measures and decodes the power or magnitude of the received signal. The receiver sets a threshold based on the power or magnitude measured by the envelope detector. When decoding the symbol to which the OOK is applied, it is determined as information 1 if it is greater than or equal to the threshold value, and as information 0 when it is smaller than the threshold value.

The method of decoding a symbol to which the symbol repetition technique is applied is as follows. In the option 1, the receiving apparatus may use the wake-up preamble 722 to calculate a power when symbol 1 (symbol including information 1) is transmitted and determine the threshold.

In detail, the average power of the two symbols may be determined to determine information 1 (1 1) if the value is equal to or greater than the threshold value, and may be determined to be information 0 (0 0) below the threshold value.

In addition, in option 2, information may be determined by comparing the power of two symbols without determining a threshold.

Specifically, if information 1 is composed of 0 1 and information 0 is composed of 1 0, it is determined as information 0 if the power of the first symbol is greater than the power of the second symbol. On the contrary, if the power of the first symbol is less than the power of the second symbol, it is determined as information 1.

This is because the order of symbols can be reconstructed by an interleaver. The interleaver may be applied in units of specific symbol numbers below the packet unit.

In addition, not only two symbols but also n can be extended as follows. 11 illustrates various examples of a symbol repetition technique of repeating n symbols according to the present embodiment.

Option 1: Information 0 and information 1 may be repeatedly represented by the same symbol n times as shown in FIG.

-Information 0-> 0 0 ... 0 (repeat info 0 n times)

-Information 1-> 1 1 ... 1 (repeat information 1 n times)

* Option 2: As shown in FIG. 11, information 0 and information 1 may be repeatedly represented by different symbols n times.

-Information 0-> 0 1 0 1 ... or 1 0 1 0 ... (repeat info 0 and info 1 n times with each other)

-Info 1-> 1 0 1 0 ... or 0 1 0 1 ... (repeat info 1 and info 0 n times with each other)

Option 3: As shown in FIG. 11, one half of a symbol may be configured as information 0 and the other half may be configured as information 1 to represent n symbols.

-Information 0-> 0 0 ... 1 1 ... or 1 1 ... 0 0 ... (n / 2 symbols consist of information 0, the remaining n / 2 symbols consist of information 1 do)

-Information 1-> 1 1 ... 0 0 ... or 0 0 ... 1 1 ... (n / 2 symbols consist of information 0, the remaining n / 2 symbols consist of information 1 do)

Option 4: When n is odd, as shown in FIG. 11, the total number of symbols may be represented by dividing the number of symbols 1 (symbol including information 1) and the number of symbols 0 (symbol including information 0).

Information 0-> n symbols where the number of symbols 1 is odd and the number of symbols 0 is even, or n symbols where the number of symbols 1 is even and the number of symbols 0 is odd

Information 1-> n symbols where the number of symbols 0 is odd and the number of symbols 1 is even, or n symbols where the number of symbols 0 is even and the number of symbols 1 is odd

In addition, the order of symbols may be reconstructed by the interleaver. The interleaver may be applied in units of packets and specific symbols.

In addition, as described above, the receiving apparatus may determine whether the information is 0 or 1 by determining the threshold value and comparing the powers of the n symbols.

However, the use of consecutive symbol 0 (or off symbol) may cause a coexistence problem with an existing Wi-Fi device and / or another device. The coexistence problem is a problem caused by transmitting a signal by determining that another device is a channel idle state due to a continuous off symbol. Thus, the option 2 scheme may be preferred as it is desirable to avoid the use of consecutive off symbols to solve the leveling problem.

In addition, it can be extended in a manner of expressing m information using n symbols. In this case, the first or last m is represented by 0 (OFF) or 1 (ON) symbols depending on the information, and the nm or 0 (OFF) or 1 (ON) redundant symbols are formed consecutively before or after. can do.

For example, if a code rate of 3/4 is applied to the information 010, it may be 1,010 or 010,1 or 0,010 or 010,0. However, in order to prevent the use of consecutive off symbols, it may be desirable to apply a code rate of 1/2 or less.

In this embodiment as well, the order of symbols can be reconstructed by the interleaver. The interleaver may be applied in units of packets and specific symbols.

Hereinafter, various embodiments of a symbol to which the symbol repetition technique is applied will be described.

In general, a symbol to which the symbol repetition technique is applied may be represented by n (CP + 3.2us) or CP + n (1.6us).

As shown in FIG. 11, n (n> = 2) information signals (symbols) are used to represent 1 bit, and a specific sequence is applied to all available subcarriers (for example, 13). Form a signal (symbol).

Different sequences may be applied to the available subcarriers according to the 3.2us on signal and the 3.2us off signal. A 3.2us off signal can be generated by applying all coefficients to zero.

CP may be used by adopting a specific length from the rear of the information signal 3.2us immediately behind. At this time, CP may be 0.4us or 0.8us. This length is equal to the guard interval of 802.11ac.

Accordingly, 1 bit information corresponding to a symbol to which a general symbol repetition technique is applied may be represented as shown in the following table.

Information ‘0’	Information ‘1’
3.2us OFF-signal	3.2us ON-signal
Or two specific consecutive signals are 3.2us ON-signal + 3.2us OFF-signal, all other signals are ON or all OFF	Or two specific consecutive signals are 3.2us OFF-signal + 3.2us ON-signal, all other signals are ON or all OFF
Or two specific consecutive signals are 3.2us OFF-signal + 3.2us ON-signal, all other signals are ON or all OFF	Or two specific consecutive signals are 3.2us ON-signal + 3.2us OFF-signal, all other signals are ON or all OFF
Or a certain number (or ceil (n / 2) or floor (n / 2)) placed in a specific position is 3.2us OFF-signal, 3.2us ON-signalEx) ON + OFF + ON + OFF…	Or a certain number (or ceil (n / 2) or floor (n / 2)) placed in a specific position is 3.2us ON-signal, 3.2us OFF-signalEx) OFF + ON + OFF + ON + OFF…

Table 4 does not indicate CP separately. In fact, n pieces (CP + 3.2us) including CPs or CP + n pieces (3.2us) may indicate one 1-bit information. That is, in the case of n (CP + 3.2us), the 3.2us on signal may be viewed as a (CP + 3.2us) on signal, and the 3.2us off signal may be viewed as a (CP + 3.2us) off signal.

As another example, a symbol to which the symbol repetition technique is applied may be represented as CP + 3.2us + CP + 3.2us or CP + 3.2us + 3.2us.

According to the above embodiment, two information signals (symbols) are used to represent one bit and a specific sequence is applied to all available subcarriers (for example, thirteen), and then IFFT is taken to generate an information signal (symbol) of 3.2us. Form.

Different sequences may be applied to the available subcarriers according to the 3.2us on signal and the 3.2us off signal. A 3.2us off signal can be generated by applying all coefficients to zero.

CP may be used by adopting a specific length from the rear of the information signal 3.2us immediately behind. At this time, CP may be 0.4us or 0.8us. This length is equal to the guard interval of 802.11ac.

Accordingly, one bit information corresponding to a symbol to which the symbol repetition technique is applied may be represented as shown in the following table.

Information ‘0’	Information ‘1’
3.2us OFF-signal	3.2us ON-signal + 3.2us ON-signal
Or 3.2us ON-signal + 3.2us OFF-signal	Or 3.2us OFF-signal + 3.2us ON-signal
Or 3.2us OFF-signal + 3.2us ON-signal	Or 3.2us ON-signal + 3.2us OFF-signal

Table 5 does not indicate CP separately. Indeed, CP + 3.2us + CP + 3.2us or CP + 3.2us + 3.2us, including CP, may point to one 1-bit information. That is, in the case of CP + 3.2us + CP + 3.2us, the 3.2us on signal can be viewed as a (CP + 3.2us) on signal, and the 3.2us off signal can be viewed as a (CP + 3.2us) off signal. .

As another example, a symbol to which the symbol repetition technique is applied may be represented as CP + 3.2us + CP + 3.2us + CP + 3.2us or CP + 3.2us + 3.2us + 3.2us.

According to the above embodiment, three information signals (symbols) are used to represent one bit and a specific sequence is applied to all available subcarriers (eg, thirteen), and then IFFT is taken to generate an information signal (symbol) of 3.2us. Form.

Different sequences may be applied to the available subcarriers according to the 3.2us on signal and the 3.2us off signal. A 3.2us off signal can be generated by applying all coefficients to zero.

CP may be used by adopting a specific length from the rear of the information signal 3.2us immediately behind. At this time, CP may be 0.4us or 0.8us. This length is equal to the guard interval of 802.11ac.

Accordingly, one bit information corresponding to a symbol to which the symbol repetition technique is applied may be represented as shown in the following table.

Information ‘0’	Information ‘1’
3.2us OFF-signal + 3.2us OFF-signal + 3.2us OFF-signal	3.2us ON-signal + 3.2us ON-signal + 3.2us ON-signal
Or 3.2us ON-signal + 3.2us ON-signal + 3.2us OFF-signal	Or 3.2us ON-signal + 3.2us OFF-signal + 3.2us ON-signal
Or 3.2us ON-signal + 3.2us OFF-signal + 3.2us ON-signal	Or 3.2us ON-signal + 3.2us ON-signal + 3.2us OFF-signal
Or 3.2us ON-signal + 3.2us OFF-signal + 3.2us ON-signal	Or 3.2us OFF-signal + 3.2us ON-signal + 3.2us OFF-signal

Table 6 does not indicate CP separately. In fact, CP + 3.2us + CP + 3.2us + CP + 3.2us or CP + 3.2us + 3.2us + 3.2us, including CP, may point to one 1-bit information. That is, in the case of CP + 3.2us + CP + 3.2us + CP + 3.2us, the 3.2us on signal can be viewed as a (CP + 3.2us) on signal, and the 3.2us off signal is a (CP + 3.2us) off It can be seen as a signal.

As another example, a symbol to which the symbol repetition technique is applied may be represented as CP + 3.2us + CP + 3.2us + CP + 3.2us + CP + 3.2us or CP + 3.2us + 3.2us + 3.2us + 3.2us.

According to the above embodiment, four information signals (symbols) are used to represent one bit and a specific sequence is applied to all available subcarriers (for example, thirteen), and then IFFT is taken to generate an information signal (symbol) of 3.2us. Form.

Different sequences may be applied to the available subcarriers according to the 3.2us on signal and the 3.2us off signal. A 3.2us off signal can be generated by applying all coefficients to zero.

CP may be used by adopting a specific length from the rear of the information signal 3.2us immediately behind. At this time, CP may be 0.4us or 0.8us. This length is equal to the guard interval of 802.11ac.

Accordingly, one bit information corresponding to a symbol to which the symbol repetition technique is applied may be represented as shown in the following table.

Information ‘0’	Information ‘1’
3.2us OFF-signal + 3.2us OFF-signal + 3.2us OFF-signal + 3.2us OFF-signal	3.2us ON-signal + 3.2us ON-signal + 3.2us ON-signal + 3.2us ON-signal
Or 3.2us ON-signal + 3.2us ON-signal + 3.2us ON-signal + 3.2us OFF-signal	Or 3.2us ON-signal + 3.2us ON-signal + 3.2us OFF-signal + 3.2us ON-signal
Or 3.2us ON-signal + 3.2us ON-signal + 3.2us OFF-signal + 3.2us ON-signal	Or 3.2us ON-signal + 3.2us ON-signal + 3.2us ON-signal + 3.2us OFF-signal
Or 3.2us ON-signal + 3.2us ON-signal + 3.2us OFF-signal + 3.2us ON-signal	Or 3.2us ON-signal + 3.2us OFF-signal + 3.2us ON-signal + 3.2us ON-signal
Or 3.2us ON-signal + 3.2us OFF-signal + 3.2us ON-signal + 3.2us ON-signal	Or 3.2us ON-signal + 3.2us ON-signal + 3.2us OFF-signal + 3.2us ON-signal
Or 3.2us ON-signal + 3.2us OFF-signal + 3.2us ON-signal + 3.2us OFF-signal	Or 3.2us OFF-signal + 3.2us ON-signal + 3.2us OFF-signal + 3.2us ON-signal
Or 3.2us ON-signal + 3.2us ON-signal + 3.2us OFF-signal + 3.2us OFF-signal	Or 3.2us OFF-signal + 3.2us OFF-signal + 3.2us ON-signal + 3.2us ON-signal
Or 3.2us OFF-signal + 3.2us OFF-signal + 3.2us ON-signal + 3.2us ON-signal	Or 3.2us ON-signal + 3.2us ON-signal + 3.2us OFF-signal + 3.2us OFF-signal

Table 7 does not indicate CP separately. Indeed, CP + 3.2us + CP + 3.2us + CP + 3.2us + CP + 3.2us or CP + 3.2us + 3.2us + 3.2us + 3.2us, including CP, may point to one single bit of information. That is, in the case of CP + 3.2us + CP + 3.2us + CP + 3.2us + CP + 3.2us, the 3.2us on signal can be regarded as (CP + 3.2us) on signal and the 3.2us off signal is (CP + 3.2us) off signal.

As another example, a symbol to which Manchester coding is applied based on symbol repetition may be represented by n (CP + 1.6us + CP + 1.6us) or CP + n (1.6us + 1.6us).

According to the above embodiment, a symbol is repeated using a symbol repeated n (> = 2) times, and a specific sequence is applied to all available subcarriers (for example, 13), and the remaining coefficients of 0 are applied. By setting IFFT, 3.2us of signal with 1.6us period is generated. Take one of these and set it as a 1.6us information signal (symbol).

The sub information may be called a 1.6us information signal. The 1.6us information signal may be a 1.6us on signal or a 1.6 off signal. The 1.6us on signal and the 1.6 off signal may have different sequences applied to each subcarrier. The 1.6us off signal can be generated by applying all coefficients to zero.

CP can be used by adopting a specific length from the back of the 1.6us of the information signal immediately after. At this time, CP may be 0.4us or 0.8us. This length is equal to the guard interval of 802.11ac.

Accordingly, 1 bit information corresponding to a symbol to which Manchester coding is applied based on the symbol repetition may be represented as shown in the following table.

Information ‘0’	Information ‘1’
(1.6us ON-signal + 1.6us OFF-signal) Repeat n times	(1.6us OFF-signal + 1.6us ON-signal) Repeat n times
Or (1.6us OFF-signal + 1.6us ON-signal) n times	Or (1.6us ON-signal + 1.6us OFF-signal) n times
(1.6us ON-signal + 1.6us OFF-signal) + (1.6us OFF-signal + 1.6us ON-signal) floor (n / 2) Repeat + if necessary (1.6us ON-signal + 1.6us OFF-signal)	(1.6us OFF-signal + 1.6us ON-signal) + (1.6us ON-signal + 1.6us OFF-signal) floor (n / 2) Repeat + if necessary (1.6us OFF-signal + 1.6us ON-signal)
(1.6us OFF-signal + 1.6us ON-signal) + (1.6us ON-signal + 1.6us OFF-signal) floor (n / 2) Repeat + if necessary (1.6us OFF-signal + 1.6us ON-signal)	(1.6us ON-signal + 1.6us OFF-signal) + (1.6us OFF-signal + 1.6us ON-signal) floor (n / 2) Repeat + if necessary (1.6us ON-signal + 1.6us OFF-signal)

Table 8 does not indicate CP separately. In fact, n (CP + 1.6us + CP + 1.6us) or CP + n (1.6us + 1.6us) including CP may indicate one 1-bit information. That is, in the case of n (CP + 1.6us + CP + 1.6us), the 1.6us on signal can be viewed as a (CP + 1.6us) on signal, and the 1.6us off signal is a (CP + 1.6us) off signal. Can be seen as.

Like the embodiments described above, the symbol repetition technique can satisfy the range requirement of low power wake-up communication. When only the OOK method is applied, the data rate for one symbol is 250 Kbps (4us). In this case, if the symbol is repeated twice using the symbol repetition technique, the data rate may be 125 Kbps (8us), the fourth time, the data rate is 62.5Kbps (16us), and the eighth time the data rate is 31.25Kbps (32us). have. In the case of low-power wake-up communication, if there is no BCC, the symbol needs to be repeated eight times to satisfy the range requirement.

Hereinafter, various embodiments of a symbol to which a symbol reduction technique is applied among symbol types that can be used in the WUR will be described.

12 illustrates various examples of a symbol reduction technique according to the present embodiment.

According to the embodiment of FIG. 12, as the m value increases, the symbol is further reduced to reduce the length of a symbol carrying one piece of information. When m = 2, the length of a symbol carrying one piece of information becomes CP + 1.6us. When m = 4, the length of a symbol carrying one piece of information becomes CP + 0.8us. When m = 8, the length of a symbol carrying one piece of information becomes CP + 0.4us.

As the length of the symbol decreases, a high data rate can be ensured. If only the OOK scheme is applied, the data rate for one symbol is 250 Kbps (4us). In this case, using m = 2, the data rate is 500 Kbps (2us), if m = 4, the data rate is 1Mbps (1us), if m = 8 data rate can be 2Mbps (0.5us). .

For example, a symbol to which a symbol reduction technique is generally applied may be represented by CP + 3.2us / m (m = 2,4,8,16,32, ...) (option 1).

As shown in option 1 of FIG. 12, a symbol using a symbol reduction technique is used to represent one bit, and a specific sequence is applied to every available subcarrier (for example, 13) in m units, and the remaining coefficients are set to zero. do. Subsequently, if IFFT is applied to the subcarrier to which the specific sequence is applied, a 3.2us signal having a 3.2us / m period is generated. Take one of these and map it to the 3.2us / m information signal (information 1).

For example, if a specific sequence is applied in units of two columns (m = 2) to 13 subcarriers, the on signal may be configured as follows.

On signal (information 1): {a 0 b 0 c 0 d 0 e 0 f 0 g} or {0 a 0 b 0 c 0 d 0 e 0 f 0}, where a, b, c, d, e, f, g is 1 or -1.

As another example, if a specific sequence is applied to 13 subcarriers in units of four squares (m = 4), the on signal may be configured as follows.

On signal (Info 1): {a 0 0 0 b 0 0 0 c 0 0 0 d} or {0 a 0 0 0 b 0 0 0 c 0 0 0} or {0 0 a 0 0 0 b 0 0 0 c 0 0} or {0 0 0 a 0 0 0 b 0 0 0 c 0} or {0 0 a 0 0 0 0 0 0 0 b 0 0}, where a, b, c, d is 1 or -1.

As another example, if a specific sequence is applied to 13 subcarriers by 8 columns (m = 8), the on signal may be configured as follows.

On signal (information 1): {a 0 0 0 0 0 0 0 b 0 0 0 0} or {0 a 0 0 0 0 0 0 0 b 0 0 0} or {0 0 a 0 0 0 0 0 0 0 0 b 0 0} or {0 0 0 a 0 0 0 0 0 0 0 b 0}, or {0 0 0 0 a 0 0 0 0 0 0 0 b}, where a and b are 1 or -1 .

The 3.2us / m information signal is divided into a 3.2us / m on signal and a 3.2us / m off signal. In addition, different sequences may be applied to the (usable) subcarriers for the 3.2us / m on signal and the 3.2us / m off signal, respectively. A 3.2us / m off signal can be generated by applying all coefficients to zero.

CP can be used by adopting a specific length from the back of the information signal 3.2us / m immediately behind. At this time, CP may be 0.4us or 0.8us. This length is equal to the guard interval of 802.11ac. However, when m = 8, the CP cannot be 0.8us. Alternatively, CP may be 0.1us or 0.2us, or another value.

Accordingly, 1 bit information corresponding to a symbol to which a general symbol reduction technique is applied may be represented as shown in the following table.

Information ‘0’	Information ‘1’
3.2us / m OFF-signal	3.2us / m ON-signal

CP is not shown separately in Table 9. In fact, CP + 3.2us / m including CP may indicate one 1-bit information. That is, the 3.2us / m on signal may be viewed as a CP + 3.2us / m on signal, and the 3.2us / m off signal may be viewed as a CP + 3.2us / m off signal.

As another example, a symbol to which the symbol reduction technique is applied may be represented by CP + 3.2us / m + CP + 3.2us / m (m = 2,4,8) (option 2).

In the OOK transmission using the Wi-Fi transmitter, the time used for transmitting one bit (or symbol) except for the guard interval of the transmission signal is 3.2 us. At this time, if the symbol reduction technique is applied, the time used for one bit transmission is 3.2us / m. However, in this embodiment, the time used for transmitting one bit is repeated as 3.2us / m + 3.2us / m by repeating a symbol to which the symbol reduction technique is applied, and the signal between 3.2us / m signals is also used by using the characteristics of Manchester coding. A transition in size was allowed to occur. That is, each sub-information having a length of 3.2us / m should have a value of 0 or 1, and may configure a signal in the following manner.

* Information 0-> 1 0 (each can be referred to as sub information 1 0 or sub symbol 1 (ON) 0 (OFF))

First 3.2us / m signal (sub-information 1 or sub-symbol 1): A specific sequence in m-column for all available subcarriers (e.g. 13 subcarriers) to generate symbols with symbol reduction Apply. That is, in a particular sequence, coefficients may exist at intervals of m columns.

The transmitter maps a specific sequence to K consecutive subcarriers of 64 subcarriers and sets a coefficient to 0 for the remaining subcarriers to perform IFFT. In this way, signals in the time domain can be generated. Since the signal in the time domain has coefficients at intervals of m in the frequency domain, a 3.2us signal having a 3.2us / m period is generated. You can take one of these and use it as a 3.2us / m on signal (sub information 1).

Second 3.2us / m signal (sub information 0 or subsymbol 0): As with the first 3.2us / m signal, the transmitter maps a particular sequence to K consecutive subcarriers of 64 subcarriers, Can be generated to generate a time domain signal. The sub information 0 may correspond to a 3.2 us / m off signal. The 3.2us / m off signal can be generated by setting all coefficients to zero.

One of the first or second 3.2us / m periodic signals of the signal in the time domain may be selected and used as the sub information 0.

* Information 1-> 0 1 (each can be referred to as sub information '0', '1' or sub symbol 0 (OFF) 1 (ON))

-Since information 1 is also divided into the first 3.2us / m signal (sub information 0) and the second 3.2us / m signal (sub information 1), the signal corresponding to each sub information is generated in the same way as information 0 is generated. Can be configured.

In addition, information 0 may be configured as 01 and information 1 may be configured as 10.

As in option 2 of FIG. 12, 1-bit information corresponding to a symbol to which a symbol reduction technique is applied may be represented as shown in the following table.

Information ‘0’	Information ‘1’
3.2us / m OFF-signal + 3.2us / m ON-signal or 3.2us / m ON-signal + 3.2us / m OFF-signal	3.2us / m ON-signal + 3.2us / m OFF-signal or 3.2us / m OFF-signal + 3.2us / m ON-signal

In Table 10, CP is not separately indicated. In fact, CP + 3.2us / m including CP may point to one 1-bit information. That is, the 3.2us / m on signal may be viewed as a CP + 3.2us / m on signal, and the 3.2us / m off signal may be viewed as a CP + 3.2us / m off signal.

Embodiments illustrated by option 1 and option 2 of FIG. 12 may be generalized as shown in the following table.

	Information ‘0’	Information ‘1’
Option 1 (m = 2,4,8)	2us OFF-signal	2us ON-signal
	1us OFF-signal	1us ON-signal
	0.5us OFF-signal	0.5us ON-signal
Option 2 (m = 4,8)	1us OFF-signal + 1us ON-signal or 1us ON-signal + 1us OFF-signal	1us ON-signal + 1us OFF-signal or 1us OFF-signal + 1us ON-signal
	0.5us OFF-signal + 0.5us ON-signal or 0.5us ON-signal + 0.5us OFF-signal	0.5us ON-signal + 0.5us OFF-signal or 0.5us OFF-signal + 0.5us ON-signal

Table 11 shows each signal in length including CP. That is, CP + 3.2us / m including the CP may indicate one 1-bit information.

For example, when m = 4 in Option 2, a symbol carrying one piece of information becomes CP + 0.8us, and thus a 1us off signal or 1us on signal is composed of a CP (0.2us) + 0.8us signal. In Option 2, since Manchester coding is applied and symbols are repeated, the data rate of one information can be 500 Kbps when m = 4.

As another example, when m = 8 in Option 2, the length of a symbol carrying one piece of information becomes CP + 0.4us, so that the 0.5us off signal or the 0.5us on signal consists of a CP (0.1us) + 0.4us signal. In Option 2, since Manchester coding is applied and symbols are repeated, the data rate of one information may be 1Mbps when m = 8.

In the table below, the data rates that can be secured through the above-described embodiments are compared with each other.

CP	Default symbol (Example 1) (CP + 3.2us)	Man. Symbol (Example 2) (CP + 1.6 + CP + 1.6)	Man. Symbol (Example 3) (CP + 1.6 + 1.6)
0.4us	277.8	250.0	277.8
0.8us	250.0	208.3	250.0

CP	Symbol rep.n (CP + 3.2us)			CP rep.CP + n (3.2us)			Man. symbol rep.n (CP + 1.6us + CP + 1.6us)
	n = 2 (Example 4)	n = 3 (Example 5)	n = 4 (Example 6)	n = 2 (Example 7)	n = 3 (Example 8)	n = 4 (Example 9)	n = 2 (Example 10)	n = 3 (Example 11)	n = 4 (Example 12)
0.4us	138.9	92.6	69.4	147.1	100.0	75.8	125.0	83.3	62.5
0.8us	125.0	83.3	62.5	138.9	96.2	73.5	104.2	69.4	52.1

CP	Man. CP + n symbols (1.6us + 1.6us)			Symbol reductionCP + 3.2us / m
	n = 2 (Example 13)	n = 3 (Example 14)	n = 4 (Example 15)	m = 2 (Example 16)	m = 4 (Example 17)	m = 8 (Example 18)
0.4us	147.1	100.0	75.8	500.0	833.3	1250.0
0.8us	138.9	96.2	73.5	416.7	625.0	NA

CP	Symbol reductionCP + 3.2us / m		Man. symbol rep. w / Man.CP + 3.2us / m + CP + 3.2us / m
	m = 4	m = 8	m = 4	m = 8
0.1us	1111.1	2000	555.6	1000
0.2us	1000	1666.7	500	833.3

FIG. 13 shows an example of configuring a 2us on signal based on signal masking according to the present embodiment.

Data rates can be ensured according to the various symbol types that can be used in the WUR. In this case, a method for generating a 2us on signal may be proposed to secure a data rate of 250 Kbps. FIG. 13 proposes a masking based technique using a sequence of length 13 (all coefficients are inserted into 13 consecutive subcarriers in the 20 MHz band).

Referring to FIG. 13, in the case of a masking-based approach, first, a 4us OOK symbol may be generated. A 64-point IFFT is applied to 13 consecutive subcarriers of 20 MHz band to perform a 64-point IFFT, and a 4us OOK symbol is generated by adding 0.8us CP or GI. The 2us on signal may be configured by masking half of the 4us OOK symbol.

For example, referring to FIG. 13, the information 0 may take the first half of the 4us symbol to configure the 2us on signal. The latter half of the 4us symbol does not transmit any information and thus can constitute a 2us off signal. In addition, information 1 may take a half part of the symbol to form a 2us false signal. The front half of the 4us symbol can configure a 2us off signal by not transmitting any information.

In addition, in the following, various data rates may be applied to a payload of a WUR PPDU in an 802.11ba system, and two types of sync parts or sync fields having different lengths may be used to reduce the overhead of the WUR PPDU. WUR PPDU can be configured. In this specification, various schemes for indicating a data rate applied to a payload using two types of sink parts or sink fields are proposed.

In the present specification, when a WUR PPDU transmitting to wake up a primary radio transmits WUR signals to a plurality of STAs using wide bandwidth (or multi-channel), a sequence loaded on 13 subcarriers in terms of frequency is formed to reduce PAPR. We propose a method of transmission.

Specifically, when the WUR PPDU transmitted to wake up the primary radio is transmitted over wide bandwidth (eg 40 MHz, 80 MHz and 160 MHz), the WUR signal is transmitted using 4 MHz in 20 MHz and the WUR signal using 13 subcarriers in terms of frequency. To form. In case of transmitting the WUR signal using wide bandwidth, PAPR may be increased by repeatedly transmitting the same 13 subcarriers within the bandwidth. Therefore, the present specification proposes a method of configuring a frequency sequence carried on 13 subcarriers to reduce PAPR when transmitting MU WUR PPDU using wide bandwidth.

14 illustrates an example of a wakeup packet structure to which a sync part according to the present embodiment is applied.

14 is an example of a WUR PPDU to which a sync part (or sync field) is applied in an IEEE 802.11ba system.

The WRU signal for waking up the primary radio may be transmitted using a frame format as shown in FIG. 14.

As shown in FIG. 14, the WUR frame may be configured to transmit an L-Part first before the WUR part for coexistence with legacy. For example, the WUR part may include a WUR-sync field and a WUR-payload field as described above, and the WUR-payload includes control information rather than data for a device.

In this case, the L-PART is used for the third party device, not the WUR receiver, and the WUR receiver may not decode the L-part.

As shown in FIG. 14, the preamble of the WUR is composed of a non WUR portion and a WUR sync field, and can indicate data rate information used for payload using the WUR sync field. The length of the WUR sync field is as follows according to the data rate. .

WUR sync field length at high data rate (250Kbps) = 64us

WUR sync field length at low data rate (62.5 Kbps) = 128 us

Accordingly, the WUR-payload may also vary depending on the frame body size.

The WUR PPDU may be transmitted using wide bandwidth differently from FIG. 14, and the WUR PPDU transmitted using the wide bandwidth (e.g. 40 MHz / 80 MHz / 160 MHz) is transmitted as shown in FIGS. 15 to 17. The transmission of the WUR PPDU over the wide bandwidth indicates that the WUR PPDU is transmitted with WUR Frequency Division Multiplexing Access (FDMA) applied.

15 shows an example of a wakeup packet structure transmitted through the 40 MHz band according to the present embodiment.

16 illustrates an example of a wakeup packet structure transmitted through an 80 MHz band according to the present embodiment.

17 shows an example of a wakeup packet structure transmitted through the 160MHz band according to the present embodiment.

As shown in FIGS. 15 to 17, in case of transmitting the WUR PPDU using wide bandwidth, the legacy preamble and the BPSK mark, which are non WUR portions, are duplexed and transmitted in units of 20 MHz. In addition, the WUR portion, the WUR sync field and the WUR payload are transmitted using a 4 MHz bandwidth (13 tone or subcarriers) centered on a center frequency within a 20 MHz channel.

In this specification, a problem that may occur in a wake-up radio (WUR) environment in which frequency division multiple access (FDMA) is applied, and a method for solving the problem are proposed.

18 shows an example of a WUR frame format according to the present embodiment.

Standardization is underway for a technology that uses primary radios to wake primary connectivity radio (PCR). This reduces the power consumption of the WiFi station has attracted much attention in the standardization work. This wake-up radio (WUR) operates on the 802.11 family, an existing WiFi standard. The AP may use the structure shown in FIG. 18 to transmit a WUR frame.

As the days go by, the number of wireless terminals supporting WiFi is growing exponentially. Downlink Multi-user MIMO was supported in 802.11ac, and the latest WiFi standard 802.11ax supports Uplink MU-MIMO as well as Downlink to deal with a large number of terminals. Accordingly, the wakeup radio is also actively discussed about the frame structure and operation process to wake up a plurality of terminals at once.

One of the proposed methods for waking up multiple terminals is WUR FDMA transmission, which extends the WUR channel by using FDMA up to 40, 80, and 160 MHz used in PCR as well as 20 MHz. The WUR FDMA transmission may use a structure as shown in FIGS. 15 to 17.

19 shows an example of collision occurring in the primary channel according to the present embodiment.

By utilizing the WUR FDMA transmission, the time required to wake up a plurality of STAs can be greatly reduced. However, various problems may occur when there is no STA to wake up in a corresponding sub-channel. In particular, when there is no STA to be woken in the primary channel as in the case of FIG. 19, collision from an inter / intra STA may occur, which causes a problem in that overall network throughput decreases.

20 illustrates an example of suspending transmission of a wake-up frame in the secondary channel until transmission of the wake-up frame in the primary channel according to the present embodiment.

If the STA to be woken through the WUR does not exist in the primary channel, the AP may also consider a method of delaying transmission to the secondary channel until the WUR frame is sent to the primary channel. In this case, the above-mentioned problems do not occur at the source, but a fairness problem may occur between the STAs existing in the primary channel and the STAs existing in the remaining secondary channel. In some cases, as shown in FIG. It takes a long time to wake up.

1. offered Example

1-1. WUR  Null frame without FCS

If the STA to be woken through the WUR does not exist in the primary channel, the AP may fill and send a predefined WUR null frame. In this case, the STA occupies the primary channel so that other STAs do not attempt transmission, and after transmission of the AP is completed, channel access is attempted after channel idle. When defining a WUR null frame without including the FCS, it may be considered to send the LDR for reliability of the WUR null frame.

1) WUR Null frame format

21 shows an example of a WUR null frame format excluding FCS according to the present embodiment.

A WUR null frame may be defined using a type subfield in a frame control field. STAs receiving a WUR frame defined as a WUR null frame do not wake-up until the length of the length is decoded to the frame control field. The Length field is defined as the length of the padding symbol to be included later. 21 illustrates a format of a WUR null frame.

2) Motion Effects and Pros and Cons

22 shows an example of using a WUR null frame according to the present embodiment.

The STA present in the primary receives the WUR frame and sleeps for the length of time defined in the Length if it is determined that the frame is the WUR null frame through the Type subfield. In addition, if the inter- / intra-STA present in the channel listens to the channel before transmitting the PCR frame, it can know that it is busy through energy detection and defer transmission. 22 illustrates an example of utilizing a WUR Null frame without FCS.

If you do not transmit the FCS, there is an advantage to save as much power, but if the transmission to the LDR for reliability, the power can be wasted that can be selected according to the channel conditions and different WUR frame length. Since the length of the WDR sync and the frame control field of the LDR is long (128us and 128us, respectively), when all other WUR frames are HDR, the primary channel may be occupied for a longer time, and thus overall channel efficiency may be deteriorated.

1-2. WUR  Null frame with FCS

If the STA to be woken through the WUR does not exist in the primary channel, the AP may fill and send a predefined WUR null frame. In this case, the STA occupies the primary channel so that other STAs do not attempt transmission, and after transmission of the AP is completed, channel access is attempted after channel idle. This WUR Null frame with FCS includes an FCS field in a WUR Null frame.

1) WUR Null frame format

23 shows an example of a WUR null frame format including an FCS according to the present embodiment.

A WUR null frame may be defined using a type subfield in a frame control field. STAs receiving a WUR frame defined as a WUR null frame decode to the FCS field and then wake-up until the length of the length included in the FC field. not up The Length field is defined as the length of the padding symbol to be included later. In case of HDR transmission, reliability may be lower than LDR transmission. Therefore, connect FCS after frame control. FCS may be selectively applied only for HDR transmission, or may be used for both HDR / LDR. 23 illustrates a format of a WUR null frame.

2) Motion Effects and Pros and Cons

24 shows another example utilizing the WUR null frame according to the present embodiment.

The STA present in the primary receives the WUR frame and sleeps for the length of time defined in the Length if it is determined that the frame is the WUR null frame through the Type subfield. In addition, if the inter- / intra-STA present in the channel listens to the channel before transmitting the PCR frame, it can know that it is busy through energy detection and defer transmission. An example of using LDR and HDR WUR null frame padding is illustrated in FIG. 24.

In the case of including the FCS, the reliability of the preceding Frame Control field is increased, which greatly reduces the packer error rate of received STAs. In addition, the transmission in HDR has the advantage that other wake-up frames can respond accordingly, whether LDR or HDR.

1-3. PCR  How to fill a frame

25 shows an example of transmitting a PCR PPDU simultaneously with a WUR frame according to the present embodiment.

If the STA to be woken up through the WUR does not exist in the primary channel, the PCR frame in the Tx buffer is transmitted to prevent the primary channel interruption problem. In this case, the STA occupies the primary channel so that other STAs do not attempt transmission, and after transmission of the AP is completed, channel access is attempted after channel idle. Therefore, there is no reduction in overall network throughput and an empty channel can be used for PCR transmission. 25 shows an example of the method. Although the format of the PCR PPDU is not limited, the time at which the transmission of the PCR PPDU is terminated should be at least longer than the length of another WUR frame.

26 is a flowchart illustrating a procedure of transmitting a wake-up packet by applying the OOK method according to the present embodiment.

An example of FIG. 26 is performed in a transmitter, the receiver may correspond to a low power wake-up receiver, and the transmitter may correspond to an AP. This embodiment describes a case in which a wake-up packet transmitted to wake up a primary radio is transmitted to a plurality of receivers through a wide bandwidth or multi-channel.

The transmission of the WUR PPDU over a wide bandwidth means that the WUR PPDU per 20 MHz band within a wide bandwidth is transmitted by applying a frequency division multiplexing access (FDMA) scheme. Therefore, this embodiment can be said that WUR FDMA is applied.

In addition, the present embodiment assumes that a broadband is a band for an 80 MHz channel, and if there is no STA to wake up through a WUR on the primary channel among the 80 MHz channels or there is no pending wakeup packet to transmit, A new definition proposes a method of preventing a collision due to channel access of a third party STA.

First of all, the term “on signal” may correspond to a signal having an actual power value. The off signal may correspond to a signal that does not have an actual power value.

In operation S2610, the transmitter generates a wakeup packet by applying an on-off keying (OOK) scheme.

In step S2620, the transmitter transmits the wake-up packet to the receiver through the 80MHz channel.

How the wakeup packet is configured in the present embodiment is as follows.

The 80 MHz channel includes first to fourth subchannels.

The wakeup packet includes a first PHY protocol data unit (PPDU) transmitted on the first subchannel.

If there is no wakeup packet for the receiver in the first subchannel (if there is no receiver to wake up through the wakeup packet in the first subchannel), the first PPDU is a wakeup null. Frame includes a wake-up null frame and a padding symbol. That is, even if there is no pending wakeup packet in the first subchannel, the state of the first subchannel may be made busy by transmitting the wakeup null frame and the padding symbol. As a result, a third party STA (inter STA or intra STA) may determine that the first subchannel is busy until the wakeup null frame and the padding symbol length, and suspend data transmission.

The wakeup null frame and the padding symbol are transmitted in a first frequency band associated with 13 consecutive subcarriers in the first subchannel. The first frequency band may be a 4 MHz band.

The first subchannel is a primary channel of the 80 MHz channel.

The wake-up null frame may include a frame control field and a FCS field. However, the wakeup null frame may not include an address field, a type dependent control field, and a frame body field.

The frame control field may include a type subfield and a length subfield.

The type subfield may include information that the type of the first PPDU is the wakeup null frame.

The length subfield may include information about the length of the first PPDU.

As a result, the receiving device receiving the wake-up null frame may decode the frame control field and the FCS field. In addition, the receiving apparatus receiving the wake-up null frame detects the type subfield to know that the received frame is the wake-up null frame, and detects the length subfield to pad the padding symbol to a certain point. I can see that.

The wakeup packet may further include a second PPDU transmitted in the second subchannel, a third PPDU transmitted in the third subchannel, and a fourth PPDU transmitted in a fourth subchannel.

The padding symbol may be padded such that the length of the first PPDU is equal to the maximum length of the lengths of the second to fourth PPDUs.

When there is a wakeup signal for the receiver in the second subchannel, the second PPDU may include a first wakeup frame. The first wakeup frame may be generated by inserting a first sequence into 13 consecutive subcarriers in the second subchannel and performing an inverse fast fourier transform (IFFT).

When the wakeup signal for the receiver is present in the third subchannel, the third PPDU may include a second wakeup frame. The second wakeup frame may be generated by inserting a second sequence into 13 consecutive subcarriers in the third subchannel and performing IFFT.

When the wakeup signal for the receiver is present in the fourth subchannel, the fourth PPDU may include a third wakeup frame. The third wakeup frame may be generated by inserting a third sequence into 13 consecutive subcarriers in the fourth subchannel and performing IFFT.

The receiving device may include first to fourth STAs. The first STA may not support a wake-up receiver (WUR). That is, the first STA is not an STA to be woken through the WUR. The second to fourth STAs support WUR. That is, the second to fourth STAs are STAs that wake up through the WUR.

The first PPDU may be transmitted in the first subchannel for the first STA. The second PPDU may be transmitted in the second subchannel for the second STA. The third PPDU may be transmitted in the third subchannel for the third STA. The fourth PPDU may be transmitted in the fourth subchannel for the fourth STA.

The first STA receives the first PPDU in the first subchannel, and determines that the first PPDU is the wakeup null frame through the type subfield. The first STA sleeps by the length of the first PPDU through the length subfield. Accordingly, the first STA may determine that the first subchannel is busy while the first PPDU is transmitted and suspend data transmission and reception. After the first PPDU is transmitted, the first STA may perform channel access to the first subchannel to perform data transmission and reception.

Each of the first to fourth subchannels may be a 20 MHz channel.

The wakeup null frame may have a first data rate or second data. The first data rate may be 62.5 kb / s, and the second data rate may be 250 kb / s.

Channel access for each subchannel is described as follows.

Channel access for the first to fourth subchannels may be performed during a Point Coordination Function (PCF) Interframe Space (PIFS) section immediately before the transmission opportunity (TXOP) starts. The wakeup packet may be transmitted during the TXOP.

Further, when the first to fourth subchannels are idle as a result of performing the channel access, the transmitter may determine whether the pending wakeup packet is present in the first to fourth subchannels.

The first to third sequences may be set to 13 length sequences, 7 length sequences, or the like based on the data rate. The IFFT may be a 64 point IFFT.

In addition, the transmitter may first configure power values of the on signal and the off signal, and configure the on signal and the off signal. The receiver decodes the on signal and the off signal using an envelope detector, thereby reducing power consumed in decoding.

27 is a flowchart illustrating a procedure of receiving a wake-up packet by applying the OK method according to the present embodiment.

An example of FIG. 27 is performed in a receiving apparatus, the receiving apparatus may correspond to a low power wake-up receiver, and the transmitting apparatus may correspond to an AP. This embodiment describes a case in which a wake-up packet transmitted to wake up a primary radio is transmitted to a plurality of receivers through a wide bandwidth or multi-channel.

The transmission of the WUR PPDU over a wide bandwidth means that the WUR PPDU per 20 MHz band within a wide bandwidth is transmitted by applying a frequency division multiplexing access (FDMA) scheme. Therefore, this embodiment can be said that WUR FDMA is applied.

In addition, the present embodiment assumes that a broadband is a band for an 80 MHz channel, and if there is no STA to wake up through a WUR on the primary channel among the 80 MHz channels or there is no pending wakeup packet to transmit, A new definition proposes a method of preventing a collision due to channel access of a third party STA.

First of all, the term “on signal” may correspond to a signal having an actual power value. The off signal may correspond to a signal that does not have an actual power value.

In step S2710, the receiving device receives a wake-up packet generated by applying the On-Off Keying (OOK) method from the transmitting device through the 80MHz channel.

In operation S2720, the receiver decodes the wakeup packet for a channel supported by the receiver.

How the wakeup packet is configured in the present embodiment is as follows.

The 80 MHz channel includes first to fourth subchannels.

The wakeup packet includes a first PHY protocol data unit (PPDU) transmitted on the first subchannel.

If there is no wakeup packet for the receiver in the first subchannel (if there is no receiver to wake up through the wakeup packet in the first subchannel), the first PPDU is a wakeup null. Frame includes a wake-up null frame and a padding symbol. That is, even if there is no pending wakeup packet in the first subchannel, the state of the first subchannel may be made busy by transmitting the wakeup null frame and the padding symbol. As a result, a third party STA (inter STA or intra STA) may determine that the first subchannel is busy until the wakeup null frame and the padding symbol length, and suspend data transmission.

The wakeup null frame and the padding symbol are transmitted in a first frequency band associated with 13 consecutive subcarriers in the first subchannel. The first frequency band may be a 4 MHz band.

The first subchannel is a primary channel of the 80 MHz channel.

The wake-up null frame may include a frame control field and a FCS field. However, the wakeup null frame may not include an address field, a type dependent control field, and a frame body field.

The frame control field may include a type subfield and a length subfield.

The type subfield may include information that the type of the first PPDU is the wakeup null frame.

The length subfield may include information about the length of the first PPDU.

As a result, the receiving device receiving the wake-up null frame may decode the frame control field and the FCS field. In addition, the receiving apparatus receiving the wake-up null frame detects the type subfield to know that the received frame is the wake-up null frame, and detects the length subfield to pad the padding symbol to a certain point. I can see that.

The wakeup packet may further include a second PPDU transmitted in the second subchannel, a third PPDU transmitted in the third subchannel, and a fourth PPDU transmitted in a fourth subchannel.

The padding symbol may be padded such that the length of the first PPDU is equal to the maximum length of the lengths of the second to fourth PPDUs.

When there is a wakeup signal for the receiver in the second subchannel, the second PPDU may include a first wakeup frame. The first wakeup frame may be generated by inserting a first sequence into 13 consecutive subcarriers in the second subchannel and performing an inverse fast fourier transform (IFFT).

When the wakeup signal for the receiver is present in the third subchannel, the third PPDU may include a second wakeup frame. The second wakeup frame may be generated by inserting a second sequence into 13 consecutive subcarriers in the third subchannel and performing IFFT.

When the wakeup signal for the receiver is present in the fourth subchannel, the fourth PPDU may include a third wakeup frame. The third wakeup frame may be generated by inserting a third sequence into 13 consecutive subcarriers in the fourth subchannel and performing IFFT.

The receiving device may include first to fourth STAs. The first STA may not support a wake-up receiver (WUR). That is, the first STA is not an STA to be woken through the WUR. The second to fourth STAs support WUR. That is, the second to fourth STAs are STAs that wake up through the WUR.

The first PPDU may be transmitted in the first subchannel for the first STA. The second PPDU may be transmitted in the second subchannel for the second STA. The third PPDU may be transmitted in the third subchannel for the third STA. The fourth PPDU may be transmitted in the fourth subchannel for the fourth STA.

The first STA receives the first PPDU in the first subchannel, and determines that the first PPDU is the wakeup null frame through the type subfield. The first STA sleeps by the length of the first PPDU through the length subfield. Accordingly, the first STA may determine that the first subchannel is busy while the first PPDU is transmitted and suspend data transmission and reception. After the first PPDU is transmitted, the first STA may perform channel access to the first subchannel to perform data transmission and reception.

Each of the first to fourth subchannels may be a 20 MHz channel.

The wakeup null frame may have a first data rate or second data. The first data rate may be 62.5 kb / s, and the second data rate may be 250 kb / s.

Channel access for each subchannel is described as follows.

Channel access for the first to fourth subchannels may be performed during a Point Coordination Function (PCF) Interframe Space (PIFS) section immediately before the transmission opportunity (TXOP) starts. The wakeup packet may be transmitted during the TXOP.

Further, when the first to fourth subchannels are idle as a result of performing the channel access, the transmitter may determine whether the pending wakeup packet is present in the first to fourth subchannels.

The first to third sequences may be set to 13 length sequences, 7 length sequences, or the like based on the data rate. The IFFT may be a 64 point IFFT.

In addition, the transmitter may first configure power values of the on signal and the off signal, and configure the on signal and the off signal. The receiver decodes the on signal and the off signal using an envelope detector, thereby reducing power consumed in decoding.

2. Device Configuration

FIG. 28 is a diagram for explaining an apparatus for implementing the method as described above.

The wireless device 100 of FIG. 28 is a transmission device capable of implementing the above-described embodiment and may operate as an AP STA. The wireless device 150 of FIG. 28 is a reception device capable of implementing the above-described embodiment and may operate as a non-AP STA.

The transmitter 100 may include a processor 110, a memory 120, and a transceiver 130, and the receiver device 150 may include a processor 160, a memory 170, and a transceiver 180. can do. The transceiver 130 and 180 may transmit / receive a radio signal and may be executed in a physical layer such as IEEE 802.11 / 3GPP. The processors 110 and 160 are executed in the physical layer and / or the MAC layer and are connected to the transceivers 130 and 180.

The processors 110 and 160 and / or the transceivers 130 and 180 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processors. The memory 120, 170 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and / or other storage unit. When an embodiment is executed by software, the method described above can be executed as a module (eg, process, function) that performs the functions described above. The module may be stored in the memories 120 and 170 and may be executed by the processors 110 and 160. The memories 120 and 170 may be disposed inside or outside the processes 110 and 160, and may be connected to the processes 110 and 160 by well-known means.

The processors 110 and 160 may implement the functions, processes, and / or methods proposed herein. For example, the processors 110 and 160 may perform operations according to the above-described embodiment.

The operation of the processor 110 of the transmitter is specifically as follows. The processor 110 of the transmitting device generates a wakeup packet by applying an On-Off Keying (OOK) method, and transmits the wakeup packet to the receiving device through an 80 MHz channel.

The operation of the processor 160 of the receiving apparatus is as follows. The receiving device may be one of a plurality of low power wake-up receivers. The processor 160 of the receiving device receives a wake-up packet generated by applying an On-Off Keying (OOK) method from a transmitting device through an 80 MHz channel, and decodes the wake-up packet for a band supported by the receiving device. do.

29 illustrates a more detailed wireless device implementing an embodiment of the present invention. The present invention described above with respect to the transmitting apparatus or the receiving apparatus can be applied to this embodiment.

The wireless device includes a processor 610, a power management module 611, a battery 612, a display 613, a keypad 614, a subscriber identification module (SIM) card 615, a memory 620, a transceiver 630. ), One or more antennas 631, speakers 640, and microphones 641.

Processor 610 may be configured to implement the proposed functions, procedures, and / or methods described herein. Layers of the air interface protocol may be implemented in the processor 610. The processor 610 may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and / or a data processing device. The processor may be an application processor (AP). The processor 610 may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modem (modulator and demodulator). Examples of processor 610 include SNAPDRAGONTM series processors manufactured by Qualcomm®, EXYNOSTM series processors manufactured by Samsung®, A Series processors manufactured by Apple®, HELIOTM series processors manufactured by MediaTek®, INTEL® It may be an ATOMTM series processor or a corresponding next generation processor manufactured by.

The power management module 611 manages power of the processor 610 and / or the transceiver 630. The battery 612 supplies power to the power management module 611. The display 613 outputs the result processed by the processor 610. Keypad 614 receives input to be used by processor 610. Keypad 614 may be displayed on display 613. SIM card 615 is an integrated circuit used to securely store an international mobile subscriber identity (IMSI) and its associated keys used to identify and authenticate subscribers in mobile phone devices such as mobile phones and computers. You can also store contact information on many SIM cards.

The memory 620 is operatively coupled with the processor 610 and stores various information for operating the processor 610. The memory 620 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and / or other storage device. When an embodiment is implemented in software, the techniques described herein may be implemented as modules (eg, procedures, functions, etc.) that perform the functions described herein. The module may be stored in the memory 620 and executed by the processor 610. The memory 620 may be implemented inside the processor 610. Alternatively, the memory 620 may be implemented outside the processor 610 and communicatively connected to the processor 610 through various means known in the art.

The transceiver 630 is operatively coupled with the processor 610 and transmits and / or receives a radio signal. The transceiver 630 includes a transmitter and a receiver. The transceiver 630 may include a baseband circuit for processing radio frequency signals. The transceiver controls one or more antennas 631 to transmit and / or receive wireless signals.

The speaker 640 outputs a sound related result processed by the processor 610. The microphone 641 receives a sound related input to be used by the processor 610.

In the case of a transmitter, the processor 610 generates a wakeup packet by applying an On-Off Keying (OOK) scheme, and transmits the wakeup packet to a receiver through an 80 MHz channel.

In the case of a receiving device, the processor 610 receives a wakeup packet generated by applying an On-Off Keying (OOK) method from a transmitting device through an 80 MHz channel and wakes up a band supported by the receiving device. Decode the packet.

How the wakeup packet is configured in the present embodiment is as follows.

The 80 MHz channel includes first to fourth subchannels.

The wakeup packet includes a first PHY protocol data unit (PPDU) transmitted on the first subchannel.

If there is no wakeup packet for the receiver in the first subchannel (if there is no receiver to wake up through the wakeup packet in the first subchannel), the first PPDU is a wakeup null. Frame includes a wake-up null frame and a padding symbol. That is, even if there is no pending wakeup packet in the first subchannel, the state of the first subchannel may be made busy by transmitting the wakeup null frame and the padding symbol. As a result, a third party STA (inter STA or intra STA) may determine that the first subchannel is busy until the wakeup null frame and the padding symbol length, and suspend data transmission.

The wakeup null frame and the padding symbol are transmitted in a first frequency band associated with 13 consecutive subcarriers in the first subchannel. The first frequency band may be a 4 MHz band.

The first subchannel is a primary channel of the 80 MHz channel.

The wake-up null frame may include a frame control field and a FCS field. However, the wakeup null frame may not include an address field, a type dependent control field, and a frame body field.

The frame control field may include a type subfield and a length subfield.

The type subfield may include information that the type of the first PPDU is the wakeup null frame.

The length subfield may include information about the length of the first PPDU.

As a result, the receiving device receiving the wake-up null frame may decode the frame control field and the FCS field. In addition, the receiving apparatus receiving the wake-up null frame detects the type subfield to know that the received frame is the wake-up null frame, and detects the length subfield to pad the padding symbol to a certain point. I can see that.

The wakeup packet may further include a second PPDU transmitted in the second subchannel, a third PPDU transmitted in the third subchannel, and a fourth PPDU transmitted in a fourth subchannel.

The padding symbol may be padded such that the length of the first PPDU is equal to the maximum length of the lengths of the second to fourth PPDUs.

When there is a wakeup signal for the receiver in the second subchannel, the second PPDU may include a first wakeup frame. The first wakeup frame may be generated by inserting a first sequence into 13 consecutive subcarriers in the second subchannel and performing an inverse fast fourier transform (IFFT).

When the wakeup signal for the receiver is present in the third subchannel, the third PPDU may include a second wakeup frame. The second wakeup frame may be generated by inserting a second sequence into 13 consecutive subcarriers in the third subchannel and performing IFFT.

When the wakeup signal for the receiver is present in the fourth subchannel, the fourth PPDU may include a third wakeup frame. The third wakeup frame may be generated by inserting a third sequence into 13 consecutive subcarriers in the fourth subchannel and performing IFFT.

The receiving device may include first to fourth STAs. The first STA may not support a wake-up receiver (WUR). That is, the first STA is not an STA to be woken through the WUR. The second to fourth STAs support WUR. That is, the second to fourth STAs are STAs that wake up through the WUR.

The first PPDU may be transmitted in the first subchannel for the first STA. The second PPDU may be transmitted in the second subchannel for the second STA. The third PPDU may be transmitted in the third subchannel for the third STA. The fourth PPDU may be transmitted in the fourth subchannel for the fourth STA.

The first STA receives the first PPDU in the first subchannel, and determines that the first PPDU is the wakeup null frame through the type subfield. The first STA sleeps by the length of the first PPDU through the length subfield. Accordingly, the first STA may determine that the first subchannel is busy while the first PPDU is transmitted and suspend data transmission and reception. After the first PPDU is transmitted, the first STA may perform channel access to the first subchannel to perform data transmission and reception.

Each of the first to fourth subchannels may be a 20 MHz channel.

The wakeup null frame may have a first data rate or second data. The first data rate may be 62.5 kb / s, and the second data rate may be 250 kb / s.

Channel access for each subchannel is described as follows.

Channel access for the first to fourth subchannels may be performed during a Point Coordination Function (PCF) Interframe Space (PIFS) section immediately before the transmission opportunity (TXOP) starts. The wakeup packet may be transmitted during the TXOP.

Further, when the first to fourth subchannels are idle as a result of performing the channel access, the transmitter may determine whether the pending wakeup packet is present in the first to fourth subchannels.

The first to third sequences may be set to 13 length sequences, 7 length sequences, or the like based on the data rate. The IFFT may be a 64 point IFFT.

In addition, the transmitter may first configure power values of the on signal and the off signal, and configure the on signal and the off signal. The receiver decodes the on signal and the off signal using an envelope detector, thereby reducing power consumed in decoding.

Claims (20)

1. In a method for transmitting a wake-up packet in a wireless LAN system,

   Generating, by the transmitter, a wake-up packet by applying an On-Off Keying (OOK) scheme; And

   Transmitting, by the transmitter, the wakeup packet to a receiver through an 80 MHz channel;

   The 80 MHz channel includes first to fourth subchannels,

   The wakeup packet includes a first PHY protocol data unit (PPDU) transmitted on the first subchannel,

   When there is no wakeup packet for the receiver in the first subchannel, the first PPDU includes a wake-up null frame and a padding symbol.

   The wakeup null frame and the padding symbol are transmitted in a first frequency band associated with 13 consecutive subcarriers in the first subchannel, and

   The first subchannel is a primary channel of the 80 MHz channel.

   Way.
2. The method of claim 1,

   The wake-up null frame includes a frame control field and a FCS (Frame Check Seqeunce) field.

   The frame control field includes a type subfield and a length subfield,

   The type subfield includes information that the type of the first PPDU is the wakeup null frame,

   The length subfield includes information about the length of the first PPDU.

   Way.
3. The method of claim 2,

   The wakeup null frame does not include an address field, a type dependent control field, and a frame body field.

   Way.
4. The method of claim 1,

   The wakeup packet further includes a second PPDU transmitted on the second subchannel, a third PPDU transmitted on the third subchannel, and a fourth PPDU transmitted on a fourth subchannel.

   The padding symbol is padded such that the length of the first PPDU is equal to the maximum length of the lengths of the second to fourth PPDUs.

   Way.
5. The method of claim 4, wherein

   If a wake-up signal for the receiver is present in the second subchannel,

   The second PPDU includes a first wakeup frame,

   The first wakeup frame is generated by inserting a first sequence into 13 consecutive subcarriers in the second subchannel and performing an inverse fast fourier transform (IFFT).

   Way.
6. The method of claim 5,

   If a wake-up signal for the receiver is present in the third subchannel,

   The third PPDU includes a second wakeup frame,

   The second wakeup frame is generated by inserting a second sequence into 13 consecutive subcarriers in the third subchannel and performing IFFT.

   Way.
7. The method of claim 6,

   If a wake-up signal for the receiver is present in the fourth subchannel,

   The fourth PPDU includes a third wakeup frame,

   The third wakeup frame is generated by inserting a third sequence into 13 consecutive subcarriers in the fourth subchannel and performing IFFT.

   Way.
8. The method of claim 7, wherein

   The receiving device includes a first to fourth STA (station),

   The first STA does not support WUR (Wake-Up Receiver),

   The second to fourth STAs support WUR,

   The first PPDU is transmitted in the first subchannel for the first STA,

   The second PPDU is transmitted in the second subchannel for the second STA,

   The third PPDU is transmitted in the third subchannel for the third STA,

   The fourth PPDU is transmitted in the fourth subchannel for the fourth STA.

   Way.
9. The method of claim 1,

   Each of the first to fourth subchannels is a 20 MHz channel.

   Way.
10. The method of claim 1,

    The wake-up null frame has a first data rate or second data,

    The first data rate is 62.5 kb / s,

    The second data rate is 250 kb / s

    Way.
11. A transmitter for transmitting a wake-up packet in a wireless LAN system,

    Memory;

    Transceiver; And

    A processor operatively coupled with the memory and the transceiver, the processor comprising:

    Generating a wake-up packet by applying an On-Off Keying (OOK) scheme; And

    The wake-up packet is transmitted to the receiving device through the 80MHz channel,

    The 80 MHz channel includes first to fourth subchannels,

    The wakeup packet includes a first PHY protocol data unit (PPDU) transmitted on the first subchannel,

    When there is no wakeup packet for the receiver in the first subchannel, the first PPDU includes a wake-up null frame and a padding symbol.

    The wakeup null frame and the padding symbol are transmitted in a first frequency band associated with 13 consecutive subcarriers in the first subchannel, and

    The first subchannel is a primary channel of the 80 MHz channel.

    Transmitter.
12. The method of claim 11,

    The wake-up null frame includes a frame control field and a FCS (Frame Check Seqeunce) field.

    The frame control field includes a type subfield and a length subfield,

    The type subfield includes information that the type of the first PPDU is the wakeup null frame,

    The length subfield includes information about the length of the first PPDU.

    Transmitter.
13. The method of claim 12,

    The wakeup null frame does not include an address field, a type dependent control field, and a frame body field.

    Transmitter.
14. The method of claim 11,

    The wakeup packet further includes a second PPDU transmitted on the second subchannel, a third PPDU transmitted on the third subchannel, and a fourth PPDU transmitted on a fourth subchannel.

    The padding symbol is padded such that the length of the first PPDU is equal to the maximum length of the lengths of the second to fourth PPDUs.

    Transmitter.
15. The method of claim 14,

    If a wake-up signal for the receiver is present in the second subchannel,

    The second PPDU includes a first wakeup frame,

    The first wakeup frame is generated by inserting a first sequence into 13 consecutive subcarriers in the second subchannel and performing an inverse fast fourier transform (IFFT).

    Transmitter.
16. The method of claim 15,

    If a wake-up signal for the receiver is present in the third subchannel,

    The third PPDU includes a second wakeup frame,

    The second wakeup frame is generated by inserting a second sequence into 13 consecutive subcarriers in the third subchannel and performing IFFT.

    Transmitter.
17. The method of claim 16,

    If a wake-up signal for the receiver is present in the fourth subchannel,

    The fourth PPDU includes a third wakeup frame,

    The third wakeup frame is generated by inserting a third sequence into 13 consecutive subcarriers in the fourth subchannel and performing IFFT.

    Transmitter.
18. The method of claim 17,

    The receiving device includes a first to fourth STA (station),

    The first STA does not support WUR (Wake-Up Receiver),

    The second to fourth STAs support WUR,

    The first PPDU is transmitted in the first subchannel for the first STA,

    The second PPDU is transmitted in the second subchannel for the second STA,

    The third PPDU is transmitted in the third subchannel for the third STA,

    The fourth PPDU is transmitted in the fourth subchannel for the fourth STA.

    Transmitter.
19. The method of claim 11,

    The wake-up null frame has a first data rate or second data,

    The first data rate is 62.5 kb / s,

    The second data rate is 250 kb / s

    Transmitter.
20. In a method for receiving a wake-up packet in a wireless LAN system,

    Receiving, by a receiver, a wake-up packet generated by applying an On-Off Keying (OOK) method from a transmitter through an 80 MHz channel; And

    Decoding, by the receiver, the wakeup packet for a channel supported by the receiver;

    The 80 MHz channel includes first to fourth subchannels,

    The wakeup packet includes a first PHY protocol data unit (PPDU) transmitted on the first subchannel,

    When there is no wakeup packet for the receiver in the first subchannel, the first PPDU includes a wake-up null frame and a padding symbol.

    The wakeup null frame and the padding symbol are transmitted in a first frequency band associated with 13 consecutive subcarriers in the first subchannel, and

    The first subchannel is a primary channel of the 80 MHz channel.

    Way.

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