WO2018151446A1 - Method and device for transmitting wake-up packet in wireless lan system - Google Patents

Abstract

A method and device for transmitting a wake-up packet in a wireless LAN system are proposed. Specifically, a transmission device configures a wake-up frame to which an OOK scheme is applied, and transmits the wake-up frame to a reception device. The wake-up frame includes an on signal and an off signal. The on signal includes a signal in which half of a first time domain signal is masked. The first time domain signal is generated by inserting a coefficient into 13 consecutive 20 MHz band subcarriers and performing 64-point IFFT on the same.

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 frame to a WLAN system.

This embodiment may be operated in a transmitter, the receiver may correspond to a low power wake-up receiver, and the transmitter may correspond to an AP.

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 configures a wake-up frame to which the OOK (On-Off Keying) method is applied.

The transmitter transmits the wakeup frame to the receiver.

How the wake-up frame is configured is as follows.

The wakeup frame includes an on signal and an off signal.

The on signal consists of a signal masking half of the first time domain signal. Here, masking may correspond to a technique of covering a part of a signal and taking only a part of the signal. Accordingly, the on signal may be configured as a signal that masks half of the first time domain signal or half of the first time domain signal.

The first time-domain signal is generated by inserting a coefficient into 13 consecutive subcarriers in a 20 MHz band and performing a 64-point Inverse Fast Fourier Transform (IFFT). Coefficients may be inserted in all 13 subcarriers. In this case, the first time-domain signal may be a signal having a length of 3.2us having no period. The coefficient can be selected from 1, -1, j or -j.

As another example, coefficients may be inserted in units of two subcarriers in the thirteen subcarriers, and zero may be inserted in the remaining subcarriers. In this case, the first time-domain signal may be a 3.2us signal having a period of 1.6us.

As another example, coefficients may be inserted in units of four subcarriers in the thirteen subcarriers, and zero may be inserted in the remaining subcarriers. In this case, the first time-domain signal may be a 3.2us signal having a period of 0.8us.

As another example, coefficients may be inserted in units of 8 subcarriers in the 13 subcarriers and 0 may be inserted in the remaining subcarriers. In this case, the first time-domain signal may be a 3.2us signal having a period of 0.4us.

Half of the first time domain signal may be masked without a cyclic prefix (CP) being inserted into the first time domain signal. In this case, the on signal may be configured as a signal in which a CP is further inserted into the masked signal. That is, the transmitting device may configure an ON signal by inserting a CP into a 1.6us signal, which is half of the 3.2us signal (CP + 1.6us). In this case, the inserted CP may have a length of 0.4 us and the on signal may have a length of 2 us (CP + 1.6us).

In addition, a CP may be inserted into the first time domain signal to mask half of the first time domain signal. That is, the on signal may be configured by masking a first time domain signal in which CP is inserted. In other words, a 2us on signal may be constructed by first generating a 4us OOK symbol and masking half of the 4us OOK symbol. The inserted CP may have a length of 0.8 us. This is because the 4us OOK symbol must be created first (CP + 3.2us). The on signal may have a length of 2 us (CP ′ + 1.6 us).

The off signal may be configured as a signal masking half of the second time domain signal. The second time domain signal may be generated by inserting 0 into 13 consecutive subcarriers in a 20 MHz band and performing a 64-point IFFT. The off signal may have a length of 2us (CP + 1.6us).

The wakeup frame may include a symbol for transmitting first information or second information. The first information may be configured in the order of the on signal and the off signal. The second information may be configured in the order of the off signal and the on signal. On the contrary, the first information may be configured in the order of the off signal and the on signal. The second information may be configured in the order of the on signal and the off signal. That is, a wakeup frame to which the Manchester coding technique is applied may be configured based on signal masking.

The first information or the second information may correspond to logical information transmitted in symbol units. For example, the first information may be transmitted through an on symbol, and the second information may be transmitted through an off symbol. And vice versa.

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, the transmitter can configure the unified signal for all symbol types on the basis of signal masking, thereby reducing the complexity of the transmitter.

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

15 is a block diagram illustrating a wireless device to which the present embodiment can be applied.

16 is a block diagram illustrating an example of an apparatus included in a processor.

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 a 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 spaces 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 to determine information 0 (0 0) if the value is less than 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, n 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. In fact, 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). At this time, if the symbol is repeated twice using the symbol repetition technique, the data rate may be 125 Kbps (8us), and if the fourth repetition is performed, the data rate may be 62.5 Kbps (16us), and if the eight times are repeated, the data rate may be 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 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.

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, a symbol carrying one piece of information becomes CP + 0.4us, and thus a 0.5us off signal or a 0.5us on signal is composed 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

In addition, the following proposes a method for configuring the OOK symbol used in various symbol types in the 802.11ba system, and in particular focusing on the method for configuring the ON-signal.

As described above, various symbol types for WUR support may be considered, and a configuration method of an on signal may be considered differently according to each symbol type. However, if the on-signal is configured differently for each symbol type, the complexity of the transmitting apparatus can be increased. Therefore, it is effective to unify the method of configuring the on-signal in all the symbol types. To this end, this patent proposes various on-signal construction methods that can be used in each symbol type and proposes a unified configuration method according to the symbol types used in the WUR.

Assuming that a conventional Wi-Fi transmitter is used, transmission of a WUR frame using a subcarrier of some of 64 subcarriers in total of 20 MHz is considered. When 11ax is used, the transmission of the wakeup frame may be assumed using only a part of the total 256 subcarriers, and the transmission of the wakeup frame may be assumed using the RU of a part of the OFDMA tone plan. In this case, an appropriate coefficient is inserted into a subcarrier available for configuring an on signal, and 0 is inserted into a subcarrier not used. 0 may be inserted into DC among the available subcarriers. The coefficient to be inserted may be set to a value that optimizes PAPR. The coefficient to be inserted can be selected from 1 or -1 or from 1, -1, j, -j. In addition, some of the available subcarriers may be inserted with a coefficient of zero according to a specific scheme. Insert coefficients into subcarriers and apply 64 IFFTs (256 IFFTs in 11ax) to form 3.2us signals in the time domain and use all of the time domain signals formed for the on-signals, or apply some Can be used and CP can be applied. CP may be 0.4us or 0.8us and other values. Hereinafter, various on signal configuration methods will be described.

1. Insert coefficients into all available subcarriers

Insert a coefficient into all available subcarriers. DC can insert zeros and subcarriers that are not available insert zeros. In this case, the application of IFFT creates a 3.2us time-domain signal with no specific repetition (with no specific period), and thus can be used for a typical OOK symbol or symbol repetition type among various symbol types.

A. Common OOK Symbol Types

Using the 3.2us signal generated previously, CP + 3.2us can be configured and used as an ON-symbol to inform information 1. OFF-symbols can be formed by not transmitting any information for a time equal to CP + 3.2us and announce information zero.

B. Symbol Repeat Type

The signal generated by CP + 3.2us is created using the 3.2us signal generated previously, and the off signal is configured by not transmitting any information for the same time. This may be repeated to configure a symbol for notifying information 0 or information 1 in the symbol repetition type. For example, a symbol for notifying information 1 may be configured by repeating the on signal and conversely, a symbol for notifying information 0 may be configured by repeating the off signal. Alternatively, each symbol may be configured using both an on signal and an off signal.

For example, Manchester coding may be applied to configure a transition in the center of the symbol. Considering the symbol of the second repetition, a symbol for indicating information 0 may be configured as ON-signal + OFF-signal, and vice versa, a symbol for indicating information 1 may be configured as OFF-signal + ON-signal. Or the opposite.

2. Insert coefficients in two spaces on all available subcarriers

Insert a coefficient in two spaces on all available subcarriers. 0 is inserted in the other subcarriers, DC can also be inserted 0, and 0 is inserted even in subcarriers that are not available. In this case, applying IFFT creates a 3.2us time-domain signal with a period of 1.6us and can be used for the general OOK symbol, symbol repetition type, Manchester coding based symbol type, or 1/2 symbol reduction type among various symbol types.

A. Common OOK Symbol Types

All of the 3.2us signals having the 1.6us period generated previously can be configured as CP + 3.2us and used as an on symbol for informing information 1. The off symbol can be configured by not transmitting any information as much as CP + 3.2us time and inform information 0.

B. Symbol Coding Based on Manchester Coding

An on-signal of CP + 1.6us can be configured by using the first or last 1.6us portion of the 3.2us signal having the 1.6us period generated previously and inserting CP therein. It is also possible to form an off signal by not transmitting any information as much as CP + 1.6us. By using the generated on signal and the off signal, a symbol for notifying information 0 or information 1 may be configured. For example, a symbol for notifying information 0 may be configured as ON-signal + OFF-signal, whereas a symbol for notifying information 1 may be configured as OFF-signal + ON-signal. Or the opposite.

C. Symbol Repeat Type

Using the 3.2us signal with the 1.6us period above, CP + 3.2us is used to make an on-signal, and no information is transmitted for the same time. By repeating this, a symbol for informing information 0 or information 1 may be configured. For example, a symbol for notifying information 1 may be configured by repeating an on signal, and conversely, a symbol for notifying information 0 may be configured by repeating an off signal. Alternatively, each symbol may be configured using both an on signal and an off signal.

For example, Manchester coding may be applied to configure a transition in the center of a symbol. Considering the symbol of the second repetition, a symbol for indicating information 0 may be configured as ON-signal + OFF-signal, and vice versa, a symbol for indicating information 1 may be configured as OFF-signal + ON-signal. Or the opposite.

Meanwhile, a symbol for notifying information 0 or information 1 may be configured by repeating a symbol coding based on Manchester coding. That is, by using the first or last 1.6us portion of the 3.2us signal having a 1.6us period and inserting a CP therein, a CP + 1.6us on signal is formed and no information is transmitted as much as CP + 1.6us. After constructing the symbol can be configured using this.

For example, if a symbol type based on Manchester coding considers a symbol repeated twice, a symbol for indicating information '0' may consist of ON-signal + OFF-signal + ON-signal + OFF-signal and vice versa. The symbol may consist of OFF-signal + ON-signal + OFF-signal + ON-signal. Or the opposite.

D. 1/2 Symbol Reduction Type

An on-signal of CP + 1.6us may be configured by using the first or last 1.6us portion of the 3.2us signal having the 1.6us period and inserting a CP therein, which may be an on-signal for indicating information 1. In addition, it is possible to configure the off signal by not transmitting any information as much as CP + 1.6us, which may be an off symbol for notifying information 0.

3. Insert coefficients in four spaces on all available subcarriers

Insert a coefficient in four spaces on all available subcarriers. Other subcarriers insert zeros and DCs can also insert zeros, while non-available subcarriers insert zeros. In this case, applying IFFT produces a 3.2us time-domain signal with a period of 0.8us, which can be applied to a typical OOK symbol, symbol repetition type, Manchester coding-based symbol type, or 1/2, 1/4 symbol reduction type among various symbol types. Can be used.

A. Common OOK Symbol Types

All of the 3.2us signals generated with the 0.8us period previously generated can be configured as CP + 3.2us and used as an on symbol for informing information 1. The off symbol can be formed by not transmitting any information for a time as CP + 3.2us and announces information zero.

B. Symbol Coding Based on Manchester Coding

Select the first, second or third or last 0.8us portion of the 3.2us signal with the 0.8us period generated earlier and repeat it twice (or take the first 1.6us or last 1.6us) and insert the CP here CP + 1.6us on signal can be configured. It is also possible to form an off signal by not transmitting any information as much as CP + 1.6us. By using the generated on signal and the off signal, a symbol for notifying information 0 or information 1 may be configured. For example, a symbol for notifying information 0 may be configured as ON-signal + OFF-signal, whereas a symbol for notifying information 1 may be configured as OFF-signal + ON-signal. Or the opposite.

C. Symbol Repeat Type

CP + 3.2us is composed of all 3.2us signals with the 0.8us period generated earlier, and the off signal is constructed by not transmitting any information for the same time. By repeating this, a symbol for informing information 0 or information 1 may be configured. For example, a symbol for notifying information 1 may be configured by repeating an on signal, and conversely, a symbol for notifying information 0 may be configured by repeating an off signal. Alternatively, each symbol may be configured using both an on signal and an off signal. For example, Manchester coding may be applied to configure a transition in the center of a symbol. Considering the symbol of the second repetition, a symbol for indicating information 0 may be configured as ON-signal + OFF-signal, and vice versa, a symbol for indicating information 1 may be configured as OFF-signal + ON-signal. Or the opposite.

Meanwhile, a symbol for notifying information 0 or information 1 may be configured by repeating a symbol coding based on Manchester coding. That is, a 3.2us signal with a 0.8us period, the first, second, or third or last 0.8us part is selected and repeated twice (or the first 1.6us or the last 1.6us may be taken), and the CP is inserted into the CP. By configuring the on-signal of + 1.6us and not transmitting any information as much as CP + 1.6us, the off-signal may be configured and then the symbol may be configured using the same. For example, if the symbol coding based on the Manchester coding type considers a symbol that is repeated twice, the symbol for indicating information 0 may be composed of ON-signal + OFF-signal + ON-signal + OFF-signal, and vice versa. Can consist of OFF-signal + ON-signal + OFF-signal + ON-signal. Or the opposite.

D. 1/2 Symbol Reduction Type

Select the first, second or third or last 0.8us portion of the 3.2us signal with the 0.8us period generated earlier and repeat it twice (or take the first 1.6us or last 1.6us) and insert the CP here In this case, an on signal of CP + 1.6us may be configured, which may be an on symbol for informing information 1. In addition, it is possible to configure the off signal by not transmitting any information as much as CP + 1.6us, which may be an off symbol for notifying information 0.

E. 1/4 Symbol Reduction Type

The on signal of CP + 0.8us can be configured by using the first, second, third or last 0.8us part of the 3.2us signal with the 0.8us period generated previously and inserting CP into it. It may be an on symbol for informing. In addition, an off signal may be configured by not transmitting any information as much as CP + 0.8us, which may be an off symbol for indicating information 0. The length of CP may be 0.2us as well as 0.4us and 0.8us mentioned above.

4. Insert coefficients in eight positions on all available subcarriers

Inserts a coefficient in eight spaces on all available subcarriers. Other subcarriers insert zeros and DCs can also insert zeros, while non-available subcarriers insert zeros. In this case, IFFT results in a 3.2us time-domain signal with a period of 0.4us, which is a common OOK symbol, symbol repetition type, Manchester coding based symbol type, or 1/2, 1/4, 1/8 Can be used for symbol reduction types.

A. Common OOK Symbol Types

All of the 3.2us signals having the 0.4us period generated previously can be configured as CP + 3.2us and used as an on symbol for informing information 1. The off symbol can be configured by not transmitting any information as much as CP + 3.2us time and inform information 0.

B. Symbol Coding Based on Manchester Coding

Select the first or second or third or fourth or fifth or sixth or seventh or last 0.4us part of the 3.2us signal with the 0.4us period generated earlier and repeat it four times (first 1.6us or last). It can take 1.6us) You can insert a CP here to configure an on signal of CP + 1.6us. It is also possible to form an off signal by not transmitting any information as much as CP + 1.6us. By using the generated on signal and the off signal, a symbol for notifying information 0 or information 1 may be configured. For example, a symbol for notifying information 0 may be configured as ON-signal + OFF-signal, whereas a symbol for notifying information 1 may be configured as OFF-signal + ON-signal. Or the opposite.

C. Symbol Repeat Type

CP-3.2us is composed of all 3.2us signals with the 0.4us period above to make ON-signal and OFF-signal is not transmitted by sending any information for the same time. By repeating this, a symbol for informing information 0 or information 1 may be configured. For example, a symbol indicating information 1 may be configured by repeating ON-signal, whereas a symbol indicating information 0 may be configured by repeating OFF-signal. Alternatively, each symbol can be configured using both ON-signal and OFF-signal.

For example, Manchester coding may be applied to configure a transition in the center of a symbol. Considering the symbol of the second repetition, a symbol for indicating information 0 may be configured as ON-signal + OFF-signal, and vice versa, a symbol for indicating information 1 may be configured as OFF-signal + ON-signal. Or the opposite.

Meanwhile, a symbol for notifying information 0 or information 1 may be configured by repeating a symbol coding based on Manchester coding. In other words, the first or second or third or fourth or fifth or sixth or seventh or last 0.4us portions of a 3.2us signal having a 0.4us period are selected and repeated four times (first 1.6us or last 1.6). It can take us) You can insert a CP here to configure CP + 1.6us ON-signal and send no information as much as CP + 1.6us to configure OFF-signal and then use it to construct a symbol. . For example, if the symbol coding based on the Manchester coding type considers a symbol that is repeated twice, the symbol for indicating information 0 may be composed of ON-signal + OFF-signal + ON-signal + OFF-signal, and vice versa. Can consist of OFF-signal + ON-signal + OFF-signal + ON-signal. Or the opposite.

D. 1/2 Symbol Reduction Type

Select the first or second or third or fourth or fifth or sixth or seventh or last 0.4us portions of the 3.2us signal with the 0.4us period generated earlier and repeat it four times (first 1.6us or last). It can also take 1.6us) by inserting the CP to configure the ON-signal of CP + 1.6us, which may be an on symbol to inform information 1. In addition, it may form an OFF-signal by not transmitting any information as much as CP + 1.6us, which may be an off symbol for indicating information 0.

E. 1/4 Symbol Reduction Type

Select the first or second or third or fourth or fifth or sixth or seventh or last 0.4us portions of the 3.2us signal with the 0.4us period generated earlier and repeat it twice (first 0.8us or two). The first 0.8us or the third 0.8us or the last 0.8us may be taken.) The CP may be inserted to form an ON-signal of CP + 0.8us, which may be an on symbol for informing information 1. In addition, it may form an OFF-signal by not transmitting any information as much as CP + 0.8us, which may be an off symbol for indicating information 0. The length of CP may be 0.2us as well as 0.4us and 0.8us mentioned above. Or any other value.

F. 1/8 Symbol Reduction Type

Using the first or second or third or fourth or fifth or sixth or seventh or last 0.4us parts of the 3.2us signal having the 0.4us period generated earlier, CP + 0.4us The ON-signal of may be configured, which may be an on symbol for informing information 1. In addition, it may form an OFF-signal by not transmitting any information as much as CP + 0.4us, which may be an off symbol for indicating information 0. The length of CP may be 0.1us as well as 0.4us and 0.8us mentioned above. Or any other value.

5. Unification and CP length of the structure of the on signal

When various symbol types are used, the complexity of the transmitter can be reduced by unifying the configuration of the ON-signal. For example, only generic OOK symbols, symbol repetition types, Manchester coding based symbol types, or 1/2 symbol reduction types can be used in the WUR, in which case two spaces (four spaces, It is possible to unify the method of constructing the ON-signal by inserting coefficients in units of 8). In this case, the CP length of the general OOK type for each ON-signal or OFF-signal may be 0.8us, and the CP length of the Manchester coding-based OOK type and the 1/2 symbol reduction type may be 0.4us. The CP length of the symbol repetition type may be 0.8us when repeating a general OOK type and 0.4us when repeating a OOK type based on Manchester coding. In this case, the total CP length per symbol is a typical OOK, Manchester coding-based OOK symbol type is 0.8us, 1/2 symbol reduction type is 0.4us, symbol repetition type is 0.8us * repeated number. Also, the length of one symbol in each type is

Normal OOK symbol	Manchester coding based OOK symbol		symbol repetition	1/2 symbol reduction
4us	4us	4us * repeat count	2us

The symbol repetition type can only be used twice.

On the other hand, only a generic OOK, Manchester coding-based OOK symbol, and a double repetition symbol repetition type can be used in the WUR, in which case two (four or eight) units are available for all available subcarriers in the four configuration methods above. You can unify the construction of the ON-signal by inserting the coefficients. In this case, the CP length of the general OOK symbol type for each ON-signal or OFF-signal may be 0.8us, and the CP length of the Manchester coding-based symbol type may be 0.4us. The CP length of the symbol repetition type may be 0.8us when repeating a general OOK symbol type, and 0.4us when repeating a OOK type based on Manchester coding. In this case, the total CP length per symbol is 0.8us for a typical OOK, OOK symbol type based on Manchester coding, and 1.6us for a symbol repetition type. Also, the length of one symbol in each type is

Normal OOK symbol	Manchester coding based OOK symbol	symbol repetition
4us	4us	8us

On the other hand, only a normal OOK, a two-repeat symbol repetition type, can be used in the WUR, in which case the coefficients are inserted in all available subcarriers (two, four, eight) It is possible to unify the method of configuring ON-signal. In this case, the CP length of both types may be 0.8us for each ON-signal or OFF-signal. In this case, the total CP length per symbol is 0.8us for a typical OOK symbol type and 1.6us for a symbol repetition type. Also, the length of one symbol in each type is

Normal OOK symbol	symbol repetition
4us	8us

On the other hand, only Manchester coding-based OOK symbols and two repeating symbol repetition types can be used in the WUR, in which case all four available subcarriers count in units of two (four or eight). You can unify the ON-signal construction method by inserting. In this case, for each ON-signal or OFF-signal, both types of CP length may be 0.4us. In this case, the length of the total CP per symbol is 0.8us for the OOK symbol type based on Manchester coding, and 1.6us for the symbol repetition type. Also, the length of one symbol in each type is

Manchester coding based OOK symbol	symbol repetition
4us	8us

On the other hand, only the common OOK and Manchester coding-based OOK symbol types can be used in WUR, in which case the coefficients are inserted in units of two spaces (four or eight) in all of the available subcarriers. It is possible to unify the method of configuring ON-signal. In this case, the CP length of the general OOK type for each ON-signal or OFF-signal may be 0.8us, and the CP length of the Manchester coding-based OOK symbol type may be 0.4us. In this case, the total CP length per symbol is 0.8us for both types. Also, the length of one symbol in each type is

Normal OOK symbol	Manchester coding based OOK symbol
4us	4us

6. Alternative ways

Insert a coefficient into all available subcarriers or insert a coefficient in units of two, four, or eight columns. DC can insert zeros and subcarriers that are not available insert zeros. In this case, the application of IFFT creates a 3.2us time-domain signal with no specific repetition or a period of 1.6us or 0.8us or 0.4us and can be applied to all symbol types. However, this paper proposes a method of constructing on-signal according to all symbol types with a 3.2us signal obtained by applying IFFT by inserting coefficients into all available subcarriers.

A. Common OOK Symbol Types

CP + 3.2us can be used by using all of the 3.2us signals generated above, and this can be used as an on symbol to inform information 1. The off symbol can be formed by not transmitting any information for a time as CP + 3.2us and announces information zero.

B. Symbol Coding Based on Manchester Coding

You can configure CP + 1.6us ON-signal by taking the first 1.6us or last 1.6us from the 3.2us signal generated earlier and inserting CP into it. Alternatively, ON-signal may be configured by taking the first CP + 1.6us or the last CP + 1.6us from the previously generated CP + 3.2us signal (4us). In addition, OFF-signal can be formed by not transmitting any information as CP + 1.6us. Using the generated ON-signal and OFF-signal, a symbol for informing information 0 or information 1 can be constructed. For example, a symbol for indicating information 0 may be configured as ON-signal + OFF-signal, whereas a symbol for indicating information 1 may be configured as OFF-signal + ON-signal. Or the opposite.

C. Symbol Repeat Type

CP-3.2us is used to make up the ON-signal using all the 3.2us signals generated previously, and OFF-signal is configured by not transmitting any information for the same time. By repeating this, a symbol for informing information 0 or information 1 may be configured. For example, a symbol indicating information 1 may be configured by repeating ON-signal, whereas a symbol indicating information 0 may be configured by repeating OFF-signal. Alternatively, each symbol can be configured using both ON-signal and OFF-signal. For example, Manchester coding may be applied to configure a transition in the center of a symbol. Considering the symbol of the second repetition, a symbol for indicating information 0 may be configured as ON-signal + OFF-signal, and vice versa, a symbol for indicating information 1 may be configured as OFF-signal + ON-signal. Or the opposite.

Meanwhile, a symbol for notifying information 0 or information 1 may be configured by repeating a symbol coding based on Manchester coding. That is, an ON-signal of CP + 1.6us can be configured by taking the first 1.6us or the last 1.6us from the 3.2us signal generated previously and inserting CP therein. Alternatively, ON-signal may be configured by taking the first CP + 1.6us or the last CP + 1.6us from the previously generated CP + 3.2us signal (4us). You can also configure OFF-signal by not sending any information as CP + 1.6us. Symbols can be constructed using these ON-signal and OFF-signal. For example, if the symbol coding based on the Manchester coding type considers a symbol that is repeated twice, the symbol for indicating information 0 may be composed of ON-signal + OFF-signal + ON-signal + OFF-signal, and vice versa. Can consist of OFF-signal + ON-signal + OFF-signal + ON-signal. Or the opposite.

D. 1/2 Symbol Reduction Type

The first 1.6us or last 1.6us of the 3.2us signal generated earlier can be taken and CP can be inserted into the CP + 1.6us ON-signal. Alternatively, ON-signal may be configured by taking the first CP + 1.6us or the last CP + 1.6us from the previously generated CP + 3.2us signal (4us). This may be an on symbol for informing information 1. In addition, it may form an OFF-signal by not transmitting any information as much as CP + 1.6us, which may be an off symbol for indicating information 0.

E. 1/4 Symbol Reduction Type

The first 0.8us or the last 0.8us of the 3.2us signal generated previously can be taken and CP can be inserted to form an ON-signal of CP + 0.8us. Alternatively, ON-signal may be configured by taking the first CP + 0.8us or the last CP + 0.8us from the previously generated CP + 3.2us signal (4us). This may be an on symbol for informing information 1. In addition, it may form an OFF-signal by not transmitting any information as much as CP + 0.8us, which may be an off symbol for indicating information 0. The length of CP may be 0.2us as well as 0.4us and 0.8us mentioned above. Or any other value.

F. 1/8 Symbol Reduction Type

The first 0.4us or the last 0.4us of the 3.2us signals generated previously can be taken and CP can be inserted into the CP + 0.4us ON-signal. Alternatively, ON-signal may be configured by taking the first CP + 0.4us or the last CP + 0.4us from the previously generated CP + 3.2us signal (4us). This may be an on symbol for informing information 1. In addition, it may form an OFF-signal by not transmitting any information as much as CP + 0.4us, which may be an off symbol for indicating information 0. The length of CP may be 0.1us as well as 0.4us and 0.8us mentioned above. Or any other value.

In addition, one symbol to which the Manchester coding scheme is applied may be formed using both ON-signal and OFF-signal formed in each of the 1/2, 1/4, and 1/8 symbol reduction types described above. For example, a symbol for notifying information 0 may be configured as ON-signal + OFF-signal, whereas a symbol for notifying information 1 may be configured as OFF-signal + ON-signal. Or the opposite.

At this time, if the 1/2 symbol reduction type is applied, the ON-signal or OFF-signal may be configured as CP + 1.6us. If the 1/4 symbol reduction type is applied, the ON-signal or OFF-signal may be configured as CP + 0.8us. If the 1/8 symbol reduction type is applied, the ON-signal or OFF-signal may be configured as CP + 0.4us.

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.

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

An example of FIG. 14 is performed in a transmitter, the receiver may correspond to a low power wake-up receiver, and the transmitter may correspond to an AP.

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 S1410, the transmitter configures a wake-up packet to which the On-Off Keying (OOK) method is applied.

In operation S1420, the transmitter transmits the wakeup frame to the receiver.

How the wake-up frame is configured is as follows.

The wakeup frame includes an on signal and an off signal.

The on signal consists of a signal masking half of the first time domain signal. Here, masking may correspond to a technique of covering a part of a signal and taking only a part of the signal. Accordingly, the on signal may be configured as a signal that masks half of the first time domain signal or half of the first time domain signal.

The first time-domain signal is generated by inserting a coefficient into 13 consecutive subcarriers in a 20 MHz band and performing a 64-point Inverse Fast Fourier Transform (IFFT). Coefficients may be inserted in all 13 subcarriers. In this case, the first time-domain signal may be a signal having a length of 3.2us having no period. The coefficient can be selected from 1, -1, j or -j.

As another example, coefficients may be inserted in units of two subcarriers in the thirteen subcarriers, and zero may be inserted in the remaining subcarriers. In this case, the first time-domain signal may be a 3.2us signal having a period of 1.6us.

As another example, coefficients may be inserted in units of four subcarriers in the thirteen subcarriers, and zero may be inserted in the remaining subcarriers. In this case, the first time-domain signal may be a 3.2us signal having a period of 0.8us.

As another example, coefficients may be inserted in units of 8 subcarriers in the 13 subcarriers and 0 may be inserted in the remaining subcarriers. In this case, the first time-domain signal may be a 3.2us signal having a period of 0.4us.

Half of the first time domain signal may be masked without a cyclic prefix (CP) being inserted into the first time domain signal. In this case, the on signal may be configured as a signal in which a CP is further inserted into the masked signal. That is, the transmitting device may configure an ON signal by inserting a CP into a 1.6us signal, which is half of the 3.2us signal (CP + 1.6us). In this case, the inserted CP may have a length of 0.4 us and the on signal may have a length of 2 us (CP + 1.6us).

In addition, a CP may be inserted into the first time domain signal to mask half of the first time domain signal. That is, the on signal may be configured by masking a first time domain signal in which CP is inserted. In other words, a 2us on signal may be constructed by first generating a 4us OOK symbol and masking half of the 4us OOK symbol. The inserted CP may have a length of 0.8 us. This is because the 4us OOK symbol must be created first (CP + 3.2us). The on signal may have a length of 2 us (CP ′ + 1.6 us).

The off signal may be configured as a signal masking half of the second time domain signal. The second time domain signal may be generated by inserting 0 into 13 consecutive subcarriers in a 20 MHz band and performing a 64-point IFFT. The off signal may have a length of 2us (CP + 1.6us).

The wakeup frame may include a symbol for transmitting first information or second information. The first information may be configured in the order of the on signal and the off signal. The second information may be configured in the order of the off signal and the on signal. On the contrary, the first information may be configured in the order of the off signal and the on signal. The second information may be configured in the order of the on signal and the off signal. That is, a wakeup frame to which the Manchester coding technique is applied may be configured based on signal masking.

The first information or the second information may correspond to logical information transmitted in symbol units. For example, the first information may be transmitted through an on symbol, and the second information may be transmitted through an off symbol. And vice versa.

The symbol for transmitting the first information or the second information may have a length of 4 us.

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.

15 is a block diagram illustrating a wireless device to which the present embodiment can be applied.

Referring to FIG. 15, a wireless device may be implemented as an AP or a non-AP STA as an STA capable of implementing the above-described embodiment. In addition, the wireless device may correspond to the above-described user or may correspond to a transmission device for transmitting a signal to the user.

The wireless device of FIG. 15 includes a processor 1510, a memory 1520, and a transceiver 1530 as shown. The illustrated processor 1510, memory 1520, and transceiver 1530 may be implemented as separate chips, or at least two blocks / functions may be implemented through one chip.

The transceiver 1530 is a device including a transmitter and a receiver. When a specific operation is performed, only one of the transmitter and the receiver may be performed, or both the transmitter and the receiver may be performed. Can be. The transceiver 1530 may include one or more antennas for transmitting and / or receiving wireless signals. In addition, the transceiver 1530 may include an amplifier for amplifying a reception signal and / or a transmission signal and a bandpass filter for transmission on a specific frequency band.

The processor 1510 may implement the functions, processes, and / or methods proposed herein. For example, the processor 1510 may perform an operation according to the above-described embodiment. That is, the processor 1510 may perform the operations disclosed in the embodiments of FIGS. 1 to 14.

The processor 1510 may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, a data processing device, and / or a converter for translating baseband signals and wireless signals. Memory 1520 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices.

16 is a block diagram illustrating an example of an apparatus included in a processor. For convenience of description, an example of FIG. 16 is described with reference to a block for a transmission signal, but it is obvious that the reception signal can be processed using the block.

The illustrated data processor 1610 generates transmission data (control data and / or user data) corresponding to the transmission signal. The output of the data processor 1610 may be input to the encoder 1620. The encoder 1620 may perform coding through a binary convolutional code (BCC) or a low-density parity-check (LDPC) technique. At least one encoder 1620 may be included, and the number of encoders 1620 may be determined according to various information (eg, the number of data streams).

The output of the encoder 1620 may be input to the interleaver 1630. The interleaver 1630 performs an operation of distributing consecutive bit signals over radio resources (eg, time and / or frequency) to prevent burst errors due to fading or the like. At least one interleaver 1630 may be included, and the number of the interleaver 1630 may be determined according to various information (for example, the number of spatial streams).

The output of the interleaver 1630 may be input to a constellation mapper 1640. The constellation mapper 1640 performs constellation mapping such as biphase shift keying (BPSK), quadrature phase shift keying (QPSK), quadrature amplitude modulation (n-QAM), and the like.

The output of the constellation mapper 1640 may be input to the spatial stream encoder 1650. The spatial stream encoder 1650 performs data processing to transmit the transmission signal through at least one spatial stream. For example, the spatial stream encoder 1650 may perform at least one of space-time block coding (STBC), cyclic shift diversity (CSD) insertion, and spatial mapping on a transmission signal.

The output of the spatial stream encoder 1650 may be input to an IDFT 1660 block. The IDFT 1660 block performs inverse discrete Fourier transform (IDFT) or inverse Fast Fourier transform (IFFT).

The output of the IDFT 1660 block is input to the Guard Interval (GI) inserter 1670, and the output of the GI inserter 1670 is input to the transceiver 1530 of FIG. 15.

Claims (14)

1. In the method for transmitting a wake-up frame (wire-up frame) in a wireless LAN system,

   Configuring, by the transmitter, a wake-up frame to which an On-Off Keying (OOK) scheme is applied; And

   Transmitting, by the transmitter, the wakeup frame to a receiver;

   The wakeup frame includes an on signal and an off signal.

   The on signal is composed of a signal masking half of the first time domain signal,

   The first time-domain signal is generated by inserting coefficients into 13 consecutive subcarriers of 20 MHz band and performing 64-point Inverse Fast Fourier Transform (IFFT).

   Way.
2. The method of claim 1,

   When CP is not inserted into the first time domain signal and half of the first time domain signal is masked,

   The on signal is composed of a signal in which a CP is further inserted into the masked signal,

   The inserted CP has a length of 0.4 us,

   The on signal has a length of 2us

   Way.
3. The method of claim 1,

   When a CP is inserted into the first time domain signal so that half of the first time domain signal is masked,

   The inserted CP has a length of 0.8 us,

   The on signal has a length of 2us

   Way.
4. The method of claim 1,

   The off signal is composed of a signal masking half of the second time domain signal,

   The second time domain signal is generated by inserting 0 into 13 consecutive subcarriers in the 20 MHz band and performing a 64-point IFFT.

   The off signal has a length of 2us.

   Way.
5. The method of claim 4, wherein

   The wakeup frame includes a symbol for transmitting first information or second information,

   The first information is configured in the order of the on signal and the off signal,

   The second information is configured in the order of the off signal and the on signal;

   The symbol for transmitting the first information or the second information has a length of 4 us.

   Way.
6. The method of claim 1,

   Coefficients are inserted into all 13 subcarriers,

   The first time domain signal is a signal having a length of 3.2 us without a period.

   Way.
7. The method of claim 6,

   The coefficient is selected from 1, -1, j or -j

   Way.
8. A transmitter for transmitting a wake-up frame in a wireless LAN system,

   A transceiver for transmitting or receiving a wireless signal; And

   A processor for controlling the transceiver, the processor comprising:

   Configure a wake-up frame to which the On-Off Keying (OOK) method is applied, and

   Send the wake-up frame to the receiving device,

   The wakeup frame includes an on signal and an off signal.

   The on signal is composed of a signal masking half of the first time domain signal,

   The first time-domain signal is generated by inserting coefficients into 13 consecutive subcarriers of 20 MHz band and performing 64-point Inverse Fast Fourier Transform (IFFT).

   Transmitter.
9. The method of claim 8,

   When CP is not inserted into the first time domain signal and half of the first time domain signal is masked,

   The on signal is composed of a signal in which a CP is further inserted into the masked signal,

   The inserted CP has a length of 0.4 us,

   The on signal has a length of 2us

   Transmitter.
10. The method of claim 8,

    When a CP is inserted into the first time domain signal so that half of the first time domain signal is masked,

    The inserted CP has a length of 0.8 us,

    The on signal has a length of 2us

    Way.
11. The method of claim 8,

    The off signal is composed of a signal masking half of the second time domain signal,

    The second time domain signal is generated by inserting 0 into 13 consecutive subcarriers in the 20 MHz band and performing a 64-point IFFT.

    The off signal has a length of 2us.

    Transmitter.
12. The method of claim 11,

    The wakeup frame includes a symbol for transmitting first information or second information,

    The first information is configured in the order of the on signal and the off signal,

    The second information is configured in the order of the off signal and the on signal;

    The symbol for transmitting the first information or the second information has a length of 4 us.

    Transmitter.
13. The method of claim 8,

    Coefficients are inserted into all 13 subcarriers,

    The first time domain signal is a signal having a length of 3.2 us without a period.

    Transmitter.
14. The method of claim 13,

    The coefficient is selected from 1, -1, j or -j

    Transmitter.

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