WO2018034452A1

WO2018034452A1 - Method for transmitting frame in wireless lan system, and wireless terminal using method

Info

Publication number: WO2018034452A1
Application number: PCT/KR2017/008398
Authority: WO
Inventors: 박은성; 류기선; 조한규; 최진수
Original assignee: 엘지전자 주식회사
Priority date: 2016-08-17
Filing date: 2017-08-03
Publication date: 2018-02-22

Abstract

A method for transmitting a frame to a first wireless terminal comprising a main radio module and wake-up receiver (WUR) module in a wireless LAN system according to one embodiment of the present invention comprises the steps of: a second wireless terminal composing a wake-up packet for activating a main radio module, the wake-up packet comprising address information indicating the first wireless terminal and an operating band indicator indicating an operating band of the main radio module; and the second wireless terminal transmitting the wake-up packet to a WUR module of the first wireless terminal.

Description

Method for transmitting frame in WLAN system and wireless terminal using same

The present disclosure relates to a method for transmitting a frame for low power communication in a WLAN system and a wireless terminal using the same. More particularly, a method for transmitting a wake-up packet including an operation band indicator in a WLAN system and a radio using the same It relates to a terminal.

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 next-generation WLANs, we are interested in scenarios such as wireless office, smart-home, stadium, hot spot, building / apartment and based on the scenario. As a result, there is a discussion about improving system performance in a dense environment with many APs and 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.

An object of the present specification is to provide a method for transmitting a frame with improved performance in a WLAN system for low power communication and a wireless terminal using the same.

In a method of transmitting a frame to a first wireless terminal including a main radio module and a wake-up receiver (WUR) module in a WLAN system according to an embodiment of the present disclosure, a second wireless terminal may be configured to activate a main radio module. Configure a wake-up packet, wherein the wake-up packet includes address information indicating a first wireless terminal and an operating band indicator indicating an operating band of the main radio module. Doing; And transmitting, by the second wireless terminal, the wakeup packet to the WUR module of the first wireless terminal.

According to an embodiment of the present disclosure, a method for transmitting a frame with improved performance in a WLAN system for low power communication and a wireless terminal using the same are provided.

1 is a conceptual diagram illustrating a structure of a WLAN system.

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 shows an internal block diagram of a wireless terminal receiving a wakeup packet.

5 is a conceptual diagram illustrating a method in which a wireless terminal receives a wakeup packet and receives user data.

6 shows an example of a format of a wakeup packet.

7 shows a signal waveform of a wakeup packet.

FIG. 8 is a diagram for describing a procedure of determining power consumption according to a ratio of bit values constituting information in a binary sequence form.

9 is a diagram illustrating a design process of a pulse according to the OOK technique.

10 is a conceptual diagram for explaining a Manchester coding technique.

11 is a diagram illustrating an example of a format of a wakeup packet according to the present embodiment.

12 is a flowchart illustrating a procedure of transmitting a wake-up packet according to the present embodiment.

13 is a flowchart illustrating a procedure for receiving a wakeup packet according to the present embodiment.

14 is a block diagram illustrating a wireless terminal to which an embodiment of the present specification can be applied.

The above-described features and the following detailed description are all exemplary for ease of description and understanding of the present specification. That is, the present specification is not limited to this embodiment and may be embodied in other forms. The following embodiments are merely examples to fully disclose the present specification, and are descriptions to convey the present specification to those skilled in the art. Thus, where there are several methods for implementing the components of the present disclosure, it is necessary to clarify that any of these methods may be implemented in any of the specific or equivalent thereof.

In the present specification, when there is a statement that a configuration includes specific elements, or when a process includes specific steps, it means that other elements or other steps may be further included. That is, the terms used in the present specification are only for describing specific embodiments and are not intended to limit the concept of the present specification. Furthermore, the described examples to aid the understanding of the invention also include their complementary embodiments.

The terminology used herein has the meaning commonly understood by one of ordinary skill in the art to which this specification belongs. Terms commonly used should be interpreted in a consistent sense in the context of the present specification. In addition, terms used in the present specification should not be interpreted in an idealistic or formal sense unless the meaning is clearly defined. Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

1 is a conceptual diagram illustrating a structure of a WLAN system. FIG. 1A shows the structure of an infrastructure network of the Institute of Electrical and Electronic Engineers (IEEE) 802.11.

Referring to FIG. 1A, the WLAN system 10 of FIG. 1A may include at least one basic service set (hereinafter, referred to as 'BSS', 100, 105). The BSS is a set of access points (APs) and stations (STAs) that can successfully synchronize and communicate with each other, and is not a concept indicating a specific area.

For example, the first BSS 100 may include a first AP 110 and one first STA 100-1. The second BSS 105 may include a second AP 130 and one or more STAs 105-1, 105-2.

The infrastructure BSS (100, 105) may include at least one STA, AP (110, 130) providing a distribution service (Distribution Service) and a distribution system (DS, 120) connecting a plurality of APs. have.

The distributed system 120 may connect the plurality of

BSSs

100 and 105 to implement an extended service set 140 which is an extended service set. The ESS 140 may be used as a term indicating one network to which at least one

AP

110 or 130 is connected through the distributed system 120. At least one AP included in one ESS 140 may have the same service set identification (hereinafter, referred to as SSID).

The portal 150 may serve as a bridge for connecting the WLAN network (IEEE 802.11) with another network (for example, 802.X).

In a WLAN having a structure as shown in FIG. 1A, a network between

APs

110 and 130 and a network between

APs

110 and 130 and STAs 100-1, 105-1, and 105-2 may be implemented. Can be.

1B is a conceptual diagram illustrating an independent BSS. Referring to FIG. 1B, the WLAN system 15 of FIG. 1B performs communication by setting a network between STAs without the

APs

110 and 130, unlike FIG. 1A. It may be possible to. A network that performs communication by establishing a network even between STAs without the

APs

110 and 130 is defined as an ad-hoc network or an independent basic service set (BSS).

Referring to FIG. 1B, the IBSS 15 is a BSS operating in an ad-hoc mode. Since IBSS does not contain an AP, there is no centralized management entity. Thus, in the IBSS 15, the STAs 150-1, 150-2, 150-3, 155-4, and 155-5 are managed in a distributed manner.

All STAs 150-1, 150-2, 150-3, 155-4, and 155-5 of the IBSS may be mobile STAs, and access to a distributed system is not allowed. All STAs of the IBSS form a self-contained network.

The STA referred to herein includes a 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. As any functional medium, it can broadly be used to mean both an AP and a non-AP Non-AP Station (STA).

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

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 over a wider bandwidth (eg, 40 MHz, 80 MHz) than the channel bandwidth of 20 MHz may be a structure applying linear scaling to the PPDU structure used in the 20 MHz channel bandwidth.

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.

Referring to FIG. 4, the WLAN system 400 according to the present embodiment may include a first wireless terminal 410 and a second wireless terminal 420.

The first wireless terminal 410 includes a main radio module 411 associated with the main radio (ie, 802.11) and a module including a low-power wake-up receiver ('LP WUR') (hereinafter, WUR). Module 412. The main radio module 411 may transmit user data or receive user data in an active state (ie, an ON state).

The main radio module 411 may be switched to an inactive state (ie, an OFF state) when there is no data (or packet) to be transmitted by the main radio module 411. For example, the main radio module 411 may include a plurality of circuits supporting Wi-Fi, Bluetooth® radio (hereinafter referred to as BT radio) and Bluetooth® Low Energy radio (hereinafter referred to as BLE radio).

Modules (eg, 411, 412) of a wireless terminal in an inactive state (OFF state) may be understood as a deep sleep state. According to the related art, even when the wireless terminal is in a sleep state according to a power save mode, the beacon frame periodically transmitted by the AP may be received.

In contrast, the main radio module 411 in an inactive state (ie, OFF state) cannot receive a beacon frame periodically transmitted by the AP until it is woken by the WUR module 412.

The wireless terminal may receive a frame (or packet) from another wireless terminal based on the main radio module 411 or the WUR module 412 in an active state.

The WUR module 412 may be a receiver for waking the main radio module 411. That is, the WUR module 412 may not include a transmitter. The WUR module 412 may remain active for a duration in which the main radio module 411 is inactive. For example, when a wakeup packet for the main radio module 411 is received, the WUR module 412 may transition the inactive main radio module 411 to the active state.

The low power wake up receiver (LP WUR) included in the WUR module 412 targets a target power consumption of less than 1 mW in the active state. In addition, low power wake-up receivers may use a narrow bandwidth of less than 5 MHz.

In addition, the power consumption by the low power wake-up receiver may be less than 1 Mw. In addition, the target transmission range of the low power wake-up receiver may be the same as the target transmission range of the existing 802.11.

The second wireless terminal 420 according to the present embodiment may transmit user data based on a main radio (ie, 802.11). The second wireless terminal 420 can transmit a wakeup packet for the WUR module 412.

Referring to FIG. 4, the second wireless terminal 420 may not transmit user data or a wakeup packet for the first wireless terminal 410. In this case, the main radio module 411 of the first wireless terminal 410 may be in an inactive state (ie, in an OFF state). The WUR module 412 of the first wireless terminal 410 may be in an active state (ie, in an ON state).

4 and 5, the WLAN system 500 according to the present embodiment may include a first wireless terminal 510 and a second wireless terminal 520. Basic operations of the first wireless terminal 510 of FIG. 5 may be understood through the description of the first wireless terminal 410 of FIG. 4.

Similarly, the basic operation of the second wireless terminal 520 of FIG. 5 may be understood through the description of the second wireless terminal 420 of FIG. 4.

Referring to FIG. 5, when the wakeup packet 521 is received by the WUR module 512 in an active state, the WUR module 512 may transmit data to the main radio module 511 after the wakeup packet 521. The wakeup signal 523 may be transmitted to the main radio module 511 to correctly receive the packet 522.

For example, when the main radio module 511 receives the wake-up signal 523, all of the plurality of circuits (not shown) supporting Wi-Fi, BT radio, and BLE radio included in the main radio module 511 may be provided. It can be activated or only part of it.

As another example, the actual data included in the wakeup packet 521 may be directly transmitted to a memory block (not shown) of the first wireless terminal 510 even when the main radio module 511 is inactive.

As another example, when the wake-up packet 521 includes an IEEE 802.11 MAC frame, the receiving terminal may activate only the MAC processor of the main radio module 511. That is, the receiving terminal may keep the PHY module of the main radio module 511 in an inactive state. The wakeup packet 521 of FIG. 5 will be described in more detail with reference to the following drawings.

The second wireless terminal 520 can be set to transmit the wakeup packet 521 to the first wireless terminal 510. For example, the second wireless terminal 520 may instruct the main radio module 511 of the first wireless terminal 510 to be switched to an active state (ie, an ON state) through the wakeup packet 521. .

6 shows an example of a format of a wakeup packet.

1 to 6, the wakeup packet 600 may include one or more legacy preambles 610. In addition, the wakeup packet 600 may include a payload 620 after the legacy preamble 610. The payload 620 may be modulated by a simple modulation scheme (eg, On-Off Keying (OOK) modulation scheme). Payloads can also be transmitted using small bandwidths.

1 through 6, a transmitting terminal (eg, 520) may be configured to generate and / or transmit

wakeup packets

521, 600. The first wireless terminal (eg, 510) can be configured to process the received wakeup packet 521.

For example, the wakeup packet 600 may include a legacy preamble 610 or any other preamble (not shown) defined in the existing IEEE 802.11 standard. The wakeup packet 600 may include one packet symbol 615 after the legacy preamble 610. In addition, the wakeup packet 600 may include a payload 620.

The legacy preamble 610 may be provided for coexistence with the legacy STA. In the legacy preamble 610 for coexistence, an L-SIG field for protecting a packet may be used.

For example, the 802.11 STA may detect the beginning of a packet through the L-STF field in the legacy preamble 610. The STA may detect an end portion of the 802.11 packet through the L-SIG field in the legacy preamble 610.

By adding one symbol 615 modulated according to the BiPhase Shift Keying (BPSK) technique after the L-SIG of FIG. 6, a false alarm of the 802.11n terminal may be reduced. One symbol modulated according to the BPSK technique (eg, 4us in length) may also have a 20MHz bandwidth like the legacy part.

The legacy preamble 610 may be understood as a field for a third party legacy STA (STA that does not include the LP-WUR). In other words, the legacy preamble 610 may not be decoded by the LP-WUR.

Payload 620 includes a wake-up preamble field 621, a MAC header field 623, a frame body field 625, and a Frame Check Sequence (FCS) field 627. can do.

The wakeup preamble field 621 may include a sequence for identifying the wakeup packet 600. For example, the wakeup preamble field 621 may include a pseudo random noise sequence (PN).

The MAC header field 624 may include address information (or an identifier of a receiving apparatus) indicating the first wireless terminal receiving the wakeup packet 600. The frame body field 626 may include other information of the wakeup packet 600.

The frame body 626 may include length information or size information of the payload. Referring to FIG. 6, the length information of the payload may be calculated based on length LENGTH information and MCS information included in the legacy preamble 610.

The FCS field 628 may include a Cyclic Redundancy Check (CRC) value for error correction. For example, the FCS field 628 may include a CRC-8 value or a CRC-16 value for the MAC header field 623 and the frame body 625.

7 shows a signal waveform of a wakeup packet.

Referring to FIG. 7, the wakeup packet 700 may include payloads 722 and 724 modulated based on a legacy preamble (802.11 preamble, 710) and an On-Off Keying (OOK) scheme. That is, the wakeup packet according to the present embodiment may be understood as a form in which a legacy preamble and a new LP-WUR signal waveform coexist.

In the legacy preamble 710 of FIG. 7, the OOK technique may not be applied. As mentioned above, payloads 722 and 724 may be modulated based on the OOK technique. However, the wakeup preamble 722 included in the payloads 722 and 724 may be modulated based on another modulation technique.

As an example, it may be assumed that the legacy preamble 710 is transmitted on a channel bandwidth of 20 MHz to which 64 FFTs are applied. In this case, payloads 722, 724 may be transmitted on a channel bandwidth of about 4.06 MHz.

Referring to FIG. 8, information in the form of a binary sequence having '1' or '0' as a bit value may be represented. Communication based on the OOK modulation scheme may be performed based on the bit values of the binary sequence information.

For example, when the light emitting diode is used for visible light communication, when the bit value constituting the binary sequence information is '1', the light emitting diode is turned on, and when the bit value is '0', the light emitting diode is turned off. (off) can be turned off.

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 may be provided. For example, information in the form of a binary sequence having a value of '1001101011' may be provided.

As described above, when the bit value is '1', when the transmitting terminal is turned on and when the bit value is '0', when the transmitting terminal is turned off, 6 bit values of the above 10 bit values are applied. The corresponding symbol is turned on.

Since the wake-up receiver WUR according to the present embodiment is included in the receiving terminal, the transmission power of the transmitting terminal may not be greatly considered. The reason why the OOK technique is used in the present embodiment is because power consumption in the decoding procedure of the received signal is very small.

Until the decoding process is performed, there may be no significant difference in power consumption between power consumption in the main radio and power consumption in the WUR. However, when performing the decoding procedure, a large difference in power consumption may occur between power consumption in the main radio and power consumption in the WUR. 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 is a diagram illustrating a design process of a pulse according to the OOK technique. The OFDM transmitter of 802.11 can be used to generate pulses according to the OOK technique. The OFDM transmitter of 802.11 can generate 64 sequences by applying 64-point IFFT as in 802.11.

An OFDM transmitter of 802.11 may transmit a payload of a wakeup packet modulated according to the OOK technique. For example, the OOK technique may be applied to the ON-signal of the wakeup packet for low power communication. In this case, the on signal may be a signal having an actual power value.

In addition, the OOK technique may be applied for the OFF-signal of the wakeup packet. In this case, the off signal may be a signal having no actual power value.

That is, the off signal may be understood as a signal that is not actually transmitted for the case where a signal is not generated by using the transmitter. Thus, the off signal may not be considered in the configuration of the wakeup packet.

For example, according to the OOK technique, information (bit) 1 may be an on signal and information (bit) 0 may be an off signal. As another example, according to the Manchester coding scheme, 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.

As another example, according to the Manchester coding scheme, information 1 may indicate a transition from an on signal to an off signal, and information 0 may indicate a transition from an off signal to an on signal. A detailed description of the Manchester coding scheme will be given later.

Referring to the frequency domain graph 920 of FIG. 9, an OFDM transmitter of 802.11 may apply a sequence based on 13 consecutive subcarriers selected from a reference 20 MHz band.

Referring to FIG. 9, 13 subcarriers located among the plurality of subcarriers in the 20 MHz band may be selected as samples. That is, among the 64 subcarriers, a subcarrier whose subcarrier index is from -6 to +6 may be selected. In this case, subcarrier index 0 may be nulled to the DC subcarrier.

That is, a specific sequence is set for the 13 subcarriers selected as samples, and all of the subcarriers (subcarrier indexes -32 to -7 and subcarrier indexes +7 to +31) except for the 13 subcarriers are all '0'. 'Can be set.

For example, the subcarrier spacing is 312.5 KHz, and the 13 subcarriers may be set to have a channel bandwidth of about 4.06 MHz. In other words, it can be seen that power exists only for 4.06 MHz in the 20 MHz band in the frequency domain.

By using the pulse according to the OOK technique, the power is concentrated in a specific band, so that the signal to noise ratio (SNR) can be increased, and the power consumption for conversion in 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.

Referring to the time domain graph 910 of FIG. 9, an OFDM transmitter of 802.11 may generate one on-signal in the time domain by performing a 64-point IFFT on 13 subcarriers and inserting a CP.

One bit may be allocated for one on-signal. That is, a sequence consisting of 13 subcarriers may correspond to 1 bit. When the IFFT is performed, 3.2us of symbol may be generated, and if CP (Cyclic Prefix, 0.8us) is included, one symbol having a total length of 4us may be generated. That is, one bit indicating one on signal may be loaded as one symbol.

In addition, the OFDM transmitter of 802.11 may not transmit the off signal at all.

According to the above-described embodiment, the receiver may decode the received packet with the minimum power using an envelope detector. For example, a basic data rate for one information may be 125 Kbps (8us) or 62.5 Kbps (16us).

Generalizing the contents of FIG. 9, 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 is the number of subcarriers used to transmit a signal and may correspond to the bandwidth of a pulse according to the OOK technique.

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 a conceptual diagram for explaining a Manchester coding technique.

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, the Manchester coding technique refers to a method of converting data from '1' to '01', '0' to '10', '1' to '10', and '0' to '01'. Referring to Table 1, an example is shown in which data is converted to '10' and '0' to '01' using Manchester coding.

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

Manchester coding techniques may be used by the transmitting device to transmit data. Subsequently, the receiving device may read the data a little later based on the transition point transitioning from 1 → 0 or 0 → 1 to recover the data.

The clock is recovered by recognizing the transition point of 1 → 0 or 0 → 1 as the transition point of the clock. 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', and the signal representing the bit string to be transmitted using the Manchester coding scheme may be '0110100101011001'. Subsequently, the clock reproduced by the receiver may recognize the transition point of the signal expressed by the Manchester coding technique as the transition point of the clock. The receiving side can recover data by using the reproduction clock obtained in the above process.

Using this Manchester coding scheme, synchronized bidirectional communication may be performed using only a data transmission channel without a separate clock. That is, by using only the data transmission channel, the TXD pin can be used for data transmission, and the RXD pin can be used for data reception.

As a method of decoding a wake-up packet in a transmitter, there may be a non-coherent detection method and two coherent detection methods.

For example, the non-coherent detection method is a method in which the phase relationship between the signals of the transmitter and the receiver is not fixed. Thus, the receiver does not need to measure and adjust the phase of the received signal.

As another example, a coherent detection method is a method in which phases are matched between signals of a transmitter and a receiver. Therefore, the receiving apparatus needs to measure and adjust the phase of the received signal.

The receiving device according to the present embodiment may include the aforementioned low power wake-up receiver (ie, wake-up receiver, WUR). The wakeup receiver (WUR) may decode a packet (wakeup packet) generated according to a OOK modulation scheme using an envelope detector to reduce power consumption by the terminal.

The envelope detector may decode the received packet (wakeup packet) based on the power or magnitude of the received signal. The receiver may decode a symbol to which the OOK is applied based on a preset threshold and power or magnitude measured by the envelope detector.

For example, when the threshold and the power or magnitude measured by the envelope detector are greater than or equal to the threshold, it may be determined as information 1, and if less than the threshold, it may be determined as information 0.

1 to 11, the wireless terminal according to the present embodiment may use the 2.4 GHz band and the 5 GHz band as operating bands for wireless communication. In addition, the wireless terminal may use a band below 1 GHz (ie, a sub 1 GHz band) and a 60 GHz band as an operating band for wireless communication.

The wireless terminal according to the present embodiment may perform communication based on any one of a plurality of frequency bands (eg, 1 GHz or less band, 2.4 GHz band, 5 GHz band, and 60 GHz band).

The wireless terminal according to the present embodiment may use a main radio module (eg, 511 of FIG. 5) that can use all of a plurality of frequency bands, and a WUR module (eg, 512 of FIG. 5) that can use only a part of the plurality of frequency bands. It may include.

If there is user data to be transmitted by the wireless terminal according to the present embodiment, the main radio module (eg, 511 of FIG. 5) may be in an active state capable of communicating with another wireless terminal.

If there is no user data to be transmitted by the wireless terminal according to the present embodiment, the main radio module (eg, 511 of FIG. 5) may be in an inactive state in which communication with another wireless terminal cannot be performed.

The wireless terminal in the sleep state of the conventional PS (power saving) mode may receive a beacon frame periodically transmitted from the AP. In contrast, the wireless terminal in the inactive state according to the present embodiment may not receive a beacon frame periodically transmitted from the AP.

In addition, when the main radio module (eg, 511 of FIG. 5) according to the present embodiment is inactive, the WUR module (eg, 512 of FIG. 5) according to the present embodiment may receive a wake-up packet from another wireless terminal. It can remain active.

When the WUR module (eg, 512 of FIG. 5) according to the present embodiment operates in some operating bands, the WUR module includes an operating band included in an operating band indication (OBI) field 1124. The indicator may be configured to transmit a signal (eg, a wakeup signal of FIG. 5) for activating the main radio module (eg, 512 of FIG. 5).

For example, the wakeup signal of FIG. 5 may be implemented based on primitive information inside the first wireless terminal 510.

The main radio module (for example, 511 of FIG. 5) according to the present embodiment may include a plurality of frequency bands (for example, the wakeup signal of FIG. 5) received from a WUR module (for example, 512 of FIG. 5). The frequency band of any one of the band below 1 GHz, the 2.4 GHz band, the 5 GHz band, and the 60 GHz band may be determined as an operating band.

Subsequently, the main radio module (eg, 511 of FIG. 5) according to the present embodiment may communicate with another wireless terminal (eg, 520 of FIG. 5) using the determined operating band.

1 through 11, the wakeup packet 1100 of FIG. 11 may include one or more legacy preambles 1110, packet symbols 1115, and payload 1120. One or more legacy preambles 1110 and packet symbols 1115 of FIG. 11 may be understood through descriptions associated with legacy preambles 610 and packet symbols 615 of FIG. 6 above.

The payload 1120 of FIG. 11 includes a wakeup preamble field 1121, a MAC header field 1123, an operating band indication (OBI) field 1124, a frame body field 1125, and a Frame Check Sequence (FCS) field ( 1127). The payload 1120 of FIG. 11 may be understood as a modulated field according to the OOK technique.

The remaining

fields

1121, 1123, 1125, and 1127 of the payload 1120 except for the operating band indication (OBI) field 1124 of FIG. 11 are the wake-up preamble field 621 and the MAC header field 623 of FIG. 6. ), Frame body field 625 and FCS field 627 can be understood through the description.

The operating band indication (OBI) field 1124 of FIG. 11 may be demodulated only by the wireless terminal indicated by the address information included in the MAC header field 1123.

The operating band indicator (OBI) field 1124 of FIG. 11 may include an operating band indicator. According to the present embodiment, the wireless terminal having obtained the information on the operating band indicator may wake up the main radio module according to the operating band indicator.

For the operating band indicator according to the present embodiment, 2 bits may be allocated as shown in Table 2 below.

Referring to Table 2, as an example, if '00' is indicated by the operating band indicator included in the wake-up packet 1100 received by the wireless terminal, the WUR module (for example, 512 of FIG. 5) of the wireless terminal is main. A signal (eg, a wakeup signal of FIG. 5) for activating a radio module (eg, 512 of FIG. 5) in the Sub 1 GHz band may be transmitted to a main radio module (eg, 512 of FIG. 5).

For example, when '01' is indicated by the operating band indicator included in the wakeup packet 1100 received by the wireless terminal, the WUR module (for example, 512 of FIG. 5) of the wireless terminal is the main radio module (for example, FIG. A signal activating 512 of 5 in the 2.4 GHz band (eg, the wakeup signal of FIG. 5) may be transmitted to the main radio module (eg, 512 of FIG. 5).

For example, when '01' is indicated by the operating band indicator included in the wakeup packet 1100 received by the wireless terminal, the WUR module (for example, 512 of FIG. 5) of the wireless terminal is the main radio module (for example, FIG. A signal for activating 512 of 5 in the 5 GHz band (for example, the wakeup signal of FIG. 5) may be transmitted to the main radio module (for example, 512 of FIG. 5).

For example, when '01' is indicated by the operating band indicator included in the wakeup packet 1100 received by the wireless terminal, the WUR module (for example, 512 of FIG. 5) of the wireless terminal is the main radio module (for example, FIG. A signal for activating 512 of 5 in the 60 GHz band (for example, the wakeup signal of FIG. 5) may be transmitted to the main radio module (for example, 512 of FIG. 5).

As another example, when the main radio module of the wireless terminal (for example, 512 of FIG. 5) communicates with another wireless terminal based on a 2.4 GHz band or a 5 GHz band, the following operation band indicator according to the present embodiment may be used. One bit may be allocated as shown in Table 3.

Referring to Table 3, as an example, if '0' is indicated by the operating band indicator included in the wakeup packet 1100 received by the wireless terminal, the WUR module (for example, 512 of FIG. 5) of the wireless terminal is main. A signal (eg, a wake-up signal of FIG. 5) for activating a radio module (eg, 512 of FIG. 5) in a 2.4 GHz band may be transmitted to the main radio module (eg, 512 of FIG. 5).

For example, when '1' is indicated by the operating band indicator included in the wakeup packet 1100 received by the wireless terminal, the WUR module (for example, 512 of FIG. 5) of the wireless terminal is the main radio module (for example, FIG. 5). A signal for activating 512 of 5 in the 5 GHz band (for example, the wakeup signal of FIG. 5) may be transmitted to the main radio module (for example, 512 of FIG. 5).

As another example, when the main radio module of the wireless terminal (for example, 512 of FIG. 5) communicates with another wireless terminal based on a 2.4 GHz band or a 5 GHz band, the main radio module of the wireless terminal performs the following operation band indicator according to the present embodiment. As shown in Table 4, 1 bit may be allocated.

Referring to Table 4, as an example, when '0' is indicated by the operating band indicator included in the wakeup packet 1100 received by the wireless terminal, the WUR module (for example, 512 of FIG. 5) of the wireless terminal is WUR. Main signal (eg, wake-up signal of FIG. 5) for activating the main radio module (eg, 512 of FIG. 5) in the same frequency band as the operating band (eg, 2.4 GHz) of the module (eg, 512 of FIG. 5). And transmit to a radio module (eg, 512 of FIG. 5).

For example, when '1' is indicated by the operating band indicator included in the wakeup packet 1100 received by the wireless terminal, the WUR module (for example, 512 of FIG. 5) of the wireless terminal is a WUR module (for example, FIG. 5). The signal for activating the main radio module (e.g., 512 of FIG. 5) to a different frequency band (e.g., 5 GHz) from an operating band (e.g., 2.4 GHz) of 512). And transmit to a radio module (eg, 512 of FIG. 5).

Tables 2 to 4 are merely examples for convenience of description, and it will be understood that the present specification is not limited thereto. In other words, the mapping relationship between elements and operating bands of Tables 2 to 4 may vary.

1 to 12, in step S1210, a wake-up packet for activating the main radio module (511 of FIG. 5) of the first wireless terminal (eg, 510 of FIG. 5) may be used. 521 may be configured by a second wireless terminal (eg, 520).

For example, the wakeup packet (eg, 521 of FIG. 5) may include address information indicating a first wireless terminal (eg, 510 of FIG. 5) and an operating band of the main radio module (511 of FIG. 5). It may include an operating band indicator (operating band indicator) indicating.

The first wireless terminal (eg, 510 of FIG. 5) according to the present embodiment may include a main radio module (eg, 511 of FIG. 5) and a wake-up receiver (eg, 512 of FIG. 5). .

For example, the main radio module (eg, 511 of FIG. 5) may be configured to include a first receiver and a first wireless terminal (eg, FIG. 5 of FIG. 5) for receiving first user data from another wireless terminal (eg, 520 of FIG. 5). A first transmitter for second user data to be transmitted by 510.

The WUR module (eg, 512 of FIG. 5) may include a second receiver for receiving a wakeup packet from another wireless terminal (eg, 520 of FIG. 5).

The main radio module (eg, 511 of FIG. 5) included in the first wireless terminal (eg, 510 of FIG. 5) according to the present embodiment may be in an active state or an inactive state.

For example, if there is user data to be transmitted by the first wireless terminal (eg, 510 of FIG. 5), the main radio module (eg, 511 of FIG. 5) may be connected to another wireless terminal (eg, 520 of FIG. 5). It may be in an active state capable of communicating.

If there is no user data to be transmitted by the first wireless terminal (eg, 510 of FIG. 5), the main radio module (eg, 511 of FIG. 5) may communicate with another wireless terminal (520 of FIG. 5). Can be in an inactive state.

The WUR module (eg, 512 of FIG. 5) included in the first wireless terminal according to the present embodiment may be in an active state or an inactive state. For example, if the main radio module (eg, 511 of FIG. 5) is inactive, the WUR module (eg, 512 of FIG. 5) may communicate with a second wireless terminal (eg, 520 of FIG. 5). Which may be in an active state (ie, capable of receiving a wakeup packet from a second wireless terminal).

The wakeup packet according to the present embodiment may include a payload field for a WUR module (eg, 512 of FIG. 5). For example, the payload field may be modulated according to an on-off keying (OOK) technique.

In addition, the payload field may include address information and an operating band indicator. For example, the address information may be set to indicate the first wireless terminal (eg, 510 of FIG. 5) according to a unicast technique.

For example, the operating band indicator may be demodulated by the first wireless terminal (eg, 510 of FIG. 5) indicated by the address information.

In addition, the operating band indicator is an operating band for the main radio module (eg, 511 of FIG. 5) of the first wireless terminal (eg, 510 of FIG. 5) based on 2 bits. , 5 GHz band and 60 GHz band.

In addition, if the WUR module (eg, 512 of FIG. 5) operates in one of the 2.4 GHz band and the 5 GHz band, the operating band indicator may be set to indicate either the 2.4 GHz band or the 5 GHz band. .

In addition, if the WUR module (for example, 512 of FIG. 5) operates in one of the 2.4 GHz band and the 5 GHz band, the operating band indicator is for indicating the same operating band as the WUR module (for example, 512 of FIG. 5). One of the first value and the second value for indicating an operating band different from the WUR module (eg, 512 of FIG. 5) may be set.

In operation S1220, the second wireless terminal (eg, 520 of FIG. 5) may transmit a wakeup packet to the first wireless terminal (eg, 510 of FIG. 5) that is the receiving terminal.

1 to 13, in step S1310, a first wireless terminal (eg, 510 of FIG. 5), which is a receiving terminal, may be configured based on a second wireless terminal (eg, 512 of FIG. 5) based on an active WUR module (eg, 512 of FIG. 5). For example, a wakeup packet (eg, 521 of FIG. 5) may be received from 520 of FIG. 5.

In operation S1320, the first wireless terminal (eg, 510 of FIG. 5) may determine whether the first wireless terminal is indicated by the address information included in the wakeup packet. For example, the address information may be set to indicate any one wireless terminal according to the unicast technique.

If the first wireless terminal (eg, 510) is not indicated by the address information, the first wireless terminal (eg, 510 of FIG. 5) may not demodulate the remaining information of the wakeup packet and the procedure may be terminated. have.

If the first wireless terminal (eg, 510 of FIG. 5) is indicated by the address information, it is possible to demodulate the remaining information (ie, the operating band indicator) of the wakeup packet. If the first wireless terminal (eg, 510 of FIG. 5) is indicated by the address information, step S1330 may be performed.

In operation S1330, the first wireless terminal (eg, 510 of FIG. 5) is a main radio module (eg, in an inactive state of the first wireless terminal (eg, 510 of FIG. 5) in the operating band indicated by the operating band indicator. 5 may be switched to an active state in which communication with another wireless terminal (eg, 520 of FIG. 5) is possible.

Referring to FIG. 14, the wireless terminal may be an STA or an AP or a non-AP STA that may implement the above-described embodiment. The wireless terminal may correspond to the above-described user or may correspond to a transmitting terminal for transmitting a signal to the user.

The AP 1400 includes a processor 1410, a memory 1420, and an RF unit 1430.

The RF unit 1430 may be connected to the processor 1410 to transmit / receive a radio signal.

The processor 1410 may implement the functions, processes, and / or methods proposed herein. For example, the processor 1410 may perform an operation according to the above-described exemplary embodiment. The processor 1410 may perform an operation of the AP disclosed in the present embodiment of FIGS. 1 to 13.

The non-AP STA 1450 may include a processor 1460, a memory 1470, and an RF unit 1480.

The RF unit 1480 may be connected to the processor 1460 to transmit / receive a radio signal.

The processor 1460 may implement the functions, processes, and / or methods proposed in the present embodiment. For example, the processor 1460 may be implemented to perform the non-AP STA operation according to the present embodiment described above. The processor 1460 may perform an operation of the non-AP STA disclosed in this embodiment of FIGS. 1 to 13.

Processors

1410 and 1460 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, data processing devices, and / or converters for interconverting baseband signals and wireless signals. The

memories

1420 and 1470 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices. The

RF unit

1430 and 1480 may include one or more antennas for transmitting and / or receiving a radio signal.

When the embodiment of the present specification is implemented in software, the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function. The module may be stored in the

memories

1420 and 1470 and executed by the

processors

1410 and 1460. The

memories

1420 and 1470 may be inside or outside the

processors

1410 and 1460, and may be connected to the

processors

1410 and 1460 by various well-known means.

In the detailed description of the present specification, specific embodiments have been described, but various modifications are possible without departing from the scope of the present specification. Therefore, the scope of the present specification should not be limited to the above-described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims of the present invention.

Claims

A method for transmitting a frame to a first wireless terminal including a main radio module and a wake-up receiver (WUR) module in a wireless LAN system,

The second wireless terminal configures a wake-up packet for activating the main radio module, wherein the wake-up packet includes address information indicating the first wireless terminal and an operating band of the main radio module. an operating band indicator indicating an operating band; And

Sending, by the second wireless terminal, the wakeup packet to the WUR module of the first wireless terminal.
According to claim 1,

If there is user data to be transmitted by the first wireless terminal, the main radio module is in an active state capable of communicating with the second wireless terminal,

If there is no user data to be transmitted by the first wireless terminal, the main radio module is in an inactive state that cannot communicate with the second wireless terminal,

If the main radio module is in the inactive state, the WUR module is in the active state.
According to claim 1,

The main radio module includes a first receiver for first user data to be received from the second wireless terminal and a first transmitter for second user data to be transmitted by the first wireless terminal,

And the WUR module includes a second receiver for receiving the wakeup packet.
The method of claim 3, wherein

And when the wakeup packet is received by the WUR module, the WUR module is configured to send a wakeup signal to the main radio module to activate the main radio module according to the operating band indicator.
According to claim 1,

The wakeup packet includes a payload field for the WUR module,

The payload field is modulated according to the on-off keying (OOK) technique,

And the address information and the operating band indicator are information included in the payload field.
According to claim 1,

The address information is set to indicate the first wireless terminal according to a unicast technique;

The operating band indicator is demodulated by the first wireless terminal indicated by the address information.
According to claim 1,

The operating band indicator is set to indicate any one of a sub 1 GHz band, a 2.4 GHz band, a 5 GHz band, and a 60 GHz band as an operating band for the main radio module based on 2 bits.
According to claim 1,

The WUR module operates in any one of a 2.4 GHz band and a 5 GHz band,

The operating band indicator is set to indicate either the 2.4 GHz band or the 5 GHz band.
According to claim 1,

The WUR module operates in any one of a 2.4 GHz band and a 5 GHz band,

And the operating band indicator is set to either a first value for indicating the same operating band as the WUR module and a second value for indicating a different operating band than the WUR module.
A second wireless terminal using a method for transmitting a frame to a first wireless terminal including a main radio module and a wake-up receiver (WUR) module in a wireless LAN system, wherein the second wireless terminal includes:

A transceiver for transmitting and receiving a radio signal; And

A processor coupled to the transceiver, wherein the processor includes:

And a wake-up packet for activating the main radio module, wherein the wake-up packet includes address information indicating the first radio terminal and an operating band of the main radio module. Including an operating band indicator (operating band indicator),

And transmit the wakeup packet to the WUR module of the first wireless terminal.