WO2018056674A1 - Method for managing power of wireless terminal in wireless lan system and wireless terminal using same - Google Patents

Abstract

A method for managing power of a wireless terminal in a wireless LAN system according to an embodiment of the present specification comprises the steps of: a second wireless terminal transmitting a wake-up packet, which indicates a main radio module to enter into an activated state, to a first wireless terminal comprising the main radio module, which is in a deactivated state, and a WUR module which is for waking up the main radio module; the second wireless terminal receiving, by means of the first wireless terminal, a first response packet for notifying the successful reception of the wake-up packet; and the second wireless terminal transmitting a data packet to the first wireless terminal after the reception of the first response packet, wherein the wake-up packet is transmitted on the basis of an EDCA parameter set which is the same as the data packet to be transmitted by means of the second wireless terminal, and the wake-up packet comprises a payload modulated by means of an OOK technique for the WUR module.

Description

Method for managing power of wireless terminal in wireless LAN system and wireless terminal using same

The present disclosure relates to low power wireless communication in a WLAN system, and more particularly, to a method for managing power of a wireless terminal in a WLAN system and a wireless terminal using the same.

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 managing the power of a wireless terminal in a wireless LAN system for low power wireless communication and a wireless terminal using the same.

Method for managing the power of a wireless terminal in a wireless LAN system according to an embodiment of the present disclosure, a first wireless terminal comprising a main radio module in the inactive state and a WUR module for waking the main radio module, the second The wireless terminal transmits a wakeup packet instructing the main radio module to enter an activated state, wherein the wakeup packet is transmitted based on the same EDCA parameter set as the data packet to be transmitted by the second wireless terminal, The wakeup packet includes a payload modulated according to the OOK technique for the WUR module, and; Receiving, by the second wireless terminal, a first reply packet notifying the successful reception of the wakeup packet to the first wireless terminal; And transmitting, by the second wireless terminal, the data packet to the first wireless terminal after reception of the first reply packet.

According to an embodiment of the present disclosure, a method for managing power of a wireless terminal in a wireless LAN system for low power wireless 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 view illustrating an EDCA-based channel access method in a WLAN system.

11 is a conceptual diagram illustrating a backoff procedure according to EDCA.

12 is a view for explaining a frame transmission procedure in a WLAN system.

13 shows a block diagram of a wireless terminal for a procedure of transmitting a wake-up packet in a WLAN system.

14 is a diagram for describing a method for managing power of a wireless terminal in a wireless LAN system according to the present embodiment.

15 to 17 are diagrams for describing a method for managing power of a wireless terminal by reflecting a turn-on delay in a wireless LAN system according to the present embodiment.

18 is a diagram for describing a method for managing power of a wireless terminal by reflecting a turn-on delay in a wireless LAN system according to another exemplary embodiment.

19 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.

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

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 activated state (ie, an ON state).

When there is no data (or packet) to be transmitted by the main radio module 411, the first radio terminal 410 may control the main radio module 411 to enter an inactive state (ie, an OFF state). 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).

According to the related art, a wireless terminal operating based on a power save mode may operate in an active state or a sleep state.

For example, a wireless terminal in an activated state can receive all frames from another wireless terminal. In addition, the wireless terminal in the sleep state may receive a specific type of frame (eg, a beacon frame transmitted periodically) transmitted by another wireless terminal (eg, AP).

It is assumed that the wireless terminal referred to herein can operate the main radio module in an activated state or in an inactive state.

A wireless terminal comprising a main radio module 411 in an inactive state (i.e., in an OFF state) may receive a frame transmitted by another wireless terminal (e.g., AP) until the main radio module is woken up by the WUR module 412. For example, it is not possible to receive an 802.11 type PPDU).

For example, a wireless terminal including the main radio module 411 in an inactive state (ie, in an OFF state) may not receive a beacon frame periodically transmitted by the AP.

That is, it may be understood that the wireless terminal including the main radio module (eg, 411) in the inactive state (ie, the OFF state) according to the present embodiment is in a deep sleep state.

In addition, a wireless terminal that includes a main radio module 411 that is in an active state (ie, in an ON state) may receive a frame (eg, an 802.11 type PPDU) transmitted by another wireless terminal (eg, an AP). have.

In addition, it is assumed that the wireless terminal referred to herein can operate the WUR module in a turn-off state or in a turn-on state.

A wireless terminal that includes a WUR module 412 in a turn-on state can only receive certain types of frames transmitted by other wireless terminals. In this case, a specific type of frame may be understood as a frame modulated by an on-off keying (OOK) modulation scheme described below with reference to FIG. 5.

A wireless terminal that includes a WUR module 412 in a turn-off state cannot receive certain types of frames transmitted by other wireless terminals.

In this specification, to indicate the ON state of a specific module included in the wireless terminal, the terms for the activation state and the turn-on state may be used interchangeably. In the same context, the terms deactivation state and turn-off state may be used interchangeably to indicate an OFF state of a particular module included in the wireless terminal.

The wireless terminal according to the present embodiment may receive a frame (or packet) from another wireless terminal based on the main radio module 411 or the WUR module 412 in an activated 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 turned on for a duration in which the main radio module 411 is inactive.

For example, when a wake-up packet (WUP) for the main radio module 411 is received, the first radio terminal 410 may be configured to have a main radio module 411 in an inactive state. It can be controlled to enter the activation 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 an 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 (WUP) for the WUR module 412.

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

5 is a conceptual diagram illustrating a method for a wireless terminal to receive a wakeup packet and a data packet.

4 and 5, the WLAN system 500 according to the present embodiment may include a first wireless terminal 510 corresponding to the receiving terminal and a second wireless terminal 520 corresponding to the transmitting terminal. have. 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, the wakeup signal 523 may be implemented based on primitive information inside the first wireless terminal 510.

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 receiving terminal even if the main radio module 511 is in an inactive state.

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 maintain 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 instructs the main radio module 511 of the first wireless terminal 510 to enter an activated state (ie, an ON state) according to the wakeup packet 521. can do.

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, an On-Off Keying (OOK) modulation scheme). The wakeup packet 600 including the payload may be relatively small. It may be transmitted based on bandwidth.

1 through 6, a second wireless 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.

In order to reduce false alarm of the 802.11n terminal, a modulated symbol 615 may be added after the L-SIG of FIG. 6. One symbol 615 may be modulated according to a BiPhase Shift Keying (BPSK) technique. One symbol 615 may have a length of 4 us. One symbol 615 may have a 20 MHz bandwidth like a 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 a receiving 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 WUP 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 according to the OOK technique. However, the wakeup preamble 722 included in the payloads 722 and 724 may be modulated according to another modulation technique.

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

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.

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 procedure is performed, there may be no significant difference between the power consumed by the main radio and the power consumed by the WUR. However, as the decoding procedure is performed by the receiving terminal, a large difference may occur between power consumed by the main radio module and power consumed by the WUR module. 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 wireless terminal according to the present embodiment may use an existing 802.11 OFDM transmitter to generate a pulse according to the OOK technique. The existing 802.11 OFDM transmitter can generate a sequence having 64 bits by applying a 64-point IFFT.

1 to 9, the wireless terminal according to the present embodiment may transmit a payload of a wakeup packet (WUP) modulated according to the OOK technique. The payload (eg, 620 of FIG. 6) according to the present embodiment may be implemented based on an ON-signal and an OFF-signal.

The OOK technique may be applied to the ON-signal included in the payload of the wakeup packet WUP (eg, 620 of FIG. 6). In this case, the on signal may be a signal having an actual power value.

Referring to the frequency domain graph 920, the ON signal included in the payload (eg, 620 of FIG. 6) is N2 among N1 subcarriers (N1 is a natural number) corresponding to the channel band of the wakeup packet (WUP). Can be obtained by performing IFFT on the subcarriers N2 is a natural number. In addition, a predetermined sequence may be applied to the N2 subcarriers.

For example, the channel band of the wakeup packet WUP may be 20 MHz. The N1 subcarriers may be 64 subcarriers, and the N2 subcarriers may be 13 consecutive subcarriers (921 of FIG. 9). The subcarrier interval applied to the wakeup packet (WUP) may be 312.5 kHz.

The OOK technique may be applied for the OFF-signal included in the payload (eg, 620 of FIG. 6) of the wakeup packet WUP. The off signal may be a signal that does not have an actual power value. That is, the off signal may not be considered in the configuration of the wakeup packet (WUP).

The ON signal included in the payload (620 of FIG. 6) of the wakeup packet WUP is determined as a 1-bit ON signal (ie, '1') by the WUR module (eg, 512 of FIG. 5) That is, demodulation). Similarly, the off signal included in the payload may be determined (ie, demodulated) as a 1-bit off signal (ie, '0') by the WUR module (eg, 512 of FIG. 5).

A specific sequence may be preset for the subcarrier set 921 of FIG. 9. In this case, the preset sequence may be a 13-bit sequence. For example, a coefficient corresponding to the DC subcarrier in the 13-bit sequence may be '0', and the remaining coefficients may be set to '1' or '-1'.

Referring to the frequency domain graph 920, the subcarrier set 921 may correspond to a subcarrier having a subcarrier index of '-6' to '+6'.

For example, a coefficient corresponding to a subcarrier whose subcarrier indices are '-6' to '-1' in the 13-bit sequence may be set to '1' or '-1'. A coefficient corresponding to a subcarrier whose subcarrier indices are '1' to '6' in the 13-bit sequence may be set to '1' or '-1'.

For example, a subcarrier whose subcarrier index is '0' in a 13-bit sequence may be nulled. The coefficients of the remaining subcarriers (subcarrier indexes '-32' to '-7' and subcarrier indexes '+7' to '+31') except for the subcarrier set 921 are all set to '0'. Can be.

The subcarrier set 921 corresponding to 13 consecutive subcarriers may be set to have a channel bandwidth of about 4.06 MHz. That is, power by signals may be concentrated at 4.06 MHz in the 20 MHz band for the wakeup packet (WUP).

When the pulse according to the OOK technique is used according to the present embodiment, the power is concentrated in a specific band, so that the signal to noise ratio (SNR) may be increased, and the power consumption for conversion in the AC / DC converter of the receiver may be reduced. There is an advantage that it can. Since the sampling frequency band is reduced to 4.06 MHz, power consumption by the wireless terminal can be reduced.

According to the embodiment of the present invention, an OFDM transmitter of 802.11 may have N2 (e.g., 13 consecutive) subs of N1 (e.g., 64) subcarriers corresponding to the channel band (e.g., 20 MHz band) of the wake-up packet. IFFT (eg, 64-point IFFT) may be performed on the carrier.

In this case, a predetermined sequence may be applied to the N2 subcarriers. Accordingly, one on-signal may be generated in the time domain. One bit information corresponding to one on signal may be transmitted through one symbol.

For example, when a 64-point IFFT is performed, a symbol having a 3.2us length corresponding to the subcarrier set 921 may be generated. In addition, when CP (Cyclic Prefix, 0.8us) is added to a symbol having a 3.2us length corresponding to the subcarrier set 921, one symbol having a total length of 4us as shown in the time domain graph 910 of FIG. Can be generated.

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

According to the present embodiment, a wireless terminal (eg, 510 of FIG. 5) including a WUR module (eg, 512 of FIG. 5) demodulates a received packet based on an envelope detector that extracts an envelope of the received signal. (demodulate)

For example, the WUR module (eg, 512 of FIG. 5) according to the present embodiment may compare a power level of a received signal obtained through an envelope of the received signal with a preset threshold level.

If the power level of the received signal is higher than the threshold level, the WUR module (eg, 512 of FIG. 5) may determine the received signal as a 1-bit ON signal (ie, '1'). If the power level of the received signal is lower than the threshold level, the WUR module (eg, 512 of FIG. 5) may determine the received signal as a 1-bit OFF signal (ie, '0').

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

Generalizing the contents of FIG. 9, each signal having a length of K (eg, K is a natural number) in the 20 MHz band may be transmitted based on consecutive K subcarriers of 64 subcarriers for the 20 MHz band. For example, K may correspond to the number of subcarriers used to transmit the signal. K may also correspond to the bandwidth of a pulse according to the OOK technique.

All of the coefficients of the remaining subcarriers except K subcarriers among the 64 subcarriers may be set to '0'.

Specifically, for the 1-bit off signal corresponding to '0' (hereinafter, information 0) and the 1-bit on signal corresponding to '1' (hereinafter, information 1), the same K subcarriers may be used. have. For example, the index for the K subcarriers used may be expressed 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 view illustrating an EDCA-based channel access method in a WLAN system. An STA (or AP) performing enhanced distributed channel access (EDCA) in a WLAN system may perform channel access according to a plurality of user priorities defined for traffic data.

Specifically, to transmit quality of service (QoS) data frames based on a plurality of user priorities, four access categories (AC) (AC_BK (background), AC_BE (best effort), AC_VI (video), AC_VO (voice) may be defined.

The STA may receive traffic data (eg, MAC service data unit (MSDU)) with differential user priority from a logical link control (LLC) layer. User priority of traffic data arriving from the LLC layer to the medium access control (MAC) layer may be mapped as shown in Table 1 below.

In the present specification, the user priority may be understood as a traffic identifier (TID) indicating a characteristic of traffic data.

Referring to Table 1, traffic data having a user priority of '1' or '2' may be buffered into the transmission queue 1250 of the AC_BK type. Traffic data having a user priority of '0' or '3' may be buffered into the transmission queue 1240 of the AC_BE type. Traffic data having a user priority of '4' or '5' may be buffered into a transmission queue 1230 of type AC_VI. Traffic data having a user priority of '6' or '7' may be buffered into the transmission queue 1220 of the AC_VO type.

Instead of DIFS (DCFS interframe space), CWmin, CWmax, which is a parameter for the backoff procedure based on the existing distributed coordination function (DCF), AIFS (arbitration interframe), which is an EDCA parameter set, for the backoff procedure of an STA that performs EDCA space) [AC], CWmin [AC], CWmax [AC] and TXOP limit [AC] can be used.

Differences in transmission priority between ACs may be implemented based on the differential EDCA parameter set. The default value of the parameter EDCA parameter set (ie AIFS [AC], CWmin [AC], CWmax [AC], TXOP limit [AC]) corresponding to each AC is exemplarily shown in Table 2 below.

The EDCA parameter set for each AC may be set to a default value or carried in a beacon frame from the AP to each STA. The smaller the value of AIFS [AC] and CWmin [AC], the higher the priority. Therefore, the shorter the channel access delay, the more bandwidth can be used in a given traffic environment.

The EDCA parameter set may include information about channel access parameters (eg, AIFS [AC], CWmin [AC], CWmax [AC]) for each AC.

The backoff procedure for EDCA may be performed based on an EDCA parameter set individually set to four ACs included in each STA. Appropriate setting of EDCA parameter values, which define different channel access parameters for each AC, can optimize network performance and increase the transmission effect due to traffic priority.

Therefore, the AP of the WLAN system must perform overall management and coordination functions for the EDCA parameters to ensure fair access to all STAs participating in the network.

Each of the plurality of wireless terminals referred to herein may include a component (for example, 1010, 1020, 1030, 1040, 1050, 1060) as the example illustrated in FIG. 10.

Referring to FIG. 10, one STA (or AP) 1000 may include a virtual mapper 1010, a plurality of transmission queues 1020 to 1050, and a virtual collision handler 1060. The virtual mapper 1010 of FIG. 10 may serve to map an MSDU received from a logical link control (LLC) layer to a transmission queue corresponding to each AC according to Table 1 above.

The plurality of transmission queues 1020-1050 of FIG. 10 may serve as individual EDCA competition entities for channel access to the wireless medium within one STA (or AP).

For example, the transmission queue 1020 of the AC VO type of FIG. 10 may include one frame 1021 for a second STA (not shown). The transmission queue 1030 of the AC VI type may include three frames 1031 to 1033 for the first STA (not shown) and one frame 1034 for the third STA according to the order to be transmitted to the physical layer. Can be.

The transmission queue 1040 of the AC BE type of FIG. 10 has one frame 1041 for the second STA (not shown) and one frame for the third STA (not shown) according to the order to be transmitted to the physical layer. 1042 and one frame 1043 for a second STA (not shown). In exemplary embodiments, the transmission queue 1050 of the AC BE type of FIG. 10 may not include a frame to be transmitted to the physical layer.

For example, internal backoff values for transmission queue 1020 of type AC VO, transmission queue 1030 of type AC VI, transmission queue 1040 of type AC BE, and transmission queue 1050 of type AC BK. Can be calculated separately for each AC type based on Equation 1 below and a set of channel access parameters for each AC (ie, AIFS [AC], CWmin [AC], CWmax [AC] in Table 2).

The STA 1000 may perform an internal backoff procedure based on internal backoff values for each transmission queue 1020, 1030, 1040, and 1050. In this case, the transmission queue that first completes the internal backoff procedure may be understood as the transmission queue corresponding to the primary AC.

That is, the primary AC may mean an AC type corresponding to a transmission queue that first completes an internal backoff operation by the wireless terminal among four transmission queues mapped one-to-one to four AC types for the wireless terminal. . The secondary AC may refer to an AC type other than the primary AC.

Frames buffered in the transmission queue corresponding to the primary AC may be transmitted to another entity (eg, another STA or AP) during a transmission opportunity (TXOP). If there is more than one AC that has been backed off at the same time, collisions between ACs may be adjusted according to the functions included in the virtual collision handler 1060 (EDCA function, EDCAF).

In other words, if a collision occurs between ACs, a frame buffered in an AC having a higher priority may be transmitted first. Other ACs may also increase the contention window value and update the value set in the backoff count.

When a frame buffered in the transmission queue of the primary AC is transmitted, the STA may transmit the next frame in the same AC for the remaining TXOP time and determine whether it can receive an ACK. In this case, the STA attempts to transmit the next frame after the SIFS time interval.

The TXOP limit value may be set as a default value for the AP and the STA, or a frame associated with the TXOP limit value may be transferred from the AP to the STA. If the size of the data frame to be transmitted exceeds the TXOP limit, the AP may fragment the frame into several smaller frames. Subsequently, the divided frames may be transmitted in a range not exceeding the TXOP limit.

11 is a conceptual diagram illustrating a backoff procedure according to EDCA.

Each STA may share a wireless medium based on a contention coordination function, a distributed coordination function (hereinafter, referred to as 'DCF'). DCF is an access protocol for coordinating collisions between STAs, and may use carrier sense multiple access / collision avoidance (CSMA / CA).

If the DCF determines that the wireless medium is not used during the DCF inter frame space (DIFS) (that is, the wireless medium is in the idle state), the STA may acquire a transmission right for transmitting an internally determined MPDU through the wireless medium. . For example, the internally determined MPDU may be understood as a frame included in the transmission queue of the primary AC mentioned through FIG. 10.

If the DCF determines that the wireless medium is used by another STA in the DIFS (ie, the wireless medium is busy), the STA is idle for the wireless medium to obtain a transmission right to transmit an internally determined MPDU over the wireless medium. I can wait until it is in the idle state.

Subsequently, the STA may defer channel access by DIFS based on the time when the wireless medium is switched to the idle state. Subsequently, the STA may wait as much as a contention window (hereinafter referred to as "CW") set in the backoff counter.

In order to perform the backoff procedure according to the EDCA, each STA may set a randomly selected backoff value in the contention window (CW) to the backoff counter.

For example, the backoff value set in the backoff counter of each STA may be associated with an internal backoff value used in an internal backoff procedure for determining the primary AC of each STA.

As another example, the backoff value calculated based on Equation 1 below and a set of channel access parameters for primary STA of each STA (ie, AIFS [AC], CWmin [AC], CWmax [AC] in Table 2) It may be set in the backoff counter for each STA.

In this specification, a time indicating a backoff value selected by each STA in slot time units may be understood as the backoff window of FIG. 11.

Each STA may perform a countdown operation of decreasing the backoff window set in the backoff counter in slot time units. An STA having a relatively shortest backoff window among a plurality of STAs may acquire a transmission opportunity (TXOP), which is a right to occupy a wireless medium.

During the time period corresponding to the transmission opportunity (TXOP), the remaining STA may stop the countdown operation. The remaining STA may wait until the time period corresponding to the transmission opportunity (TXOP) ends. After the time interval corresponding to the transmission opportunity (TXOP) ends, the remaining STA may resume the suspended countdown operation to occupy the wireless medium.

According to the DCF-based transmission method, a collision phenomenon that may occur when a plurality of STAs simultaneously transmit a frame may be prevented. However, the channel access scheme using DCF has no concept of transmission priority (ie, user priority). That is, when DCF is used, the quality of service (QoS) of traffic to be transmitted by the STA cannot be guaranteed.

In order to solve this problem, a new coordination function (hybrid coordination function, hereinafter 'HCF') has been defined in 802.11e. The newly defined HCF has improved performance over the channel access performance of the existing DCF. HCF can use two channel access techniques, HCCA controlled channel access (HCCA) and polling-based enhanced distributed channel access (EDCA), for improving QoS.

Referring to FIG. 11, it may be assumed that the STA attempts to transmit the buffered traffic data to the STA. The user priority set for each traffic data may be differentiated as shown in Table 1 below. The STA may include four types of output queues mapped to the user priorities of Table 1 (AC_BK, AC_BE, AC_VI, and AC_VO).

The STA may transmit traffic data based on the Arbitration Interframe Space (AIFS) in place of the previously used DCF Interframe Space (DIFS).

Hereinafter, in an embodiment of the present invention, a wireless terminal (ie, STA) may be a device capable of supporting both a WLAN system and a cellular system. That is, the wireless terminal may be interpreted as a UE supporting the cellular system or an STA supporting the WLAN system.

Inter-frame spacing referred to in 802.11 is described for the sake of clarity herein. For example, the Interframe Interval (IFS) can be reduced interframe space (RIFS), short interframe space (SIFS), PCF interframe space (PIFS), DCF frame interval (DIFS). It may be a DCF interframe space, an arbitration interframe space (AIFS), or an extended interframe space (EIFS).

The interframe interval (IFS) may be determined according to an attribute specified by the physical layer of the STA regardless of the bit rate of the STA. The rest of the interframe intervals (IFS) except for AIFS may be understood as fixed values for each physical layer.

AIFS can be set to a value corresponding to four types of transmission queues mapped to user priorities as shown in Table 2 above.

SIFS has the shortest time gap among the above mentioned IFS. Accordingly, the STA occupying the wireless medium may be used when it is necessary to maintain the occupancy of the medium without interference by other STAs in the section in which the frame exchange sequence is performed.

That is, by using the smallest gap between transmissions in the frame exchange sequence, priority may be given to the completion of the ongoing frame exchange sequence. In addition, an STA accessing a wireless medium using SIFS may start transmission directly at the SIFS boundary without determining whether the medium is busy.

The duration of SIFS for a specific physical (PHY) layer may be defined by the aSIFSTime parameter. For example, in the physical layer (PHY) of the IEEE 802.11a, IEEE 802.11g, IEEE 802.11n and IEEE 802.11ac standards, the SIFS value is 16 μs.

PIFS can be used to provide the STA with the next highest priority after SIFS. In other words, PIFS can be used to obtain priority for accessing a wireless medium.

DIFS may be used by an STA to transmit a data frame (MPDU) and a management frame (Mac Protocol Data Unit (MPDU)) based on the DCF. If the medium is determined to be idle through a carrier sense (CS) mechanism after the received frame and the backoff time expire, the STA may transmit the frame.

12 is a view for explaining a frame transmission procedure in a WLAN system.

10 to 12, each of the STAs 1210, 1220, 1230, 1240, and 1250 of the WLAN system receives a backoff value for performing a backoff procedure according to the EDCA. 1240 and 1250 can be individually set to the backoff counter.

Each STA 1210, 1220, 1230, 1240, and 1250 may attempt transmission after waiting for the selected backoff value by a time indicated by a slot time (that is, the backoff window of FIG. 12).

In addition, each STA 1210, 1220, 1230, 1240, and 1250 may reduce the backoff window in slot time units through a countdown operation. The countdown operation for channel access to the wireless medium may be performed separately by each STA.

Each STA may individually set a backoff time Tb [i] corresponding to the backoff window to the backoff counter of each STA. Specifically, the backoff time Tb [i] is a pseudo-random integer value and may be calculated based on Equation 1 below.

Random (i) of Equation 1 is a function that uses a uniform distribution and generates a random integer between 0 and CW [i]. CW [i] may be understood as the contention window selected between the minimum contention window CWmin [i] and the maximum contention window CWmax [i].

For example, the minimum contention window CWmin [i] and the maximum contention window CWmax [i] may correspond to the default values CWmin [AC] and CWmax [AC] of Table 2, respectively.

For initial channel access, the STA may set CW [i] to CWmin [i] and use Random (i) to select a random integer between 0 and CWmin [i]. In this case, any integer selected can be referred to as a backoff value.

It can be understood that i in Equation 1 corresponds to the user priority in Table 1. That is, the traffic buffered in the STA may be understood to correspond to any one of AC_VO, AC_VI, AC_BE, or AC_BK of Table 1 based on the value set in i of Equation 1.

SlotTime of Equation 1 may be used to provide sufficient time for the preamble of the transmitting STA to be detected by the neighbor STA. Slot Time of Equation 1 may be used to define the aforementioned PIFS and DIFS. As an example. Slot time may be 9 μs.

For example, if the user priority i is '7', the initial backoff time Tb [7] for the transmission queue of type AC_VO slots the backoff value selected between 0 and CWmin [AC_VO]. It may be a time expressed in units of slot time.

When collision between STAs occurs according to the backoff procedure (or when ACK frame for the transmitted frame is not received), the STA increases the backoff time Tb [i] 'based on Equation 2 below. Can be newly calculated.

Referring to Equation 2, the new contention window CW _new [i] may be calculated based on the previous window CW _old [i]. The PF value of Equation 2 may be calculated according to the procedure defined in the IEEE 802.11e standard. For example, the PF value of Equation 2 may be set to '2'.

In this embodiment, the increased backoff time Tb [i] 'is equal to the slot time of any integer selected between 0 and the new contention window CW _new [i]. It can be understood as time expressed in units.

CWmin [i], CWmax [i], AIFS [i], and PF values mentioned in FIG. 12 may be signaled from the AP through a QoS parameter set element, which is a management frame. The CWmin [i], CWmax [i], AIFS [i] and PF values may be preset values by the AP and the STA.

Referring to FIG. 12, the horizontal axes t1 to t5 for the first to fifth STAs 1210 to 1250 may represent a time axis. In addition, the vertical axis for the first to fifth STAs 1210 to 1250 may indicate a backoff time transmitted.

10 to 12, when a specific medium is changed from occupy or busy to idle, a plurality of STAs may attempt data (or frame) transmission.

At this time, in order to minimize the collision between STAs, each STA selects the backoff time (Tb [i]) of Equation 1 and waits for the corresponding slot time (slot time) before transmitting. You can try

When the backoff procedure is initiated, each STA may count down the individually selected backoff counter time in slot time units. Each STA may continue to monitor the medium while counting down.

If the wireless medium is monitored as occupied, the STA may stop counting down and wait. If the wireless medium is monitored in an idle state, the STA can resume counting down.

Referring to FIG. 12, when the frame for the third STA 1230 reaches the MAC layer of the third STA 1230, the third STA 1230 may check whether the medium is idle during DIFS. Subsequently, when the medium is determined to be idle during DIFS, the third STA 1230 may transmit a frame to an AP (not shown). However, although the inter frame space (IFS) of FIG. 12 is illustrated as DIFS, it will be understood that the present specification is not limited thereto.

While the frame is transmitted from the third STA 1230, the remaining STA may check the occupation state of the medium and wait for the transmission interval of the frame. A frame may reach the MAC layer of each of the first STA 1210, the second STA 1220, and the fifth STA 1250. If the medium is identified as idle, each STA may wait for DIFS and then count down the individual backoff time selected by each STA.

Referring to FIG. 12, the second STA 1220 selects the smallest backoff time and the first STA 1210 selects the largest backoff time. The remaining backoff time of the fifth STA 1250 is the remaining backoff of the first STA 1210 at the time T1 after completing the backoff procedure for the backoff time selected by the second STA 1220 and starting frame transmission. A case shorter than the off time is shown.

When the medium is occupied by the second STA 1220, the first STA 1210 and the fifth STA 1250 may suspend and wait for the backoff procedure. Subsequently, when the media occupation of the second STA 1220 ends (that is, the medium is idle again), the first STA 1210 and the fifth STA 1250 may wait as long as DIFS.

Subsequently, the first STA 1210 and the fifth STA 1250 may resume the backoff procedure based on the stopped remaining backoff time. In this case, since the remaining backoff time of the fifth STA 1250 is shorter than the remaining backoff time of the first STA 1210, the fifth STA 1250 may complete the backoff procedure before the first STA 1210. Can be.

Meanwhile, referring to FIG. 12, when a medium is occupied by the second STA 1220, a frame for the fourth STA 1240 may reach the MAC layer of the fourth STA 1240. When the medium is in the idle state, the fourth STA 1240 may wait as long as DIFS. Subsequently, the fourth STA 1240 may count down the backoff time selected by the fourth STA 1240.

Referring to FIG. 12, the remaining backoff time of the fifth STA 1250 may coincide with the backoff time of the fourth STA 1240. In this case, a collision may occur between the fourth STA 1240 and the fifth STA 1250. If a collision occurs between STAs, neither the fourth STA 1240 nor the fifth STA 1250 may receive an ACK, and may fail to transmit data.

Accordingly, the fourth STA 1240 and the fifth STA 1250 may separately calculate a new contention window CW _new [i] according to Equation 2 above. Subsequently, the fourth STA 1240 and the fifth STA 1250 may separately perform countdowns for the newly calculated backoff time according to Equation 2 above.

Meanwhile, when the medium is occupied due to transmission of the fourth STA 1240 and the fifth STA 1250, the first STA 1210 may wait. Subsequently, when the medium is in an idle state, the first STA 1210 may resume backoff counting after waiting for DIFS. When the remaining backoff time of the first STA 1210 elapses, the first STA 1210 may transmit a frame.

The CSMA / CA mechanism may include virtual carrier sensing in addition to physical carrier sensing in which the AP and / or STA directly sense the medium.

Virtual carrier sensing is intended to compensate for problems that may occur in media access, such as a hidden node problem. For virtual carrier sensing, the MAC of the WLAN system uses a Network Allocation Vector (NAV). The NAV is a value that indicates to the other AP and / or STA how long the AP and / or STA currently using or authorized to use the medium remain until the medium becomes available.

Therefore, the value set to NAV corresponds to a period in which the medium is scheduled to be used by the AP and / or STA transmitting the frame, and the STA receiving the NAV value is prohibited from accessing the medium during the period. For example, the NAV may be set according to a value of a duration field of the MAC header of the frame.

13 shows a block diagram of a wireless terminal for a procedure of transmitting a wake-up packet in a WLAN system.

Referring to FIG. 13, the WLAN system 1300 according to the present embodiment may include a first wireless terminal 1310 and a second wireless terminal 1320.

The first wireless terminal 1310 includes a main radio module 1311 and a low-power wake-up receiver (LP WUR) associated with the main radio (ie, 802.11) (hereinafter, WUR). Module 1312. The main radio module 1311 may transmit user data or receive user data in an activated state (ie, an ON state).

If there is no data (or data packet) to be transmitted by the main radio module 1311, the first wireless terminal 1310 may instruct the main radio module 1311 to enter an inactive state (ie, an OFF state). .

For example, the main radio module 1311 may include a plurality of circuits supporting Wi-Fi, a Bluetooth® radio (hereinafter referred to as BT radio) and a Bluetooth® Low Energy radio (hereinafter referred to as BLE radio).

Modules (eg, 1311 and 1312) of a wireless terminal in an inactive state (OFF state) according to the present embodiment 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 1311 in an inactive state (ie, in an OFF state) according to the present embodiment may not receive a beacon frame periodically transmitted by the AP until it is woken by the WUR module 1312.

In addition, the wireless terminal according to the present embodiment may receive a frame (or packet) from another wireless terminal based on the main radio module 1311 or the WUR module 1312 in an activated state.

That is, the WUR module 1312 may be understood as a configuration for waking up the main radio module 1311. That is, the WUR module 1312 may not include a transmitter.

The first wireless terminal 1310 can instruct the WUR module 1312 to maintain the activated state for a duration in which the main radio module 1311 is in an inactive state. Accordingly, a wake-up packet for the main radio module 1311 may be received based on the WUR module 1312 in an activated state.

The low power wake-up receiver (LP WUR) included in the WUR module 1312 targets a target power consumption of less than 1 mW in an 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 1320 according to the present embodiment may transmit a packet for the first wireless terminal 1310 based on a main radio (that is, 802.11). The second wireless terminal 1320 can transmit a wakeup packet (WUP) 1321 to the WUR module 1312 of the first wireless terminal 1310.

In this case, the main radio module 1311 included in the first wireless terminal 1310 may be in an inactive state (ie, an OFF state). WUR module 412 may be in an active state (ie, in an ON state).

Referring to FIG. 13, the wakeup packet 1321 may be received based on the WUR module 1312 in an activated state. In this case, in order to correctly receive the data packet 1322 to be received after the wakeup packet 1321, the first wireless terminal 1310 instructs the main radio module 1311 to enter an activated state. ) Can be delivered.

For example, the wakeup signal 1323 may be implemented based on primitive information inside the receiving terminal 1310.

For example, the first wireless terminal 1310 activates all of a plurality of circuits (not shown) supporting Wi-Fi, BT radio, and BLE radio included in the main radio module 1311 according to the wake-up signal 1323. Can be activated or only part of it.

As another example, actual data (ie, payload) included in the wakeup packet 1321 may be directly transmitted to a memory block (not shown) of the receiving terminal even if the main radio module 1311 is in an inactive state.

As another example, when the wake-up packet 1321 includes the IEEE 802.11 MAC frame, the receiving terminal may activate only the MAC processor of the main radio module 1311. That is, the receiving terminal may maintain the PHY module of the main radio module 1311 in an inactive state.

14 is a diagram for describing a method for managing power of a wireless terminal in a wireless LAN system according to the present embodiment.

1 to 14, the AP 1410 of FIG. 14 corresponds to the second wireless terminal 1320 of FIG. 13, and the WUR STA 1420 corresponds to the first wireless terminal 1310 of FIG. 13. Can be.

For clear and concise description of FIG. 14, the AP 1410 buffers a data packet (not shown) for the WUR STA 1420, and the main radio module (eg, 1311 of FIG. 13) of the WUR STA 1420 Assume that it is in an inactive state.

In addition, the WUR module (eg, 1312 of FIG. 13) of the WUR STA 1420 may be configured as a main radio module (eg, FIG. 13) in an inactive state based on a received wake-up packet. 1311) may be configured to switch to an activated state. That is, the WUR module (eg, 1312 of FIG. 13) of the WUR STA 1420 may not include a transmitter.

The horizontal axis of the AP 1410 may represent the time t1 of the AP 1410. The vertical axis of the AP 1410 may be associated with the presence of a frame to be transmitted by the AP 1410. The horizontal axis of the WUR STA 1420 may represent the time t2 of the WUR STA 1420. The vertical axis of the WUR STA 1420 may be associated with the presence of a frame to be transmitted by the WUR STA 1420.

At the first time point T1 of FIG. 14, as an example, the AP 1410 first completes the backoff procedure in the relationship with the WUR STA 1420 as well as other wireless terminals (not shown) (ie, first). The terminal has completed the countdown operation).

In addition, at the first time point T1, the AP 1410 may be a terminal that has won a channel competition with another wireless terminal (not shown) including the WUR STA 1420. That is, the AP 1410 may be understood as a wireless terminal that has obtained channel access to a wireless medium. The wireless terminal acquiring the channel access may transmit a buffered packet (or frame) during the transmission opportunity (TXOP).

Referring to FIG. 14, the backoff counter of the AP 1410 whose value other than '0' is preset arrives at '0' before the WUR STA 1420 as well as other wireless terminals (not shown) through a countdown operation. can do.

In the first period T1 to T2, the AP 1410 may transmit a wakeup packet (WUP) instructing the main radio module of the WUR STA 1420 to enter an activation state. For example, a wakeup packet (WUP) may be understood as a frame transmitted through a contention-based channel access procedure such as EDCA.

According to the present embodiment, the manner in which the wake-up packet WUP is transmitted may be as follows.

In a first manner, the wakeup packet WUP may be transmitted based on the same EDCA parameter set as the data packet (not shown) to be transmitted to the AP 1410 subsequent to the wakeup packet WUP.

For example, the data packet (not shown) may be internally determined among the first to fourth access categories (ie, AC VO, AC VI, AC BE, AC BK) for the Quality of Service (QoS) of the AP 1410. It may be buffered in a transmission queue corresponding to primary AC.

For example, the same EDCA parameter set as the data packet (not shown) is the AIFS [AC] of Table 2 and the TXOP of AP 1410, which is a preset time for the transmission queue corresponding to the primary AC of AP 1410. It may include an associated TXOP limit value (eg, TXOP limit [AC] in Table 2).

In addition, the same EDCA parameter set as the data packet (not shown) is used for retransmission of the AP 1410 and the minimum contention window value (eg CWmin [AC] in Table 2) for the initial backoff value set in the AP 1410. And a maximum contention window value for the contention window to be increased accordingly (eg, CWmax [AC] in Table 2).

In a second manner, the wake-up packet WUP may be configured to include first to fourth transmission queues (eg, AC VO, AC VI, AC BE, and AC BK) of the AP 1410. 1010, 1030, 1040, and 1050 of FIG. 10 may be transmitted based on an EDCA parameter set for a transmission queue.

In a third manner, a new EDCA parameter set (hereinafter, 'WUR EDCA parameter set') for transmitting a wakeup packet (WUP) may be defined.

For example, the newly defined WUR EDCA parameter set may have the same form as the legacy EDCA parameter set of Table 2 above. For example, the WUR EDCA parameter set may include AIFS [AC], CWmin [AC], CWmax [AC], and TXOP limit [AC].

The WUR EDCA parameter set may be used for a wake up packet (WUP) that directs the main radio module to enter an activated state. The wireless terminal receiving the wakeup packet WUP may transmit an acknowledgment packet for the wakeup packet WUP based on the main radio module entering the activation state.

According to this embodiment, it may be desirable to be defined in a form that does not increase the congestion (congestion) of the legacy 802.11 network.

In addition, the wakeup packet (WUP) may be defined as a value different from the legacy EDCA parameter set previously defined because it has a different purpose from data transmission in an 802.11 network.

For example, the WUR EDCA parameter set for the wakeup packet (WUP) may be set to a larger value (ie, a longer value) than the legacy EDCA parameter set so as not to significantly affect the load of the legacy legacy network.

As an example, the WUR EDCA parameter set for the wakeup packet (WUP) may be set to a smaller value (i.e., shorter) than the legacy EDCA parameter set, taking into account that it is sent before a normal data packet to wake up the main radio module. Can be set.

When a wakeup packet (WUP) has a higher priority than an existing packet transmitted based on the legacy EDCA parameter set, a value smaller than the legacy EDCA parameter set (ie, a shorter value) for the WUR EDCA parameter set. Can be set.

In order to reduce unnecessary power consumption by the wireless terminal, when the WUP response packet is transmitted through EDCA channel access, the WUR EDCA parameter set may be set to have a higher priority than the existing one. Can be.

The second section T2 to T3 may be understood as a time section corresponding to a turn-on delay (hereinafter, referred to as 'TOD').

The turn-on delay TOD is required for the main radio module (eg, 1311 of FIG. 13) to enter the activated state (ie, the ON state) from the inactive state (ie, the OFF state) according to the wake-up packet WUP. It can be time to be. For example, the wakeup signal may be implemented based on primitive information inside the WUR STA 1420.

The second periods T2 to T3 corresponding to the turn-on delay TOD may be a time period longer than the SIFS.

In the third period T3 to T4, the WUR STA 1420 may transmit a WUP response packet to the AP 1410 in response to the wakeup packet (WUP).

For example, the WUR STA 1420 may use a QoS null frame that does not include a payload as a WUP response packet. As another example, the WUR STA 1420 may use a PS-poll frame, which is a response to the beacon frame, as a WUP response packet.

The turn-on delays TOD and T2 to T3 may be longer than SIFS. Accordingly, the WUP response packet according to the present embodiment may be transmitted on a contention basis in relation to not only the AP 1410 but also other wireless terminals (not shown). For example, the WUP response packet may be understood as a frame transmitted through a contention based channel access procedure such as EDCA.

In addition, the WUP response packet according to the present embodiment may be transmitted based on an EDCA parameter set having a priority level higher than that of a normal data packet.

In FIG. 14, the WUR STA 1420 may be understood as a wireless terminal combined with the AP 1410 according to an association procedure. Although only one wireless terminal 1420 is shown in FIG. 14 in conjunction with the AP 1410, it will be understood that the present disclosure is not limited thereto.

In addition, although the wakeup packet (WUP) is shown as being transmitted by the AP 1410 in FIG. 14, it is to be understood that the present disclosure is not limited thereto and may also be transmitted by the WUR STA 1420.

15 to 17 are diagrams illustrating a method for managing power of a wireless terminal by reflecting a turn-on delay in a wireless LAN system according to the present embodiment.

15 to 17 are described on the premise that a transmission operation by the WUR modules 1512, 1612, and 1712 is not supported (that is, only a reception operation is supported).

Referring to FIG. 15, the first wireless terminal 1510 of FIG. 15 may correspond to the first wireless terminal 1310 of FIG. 13. The main radio module 1511 of FIG. 15 may correspond to the main radio module 1311 of FIG. 13. The WUR module 1512 of FIG. 15 may correspond to the WUR module 1312 of FIG. 13.

The vertical axis of the main radio module 1511 of FIG. 15 may represent the time t1 of the main radio module 1511. The vertical axis of the WUR module 1512 may represent the time t2 of the WUR module 1512.

The second wireless terminal 1520 of FIG. 15 may correspond to the second wireless terminal 1320 of FIG. 13. The vertical axis of the second wireless terminal 1520 of FIG. 15 may represent time t3 of the second wireless terminal 1520.

In the first period T1 to T2, it is assumed that the main radio module 1511 of the first wireless terminal 1510 is in an inactive state and the WUR module 1512 is in an active state.

According to the above assumption, since the main radio module 1511 is in an inactive state, the first wireless terminal 1510 may not receive a beacon frame periodically received from the second wireless terminal 1520.

Unlike the above assumption, if the main radio module 1511 is in an active state, the first radio terminal 1510 may transmit a packet for the second radio terminal 1520 based on the main radio module 1511.

Unlike the above assumption, if the main radio module 1511 is in an active state, the first radio terminal 1510 may receive a packet including a beacon frame from the second radio terminal 1520 based on the main radio module 1511. have.

In the first period T1 to T2, the second wireless terminal 1520 may perform contention-based channel access with another wireless terminal (not shown).

For example, each of the first wireless terminal 1510 and the second wireless terminal 1520 sharing the wireless medium may individually perform a countdown operation according to the backoff value set in the backoff counter of each wireless terminal. .

For clarity and concise description of FIG. 15, it is assumed that at the second time point T2, the second wireless terminal 1520 first completes the countdown operation. That is, the second wireless terminal 1520 of FIG. 15 may be understood as a wireless terminal obtained a transmission opportunity (TXOP) for the wireless medium.

For operation S1510, the second wireless terminal 1520 may transmit a wakeup packet (WUP) to the first wireless terminal 1510 instructing the main radio module 1511 to enter the activated state.

For example, a wakeup packet (WUP) may be received by the WUR module 1512 in an activated state.

The wakeup packet (WUP) is a reception address (RA) information for indicating the receiving terminal of the wakeup packet (WUP) and the transmission opportunity (TXOP) obtained by the second wireless terminal 1520. Duration information (for example, T1 to T6 of FIG. 15) may be included.

The first wireless terminal 1510 may be indicated by the reception address RA information of the wakeup packet WUP. In this case, the first wireless terminal 1510 may demodulate all the wakeup packets WUP.

In addition, the first wireless terminal 1510 may acquire duration information (eg, T1 to T6 of FIG. 15) for the transmission opportunity TXOP included in the wakeup packet WUP.

However, the duration information for the transmission opportunity (TXOP) of FIG. 15 is just an example, and it will be understood that the present embodiment is not limited thereto. In other words, the duration information for the transmission opportunity TXOP indicates a time interval (for example, T2 to T6) in which the time T1 to T2 required for the backoff procedure by the second wireless terminal 1520 is excluded. It can be set to.

The other wireless terminal (not shown) that receives the wakeup packet WUP from the first wireless terminal 1510 is duration information for the transmission opportunity TXOP regardless of the reception address RA information of the wakeup packet WUP. (For example, T1 to T6 in FIG. 15) can be obtained.

In addition, another wireless terminal (not shown) not indicated by the reception address RA information of the wake-up packet WUP is NAV according to the duration information (for example, T1 to T6 in FIG. 15) for the transmission opportunity TXOP. Can be set.

As described above with reference to FIG. 14, a scheme of transmitting the wakeup packet (WUP) of FIG. 15 may vary. For example, the wakeup packet WUP may be transmitted based on the same EDCA parameter set as the data packet.

For operation S1520, the first wireless terminal 1510 receives a wakeup signal instructing the main radio module 1511 to enter an activated state according to a wakeup packet WUP received through the WUR module 1512. Transfer to module 1511.

For example, after a time point T2 ′ where reception of the wakeup packet WUP is completed, the wakeup signal may be transmitted to the main radio module 1511.

In this specification, the time taken for the main radio module 1511 in the deactivated state to enter the activated state according to the wake-up signal may be referred to as a turn-on delay (TOD). The turn-on delay TOD according to the present embodiment may be longer than SIFS.

In operation S1530, the main radio module 1511 may enter an active state capable of receiving a packet for the first wireless terminal 1510 from the second wireless terminal 1520.

For step S1540, the first wireless terminal 1510 at a third time point T3 after a predetermined time (eg, SIFS) has elapsed from the time point T2 ″ where the main radio module 1511 enters the activated state. May transmit the first response packet to the second wireless terminal 1520 without contention with another wireless terminal (eg, 1520) using the main radio module 1511.

The first acknowledgment packet may be understood as a packet for informing the second wireless terminal 1520 of the successful reception of the wakeup packet (WUP). The first reply packet may be transmitted during the third period T3 ˜ T3 ′ of FIG. 15.

Alternatively, the first acknowledgment packet may be transmitted with another wireless terminal (eg, 1520) through a contention-based channel access procedure such as EDCA.

The second section T2 to T3 of FIG. 15 may be understood as a time corresponding to the turn-on delay TOD and the SIFS.

For step S1550, at a fourth time point T4 after a predetermined time (eg, SIFS) has elapsed from the transmission completion time point T3 ′ of the first response packet, the second wireless terminal 1520 is the first wireless terminal. A data packet for 1510 may be transmitted without contention with another wireless terminal (eg, 1510).

The data packet may be transmitted to the first wireless terminal 1510 during the fourth period T4 to T4 ′ of FIG. 15. In detail, a data packet for the first wireless terminal 1510 may be received through the main radio module 1511 of the first wireless terminal 1511.

For step S1560, at a fifth time point T5 after a predetermined time (eg, SIFS) has elapsed from the completion time point T4 'of the data packet transmission, the first wireless terminal 1510 receives successful reception of the data packet. A second acknowledgment packet to inform may be transmitted without contention with another wireless terminal (eg, 1520).

The second acknowledgment packet may be understood as a packet for informing the second wireless terminal 1520 of the successful receipt of the data packet. The second reply packet may be transmitted to the second wireless terminal 1520 through the main radio module 1511 of the first wireless terminal 1511 during the fifth section T5 ˜ T5 ′ of FIG. 15.

Alternatively, the second acknowledgment packet may be transmitted with another wireless terminal (eg, 1520) via a contention-based channel access procedure such as EDCA.

Although not shown in FIG. 15, the second wireless terminal 1520 receiving the second response packet may truncate the remaining TXOP periods T5 'to T6.

Referring to FIG. 16, the first wireless terminal 1610 of FIG. 16 may correspond to the first wireless terminal 1510 of FIG. 15. In addition, the main radio module 1611 of FIG. 16 may correspond to the main radio module 1511 of FIG. 15. The WUR module 1612 of FIG. 16 may correspond to the WUR module 1512 of FIG. 15.

It will be appreciated that the description of the first sections T1 to T2 of FIG. 16 may be replaced with the description of the first sections T1 to T2 of FIG. 15.

For operation S1610, at the second time point T2, the second wireless terminal 1620 may transmit a wakeup packet WUP to the first wireless terminal 1610.

Unlike in FIG. 15, the second wireless terminal 1620 of FIG. 16 wakes up the duration information for the transmission opportunity (TXOP) obtained by the second wireless terminal 1520 in consideration of a turn-on delay (TOD). It may not be included in the (WUP).

For example, the first wireless terminal 1610 of FIG. 16 may be indicated by the reception address RA information of the wakeup packet WUP. The first wireless terminal 1610 can demodulate all of the wake-up packets (WUP).

For operation S1620, the first wireless terminal 1610 may transmit a wake-up signal for instructing the main radio module 1611 to enter the activated state to the main radio module 1611.

For example, after a time point T2 ′ where reception of the wakeup packet WUP is completed, the wakeup signal may be transmitted to the main radio module 1611. The turn-on delay (TOD) for the main radio module 1611 to enter the activated state may be longer than SIFS.

In operation S1630, the main radio module 1611 may enter an active state capable of receiving a packet for the first wireless terminal 1610 from the second wireless terminal 1620.

Subsequently, after the main radio module 1611 enters the activated state, the first wireless terminal 1610 may perform contention-based channel access such as EDCA with the second wireless terminal 1620.

For clarity and concise description of FIG. 16, it is assumed that at the third time point T3, the first wireless terminal 1610 completes the countdown operation first. That is, at the third time point T3, the first wireless terminal 1610 of FIG. 16 may be understood as a wireless terminal that acquires a transmission opportunity (TXOP) for a wireless medium.

For operation S1640, the first wireless terminal 1610 may transmit a first response packet to the second wireless terminal 1620. The first reply packet may be transmitted based on the main radio module 1611 in an activated state.

For example, at the third time point T3, the first wireless terminal 1610 receives duration information (for example, T3 to T6) for the transmission opportunity TXOP obtained by the first wireless terminal 1610. It can be included in the first reply packet.

Accordingly, the second wireless terminal 1620 may acquire duration information (for example, T3 to T6 of FIG. 16) for the transmission opportunity (TXOP) included in the first response packet.

Also, another wireless terminal (not shown) not indicated by the reception address RA information of the first acknowledgment packet may set the NAV according to the duration information (for example, T3 to T6 in FIG. 16) for the transmission opportunity TXOP. Can be.

The duration information for the transmission opportunity (TXOP) shown in FIG. 16 is merely an example, and it will be understood that the present embodiment is not limited thereto. As another example, the duration information for the transmission opportunity (TXOP) indicates a time interval (eg, T2 ″ ˜ T6) including a time T2 ″ ˜ T3 spent in the backoff procedure by the first wireless terminal 1610. It can be set to.

For step S1650, at a fourth time point T4 after a predetermined time (eg, SIFS) has elapsed from the transmission completion time point T3 ′ of the first response packet, the second wireless terminal 1620 is the first wireless terminal. The data packet buffered for 1610 may be transmitted without contention with another wireless terminal (eg, 1610).

The buffered data packet may be transmitted to the first wireless terminal 1610 during the fourth period T4 ˜ T4 ′ of FIG. 16. In detail, the data packet for the first wireless terminal 1610 may be received through the main radio module 1611 of the first wireless terminal 1611.

Or, the data packet may be transmitted through a contention-based channel access procedure such as EDCA with another wireless terminal (eg, 1610).

For step S1660, at a fifth time point T5 after a predetermined time (for example, SIFS) has elapsed from the completion time point T4 'of the data packet transmission, the first wireless terminal 1610 receives successful reception of the data packet. A second acknowledgment packet to inform may be transmitted without contention with another wireless terminal (eg, 1620).

The second acknowledgment packet may be understood as a packet for notifying the second wireless terminal 1620 of the successful reception of a data packet. The second reply packet may be transmitted to the second wireless terminal 1620 during the fifth period T5 ˜ T5 ′ of FIG. 16.

Alternatively, the second acknowledgment packet may be transmitted via a contention-based channel access procedure such as EDCA with another wireless terminal (eg, 1610).

Although not shown in FIG. 16, the second wireless terminal 1620 receiving the second response packet may truncate the remaining TXOP periods T5 ′ to T6.

Referring to FIG. 17, the first wireless terminal 1710 of FIG. 17 may correspond to the first wireless terminal 1510 of FIG. 15. In addition, the main radio module 1711 of FIG. 17 may correspond to the main radio module 1511 of FIG. 15. The WUR module 1712 of FIG. 17 may correspond to the WUR module 1512 of FIG. 15.

It will be appreciated that the description of the first sections T1 to T2 of FIG. 17 may be replaced with the description of the first sections T1 to T2 of FIG. 15.

For operation S1710, the second wireless terminal 1720 may transmit a wakeup packet WUP to the first wireless terminal 1710 at a second time point T2. The wakeup packet WUP according to the present embodiment may include a payload modulated according to the on-off keying (OOK) technique as described with reference to FIG. 9.

The payload of the wakeup packet WUP is determined to be an ON signal determined by the WUR module 1712 as a 1 bit ON signal and a 1 bit OFF signal by the WUR module 1712. The OFF signal may be implemented based on the OFF signal.

As shown in FIG. 9, the on signal is N2 (eg, consecutive 13) of N1 (eg, 64) subcarriers corresponding to the first channel band (eg, 20 MHz band) of the wake-up packet WUP. It can be obtained by performing an Inverse Fast Fourier Transform (IFFT) on each subcarrier.

For example, the IFFT may be a 64-point IFFT. In addition, the subcarrier spacing applied to the wake-up packet (WUP) may be 312.5 kHz.

For example, a first preset sequence may be applied to the N2 subcarriers. The preset first sequence may be a 13-bit sequence. The coefficient corresponding to the DC subcarrier in the 13-bit sequence is '0', and the remaining coefficients may be set to '1' or '-1'.

In detail, a coefficient of a DC subcarrier having a DC (Direct Current) frequency among subcarrier sets (eg, 921 of FIG. 9) may be set to '0'. In addition, the coefficients of the remaining subcarriers except the DC subcarrier in the subcarrier set (eg, 921 of FIG. 9) may be set to '1' or '-1'.

The off signal may not be transmitted at all. Or IFFT (N) (e.g., 13 consecutive) subcarriers of N1 (e.g., 64) subcarriers corresponding to the first channel band (e.g., 20 MHz band) of the wake-up packet (WUP). It can be obtained by performing an Inverse Fast Fourier Transform.

However, a second preset sequence may be applied to the N2 subcarriers. For example, the second preset sequence may be a 13-bit sequence. All coefficients of the 13-bit sequence may be set to '0'.

Unlike FIG. 15, the second wireless terminal 1720 of FIG. 17 wakes up the duration information for the transmission opportunity (TXOP) obtained by the second wireless terminal 1720 in consideration of a turn-on delay (TOD). It may not be included in the (WUP).

For example, the first wireless terminal 1710 of FIG. 17 may be indicated by reception address RA information of the wakeup packet WUP. The first wireless terminal 1710 can demodulate all of the wakeup packets (WUP).

For operation S1720, the first wireless terminal 1710 may transmit a wake-up signal for instructing the main radio module 1711 to enter the activated state to the main radio module 1711. Specifically, after the time point T2 ′ where reception of the wakeup packet WUP is completed, the wakeup signal may be transmitted to the main radio module 1711.

The turn-on delay (TOD) for the main radio module 1711 to enter the activated state may be longer than SIFS.

In operation S1730, the first wireless terminal 1710 may enter an activation state capable of receiving a packet for the first wireless terminal 1710 from the second wireless terminal 1720.

Subsequently, after the main radio module 1711 enters the activated state, the first wireless terminal 1710 may be based on a contention-based competition such as EDCA in relation to not only the second wireless terminal 1720 but also other wireless terminals (not shown). Channel access can be performed.

For clarity and concise description of FIG. 17, it is assumed that the first wireless terminal 1710 first completes the countdown operation at the third time point T3.

At a third time point T3, the first wireless terminal 1710 of FIG. 17 may acquire a transmission opportunity (TXOP) for the wireless medium. That is, at the third time point T3, the first wireless terminal 1710 of FIG. 17 uses a contention-based channel access procedure such as EDCA and another wireless terminal (not shown) including the second wireless terminal 1720. It can be understood as a terminal obtaining the access.

For operation S1740, at a third time point T3, the first wireless terminal 1710 may transmit a first response packet to the second wireless terminal 1720. The first reply packet may be transmitted via the main radio module 1711 in an activated state.

At a third time point T3, unlike FIG. 16, the first wireless terminal 1710 of FIG. 17 includes duration information for a transmission opportunity (TXOP) obtained by the first wireless terminal 1710 in the first response packet. You can't let that happen.

For clarity and concise description of FIG. 17, it is assumed that the second wireless terminal 1720 first completes the countdown operation at the fourth time point T4. At a fourth time point T4, the second wireless terminal 1720 of FIG. 17 may be understood as a wireless terminal that has acquired a transmission opportunity (TXOP) for the wireless medium.

In other words, at the fourth time point T4, the second wireless terminal 1710 of FIG. 17 may use a contention-based channel access procedure such as EDCA and another wireless terminal (not shown) including the first wireless terminal 1710. It can be understood as a terminal acquiring channel access.

For operation S1750, the second wireless terminal 1720 may transmit a data packet for the first wireless terminal 1710. In this case, the data packet for the first wireless terminal 1710 may be understood as a packet buffered by the second wireless terminal 1720.

The data packet for the first wireless terminal 1710 may be received via the main radio module 1711 of the first wireless terminal 1711.

For example, the data packet for the first wireless terminal 1710 may be configured to protect the left band of N3 (eg, 64) subcarriers corresponding to the second channel band (eg, 20 MHz band) of the data packet. N4 (e.g. 4) subcarriers, N5 (e.g. 3) subcarriers to protect the right band and N6 (e.g. 56) subs except DC subcarriers corresponding to the DC frequency It can be transmitted based on the carrier.

The first channel band of the wakeup packet and the second channel band of the data packet may be the same band. However, the present disclosure is not limited thereto, and the first channel band of the wakeup packet and the second channel band of the data packet may be different channel bands.

In addition, the data packet of FIG. 17 is a primary access category (ie, primary) determined internally by the second wireless terminal 1720 among the first to fourth access categories for the second wireless terminal 1720. It may be included in a transmission queue corresponding to AC). The procedure by which the primary AC is determined internally by the wireless terminal can be understood through the description associated with FIGS. 10 and 11 above.

The second wireless terminal 1720 may include duration information (eg, T4 to T6 of FIG. 17) for a transmission opportunity (TXOP) obtained by the second wireless terminal 1720 in the data packet.

The first wireless terminal 1710 may obtain duration information (eg, T4 to T6 of FIG. 17) for a transmission opportunity (TXOP) from the received data packet. In addition, another wireless terminal (not shown) not indicated by the reception address (RA) information of the data packet may set the NAV according to the duration information (for example, T4 to T6 in FIG. 17) for the transmission opportunity TXOP. .

The duration information for the transmission opportunity (TXOP) shown in FIG. 17 is only an example, and it will be understood that the present embodiment is not limited thereto. As another example, the duration information for the transmission opportunity (TXOP) indicates a time interval (for example, T3 'to T6) including a time (T3' to T4) required for the backoff procedure by the first wireless terminal 1710. It can be set to.

For step S1760, at a fifth time point T5 after a predetermined time (for example, SIFS) has elapsed from the completion time point T4 'of the data packet transmission, the first wireless terminal 1710 receives successful reception of the data packet. A second acknowledgment packet to inform may be transmitted without contention with another wireless terminal (eg, 1720).

The second acknowledgment packet may be understood as a packet for notifying the second wireless terminal 1720 of the successful reception of a data packet. The second reply packet may be transmitted to the second wireless terminal 1720 during the fifth section T5 ˜ T5 ′ of FIG. 17.

Alternatively, the second acknowledgment packet may be transmitted via a contention-based channel access procedure such as EDCA with another wireless terminal (eg, 1710). Although not shown in FIG. 17, the second wireless terminal 1720 receiving the second response packet may truncate the remaining TXOP periods T5 'to T6.

As mentioned with reference to FIGS. 15 through 17, the transmission operation by the WUR modules 1512, 1612, and 1712 may not be supported due to a problem of power consumption by the wireless terminal.

 In this case, the wireless terminal receiving the wakeup packet WUP may transmit a WUR reply packet for the wakeup packet WUP based on the main radio module in the activated state after the main radio module enters the activated state. Can be.

In this case, the WUR acknowledgment packet transmitted through the main radio module may use a PS-poll frame that is a response to the beacon frame or a QoS null frame that does not include a payload:

According to the present embodiment, since the transmission operation by the WUR modules 1512, 1612, and 1712 is not supported, a turn-on delay (TOD) that takes place for the main radio module to enter the activated state may occur. This means that the wireless terminal that receives the wakeup packet (WUP) cannot respond immediately after SIFS.

That is, this means that the wireless terminal receiving the wakeup packet (WUP) should transmit an acknowledgment (ACK) frame for the wakeup packet (WUP) through a channel contention such as EDCA with another wireless terminal.

In addition, an acknowledgment (ACK) frame for the wakeup packet (WUP) may be transmitted based on the legacy EDCA parameter set. The acknowledgment (ACK) frame for the wakeup packet (WUP) may be transmitted based on the newly defined EDCA parameter set to have a higher priority than the legacy EDCA parameter set.

18 is a diagram for describing a method for managing power of a wireless terminal by reflecting a turn-on delay in a wireless LAN system according to another exemplary embodiment.

Referring to FIG. 18, the first wireless terminal 1810 of FIG. 18 may correspond to the first wireless terminal 1510 of FIG. 15. In addition, the main radio module 1811 of FIG. 18 may correspond to the main radio module 1511 of FIG. 15. The second wireless terminal 1820 of FIG. 18 may correspond to the first wireless terminal 1510 of FIG. 15.

In addition, the WUR module 1812 of FIG. 18 may not only support all the operations of the WUR module 1512 of FIG. 15, but also a transmission operation by the WUR module 1812 may be supported.

At the second time point T2, the second wireless terminal 1820 may be understood as a terminal that has acquired a transmission opportunity TXOP.

For operation S1810, the second wireless terminal 1820 may transmit a wakeup packet WUP to the first wireless terminal 1510 at a second time point T2. The wakeup packet WUP may be received via the WUR module 1812 in an activated state.

The wakeup packet WUP includes a reception address (RA) information for indicating a reception terminal of the wakeup packet WUP and a transmission opportunity TXOP obtained by the second wireless terminal 1820. Duration information (for example, T1 to T4 of FIG. 18) may be included.

For example, the first wireless terminal 1810 of FIG. 18 may be indicated by the reception address RA information of the wakeup packet WUP. That is, the first wireless terminal 1810 may demodulate all of the wakeup packets WUP.

The first wireless terminal 1810 may acquire duration information (eg, T1 to T4 of FIG. 18) for a transmission opportunity TXOP included in the wakeup packet WUP. Duration information for the transmission opportunity (TXOP) shown in FIG. 18 is just an example, and it will be understood that the other embodiments are not limited thereto.

For example, the duration information for the transmission opportunity (TXOP) is a time interval (for example, T2 to T4) excluding the time (T1 to T2) required for the backoff procedure by the second wireless terminal 1820. Can be set to indicate.

The other wireless terminal (not shown) that receives the wakeup packet WUP from the first wireless terminal 1810 is duration information for the transmission opportunity TXOP regardless of the reception address RA information of the wakeup packet WUP. (For example, T1 to T4 in FIG. 18) can be obtained.

In addition, another wireless terminal (not shown) not indicated by the reception address RA information of the wake-up packet WUP is NAV according to the duration information (for example, T1 to T4 in FIG. 18) for the transmission opportunity TXOP. Can be set.

As mentioned with reference to FIG. 14, the manner of transmitting the wakeup packet (WUP) may vary. For example, the wakeup packet WUP may be transmitted based on the same EDCA parameter set as the data packet.

For operation S1820, the first wireless terminal 1810 may transmit a wake-up signal for instructing the main radio module 1811 to enter the activated state to the main radio module 1811.

For example, after a time point T2 ′ where reception of the wakeup packet WUP is completed, the wakeup signal may be transmitted to the main radio module 1811.

In the present specification, the turn-on delay TOD, which is a time taken for the main radio module 1811 to enter the activated state according to the wake-up signal, may be longer than the SIFS.

As shown in FIG. 18, the end time of the turn-on delay TOD from the reception time T2 ′ of the wake-up signal is later than the end T4 of the transmission opportunity TXOP obtained by the second wireless terminal 1820. It may be a time point.

At a time point T3 after a predetermined time (eg, SIFS) has elapsed from the reception completion time point T2 of the wakeup packet WUP, the first wireless terminal 1810 responds to the first message in response to the wakeup packet WUP. A reply packet can be sent. In this case, the first response packet may be transmitted during the third period T3 ˜ T3 ′ through the WUR module 1812.

In operation S1840, the main radio module 1811 may enter an active state capable of receiving a packet for the first wireless terminal 1810 from the second wireless terminal 1820.

At a fifth time point T5, the second wireless terminal 1820 may be understood as a terminal that acquires a transmission opportunity (TXOP).

For operation S1850, the second wireless terminal 1820 may transmit a buffered data packet for the first wireless terminal 1810. The data packet may be transmitted to the first wireless terminal 1810 during the sixth period T6 ˜ T6 ′ of FIG. 18.

In detail, the second wireless terminal 1820 may include duration information (for example, T5 to T8 of FIG. 18) for the obtained transmission opportunity (TXOP) in the data packet. In addition, the data packet for the first wireless terminal 1810 may be received via the main radio module 1811 in an activated state.

Another wireless terminal (eg, 1810) may obtain duration information (eg, T5 to T8 of FIG. 18) for a transmission opportunity (TXOP) included in the wakeup packet (WUP). However, the duration information for the transmission opportunity (TXOP) shown in FIG. 18 is just an example, and it will be understood that the other embodiments are not limited thereto.

For step S1850, at a time point T7 after a predetermined time (eg, SIFS) has elapsed from the transmission completion time point T6 ′ of the data frame, the first wireless terminal 1810 responds to the data packet with a second response packet. May be transmitted to the second wireless terminal 1820.

In addition, a second reply packet for the second wireless terminal 1820 may be transmitted via the main radio module 1811 in an activated state. The second acknowledgment packet may be a packet transmitted without contention with another wireless terminal (eg, 1820).

Although not shown in FIG. 18, the second wireless terminal 1820 receiving the second response packet may truncate the remaining TXOP periods T7 ′ through T8.

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

Referring to FIG. 19, a wireless terminal may be an STA capable of implementing the above-described embodiment and may be an AP or a non-AP STA. 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 1900 includes a processor 1910, a memory 1920, and a radio frequency unit 1930.

The RF unit 1930 may be connected to the processor 1910 to transmit / receive a radio signal.

The processor 1910 may implement the functions, processes, and / or methods proposed herein. For example, the processor 1910 may perform an operation according to the present embodiment described above. The processor 1910 may perform an operation of the AP disclosed in the present embodiment of FIGS. 1 to 18.

The non-AP STA 1950 includes a processor 1960, a memory 1970, and a radio frequency unit 1980.

The RF unit 1980 may be connected to the processor 1960 to transmit / receive a radio signal.

The processor 1960 may implement the functions, processes, and / or methods proposed in the present embodiment. For example, the processor 1960 may be implemented to perform the non-AP STA operation according to the present embodiment described above. The processor 1960 may perform an operation of the non-AP STA disclosed in the present embodiment of FIGS. 1 to 18.

Processors 1910 and 1960 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 memory 1920, 1970 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices. The RF unit 1930 and 1980 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 is stored in the memory 1920, 1970 and can be executed by the processor 1910, 1960. The memories 1920 and 1970 may be internal or external to the processors 1910 and 1960, and may be connected to the processors 1910 and 1960 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 (17)

In the method for managing the power of the wireless terminal in a wireless LAN system, A first wireless terminal comprising a main radio module in a deactivation state and a wake-up receiver (WUR) module for waking up the main radio module. Transmits a wake-up packet instructing to enter an activated state, wherein the wake-up packet is the same set of Enhanced Distributed Channel Access (EDCA) parameters as the data packet to be transmitted by the second wireless terminal; Wherein the wakeup packet includes a payload modulated according to an on-off keying (OOK) technique for the WUR module; Receiving, by the second wireless terminal, a first acknowledgment packet to the first wireless terminal informing of successful reception of the wakeup packet; And Sending, by the second wireless terminal, the data packet to the first wireless terminal after receiving the first reply packet. According to claim 1, When a turn-on delay elapses after the reception of the wake-up packet, the main radio module enters the activation state from the deactivation state, The turn-on delay is a time longer than a short inter-frame space (SIFS). The method of claim 2, The first acknowledgment packet is transmitted based on the main radio module of the first wireless terminal acquiring a first channel access through a first channel contention with the second wireless terminal, Wherein the data packet is transmitted by the second wireless terminal acquiring a second channel access via a second channel contention with the first wireless terminal. The method of claim 3, wherein Information about a duration of a transmit opportunity for the second channel access is included in the data packet. The method of claim 2, And receiving, by the second wireless terminal, a second acknowledgment packet indicating a successful reception of the data packet, wherein the second acknowledgment packet is received if the SIFS has elapsed since the reception of the data packet. According to claim 1, The main radio module includes a first receiver for receiving the data packet and a first transmitter for transmitting the first response packet; The WUR module includes a second receiver implemented based on an envelope detector for detecting an envelope of the wakeup packet. According to claim 1, The data packet is included in a transmission queue corresponding to a primary access category determined internally by the second wireless terminal from among first to fourth access categories for the second wireless terminal, The data packet includes receive address information indicating the first wireless terminal. The method of claim 7, wherein The EDCA parameter set is an arbitration inter-frame space (AIFS) which is a preset time for the transmission queue corresponding to the primary access category, and a minimum contention window for an initial value set in a backoff counter of the second wireless terminal. (Counter Window) value (CWmin) and the maximum contention window value (CWmax) for the threshold set in the backoff counter. According to claim 1, If the main radio module is in the deactivated state, the first wireless terminal does not receive a beacon frame periodically transmitted by the second wireless terminal, If the main radio module is in the active state, the first radio terminal transmits the first response packet to the second radio terminal based on the main radio module, And if the main radio module is in the active state, the first wireless terminal receives the data packet transmitted by the second wireless terminal based on the main radio module. According to claim 1, The payload is based on an ON signal determined as a 1 bit ON signal by the WUR module and an OFF signal determined as a 1 bit OFF signal by the WUR module. How it is implemented. The method of claim 10, The on signal is obtained by performing an Inverse Fast Fourier Transform (IFFT) on N2 subcarriers of the N1 subcarriers corresponding to the first channel band of the wakeup packet, and a sequence preset to the N2 subcarriers. How it applies. The method of claim 11, wherein The first channel band is 20 MHz, the N1 subcarriers are 64 subcarriers, the N2 subcarriers are 13 consecutive subcarriers, the preset sequence is a 13-bit sequence, and the wakeup packet The subcarrier spacing applied is 312.5 kHz. The method of claim 12, And a coefficient corresponding to the DC subcarrier in the 13-bit sequence is '0' and the remaining coefficients are set to '1' or '-1'. The method of claim 10, The on signal and the off signal are transmitted based on a 4.06 MHz band. According to claim 1, The data packet includes N4 subcarriers for protecting the left band of N3 subcarriers corresponding to the second channel band of the data packet, N5 subcarriers for protecting the right band, and DC subcarrier corresponding to the DC frequency. The method is transmitted based on N6 subcarriers except for. The method of claim 15, The second channel band is 20MHz, the N3 subcarriers are 64 subcarriers, the N4 subcarriers are four consecutive subcarriers, the subcarriers of N5 are three consecutive subcarriers, and the N6 Subcarriers are 56 consecutive subcarriers. A second wireless terminal using a method for managing power of a first wireless terminal including a main radio module and a wake-up receiver (WUR) module for waking the main radio module in a WLAN system. The second wireless terminal, A transceiver for transmitting and receiving a radio signal; And Including a processor coupled to the transceiver, The main radio module is in a deactivation state, The processor, And implement a wake-up packet instructing the main radio module to enter an activated state, wherein the wake-up packet is an EDCA (same as a data packet to be transmitted by the second wireless terminal). Is transmitted based on an enhanced distributed channel access parameter set, the wakeup packet includes a payload modulated according to an on-off keying (OOK) scheme for the WUR module, Is configured to receive a first acknowledgment packet to the first wireless terminal informing of successful receipt of the wakeup packet, And transmit the data packet to the first wireless terminal after receiving the first reply packet.

Images