WO2016199999A1 - Transmission and reception apparatus and method for wireless communication system - Google Patents

Abstract

An embodiment of the present invention may provide a method for transmitting data by a station (STA) device in a wireless LAN (WLAN) system, the method comprising the steps of: generating a physical protocol data unit (PPDU) including a physical preamble and a data field; and transmitting the PPDU, wherein a transmission channel for the PPDU comprises a plurality of resource units and a plurality of left over tones in the frequency domain, and the plurality of left over tones are located between the plurality of resource units in the frequency domain on the basis of a tone plan for each channel.

Description

Transmission and reception apparatus and method of wireless communication system

The present disclosure relates to a wireless communication system, and more particularly, to a method of arranging resource units and left over tones in a frequency domain, and a STA (Station) apparatus for performing the same in a wireless communication system.

Wi-Fi is a Wireless Local Area Network (WLAN) technology that allows devices to access the Internet in the 2.4 GHz, 5 GHz, or 6 GHz frequency bands.

WLANs are based on the Institute of Electrical and Electronic Engineers (IEEE) 802.11 standard. The Wireless Next Generation Standing Committee (WNG SC) of IEEE 802.11 is an ad hoc committee that considers the next generation wireless local area network (WLAN) in the medium to long term.

IEEE 802.11n aims to increase the speed and reliability of networks and to extend the operating range of wireless networks. More specifically, IEEE 802.11n supports High Throughput (HT), which provides up to 600 Mbps data rate, and also supports both transmitter and receiver to minimize transmission errors and optimize data rates. It is based on Multiple Inputs and Multiple Outputs (MIMO) technology using multiple antennas.

As the popularity of WLAN and the applications diversify using it, the next generation WLAN system supporting Very High Throughput (VHT) is the next version of the IEEE 802.11n WLAN system. IEEE 802.11ac supports data processing speeds of 1 Gbps and higher via 80 MHz bandwidth transmission and / or higher bandwidth transmission (eg 160 MHz) and operates primarily in the 5 GHz band.

Recently, there is a need for a new WLAN system to support higher throughput than the data throughput supported by IEEE 802.11ac.

The scope of IEEE 802.11ax, often discussed in the next-generation WLAN study group called IEEE 802.11ax or High Efficiency (HEW) WLAN, is: 1) 802.11 physical layer and MAC in the 2.4 GHz and 5 GHz bands. (medium access control) layer enhancement, 2) spectral efficiency and area throughput improvement, 3) environments with interference sources, dense heterogeneous network environments, and high user loads. Such as improving performance in real indoor environments and outdoor environments, such as the environment.

Scenarios considered mainly in IEEE 802.11ax are dense environments with many access points (APs) and stations (STAs), and IEEE 802.11ax discusses spectral efficiency and area throughput improvement in such a situation. . In particular, there is an interest in improving the performance of the indoor environment as well as the outdoor environment, which is not much considered in the existing WLAN.

In IEEE 802.11ax, we are interested in scenarios such as wireless office, smart home, stadium, hotspot, and building / apartment. There is a discussion about improving system performance in dense environments with many STAs.

In the future, IEEE 802.11ax improves system performance in outdoor basic service set (OBSS) environment, outdoor environment performance, and cellular offloading rather than single link performance in one basic service set (BSS). Discussion is expected to be active. The directionality of IEEE 802.11ax means that next-generation WLANs will increasingly have a technology range similar to that of mobile communication. Considering the situation where mobile communication and WLAN technology are recently discussed in the small cell and direct-to-direct communication area, the technical and business of next-generation WLAN and mobile communication based on IEEE 802.11ax Convergence is expected to become more active.

As described above, a new frame format and numerology for the 802.11ax system, which is a next generation wireless LAN system, are actively discussed.

In particular, it is expected to apply an increased FFT size to a given system bandwidth to improve the throughput of the system or to improve the robustness against inter-symbol interference (ISI) in outdoor environments. In addition, the multi-user transmission scheme proposed in the existing 802.11ac system is extended to the uplink situation, and the discussion on the introduction of the OFDMA transmission scheme is also accompanied.

In particular, discussions on the tone plan to be used in the OFDMA transmission scheme are actively underway, and it is important to discuss in which tone size units tones located in a given bandwidth are used as resource units. Furthermore, it is important to discuss where to place the remaining tones (eg guard tones, direct current (DC) tones, left over tones, etc.) except for tones separated as resource units. .

In order to solve the above technical problem, an STA apparatus and a data transmission method of the STA apparatus of the WLAN system according to an embodiment of the present invention are proposed.

A data transmission method of a STA (Station) device in a wireless LAN (WLAN) system, the method comprising: generating a physical protocol data unit (PPDU) including a physical preamble and a data field; Transmitting the PPDU; The transmission channel of the PPDU includes a plurality of resource units and a plurality of left over tones in the frequency domain, wherein the plurality of left over tones are based on a tone plan for each channel. It may be located between the plurality of resource units in the frequency domain.

In addition, when the transmission channel is a 20 MHz channel, the plurality of left over tones may be configured of four left over tones.

In addition, when the plurality of resource units include nine resource units each composed of 26-tones, a first left over tone is between a second and a third resource unit, and a second left over tone is a seventh and eighth. It can be located between resource units.

Further, when the plurality of resource units include one resource unit consisting of 26-tones and four resource units each consisting of 52-tones, the first left over tone is between the first and second resource units, and The second left over tone may be located between the fourth and fifth resource units.

Further, the first, second, fourth, and fifth resource units may be resource units each configured of the 52-tones, and the third resource unit may be one resource unit of the 26-tones.

In addition, seven DC tones may be located in the center frequency region of the 20 MHz channel.

Further, when the transmission channel is a 40 MHz channel and the plurality of resource units include 18 resource units each configured of 26-tones, the plurality of left over tones are composed of 16 left over tones and the plurality of left over tones When the resource units include two resource units each composed of the 26-tones and eight resource units each consisting of 52-tones, the plurality of left over tones are composed of the sixteen left over tones, and the When a plurality of resource units include two resource units each configured of the 26-tones and four resource units each consisting of 106-tones, the plurality of left over tones may be configured of eight left over tones. .

Further, when the plurality of resource units include 18 resource units each configured of the 26-tones, the first and second left over tones are between the second and third resource units, and the third left over tones are fourth And between the fifth resource unit, the fourth left over tone is between the fifth and sixth resource units, the fifth and sixth left over tones are between the seventh and eighth resource units, and the seventh and eighth left over tones are Between the ninth and tenth resource units, the ninth and tenth left over tones between the eleventh and twelfth resource units, the eleventh left over tones between the thirteenth and fourteenth resource units, and the twelfth left over tone is the 14 Between the 1 st and 15 th resource units, and the 13 th and 14 left over tones may be located between the 16 th and 17 th resource units.

In addition, when the plurality of resource units include two resource units each composed of the 26-tones and eight resource units each consisting of the 52-tones, the first and second left over tones are first and second. Between a fourth resource unit, a third left over tone between the second and third resource units, a fourth left over tone between the third and fourth resource units, and a fifth and sixth left over tone between the fourth and Between the fifth resource unit, the seventh and eighth left over tone is between the fifth and sixth resource units, the ninth and tenth left over tones are between the sixth and seventh resource units, and the eleventh left over tone is Between the seventh and eighth resource units, a twelfth left over tone may be located between the eighth and ninth resource units, and a thirteenth and fourteen left over tones may be located between the ninth and tenth resource units.

Further, the first, second, fourth, fifth, sixth, seventh, ninth, and tenth resource units are resource units each composed of the 52-tones, and the third and eighth resource units The resource units may be configured in the 26-tone, respectively.

In addition, when the plurality of resource units include two resource units each composed of the 26-tones and four resource units each consisting of the 106-tones, the first left over tone is the first and second resource units. Between, the second left over tone is between the second and third resource units, the third and fourth left over tones are between the third and fourth resource units, and the fifth left over tone is the fourth and fifth resources. Between units, and a sixth left over tone may be located between the fifth and sixth resource units.

Further, the first, third, fourth, and sixth resource units may be resource units composed of the 106-tones, respectively, and the second and fifth resource units may be resource units composed of the 26-tones, respectively. .

In addition, five DC tones may be located in the center frequency region of the 40 MHz channel.

In addition, the tone plan of the 40 MHz channel may be repeatedly applied to the tone plan of the 80 MHz channel.

In addition, seven DC tones may be located in the center frequency region of the 80 MHz channel.

An STA (Station) apparatus of a wireless LAN (WLAN) system according to another embodiment of the present invention, comprising: a radio frequency (RF) unit for transmitting and receiving a radio signal; And a processor for controlling the RF unit; The processor may include a physical protocol data unit (PPDU) including a physical preamble and a data field, and transmit the PPDU using the RF unit. The transmission channel includes a plurality of resource units and a plurality of left over tones in the frequency domain, wherein the plurality of left over tones are configured for the plurality of resources in the frequency domain based on a channel-specific tone plan. It can be located between units.

The above-described embodiments may be selectively applied or combined according to effects and purposes.

According to an embodiment of the present invention, as the number of DC tones located in the frequency center region of the channel increases, the energy of the center frequency region is increased to have a robust performance in measuring the CFO. Furthermore, it also has an advantageous effect in terms of peak-to-average power ratio (PAPR) of the STF sequence.

Furthermore, according to one embodiment of the invention, the interference between the resource units due to at least one left over tone located between the resource units (26-tone resource unit, 52-tone resource unit, 106-tone resource unit) This has the effect of shrinking.

In addition, according to an embodiment of the present invention, when using the HE STF of the 2x FFT size, it is possible to ensure that the pilot tone is even tone.

Other effects of the present invention will be further described in the following embodiments.

1 is a diagram illustrating an example of an IEEE 802.11 system to which the present invention can be applied.

2 is a diagram illustrating a structure of a layer architecture of an IEEE 802.11 system to which the present invention may be applied.

3 illustrates a non-HT format PPDU and a HT format PPDU of a wireless communication system to which the present invention can be applied.

4 illustrates a VHT format PPDU format of a wireless communication system to which the present invention can be applied.

5 is a diagram illustrating a constellation for distinguishing a format of a PPDU of a wireless communication system to which the present invention can be applied.

6 illustrates a MAC frame format of an IEEE 802.11 system to which the present invention can be applied.

FIG. 7 is a diagram illustrating a Frame Control field in a MAC frame in a wireless communication system to which the present invention can be applied.

FIG. 8 illustrates the HT format of the HT Control field in the MAC frame according to FIG. 6.

9 illustrates the VHT format of the HT Control field in a wireless communication system to which the present invention can be applied.

FIG. 10 is a diagram illustrating a general link setup procedure in a wireless communication system to which the present invention can be applied.

11 is a diagram for explaining an arbitrary backoff period and a frame transmission procedure in a wireless communication system to which the present invention can be applied.

12 is a diagram for describing a hidden node and an exposed node in a wireless communication system to which the present invention can be applied.

13 is a view for explaining the RTS and CTS in a wireless communication system to which the present invention can be applied.

14 illustrates a tone plan of a 20 MHz channel according to the first embodiment of the present invention.

15 illustrates an index of a leftover tone according to an embodiment of the present invention.

16 illustrates a tone plan of a 20 MHz channel according to a second embodiment of the present invention.

17 illustrates a tone plan of a 20 MHz channel according to a third embodiment of the present invention.

18 illustrates a tone plan of a 40 MHz channel according to a fourth embodiment of the present invention.

19 illustrates a tone plan of a 40 MHz channel according to a fifth embodiment of the present invention.

20 illustrates a tone plan of a 40 MHz channel according to a sixth embodiment of the present invention.

21 illustrates a tone plan of a 40 MHz channel according to a seventh embodiment of the present invention.

22 illustrates a tone plan of a 40 MHz channel according to an eighth embodiment of the present invention.

FIG. 23 illustrates a tone plan of an 80 MHz channel according to a ninth embodiment of the present invention.

24 illustrates a tone plan of an 80 MHz channel according to a tenth embodiment of the present invention.

25 illustrates a tone plan of an 80 MHz channel according to an eleventh embodiment of the present invention.

FIG. 26 illustrates a tone plan of an 80 MHz channel according to a twelfth embodiment of the present invention.

27 shows a tone plan of an 80 MHz channel according to a thirteenth embodiment of the present invention.

28 illustrates a tone plan of an 80 MHz channel according to a fourteenth embodiment of the present invention.

29 is a flowchart illustrating a data transmission method of an STA apparatus according to an embodiment of the present invention.

30 is a block diagram of each STA apparatus according to an embodiment of the present invention.

31 illustrates a portion of a STA device in more detail according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, one of ordinary skill in the art appreciates that the present invention may be practiced without these specific details.

In some instances, well-known structures and devices may be omitted or shown in block diagram form centering on the core functions of the structures and devices in order to avoid obscuring the concepts of the present invention.

Specific terms used in the following description are provided to help the understanding of the present invention, and the use of such specific terms may be changed to other forms without departing from the technical spirit of the present invention.

The following techniques are code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and NOMA It can be used in various radio access systems such as non-orthogonal multiple access. CDMA may be implemented by a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as global system for mobile communications (GSM) / general packet radio service (GPRS) / enhanced data rates for GSM evolution (EDGE). OFDMA may be implemented with wireless technologies such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, evolved UTRA (E-UTRA), and the like. UTRA is part of a universal mobile telecommunications system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is a part of evolved UMTS (E-UMTS) using E-UTRA, and employs OFDMA in downlink and SC-FDMA in uplink. LTE-A (advanced) is the evolution of 3GPP LTE.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802, 3GPP and 3GPP2. That is, steps or parts which are not described to clearly reveal the technical spirit of the present invention among the embodiments of the present invention may be supported by the above documents. In addition, all terms disclosed in the present document can be described by the above standard document.

For clarity, the following description focuses on IEEE 802.11 systems, but the technical features of the present invention are not limited thereto.

System general

1 is a diagram illustrating an example of an IEEE 802.11 system to which the present invention can be applied.

The IEEE 802.11 structure may be composed of a plurality of components, and a wireless communication system supporting a station (STA) mobility that is transparent to a higher layer may be provided by their interaction. . A basic service set (BSS) may correspond to a basic building block in an IEEE 802.11 system.

In FIG. 1, there are three BSSs (BSS 1 to BSS 3) and two STAs are included as members of each BSS (STA 1 and STA 2 are included in BSS 1, and STA 3 and STA 4 are BSS 2. Included in, and STA 5 and STA 6 are included in BSS 3) by way of example.

In FIG. 1, an ellipse representing a BSS may be understood to represent a coverage area where STAs included in the BSS maintain communication. This area may be referred to as a basic service area (BSA). When the STA moves out of the BSA, the STA cannot directly communicate with other STAs in the BSA.

The most basic type of BSS in an IEEE 802.11 system is an independent BSS (IBSS). For example, the IBSS may have a minimal form consisting of only two STAs. In addition, BSS 3 of FIG. 1, which is the simplest form and other components are omitted, may correspond to a representative example of the IBSS. This configuration is possible when STAs can communicate directly. In addition, this type of LAN may not be configured in advance, but may be configured when a LAN is required, which may be referred to as an ad-hoc network.

The membership of the STA in the BSS may be dynamically changed by turning the STA on or off, the STA entering or exiting the BSS region, or the like. In order to become a member of the BSS, the STA may join the BSS using a synchronization process. In order to access all services of the BSS infrastructure, the STA must be associated with the BSS. This association may be set up dynamically and may include the use of a Distribution System Service (DSS).

The direct STA-to-STA distance in an 802.11 system may be limited by physical layer (PHY) performance. In some cases, this distance limit may be sufficient, but in some cases, communication between STAs over longer distances may be required. A distribution system (DS) may be configured to support extended coverage.

DS refers to a structure in which BSSs are interconnected. Specifically, instead of the BSS independently as shown in FIG. 1, the BSS may exist as an extended type component of a network composed of a plurality of BSSs.

DS is a logical concept and can be specified by the characteristics of the Distribution System Medium (DSM). In this regard, the IEEE 802.11 standard logically distinguishes between wireless medium (WM) and distribution system medium (DSM). Each logical medium is used for a different purpose and is used by different components. The definition of the IEEE 802.11 standard does not limit these media to the same or to different ones. In this way, the plurality of media are logically different, and thus the flexibility of the structure of the IEEE 802.11 system (DS structure or other network structure) can be described. That is, the IEEE 802.11 system structure can be implemented in various ways, the corresponding system structure can be specified independently by the physical characteristics of each implementation.

The DS may support mobile devices by providing seamless integration of multiple BSSs and providing logical services for handling addresses to destinations.

The AP means an entity that enables access to the DS through the WM to the associated STAs and has STA functionality. Data movement between the BSS and the DS may be performed through the AP. For example, STA 2 and STA 3 illustrated in FIG. 1 have a functionality of STA, and provide a function of allowing associated STAs STA 1 and STA 4 to access the DS. In addition, since all APs basically correspond to STAs, all APs are addressable entities. The address used by the AP for communication on the WM and the address used by the AP for communication on the DSM need not necessarily be the same.

Data transmitted from one of the STAs associated with an AP to the STA address of that AP may always be received at an uncontrolled port and processed by an IEEE 802.1X port access entity. In addition, when a controlled port is authenticated, transmission data (or frame) may be transmitted to the DS.

A wireless network of arbitrary size and complexity may be composed of DS and BSSs. In an IEEE 802.11 system, this type of network is referred to as an extended service set (ESS) network. The ESS may correspond to a set of BSSs connected to one DS. However, the ESS does not include a DS. The ESS network is characterized by what appears to be an IBSS network at the Logical Link Control (LLC) layer. STAs included in the ESS may communicate with each other, and mobile STAs may move from one BSS to another BSS (within the same ESS) transparently to the LLC.

In the IEEE 802.11 system, nothing is assumed about the relative physical location of the BSSs in FIG. 1, and all of the following forms are possible.

Specifically, BSSs can be partially overlapped, which is the form generally used to provide continuous coverage. Also, the BSSs may not be physically connected, and logically there is no limit to the distance between the BSSs. In addition, the BSSs can be located at the same physical location, which can be used to provide redundancy. In addition, one (or more) IBSS or ESS networks may be physically present in the same space as one or more ESS networks. This may be necessary if the ad-hoc network is operating at the location of the ESS network, if the IEEE 802.11 networks are physically overlapped by different organizations, or if two or more different access and security policies are required at the same location. It may correspond to an ESS network type in a case.

In a WLAN system, an STA is a device that operates according to Medium Access Control (MAC) / PHY regulations of IEEE 802.11. As long as the function of the STA is not distinguished from the AP individually, the STA may include an AP STA and a non-AP STA. However, when communication is performed between the STA and the AP, the STA may be understood as a non-AP STA. In the example of FIG. 1, STA 1, STA 4, STA 5, and STA 6 correspond to non-AP STAs, and STA 2 and STA 3 correspond to AP STAs.

Non-AP STAs generally correspond to devices that users directly handle, such as laptop computers and mobile phones. In the following description, a non-AP STA includes a wireless device, a terminal, a user equipment (UE), a mobile station (MS), a mobile terminal, and a wireless terminal. ), A wireless transmit / receive unit (WTRU), a network interface device (network interface device), a machine-type communication (MTC) device, a machine-to-machine (M2M) device, or the like.

In addition, the AP is a base station (BS), Node-B (Node-B), evolved Node-B (eNB), and Base Transceiver System (BTS) in other wireless communication fields. , A concept corresponding to a femto base station (Femto BS).

Hereinafter, in the present specification, downlink (DL) means communication from the AP to the non-AP STA, and uplink (UL) means communication from the non-AP STA to the AP. In downlink, the transmitter may be part of an AP and the receiver may be part of a non-AP STA. In uplink, a transmitter may be part of a non-AP STA and a receiver may be part of an AP.

2 is a diagram illustrating a structure of a layer architecture of an IEEE 802.11 system to which the present invention may be applied.

Referring to FIG. 2, the layer architecture of the IEEE 802.11 system may include a MAC sublayer and a PHY sublayer.

The PHY sublayer may be divided into a Physical Layer Convergence Procedure (PLCP) entity and a Physical Medium Dependent (PMD) entity. In this case, the PLCP entity plays a role of connecting a data frame with a MAC sublayer, and the PMD entity plays a role of wirelessly transmitting and receiving data with two or more STAs.

Both the MAC sublayer and the PHY sublayer may include a management entity, which may be referred to as a MAC sublayer management entity (MLME) and a PHY sublayer management entity (PLME), respectively. have. These management entities provide layer management service interfaces through the operation of layer management functions. The MLME may be connected to the PLME to perform management operations of the MAC sublayer, and likewise the PLME may be connected to the MLME to perform management operations of the PHY sublayer.

In order to provide correct MAC operation, a Station Management Entity (SME) may be present in each STA. The SME is a management entity independent of each layer. The SME collects layer-based state information from MLME and PLME or sets values of specific parameters of each layer. The SME can perform these functions on behalf of general system management entities and implement standard management protocols.

MLME, PLME and SME can interact in a variety of ways based on primitives. Specifically, the XX-GET.request primitive is used to request the value of a Management Information Base attribute (MIB attribute), and the XX-GET.confirm primitive, if the status is 'SUCCESS', returns the value of that MIB attribute. Otherwise, it returns with an error indication in the status field. The XX-SET.request primitive is used to request that a specified MIB attribute be set to a given value. If the MIB attribute is meant for a particular action, this request requests the execution of that particular action. And, if the state is 'SUCCESS' XX-SET.confirm primitive, it means that the specified MIB attribute is set to the requested value. In other cases, the status field indicates an error condition. If this MIB attribute means a specific operation, this primitive can confirm that the operation was performed.

The operation in each sublayer is briefly described as follows.

The MAC sublayer includes a MAC header and a frame check sequence (FCS) in a MAC Service Data Unit (MSDU) or a fragment of an MSDU received from an upper layer (eg, an LLC layer). A sequence is attached to generate one or more MAC Protocol Data Units (MPDUs). The generated MPDU is delivered to the PHY sublayer.

When an aggregated MSDU (A-MSDU) scheme is used, a plurality of MSDUs may be merged into a single A-MSDU (aggregated MSDU). The MSDU merging operation may be performed at the MAC upper layer. The A-MSDU is delivered to the PHY sublayer as a single MPDU (if not fragmented).

The PHY sublayer generates a physical protocol data unit (PPDU) by adding an additional field including information required by a physical layer transceiver to a physical service data unit (PSDU) received from the MAC sublayer. . PPDUs are transmitted over wireless media.

The PSDU is substantially the same as the MPDU since the PHY sublayer is received from the MAC sublayer and the MPDU is transmitted by the MAC sublayer to the PHY sublayer.

When an aggregated MPDU (A-MPDU) scheme is used, a plurality of MPDUs (where each MPDU may carry an A-MSDU) may be merged into a single A-MPDU. The MPDU merging operation may be performed at the MAC lower layer. A-MPDUs may be merged with various types of MPDUs (eg, QoS data, Acknowledge (ACK), Block ACK (BlockAck), etc.). The PHY sublayer receives the A-MPDU as a single PSDU from the MAC sublayer. That is, the PSDU is composed of a plurality of MPDUs. Thus, A-MPDUs are transmitted over the wireless medium in a single PPDU.

PPDU Physical Protocol Data Unit Format

Physical Protocol Data Unit (PPDU) refers to a data block generated in the physical layer. Hereinafter, a PPDU format will be described based on an IEEE 802.11 WLAN system to which the present invention can be applied.

3 illustrates a non-HT format PPDU and a HT format PPDU of a wireless communication system to which the present invention can be applied.

3A illustrates a non-HT format PPDU for supporting an IEEE 802.11a / g system. Non-HT PPDUs may also be referred to as legacy PPDUs.

Referring to (a) of FIG. 3, the non-HT format PPDU includes an L-STF (Legacy (or Non-HT) Short Training field), L-LTF (Legacy (or, Non-HT) Long Training field) and It includes a legacy format preamble and a data field composed of an L-SIG (Legacy (or Non-HT) SIGNAL) field.

The L-STF may include a short training orthogonal frequency division multiplexing symbol (OFDM) symbol. L-STF can be used for frame timing acquisition, automatic gain control (AGC), diversity detection, and coarse frequency / time synchronization. .

The L-LTF may include a long training orthogonal frequency division multiplexing symbol. L-LTF may be used for fine frequency / time synchronization and channel estimation.

The L-SIG field may be used to transmit control information for demodulation and decoding of the data field. The L-SIG field may include information about a data rate and a data length.

3B illustrates an HT-mixed format PPDU (HTDU) for supporting both an IEEE 802.11n system and an IEEE 802.11a / g system.

Referring to FIG. 3B, the HT mixed format PPDU includes a legacy format preamble including an L-STF, L-LTF, and L-SIG fields, an HT-SIG (HT-Signal) field, and an HT-STF (HT Short). Training field), HT-formatted preamble and data field including HT-LTF (HT Long Training field).

Since the L-STF, L-LTF, and L-SIG fields mean legacy fields for backward compatibility, they are the same as non-HT formats from L-STF to L-SIG fields. Even if the L-STA receives the HT mixed PPDU, the L-STA may interpret the data field through the L-LTF, L-LTF and L-SIG fields. However, the L-LTF may further include information for channel estimation that the HT-STA performs to receive the HT mixed PPDU and demodulate the L-SIG field and the HT-SIG field.

The HT-STA may know that it is an HT-mixed format PPDU using the HT-SIG field following the legacy field, and may decode the data field based on the HT-STA.

The HT-LTF field may be used for channel estimation for demodulation of the data field. Since IEEE 802.11n supports Single-User Multi-Input and Multi-Output (SU-MIMO), a plurality of HT-LTF fields may be configured for channel estimation for each data field transmitted in a plurality of spatial streams.

The HT-LTF field includes data HT-LTF used for channel estimation for spatial streams and extension HT-LTF (additional used for full channel sounding). It can be configured as. Accordingly, the plurality of HT-LTFs may be equal to or greater than the number of spatial streams transmitted.

In the HT-mixed format PPDU, the L-STF, L-LTF, and L-SIG fields are transmitted first in order to receive the L-STA and acquire data. Thereafter, the HT-SIG field is transmitted for demodulation and decoding of data transmitted for the HT-STA.

The HT-SIG field is transmitted without performing beamforming so that the L-STA and HT-STA can receive the corresponding PPDU to acquire data, and then the HT-STF, HT-LTF and data fields transmitted are precoded. Wireless signal transmission is performed through. In this case, the HT-STF field is transmitted to allow the STA to perform precoding to take into account the variable power due to precoding, and then the plurality of HT-LTF and data fields after that.

3 (c) illustrates an HT-GF format PPDU (HT-GF) for supporting only an IEEE 802.11n system.

Referring to FIG. 3C, the HT-GF format PPDU includes HT-GF-STF, HT-LTF1, HT-SIG field, a plurality of HT-LTF2, and a data field.

HT-GF-STF is used for frame timing acquisition and AGC.

HT-LTF1 is used for channel estimation.

The HT-SIG field is used for demodulation and decoding of the data field.

HT-LTF2 is used for channel estimation for demodulation of data fields. Similarly, since HT-STA uses SU-MIMO, channel estimation is required for each data field transmitted in a plurality of spatial streams, and thus HT-LTF2 may be configured in plural.

The plurality of HT-LTF2 may be configured of a plurality of Data HT-LTF and a plurality of extended HT-LTF similarly to the HT-LTF field of the HT mixed PPDU.

In (a) to (c) of FIG. 3, the data field is a payload, and includes a service field, a SERVICE field, a scrambled PSDU field, tail bits, and padding bits. It may include. All bits of the data field are scrambled.

3D illustrates a service field included in a data field. The service field has 16 bits. Each bit is assigned from 0 to 15, and transmitted sequentially from bit 0. Bits 0 to 6 are set to 0 and used to synchronize the descrambler in the receiver.

The IEEE 802.11ac WLAN system supports downlink multi-user multiple input multiple output (MU-MIMO) transmission in which a plurality of STAs simultaneously access a channel in order to efficiently use a wireless channel. According to the MU-MIMO transmission scheme, the AP may simultaneously transmit packets to one or more STAs that are paired with MIMO.

DL MU transmission (downlink multi-user transmission) refers to a technology in which an AP transmits a PPDU to a plurality of non-AP STAs through the same time resource through one or more antennas.

Hereinafter, the MU PPDU refers to a PPDU that delivers one or more PSDUs for one or more STAs using MU-MIMO technology or OFDMA technology. The SU PPDU means a PPDU having a format in which only one PSDU can be delivered or in which no PSDU exists.

The size of control information transmitted to the STA may be relatively large compared to the size of 802.11n control information for MU-MIMO transmission. An example of control information additionally required for MU-MIMO support includes information indicating the number of spatial streams received by each STA, information related to modulation and coding of data transmitted to each STA, and the like. Can be.

Therefore, when MU-MIMO transmission is performed to simultaneously provide data services to a plurality of STAs, the size of transmitted control information may be increased according to the number of receiving STAs.

In order to efficiently transmit the increased size of the control information, a plurality of control information required for MU-MIMO transmission is required separately for common control information common to all STAs and specific STAs. The data may be transmitted by being divided into two types of information of dedicated control information.

4 illustrates a VHT format PPDU format of a wireless communication system to which the present invention can be applied.

4 illustrates a VHT format PPDU (VHT format PPDU) for supporting an IEEE 802.11ac system.

Referring to FIG. 4, the VHT format PPDU includes a legacy format preamble including L-STF, L-LTF, and L-SIG fields, a VHT-SIG-A (VHT-Signal-A) field, and VHT-STF (VHT Short Training). Field), VHT Long Training Field (VHT-LTF), and VHT-SIG-B (VHT-Signal-B) field.

Since L-STF, L-LTF, and L-SIG indicate legacy fields for backward compatibility, the L-STF to L-SIG fields are the same as non-HT formats. However, the L-LTF may further include information for channel estimation to be performed to demodulate the L-SIG field and the VHT-SIG-A field.

The L-STF, L-LTF, L-SIG field, and VHT-SIG-A field may be repeatedly transmitted in 20 MHz channel units. For example, when a PPDU is transmitted on four 20 MHz channels (i.e. 80 MHz bandwidth), the L-STF, L-LTF, L-SIG field, and VHT-SIG-A field are repeated on every 20 MHz channel. Can be sent.

The VHT-STA may know that it is a VHT format PPDU using the VHT-SIG-A field following the legacy field, and may decode the data field based on the VHT-STA.

In the VHT format PPDU, the L-STF, L-LTF, and L-SIG fields are transmitted first in order to receive the L-STA and acquire data. Thereafter, the VHT-SIG-A field is transmitted for demodulation and decoding of data transmitted for the VHT-STA.

The VHT-SIG-A field is a field for transmitting control information common to the AP and MIMO paired VHT STAs, and may include control information for interpreting the received VHT format PPDU.

The VHT-SIG-A field may include a VHT-SIG-A1 field and a VHT-SIG-A2 field.

The VHT-SIG-A1 field includes information on channel bandwidth (BW) used, whether space time block coding (STBC) is applied, and group identification information for indicating a group of STAs grouped in MU-MIMO. Group ID (Group Identifier), information about the number of space-time streams (NSTS) / Partial AID (Partial Association Identifier) and Transmit power save forbidden information. can do. Here, the Group ID means an identifier assigned to the STA group to be transmitted to support MU-MIMO transmission, and may indicate whether the currently used MIMO transmission method is MU-MIMO or SU-MIMO.

The VHT-SIG-A2 field contains information on whether a short guard interval (GI) is used, forward error correction (FEC) information, information on modulation and coding scheme (MCS) for a single user, and multiple information. Information on the type of channel coding for the user, beamforming-related information, redundancy bits for cyclic redundancy checking (CRC), tail bits of convolutional decoder, and the like. Can be.

VHT-STF is used to improve the performance of AGC estimation in MIMO transmission.

VHT-LTF is used by the VHT-STA to estimate the MIMO channel. Since the VHT WLAN system supports MU-MIMO, the VHT-LTF may be set as many as the number of spatial streams in which a PPDU is transmitted. In addition, if full channel sounding is supported, the number of VHT-LTFs may be greater.

The VHT-SIG-B field includes dedicated control information required for a plurality of MU-MIMO paired VHT-STAs to receive a PPDU and acquire data. Accordingly, the VHT-STA may be designed to decode the VHT-SIG-B only when the common control information included in the VHT-SIG-A field indicates the MU-MIMO transmission currently received. On the other hand, if the common control information indicates that the currently received PPDU is for a single VHT-STA (including SU-MIMO), the STA may be designed not to decode the VHT-SIG-B field.

The VHT-SIG-B field may include information on modulation, encoding, and rate-matching of each VHT-STA. The size of the VHT-SIG-B field may vary depending on the type of MIMO transmission (MU-MIMO or SU-MIMO) and the channel bandwidth used for PPDU transmission.

In order to transmit a PPDU of the same size to STAs paired to an AP in a system supporting MU-MIMO, information indicating a bit size of a data field constituting the PPDU and / or indicating a bit stream size constituting a specific field May be included in the VHT-SIG-A field.

However, the L-SIG field may be used to effectively use the PPDU format. In order to transmit the same size PPDU to all STAs, a length field and a rate field included in the L-SIG field and transmitted may be used to provide necessary information. In this case, since the MAC Protocol Data Unit (MPDU) and / or Aggregate MAC Protocol Data Unit (A-MPDU) are set based on the bytes (or octets) of the MAC layer, additional padding is applied at the physical layer. May be required.

In FIG. 4, the data field is a payload and may include a service field, a scrambled PSDU, tail bits, and padding bits.

Since the formats of various PPDUs are mixed and used as described above, the STA must be able to distinguish the formats of the received PPDUs.

Here, the meaning of distinguishing a PPDU (or meaning of distinguishing a PPDU format) may have various meanings. For example, the meaning of identifying the PPDU may include determining whether the received PPDU is a PPDU that can be decoded (or interpreted) by the STA. In addition, the meaning of distinguishing the PPDU may mean determining whether the received PPDU is a PPDU supported by the STA. In addition, the meaning of distinguishing the PPDU may also be interpreted to mean what information is transmitted through the received PPDU.

This will be described in more detail with reference to the drawings below.

5 is a diagram illustrating a constellation for distinguishing a format of a PPDU of a wireless communication system to which the present invention can be applied.

FIG. 5A illustrates a constellation of an L-SIG field included in a non-HT format PPDU, and FIG. 5B illustrates a phase rotation for HT mixed format PPDU detection. 5C illustrates phase rotation for VHT format PPDU detection.

Constellation of OFDM symbols transmitted after the L-SIG field and the L-SIG field in order for the STA to classify non-HT format PPDUs, HT-GF format PPDUs, HT mixed format PPDUs, and VHT format PPDUs. Phase is used. That is, the STA may distinguish the PPDU format based on the phase of the constellation of the OFDM symbol transmitted after the L-SIG field and / or the L-SIG field of the received PPDU.

Referring to FIG. 5A, binary phase shift keying (BPSK) is used for an OFDM symbol constituting an L-SIG field.

First, in order to distinguish the HT-GF format PPDU, when the first SIG field is detected in the received PPDU, the STA determines whether it is an L-SIG field. That is, the STA attempts to decode based on the constellation as illustrated in (a) of FIG. 5. If the STA fails to decode, it may be determined that the corresponding PPDU is an HT-GF format PPDU.

Next, in order to classify non-HT format PPDUs, HT mixed format PPDUs, and VHT format PPDUs, the phase of the constellation of OFDM symbols transmitted after the L-SIG field may be used. That is, the modulation method of OFDM symbols transmitted after the L-SIG field may be different, and the STA may distinguish the PPDU format based on the modulation method for the field after the L-SIG field of the received PPDU.

Referring to FIG. 5B, in order to distinguish the HT mixed format PPDU, the phase of two OFDM symbols transmitted after the L-SIG field in the HT mixed format PPDU may be used.

More specifically, the phases of OFDM symbol # 1 and OFDM symbol # 2 corresponding to the HT-SIG field transmitted after the L-SIG field in the HT mixed format PPDU are rotated by 90 degrees in the counterclockwise direction. That is, quadrature binary phase shift keying (QBPSK) is used as a modulation method for OFDM symbol # 1 and OFDM symbol # 2. The QBPSK constellation may be a constellation rotated by 90 degrees in a counterclockwise direction based on the BPSK constellation.

The STA attempts to decode the first OFDM symbol and the second OFDM symbol corresponding to the HT-SIG field transmitted after the L-SIG field of the received PPDU based on the properties as shown in FIG. If the STA succeeds in decoding, it is determined that the corresponding PPDU is an HT format PPDU.

Next, in order to distinguish between the non-HT format PPDU and the VHT format PPDU, the phase of the constellation of the OFDM symbol transmitted after the L-SIG field may be used.

Referring to FIG. 5C, in order to classify the VHT format PPDU, the phase of two OFDM symbols transmitted after the L-SIG field in the VHT format PPDU may be used.

More specifically, the phase of the OFDM symbol # 1 corresponding to the VHT-SIG-A field after the L-SIG field in the VHT format PPDU is not rotated, but the phase of the OFDM symbol # 2 is rotated by 90 degrees counterclockwise. . That is, BPSK is used for the modulation method for OFDM symbol # 1 and QBPSK is used for the modulation method for OFDM symbol # 2.

The STA attempts to decode the first OFDM symbol and the second OFDM symbol corresponding to the VHT-SIG field transmitted after the L-SIG field of the received PPDU based on the properties as shown in the example of FIG. If the STA succeeds in decoding, it may be determined that the corresponding PPDU is a VHT format PPDU.

On the other hand, if decoding fails, the STA may determine that the corresponding PPDU is a non-HT format PPDU.

MAC frame format

6 illustrates a MAC frame format of an IEEE 802.11 system to which the present invention can be applied.

Referring to FIG. 6, a MAC frame (ie, an MPDU) includes a MAC header, a frame body, and a frame check sequence (FCS).

MAC Header includes Frame Control field, Duration / ID field, Address 1 field, Address 2 field, Address 3 field, Sequence control It is defined as an area including a Control field, an Address 4 field, a QoS Control field, and an HT Control field.

The Frame Control field includes information on the MAC frame characteristic. A detailed description of the Frame Control field will be given later.

The Duration / ID field may be implemented to have different values depending on the type and subtype of the corresponding MAC frame.

If the type and subtype of the corresponding MAC frame is a PS-Poll frame for power save (PS) operation, the Duration / ID field is an AID (association identifier) of the STA that transmitted the frame. It may be set to include. Otherwise, the Duration / ID field may be set to have a specific duration value according to the type and subtype of the corresponding MAC frame. In addition, when the frame is an MPDU included in an A-MPDU format, the Duration / ID fields included in the MAC header may be set to have the same value.

The Address 1 to Address 4 fields include a BSSID, a source address (SA), a destination address (DA), a transmission address (TA) indicating a transmission STA address, and a reception address indicating a destination STA address (TA). RA: It is used to indicate Receiving Address.

Meanwhile, the address field implemented as a TA field may be set to a bandwidth signaling TA value, in which case, the TA field may indicate that the corresponding MAC frame contains additional information in the scrambling sequence. The bandwidth signaling TA may be represented by the MAC address of the STA transmitting the corresponding MAC frame, but the Individual / Group bit included in the MAC address may be set to a specific value (for example, '1'). Can be.

The Sequence Control field is set to include a sequence number and a fragment number. The sequence number may indicate a sequence number allocated to the corresponding MAC frame. The fragment number may indicate the number of each fragment of the corresponding MAC frame.

The QoS Control field contains information related to QoS. The QoS Control field may be included when indicating a QoS data frame in a subtype subfield.

The HT Control field includes control information related to the HT and / or VHT transmission / reception schemes. The HT Control field is included in the Control Wrapper frame. In addition, it exists in the QoS data frame and the management frame in which the order subfield value is 1.

The frame body is defined as a MAC payload, and data to be transmitted in a higher layer is located, and has a variable size. For example, the maximum MPDU size may be 11454 octets, and the maximum PPDU size may be 5.484 ms.

FCS is defined as a MAC footer and is used for error detection of MAC frames.

The first three fields (Frame Control field, Duration / ID field and Address 1 field) and the last field (FCS field) constitute the minimum frame format and are present in every frame. Other fields may exist only in a specific frame type.

FIG. 7 is a diagram illustrating a Frame Control field in a MAC frame in a wireless communication system to which the present invention can be applied.

Referring to FIG. 7, the Frame Control field includes a Protocol Version subfield, a Type subfield, a Subtype subfield, a To DS subfield, a From DS subfield, and more fragments. A subfield, a retry subfield, a power management subfield, a more data subfield, a protected frame subfield, and an order subfield.

The Protocol Version subfield may indicate the version of the WLAN protocol applied to the corresponding MAC frame.

The Type subfield and the Subtype subfield may be set to indicate information for identifying a function of a corresponding MAC frame.

The type of the MAC frame may include three frame types: a management frame, a control frame, and a data frame.

Each frame type may be further divided into subtypes.

For example, control frames include request to send (RTS) frames, clear-to-send (CTS) frames, acknowledgment (ACK) frames, PS-Poll frames, content free (End) frames, CF End + CF-ACK frame, Block Acknowledgment request (BAR) frame, Block Acknowledgment (BA) frame, Control Wrapper (Control + HTcontrol) frame, VHT null data packet notification (NDPA) It may include a Null Data Packet Announcement and a Beamforming Report Poll frame.

Management frames include beacon frames, announcement traffic indication message (ATIM) frames, disassociation frames, association request / response frames, reassociation requests / responses Response frame, Probe Request / Response frame, Authentication frame, Deauthentication frame, Action frame, Action No ACK frame, Timing Advertisement It may include a frame.

The To DS subfield and the From DS subfield may include information necessary to interpret the Address 1 field or the Address 4 field included in the corresponding MAC frame header. In the case of a control frame, both the To DS subfield and the From DS subfield are set to '0'. For a Management frame, the To DS subfield and the From DS subfield are set to '1' and '0' in order if the frame is a QoS Management frame (QMF), and in order if the frame is not QMF. Both can be set to '0', '0'.

The More Fragments subfield may indicate whether there is a fragment to be transmitted following the corresponding MAC frame. If there is another fragment of the current MSDU or MMPDU, it may be set to '1', otherwise it may be set to '0'.

The Retry subfield may indicate whether the corresponding MAC frame is due to retransmission of a previous MAC frame. In case of retransmission of the previous MAC frame, it may be set to '1', otherwise it may be set to '0'.

The power management subfield may indicate a power management mode of the STA. If the value of the Power Management subfield is '1', it may indicate that the STA switches to the power save mode.

The More Data subfield may indicate whether there is an additional MAC frame to be transmitted. In addition, if there is a MAC frame to be transmitted, it may be set to '1', otherwise it may be set to '0'.

The Protected Frame subfield may indicate whether the frame body field is encrypted. If the Frame Body field includes information processed by an encrypted encapsulation algorithm, it may be set to '1', otherwise it may be set to '0'.

Information included in each field described above may follow the definition of the IEEE 802.11 system. In addition, each field described above corresponds to an example of fields that may be included in the MAC frame, but is not limited thereto. That is, each field described above may be replaced with another field or additional fields may be further included, and all fields may not be necessarily included.

FIG. 8 illustrates the HT format of the HT Control field in the MAC frame according to FIG. 6.

Referring to FIG. 8, the HT Control field includes a VHT subfield, an HT Control Middle subfield, an AC Constraint subfield, and a Reverse Direction Grant (RDG) / More PPDU (More PPDU). It may consist of subfields.

The VHT subfield indicates whether the HT Control field has the format of the HT Control field for the VHT (VHT = 1) or has the format of the HT Control field for the HT (VHT = 0). In FIG. 8, it is assumed that the HT Control field (that is, VHT = 0) for HT.

The HT Control Middle subfield may be implemented to have a different format according to the indication of the VHT subfield. A more detailed description of the HT Control Middle subfield will be given later.

The AC Constraint subfield indicates whether a mapped AC (Access Category) of a reverse direction (RD) data frame is limited to a single AC.

The RDG / More PPDU subfield may be interpreted differently depending on whether the corresponding field is transmitted by the RD initiator or the RD responder.

When transmitted by the RD Initiator, the RDG / More PPDU field is set to '1' if the RDG exists, and set to '0' if the RDG does not exist. When transmitted by the RD responder, it is set to '1' if the PPDU including the corresponding subfield is the last frame transmitted by the RD responder, and set to '0' when another PPDU is transmitted.

The HT Control Middle subfield of the HT Control field for the HT includes a link adaptation subfield, a calibration position subfield, a calibration sequence subfield, a reserved subfield, and channel state information. And / or (CSI / Steering: Channel State Information / Steering) subfield, HT NDP Announcement (HT NDP Announcement) subfield, and Reserved subfield.

The Link Adaptation subfield is a training request (TRQ) subfield, an MCS request or antenna selection indication (MAI: MCS (Modulation and Coding Scheme) Request or ASEL (Antenna Selection) Indication) subfield, and an MCS feedback sequence indication (MFSI). MCS Feedback and Antenna Selection Command / data (MFB / ASELC) subfields.

The TRQ subfield is set to 1 when the responder requests sounding PPDU transmission and is set to 0 when the responder does not request sounding PPDU transmission.

If the MAI subfield is set to 14, this indicates an ASEL indication, and the MFB / ASELC subfield is interpreted as an antenna selection command / data. Otherwise, the MAI subfield indicates an MCS request and the MFB / ASELC subfield is interpreted as MCS feedback.

When the MAI subfield indicates an MCS Request (MRQ: MCS Request), it is interpreted that the MAI subfield is composed of an MRQ (MCS request) and an MSI (MRQ sequence identifier). The MRQ subfield is set to '1' if MCS feedback is requested and set to '0' if MCS feedback is not requested. When the MRQ subfield is '1', the MSI subfield includes a sequence number for specifying an MCS feedback request. When the MRQ subfield is '0', the MSI subfield is set to a reserved bit.

Each of the above-described subfields corresponds to an example of subfields that may be included in the HT control field, and may be replaced with another subfield or may further include additional subfields.

9 illustrates the VHT format of the HT Control field in a wireless communication system to which the present invention can be applied.

Referring to FIG. 9, the HT Control field includes a VHT subfield, a HT Control Middle subfield, an AC Constraint subfield, and a Reverse Direction Grant (RDG) / More PPDU (More PPDU). It may consist of subfields.

In FIG. 9, it is assumed that the HT Control field (ie, VHT = 1) for the VHT. The HT Control field for the VHT may be referred to as a VHT Control field.

Since the description of the AC Constraint subfield and the RDG / More PPDU subfield is the same as the description of FIG. 8, the description thereof is omitted.

As described above, the HT Control Middle subfield may be implemented to have a different format according to the indication of the VHT subfield.

The HT Control Middle subfield of the HT Control field for VHT includes a reserved bit, a Modulation and Coding Scheme feedback request (MRQ) subfield, and an MRQ Sequence Identifier (MSI). Space-time block coding (STBC) subfield, MCS feedback sequence identifier (MFSI) / Least Significant Bit (LSB) of Group ID (LSB) subfield, MCS Feedback (MFB) Subfield, Group ID Most Significant Bit (MSB) of Group ID (MSB) Subfield, Coding Type Subfield, Feedback Transmission Type (FB Tx Type: Feedback transmission type) subfield and a voluntary MFB (Unsolicited MFB) subfield.

In addition, the MFB subfield may include a VHT number of space time streams (NUM_STS) subfield, a VHT-MCS subfield, a bandwidth (BW) subfield, and a signal to noise ratio (SNR). It may include subfields.

The NUM_STS subfield indicates the number of recommended spatial streams. The VHT-MCS subfield indicates a recommended MCS. The BW subfield indicates bandwidth information related to the recommended MCS. The SNR subfield indicates the average SNR value on the data subcarrier and spatial stream.

Information included in each field described above may follow the definition of the IEEE 802.11 system. In addition, each field described above corresponds to an example of fields that may be included in the MAC frame, but is not limited thereto. That is, each field described above may be replaced with another field or additional fields may be further included, and all fields may not be necessarily included.

link set up  Procedure (Link Setup Procedure)

FIG. 10 is a diagram illustrating a general link setup procedure in a wireless communication system to which the present invention can be applied.

In order for an STA to set up a link and transmit / receive data with respect to a network, a STA must first undergo a scanning procedure, an authentication procedure, an association procedure, and the like for discovering the network. The link setup procedure may also be referred to as session initiation procedure and session setup procedure. In addition, the linking procedure may be collectively referred to as the scanning, authentication, and association procedure of the link setup procedure.

In the WLAN, a scanning procedure includes a passive scanning procedure and an active scanning procedure.

FIG. 10 (a) illustrates a link setup procedure according to passive scanning, and FIG. 10 (b) illustrates a link setup procedure according to active scanning.

As shown in FIG. 10A, a passive scanning procedure is performed through a beacon frame broadcasted periodically by the AP. A beacon frame is one of management frames in IEEE 802.11, which informs the existence of a wireless network and periodically (eg, allows a non-AP STA that performs scanning to find a wireless network and participate in the wireless network). , 100msec intervals). The beacon frame contains information about the current network (for example, information about the BSS).

In order to obtain information about the network, the non-AP STA passively moves channels and waits for reception of a beacon frame. The non-AP STA that receives the beacon frame may store information about a network included in the received beacon frame, move to the next channel, and perform scanning on the next channel in the same manner. The non-AP STA receives the beacon frame to obtain information about the network, thereby completing the scanning procedure on the corresponding channel.

As described above, the passive scanning procedure has the advantage that the overall overhead is small since the procedure is completed only when the non-AP STA receives the beacon frame without having to transmit another frame. However, there is a disadvantage in that the scanning execution time of the non-AP STA increases in proportion to the transmission period of the beacon frame.

On the other hand, in the active scanning procedure as shown in FIG. 10 (b), the non-AP STA broadcasts a probe request frame while actively moving channels to discover which AP exists in the periphery, thereby receiving all of them. Request network information from the AP.

In response to receiving the probe request frame, the responder waits for a random time in order to prevent frame collision, and transmits network information in a probe response frame to the corresponding non-AP STA. Upon receiving the probe response frame, the STA may store network related information included in the received probe response frame and move to the next channel to perform scanning in the same manner. The scanning procedure is completed by the non-AP STA receiving the probe response frame to obtain network information.

The active scanning procedure has an advantage that scanning can be completed in a relatively quick time compared to the passive scanning procedure. However, since an additional frame sequence is required, the overall network overhead is increased.

After completing the scanning procedure, the non-AP STA selects a network according to its own criteria and performs an authentication procedure with the corresponding AP.

The authentication procedure is a process in which a non-AP STA transmits an authentication request frame to the AP, and in response, the AP transmits an authentication response frame to the non-AP STA, that is, 2-way. This is done by handshaking.

An authentication frame used for authentication request / response corresponds to a management frame.

The authentication frame includes an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a Robust Security Network, and a finite cyclic group. Group) and the like. This corresponds to some examples of information that may be included in the authentication request / response frame, and may be replaced with other information or further include additional information.

The non-AP STA may transmit an authentication request frame to the AP. The AP may determine whether to allow authentication for the non-AP STA based on the information included in the received authentication request frame. The AP may provide a result of the authentication process to the non-AP STA through an authentication response frame.

Through the authentication procedure, the non-AP STA and the AP authenticate each other and then establish an association.

The association process is a process in which a non-AP STA transmits an association request frame to an AP, and in response, the AP transmits an association response frame to a non-AP STA, that is, 2-way. This is done by handshaking.

The association request frame includes information related to various capabilities of the non-AP STA, beacon listening interval, service set identifier (SSID), supported rates, supported channels, RSN, and mobility. It may include information on domain, supported operating classes, TIM Broadcast Indication Map Broadcast request, interworking service capability, and the like.

Based on this, the AP determines whether support for the corresponding non-AP STA is possible. After the determination, the AP transmits information on whether to accept the association request, the reason for the association request, and capability information that can be supported in the association response frame to the non-AP STA.

Association response frames include information related to various capabilities, status codes, association IDs (AIDs), support rates, Enhanced Distributed Channel Access (EDCA) parameter sets, Received Channel Power Indicators (RCPI), Received Signal to Noise Indicators (RSNI), mobility Information such as a domain, a timeout interval (association comeback time), an overlapping BSS scan parameter, a TIM broadcast response, and a Quality of Service (QoS) map may be included.

The information that may be included in the aforementioned association request / response frame corresponds to an example, may be replaced with other information, or may further include additional information.

If the non-AP STA successfully establishes an association with the AP, normal transmission / reception is performed. On the other hand, if the association is not successfully established with the AP, based on the reason, the non-AP STA may attempt to reassociate or attempt to associate with another AP.

Media access mechanism

In IEEE 802.11, communication is fundamentally different from the wired channel environment because the communication takes place over a shared wireless medium.

In a wired channel environment, communication is possible based on carrier sense multiple access / collision detection (CSMA / CD). For example, once a signal is transmitted from the transmitter, the channel environment does not change so much that the receiver does not experience significant signal attenuation. At this time, if two or more signals collided, detection was possible. This is because the power sensed by the receiver is instantaneously greater than the power transmitted by the transmitter. However, in a wireless channel environment, a variety of factors (e.g., large attenuation of the signal depending on distance, or instantaneous deep fading) can affect the channel so that the signal actually transmits properly at the receiving end. Whether this has occurred or a collision has occurred, the transmitter cannot accurately perform carrier sensing.

Accordingly, in a WLAN system according to IEEE 802.11, a carrier sense multiple access with collision avoidance (CSMA / CA) mechanism is introduced as a basic access mechanism of a MAC. The CAMA / CA mechanism is also called the Distributed Coordination Function (DCF) of the IEEE 802.11 MAC. It basically employs a “listen before talk” access mechanism. According to this type of access mechanism, the AP and / or STA may sense a radio channel or medium during a predetermined time interval (eg, DCF Inter-Frame Space (DIFS)) prior to starting transmission. Perform Clear Channel Assessment (CCA) sensing. As a result of sensing, if it is determined that the medium is in an idle state, the frame transmission is started through the medium. On the other hand, if the medium is detected to be occupied status, the AP and / or STA does not start its own transmission and assumes that several STAs are already waiting to use the medium. The frame transmission may be attempted after waiting longer for a delay time (eg, a random backoff period) for access.

By applying a random backoff period, assuming that there are several STAs for transmitting a frame, the STAs are expected to have different backoff period values, so that they will wait for different times before attempting frame transmission. This can minimize collisions.

In addition, the IEEE 802.11 MAC protocol provides a hybrid coordination function (HCF). HCF is based on the DCF and Point Coordination Function (PCF). The PCF refers to a polling-based synchronous access scheme in which polling is performed periodically so that all receiving APs and / or STAs can receive data frames. In addition, the HCF has an Enhanced Distributed Channel Access (EDCA) and an HCF Controlled Channel Access (HCCA). EDCA is a competition-based approach for providers to provide data frames to a large number of users, and HCCA is a non-competition-based channel access scheme using a polling mechanism. In addition, the HCF includes a media access mechanism for improving the quality of service (QoS) of the WLAN, and can transmit QoS data in both a contention period (CP) and a contention free period (CFP).

11 is a diagram for explaining an arbitrary backoff period and a frame transmission procedure in a wireless communication system to which the present invention can be applied.

When a certain medium changes from occupy or busy to idle, several STAs may attempt to transmit data (or frames). At this time, as a method for minimizing the collision, STAs may select a random backoff count and wait for a slot time corresponding thereto to attempt transmission. The random backoff count has a pseudo-random integer value and may be determined as one of values uniformly distributed in the range of 0 to a contention window (CW). Where CW is a contention window parameter value. The CW parameter is given CWmin as an initial value, but may take a double value when transmission fails (eg, when an ACK for a transmitted frame is not received). When the CW parameter value is CWmax, data transmission can be attempted while maintaining the CWmax value until the data transmission is successful. If the data transmission is successful, the CW parameter value is reset to the CWmin value. The CW, CWmin and CWmax values are preferably set to 2n-1 (n = 0, 1, 2, ...).

When the random backoff process begins, the STA counts down the backoff slot according to the determined backoff count value and continuously monitors the medium during the countdown. If the medium is monitored as occupied, it stops counting down and waits, and resumes counting down when the medium is idle.

In the example of FIG. 11, when a packet to be transmitted to the MAC of the STA 3 arrives, the STA 3 may confirm that the medium is idle as much as DIFS and transmit the frame immediately.

Meanwhile, the remaining STAs monitor and wait for the medium to be busy. In the meantime, data may be transmitted in each of STA 1, STA 2, and STA 5, and each STA waits for DIFS when the medium is monitored in an idle state, and then backoff slots according to a random backoff count value selected by each STA. Counts down.

In the example of FIG. 11, STA 2 selects the smallest backoff count value and STA 1 selects the largest backoff count value. That is, at the time when STA 2 finishes the backoff count and starts frame transmission, the remaining backoff time of STA 5 is shorter than the remaining backoff time of STA 1.

STA 1 and STA 5 stop counting and wait while STA 2 occupies the medium. When the media occupancy of the STA 2 ends and the medium becomes idle again, the STA 1 and the STA 5 resume the stopped backoff count after waiting for DIFS. That is, the frame transmission can be started after counting down the remaining backoff slots by the remaining backoff time. Since the remaining backoff time of STA 5 is shorter than that of STA 1, frame transmission of STA 5 is started.

Meanwhile, while STA 2 occupies the medium, data to be transmitted may also occur in STA 4. At this time, when the medium is in the idle state, the STA 4 waits for DIFS and then counts down the backoff slot according to the random backoff count value selected by the STA.

In the example of FIG. 11, the remaining backoff time of STA 5 coincides with an arbitrary backoff count value of STA 4, and in this case, a collision may occur between STA 4 and STA 5. If a collision occurs, neither STA 4 nor STA 5 receive an ACK, and thus data transmission fails. In this case, STA4 and STA5 select a random backoff count value after doubling the CW value and perform countdown of the backoff slot.

Meanwhile, the STA 1 may wait while the medium is occupied due to the transmission of the STA 4 and the STA 5, wait for DIFS when the medium is idle, and then start frame transmission after the remaining backoff time passes.

The CSMA / CA mechanism also includes 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.

In addition, a robust collision detect mechanism has been introduced to reduce the possibility of collision. This will be described with reference to FIGS. 12 and 13. Although the actual carrier sensing range and transmission range may not be the same, it is assumed to be the same for convenience of description.

12 is a diagram for describing a hidden node and an exposed node in a wireless communication system to which the present invention can be applied.

12A illustrates an example of a hidden node, in which STA A and STA B are in communication and STA C has information to transmit. In more detail, although STA A is transmitting information to STA B, it may be determined that the medium is idle when STA C performs carrier sensing before sending data to STA B. This is because transmission of STA A (ie, media occupation) may not be sensed at the location of STA C. In this case, since STA B receives the information of STA A and STA C at the same time, a collision occurs. At this time, STA A may be referred to as a hidden node of STA C.

FIG. 12 (b) is an example of an exposed node, where STA B has information to be transmitted from STA D in a situation in which data is transmitted to STA A. FIG. In this case, when STA C performs carrier sensing, it may be determined that the medium is occupied by the transmission of STA B. Accordingly, since STA C is sensed as a medium occupancy state even if there is information to be transmitted to STA D, it must wait until the medium becomes idle. However, since STA A is actually outside the transmission range of STA C, transmission from STA C and transmission from STA B may not collide with STA A's point of view, so STA C is unnecessary until STA B stops transmitting. To wait. At this time, STA C may be referred to as an exposed node of STA B.

13 is a view for explaining the RTS and CTS in a wireless communication system to which the present invention can be applied.

In order to efficiently use a collision avoidance mechanism in the exemplary situation as shown in FIG. 12, short signaling packets such as request to send (RTS) and clear to send (CTS) may be used. . The RTS / CTS between the two STAs may allow the surrounding STA (s) to overhear, allowing the surrounding STA (s) to consider whether to transmit information between the two STAs.

The RTS frame and the CTS frame include information indicating a time interval in which a wireless medium required for transmission and reception of an ACK frame is reserved when substantial data frame transmission and acknowledgment (ACK) are supported. The other STA that receives the RTS frame transmitted from the AP and / or the STA to which the frame is to be transmitted or receives the CTS frame transmitted from the STA to which the frame is to be transmitted during the time period indicated by the information included in the RTS / CTS frame Can be set to not access the medium. This may be implemented by setting the NAV during the time interval.

FIG. 13A illustrates an example of a method for solving a hidden node problem, and assumes that STA A and STA C both attempt to transmit data to STA B. FIG. When STA A sends the RTS to STA B, STA B transmits the CTS to both STA A and STA C around it. As a result, STA C waits until data transmission between STA A and STA B is completed, thereby avoiding collision.

FIG. 13B illustrates an example of a method for solving an exposed node problem, and STA C overhears RTS / CTS transmission between STA A and STA B, so that STA C is a different STA (eg, STA). It may be determined that no collision will occur even if data is transmitted to D). That is, STA B transmits the RTS to all the surrounding terminals, and only STA A having the data to actually transmit the CTS. Since STA C receives only RTS and not STA A's CTS, it can be seen that STA A is out of STC C's carrier sensing.

HE system

Hereinafter, a next generation WLAN system will be described. The next generation WLAN system is a next generation WIFI system, and may be described as an example of IEEE 802.11ax as an embodiment of the next generation WIFI system. In the present specification, the following next-generation WLAN systems may be referred to as HE (High Efficiency) systems, and frames, PPDUs, and the like of the system may be referred to as HE frames, HE PPDUs, HE-SIG fields, HE-STFs, and HE-LTFs. have.

The description of the existing WLAN system such as the above-described VHT system may be applied to the HE system, which is not further described below. For example, for the VHT-SIG A field, VHT-STF, VHT-LTF and HE-SIG-B fields described above for the HE-SIG A field, HE-STF, HE-LTF and HE-SIG-B fields. Description may apply. The HE frame and the preamble of the proposed HE system may be used only for other wireless communication or cellular systems. The HE STA may be a non-AP STA or an AP STA as described above. Although referred to as STA in the following specification, such a STA device may represent an HE STA device.

In the HE system, the HE format PPDU may be largely composed of a legacy part (L-part), an HE part (HE-part), and an HE data (HE-data) field.

The L-part is composed of an L-STF field, an L-LTF field, and an L-SIG field in the same manner as the conventional WLAN system maintains. The L-STF field, L-LTF field, and L-SIG field may be referred to as a legacy preamble.

The HE-part is a part newly defined for the 802.11ax standard and may include an HE-STF field, an HE-SIG field, and an HE-LTF field. The HE-STF field, the HE-SIG field, and the HE-LTF field may be configured in various orders. For example, the HE-part may be configured in the order of the HE SIG field → HE STF field → HE LTF field. However, the present invention is not limited thereto, and each field may be configured in various orders, and at least one field may be omitted. In addition to the HE-STF field and the HE-LTF field, the HE-SIG field may be collectively referred to as an HE-preamble. The HE-SIG field may include a HE-SIG A field and a HE-SIG B field.

The HE-SIG A field may include common control information transmitted in common to STAs receiving a PPDU. The HE-SIG A field may be transmitted in at least one OFDM symbol. The HE-SIG A field may be copied in units of 20 MHz and include the same information. In addition, the HE-SIG-A field informs the total bandwidth information of the system. In an embodiment, the HE-SIG A field may include bandwidth information, group ID information, stream information, UL indication information, guard interval indication information, allocation information, and transmission power. It may include at least one of the information.

The HE-SIG B field may include user-specific information required for each STA to receive its own data (eg, PPDU). For example, the HE-SIG B field may include information about a modulation and coding scheme (MCS) of the corresponding PPDU and a length of the corresponding PPDU. The HE-SIG B field may be transmitted in at least one OFDM symbol.

For convenience of description, the legacy preamble (or L-part) and the HE preamble (or HE-part) may be collectively referred to as a "physical preamble" of the PPDU. In addition, hereinafter, the HE data field may be referred to as a “data field”.

The HE system intends to use an FFT size four times larger than the conventional WLAN system for average throughput enhancement and outdoor robust transmission of the outdoor. When the 4x FFT scheme is applied, the symbol period of the symbol to which the 4x FFT scheme is applied is quadrupled. This is an example of using a 4x FFT size, in which the entire bandwidth is constant and the subcarrier spacing is used 1/4 times. Since the spacing between subcarriers is 1/4, The period can be four times.

In addition, the 1x FFT size, which is the basis of the 4x FFT size, may be the FFT size of the VHT system (IEEE 802.11ac). Accordingly, the 1x FFT size, which is a reference of the 4x FFT size, may correspond to the FFT size of the legacy preamble portions L-STF, L-LTF, and L-SIG of the frame. The period of one preamble for 1x FFT can be expressed by adding IDFT / DFT period 3.2us and guard interval symbol period, 4us (3.2 + 0.8) for long guard interval period (Long GI symbol interval), short guard interval In the case of a short GI symbol interval, it may be 3.6us (3.2 + 0,4). Since the symbol period of the data portion is 3.2us, if the 4x FFT scheme is applied in the HE system, one symbol period may be 12.8us. Alternatively, the symbol period of the data portion may be represented as 12.8us at 4 times the IDFT / DFT period.

In the HE system, an OFDMA scheme may be used to transmit and receive more data to a plurality of STAs at the same time. Orthogonal Frequency Division Multiple Access (OFDMA) is a multi-user version of an OFDM digital modulation scheme. The OFDMA scheme represents a scheme in which a plurality of users are allocated a subset of subcarriers as resource units instead of monopolizing a multicarrier, that is, a subcarrier according to the OFDM scheme. A subcarrier (or subcarrier) used in OFDMA may be referred to as a tone, and a tone plan for how to allocate these tones to each STA and how to arrange left tones allocated to each STA Suggested below.

Meanwhile, a channel to be described below means a transmission channel (or bandwidth of a PPDU) of a PPDU. That is, the 20 MHz channel means that the bandwidth of the transmitted PPDU is 20 MHz, the 40 MHz channel means that the bandwidth of the transmitted PPDU is 40 MHz, and the 80 MHz channel may mean that the bandwidth of the transmitted PPDU is 80 MHz.

1.Tone Plan on 20 MHz Channel

In an 802.11ax (or HE) system, a 4x FFT (4x is based on an existing 802.11ac system), a 20 MHz channel in the frequency domain can contain a total of 256 (64 * 4) tones. Alternatively, since a 4x FFT (4x is based on an existing 802.11ac system) in an 802.11ax (or HE) system, a total of 256 (64 * 4) tones may be located in a 20 MHz channel in the frequency domain. In this case, the tones of the 20 MHz channel may be set in a resource unit in n tone units (n-tone). Here, n means a natural number larger than zero. For example, the tones of the 20 MHz channel may be configured with a resource unit in units of 26-tones, 52-tones, 106-tones, or 242-tones. In this case, six tones of 256 tones of the 20 MHz channel may be set as left guard tones, three tones as DC tones, and five tones as right guard tones. . In the frequency domain, the left guard tones and the light guard tones may be located across the 20 MHz channel, and the DC tones may be located in the center frequency region of the 20 MHz channel. Thus, the number of tones that can be allocated substantially as a resource unit is 242-tons (= 256-6-5-3).

When using a 26-tone resource unit (hereinafter, '26 -tone resource unit ') as a unit for allocating a frequency resource of a 20 MHz channel, a 242-tone is 9 * 26-tone + 8. That is, a 242-tone of a 20 MHz channel can be divided into nine 26-tone resource units and eight left over tones.

When using a 26-tone resource unit and a 52-tone resource unit (hereinafter, referred to as a '52 -tone resource unit ') as a unit for allocating a frequency resource of a 20 MHz channel, a 24-2-tone is 1 * 26-tone + 4 * 52-tons +8. That is, a 242-tone of a 20 MHz channel can be divided into one 26-tone resource unit, four 52-tone resource units, and eight left over tones.

When using a 26-tone resource unit and a 106-tone resource unit (hereinafter, referred to as a 106-tone resource unit) as a unit for allocating a frequency resource of a 20 MHz channel, 242-tones are 1 * 26 + 2 * 106 + 4. That is, a 242-tone of a 20 MHz channel can be divided into one 26-tone resource unit, two 106-tone resource units, and four left over tones.

When using a 24-2-tone resource unit (hereinafter, '242-tone resource unit') as a unit for allocating a frequency resource of a 20 MHz channel, the 24-2-tone is 1 * 242. That is, the 242-tone of the 20MHz channel may be divided into one 242-tone resource unit, and the left over tone may not exist.

In addition to the above-described embodiments, the frequency resources of the 20 MHz channel may be divided into various combinations of 26-tone resource units, 52-tone resource units, 106-tone resource units, and 242-tone resource units, and left over tones.

In particular, resource units in small tones divided as frequency resources in a 20 MHz channel may be grouped and re-divided into resource units in larger tones. For example, two 26-tone resource units are grouped into one 52-tone (26 + 26) resource unit, two 52-tone resource units and two left over tones are grouped into one 106-tone ( 2 * 52 + 2) resource unit, two 106-tone resource units, one 26-tone resource unit and four left over tones grouped together to form one 242-tone (2 * 106 + 26 + 4) resource It can be divided into units. In this case, however, the centrally located 26-tone resource unit may not be used to construct a 52-tone resource unit and a 106-tone resource unit.

Therefore, even when the frequency resource is divided into 26-tone resource units as described above, the frequency resource is grouped into resource units of larger tones by grouping the 26-tone resource units and the left over tones into larger unit units. And left overtone.

In a similar manner, each of the resource units in large tones may be separated into resource units in small tones.

One or more resource units classified in the 20 MHz channel may be allocated to at least one STA as frequency resources.

Hereinafter, a tone plan regarding the position of left over tones generated by dividing a frequency resource (242-tone) of a 20 MHz channel into resource unit units of the above-described tone size will be proposed.

<First Embodiment>

14 illustrates a tone plan of a 20 MHz channel according to the first embodiment of the present invention. In the drawings, the left guard tone, the light guard tone, and the DC tone are not shown for convenience of description.

Referring to FIG. 14A, a frequency resource of a 20 MHz channel may be divided into nine resource units and eight left over tones.

All nine resource units may be 26-tone resource units. In this case, the fifth resource unit may be divided into two 13-tone sub-resource units by DC tones located in the center frequency region.

Four left over tones of the eight left over tones may be located in the center frequency region. More specifically, the four left over tones may be located with DC tones in the center frequency region between two separate 13-tone sub-resource units. The four left over tones and the three DC tones located in the center frequency region can be divided into 'DC tones'. In this case, a total of seven (3 + 4) DC tones are located in the center frequency region of the 20 MHz channel. This increase in the number of DC tones has the effect of having a robust performance in the carrier frequency offset (CFO) measurement.

The remaining four left over tones (first to fourth left over tones) except for the four left over tones divided into DC tones among the eight left over tones may be located between resource units in the frequency domain.

For example, as shown in this figure,

The first and second left over tones are between the second and third resource units, and

The third and fourth left over tones may be located between the seventh and eighth resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to FIG. 14B, a frequency resource of a 20 MHz channel may be divided into five resource units and eight left over tones.

The first, second, fourth, and fifth resource units of the five resource units may be 52-tone resource units, and the third resource unit may be a 26-tone resource unit. The third resource unit may be separated into two 13-tone sub resource units by a DC tone located in the center frequency region. In this case, four left over tones of the eight left over tones are located in the center frequency region and may be divided into the DC tones as described above.

The remaining four left over tones (first to fourth left over tones) of the eight left over tones may be located between resource units in the frequency domain.

E.g,

The first and second left over tones are between the first and second resource units, and

The third and fourth left over tones may be located between the fourth and fifth resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to FIG. 14C, a frequency resource of a 20 MHz channel may be divided into three resource units and four left over tones.

The first of the three resource units, and the third resource unit may be a 106-tone resource unit, and the second resource unit may be a 26-ton resource unit. The second resource unit may be separated into two 13-tone sub resource units by a DC tone located in the center frequency region. In this case, four left over tones of the eight left over tones are located in the center frequency region and may be divided into the DC tones as described above. In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to FIG. 14 (d), frequency resources of a 20 MHz channel may be divided into one resource unit.

In this case, the one resource unit may be a 242-tone resource unit. If all of the 242-tones, which are frequency resources of the 20MHz channel, are divided into one resource unit, the left over tone may not exist. Accordingly, unlike the case of FIGS. 14A to 14C, since there is no left over tone that may be divided into DC tones, only three DC tones (not shown) may be located in the center frequency region of the 20 MHz channel. have.

Furthermore, the tone plans of FIGS. 14A to 14D may be combined or modified in various forms to form new tone plans.

As one example, resource units in smaller tones may be grouped into resource units in larger tones to form a new tone plan. More specifically, two 26-tone resource units are one 52-tone resource unit, two 52-tone resource units and two left over tones are one 106-tone resource unit, two 106-tone resource units. Tone resource units, one 26-tone resource unit, and four left over tones may be grouped into one 242-tone resource unit. When applying this grouping scheme, various tone plans may be derived from the tone plans of FIGS. 14 (a) to 14 (d).

For example, when the above-described grouping scheme is applied to FIG. 14 (a), a 52-tone resource unit (grouping two 26-tone resource units) + two left over tones + three 26-tone resource units A new tone plan can be derived that consists of + 106-tone resource units (grouping four 26-tone resource units and two left over tones).

Similarly, each of the resource units in large tones may be separated into resource units in small tones to form a new tone plan.

As another example, in the tone plans of FIGS. 14 (a) to 14 (d), the tone plan on the left (hereinafter referred to as the 'left tone plan') and the tone plan on the right (hereinafter referred to as the 'right tone plan') are centered on DC tones. May be combined to form a new tone plan. For example, a new tone plan may be formed by combining the left tone plan of FIG. 14 (a) and the right tone plan of FIG. 14 (b). In this case, the newly formed tone plan consists of two 26-tone resource units + two left over tones + three 26-tone resource units + one 52-tone resource unit + two left over tones + one 52- It may be configured in tone resource unit order.

That is, the tone plans of FIGS. 14 (a) to 14 (d) may be combined with each other, grouping resource units into resource units in larger tones or separating new tone plans into resource units in smaller tones. Can be derived.

In the tone plan proposed in the first embodiment, at least one left over tone located between 52-tone resource units has an effect of reducing interference between 52-tone resource units. In addition, according to the tone plan of the first embodiment, there is an advantageous effect in terms of peak-to-average power ratio (PAPR) of the STF sequence. In addition, even when the tone plan of the first embodiment is extended to 40 MHz (2 * 20 MHz) and 80 MHz (4 * 20 MHz) channels, left over tone arrangement between 52-tone resource units can be ensured. This will be described later in detail with reference to FIGS. 17 and 22.

In addition, when using a 2x FFT size HE-LTF, the pilot tone for CFO estimation should be an even tone, and even left (for example, 2 or 4) paired left over tones are resource units as in the first embodiment. In the case where it is located between them, it is possible to ensure that the pilot tone is even ton, assuming that the pilot tones are located in the same place within each resource unit of the same size. In the present specification, the even tone means a tone located at an index having an even value among all the tones included in the transmission channel band.

15 illustrates an index of a leftover tone according to an embodiment of the present invention.

Referring to FIG. 15A, when the leftover tone is odd between resource units, some of the pilot tones may have an odd index (in the case of FIG. 15A, -63 and -49). However, when left over tones are paired in even numbers and located between resource units, as shown in FIG. 15 (b), the pilot tones may be all tones. Therefore, when following the tone plan proposed in the first embodiment (i.e., when pilot tones are paired and placed in even (e.g., 2 or 4) units), it is possible to ensure that the pilot tones become even tones. have.

Furthermore, according to the first embodiment, there is an advantage in that pilot tone positions of resource units having the same number of tones are identically located on the left or right side with respect to DC tones. In this case, the pilot tone positions of resource units that are located symmetrically to the left and right with respect to the positions of the DC tones also have the same tone number, also have symmetrical symmetry with respect to the DC tones.

Second Embodiment

16 illustrates a tone plan of a 20 MHz channel according to a second embodiment of the present invention. Figures 16 (a) and 16 (b) correspond to the tone plans of Figures 14 (a) and 14 (b), respectively, and the tones of Figures 14 (a) and 14 (b) except for the position of some left over tones. It is substantially the same as the plan. Therefore, hereinafter, the tone plan proposed in FIG. 16 will be described in detail with reference to the difference from FIG. 14. In the drawings, the left guard tone, the light guard tone, and the DC tone are not shown for convenience of description.

Referring to FIG. 16A, four left over tones of the eight left over tones may be divided into DC tones in the center frequency region. Among the eight left over tones, the remaining four left over tones (first to fourth left over tones) except for the four left over tones divided into DC tones may be located adjacent to the resource unit.

E.g,

The first and second left over tones are to the left of the first resource unit, and

The third and fourth left over tones may be located to the right of the ninth resource unit.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to FIG. 16 (b), four left over tones of the eight left over tones may be divided into DC tones in the center frequency region. Among the eight left over tones, the remaining four left over tones (first to fourth left over tones) except for the four left over tones divided into DC tones may be located adjacent to the resource unit. E.g,

The first and second left over tones are to the left of the first resource unit, and

The third and fourth left over tones may be located to the right of the fifth resource unit.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Further, as described above in connection with FIGS. 14A-14D, the left tone plan and the right tone plan disclosed in FIGS. 16A, 16B, 14C, and 14D are shown. Can be combined to form a new tone plan. Also, the resource units of FIGS. 16 (a), 16 (b) 14 (c), and 14 (d) may be grouped into resource units in larger tones or separated into smaller resource units in new tones. Tone plans can be formed. The tone plan proposed in the second embodiment has the effect of reducing interference from adjacent channels. Further, according to the tone plan proposed in the second embodiment, when using a 2x FFT size HE-LTF, pilot tone positions of resource units having the same number of tones positioned to correspond to the left and the right on the basis of DC tones At the same time, it is possible to ensure that the pilot tone is even tone. In this case, the pilot tone positions of resource units that are located symmetrically to the left and right with respect to the positions of the DC tones also have the same tone number, also have symmetrical symmetry with respect to the DC tones.

Third Embodiment

17 illustrates a tone plan of a 20 MHz channel according to a third embodiment of the present invention. Figures 17 (a) and 17 (b) correspond to the tone plans of Figures 14 (a) and 14 (b), respectively, and the tones of Figures 14 (a) and 14 (b) except for the position of some left over tones. It is substantially the same as the plan. Therefore, hereinafter, the tone plan proposed in FIG. 17 will be described in detail with reference to the difference from FIG. 14. In the drawings, the left guard tone, the light guard tone, and the DC tone are not shown for convenience of description.

Referring to FIG. 17A, four left over tones of the eight left over tones may be divided into DC tones in the center frequency region. Among the eight left over tones, the remaining four left over tones (first to fourth left over tones) except for the four left over tones divided into DC tones may be located between resource units. E.g,

The first and second left over tones are between the fourth and fifth resource units, and

The third and fourth left over tones may be located between the fifth and sixth resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to FIG. 17B, four left over tones of the eight left over tones may be divided into DC tones in the center frequency region. Among the eight left over tones, the remaining four left over tones (first to fourth left over tones) except for the four left over tones divided into DC tones may be located between resource units.

E.g,

The first and second left over tones are between the second and third resource units, and

The third and fourth left over tones may be located between the third and fourth resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Further, as described above with respect to FIGS. 14A-14D, the left tone plan and the right tone plan disclosed in FIGS. 17A, 17B, 14C, and 14D are Can be combined to form a new tone plan. In addition, the resource units of FIGS. 17A, 17B, 14C, and 14D may be grouped into resource units in larger tones or divided into resource units in smaller tones. New tone plans can be formed. The tone plan proposed in the third embodiment has an advantageous effect in terms of PAPR of the STF sequence. In addition, when using the HE-LTF of the 2x FFT size, according to the tone plan of the third embodiment, the pilot tone positions of the resource units having the same number of tones located to correspond to each other on the left and right sides based on the DC tones are the same. At the same time, it is possible to ensure that the pilot tone is even tone. In this case, the pilot tone positions of resource units that are located symmetrically to the left and right with respect to the positions of the DC tones also have the same tone number, also have symmetrical symmetry with respect to the DC tones.

As described above, in a 20 MHz channel, four left over tones of eight left over tones may be divided into DC tones, and the remaining four left over tones may be between resource units or resource units according to an embodiment. It can be located next to. The first to third embodiments described above may be applied selectively or in combination according to the purpose and effect.

2. 40MHz Channel Tone Plan

In an 802.11ax (or HE) system, a 4x FFT (4x is based on an existing 802.11ac system), the 40MHz channel in the frequency domain can include a total of 512 (4 * 128) tones. Alternatively, since a 4x FFT (4x is based on an existing 802.11ac system) in an 802.11ax (or HE) system, a total of 512 tones may be located in a 40 MHz channel in the frequency domain. At this time, the tones of the 40MHz channel may be set to the resource unit in units of n tones. Here, n means a natural number larger than zero. For example, the tones of the 40 MHz channel may be set in resource units in units of 26-tones, 52-tones, 106-tones, 242-tones, and 484-tones.

Twelve tones of the 512 tones of the 40 MHz channel may be set as left guard tones, five tones as DC tones, and 11 tones as right guard tones. In the frequency domain, the left guard tones and the light guard tones may be located across the 40 MHz channel, and the DC tones may be located in the center frequency region of the 40 MHz channel. Thus, the number of tones that can be allocated substantially as a resource unit is 484-tons (= 512-12-5-11).

When using a 26-tone resource unit as a unit for allocating a frequency resource of a 40 MHz channel, the 484-tone becomes 18 * 26 + 16. That is, the 484-tone of the 40 MHz channel can be divided into 18 26-tone resource units and 16 left over tones.

When using a 26-tone resource unit and a 52-tone resource unit as a unit for allocating a frequency resource of a 40 MHz channel, the 484-tone becomes 2 * 26 + 8 * 52 + 16. That is, the 484-tone of the 40 MHz channel can be divided into two 26-tone resource units, eight 52-tone resource units and 16 left over tones.

When using a 26-tone resource unit and a 106-tone resource unit as a unit for allocating a frequency resource of a 40 MHz channel, the 484-tone becomes 2 * 26 + 4 * 106 + 8. That is, the 484-tone of the 40 MHz channel can be divided into two 26-tone resource units, four 106-tone resource units, and eight left over tones.

When using a 24-2-tone resource unit as a unit for allocating a frequency resource of a 40 MHz channel, the 484-tone is 2 * 242. That is, the 484-tone of the 40 MHz channel may be divided into two 242-tone resource units, and the left over tone may not exist.

When using a resource unit composed of 484-tons (hereinafter, '484-tone resource unit') as a unit for allocating a frequency resource of a 40 MHz channel, the 484-tone is 1 * 484. That is, the 484-tone of the 40 MHz channel may be divided into one 484-tone resource unit, and the left over tone may not exist.

In addition to the above-described embodiments, the frequency resources of the 40 MHz channel are in various combinations of 26-tone resource units, 52-tone resource units, 106-tone resource units, and 242-tone resource units, 484-tone resource units, and left over tones. Can be distinguished.

In particular, resource units in small tones divided as frequency resources in the 40 MHz channel may be grouped and re-divided into resource units in larger tones. For example, two 26-tone resource units are grouped into one 52-tone (26 + 26) resource unit, two 52-tone resource units and two left over tones are grouped into one 106-tone ( 2 * 52 + 2) resource unit, two 106-tone resource units, one 26-tone resource unit and four left over tones grouped together to form one 242-tone (2 * 106 + 26 + 4) resource As a unit, two 242-tone resource units can be grouped into one 484-tone (2 * 242) resource unit.

Therefore, even when the frequency resource is divided into 26-tone resource units as described above, the frequency resource is grouped into resource units of larger tones by grouping the 26-tone resource units and the left over tones into larger unit units. And left overtone.

In a similar manner, each of the resource units in large tones may be separated into resource units in small tones. One or more resource units classified in the 40 MHz channel may be allocated to at least one STA as frequency resources.

Hereinafter, a tone plan relating to the position of left over tones generated by dividing a frequency resource (484-tone) of a 40 MHz channel into resource unit units of the above-described tone size will be proposed.

Fourth Example

18 illustrates a tone plan of a 40 MHz channel according to a fourth embodiment of the present invention. FIG. 18 proposes a structure in which the tone plan of the first embodiment shown in FIG. 14 is repeated twice. In the drawings, the left guard tone, the light guard tone, and the DC tone are not shown for convenience of description.

Referring to FIG. 18A, a frequency resource of a 40 MHz channel may be divided into 18 resource units and 16 left over tones.

All 18 resource units may be 26-tone resource units. In this case, the fifth and fourteenth resource units may be separated into two 13-tone sub-resource units by left over tones located at the center.

Sixteen left over tones (first to sixteen left over tones) may be located between resource units in the frequency domain.

E.g,

The first and second left over tones are between the second and third resource units,

The third to sixth left over tones are the center of the fifth resource unit (or between the 13-tone subresource units included in the fifth resource unit),

The seventh and eighth left over tones are between the seventh and eighth resource units, and the ninth and tenth left over tones are between the eleventh and twelfth resource units;

The eleventh to fourteenth left over tones are between the center of the fourteenth resource unit (or between 13-tone subresource units included in the fourteenth resource unit), and

The 15th and 16th left over tones may be located between the 16th and 17th resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to FIG. 18B, a frequency resource of a 40 MHz channel may be divided into 10 resource units and 16 left over tones.

The first, second, fourth to seventh, ninth, and tenth resource units of the ten resource units may be 52-tone resource units. And the third and eighth resource units may be 26-tone resource units. In this case, the third and eighth resource units may be separated into two 13-tone sub resource units, respectively, by left over tones located at the center.

Sixteen left over tones (first to sixteen left over tones) may be located between resource units in the frequency domain.

E.g,

The first and second left over tones are between the first and second resource units,

The third to sixth left over tones are the center of the third resource unit (or between the 13-tone sub-resource units included in the third resource unit),

The seventh and eighth left over tones are between the fourth and fifth resource units,

The ninth and tenth left over tones are between the sixth and seventh resource units,

The eleventh to fourteenth left over tones are the center of the eighth resource unit (or between the 13-tone subresource units included in the eighth resource unit), and

The fifteenth and sixteenth left over tones may be located between the ninth and tenth resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to FIG. 18C, a frequency resource of a 40 MHz channel may be divided into six resource units and eight left over tones.

The first, third, fourth, and sixth resource units of the six resource units may be 106-tone resource units. And the second and fifth resource units may be 26 ton resource units. In this case, the second and fifth resource units may be separated into two 13-tone sub resource units, respectively, by the left over tones located in the center.

Eight left over tones (first to eighth left over tones) may be located between resource units in the frequency domain.

E.g,

The first to fourth left over tones are at the center of the second resource unit (or between 13-tone sub resource units included in the second resource unit), and

The fifth to eighth left over tones may be located at the center of the fifth resource unit (or between 13-tone subresource units included in the fifth resource unit).

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to FIG. 18D, a frequency resource of a 40 MHz channel may be divided into two resource units, and there is no left over tone. In this case, the two resource units may be 242-tone resource units.

Referring to FIG. 18E, a frequency resource of a 40 MHz channel may be divided into one resource unit, and there is no left over tone. In this case, the one resource unit may be a 484-tone resource unit.

Furthermore, the tone plans of FIGS. 18A to 18E described above may be combined or modified in various forms to form new tone plans.

As one example, resource units in smaller tones may be grouped into resource units in larger tones to form a new tone plan. More specifically, two 26-tone resource units are one 52-tone resource unit, two 52-tone resource units and two left over tones are one 106-tone resource unit, two 106-tone resource units. The tone resource units, one 26-tone resource unit and four left over tones may be grouped into one 242-tone resource unit and two 242-tone resource units into 484-tone resource units. When applying this grouping scheme, various tone plans may be derived from the tone plans of FIGS. 18 (a) to 18 (e).

For example, if the above-described grouping scheme is applied to Fig. 17 (a), one 106-tone resource unit (grouping four 26-tone resource units and two left over tones) + one 13-tone Sub-resource unit + 4 left over tones + 1 13-tone sub-resource unit + 1 52-tone resource unit (grouping 2 26-tone resource units) + 2 left over tones + 1 52-tone resource A new tone plan can be derived that consists of a unit (grouping two 26-tone resource units) + 242-tone resource unit (grouping nine 26-tone resource units and eight left over tones).

Similarly, each of the resource units in large tones may be separated into resource units in small tones to form a new tone plan.

As another example, in the tone plan of FIGS. 18 (a) to 18 (e), the tone plan on the left (hereinafter referred to as 'left tone plan') and the tone plan on the right (hereinafter referred to as 'right tone plan') are centered on DC tones. May be combined to form a new tone plan. For example, a new tone plan can be formed by combining the left tone plan of FIG. 18 (c) and the right tone plan of FIG. 18 (d). In this case, the newly formed tone plan includes one 106-tone resource unit + one 13-tone sub resource unit + four left over tones + one 13-tone sub resource unit + one 106-tone resource unit + one It may consist of 242-tone resource units.

That is, the tone plans of FIGS. 18 (a) to 18 (e) may be combined with each other, grouping resource units into resource units in larger tones, or separating new tone plans by separating them into resource units in smaller tones. Can be derived.

In the tone plan proposed in the fourth embodiment, the interference between the 52-tone resource units is reduced due to the at least one left over tone located between the 52-tone resource units. Further, according to the tone plan of the fourth embodiment, when using a 2x FFT size HE-LTF, pilot tone positions of resource units having the same number of tones positioned to correspond to each other on the left and right sides with respect to DC tones are the same. At the same time, it is possible to ensure that the pilot tone is even tone. In this case, the pilot tone positions of resource units located so as to be symmetrical to the left and right with respect to the positions of the DC tones also have symmetry with respect to the DC tones.

Fifth Embodiment

19 illustrates a tone plan of a 40 MHz channel according to a fifth embodiment of the present invention. Figures 19 (a) through 19 (e) correspond to the tone plans of Figures 18 (a) through 18 (e), respectively, and the tones of Figures 18 (a) through 18 (e) except for the position of some left over tones. It is substantially the same as the plan. Therefore, hereinafter, the tone plan proposed in FIG. 19 will be described in detail with reference to the difference from FIG. 18.

Referring to Figure 19 (a),

The first and second left over tones are between the second and third resource units,

The third and fourth left over tones are between the fourth and fifth resource units,

The fifth and sixth left over tones are between the fifth and sixth resource units,

The seventh and eighth left over tones are between the seventh and eighth resource units,

The ninth and tenth left over tones are between the eleventh and twelfth resource units;

The eleventh and twelfth left over tones are between the thirteenth and fourteenth resource units;

The 13th and 14th left over tones are between the 14th and 15th resource units,

The 15th and 16th left over tones may be located between the 16th and 17th resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to Figure 19 (b),

The first and second left over tones are between the first and second resource units,

The third and fourth left over tones are between the second and third resource units,

The fifth and sixth left over tones are between the third and fourth resource units,

The seventh and eighth left over tones are between the fourth and fifth resource units,

The ninth and tenth left over tones are between the sixth and seventh resource units,

The eleventh and twelfth left over tones are between the seventh and eighth resource units,

The 13th and 14th left over tones are between 8th and 9th resource units, and

The fifteenth and sixteenth left over tones may be located between the ninth and tenth resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to Figure 19 (c),

The first and second left over tones are between the first and second resource units,

The third and fourth left over tones are between the second and third resource units,

The fifth and sixth left over tones are between the fourth and fifth resource units,

The seventh and eighth left over tones may be located between the fifth and sixth resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Since FIG. 19 (d) is related to FIG. 18 (d) and FIG. 19 (e) is the same as described above with reference to FIG. 18 (e), overlapping descriptions are omitted.

Furthermore, as described above with reference to FIGS. 18A to 18E, a new tone plan may be formed by combining the left tone plan and the right tone plan disclosed in FIGS. 19A to 19E. . In addition, the resource units of FIGS. 19 (a) to 19 (e) may be grouped into resource units in larger tones or separated into resource units in smaller tones to form a new tone plan.

In the tone plan proposed in the fifth embodiment, due to at least one left over tone located between resource units (26-tone resource unit, 52-tone resource unit, 106-tone resource unit), The effect is that interference is reduced. Further, according to the tone plan of the fifth embodiment, when using a 2x FFT size HE-LTF, pilot tone positions of resource units having the same number of tones located to correspond to each other on the left and right sides with respect to DC tones are the same. At the same time, it is possible to ensure that the pilot tone is even tone. In this case, the pilot tone positions of resource units located so as to be symmetrical to the left and right with respect to the positions of the DC tones also have symmetry with respect to the DC tones.

Sixth Example

20 illustrates a tone plan of a 40 MHz channel according to a sixth embodiment of the present invention. 20 (a) to 20 (e) correspond to the tone plans of Figs. 18 (a) to 18 (e) respectively, and the tones of Figs. 18 (a) to 18 (e) except for the position of some left over tones. It is substantially the same as the plan. Therefore, hereinafter, the tone plan proposed in FIG. 20 will be described in detail with reference to the difference from FIG. 18.

Referring to Figure 20 (a),

The first and second left over tones are left of the first resource unit,

The third and fourth left over tones are between the second and third resource units,

The fifth and sixth left over tones are between the seventh and eighth resource units,

The seventh to tenth left over tones are between the ninth and tenth resource units,

The eleventh and twelfth left over tones are between the eleventh and twelfth resource units;

The 13th and 14th left over tones are between the 16th and 17th resource units, and

The fifteenth and sixteenth left over tones may be located to the right of the eighteenth resource unit.

The seventh to tenth left over tones may be classified as DC tones. In this case, a total of nine (4 + 5) DC tones are located in the center frequency region of the 40 MHz channel. As the number of DC tones increases, there is an effect that it has robust performance in CFO measurement. According to the tone plan of this embodiment, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to FIG. 20 (b),

The first and second left over tones are left of the first resource unit,

The third and fourth left over tones are between the first and second resource units,

The fifth and sixth left over tones are between the fourth and fifth resource units,

The seventh to tenth left over tones are between the fifth and sixth resource units,

The eleventh and twelfth left over tones are between the sixth and seventh resource units,

The 13th and 14th left over tones are between the 9th and 10th resource units, and

The fifteenth and sixteenth left over tones may be located to the right of the tenth resource unit.

The seventh to tenth left over tones may be classified as DC tones. In this case, a total of nine (4 + 5) DC tones are located in the center frequency region of the 40 MHz channel. As the number of DC tones increases, there is an effect that it has robust performance in CFO measurement. According to the tone plan of this embodiment, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to FIG. 20 (c),

The first and second left over tones are left of the first resource unit,

The third to sixth left over tones are between the third and fourth resource units, and

The seventh and eighth left over tones may be located to the right of the sixth resource unit.

The third to sixth left over tones may be classified as DC tones. In this case, a total of nine (4 + 5) DC tones are located in the center frequency region of the 40 MHz channel. As the number of DC tones increases, there is an effect that it has robust performance in CFO measurement. According to the tone plan of this embodiment, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

20 (d) is the same as described above with respect to FIG. 18 (d) and FIG. 20 (e) is the same as described above with reference to FIG.

Furthermore, as described above with reference to FIGS. 18A to 18E, a new tone plan may be formed by combining the left tone plan and the right tone plan disclosed in FIGS. 20A to 20E. . In addition, the resource units of FIGS. 20 (a) to 20 (e) may be grouped into resource units in larger tones or may be divided into resource units in smaller tones to form a new tone plan. In this case, it may be designed in consideration of the number of STAs to allocate new frequency resources and the size of frequency resources to be allocated to each STA.

In the tone plan proposed in the sixth embodiment, the adjacent channel due to at least one left over tone located at the edge of the resource units (26-tone resource unit, 52-tone resource unit, 106-tone resource unit) This has the effect of reducing interference from. Further, according to the tone plan of the sixth embodiment, when using a 2x FFT size HE-LTF, pilot tone positions of resource units having the same number of tones located to correspond to each other on the left and right sides with respect to DC tones are the same. At the same time, it is possible to ensure that the pilot tone is even tone. In this case, the pilot tone positions of resource units located so as to be symmetrical to the left and right with respect to the positions of the DC tones also have symmetry with respect to the DC tones.

Seventh Example

21 illustrates a tone plan of a 40 MHz channel according to a seventh embodiment of the present invention. Figures 21 (a) through 21 (e) correspond to the tone plans of Figures 18 (a) through 18 (e), respectively, and the tones of Figures 18 (a) through 18 (e) except for the position of some left over tones. It is substantially the same as the plan. Therefore, hereinafter, the tone plan proposed in FIG. 21 will be described in detail with reference to the difference from FIG. 18.

Referring to Figure 21 (a),

The first and second left over tones are left of the first resource unit,

The third and fourth left over tones are between the fourth and fifth resource units,

The fifth and sixth left over tones are between the fifth and sixth resource units,

The seventh to tenth left over tones are between the ninth and tenth resource units,

The eleventh and twelfth left over tones are between the thirteenth and fourteenth resource units;

The 13th and 14th left over tones are between the 14th and 15th resource units, and

The fifteenth and sixteenth left over tones may be located to the right of the eighteenth resource unit.

The seventh to tenth left over tones may be classified as DC tones. In this case, a total of nine (4 + 5) DC tones are located in the center frequency region of the 40 MHz channel. As the number of DC tones increases, there is an effect that it has robust performance in CFO measurement. According to the tone plan of this embodiment, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to Figure 21 (b),

The first and second left over tones are left of the first resource unit,

The third and fourth left over tones are between the second and third resource units,

The fifth and sixth left over tones are between the third and fourth resource units,

The seventh to tenth left over tones are between the fifth and sixth resource units,

The eleventh and twelfth left over tones are between the seventh and eighth resource units,

The 13th and 14th left over tones are between 8th and 9th resource units, and

The fifteenth and sixteenth left over tones may be located to the right of the tenth resource unit.

The seventh to tenth left over tones may be classified as DC tones. In this case, a total of nine (4 + 5) DC tones are located in the center frequency region of the 40 MHz channel. As the number of DC tones increases, there is an effect that it has robust performance in CFO measurement. According to the tone plan of this embodiment, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to Figure 21 (c),

The first and second left over tones are left of the first resource unit,

The third to sixth left over tones are between the third and fourth resource units, and

The seventh and eighth left over tones may be located to the right of the sixth resource unit.

The third to sixth left over tones may be classified as DC tones. In this case, a total of nine (4 + 5) DC tones are located in the center frequency region of the 40 MHz channel. As the number of DC tones increases, there is an effect that it has robust performance in CFO measurement. According to the tone plan of this embodiment, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Since FIG. 21 (d) is related to FIG. 18 (d) and FIG. 21 (e) is the same as described above with reference to FIG. 18 (e), overlapping descriptions are omitted.

Furthermore, as described above with respect to FIGS. 18A to 18E, the left tone plan and the right tone plan disclosed in FIGS. 21A to 21E may be combined to form a new tone plan. . In addition, the resource units of FIGS. 21 (a) to 21 (e) may be grouped into resource units in larger tones or may be divided into resource units in smaller tones to form a new tone plan.

In the case of the tone plan proposed in the seventh embodiment, due to at least one left over tone located at the edge of the resource units (26-tone resource unit, 52-tone resource unit, 106-tone resource unit), The effect is that interference is reduced. Further, according to the tone plan of the seventh embodiment, when using a 2x FFT size HE-LTF, pilot tone positions of resource units having the same number of tones located to correspond to each other on the left and right sides with respect to DC tones are the same. At the same time, it is possible to ensure that the pilot tone is even tone. In this case, the pilot tone positions of resource units located so as to be symmetrical to the left and right with respect to the positions of the DC tones also have symmetry with respect to the DC tones.

<Eighth Embodiment>

22 illustrates a tone plan of a 40 MHz channel according to an eighth embodiment of the present invention. Figures 22 (a) through 22 (e) correspond to the tone plans of Figures 18 (a) through 18 (e), respectively, and the tones of Figures 18 (a) through 18 (e) except for the position of some left over tones. It is substantially the same as the plan. Therefore, hereinafter, the tone plan proposed in FIG. 21 will be described in detail with reference to the difference from FIG. 17.

Referring to Figure 22 (a),

The first and second left over tones are between the second and third resource units,

The third left over tone is between the fourth and fifth resource units,

The fourth left over tone is between the fifth and sixth resource units,

The fifth and sixth left over tones are between the seventh and eighth resource units,

The seventh to tenth left over tones are between the ninth and tenth resource units,

The eleventh and twelfth left over tones are between the eleventh and twelfth resource units;

The 13th left over tone is between the 13th and 14th resource units,

The 14th left over tone is between the 14th and 15th resource units, and

The 15th and 16th left over tones may be located between the 16th and 17th resource units.

The seventh to tenth left over tones may be classified as DC tones. In this case, a total of nine (4 + 5) DC tones may be expressed in the center frequency region of the 40 MHz channel. As the number of DC tones increases, there is an effect that it has robust performance in CFO measurement. According to the tone plan of this embodiment, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to Figure 22 (b),

The first and second left over tones are between the first and second resource units,

The third left over tone is between the second and third resource units,

The fourth left over tone is between the third and fourth resource units,

The fifth and sixth left over tones are between the fourth and fifth resource units,

The seventh to tenth left over tones are between the fifth and sixth resource units,

The eleventh and twelfth left over tones are between the sixth and seventh resource units,

The thirteenth left over tone is between the seventh and eighth resource units;

The fourteenth left over tone is between the eighth and ninth resource units, and

The fifteenth and sixteenth left over tones may be located between the ninth and tenth resource units.

The seventh to tenth left over tones may be classified as DC tones. In this case, a total of nine (4 + 5) DC tones may be expressed in the center frequency region of the 40 MHz channel. As the number of DC tones increases, there is an effect that it has robust performance in CFO measurement. According to the tone plan of this embodiment, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to Figure 22 (c),

The first left over tone is between the first and second resource units,

The second left over tone is between the second and third resource units,

The third to sixth left over tones are between the third and fourth resource units,

The seventh left over tone is between the fourth and fifth resource units, and

The eighth left over tone may be located between the fifth and sixth resource units.

The third to sixth left over tones may be classified as DC tones. In this case, a total of nine (4 + 5) DC tones may be expressed in the center frequency region of the 40 MHz channel. As the number of DC tones increases, there is an effect that it has robust performance in CFO measurement. According to the tone plan of this embodiment, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Since FIG. 22D is related to FIG. 18D and FIG. 22E is the same as described above with respect to FIG. 18E, overlapping descriptions are omitted.

Furthermore, as described above with reference to FIGS. 18A to 18E, a new tone plan may be formed by combining the left tone plan and the right tone plan disclosed in FIGS. 22A to 22E. . In addition, the resource units of FIGS. 22 (a) to 22 (e) may be grouped into resource units in larger tones or may be divided into resource units in smaller tones to form a new tone plan.

The tone plan proposed in the eighth embodiment has the advantage that it can be copied and applied when the tone plan extension to the 80 MHz channel is applied.

3. 80 MHz channel tone plan

In an 802.11ax (or HE) system, a 4x FFT (4x is based on an existing 802.11ac system), the 80MHz channel in the frequency domain can include a total of 1024 (4 * 256) tones. Alternatively, since a 4x FFT (4x is based on an existing 802.11ac system) in an 802.11ax (or HE) system, a total of 1024 (4 * 256) tones may be located in an 80 MHz channel in the frequency domain. At this time, the tones of the 80MHz channel may be configured in the resource unit in units of n tones. Here, n means a natural number larger than zero. For example, the tones of the 80 MHz channel may be set in resource units in units of 26-tone, 52-tone, 106-tone, 242-tone, 484-tone, 996-tone.

In this case, 12 tones of the 1024 tones of the 80 MHz channel may be set as a left guard tone, 7 tones as a DC tone, and 11 tones as a right guard tones. . In the frequency domain, the left guard tones and the light guard tones can be located across the 80 MHz channel, and the DC tones can be located in the center frequency region of the 80 MHz channel. Thus, the number of tones that can be allocated substantially as a resource unit is 994-tons (= 1024-12-7-11).

However, when the frequency resource allocation unit is a 996-tone resource unit, five tones of 1024 tones may be set as a DC tone. In this case, the number of tones that can be allocated substantially as a resource unit is 996-tons (= 1024-12-5-11). This will be described later in detail.

When using a 26-tone resource unit as a unit for allocating a frequency resource of an 80 MHz channel, the 994-tone is 37 * 26 + 32. That is, a 994-tone of the 80 MHz channel can be divided into 37 26-tone resource units and 32 left over tones.

When using a 26-tone resource unit and a 52-tone resource unit as a unit for allocating frequency resources of an 80 MHz channel, the 994-tone becomes 16 * 52 + 5 * 26 + 32. That is, a 994-tone of the 80 MHz channel may be divided into sixteen 52-tone resource units, five 26-tone resource units, and 32 left over tones.

When using a 26-tone resource unit and a 106-tone resource unit as units for allocating frequency resources of an 80 MHz channel, the 994-tone is 8 * 106 + 5 * 26 + 16. That is, a 994-tone of an 80 MHz channel may be divided into eight 106-tone resource units, five 26-tone resource units, and sixteen left over tones.

When using a 26-tone resource unit and a 24-2-tone resource unit as a unit for allocating frequency resources of an 80 MHz channel, the 994-tone becomes 4 * 242 + 1 * 26. That is, a 994-tone of an 80 MHz channel may be divided into four 242-tone resource units and one 26-tone resource unit, and a left over tone may not exist.

When using a 26-tone resource unit and a 484-tone resource unit as a unit for allocating frequency resources of an 80 MHz channel, the 994-tone becomes 2 * 484 + 1 * 26. That is, a 994-tone of an 80 MHz channel may be divided into two 484-tone resource units and one 26-tone resource unit, and a left over tone may not exist.

When using a 996-tone resource unit (hereinafter, referred to as a '996-tone resource unit') as a unit for allocating a frequency resource of an 80 MHz channel, five DC tones may exist and the entire 996-tone may be one STA. Can be used as a resource unit assigned to. At this time, the left over tone may not exist.

In addition to the embodiments described above, the frequency resources of the 80 MHz channel include 26-tone resource units, 52-tone resource units, 106-tone resource units, and 242-tone resource units, 484-tone resource units, 996-tone resource units, and left. It can be divided into various combinations of overtones.

In particular, resource units in small tones divided as frequency resources in the 80 MHz channel may be grouped and re-divided into resource units in larger tones. For example, two 26-tone resource units are grouped into one 52-tone (26 + 26) resource unit, two 52-tone resource units and two left over tones are grouped into one 106-tone ( 2 * 52 + 2) resource unit, two 106-tone resource units, one 26-tone resource unit and four left over tones grouped together to form one 242-tone (2 * 106 + 26 + 4) resource Unit, two 242-tone resource units are grouped into one 484-tone (2 * 242) resource unit, two 484-tone resource units, one 26-tone resource unit, and two left over tones. Can be grouped into 996-ton (2 * 484 + 26 + 2) resource units. In this case, however, the centrally located 26-tone resource unit may not be used to construct a 52-tone resource unit and a 106-tone resource unit.

Therefore, even when the frequency resource is divided into 26-tone resource units as described above, the frequency resource is grouped into resource units of larger tones by grouping the 26-tone resource units and the left over tones into larger unit units. And left overtone.

In a similar manner, each of the resource units in large tones may be separated into resource units in small tones.

One or more resource units classified in the 80 MHz channel may be allocated to at least one STA as frequency resources.

Hereinafter, a tone plan regarding the position of left over tones generated by dividing a frequency resource (994-tone, or 996-tone) of an 80 MHz channel into resource unit units of the above-described tone size will be proposed.

<Ninth Embodiment>

FIG. 23 illustrates a tone plan of an 80 MHz channel according to a ninth embodiment of the present invention. FIG. 23 proposes a structure in which the tone plan of the fourth embodiment shown in FIG. 18 is substantially repeated twice. In the drawings, the left guard tone, the light guard tone, and the DC tone are not shown for convenience of description.

Referring to FIG. 23A, frequency resources of an 80 MHz channel may be divided into 37 resource units and 32 left over tones.

All 37 resource units may be 26-tone resource units. In this case, the fifth, fourteenth, nineteenth, twenty-fourth, and thirty-third resource units may be separated into two 13-tone sub-resource units, respectively, by left over tones located at the center.

The thirty-two left over tones (first to thirty-second left over tones) may be located between resource units in the frequency domain. E.g,

The first and second left over tones are between the second and third resource units,

The third to sixth left over tones are the center of the fifth resource unit (or between the 13-tone subresource units included in the fifth resource unit),

The seventh and eighth left over tones are between the seventh and eighth resource units,

The ninth and tenth left over tones are between the eleventh and twelfth resource units;

The eleventh to fourteenth left over tones are the center of the fourteenth resource unit (or between the 13-tone subresource units included in the fourteenth resource unit),

The 15th and 16th left over tones are between 16th and 17th resource units,

The 17th and 18th left over tones are between the 21st and 22nd resource units,

The 19th to 22nd left over tones are the center of the 24th resource unit (or between the 13-tone subresource units included in the 24th resource unit),

The 23rd and 24th left over tones are between the 26th and 27th resource units,

The 25th and 26th left over tones are between the 30th and 31st resource units,

The 27th to 30th left over tones are at the center of the 33rd resource unit (or between the 13-tone subresource units included in the 33rd resource unit), and

The 31st and 32nd left over tones are between the 35th and 36th resource units

It can be located at In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to FIG. 23B, frequency resources of an 80 MHz channel may be divided into 21 resource units and 32 left over tones.

Of the 21 resource units, the 1st, 2nd, 4th to 7th, 9th, 10th, 12th, 13th, 15th to 18th, 20th, and 21st resource units are 52-tone resource units. Can be. The third, eighth, eleventh, fourteenth, and nineteenth resource units may be 26-tone resource units. In this case, the third, eighth, eleventh, fourteenth, and nineteenth resource units may be separated into two 13-tone sub-resource units by centered left over tones, respectively.

The thirty-two left over tones (first to thirty-second left over tones) may be located between resource units in the frequency domain. E.g,

The first and second left over tones are between the first and second resource units,

The third to sixth left over tones are the center of the third resource unit (or between the 13-tone sub-resource units included in the third resource unit),

The seventh and eighth left over tones are between the fourth and fifth resource units,

The ninth and tenth left over tones are between the sixth and seventh resource units,

The eleventh to fourteenth left over tones are the center of the eighth resource unit (or between the 13-tone subresource units included in the eighth resource unit),

The 15th and 16th left over tones are between the 9th and 10th resource units,

The 17th and 18th left over tones are between the 12th and 13th resource units,

The 19th to 22nd left over tones are the center of the 14th resource unit (or between 13-tone subresource units included in the 14th resource unit),

The 23rd and 24th left over tones are between the 15th and 16th resource units,

The 25th to 26th left over tones are between the 17th and 18th resource units,

The 27th to 30th left over tones are the center of the 19th resource unit (or between the 13-tone subresource units included in the 19th resource unit), and

The 31st and 32nd left over tones may be located between the 20th and 21st resource units. In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to FIG. 23C, frequency resources of an 80 MHz channel may be divided into 13 resource units and 16 left over tones.

The first, third, fourth, sixth, eighth, tenth, eleventh, and thirteenth resource units of the thirteen resource units may be 106-tone resource units. The second, fifth, seventh, ninth, and twelfth resource units may be 26-tone resource units. In this case, the second, fifth, seventh, ninth, and twelfth resource units may be separated into two 13-tone sub resource units, respectively, by left over tones located at the center.

Sixteen left over tones (first to sixteen left over tones) may be located between resource units in the frequency domain. E.g,

The first to fourth left over tones are at the center of the second resource unit (or between 13-tone subresource units included in the second resource unit),

The fifth to eighth left over tones are the center of the fifth resource unit (or between the 13-tone subresource units included in the fifth resource unit),

The ninth to twelfth left over tones are the center of the ninth resource unit (or between the 13-tone subresource units included in the fifth resource unit), and

The thirteenth to sixteenth left over tones may be located at the center of the twelfth resource unit.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to FIG. 23 (d), an 80 MHz channel may be divided into a total of five frequency resources and there is no left over tone. At this time, the first, second, fourth, and fifth resource units of the five frequency resources may be 242-tone resource units. And the third resource unit may be a 26-tone resource unit. In this case, the third resource unit may be separated into two 13-tone sub resource units by centered left over tones.

Referring to FIG. 23E, an 80 MHz channel may be divided into three frequency resources, and there is no left over tone. In this case, the first and third resource units of the three frequency resources may be a 484-tone resource unit. And the second resource unit may be a 26-tone resource unit.

Referring to FIG. 23 (f), an 80 MHz channel may be divided into a total of one resource unit, and a left over tone may not exist. At this time, one resource unit may be a 996-tone resource unit.

Furthermore, the tone plans of FIGS. 23A to 23F described above may be combined or modified in various forms to form new tone plans.

As one example, resource units in smaller tones may be grouped into resource units in larger tones to form a new tone plan. More specifically, two 26-tone resource units are one 52-tone resource unit, two 52-tone resource units and two left over tones are one 106-tone resource unit, two 106-tone resource units. Tone resource units, one 26-tone resource unit and four left over tones into one 242-tone resource unit, two 242-tone resource units into 484-tone resource units, two 484-tone resource units , One 26-tone resource unit, and two left over tones may be grouped into one 996-tone resource unit. However, centrally located 26-tone resource units may not be used to be grouped into resource units in large tones. In the case of applying the above-described grouping scheme, various tone plans may be derived from the tone plans of FIGS. 23A to 23E.

For example, if the above-described grouping scheme is applied to Fig. 22 (a), one 106-tone resource unit (grouping four 26-tone resource units and two left over tones) + one 13-tone Sub-resource unit + 4 left over tones + 1 13-tone sub-resource unit + 1 52-tone resource unit (grouping 2 26-tone resource units) + 2 left over tones + 1 52-tone resource Unit (grouping two 26-tone resource units) + one 242-tone resource unit (grouping nine 26-tone resource units and eight left over tones) + one 26-tone resource unit + 484-ton A new tone plan consisting of resource units can be derived.

Similarly, each of the resource units in large tones may be separated into resource units in small tones to form a new tone plan.

As another example, in the tone plans of FIGS. 23 (a) to 23 (f), the tone plan on the left (hereinafter referred to as the 'left tone plan') and the tone plan on the right (hereinafter referred to as the 'right tone plan') are different from each other. May be combined to form a new tone plan. For example, a new tone plan can be formed by combining the left tone plan of FIG. 23 (d) and the right tone plan of FIG. 23 (e). In this case, the newly formed tone plan may consist of two 242-tone resource units + one 26-tone resource unit + one 484-tone resource unit.

That is, the tone plans of Figs. 18 (a) to 18 (e) can be combined with each other, and the resource units are grouped into resource units in larger tones or separated into smaller resource units in new tones. A plan can be derived.

According to the tone plan of the ninth embodiment as described above, when using a 2x FFT size HE-LTF, the pilot tone positions of the resource units having the same number of tones positioned to correspond to the left and the right on the basis of DC tones are the same. At the same time as designing, it is possible to ensure that the pilot tone is even tone. In this case, the pilot tone positions of resource units located so as to be symmetrical to the left and right with respect to the positions of the DC tones also have symmetry with respect to the DC tones.

<Example 10>

24 illustrates a tone plan of an 80 MHz channel according to a tenth embodiment of the present invention. FIG. 24 proposes a structure in which the fifth embodiment of FIG. 18 is repeated twice. Also, Figs. 24A to 24F correspond to the tone plans of Figs. 23A to 23F, respectively, and Figs. 23A to 23F except for the positions of some left over tones. Is substantially the same as the tone plan. Therefore, hereinafter, the tone plan proposed in FIG. 24 will be described in detail with reference to the difference from FIG. 23.

Referring to Figure 24 (a),

The first and second left over tones are between the second and third resource units,

Between the fourth and fifth resource units of the third and fourth left overtones,

The fifth and sixth left over tones are between the fifth and sixth resource units,

The seventh and eighth left over tones are between the seventh and eighth resource units,

The ninth and tenth left over tones are between the eleventh and twelfth resource units;

The eleventh and twelfth left over tones are between the thirteenth and fourteenth resource units;

The 13th and 14th left over tones are between the 14th and 15th resource units,

The 15th and 16th left over tones are between 16th and 17th resource units,

The 17th and 18th left over tones are between the 21st and 22nd resource units,

The 19th and 20th left over tones are between the 23rd and 24th resource units,

The 21st and 22nd left over tones are between the 24th and 25th resource units,

The 23rd and 24th left over tones are between the 26th and 27th resource units,

The 25th and 26th left over tones are between the 30th and 31st resource units,

The 27th and 28th left over tones are between the 32nd and 33rd resource units,

The 29th and 30th left over tones are between the 33rd and 34th resource units, and

The 31st and 32nd left over tones may be located between the 35 th and 36 th resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to Figure 24 (b),

The first and second left over tones are between the first and second resource units,

Between the second and third resource units of the third and fourth left overtones,

The fifth and sixth left over tones are between the third and fourth resource units,

The seventh and eighth left over tones are between the fourth and fifth resource units,

The ninth and tenth left over tones are between the sixth and seventh resource units,

The eleventh and twelfth left over tones are between the seventh and eighth resource units,

The 13th and 14th left over tones are between 8th and 9th resource units,

The 15th and 16th left over tones are between the 9th and 10th resource units,

The 17th and 18th left over tones are between the 12th and 13th resource units,

The 19th and 20th left over tones are between the 13th and 14th resource units,

The 21st and 22nd left over tones are between the 14th and 15th resource units,

The 23rd and 24th left over tones are between the 15th and 16th resource units,

The 25th and 26th left over tones are between the 17th and 18th resource units,

The 27th and 28th left over tones are between the 18th and 19th resource units,

The 29th and 30th left over tones are between the 19th and 20th resource units, and

The 31st and 32nd left over tones may be located between the 20th and 21st resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to FIG. 24 (c),

The first and second left over tones are between the first and second resource units,

Between the second and third resource units of the third and fourth left overtones,

The fifth and sixth left over tones are between the fourth and fifth resource units,

The seventh and eighth left over tones are between the fifth and sixth resource units,

The ninth and tenth left over tones are between the eighth and ninth resource units;

The eleventh and twelfth left over tones are between the ninth and tenth resource units;

The 13th and 14th left over tones are between the 11th and 12th resource units, and

The 15th and 16th left over tones may be located between the 12th and 13th resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

24 (d) is related to FIG. 23 (d), FIG. 24 (e) is related to FIG. 23 (e), and FIG. 24 (f) is the same as described above with reference to FIG. 23 (f). Duplicate explanations are omitted.

Further, as described above with reference to FIGS. 23A to 23F, a new tone plan may be formed by combining the left tone plan and the right tone plan disclosed in FIGS. 24A to 24F. . In addition, the resource units of FIGS. 24 (a) to 24 (f) may be grouped into resource units in larger tones or may be divided into resource units in smaller tones to form a new tone plan.

The tone plan proposed in the tenth embodiment has an advantageous effect in terms of PAPR of the STF sequence. In addition, in the tone plan proposed in the tenth embodiment, the interference between the resource units is reduced due to at least one left over tone located between the 52-tone resource units. Further, according to the tone plan of the tenth embodiment, when using a 2x FFT size HE-LTF, the pilot tone positions of the resource units having the same number of tones located to correspond to the left and the right on the basis of DC tones are the same. At the same time, it is possible to ensure that the pilot tone is even tone. In this case, the pilot tone positions of resource units located so as to be symmetrical to the left and right with respect to the positions of the DC tones also have symmetry with respect to the DC tones.

<Eleventh embodiment>

25 illustrates a tone plan of an 80 MHz channel according to an eleventh embodiment of the present invention. FIG. 25 proposes a structure in which the sixth embodiment of FIG. 20 is repeated twice. 25 (a) to 25 (f) correspond to the tone plans of FIGS. 23 (a) to 23 (f), respectively, and FIGS. 23 (a) to 23 (f) except for the positions of some left over tones. Is substantially the same as the tone plan. Therefore, hereinafter, the tone plan proposed in FIG. 25 will be described in detail with reference to FIG. 23.

Referring to Figure 25 (a),

The first and second left over tones are left of the first resource unit,

Between the second and third resource units of the third and fourth left overtones,

The fifth and sixth left over tones are between the seventh and eighth resource units,

The seventh to tenth left over tones are between the ninth and tenth resource units,

The eleventh and twelfth left over tones are between the eleventh and twelfth resource units;

The 13th and 14th left over tones are between 16th and 17th resource units,

The 15th and 16th left over tones are between the 18th and 19th resource units,

The 17th and 18th left over tones are between the 19th and 20th resource units,

The 19th and 20th left over tones are between the 21st and 22nd resource units,

The 21st and 22nd left over tones are between the 26th and 27th resource units,

The 23rd to 26th left over tones are between the 28th and 29th resource units,

The 27th and 28th left over tones are between the 30th and 31st resource units,

The 29th and 30th left over tones are between the 35th and 36th resource units, and

The 31st and 32nd left over tones may be located to the right of the 37 th resource unit.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to Figure 25 (b),

The first and second left over tones are left of the first resource unit,

Between the first and second resource units of the third and fourth left overtones,

The fifth and sixth left over tones are between the fourth and fifth resource units,

The seventh to tenth left over tones are between the fifth and sixth resource units,

The eleventh and twelfth left over tones are between the sixth and seventh resource units,

The 13th and 14th left over tones are between the 9th and 10th resource units,

The 15th and 16th left over tones are between the 11th and 12th resource units,

The 17th and 18th left over tones are between the 12th and 13th resource units,

The 19th and 20th left over tones are between the 13th and 14th resource units,

The 21st and 22nd left over tones are between the 16th and 17th resource units,

The 23rd to 26th left over tones are between the 17th and 18th resource units,

The 27th and 28th left over tones are between the 18th and 19th resource units,

The 29th and 30th left over tones are between the 21st and 22nd resource units, and

The 31st and 32nd left over tones may be located to the right of the 22nd resource unit.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to Figure 25 (c),

The first and second left over tones are left of the first resource unit,

Between the third and fourth left over tones third and fourth resource units,

The seventh and eighth left over tones are between the sixth and seventh resource units,

The ninth and tenth left over tones are between the seventh and eighth resource units,

The eleventh to fourteenth left over tones are between the tenth and eleventh resource units, and

The fifteenth and sixteenth left over tones may be located to the right of the thirteenth resource unit.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

25 (d) is related to FIG. 23 (d), FIG. 25 (e) is related to FIG. 23 (e), and FIG. 25 (f) is the same as described above with reference to FIG. 23 (f). Duplicate explanations are omitted.

Furthermore, as described above with reference to FIGS. 23A to 23F, a new tone plan may be formed by combining the left tone plan and the right tone plan disclosed in FIGS. 25A to 25F. . In addition, the resource units of FIGS. 25 (a) to 25 (f) may be grouped into resource units in larger tones or may be divided into resource units in smaller tones to form a new tone plan.

In the tone plan proposed in the eleventh embodiment, due to at least one left over tone located between resource units (26-tone resource unit, 52-tone resource unit, 106-tone resource unit), The effect is that interference is reduced. Further, in the tone plan proposed in the eleventh embodiment, the interference between adjacent channels is reduced due to at least one left over tone located between adjacent channels. Further, according to the tone plan of the eleventh embodiment, when using a 2x FFT size HE-LTF, the pilot tone positions of the resource units having the same number of tones positioned to correspond to the left and the right on the basis of DC tones are the same. At the same time, it is possible to ensure that the pilot tone is even tone. In this case, the pilot tone positions of resource units located so as to be symmetrical to the left and right with respect to the positions of the DC tones also have symmetry with respect to the DC tones.

<Twelfth Example>

FIG. 26 illustrates a tone plan of an 80 MHz channel according to a twelfth embodiment of the present invention. FIG. 26 proposes a structure in which the seventh embodiment of FIG. 21 is repeated twice. Also, FIGS. 26A to 26F correspond to the tone plans of FIGS. 23A to 23F, respectively, and FIGS. 23A to 23F except for the positions of some left over tones. Is substantially the same as the tone plan. Therefore, hereinafter, the tone plan proposed in FIG. 26 will be described in detail with reference to FIG. 23.

Referring to Figure 26 (a),

The first and second left over tones are left of the first resource unit,

Between the fourth and fifth resource units of the third and fourth left overtones,

The fifth and sixth left over tones are between the fifth and sixth resource units,

The seventh to tenth left over tones are between the ninth and tenth resource units,

The eleventh and twelfth left over tones are between the thirteenth and fourteenth resource units;

The 13th and 14th left over tones are between the 14th and 15th resource units,

The 15th and 16th left over tones are between the 18th and 19th resource units,

The 17th and 18th left over tones are between the 19th and 20th resource units,

The 19th and 20th left over tones are between the 23rd and 24th resource units,

The 21st and 22nd left over tones are between the 24th and 25th resource units,

The 23rd to 26th left over tones are between the 28th and 29th resource units,

The 27th and 28th left over tones are between the 32nd and 33rd resource units,

The 29th and 30th left over tones are between the 33rd and 34th resource units, and

The 31st and 32nd left over tones may be located to the right of the 37 th resource unit.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to Figure 26 (b),

The first and second left over tones are left of the first resource unit,

Between the second and third resource units of the third and fourth left overtones,

The fifth and sixth left over tones are between the third and fourth resource units,

The seventh to tenth left over tones are between the fifth and sixth resource units,

The eleventh and twelfth left over tones are between the seventh and eighth resource units,

The 13th and 14th left over tones are between 8th and 9th resource units,

The 15th and 16th left over tones are between the 10th and 11th resource units,

The 17th and 18th left over tones are between the 11th and 12th resource units,

The 19th and 20th left over tones are between the 13th and 14th resource units,

The 21st and 22nd left over tones are between the 14th and 15th resource units,

The 23rd to 26th left over tones are between the 16th and 17th resource units,

The 27th and 28th left over tones are between the 18th and 19th resource units,

The 29th and 30th left over tones are between the 19th and 20th resource units, and

The 31st and 32nd left over tones may be located to the right of the 21st resource unit.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to Figure 26 (c),

The first and second left over tones are left of the first resource unit,

Between the third and fourth left over tones third and fourth resource units,

The seventh and eighth left over tones are between the sixth and seventh resource units,

The ninth and tenth left over tones are between the seventh and eighth resource units,

The eleventh to fourteenth left over tones are between the tenth and eleventh resource units, and

The fifteenth and sixteenth left over tones may be located to the right of the thirteenth resource unit.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

26 (d) is related to FIG. 23 (d), FIG. 26 (e) is related to FIG. 23 (e), and FIG. 26 (f) is the same as described above with reference to FIG. 23 (f). Duplicate explanations are omitted.

Furthermore, as described above with reference to FIGS. 23A to 23F, a new tone plan may be formed by combining the left tone plan and the right tone plan disclosed in FIGS. 26A to 26F. . In addition, the resource units of FIGS. 26 (a) to 26 (f) may be grouped into resource units in larger tones or may be divided into resource units in smaller tones to form a new tone plan.

In the tone plan proposed in the twelfth embodiment, due to at least one left over tone located between resource units (26-tone resource unit, 52-tone resource unit, 106-tone resource unit), The effect is that interference is reduced. Further, in the tone plan proposed in the twelfth embodiment, the interference between adjacent channels is reduced due to at least one left over tone located between adjacent channels. Further, according to the tone plan of the twelfth embodiment, when using a 2x FFT size HE-LTF, the pilot tone positions of the resource units having the same number of tones located to correspond to the left and the right on the basis of DC tones are the same. At the same time, it is possible to ensure that the pilot tone is even tone. In this case, the pilot tone positions of resource units located so as to be symmetrical to the left and right with respect to the positions of the DC tones also have symmetry with respect to the DC tones.

<Thirteenth Example>

27 shows a tone plan of an 80 MHz channel according to a thirteenth embodiment of the present invention. FIG. 27 proposes a structure to which the eighth embodiment of FIG. 22 is applied. 27 (a) to 27 (f) correspond to the tone plans of FIGS. 23 (a) to 23 (f), respectively, and FIGS. 23 (a) to 23 (f) except for the positions of some left over tones. Is substantially the same as the tone plan. Therefore, hereinafter, the tone plan proposed in FIG. 27 will be described in detail with reference to the difference from FIG. 23.

Referring to Figure 27 (a),

The first and second left over tones are between the second and third resource units,

The third left over tone is between the fourth and fifth resource units,

The fourth left over tone is between the fifth and sixth resource units,

The fifth and sixth left over tones are between the seventh and eighth resource units,

The seventh and eighth left over tones are between the 9th and 10th resource units,

The ninth and tenth left over tones are between the eleventh and twelfth resource units;

The eleventh left over tone is between the 13th and 14th resource units,

The 12th left over tone is between the 14th and 15th resource units,

The 13th and 14th left over tones are between 16th and 17th resource units,

The 15th and 16th left over tones are between the 18th and 19th resource units,

The 17th and 18th left over tones are between the 19th and 20th resource units,

The 19th and 20th left over tones are between the 21st and 22nd resource units,

The 21st left over tone is between the 23rd and 24th resource units;

The 22nd left over tone is between the 24th and 25th resource units,

The 23rd and 24th left over tones are between the 26th and 27th resource units,

The 25th and 26th left over tones are between the 28th and 29th resource units,

The 27th and 28th left over tones are between the 30th and 31st resource units,

The 29th left over tone is between the 32nd and 33rd resource units,

The thirtieth left over tone is between the 33rd and 34th resource units, and

The 31st and 32nd left over tones may be located between the 35 th and 36 th resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to Figure 27 (b),

The first and second left over tones are between the first and second resource units,

The third left over tone is between the second and third resource units,

The fourth left over tone is between the third and fourth resource units,

The fifth and sixth left over tones are between the fourth and fifth resource units,

The seventh and eighth left over tones are between the fifth and sixth resource units,

The ninth and tenth left over tones are between the sixth and seventh resource units,

The eleventh left over tone is between the seventh and eighth resource units,

The 12th left over tone is between the 8th and 9th resource units,

The 13th and 14th left over tones are between the 9th and 10th resource units,

The 15th and 16th left over tones are between the 10th and 11th resource units,

The 17th and 18th left over tones are between the 11th and 12th resource units,

The 19th and 20th left over tones are between the 12th and 13th resource units,

The 21st left over tone is between the 13th and 14th resource units;

The 22nd left over tone is between the 14th and 15th resource units,

The 23rd and 24th left over tones are between the 15th and 16th resource units,

The 25th and 26th left over tones are between the 16th and 17th resource units,

The 27th and 28th left over tones are between the 17th and 18th resource units,

The 29th left over tone is between the 18th and 19th resource units;

The thirtieth left over tone is between the 19th and 20th resource units, and

The 31st and 32nd left over tones may be located between the 20th and 21st resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to Figure 27 (c),

The first left over tone is between the first and second resource units,

The second left over tone is between the second and third resource units,

The third and fourth left over tones are between the third and fourth resource units,

The fifth left over tone is between the fourth and fifth resource units,

The sixth left over tone is between the fifth and sixth resource units,

The seventh and eighth left over tones are between the sixth and seventh resource units,

The ninth and tenth left over tones are between the seventh and eighth resource units,

The eleventh left over tone is between an eighth and a ninth resource unit,

The 12th left over tone is between the 9th and 10th resource units,

The 13th and 14th left over tones are between the 10th and 11th resource units,

The fifteenth left over tone is between the eleventh and twelfth resource units, and

The sixteenth left over tone may be located between the twelfth and thirteenth resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

27 (d) is related to FIG. 23 (d), FIG. 27 (e) is related to FIG. 23 (e), and FIG. 27 (f) is the same as described above with reference to FIG. 23 (f). Duplicate explanations are omitted.

Furthermore, as described above with reference to FIGS. 23A to 23F, a new tone plan may be formed by combining the left tone plan and the right tone plan disclosed in FIGS. 27A to 27F. . In addition, the resource units of FIGS. 27 (a) to 27 (f) may be grouped into resource units in larger tones or may be divided into resource units in smaller tones to form a new tone plan.

In the tone plan proposed in the thirteenth embodiment, the resource units (26-tone resource unit, 52-tone resource unit, 106-tone resource unit) are located between the resource units due to at least one left over tone. The effect is that interference is reduced. In addition, the tone plan proposed in the thirteenth embodiment has an advantageous effect in terms of PAPR of the STF sequence.

<Example 14>

28 illustrates a tone plan of an 80 MHz channel according to a fourteenth embodiment of the present invention. FIG. 28 proposes a structure in which the eighth embodiment of FIG. 22 is repeated twice. Also, FIGS. 28 (a) to 28 (f) correspond to the tone plans of FIGS. 23 (a) to 23 (f) respectively, and FIGS. 23 (a) to 23 (f) except for the positions of some left over tones. Is substantially the same as the tone plan. Therefore, hereinafter, the tone plan proposed in FIG. 28 will be described in detail with reference to the difference from FIG. 23.

Referring to Figure 28 (a),

The first and second left over tones are between the second and third resource units,

The third left over tone is between the fourth and fifth resource units,

The fourth left over tone is between the fifth and sixth resource units,

The fifth and sixth left over tones are between the seventh and eighth resource units,

The seventh to tenth left over tones are between the ninth and tenth resource units,

The eleventh and twelfth left over tones are between the eleventh and twelfth resource units;

The 13th left over tone is between the 13th and 14th resource units,

The 14th left over tone is between the 14th and 15th resource units,

The 15th and 16th left over tones are between 16th and 17th resource units,

The 17th and 18th left over tones are between the 21st and 22nd resource units,

The 19th left over tone is between the 23rd and 24th resource units;

The 20th left over tone is between the 24th and 25th resource units,

The 21st and 22nd left over tones are between the 26th and 27th resource units,

The 23rd to 26th left over tones are between the 28th and 29th resource units,

The 27th and 28th left over tones are between the 30th and 31st resource units,

The 29th left over tone is between the 32nd and 33rd resource units,

The thirtieth left over tone is between the 33rd and 34th resource units, and

The 31st and 32nd left over tones may be located between the 35 th and 36 th resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to Figure 28 (b),

The first and second left over tones are between the first and second resource units,

The third left over tone is between the second and third resource units,

The fourth left over tone is between the third and fourth resource units,

The fifth and sixth left over tones are between the fourth and fifth resource units,

The seventh to tenth left over tones are between the fifth and sixth resource units,

The eleventh and twelfth left over tones are between the sixth and seventh resource units,

The thirteenth left over tone is between the seventh and eighth resource units;

The 14th left over tone is between 8th and 9th resource units,

The 15th and 16th left over tones are between the 9th and 10th resource units,

The 17th and 18th left over tones are between the 12th and 13th resource units,

The 19th left over tone is between the 13th and 14th resource units;

The 20th left over tone is between the 14th and 15th resource units,

The 21st and 22nd left over tones are between the 15th and 16th resource units,

The 23rd to 26th left over tones are between the 16th and 17th resource units,

The 27th and 28th left over tones are between the 17th and 18th resource units,

The 29th left over tone is between the 18th and 19th resource units;

The thirtieth left over tone is between the 19th and 20th resource units, and

The 31st and 32nd left over tones may be located between the 20th and 21st resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Referring to Figure 28 (c),

The first left over tone is between the first and second resource units,

The second left over tone is between the second and third resource units,

The third to sixth left over tones are between the third and fourth resource units,

The seventh left over tone is between the fourth and fifth resource units,

The eighth left over tone is between the fifth and sixth resource units,

The ninth left over tone is between the eighth and ninth resource units;

The tenth left over tone is between the ninth and tenth resource units;

The eleventh to fourteenth left over tones are between the tenth and eleventh resource units,

The fifteenth left over tone is between the eleventh and twelfth resource units, and

The sixteenth left over tone may be located between the twelfth and thirteenth resource units.

In this case, the symmetry between the tone plan in the left frequency region and the tone plan in the right frequency region is satisfied with respect to the center frequency region.

Since FIG. 28 (d) is related to FIG. 23 (d), FIG. 28 (e) is related to FIG. 23 (e), and FIG. 28 (f) is the same as described above with reference to FIG. 23 (f), Duplicate explanations are omitted.

Furthermore, as described above with reference to FIGS. 23A to 23F, a new tone plan may be formed by combining the left tone plan and the right tone plan disclosed in FIGS. 28A to 28F. . In addition, the resource units of FIGS. 28 (a) to 28 (f) may be grouped into resource units in larger tones or may be divided into resource units in smaller tones to form a new tone plan.

In the tone plan proposed in the fourteenth embodiment, due to at least one left over tone located between resource units (26-tone resource unit, 52-tone resource unit, 106-tone resource unit), The effect is that interference is reduced.

In the above, the tone plan regarding the position of the left over tones for each channel has been described in detail.

Based on the above, the present invention can classify resource units according to a preset tone plan disclosed in each figure. Furthermore, a new tone plan can be derived by grouping resource units into resource units in larger tones or separating them into resource units in smaller tones based on the tone plans disclosed in each drawing. Further, a new tone plan can also be derived by combining or repeating the tone plans disclosed in each drawing.

In this case, the at least one left over tone may be located between the resource units, at the edge of the resource units, or next to the resource units. If the left over tone is located between the resource units, interference between the resource units can be prevented. If the left over tone is located at the edge of the resource units, interference from adjacent channels can be prevented. In addition, according to the position of the left over tone is classified as a DC tone, a left guard tone, or a light guard tone, it is also possible to perform the corresponding function. In addition, various effects (eg, even tone guarantee of pilot tone, PAPR reduction, etc.) may occur depending on the position of the left over tone. Therefore, the above-described embodiments in consideration of each effect may be selectively applied or combined. In addition, it is not necessarily limited to the above-mentioned embodiment, A free application is possible within the range which a person skilled in the art accepts.

29 is a flowchart illustrating a data transmission method of an STA apparatus according to an embodiment of the present invention. The embodiments described above with reference to the flowchart can be equally applied. Therefore, a description overlapping with the above description will be omitted.

Referring to FIG. 29, the STA may generate a PPDU (S2910). In this case, the transport channel of the PPDU may include a plurality of resource units and a plurality of left over tones in the frequency domain. Alternatively, the frequency resource of the transport channel of the PPDU may be divided into a plurality of resource units and a plurality of left over tones.

Each of the plurality of resource units may include a preset number of tones. For example, each of the plurality of resource units may include 26-tons, 106-tons, 242-tons, 484-tons, or 996-tons. The plurality of left over tones may be located between the plurality of resource units in the frequency domain based on a preset tone plan. Herein, the preset tone plan is the same as described above with reference to FIGS. 14 to 28.

Next, the STA may transmit a PPDU (S2920). In more detail, the STA may transmit the generated PPDU to at least one other STA assigned with the frequency resource of the PPDU transmission channel.

30 is a block diagram of each STA apparatus according to an embodiment of the present invention.

In FIG. 30, the STA apparatus 3000 may include a memory 3010, a processor 3020, and an RF unit 3030. As described above, the STA device 3000 is a HE STA device and may be an AP or a non-AP STA.

The RF unit 3030 may be connected to the processor 3020 to transmit / receive a radio signal. The RF unit 3030 may up-convert data received from the processor into a transmission / reception band to transmit a signal.

The processor 3020 may be connected to the RF unit 3030 to implement a physical layer and / or a MAC layer according to the IEEE 802.11 system. The processor 3020 may be configured to perform an operation according to various embodiments of the present disclosure according to the drawings and description described above. In addition, a module implementing the operation of the STA 3000 according to various embodiments of the present disclosure described above may be stored in the memory 3010 and executed by the processor 3020.

The memory 3010 is connected to the processor 3020 and stores various information for driving the processor 3020. The memory 3010 may be included in the processor 3020 or may be installed outside the processor 3020 and connected to the processor 3020 by known means.

In addition, the STA apparatus 3000 may include a single antenna or multiple antennas.

The detailed configuration of the STA apparatus 3000 of FIG. 30 may be implemented such that the matters described in the above-described various embodiments of the present invention are applied independently or two or more embodiments are simultaneously applied.

31 illustrates a portion of a STA device in more detail according to an embodiment of the present invention.

In FIG. 31, the STA apparatus includes an FEC encoder 3110, a mapper 3120, a pilot insertion unit 3130, an IDFT unit 3140, and an analog / RF unit 3150. In FIG. 31, an FEC encoder 3110, a mapper 3120, a pilot insertion unit 3130, and an IDFT unit 3140 may be included in the processor 3020 of FIG. 30, and the analog / RF unit 3150 is shown in FIG. It may correspond to the 30 RF unit 3030. The STA device of FIG. 31 may perform the above-described operation of the HE STA.

The Forward Error Correction (FEC) encoder 3110 may output the encoded data bits by encoding the data bits according to a predetermined encoding scheme. Here, the FEC encoder 3110 may be implemented as a convolutional encoder, a turbo encoder, or a low density parity check encoder (LDPC) as an error correction code. The FEC encoder 3110 may perform binary convolutional code (BCC) encoding as a convolutional encoder.

The mapper 3120 may perform constellation mapping. In other words, the mapper 3120 may output a modulation symbol (that is, a constellation point) by modulating the data bit according to a predetermined modulation scheme. That is, the encoded data bits may be divided into bit blocks by the mapper 3120, and each bit block may be mapped to modulation symbols representing positions according to constellations having amplitudes and phases. There is no restriction on a modulation scheme in the mapper 3120, and m-Phase Shift Keying (m-PSK) or m-Quardrature Amplitude Modulation (m-QAM) may be used.

The pilot insertion unit 3130 may insert a pilot in the transmission data. In other words, the pilot insertion unit 3130 may insert pilot tones into subcarriers according to a predetermined number and position.

The IDFT unit 3140 may perform IDFT on the data. In other words, the IDFT unit 3140 may perform IFFT or IDFT on the modulation symbols output from the mapper 3120 to output OFDM symbol data in a time domain.

The analog / RF unit 3150 may up-convert the complex baseband waveform to transmit an RF signal. In other words, the analog / RF unit 3150 may transmit a transmission signal by upconverting the data / signal processed in the baseband, and may be referred to as an RF unit.

The embodiments described above are the components and features of the present invention are combined in a predetermined form. Each component or feature is to be considered optional unless stated otherwise. Each component or feature may be embodied in a form that is not combined with other components or features. It is also possible to combine some of the components and / or features to form an embodiment of the invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is obvious that the claims may be combined to form an embodiment by combining claims that do not have an explicit citation relationship in the claims or as new claims by post-application correction.

Embodiments according to the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of a hardware implementation, an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), FPGAs ( field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, procedure, function, etc. that performs the functions or operations described above. The software code may be stored in memory and driven by the processor. The memory may be located inside or outside the processor, and may exchange data with the processor by various known means.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the essential features of the present invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

Various embodiments have been described in the best mode for carrying out the invention.

In the wireless communication system of the present invention, the data transmission and reception method has been described with reference to the example applied to the IEEE 802.11 system, but it is possible to apply to various wireless communication systems in addition to the IEEE 802.11 system.

Claims (16)

1. In the data transmission method of the STA (Station) device of a WLAN (Wireless LAN) system,

   Generating a physical protocol data unit (PPDU) including a physical preamble and a data field; And

   Transmitting the PPDU; Including,

   The transport channel of the PPDU includes a plurality of resource units and a plurality of left over tones in the frequency domain,

   And the plurality of left over tones are located between the plurality of resource units in the frequency domain based on a tone plan per channel.
2. The method of claim 1,

   If the transmission channel is a 20 MHz channel,

   And the plurality of left over tones consist of four left over tones.
3. The method of claim 2,

   When the plurality of resource units includes nine resource units each consisting of 26-tones,

   The first left over tone is between the second and third resource units, and

   The second left over tone is located between the seventh and eighth resource units.
4. The method of claim 2,

   When the plurality of resource units includes one resource unit composed of 26-tones and four resource units each composed of 52-tones,

   The first left over tone is between the first and second resource units, and

   The second left over tone is located between the fourth and fifth resource units.
5. The method of claim 4, wherein

   The first, second, fourth, and fifth resource units are resource units each composed of the 52-tones,

   And a third resource unit is one resource unit composed of the 26-tones.
6. The method of claim 2,

   Seven DC tones are located in the center frequency region of the 20MHz channel, STA data transmission method.
7. The method of claim 1,

   The transmission channel is a 40 MHz channel,

   If the plurality of resource units includes 18 resource units each consisting of 26-tones, the plurality of left over tones are composed of 16 left over tones,

   If the plurality of resource units includes two resource units each composed of the 26-tones and eight resource units each consisting of 52-tones, the plurality of left over tones are composed of the sixteen left over tones and , And

   When the plurality of resource units includes two resource units each configured of the 26-tones and four resource units each consisting of 106-tones, the plurality of left over tones are configured of eight left over tones, Data transmission method of the STA device.
8. The method of claim 7, wherein

   If the plurality of resource units includes 18 resource units each configured of the 26-tone,

   The first and second left over tones are between the second and third resource units,

   The third left over tone is between the fourth and fifth resource units,

   The fourth left over tone is between the fifth and sixth resource unit,

   The fifth and sixth left over tones are between the seventh and eighth resource units,

   The seventh and eighth left over tones are between the 9th and 10th resource units,

   The ninth and tenth left over tones are between the 11th and 12th resource units,

   The eleventh left over tone is between the 13th and 14th resource units,

   A twelfth left over tone is between the 14th and 15th resource units, and

   The thirteenth and fourteenth left over tones are located between the sixteenth and seventeenth resource units.
9. The method of claim 7, wherein

   When the plurality of resource units includes two resource units each configured to the 26-tones and eight resource units each configured to the 52-tones,

   The first and second left over tones are between the first and second resource units,

   The third left over tone is between the second and third resource units,

   The fourth left over tone is between the third and fourth resource units,

   The fifth and sixth left over tones are between the fourth and fifth resource units,

   The seventh and eighth left over tones are between the fifth and sixth resource units,

   A ninth and tenth left over tone is between the sixth and seventh resource units,

   The eleventh left over tone is between the seventh and eighth resource units,

   A twelfth left over tone is between the eighth and ninth resource units, and

   A thirteenth and fourteenth left over tone are located between the ninth and tenth resource units.
10. The method of claim 9,

    The first, second, fourth, fifth, sixth, seventh, ninth, and tenth resource units are resource units each composed of the 52-tones,

    And the third and eighth resource units are resource units each configured of the 26-tones.
11. The method of claim 7, wherein

    When the plurality of resource units includes two resource units each configured of the 26-tones and four resource units each comprised of the 106-tones,

    The first left over tone is between the first and second resource units,

    The second left over tone is between the second and third resource units,

    The third and fourth left over tones are between the third and fourth resource units,

    A fifth left over tone is between the fourth and fifth resource units, and

    The sixth left over tone is located between the fifth and sixth resource units.
12. The method of claim 11,

    Wherein the first, third, fourth, and sixth resource units are resource units composed of the 106-tones, and the second and fifth resource units are resource units composed of the 26-tones, respectively. Data transfer method.
13. The method of claim 7, wherein

    5 DC tones are located in the center frequency region of the 40MHz channel, STA data transmission method.
14. The method of claim 7, wherein

    The tone plan of the 40 MHz channel is repeatedly applied to the tone plan of the 80 MHz channel, STA data transmission method.
15. The method of claim 14,

    7 DC tones are located in the center frequency region of the 80MHz channel, STA data transmission method.
16. In the STA (Station) device of a wireless LAN (WLAN) system,

    A radio frequency (RF) unit for transmitting and receiving radio signals; And

    A processor for controlling the RF unit; Including,

    The processor generates a physical protocol data unit (PPDU) including a physical preamble and a data field, and transmits the PPDU using the RF unit,

    The transport channel of the PPDU includes a plurality of resource units and a plurality of left over tones in the frequency domain,

    And the plurality of left over tones are located between the plurality of resource units in the frequency domain based on a channel-specific tone plan.

Images