Patent Description:
Although the below-described signal transmission methods are applicable various wireless communication systems, a wireless local area network (WLAN) system will be described as an example of a system, to which the present invention is applicable.

Standards for the WLAN technology have been developed as Institute of Electrical and Electronics Engineers (IEEE) <NUM> standards. IEEE <NUM>. 11a and b use an unlicensed band at <NUM> or <NUM>. IEEE <NUM>. 11b provides a transmission rate of <NUM> Mbps and IEEE <NUM>. 11a provides a transmission rate of <NUM> Mbps. IEEE <NUM> provides a transmission rate of <NUM> Mbps by applying Orthogonal Frequency Division Multiplexing (OFDM) at <NUM>. IEEE <NUM>. 11n provides a transmission rate of <NUM> Mbps for four spatial streams by applying Multiple Input Multiple Output (MIMO)-OFDM. IEEE <NUM>. 11n supports a channel bandwidth of up to <NUM> and, in this case, provides a transmission rate of <NUM> Mbps.

Since the above-described standards for the WLAN technology maximally use bandwidth of <NUM> and support eight spatial streams, IEEE <NUM>. 11ax standardization is being discussed in addition to IEEE <NUM>. 11ac standard maximally supporting a rate of <NUM> Gbit/s.

<CIT> discloses a method of receiving a physical layer convergence procedure (PLCP) protocol data unit (PPDU) by an access point (AP) in a wireless local area (LAN) system. In the document the method is described to include: allocating a first transmission channel bandwidth to a first station (STA) which is multiple input multiple output (MIMO)-paired with the AP, allocating a second transmission channel bandwidth to a second STA which is MIMO-paired with the AP, transmitting to the first STA and the second STA a sync trigger for determining a time point at which the first STA transmits a first PPDU and a time point at which the second STA transmits a second PPDU, and receiving simultaneously the first PPDU and the second PPDU from the first STA and the second STA.

<CIT> discloses a method for transmitting a data frame through a channel including a plurality of sub-channels by a sender in a wireless local area network (WLAN) system. In the document the method is described to comprise acquiring first channel state information on each of the plurality of sub-channels from a first receiver, allocating at least one first allocation sub-channel of the plurality of sub-channels to the first receiver on the basis of the first channel state information, acquiring second channel state information on each of the plurality of sub-channels from a second receiver if the at least one first allocation sub-channel corresponds to a portion of a plurality of channels, allocating at least one second allocation sub-channel of the plurality of sub-channels to the second receiver on the basis of the second channel state information, and transmitting a data unit to the first receiver and the second receiver.

<CIT> discloses systems and techniques relating to wireless local area network devices. In the document the systems and techniques are described to include determining wireless resource allocations in a time domain, a spatial wireless channel domain, and a frequency domain to coordinate communications with wireless communication devices, generating a control frame that directs wireless communications based on at least a portion of the wireless resource allocations, and transmitting the control frame to the wireless communication devices.

An object of the present invention is to provide a method of, at a station, efficiently transmitting a signal in a wireless communication system and an apparatus therefor.

More specifically, in IEEE <NUM>. 11ax which is a next-generation wireless local area network (WLAN) among wireless communication systems, a resource allocation method using orthogonal frequency divisional multiple access (OFDMA) or multi-user multiple input multiple output (MIMO) is efficiently defined.

Another object of the present invention is to acquire various effects understood from the detailed description of the present invention in addition to the above-described object.

According to the present invention, a station can efficiently transmit a signal in a wireless communication system. More specifically, in IEEE <NUM>. 11ax which is a next-generation wireless local area network (WLAN) among wireless communication systems, it is possible to efficiently perform a resource allocation method using orthogonal frequency divisional multiple access (OFDMA) or multi-user multiple input multiple output (MIMO).

The effects which can be obtained by the present invention are not limited to the above-described effects and other effects which are not described herein will become apparent to those skilled in the art from the following description.

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The detailed description set forth below in connection with the appended drawings is intended as a description of exemplary embodiments and is not intended to represent the only embodiments in which the concepts explained in these embodiments can be practiced. The detailed description includes details for the purpose of providing an understanding of the present invention. However, it will be apparent to those skilled in the art that these teachings may be implemented and practiced without these specific details.

The following embodiments are proposed by combining constituent components and characteristics of the present invention according to a predetermined format. The individual constituent components or characteristics should be considered to be optional factors on the condition that there is no additional remark. If required, the individual constituent components or characteristics may not be combined with other components or characteristics. Also, some constituent components and/or characteristics may be combined to implement the embodiments of the present invention. The order of operations to be disclosed in the embodiments of the present invention may be changed to another. Some components or characteristics of any embodiment may also be included in other embodiments, or may be replaced with those of the other embodiments as necessary.

It should be noted that specific terms disclosed in the present invention are proposed for convenience of description and better understanding of the present invention, and the use of these specific terms may be changed to another format within the technical scope of the present invention.

In some instances, well-known structures and devices are omitted in order to avoid obscuring the concepts of the present invention and the important functions of the structures and devices are shown in block diagram form. The same reference numbers will be used throughout the drawings to refer to the same or like parts.

Exemplary embodiments of the present invention are supported by standard documents disclosed for at least one of radio access systems including an Institute of Electrical and Electronics Engineers (IEEE) <NUM> system, a <NUM>rd Generation Project Partnership (3GPP) system, a 3GPP Long Term Evolution (LTE) system, and a 3GPP2 system. In particular, the steps or parts, which are not described to clearly reveal the technical idea of the present invention, in the embodiments of the present invention may be supported by the above documents. All terminology used herein may be supported by at least one of the above-mentioned documents.

The following technologies can be applied to a variety of radio access technologies, for example, CDMA (Code Division Multiple Access), FDMA (Frequency Division Multiple Access), TDMA (Time Division Multiple Access), OFDMA (Orthogonal Frequency Division Multiple Access), SC-FDMA (Single Carrier Frequency Division Multiple Access), and the like. CDMA may be embodied as wireless (or radio) technology such as UTRA (Universal Terrestrial Radio Access) or CDMA2000. TDMA may be embodied as wireless (or radio) technology such as GSM (Global System for Mobile communications)/GPRS (General Packet Radio Service)/EDGE (Enhanced Data Rates for GSM Evolution). OFDMA may be embodied as wireless (or radio) technology such as Institute of Electrical and Electronics Engineers (IEEE) <NUM> (Wi-Fi), IEEE <NUM> (WiMAX), IEEE <NUM>-<NUM>, and E-UTRA (Evolved UTRA).

In the entire specification, when a certain portion "includes" a certain component, this indicates that the other components are not excluded, but may be further included unless specially described. The terms "unit", "-or/er" and "module" described in the specification indicate a unit for processing at least one function or operation, which may be implemented by hardware, software and a combination thereof.

<FIG> is a diagram illustrating an exemplary configuration of a WLAN system.

As illustrated in <FIG>, the WLAN system includes at least one Basic Service Set (BSS). The BSS is a set of STAs that are able to communicate with each other by successfully performing synchronization.

An STA is a logical entity including a physical layer interface between a Media Access Control (MAC) layer and a wireless medium. The STA may include an AP and a non-AP STA. Among STAs, a portable terminal manipulated by a user is the non-AP STA. If a terminal is simply called an STA, the STA refers to the non-AP STA. The non-AP STA may also be referred to as a terminal, a Wireless Transmit/Receive Unit (WTRU), a User Equipment (UE), a Mobile Station (MS), a mobile terminal, or a mobile subscriber unit.

The AP is an entity that provides access to a Distribution System (DS) to an associated STA through a wireless medium. The AP may also be referred to as a centralized controller, a Base Station (BS), a Node-B, a Base Transceiver System (BTS), or a site controller.

The BSS may be divided into an infrastructure BSS and an Independent BSS (IBSS).

The BSS illustrated in <FIG> is the IBSS. The IBSS refers to a BSS that does not include an AP. Since the IBSS does not include the AP, the IBSS is not allowed to access to the DS and thus forms a self-contained network.

<FIG> is a diagram illustrating another exemplary configuration of a WLAN system.

BSSs illustrated in <FIG> are infrastructure BSSs. Each infrastructure BSS includes one or more STAs and one or more APs. In the infrastructure BSS, communication between non-AP STAs is basically conducted via an AP. However, if a direct link is established between the non-AP STAs, direct communication between the non-AP STAs may be performed.

As illustrated in <FIG>, the multiple infrastructure BSSs may be interconnected via a DS. The BSSs interconnected via the DS are called an Extended Service Set (ESS). STAs included in the ESS may communicate with each other and a non-AP STA within the same ESS may move from one BSS to another BSS while seamlessly performing communication.

The DS is a mechanism that connects a plurality of APs to one another. The DS is not necessarily a network. As long as it provides a distribution service, the DS is not limited to any specific form. For example, the DS may be a wireless network such as a mesh network or may be a physical structure that connects APs to one another.

<FIG> is a diagram illustrating an exemplary structure of a WLAN system. <FIG> shows an example of an infrastructure BSS including a DS.

In the example of <FIG>, BSS1 and BSS2 configure an ESS. In the WLAN system, a station operates according to MAC/PHY rules of IEEE <NUM>. The station includes an AP station and a non-AP station. The non-AP station corresponds to an apparatus directly handled by a user, such as a laptop or a mobile telephone. In the example of <FIG>, a station <NUM>, a station <NUM> and a station <NUM> are non-AP stations and a station <NUM> and a station <NUM> are AP stations.

In the following description, the non-AP station may be referred to as a terminal, a wireless transmit/receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile terminal, a mobile subscriber station (MSS), etc. In addition, the AP corresponds to a base station (BS), a node-B, an evolved node-B (eNB), a base transceiver system (BTS), a femto BS, etc. in different wireless communication fields.

<FIG> are diagrams illustrating an example of a frame structure used in an IEEE <NUM> system.

An STA may receive a physical layer packet data unit (PPDU). At this time, the PPDU frame format may include a short training field (STF), a long training field (LTF), a signal (SIG) field and a data field. At this time, for example, the PPDU frame format may be set based on the type of the PPDU frame format.

For example, a non-high throughput (HT) PPDU frame format may include a legacy-STF (L-STF), a legacy-LTF (L-LTF), an SIG field and a data field.

In addition, any one of an HT-mixed format PPDU and an HT-Greenfield format PPDU may be set as the type of the PPDU frame format. At this time, in the above-described PPDU format, additional (different types of) STFs, LTFs and SIG fields may be included between the SIG field and the data field.

In addition, referring to <FIG>, a very high throughput (VHT) PPDU format may be set. At this time, even in the VHT PPDU format, additional (different types of) STFs, LTFs and SIG fields may be included between the SIG field and the data field. More specifically, in the VHT PPDU format, at least one of a VHT-SIG-A field, a VHT-STF field, a VHT-LTF field and a VHT SIG-B field may be included between the L-SIG field and the data field.

At this time, the STF is a signal for signal detection, automatic gain control (AGC), diversity selection, accurate time synchronization, etc. and the LTF is a signal for channel estimation, frequency error estimation, etc. A combination of the STF and the LTF may be referred to as a PLCP preamble and the PLCP preamble may refer to a signal for synchronization and channel estimation of an OFDM physical layer.

Referring to <FIG>, the SIG field may include a RATE field and a LENGTH field. The RATE field may include information about modulation and coding rate of data. The LENGTH field may include information about the length of data. Additionally, the SIG field may include a parity bit, an SIG TAIL bit, etc..

The data field may include a SERVICE field, a PLCP service data unit (PSDU) and a PPDU Tail bit and further may include a padding bit if necessary.

Referring to <FIG>, some bits of the SERVICE field may be used for synchronization of a descrambler in a receiver, and some bits may be composed of reserved bits. The PSDU corresponds to a MAC protocol data unit (PDU) defined at a MAC layer and may include data created/used at a higher layer. The PPDU TAIL bit may be used to return an encoder to a zero state. The padding bit may be used to adjust the length of the data field to a predetermined length.

In addition, for example, as described above, the VHT PPDU format may include the additional (different types of) STF, LTF and SIG fields. At this time, in the VHT PPDU, L-STF, L-LTF and L-SIG may be a part of non-VHT of the VHT PPDU. At this time, in the VHT PPDU, VHT-SIG-A, VHT-STF, VHT-LTF and VHT-SIG-B may be part of VHT. That is, in the VHT PPDU, regions for a Non-VHT field and a VHT field may be defined. At this time, for example, VHT-SIG-A may include information for interpreting the VHT PPDU.

At this time, for example, referring to <FIG>, VHT-SIG-A may be composed of VHT SIG-A1 ((a) of <FIG>) and VHT SIG-A2 ((b) of <FIG>). At this time, each of VHT SIG-A1 and VHT SIG-A2 may include <NUM> data bits and VHT SIG-A1 may be transmitted earlier than VHT SIG-A2. At this time, VHT SIG-A1 may include a BW field, an STBC field, a Group ID field, an NSTS/Partial AID field, a TXOP_PS_NOT_ALLOWED field and a Reserved field. In addition, VHT SIG-A2 may include a Short GI field, a Short GI NSYM Disambiguation field, an SU/MU[<NUM>] Coding field, an LDPC Extra OFDM Symbol field, an SU VHT-MCS/MU[<NUM>-<NUM>] Coding field, a Beamformed field, a CRC field, a Tail field and a Reserved field. Through this, information on the VHT PPDU may be confirmed.

<FIG> is a diagram showing an example of a PPDU format which may be used in the present invention.

As described above, various types of PPDU formats may be set. At this time, as an example, a new type of PPDU format may be proposed. The PPDU may include an L-STF field, an L-STF field, an L-SIG field and a data field. For example, a PPDU frame may further include a high efficiency (HE) SIG-A field, a HE-STF field, a HE-LTF field and a HE SIG-B field. For example, the HE SIG-A field may include common information. For example, the common information may include a bandwidth field, a guard interval (GI) field, a length field and a BSS color field. For example, an L-part (L-STF, L-LTF and L-SIG) may be transmitted in the form of an SFN in units of <NUM> in the frequency domain. In addition, for example, the HE SIG-A field may be transmitted in the form of an SFN in units of <NUM>, similarly to the L part. For example, if a channel is greater than <NUM>, the L parts and the HE SIG-A field may be duplicated and transmitted in units of <NUM>. In addition, the HE SIG-B field may be UE-specific information. For example, the user-specific information may include station AID, resource allocation information (e.g., allocation size), MCS, Nsts, coding, STBC, TXBF, etc. For example, the HE SIG-B field may be transmitted over the full bandwidth.

For example, referring to (b) of <FIG>, the PPDU may be transmitted through a band of <NUM>. At this time, the L part and the HE SIG-A part may be duplicated and transmitted in units of <NUM> and the HE SIG-B field may be transmitted over the full bandwidth of <NUM>. However, the above-described transmission method is exemplary and is not limited to the above-described embodiments.

<FIG> is a diagram illustrating an uplink among the concepts of multi-user transmission applicable to the present invention.

As described above, the AP may acquire a TXOP for accessing a medium, occupy the medium through contention and transmit a signal. Referring to <FIG>, an AP station may transmit a trigger frame to a plurality of stations in order to perform UL MU transmission. At this time, for example, the trigger frame may include information on resource allocation location and size, station IDs, MCS, and MU type (=MIMO or OFDMA). That is, uplink multi-user (UL MU) transmission may mean that a plurality of stations as multiple users performs uplink transmission to the AP station. At this time, the AP station may transmit the trigger frame to the plurality of stations such that the plurality of stations performs uplink data transmission.

The plurality of stations may transmit data to the AP after an SIFS has elapsed, based on a format indicated by the trigger frame. Thereafter, the AP may transmit ACK/NACK information to the station and perform UL MU transmission.

<FIG> is a diagram illustrating a station transmitting data using only some bandwidths according to an embodiment of the present invention.

As shown in <FIG>, when the STA transmits a frame, the frame is transmitted using only a partial bandwidth, not a full bandwidth. For example, as shown in <FIG>, the STA may transmit the frame with a bandwidth (e.g., <NUM>) less than <NUM>. In this case, a good subband of <NUM> in <NUM> may be selected and used to transmit the frame.

In <FIG>, the STA transmits data through a second <NUM>-MHz subband. At this time, the STA may transmit, in HE-SIGs, information on through which subband data is transmitted. For example, in the bandwidth information included in HE-SIG, a reception side may be informed of through which subband data is transmitted, through a bitmap of a minimum resource granularity unit.

In the above example, if a resource unit is <NUM> (e.g., <NUM> subcarrier tones), since a resource allocation bitmap having a size of <NUM> bits is configured and transmission is performed through a second resource unit (or subband), the bitmap is <NUM> (that is, the frame is transmitted using the second resource unit only). At this time, the bandwidth may be set to <NUM>.

In association with the above description, hereinafter, examples of a minimum resource granularity unit will be described.

The second resource unit indicates a small resource unit and a method of allocating left/right guard tones for interference mitigation to both ends of a BW and allocating an RRU and an IRU to the remaining region except for central DC tones is defined. If possible, the number of left/right guard tones and DC tones may be maintained regardless of BW (e.g., left/right guard tone = <NUM>/<NUM> or <NUM>/<NUM> tones, DC = <NUM> or <NUM> tones, etc.).

An allocation method and the number of allocated tones may be set in consideration of resource use efficiency, scalability according to BW, etc. In addition, the second resource unit may be predefined and may be delivered through signaling (e.g., SIG) among various methods.

In this method, the size of the RRU/BTU is <NUM> subcarrier tones.

<FIG> is a diagram showing an example of defining a minimum resource allocation unit regardless of bandwidth.

Since <NUM> subcarriers are equal to basic OFDM numerology of <NUM> in a legacy Wi-Fi system, a conventional interleaver may be reused. At this time, the size of the IRU/STU is <NUM> subcarrier tones. That is, assume that RRU/BTU = <NUM> and IRU/STU = <NUM>. However, assume that the minimum allocation unit of the IRU/STU is <NUM> IRUs/STUs (i.e., <NUM> tones).

Table <NUM> below shows the number of RUs, IRUs, and DCs and GIs per BW.

As shown in Table <NUM> above, the number of remaining tones, that is, the number of DCs and GSs, is maintained as <NUM> (twice the number of IRU tones) regardless of BW.

If the IRU has a size of <NUM> subcarriers, per-BW numerology may be as shown in Table <NUM> below. A <NUM>-MHz BW is obtained by repeatedly applying <NUM> twice.

In addition to the above-described examples, various combinations of (RU, IRU) are possible as follows. For example, (RU, IRU) = (<NUM>, <NUM>), (RU, IRU) = (<NUM>, <NUM>), (RU, IRU) = (<NUM>, <NUM>), etc. may also be possible.

(RRU= <NUM>/<NUM>/<NUM> for <NUM>/<NUM>/<NUM>, IRU=<NUM>)
In this method, the IRU is fixed to <NUM> regardless of BW. If two pilot signals are used, <NUM> data tones are advantageous for various MCS decoding methods. In particular, <NUM> is advantageous for systematic design because RRU+IRU=<NUM>+<NUM>=<NUM> is a divisor of <NUM>.

The following tables show values which may be defined for each bandwidth. More specifically, Table <NUM> shows <NUM>, Table <NUM> shows <NUM> and Table <NUM> shows <NUM>.

Hereinafter, a method of efficiently configuring resource allocation information based on the above description will be described.

As described above with respect to <FIG>, in one embodiment of the present invention, when data is transmitted to a plurality of STAs for OFDMA/MU-MIMO transmission, assume that subbands which are not used for data transmission are included in the full bandwidth. In this state, the resource allocation information may include a common resource allocation bitmap for the plurality of STAs and indication information indicating subbands which are not used for data transmission in the full frequency band.

Hereinafter, examples of indicating the above-described resource allocation information using the HE-SIG field will be described.

As shown in Table <NUM> above, the resource allocation information may include a common resource allocation bitmap for a plurality of STAs. The resource allocation bitmap may indicate a subband configuration, which is a resource allocation unit of the entire frequency band, depending on whether a subsequent bit is toggled from a preceding bit in the resource allocation bitmap. More specifically, if a first subsequent bit is not toggled from a first preceding bit in the resource allocation bitmap, a subband (e.g., SB <NUM>) corresponding to the first preceding bit and a subband (e.g., SB <NUM>) corresponding to the first subsequent bit may be allocated to the same STA. In contrast, if a second subsequent bit is toggled from a second preceding bit in the resource allocation bitmap, a subband (e.g., SB <NUM>) corresponding to the second preceding bit and a subband (e.g., SB <NUM>) corresponding to the second subsequent bit may be allocated to different STAs.

The resource allocation bitmap may start from <NUM> or <NUM> and Table <NUM> shows an example in which the resource allocation starts from <NUM>. In the example of Table <NUM>, since a bit subsequent to <NUM> which is a first bit is toggled to <NUM>, a first SB <NUM> and a second SB2 are allocated to different STA. In addition, since "<NUM>", which is a third bit, is toggled from the preceding bit, the SB <NUM> is allocated to an STA different from the STA, to which the SB <NUM> is allocated. In contrast, since "<NUM>", which is a fourth bit, is not togged from the preceding bit, an SB <NUM> corresponding thereto is allocated to the same STA as the SB <NUM> corresponding to the preceding bit.

In summary, (<NUM>) SB <NUM> is allocated to STA <NUM>, (<NUM>) SB <NUM> is allocated to STA <NUM>, and (<NUM>) SBs <NUM> and <NUM> are allocated to STA3. If a toggling based bitmap is used, it is possible to efficiently and flexibly allocate resources while reducing signaling overhead of the plurality of STAs. In the above description, it is assumed that the resource allocation order of the STAs may be predetermined in order of STA <NUM>, <NUM> and <NUM> or signaled in advance.

The above-described resource allocation information may include the number of allocated streams (Nsts), space-time block coding (STBC), modulation and coding scheme (MCS) as per-user control information as shown in Table <NUM>.

As a modification of Table <NUM>, instead of the resource allocation bitmap, a start offset and an allocation size may be indicated as follows.

The signaling method shown in Table <NUM> above may cause a problem in the following situations.

<FIG> is a diagram illustrating a method of configuring resource allocation information according to a preferred embodiment of the present invention.

As shown in <FIG>, when an AP transmits a trigger frame for UL MU (OFDMA), only a specific band may be used. Resource use information may be included and transmitted in the trigger frame.

If it is assumed that SB <NUM> and SB <NUM> are allocated to STA <NUM> and SB <NUM> is allocated to STA <NUM> as shown in <FIG> and, for convenience, resources are allocated to the plurality of STAs by STA number, the toggling based bitmap may be "<NUM>", because SBs <NUM> and <NUM> are allocated to the same STA, SB3 configures an allocation unit different from that of SBs <NUM> and <NUM> and SB4 configures an allocation unit different from that of SB3.

If presence of unused SBs in the entire band is not indicated as shown in <FIG>, the bitmap may be erroneously interpreted as (<NUM>) allocation of SBs <NUM> and <NUM> to STA <NUM>, (<NUM>) allocation of SB <NUM> to STA <NUM> and (<NUM>) allocation of SB <NUM> to STA <NUM>.

Accordingly, in one preferred embodiment of the present invention, indication information, indicating subbands which are not used for data transmission, may be further included and a null allocation field indicating whether a subband preceding a subband allocated to a corresponding STA of a plurality of STAs is a null subband may be included.

More specifically, upon UL MU transmission, when the AP transmits a trigger frame to allocate UL OFDMA resources (frame transmission region), a specific subband may be allocated to the STA through subband operation (the STA may perform transmission using a specific subband). At this time, which subband is used and which subband is not used (null resource allocation) may be indicated in the trigger frame.

That is, <FIG> shows that resource allocation information may have a user-specific information field and a user common information field, the user-specific information field may indicate presence/absence of "Null allocation" in each of N STAs and AID and per-STA specific parameter information as an STA identifier, and the above-described resource allocation bitmap information may be included as user common information.

On such an assumption, the situation of <FIG> is applied. In the example of <FIG>, a third band is not used. Accordingly, if resource allocation is indicated in the form of a bitmap, the following configuration is possible. At this time, if the value of the null allocation field is <NUM>, it is assumed that null allocation is present before allocation of the AID, but definition of the field value may be changed.

In Table <NUM>, although the bitmap may be determined to be "<NUM>" as described above, presence of null allocation before allocation to STA <NUM> may be indicated as null allocation information. Therefore, the bitmap may not be erroneously interpreted as (<NUM>) allocation of SBs <NUM> and <NUM> to STA <NUM>, (<NUM>) allocation of SB <NUM> to STA <NUM> and (<NUM>) allocation of SB <NUM> to STA <NUM>, but may be accurately interpreted as (<NUM>) allocation of SBs <NUM> and <NUM> to STA <NUM>, (<NUM>) null allocation of SB <NUM> and (<NUM>) allocation of SB <NUM> to STA <NUM>, as shown in <FIG>.

<FIG> are diagrams showing additional examples for thorough understanding of an embodiment of the present invention.

As shown in <FIG>, in the case of UL OFDMA allocation, in the trigger frame, the resource allocation bitmap is set to <NUM> and the null allocation fields are all set to <NUM> as shown in the following table.

In <FIG>, it can be implicitly seen from the information of Table <NUM> that last allocation is null allocation. As shown in <FIG>, if <NUM>-MHz bands are all allocated to STAs <NUM>, <NUM> and <NUM>, resource allocation information shown in Table <NUM> below may be transmitted.

<FIG> shows an example of transmitting a frame using a bandwidth of <NUM>.

In <FIG>, a frame is transmitted with a bandwidth of <NUM>, the size of a resource unit (or subband) is <NUM> (e.g., <NUM> tones), and a total number of resource units is <NUM>. At this time, OFDMA resources are allocated to three STAs and a seventh resource unit (subband) is a null allocation unit.

In this example, the size of the resource allocation bitmap is <NUM> bits and the values of the null allocation field and the resource allocation bitmap field may be set as follows.

Hereinafter, various modifications of the above-described embodiment will be described.

First, instead of inserting the null allocation field to every ID, a null allocation bitmap may be used as follows.

The size of the null allocation bitmap may be equal to the resource allocation bitmap to indicate which subband (e.g., resource unit) is a null allocation unit. In <FIG>, the sizes of the resource allocation bitmap and the null allocation bitmap may be <NUM> bits.

In <FIG>, the sizes of the resource allocation bitmap and the null allocation bitmap may be <NUM> bits. The following table shows the example (N=<NUM>) of <FIG>.

The size of the null allocation bitmap may be set to a total number of allocations including null allocation. If the allocation bitmap is included, the size of the null allocation bitmap is determined based on information on the allocation bitmap (the number of toggles + <NUM>).

If the number of allocations in the resource allocation bitmap and the number of AIDs are equal, the null allocation bitmap may not be included. In this case, this may be indicated through a <NUM>-bit flag as follows.

Alternatively, if the number of allocations and the number of AIDs are not equal or the number of allocations is greater than the number of AIDs, the null allocation bitmap may be included. If the number of allocations in the resource allocation bitmap and the number of AIDs are equal, the null allocation bitmap may not be included.

If resource allocation is indicated in the form of an allocation size, not in the form of a bitmap, similar definition is possible.

AID may be included only when null allocation is not performed (<NUM>). Allocation information is included by the total number of allocations including null allocation.

The following table shows an example of applying <FIG>.

Instead of the null allocation field, a specific value which is not used for AID is used for indication. That is, an unallocated value may be used. For example, if all AID bits are set to <NUM> or <NUM>, this indicates a null allocation value.

The following table shows an example of applying the above-described method to <FIG>.

Meanwhile, instead of the null allocation field, the null allocation bitmap may be used.

The size of the null allocation bitmap may be determined by a total number of resource units.

The following table shows an example of <FIG> when the size of the null allocation bitmap is determined by the total number of resource units.

Which resource unit is a null allocation bitmap may be checked through the null allocation bitmap.

The null allocation bitmap may be configured by the total number of allocations including null allocation, instead of the resource units and indicate how many allocations are present before null allocation. For example, when the total number of allocations including null allocation is <NUM>, the null allocation bitmap has <NUM> bits, a bit corresponding to null allocation is set to <NUM> and a bit which does not correspond to null allocation is set to <NUM>, and vice versa (that is, a bit corresponding to null allocation is set to <NUM> and a bit which does not correspond to null allocation is set to <NUM>). A total number of allocations may be delivered to the STA through HE-SIG.

The above-defined field information (e.g., number of STAs/allocation (N/M), AID, allocation bitmap, null allocation field, null allocation bitmap, NA bitmap presences, etc.) may be included and transmitted in the trigger frame (CTX) carrying an SIG field or resource allocation information or may be transmitted through another frame.

As described above, the proposed methods may be used not only for UL frame transmission but also for DL frame transmission (DL OFDMA/MU(SU)-MIMO).

<FIG> is a diagram illustrating a method of configuring resource allocation information when DL/UL OFDMA transmission and DL/UL MU-MIMO transmission are used interchangeably in another embodiment of the present invention.

In the example of <FIG>, a frame corresponding to STA <NUM> is transmitted through resource units (RUs) <NUM>, <NUM>, <NUM> and <NUM> (<NUM>) and frames corresponding to STA <NUM>, STA <NUM>, STA4 and STA <NUM> are transmitted through RUs <NUM> and <NUM> (<NUM>) using MU-MIMO and frames corresponding to STA <NUM> and STA <NUM> are transmitted through RUs <NUM> and <NUM> (<NUM>). At this time, resources may be allocated using the following method.

Method <NUM>: Resources are allocated to STAs through the AIDs of the STAs. An example thereof is as follows.

MU indication: This indicates whether allocation of an STA for AID is transmitted using MU-MIMO. A first STA having MU-MIMO indication of <NUM> becomes a first STA of an MU-MIMO region. MU-MIMO indication of <NUM> indicates SU transmission.

If MU indication for a preceding STA is set to <NUM>, an STA having MU indication of <NUM> uses the same resources as the preceding STA. If MU indication for a preceding STA is set to <NUM>, an STA having MU indication of <NUM> uses a next resource region of a resource region of the preceding STA. The STA may acquire a resource region used thereby through a resource allocation bitmap. The following table shows an example of applying such a method to <FIG>.

Through the resource allocation bitmap set to <NUM>, it can be seen that a total of four resources is allocated and STAs <NUM>, <NUM> and <NUM> are set to MU indication of <NUM> such that SU transmission is performed and STAs <NUM>, <NUM> and <NUM> perform transmission using the same resources as STA <NUM> using MU-MIMO.

Since the number of contiguous <NUM> of the MU indication is indicated as one MU-MIMO allocation unit and <NUM> indicates one SU-MIMO indication, STAs may know a total number of allocations through MU indication information. That is, the total number of allocations is (the total number of MU indications (<NUM>) + the number of groups of contiguous MU indications (<NUM>)). In the above example, since the number of MU indications (<NUM>) is <NUM> and the number of groups of contiguous MU indications (<NUM>) is <NUM>, the total number of allocations is <NUM>.

Another example of using MU indication will now be described.

MU indication: This indicates whether allocation of an STA for AID is transmitted using MU-MIMO. MU-MIMO indication of <NUM> indicates SU transmission. A first MU STA has MU indication of <NUM> and an STA having MU indication of <NUM> uses the same resources as the preceding STA. If MU indication for a preceding STA is set to <NUM>, an STA having MU indication of <NUM> uses a next resource region of a resource region used by the preceding STA. The STA may acquire a resource region used thereby through a resource allocation bitmap. The following table shows an example of applying such a method to <FIG>.

Instead of the resource allocation bitmap, an allocation size may be used.

With respect to MU-MIMO, a necessary number of pieces of STA information (e.g., AID, MIMO info (Nsts, STBC, etc.)) may be included.

Method <NUM>: When resources are allocated to STAs, one resource is allocated to a single user (e.g., STAs <NUM>, <NUM> and <NUM> of <FIG>) through the AID of the single STA and allocation of MU-MIMO (STAs <NUM>, <NUM>, <NUM> and <NUM> of <FIG>) uses GID.

Instead of including MU-MIMO indication in each STA, the number of resource allocations may be indicated in the form of a bitmap. A total number of resource allocations may be directly included in HE-SIG or may be checked by the UE based on the resource allocation bitmap.

Each bit of the bitmap indicates whether the resource unit corresponding to the resource allocation corresponding to each bit is allocated using MU-MIMO or SU. Accordingly, the size of the MU-MIMO indication bitmap is determined by the total number of allocations of the resource allocation bitmap. For example, if the total number of allocated OFDMA resources is <NUM>, the MU-MIMO indication bitmap has <NUM> bits and indicates which resource allocation unit uses MU-MIMO.

In addition, null allocation indication and MU allocation may be used together as follows.

Another use example is as follows.

In MU-MIMO, if GID is used instead of AID and the allocation size is used instead of the allocation bitmap, the resource allocation information may be configured as follows.

<FIG> is a block diagram showing an exemplary configuration of an access point (AP) apparatus (or a base station apparatus) and a station apparatus (or UE apparatus) according to an embodiment of the present invention.

The AP <NUM> may include a processor <NUM>, a memory <NUM> and a transceiver <NUM>. The STA <NUM> may include a processor <NUM>, a memory <NUM> and a transceiver <NUM>.

The transceivers <NUM> and <NUM> may transmit/receive a radio frequency (RF) signal and implement a physical layer according to an IEEE <NUM> system, for example. The processors <NUM> and <NUM> may be respectively connected to the transceivers <NUM> and <NUM> to implement a physical layer and/or a MAC layer according to the IEEE <NUM> system. The processors <NUM> and <NUM> may be configured to perform operations according to combinations of one or more of the various embodiments of the present invention described above. In addition, modules for implementing operations of the AP and the STA according to the above-described embodiments of the present invention may be stored in the memories <NUM> and <NUM> and may be executed by the processors <NUM> and <NUM>, respectively. The memories <NUM> and <NUM> may be mounted inside or outside the processors <NUM> and <NUM> to be connected to the processors <NUM> and <NUM> by known means, respectively.

The description of the AP apparatus <NUM> and the STA apparatus <NUM> is applicable to the base station apparatus and the UE apparatus in other wireless communication systems (e.g., LTE/LTE-A systems).

The detailed configurations of the AP and the STA apparatuses may be implemented such that details described in the above embodiments of the present invention are independently applied or two or more embodiments are simultaneously applied. In this case, overlapping details have been omitted from the description for clarity.

<FIG> is a diagram showing an exemplary structure of a processor of an AP apparatus or a station apparatus according to an embodiment of the present invention.

The processor of the AP or the STA may have a plurality of layers. <NUM> shows a MAC sublayer <NUM> of a data link layer (DLL) and a physical (PHY) layer <NUM> among the plurality of layers. As shown in <FIG>, the PHY <NUM> may include a physical layer convergence procedure (PLCP) entity <NUM> and a physical medium dependent (PMD) entity <NUM>. The MAC sublayer <NUM> and the PHY layer <NUM> may respectively include management entities, which are respectively referred to as MAC sublayer management entities (MLME) <NUM>. These entities <NUM> and <NUM> provide a layer management service interface, for operation of a layer management function.

To provide accurate MAC operation, a station management entity (SME) <NUM> may be included in each STA. The SME <NUM> is a management entity independent of each layer, which is present in or off to one side of a separate management plane. Although the functions of the SME <NUM> are not accurately described in detail in this specification, such an entity <NUM> collects layer-dependent state information from several layer management entities (LMEs) and sets layer-specific parameter values. The SME <NUM> may perform such functions on behalf of general system management entities and implement standard management protocols.

The entities shown in <FIG> may interact using various methods. <FIG> shows an example of exchanging GET/SET primitives. request primitive is used to request a given management information base (MIB) attribute (management information based attribute information) value. confirm primitive is used to return an appropriate MIB attribute information value if a status is "SUCCESS" and to, otherwise, return error indication in a status field. request primitive is used to request setting of an indicated MIB attribute value to a given value. If the MIB attribute value indicates a specific operation, execution of the specific operation is requested. confirm primitive is used to confirm that the indicated MIB attribute is set to the requested value if a status is "SUCCESS" and to, otherwise, return an error condition in a status field. If the MIB attribute value indicates a specific opera-tion, this may indicate that the specific operation has been performed.

As shown in <FIG>, various MLME_GET/SET primitives may be exchanged between the MLME <NUM> and the SME <NUM> via an MLME_Service access point (SAP) <NUM>. Alternatively, various PLCM_GET/SET primitives may be exchanged between the PLME <NUM> and the SME <NUM> via a PLME_SAP <NUM> and may be exchanged between the MLME <NUM> and the PLME <NUM> via an MLME-PLME_SAP <NUM>.

The above-described embodiments of the present invention can be implemented by a variety of means, for example, hardware, firmware, software, or a combination thereof.

In the case of implementing the present invention by hardware, the present invention can be implemented with application specific integrated circuits (ASICs) , digital signal processors (DSPs) , digital signal processing devices (DSPDs) , programmable logic devices (PLDs) , field programmable gate arrays (FPGAs) , a processor, a controller, a microcontroller, a microprocessor, etc..

If operations or functions of the present invention are implemented by firmware or software, the present invention can be implemented in the form of a variety of formats, for example, modules, procedures, functions, etc. Software code may be stored in a memory unit so that it can be driven by a processor. The memory unit is located inside or outside of the processor, so that it can communicate with the aforementioned processor via a variety of well-known parts.

Both apparatus and method inventions are mentioned in this specification and descriptions of both of the apparatus and method inventions may be complementarily applicable to each other.

Claim 1:
A method for a non-access point station, non-AP STA, to communicate with an access point, AP, using orthogonal frequency divisional multiple access, OFDMA, or multi-user multiple input multiple output, MU-MIMO in a wireless local area network, WLAN, the method comprising:
receiving a physical protocol data unit, PPDU, from the AP, wherein the PPDU comprises a signaling, SIG, field including resource allocation information for a plurality of non-AP STAs and data field received through a frequency band based on the resource allocation information,
wherein the frequency band includes a plurality of resource units, the plurality of resource units including a normal resource unit allocated to one non-AP STA, and a multi-user resource unit which is a single resource unit allocated to more than one non-AP STA among the plurality of non AP STAs,
wherein the resource allocation information includes:
a common resource allocation information having a same bit sequence value for the plurality of non-AP STAs, and the same bit sequence value informing of a number of the plurality of resource units and various size of each of the plurality of resource units,
multi-user indication for a number of non-AP STAs, among the plurality of non-AP STAs, to which the multi-user resource unit is allocated, and
multiple ID fields for corresponding identification information of non-AP STA to which the normal resource unit or the multi-user resource unit is allocated.