Devices and methods for signalling unequal modulation transmission

Abstract

A wireless local area network, WLAN, station (110) is disclosed for single user, SU, or multi user, MU, communication with one or more further WLAN stations (120) via one or more spatial streams using an equal modulation, EQM, mode or an unequal modulation, UEQM, mode based on a plurality of modulation and coding schemes, MCSs, including 16 legacy MCSs and a plurality of additional MCSs. The WLAN station (110) is configured to send an EHT or UHR Physical Layer Protocol Data Unit, PPDU, including a preamble to the one or more further WLAN stations (120), wherein the preamble comprises one or more user fields, wherein each user field has a format in accordance with the IEEE 802.11be, IEEE 802.11bn or IEEE 802.11ax standard and wherein each user field is configured to encode the plurality of MCSs, i.e. the 16 legacy MCSs and the plurality of additional MCSs.

Description

[0001] DEVICES AND METHODS FOR SIGNALLING UNEQUAL MODULATION TRANSMISSION

[0002] TECHNICAL FIELD

[0003] The present invention relates to wireless communications. More specifically, the present invention relates to devices and methods for signalling unequal modulation transmission in a wireless local area network, WLAN, in particular a WLAN (also referred to as Wi-Fi network) according to the IEEE 802.11 framework of standards.

[0004] BACKGROUND

[0005] IEEE 802.11-based wireless local area networks, WLANs, (also referred to as Wi-Fi networks) have become popular at an unprecedented rate. According to the current IEEE 802.11 framework of standards, when multi-stream transmission is used, each spatial stream is modulated with the same modulation and coding scheme, MCS. In scenarios with a relatively high SNR difference between the streams, the MCS that corresponds to the stream with the lowest SNR is used for all the other streams. In these cases, streams that could use a high MCSs are compromised by having to use a lower MCS which degrades the overall throughput. For instance, a transmission with two spatial streams may be used, where one stream's SNR is, for instance, 20dB, while the other stream's SNR is, for instance, 3dB. When using equal modulation (herein also referred to as EQM) for both streams a robust MCS, e.g. QPSK 1 / 2, would be chosen to allow the detection also of the weaker stream. However, using such an MCS for the stronger stream would be significantly inefficient because the stronger stream could use a much higher MCS, e.g. 16 QAM 3 / 4, which could yield a 3 times higher rate. Thus, there is a need for signaling allowing for multi-stream transmission with unequal modulation (herein also referred to as UEQM) not supported by the current IEEE 802.11 framework of standards (up to the amendment IEEE 802.1 Ibe).

[0006] SUMMARY

[0007] It is an objective of the present disclosure to provide improved devices and methods for signalling unequal modulation (UEQM) transmission in a WLAN, in particular a WLAN according to the IEEE 802.11 framework of standards, i.e. a Wi-Fi network.

[0008] The foregoing and other objectives are achieved by the subject matter of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

[0009] According to a first aspect a wireless local area network, WLAN, station is provided for single user, SU, or multi user, MU, communication with one or more further WLAN stations via one or more spatial streams using an equal modulation, EQM, mode or an unequal modulation, UEQM, mode based on a plurality of modulation and coding schemes, MCSs, including 16 legacy MCSs, i.e. the 16 MCSs currently defined by the IEEE 802.11 framework of standards, and a plurality of additional MCSs.

[0010] The WLAN station according to the first aspect is configured to send an EHT or UHR Physical Layer Protocol Data Unit, PPDU, including a preamble to the one or more further WLAN stations, wherein the preamble comprises one or more user fields and wherein each user field has a format in accordance with the IEEE 802.11be, IEEE 802.11bn or IEEE 802.11ax standard. Each user field is configured to encode the plurality of MCSs, i.e. the 16 legacy MCSs and the plurality of additional MCSs. Thus, the WLAN station according to the first aspect provides the signaling for a transmission scheme which enables using a different modulation per spatial stream, so that each stream is transmitted with its appropriate modulation. This allows achieving a higher throughput when using multi-stream transmission when the MIMO channel condition causes a high difference of SNR between the streams. In a further possible implementation form, each user field in accordance with the IEEE 802.11be, IEEE 802.11bn or IEEE 802.1 lax standard comprises a STA ID subfield, an MCS subfield, a reserved bit subfield, anNSS subfield, a BFed subfield and a Coding subfield.

[0011] In a further possible implementation form, for each user field in accordance with the IEEE 802.1 Ibe, IEEE 802.1 Ibn or IEEE 802.1 lax standard the STA ID subfield has a size of 11 bits, the MCS subfield has a size of at least 4 bits, the reserved bit subfield has a size of 1 bit, the NSS subfield has a size of at least 4 bits, the BFed subfield has a size of 1 bit and the Coding subfield has a size of 1 bit.

[0012] In a further possible implementation form, a bit, in particular the MSB, of the NSS subfield of each user field indicates, i.e. encodes a first legacy encoding mode and a second encoding mode.

[0013] In a further possible implementation form, in the first legacy encoding mode the further bits, in particular the three LSBs, of the NSS subfield indicate, i.e. encode the number of spatial streams and the bits of the MCS subfield indicate one of the 16 legacy MCSs.

[0014] In a further possible implementation form, in the second encoding mode the further bits, in particular the three LSBs, of the NSS subfield indicate, i.e. encode the number of spatial streams and 2 bits of the MCS subfield (e.g. when the 2 MSB of the MCS subfield are set to 'll') indicate the EQM mode and 2 further bits of the MCS subfield (e.g. the 2 LSB) indicate one of the plurality of additional MCSs.

[0015] In a further possible implementation form, a bit combination of the 2 MSBs of the MCS subfield indicates the EQM mode (for instance, the bit combination 'll') and the 2 LSBs of the MCS subfield indicate one of the plurality of additional MCSs.

[0016] In a further possible implementation form, three bit combinations of the 2 MSBs of the MCS subfield (for instance, the three bit combinations 00, 01 and 10) indicate the UEQM mode and the 3 LSBs of the NSS subfield indicate, i.e. encode one of 8 sets, e.g. rows of modulation combinations, wherein each modulation combination defines the number of spatial streams and the pattern of modulation order differences used for the spatial streams and wherein the 4 bits of the MCS subfield indicate, i.e. encode for each of the 8 sets, e.g. rows of modulation combinations a specific modulation combination.

[0017] In a further possible implementation form, the 3 LSBs of the NSS subfield together with the 4 bits of the MCS subfield indicate, i.e. encode one of a plurality of modulation combinations, wherein each modulation combination defines the number of spatial streams and the MCS used for each spatial stream.

[0018] In a further possible implementation form, the reserved bit subfield of each user field indicates the EQM mode or the UEQM mode.

[0019] In a further possible implementation form, for the EQM mode 3 bits, in particular the 3 LSBs, of the NSS subfield indicate, i.e. encode the number of spatial streams and the 4 bits of the MCS subfield together with the remaining bit, in particular the MSB, of the NSS subfield indicate, i.e. encode one of the plurality of MCSs.

[0020] In a further possible implementation form, a bit, in particular the MSB, of the NSS subfield of each user field indicates a first legacy encoding mode and a second encoding mode. In a further possible implementation form, in the first legacy encoding mode the 3 further bits, in particular the three LSBs, of the NSS subfield indicate, i.e. encode the number of spatial streams and the 4 bits of the MCS subfield indicate, i.e. encode one of the 16 legacy MCSs.

[0021] In a further possible implementation form, in the second encoding mode the 3 further bits, in particular the three LSBs, of the NSS subfield indicate, i.e. encode the number of spatial streams and 2 or more bits of the MCS subfield indicate one of the plurality of additional MCSs.

[0022] In a further possible implementation form, for the UEQM mode 3 bits, in particular the 3 LSBs, of the MCS subfield indicate, i.e. encode one of 8 sets, e.g. rows of modulation combinations, wherein each modulation combination defines the number of spatial streams and the pattern of modulation order differences used for the spatial streams and wherein the 4 bits of the NSS subfield indicate, i.e. encode for each of the 8 sets, e.g. rows of modulation combinations a specific modulation combination.

[0023] In a further possible implementation form, for the UEQM mode 3 bits, in particular the 3 LSBs, of the NSS subfield indicate, i.e. encode one of 8 sets, e.g. rows of modulation combinations, wherein each modulation combination defines the number of spatial streams and the pattern of modulation order differences used for the spatial streams and wherein the 4 bits of the MCS subfield indicate, i.e. encode for each of the 8 sets, e.g. rows of modulation combinations a specific modulation combination.

[0024] In a further possible implementation form, for the UEQM mode the 4 bits of the MCS subfield together with at least 3 bits, in particular the 3 LSBs, of the NSS subfield indicate, i.e. encode a plurality of modulation combinations, wherein each modulation combination defines the number of spatial streams and the pattern of modulation order differences used for these spatial streams.

[0025] In a further possible implementation form, for the UEQM mode the 4 bits of the NSS subfield indicate, i.e. encode the MCS of a first spatial stream of the one or more spatial streams and at least 3 bits, in particular the 3 LSBs (provided 3 bits are sufficient), of the MCS subfield indicate, i.e. encode one of 8 sets, e.g. rows of modulation combinations, wherein each modulation combination defines the number of spatial streams and the pattern of modulation order differences used for these spatial streams.

[0026] In a further possible implementation form, for the UEQM mode the 4 bits of the MCS subfield indicate, i.e. encode the MCS of a first spatial stream of the one or more spatial streams and at least 3 bits, in particular the 3 LSBs (provided 3 bits are sufficient), of the NSS subfield indicate, i.e. encode one of 8 sets, e.g. rows of modulation combinations, wherein each modulation combination defines the number of spatial streams and the pattern of modulation order differences used for these spatial streams.

[0027] In a further possible implementation form, the reserved bit of each user field indicates a first legacy encoding mode and a second encoding mode.

[0028] In a further possible implementation form, in the first legacy encoding mode at least 3 bits, in particular the three LSBs, of the NSS subfield indicate, i.e. encode the number of spatial streams and the 4 bits of the MCS subfield indicate, i.e. encode one of the 16 legacy MCSs.

[0029] In a further possible implementation form, in the second encoding mode at least 3 bits, in particular the three LSBs, of the NSS subfield indicate, i.e. encode the number of spatial streams and 2 bits of the MCS subfield (e.g. setting the 2 MSB to 'l l') indicate the UEQM mode and 2 further bits of the MCS subfield (e.g. the 2 LSB) indicate one of the plurality of additional MCSs. In a further possible implementation form, each user field in accordance with the IEEE 802.1 Ibe, IEEE 802.11 bn or IEEE 802.1 lax standard comprises a STA ID subfield of 11 bits, a MCS subfield of 4 bits, a Coding subfield of 1 bit, and a Spatial Configuration subfield of 6 bits.

[0030] In a further possible implementation form, 4 bits, in particular the 4 LSB, of the Spatial Configuration subfield of each user field indicate the number of spatial streams per station and the 4 bits of the MCS subfield together with the other 2 bits, in particular the 2 MSBs, of the Spatial Configuration subfield indicate a plurality of modulation combinations, wherein a first subset of the plurality of modulation combinations defines for the EQM mode up to 20 MCSs and a second subset of the plurality of modulation combinations defines for the UEQM mode the number of spatial streams and the MCS for each spatial stream.

[0031] In a further possible implementation form, for the UEQM mode 4 bits of the MCS subfield indicate, i.e. encode one of 9 sets, e.g. rows of modulation combinations, wherein each modulation combination defines the number of spatial streams and the pattern of modulation order differences used for these spatial streams and wherein the 4 bits of the NSS subfield indicate, i.e. encode for each of the 9 sets, e.g. rows of modulation combinations a specific modulation combination.

[0032] In a further possible implementation form, for the UEQM mode 4 bits of the NSS subfield indicate, i.e. encode one of 9 sets, e.g. rows of modulation combinations, wherein each modulation combination defines the number of spatial streams and the pattern of modulation order differences used for these spatial streams and wherein the 4 bits of the MCS subfield indicate, i.e. encode for each of the 9 sets, e.g. rows of modulation combinations a specific modulation combination.

[0033] In a further possible implementation form, for the UEQM mode the 4 bits of the MCS subfield together with at least 3 bits, in particular the 3 LSBs, of the NSS subfield indicate, i.e. encode a plurality of modulation combinations, wherein each modulation combination defines the number of spatial streams and the pattern of modulation order differences used for these spatial streams.

[0034] In a further possible implementation form, for the UEQM mode the 4 bits of the NSS subfield indicate, i.e. encode the MCS of a first spatial stream of the one or more spatial streams and 4 bits, in particular the 4 LSBs, of the MCS subfield indicate, i.e. encode one of 9 sets, e.g. rows of modulation combinations, wherein each modulation combination defines the number of spatial streams and the pattern of modulation order differences used for these spatial streams.

[0035] In a further possible implementation form, for the UEQM mode the 4 bits of the MCS subfield indicate, i.e. encode the MCS of a first spatial stream of the one or more spatial streams and 4 bits, in particular the 4 LSBs, of the NSS subfield indicate, i.e. encode one of 9 sets, e.g. rows of modulation combinations, wherein each modulation combination defines the number of spatial streams and the pattern of modulation order differences used for these spatial streams.

[0036] In a further possible implementation form, each user field comprises a STA ID subfield of 11 bits, a MCS / UEQM subfield of at least 6 bits, a Coding subfield of 1 bit, and a Spatial Configuration subfield of at least 4 bits, wherein the MCS / UEQM subfield is configured to encode the plurality of MCSs, i.e. the 16 legacy MCSs and the plurality of additional MCSs, and wherein the at least 6 bits of the MCS / UEQM subfield and the at least 4 bits of the Spatial Configuration subfield encode the plurality of MCSs, i.e. the 16 legacy MCSs and the plurality of additional MCSs.

[0037] In a further possible implementation form, each user field in accordance with the IEEE 802.1 Ibe, IEEE 802.11 bn or IEEE 802.1 lax standard comprises a STA ID subfield of 11 bits, a MCS subfield of 4 bits, a Coding subfield of 1 bit, and a Spatial Configuration subfield of 6 bits. According to a second aspect a method is provided for operating a wireless local area network, WLAN, station for single user, SU, or multi user, MU, communication with one or more further WLAN stations via one or more spatial streams using an equal modulation, EQM, mode or an unequal modulation, UEQM, mode based on a plurality of modulation and coding schemes, MCSs, including 16 legacy MCSs and a plurality of additional MCSs. The method according to the second aspect comprises sending an EHT or UHR Physical Layer Protocol Data Unit, PPDU, including a preamble to the one or more further WLAN stations, wherein the preamble comprises one or more user fields, wherein each user field has a format in accordance with the IEEE 802.11 be, IEEE 802.11 bn or IEEE 802.11 ax standard and wherein each user field is configured to encode the plurality of MCSs, i.e. the 16 legacy MCSs and the plurality of additional MCSs.

[0038] The method according to the second aspect can be performed by the WLAN station according to the first aspect. Thus, further features of the method according to the second aspect result directly from the functionality of the WLAN station according to the first aspect as well as its different implementation forms described above and below.

[0039] According to a third aspect a computer program product is provided, comprising program code which causes a computer or a processor to perform the method according to the second aspect, when the program code is executed by the computer or the processor.

[0040] Details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description, drawings, and claims.

[0041] BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In the following, embodiments of the present disclosure are described in more detail with reference to the attached figures and drawings, in which:

[0043] Fig. 1 shows a schematic diagram illustrating a WLAN station according to an embodiment in the form of an AP in communication with a plurality of further WLAN stations according to an embodiment in form of a plurality of non-AP stations;

[0044] Fig. 2 shows a diagram of an EHT user field of a non-MU MIMO frame transmitted by a WLAN station according to an embodiment and a diagram of an EHT user field of a MU MIMO frame transmitted by a WLAN station according to a further embodiment;

[0045] Fig. 3a shows a table for spatial configuration subfield encoding;

[0046] Fig. 3b shows a table including a plurality of modulation and coding schemes, MCSs, including 16 legacy MCSs and 4 additional MCSs, encodable by a WLAN station according to an embodiment;

[0047] Fig. 3c shows a table including a plurality of MCS combinations for UEQM with two spatial streams encodable by a WLAN station according to an embodiment;

[0048] Fig. 3d shows a table including a plurality of MCS combinations for UEQM with several spatial streams encodable by a WLAN station according to an embodiment;

[0049] Figs. 3e-g show tables illustrating the number of QAM combinations for two, three, and four spatial streams, respectively; Fig. 4 shows a diagram of a user field of a non-MU MIMO frame transmited by a WLAN station according to an embodiment for signaling EQM with a new MCS;

[0050] Fig. 5 shows a diagram of a user field of a non-MU MIMO frame transmited by a WLAN station according to an embodiment for signaling UEQM with three MCSs;

[0051] Fig. 6 shows a diagram of a user field of a SU MIMO frame transmited by a WLAN station according to an embodiment;

[0052] Fig. 7 shows a diagram of a user field of a SU MIMO frame transmitted by a WLAN station according to an embodiment for signaling EQM with a legacy MCS;

[0053] Fig. 8 shows a diagram of a user field of a SU MIMO frame transmitted by a WLAN station according to an embodiment for signaling EQM with a new MCS;

[0054] Fig. 9 shows a diagram of a user field of a SU MIMO frame transmitted by a WLAN station according to an embodiment for signaling UEQM with three spatial streams;

[0055] Fig. 10 shows a diagram of a user field of a SU MIMO frame transmited by a WLAN station according to a further embodiment for signaling UEQM with three spatial streams;

[0056] Fig. 11 shows a diagram of a user field of a SU MIMO frame transmited by a WLAN station according to an embodiment for signaling UEQM with three spatial streams and indicating the first spatial stream;

[0057] Fig. 12 shows a diagram of a user field of a SU MIMO frame transmited by a WLAN station according to a further embodiment for signaling UEQM with three spatial streams and indicating the first spatial stream;

[0058] Fig. 13 shows a merged EQM and UEQM table implemented by a WLAN station according to an embodiment;

[0059] Fig. 14 shows a table including a plurality of MCS combinations for UEQM with several spatial streams encodable by a WLAN station according to an embodiment;

[0060] Fig. 15 shows a diagram of a user field of a SU MIMO frame transmited by a WLAN station according to an embodiment for signaling UEQM with four spatial streams;

[0061] Fig. 16 shows a diagram of a user field of a SU MIMO frame transmited by a WLAN station according to a further embodiment for signaling UEQM with four spatial streams;

[0062] Fig. 17 shows a diagram of a user field of a SU MIMO frame transmited by a WLAN station according to an embodiment for signaling UEQM with two spatial streams and indicating the first spatial stream;

[0063] Fig . 18 shows a diagram of a user field of a SU MIMO frame transmited by a WLAN station according to a further embodiment for signaling UEQM with two spatial streams and indicating the first spatial stream;

[0064] Fig. 19 shows a merged EQM and UEQM table implemented by a WLAN station according to an embodiment for four spatial streams; Fig. 20 shows a diagram of a user field of a MU MEMO frame with a unified MCS / UEQM field transmitted by a WLAN station according to a further embodiment for signaling UEQM; and

[0065] Fig. 21 shows a flow diagram illustrating a method of operating a WLAN station according to an embodiment.

[0066] In the following, identical reference signs refer to identical or at least functionally equivalent features.

[0067] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0068] In the following description, reference is made to the accompanying figures, which form part of the disclosure, and which show, by way of illustration, specific aspects of embodiments of the present disclosure or specific aspects in which embodiments of the present disclosure may be used. It is understood that embodiments of the present disclosure may be used in other aspects and comprise structural or logical changes not depicted in the figures. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

[0069] For instance, it is to be understood that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if one or a plurality of specific method steps are described, a corresponding device may include one or a plurality of units, e.g. functional units, to perform the described one or plurality of method steps (e.g. one unit performing the one or plurality of steps, or a plurality of units each performing one or more of the plurality of steps), even if such one or more units are not explicitly described or illustrated in the figures. On the other hand, for example, if a specific apparatus is described based on one or a plurality of units, e.g. functional units, a corresponding method may include one step to perform the functionality of the one or plurality of units (e.g. one step performing the functionality of the one or plurality of units, or a plurality of steps each performing the functionality of one or more of the plurality of units), even if such one or plurality of steps are not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary embodiments and / or aspects described herein may be combined with each other, unless specifically noted otherwise.

[0070] Figure 1 shows a wireless communication network 100, in particular a wireless local area network, WLAN, in accordance with the IEEE 802.11 framework of standards (also referred to as a Wi-Fi network 100). The WLAN or Wi-Fi network 100 comprises a WLAN station 110 (also referred to as Wi-Fi station 110 herein), which may be implemented in the form of an AP 110, and a plurality of further WLAN stations 120 (also referred to as further Wi-Fi stations 120 herein) in the form of, for instance, non-AP stations 120. As illustrated in figure 1, by way of example, the non-AP stations 120 may comprise smartphones, laptop computers, tablet computers, desktop computers or other types of wireless devices 120. In the following several embodiments of the AP 110 as WLAN transmitter station 110 and the non-AP stations 120 as WLAN receiver stations 120 will be described in more detail below. As will be appreciated, however, the non-AP stations 120 may be implemented to have the same functionality as the AP 110 described in more detail further below.

[0071] As further illustrated in figure 1, the AP 110 may comprise a processing circuitry 111 and a communication interface 113, in particular a wireless communication interface 113 enabling communication in accordance with the IEEE 802.11 framework of standards over a channel 130. The processing circuitry 111 may be implemented in hardware and / or software and may comprise digital circuitry, or both analog and digital circuitry. Digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), or general-purpose processors. The AP 110 may further comprise a memory 115 configured to store executable program code which, when executed by the processing circuitry 111, causes the AP 110 to perform the functions and methods described herein. Likewise, as indicated in figure 1, the non-AP station(s) 120 may comprise a processing circuitry 121 and a communication interface 123, in particular a wireless communication interface 123 enabling a communication in accordance with the IEEE 802.11 framework of standards over the channel 130. The processing circuitry 121 may be implemented in hardware and / or software and may comprise digital circuitry, or both analog and digital circuitry. Digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), or general-purpose processors. The non-AP station(s) 120 may further comprise a memory 125 configured to store executable program code which, when executed by the processing circuitry 121, causes the non-AP station(s) 120 to perform the functions and methods described herein.

[0072] Before describing detailed embodiments of the WLAN station 110 implemented, for instance, as the AP 110 of figure 1 and the further WLAN station(s) implemented, for instance, as the non-AP station(s) 120 of figure 1 , in the following some technical background as well as terminology will be introduced making use of one or more of the following abbreviations and / or acronyms:

[0073] AP Access Point

[0074] AWGN Additive White Gaussian Noise

[0075] BCC Binary Convolutional Code

[0076] BPSK Binary Phase Shift Keying

[0077] BW Bandwidth

[0078] CFO Carrier Frequency Offset

[0079] DCM Dual-Carrier Modulation

[0080] EQM Equal Modulation

[0081] IEEE Institute of Electrical and Electronics Engineers

[0082] LDPC Low Density Parity Check

[0083] LTF Long Training Field

[0084] MCS Modulation and Coding Scheme (Rate)

[0085] MIMO Multiple Input Multiple Output

[0086] MU-MIMO Multi-User MIMO

[0087] OFDM / A Orthogonal Frequency Division Multiplexing / Multiple-Access

[0088] PER Packet Error Rate

[0089] PPDU PHY (Physical Layer) Protocol Data Unit

[0090] PSD Power Spectral Density

[0091] QAM Quadrature Amplitude Modulation

[0092] RU Resource Unit

[0093] SNR Signal to Noise Ratio

[0094] STA: Station, may be an AP STA or a non-AP STA

[0095] STF Short Training Field

[0096] TB Trigger Based

[0097] UHR Ultra High Reliability

[0098] UEQM Unequal Modulation

[0099] U-SIG Universal SIG (a signal field defined in IEEE 802.1 Ibe)

[0100] According to the current IEEE 802.11 framework of standards there are two types of multi stream transmission, namely non- MU-MIMO (also referred to as single user, SU, MIMO) and MU-MIMO. In non-MU-MIMO multiple spatial streams are transmitted to the same WLAN receiver station. In MU-MIMO multiple spatial streams are transmitted to multiple WLAN receiver stations over the same resources in the DL or multiple spatial streams are transmitted from multiple WLAN transmitter stations to a single WLAN receiver stations over the same resources in the UL.

[0101] According to IEEE 802.11 be (and similarly IEEE 802.11 ax) the signaling of multi-stream transmission exists mainly in the user fields of the EHT-SIG field (referred to as HE SIG-B field in IEEE 802.1 lax) in non-TB transmission and in the user-field of the trigger-frame in a TB transmission. This user-specific field consist of several user fields in which the parameters of each WLAN receiver station are defined. Figure 2 shows a diagram of an EHT user field 200 for non-MU MIMO transmission by the WLAN station 110 according to an embodiment and a diagram of an EHT user field 300 for MU MIMO frame transmission by the WLAN station 110 according to an embodiment. As can be taken from figure 2, the standard non-MU-MIMO user field 200 comprises a STA ID subfield 210 with a size of 11 bits, an MCS subfield 220 with a size of 4 bits, a reserved bit subfield 230 with a size of 1 bit, an NSS subfield 240 with a size of 4 bits, a BFed subfield 250 with a size of 1 bit and a Coding subfield 260 with a size of 1 bit. According to the current IEEE 802.11 framework of standards the user field 200, for instance, of an EHT-SIG field indicates the MCS (4 bits) and the number of streams (using a total of 22 bits, on top of which 4 bits CRC and 6 tail bits are later added). The standard MU-MIMO user field 300 illustrated in figure 2 comprises a STA ID subfield 310 of 11 bits, an MCS subfield 320 of 4 bits, a Coding subfield 330 of 1 bit, and a Spatial Configuration subfield 340 of 6 bits. As will be described in great detail in the following, the WLAN station 110 is configured to use user field(s) 200, the user field(s) 300 or variants thereof for signaling UEQM transmission.

[0102] According to the current IEEE 802.11 framework of standards there are 16 valid MCS values (herein also referred to as legacy MCS), namely 14 values for BPSK rate ‘ / 2up to 4K-QAM rate 5 / 6, BPSK+DCM and BPSK+DCM+DUP. MCS 14 (BPSK+DCM+DUP) is limited to a single spatial stream. This means that the other 15 legacy MCS values may be used for transmission with multiple spatial streams. Though 4 bits are defined for the NSS subfield 240, up to 8 spatial streams can be signaled via this sub-field (valid values are 0-7). In the non-MU-MIMO case, the reserved bit is set to ‘1’. With equal modulation and 2 spatial streams, there is a total of 16+14 = 30 options.

[0103] In the case of MU-MIMO, according to the current IEEE 802.11 framework of standards the Spatial Configuration subfield 300 indicates (via 6 bits) how many streams are allocated per station (up to 8 STAs, 1 stream each). Most of the field values are reserved (unused), as illustrated in the table shown in figure 3a, which shows the number of reserved entries for the exemplary case of 2 spatial streams. For example, in the case of 2 stations only 10 out of 64 entries are used, and in the case of 3 stations only 13 out of 64 are used. As will be appreciated from figure 3a, for MU-MIMO there are many reserved entries in the Spatial Configuration subfield 300 that are unused.

[0104] Unequal Modulation has been considered for TGbn (802.1 Ibn) and there have been suggestions to add additional MCSs (values) to the existing legacy MSCs. For instance, figure 3b shows a table (referred to herein as table 2) including in addition to the 15 legacy MCSs for multi-stream transmission 4 new MCS values (shown in light grey), namely MCS 1.1, MCS3.1, MCS4.2, and MCS7.2. As will be appreciated, the 4 additional MCS values illustrated in table 2 shown in figure 3b lead to a difference of up to 2 modulation orders between the strongest and weakest MCS (for 2-4 streams). This, leads to the 24 possible options, i.e. stream combinations for 2 streams illustrated in table 1 shown in figure 3c.

[0105] There has been a further suggestion to support the modulation differences, i.e. combinations of modulations illustrated in table 3 shown in figure 3d. For example, for 2 / 3 / 4 spatial streams BPSK may only be transmitted along with QPSK or 16QAM. Table 4 shown in figure 3e, table 5 shown in figure 3f, and table 6 shown in figure 3g summarize the number of possible QAM combinations supported for table 3 for two, three, and four spatial streams, respectively. As can be taken from tables 4, 5 and 6, there are a total of 8 rows (2+3+3), while the total number of combinations is 24+34+34=92. As will be appreciated, for EQM with up to 8 streams there are 8*19+1=153 possible combinations (19 modulations that are valid for multi-stream and 1 modulation - MCS14 that is valid for a single stream).

[0106] As will be described in more detail in the following, the WLAN station 110 of figure 1 is configured for single user, SU, or multi user, MU, communication with the one or more further WLAN stations 120 via one or more spatial streams using an equal modulation, EQM, mode or an unequal modulation, UEQM, mode based on a plurality of MCSs, including 16 legacy MCSs and a plurality of additional, i.e. new MCSs (not currently defined in the IEEE 802.11 framework of standards). For signaling this transmission the WLAN station 110 is configured to send an EHL or UHR Physical Layer Protocol Data Unit, PPDU, including a preamble to the one or more further WLAN stations 120, wherein the preamble comprises for each user the user field 200 illustrated in figure 2, the user field 300 illustrated in figure 2 or the user field 400 illustrated in figure 20. As will be described in more detail in the following, each user field 200, 300, 400 has a format in accordance with the IEEE 802.11be, IEEE 802.11bn or IEEE 802.11ax standard and is configured to encode the plurality of MCSs, i.e. the 16 legacy MCSs and the plurality of additional, i.e. new MCSs (not currently defined in the IEEE 802.11 framework of standards). Thus, embodiments disclosed herein provide signaling solutions that do not require adding bits to the currently standardized user specific field. Moreover, embodiments disclosed herein support a plurality of different combinations and / or MCS values for both SU-MIMO and MU-MIMO.

[0107] The following UEQM tables 7, 8, 9, 10, 11, 12, 13, and 14 define the combination signaling for each combination of number of spatial streams and (unequal) modulations values implemented by the WLAN station 110 according to an embodiment. In the following tables 7 to 14 as well as the tables 3 to 6 already described above, the following notation is used: M denotes the index value, i.e. order of a first MCS, M-l denotes the index value, i.e. order of a second MCS having an index value smaller by one than the first MCS, and M-2 denotes the index value, i.e. order of a third MCS having an index value smaller by two than the first MCS. The notation {M, M-l, M-2} (herein also referred to as pattern of modulation order differences) indicates a combination of the first MCS with the modulation index M, the second MCS with the modulation index M-l, and the third MCS with the modulation index M-2. Another notation {M, M, M-l} indicates a combination of the first and second MCSs with the modulation index M and a third MCS with the modulation index M-l . According to embodiments disclosed herein, the WLAN station 110 according to an embodiment is configured to signal these kinds of modulation combinations or patterns of modulation order differences.

[0108]

[0109] Table 8: 2 streams: {M, M-2} - 001 in Table 3 / 0001 in Table 20 Table 11: 3 streams {M, M-l, M-2} - 100 in Table 3 / 0100 in Table 20

[0110] Table 12: 4 streams {M, M, M, M-l} - 101 in Table 3 / 0101 in Table 20

[0111] Table 13: 4 streams {M, M, M, M-2} - 110 in Table 3 / 1000 in Table 20 Table 14: 4 streams {M, M, M-l, M-2} - 111 in Table 3 / 0111 in Table 20

[0112] According to an embodiment illustrated in figure 4, for SU-MIMO the MSB of the NSS sub-field 240 of each user field 200 indicates if using existing (16 legacy) MCS values (e.g. value ‘0’) or additional MCS values (e.g. 3 NSS LSBs indicate number of streams and 4 MCS bits indicate existing MCS (as defined framework of standards). If MSB = ‘1’, then for EQM of 16 valid MCS values, the last 4 indic MCS values as defined in Table 16 - New MCS values. This means that the 4 newMCSs are s MCS sub-field 220 provided that the 2 MSB are T 1 ' . The number of streams is defined by 3 NS the exemplary user field 200 shown in figure 4 signals two spatial streams, each with 16QAM% (i.e. EQM with a new MCS). A variant of the embodiment shown in figure 4 is shown in figure 5 for UEQM. Of the 16 MCS values, the first 12 indicate UEQM, where 3 NSS LSBs indicate one of 8 (2+3+3) rows of modulation combinations, and the 12 values indicate which of the specific modulation combinations is used (here 2 combinations may be discarded in some cases, such as BPSK+QPSK). By way of example, the exemplary user field 200 shown in figure 5 signals UEQM with 3 spatial streams based on Table 9 above: 64QAM %, 64QAM%, 16QAM %. According to a further embodiment, the WLAN station 110 and the further WLAN stations 120 may make use of the following table 15 that does not require discarding any UEQM combination.

[0113]

[0114] Table 15: UEQM for two, three and four spatial streams

[0115] According to a further embodiment, the value of the reserved bit 230 of the user field 200 being, for instance, ‘0’ may indicate UEQM, while a value of, for instance, ‘1’ may indicate EQM. In case of EQM according to a first variant illustrated in figure 6 the 3 LSBs of the NSS subfield 240 may signal the number of streams, while the 4 bits of the MCS subfield 220 together with the MSB of the NSS subfield 240 (i.e. 5 bits in total) signal the MCS.

[0116] According to a variant of the embodiment shown in figure 6, if the MSB of the NSS subfield 240 is ‘O’, then the 4 MCS bits indicate one of the 16 legacy MCS values. If the MSB of the NSS subfield 240 is ‘ 1’ , then the 2 MCS MSBs (or 2 LSBs) may indicate the additional, i.e. new MCS values (possibly 3 MSBs if more values are needed). For the case of 4 additional, i.e. new MCSs, as illustrated in table 2 of figure 3b, the signaling implemented by the WLAN station 110 according to an embodiment may be based on the following table 16:

[0117] Table 16: New MCS values

[0118] Figure 7 shows an exemplary user field 200 generated by the WLAN station 110 according to an embodiment for signaling a legacy MCS QPSK 3 / 4 with 2 spatial streams, while figure 8 shows an exemplary user field 200 generated by the WLAN station 110 according to an embodiment for signaling a new MCS 256QAM % with 2 spatial streams.

[0119] As will be appreciated, for the case of UEQM according to embodiments one of at least 92 options, i.e. possible combinations may have to be signaled. Therefore, according to an embodiment the WLAN station 110 is configured to use 3 MCS LSBs to indicate 1 of 8 rows (2 / 3 / 4 streams with all options) listed in Table 3 shown in figure 3d (000, 001 , ... I l l) and correspond to one of the UEQM tables, i.e. tables 7-14 described above. In other words, the content of the chosen row of Table 3 serves as the pointer to one of the tables 7-14, for example a content of 000 points to the first table, i.e. Table 7, a content of 001 points to the second table, i.e. Table 8 and so on until a content of 111 that points to the 8thtable, i.e. Table 14. Moreover, the WLAN station 110 is configured to use 4 NSS bits to indicate one of (up to) 16 modulation combinations which correspond to the row of the chosen UEQM table, i.e. one of up to (theoretical) 16 tables. As will be appreciated, this allows signaling up to 256 options, i.e. possible combinations using all 8 bits, namely 4 bits for up to 16 rows of 2 / 3 / 4 stream table, and 4 bits for up to 16 modulation combination options. An exemplary user field 200 for this embodiment is shown in figure 9. More specifically, the exemplary user field 200 of figure 9 is for a SU-MIMO allocation for transmitting 3 spatial streams to the further WLAN station 120, where the MCSs of the respective spatial streams are 16QAM %, 16QAM %, QPSK % (corresponding to the sixth row of Table 9 described above). Moreover, using different MCS values than 16QAM %, 16QAM %, QPSK % that still comply with the pattern {M, M, M-l } would require referring to a different row in table 9 described above, for example using the MCS values 16QAM %, 16QAM %, QPSK % would require using the 3rdrow of Table 9. As will be appreciated, using a different MCS pattern other than those defined in Table 3 would require referring to a different table than tables 7 to 14 described above.

[0120] According to a variant of the previous embodiment, the role of the bits of the MCS subfield 220 and the role of the bits of the NSS subfield 240 may be exchanged, as illustrated by the example in figure 10, which is for a SU-MIMO allocation for transmitting 3 spatial streams to the further WLAN station 120, where the MCSs of the respective spatial streams are 16QAM %, 16QAM3 / 4, QPSK3 / 4.

[0121] According to a further embodiment, for UEQM a table containing all possible combinations, such as 92 possible combinations may be generated and used by the WLAN station 110 for using 7 bits (4 MCS, 3 NSS LSBs) or all 8 bits to indicate a specific combination.

[0122] According to a further embodiment, the WLAN station 110 may be configured to signal the MCS of the first stream and a UEQM structure or pattern that allows to derive the MCS of any further spatial streams based on the MCS of the first stream. The following UEQM-MCS table 17 contains all the MCSs that are valid for the first stream and their signaling value.

[0123] Table 17: UEQM valid MCS for the 1st stream

[0124] As will be appreciated, BPSK A, QPSK %, QPSK3A and 16QAM % are omitted from table 17, because according to some scenarios these MCSs may never be the first MCS in an UEQM setting.

[0125] According to an embodiment, the WLAN station 110 is configured to use 3 MCS LSBs to indicate 1 of 8 rows (2 / 3 / 4 streams with all options) described in Table 3 of figure 3d (000, 001, ... I l l) and correspond to one of the UEQM tables described above (similar to a previously described embodiment). Moreover, the WLAN station 110 may use the 4 NSS bits to indicate the modulation of the first stream based on Table 17. An exemplary user field 200 for this embodiment is shown in figure 11.

[0126] According to a variant of the previous embodiment, the role of the bits of the MCS subfield 220 and the role of the bits of the NSS subfield 240 may be exchanged, as illustrated by the example in figure 12.

[0127] According to a further embodiment, the reserved bit 230 may be used instead of the MSB of the NSS subfield 240 to indicate if one of the legacy MCS values (e.g. value ‘0’) or an additional MCS value (e.g. value ‘1’) is used. The MSB of the NSS subfield 240 may be kept zero as long as no more than 8 spatial streams are supported.

[0128] In the following some embodiments of the WLAN station 110 for MU-MIMO transmission are described in more detail. According to an embodiment, in order to refrain from adding bits to the currently standardized user fields 300, the reserved fields in the spatial configuration sub-field 340 may be used. Each further WLAN station 120 may decode its own indication (i.e. it does not care about UEQM of other STAs). Since for the scenario used for tables 1 and 2 there are at most 34 options per 3 or 4 streams, no more than 34 values are required to indicate modulation per stream (per STA) in the MU-MIMO UEQM case.

[0129] Thus, according to an embodiment, the WLAN station 110 is configured to use, for instance, the 4 Spatial Configuration LSBs to indicate per-STA number of streams (like today) and to use the 4 MCS bits together with, for instance, 2 Spatial Configuration MSBs to indicate one of (up to) 64 options. The first 20 options may correspond to EQM with up to 20 MCS values, while the next 34 (or more) options correspond to UEQM corresponding to the tables per N_SS (from Spatial Configuration table). Table 18 shown in figure 13 depicts an example for the EQM+UEQM options that may be implemented by the WLAN station 110 according to an embodiment.

[0130] According to a further embodiment, the WLAN station 110 may be configured in the following way for signaling SU-MIMO UEQM transmission. The WLAN station 110 may be configured to set the reserved bit 230, for instance, to the value ‘0’ for indicating UEQM, otherwise a value ‘1’ of the reserved bit 230 indicates EQM. In case of UEQM the WLAN station 110 may use the table 19 illustrated in figure 14 and the following table 20 that adds to Table 7 to Table 14 to describe and indicate all 9 modulations combinations.

[0131] Table 20: 4 streams {M, M-l, M-l, M-2} - 0110 in Table 19 According to a variant, the WLAN station 110 is configured to use the 4 MCS bits for indicating 1 of 9 rows (2 / 3 / 4 streams with all options) of Table 19 of figure 14 (0000, 0001, ... 0111, 1000) corresponding to one of the UEQM tables, i.e. tables 7 to 14 and table 20 described above. Moreover, the WLAN station 110 may use the 4 NSS bits to indicate one of (up to) 16 modulation combinations which correspond to the row of the chosen UEQM table, i.e. tables 7 to 14 or table 20 described above. As will be appreciated, this allows to indicate up to 256 options in total (using all 8 bits), namely 4 bits for up to 16 rows of the 2 / 3 / 4 stream table, and 4 bits for up to 16 modulation combination options. An exemplary user field 200 for this embodiment is shown in figure 15, i.e. a user field 200 for a SU-MIMO allocation for transmitting 4 spatial streams to the further WLAN station 120 where the streams' MCSs are 64QAM %, 16QAM %, 16QAM %, QPSK % (corresponding to the 4th row of Table 20 described above).

[0132] According to a variant of the previous embodiment, the role of the bits of the MCS subfield 220 and the role of the bits of the NSS subfield 240 may be exchanged, as illustrated by the example in figure 16.

[0133] According to a further embodiment, for UEQM signaling the WLAN station 110 may be configured to use a table containing all combinations (such as 102 UEQM combinations), and to use 7 bits (4 MCS, 3 NSS LSBs) or all 8 bits to indicate a specific combination.

[0134] An alternative table may contain all UEQM and EQM combinations according to the following scheme. For EQM 19 MCSs with 1-8 streams + 1 MCS 14 supporting a single stream only for a total 19*8+1 = 153 combinations. For UEQM, as illustrated in table 19, there are 3 patterns with M and M-l only (i.e. no M-2)that correspond to the 1st, 3rdand 6throws in Table 19, each represents 14 modulations combinations = total of 42 combinations (for example, the modulation pattern M, M-l represents the modulations combinations MCS1, MCS0; MCS3,MCS1; MCS3.1,MCS1.1; MCS5, MCS3.1; MCS7.2, MCS5; MCS12, MCS10; MCS10, MCS8; MCS8, MCS6; MCS6, MCS4; MCS4, MCS2; MCS13, MCS11; MCS11, MCS9; MCS9, MCS7; MCS7, MCS4.2 )The other 6 patterns (other rows in Table 19) contain both M and M-2for example M, M-l, M-2 in the 5throw, therefore each pattern represents 10 modulations combinations = total of 60 combinations. Thus, the total number of combinations is 153+42+60 = 255.

[0135] According to a further variant of this embodiment (similar to some of the other embodiments described above), the WLAN station 110 may be configured to signal the MCS of the first stream and a UEQM structure or pattern that allows to derive the MCS of any further spatial streams based on the MCS of the first stream.

[0136] According to a further embodiment (an example of which is shown in figure 17) the WLAN station 110 may be configured to use the MCS bits to indicate 1 of 9 rows (2 / 3 / 4 streams with all options) described in table 3 of figure 3d (0000, 0001, ... 0111, 1000) and corresponding to one of the UEQM tables described above. Moreover, the WLAN station 110 may be configured to use the 4 NSS bits to indicate the modulation of the first stream based on Table 17 described above. As already indicated, an exemplary user field 200 for this embodiment is shown in figure 17.

[0137] According to a variant of the previous embodiment, the role of the bits of the MCS subfield 220 and the role of the bits of the NSS subfield 240 may be exchanged, as illustrated by the example in figure 18.

[0138] According to an embodiment for MU-MIMO transmission signaling the WLAN station 110 may be configured to support, i.e. make use of the additional pattern {M, M-l, M-l, M-2} defined in table 19 of figure 14 by using a Table 21 as an expansion of Table 18 of figure 13 for the case of 4 spatial streams. In the case of 4 spatial stream, Table 21 illustrated in figure 19 contains 64 entries, namely 20 EQM entries and 44 (14+10+10+10) UEQM entries, i.e. it contains the additional 10 combinations resulting from the new pattern {M, M-l, M-l, M-2}. For the case of 2 or 3 spatial streams, Table 18 may be used. Each further WLAN station 120 may decode its own indication (i.e. it does not care about UEQM of other STAs).

[0139] Table 21 of figure 19 depicts an example for the EQM+UEQM signaling for 4 spatial streams. The first UEQM entry {MCS1, MCS1, MCS1, MCSO} is the first MCS combination of the first MCS pattern as can be seen in Table 12 described above. The other UEQM MCS combinations described in Table 21 are the first MCS combination of the other MCS patterns of 4 spatial streams and can be seen in Table 20 (M, M-l, M-l, M-2), Table 14 (M, M, M-l, M-2) and Table 13 (M, M, M, M-2) described above.

[0140] According to a further embodiment shown in figure 20 (which is a variant of the user field 300 of figure 2 and some of the embodiments described above) the user field 400 generated by the WLAN station 110 for UEQM transmission signaling may comprise a merged MCS / UEQM field 420 of 6 (consecutive) bits and a Spatial Configuration field 440 of 4 bits. Like the user field 300 of figure 2, the user field 400 shown in figure 20 in addition to the merged MCS / UEQM field 420 and the Spatial Configuration field 440 may further comprise the Station ID field 410 and the Coding bit field 430.

[0141] Figure 21 shows a flow diagram illustrating a method 2100 of operating a WLAN station, such as the WLAN station 110 of figure 1 for single user, SU, or multi user, MU, communication with one or more further WLAN stations, such as the further WLAN stations 120 of figure 1 via one or more spatial streams using an equal modulation, EQM, mode or an unequal modulation, UEQM, mode based on a plurality of modulation and coding schemes, MCSs, including 16 legacy MCSs and a plurality of additional MCSs. The method 2100 comprises a step 2101 of sending an EHT or UHR Physical Layer Protocol Data Unit, PPDU, including a preamble to the one or more further WLAN stations 120, wherein the preamble comprises one or more user fields 200; 300; 400, As already described above, each user field 200; 300; 400 has a format in accordance with the IEEE 802.1 Ibe, IEEE 802.11 bn or IEEE 802.1 lax standard, wherein each user field 200; 300; 400 is configured to encode the plurality of MCSs, i.e. the 16 legacy MCSs and the plurality of additional MCSs not currently defined by the IEEE 802.11 framework of standards.

[0142] As the method 2100 can be implemented by the WLAN station 110, further features of the method 2100 result directly from the functionality of the WLAN station 110 as well as its different embodiments described above and below.

[0143] The person skilled in the art will understand that the "blocks" ("units") of the various figures (method and apparatus) represent or describe functionalities of embodiments of the present disclosure (rather than necessarily individual "units" in hardware or software) and thus describe equally functions or features of apparatus embodiments as well as method embodiments (unit = step).

[0144] In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus, and method may be implemented in other manners. For example, the described embodiment of an apparatus is merely exemplary. For example, the unit division is merely logical function division and may be another division in an actual implementation. For example, a plurality of units or components may be combined or integrated into another system, or some features may be ignored or not performed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented by using some interfaces. The indirect couplings or communication connections between the apparatuses or units may be implemented in electronic, mechanical, or other forms.

[0145] The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments. In addition, functional units in the embodiments of the invention may be integrated into one processing unit, or each of the units may exist alone physically, or two or more units are integrated into one unit.

Claims

1. CLAIMS1. A wireless local area network, WLAN, station (110; 120) for single user, SU, or multi user, MU, communication with one or more further WLAN stations (120; 110) via one or more spatial streams using an equal modulation, EQM, mode or an unequal modulation, UEQM, mode based on a plurality of modulation and coding schemes, MCSs, including 16 legacy MCSs and a plurality of additional MCSs, wherein the WLAN station (110; 120) is configured to: send an EHL or UHR Physical Layer Protocol Data Unit, PPDU, including a preamble to the one or more further WLAN stations (120; 110), wherein the preamble comprises one or more user fields (200; 300; 400), wherein each user field (200; 300; 400) has a format in accordance with the IEEE 802.1 Ibe, IEEE 802.1 Ibn or IEEE 802.1 lax standard and wherein each user field (200; 300; 400) is configured to encode the plurality of MCSs.

2. The WLAN station (110; 120) of claim 1, wherein each user field (200) in accordance with the IEEE 802.1 Ibe, IEEE 802.1 Ibn or IEEE 802.1 lax standard comprises a STA ID subfield (210), anMCS subfield (220), a reserved bit subfield (230), an NSS subfield (240), a BFed subfield (250) and a Coding subfield (260).

3. The WLAN station (110; 120) of claim 2, wherein the STA ID subfield (210) has a size of 11 bits, the MCS subfield (220) has a size of at least 4 bits, the reserved bit subfield (230) has a size of 1 bit, the NSS subfield (240) has a size of at least 4 bits, the BFed subfield (250) has a size of 1 bit and the Coding subfield (260) has a size of 1 bit.

4. The WLAN station (110; 120) of claim 2 or 3, wherein a bit of the NSS subfield (240) of each user field (200) indicates a first encoding mode and a second encoding mode.

5. The WLAN station (110; 120) of claim 4, wherein in the first encoding mode the further bits of the NSS subfield (240) indicate the number of spatial streams and the bits of the MCS subfield (220) indicate one of the 16 legacy MCSs.

6. The WLAN station (110; 120) of claim 4 or 5, wherein in the second encoding mode the further bits of the NSS subfield (240) indicate the number of spatial streams and 2 bits of the MCS subfield (220) indicate the EQM mode and 2 further bits of the MCS subfield (220) indicate one of the plurality of additional MCSs.

7. The WLAN station (110; 120) of claim 6, wherein a bit combination of the 2 MSBs of the MCS subfield (220) indicates the EQM mode and the 2 LSBs of the MCS subfield (220) indicate one of the plurality of additional MCSs.

8. The WLAN station (110; 120) of claim 6 or 7, wherein three bit combinations of the 2 MSBs of the MCS subfield (220) indicate the UEQM mode and the 3 LSBs of the NSS subfield (240) indicate one of 8 sets of modulation combinations, wherein each modulation combination defines the number of spatial streams and a pattern of modulation order differences used for the spatial streams and wherein the 4 bits of the MCS subfield (220) indicate for each of the 8 sets of modulation combinations a modulation combination.

9. The WLAN station (110; 120) of claim 6 or 7, wherein the 3 LSBs of the NSS subfield (240) together with the 4 bits of the MCS subfield (220) indicate one of a plurality of modulation combinations, wherein each modulation combination defines the number of spatial streams and the MCS used for each spatial stream.

10. The WLAN station (110; 120) of claim 2 or 3, wherein the reserved bit subfield (230) of each user field (200) indicates the EQM mode or the UEQM mode.

11. The WLAN station (110; 120) of claim 10, wherein for the EQM mode 3 bits of the NSS subfield (240) indicate the number of spatial streams and wherein the 4 bits of the MCS subfield (220) together with the remaining bit of the NSS subfield (240) indicate one of the plurality of MCSs.

12. The WLAN station (110; 120) of claim 10, wherein a bit of the NSS subfield (240) of each user field (200) indicates a first encoding mode and a second encoding mode.

13. The WLAN station (110; 120) of claim 12, wherein in the first encoding mode the 3 further bits of the NSS subfield (240) indicate the number of spatial streams and the 4 bits of the MCS subfield (220) indicate one of the 16 legacy MCSs.

14. The WLAN station (110; 120) of claim 12 or 13, wherein in the second encoding mode the 3 further bits of the NSS subfield (240) indicate the number of spatial streams and 2 or more bits of the MCS subfield (220) indicate one of the plurality of additional MCSs.

15. The WLAN station (110; 120) of claim 10, wherein for the UEQMmode 3 bits of the MCS subfield (220) indicate one of 8 sets of modulation combinations, wherein each modulation combination defines the number of spatial streams and a pattern of modulation order differences used for the spatial streams and wherein the 4 bits of the NSS subfield (240) indicate for each of the 8 sets of modulation combinations a modulation combination.

16. The WLAN station (110; 120) of claim 10, wherein for the UEQM mode 3 bits of the NSS subfield (240) indicate one of 8 sets of modulation combinations, wherein each modulation combination defines the number of spatial streams and a pattern of modulation order differences used for the spatial streams and wherein the 4 bits of the MCS subfield (220) indicate for each of the 8 sets of modulation combinations a modulation combination.

17. The WLAN station (110; 120) of claim 10, wherein for the UEQM mode the 4 bits of the MCS subfield (220) together with at least 3 bits of the NSS subfield (240) indicate a plurality of modulation combinations, wherein each modulation combination defines the number of spatial streams and a pattern of modulation order differences used for the spatial streams.

18. The WLAN station (110; 120) of claim 10, wherein for the UEQM mode the 4 bits of the NSS subfield (240) indicate the MCS of a first spatial stream of the one or more spatial streams and wherein at least 3 bits of the MCS subfield (220) indicate one of 8 sets of modulation combinations, wherein each modulation combination defines the number of spatial streams and a pattern of modulation order differences used for these spatial streams.

19. The WLAN station (110; 120) of claim 10, wherein for the UEQM mode the 4 bits of the MCS subfield (220) indicate the MCS of a first spatial stream of the one or more spatial streams and wherein at least 3 bits of the NSS subfield (240) indicate one of 8 sets of modulation combinations, wherein each modulation combination defines the number of spatial streams and a pattern of modulation order differences used for these spatial streams.

20. The WLAN station (110; 120) of claim 10, wherein the reserved bit (230) of each user field (200) indicates a first encoding mode and a second encoding mode.

21. The WLAN station (110; 120) of claim 20, wherein in the first encoding mode at least 3 bits of the NSS subfield (240) indicate the number of spatial streams and the 4 bits of the MCS subfield (220) indicate one of the 16 legacy MCSs.

22. The WLAN station (110; 120) of claim 20 or 21, wherein in the second encoding mode at least 3 bits of the NSS subfield (240) indicate the number of spatial streams and 2 bits of the MCS subfield (220) indicate the UEQM mode and 2 further bits of the MCS subfield (220) indicate one of the plurality of additional MCSs.

23. The WLAN station (110; 120) of claim 1, wherein each user field (300) in accordance with the IEEE 802.1 Ibe, IEEE 802.11 bn or IEEE 802.11 ax standard comprises a STA ID subfield (310) of 11 bits, an MCS subfield (320) of 4 bits, a Coding subfield (330) of 1 bit, and a Spatial Configuration subfield (340) of 6 bits.

24. The WLAN station (110; 120) of claim 23, wherein 4 bits of the Spatial Configuration subfield (340) of each user field (300) indicate the number of spatial streams and wherein the 4 bits of the MCS subfield (320) together with the other 2 bits of the Spatial Configuration subfield (340) indicate a plurality of modulation combinations, wherein a first subset of the plurality of modulation combinations defines for the EQM mode up to 20 MCSs and a second subset of the plurality of modulation combinations defines for the UEQM mode the number of spatial streams and the MCS for each spatial stream.

25. The WLAN station (110; 120) of claim 10, wherein for the UEQM mode 4 bits of the MCS subfield (220) indicate one of 9 sets of modulation combinations, wherein each modulation combination defines the number of spatial streams and a pattern of modulation order differences used for these spatial streams and wherein the 4 bits of the NSS subfield (240) indicate for each of the 9 sets of modulation combinations a modulation combination.

26. The WLAN station (110; 120) of claim 10, wherein for the UEQM mode 4 bits of the NSS subfield (240) indicate one of 9 sets of modulation combinations, wherein each modulation combination defines the number of spatial streams and a pattern of modulation order differences used for these spatial streams and wherein the 4 bits of the MCS subfield (240) indicate for each of the 9 sets of modulation combinations a modulation combination.

27. The WLAN station (110; 120) of claim 10, wherein for the UEQM mode the 4 bits of the MCS subfield (220) together with at least 3 bits of the NSS subfield (240) indicate a plurality of modulation combinations, wherein each modulation combination defines the number of spatial streams and a pattern of modulation order differences used for these spatial streams.

28. The WLAN station (110; 120) of claim 10, wherein for the UEQM mode the 4 bits of the NSS subfield (240) indicate the MCS of a first spatial stream of the one or more spatial streams and wherein 4 bits of the MCS subfield (220) indicate one of 9 sets of modulation combinations, wherein each modulation combination defines the number of spatial streams and a pattern of modulation order differences used for these spatial streams.

29. The WLAN station (110; 120) of claim 10, wherein for the UEQM mode the 4 bits of the MCS subfield (220) indicate the MCS of a first spatial stream of the one or more spatial streams and wherein 4 bits of the NSS subfield (240) indicate one of 9 sets of modulation combinations, wherein each modulation combination defines the number of spatial streams and a pattern of modulation order differences used for these spatial streams.

30. The WLAN station (110; 120) of claim 1, wherein each user field (400) comprises a STA ID subfield (410) of 11 bits, a MCS / UEQM subfield (420) of at least 6 bits, a Coding subfield (430) of 1 bit, and a Spatial Configuration subfield (440) of at least 4 bits and wherein the MCS / UEQM subfield (420) is configured to encode the plurality of MCSs and wherein the at least 6 bits of the MCS / UEQM subfield (420) and the at least 4 bits of the Spatial Configuration subfield (440) encode the plurality of MCSs.

31. The WLAN station (110; 120) of claim 1, wherein each user field (300) in accordance with the IEEE 802.1 Ibe, IEEE 802.11 bn or IEEE 802.1 lax standard comprises a STA ID subfield (310) of 11 bits, an MCS subfield (320) of 4 bits, a Coding subfield (330) of 1 bit, and a Spatial Configuration subfield (340) of 6 bits.

32. A method (2100) of operating a wireless local area network, WLAN, station (110; 120) for single user, SU, or multi user, MU, communication with one or more further WLAN stations (120; 110) via one or more spatial streams using an equal modulation, EQM, mode or an unequal modulation, UEQM, mode based on a plurality of modulation and coding schemes, MCSs, including 16 legacy MCSs and a plurality of additional MCSs, wherein the method (2100) comprises: sending (2101) an EHT or UHR Physical Layer Protocol Data Unit, PPDU, including a preamble to the one or more further WLAN stations (120; 110), wherein the preamble comprises one or more user fields (200; 300; 400), wherein each user field (200; 300; 400) has a format in accordance with the IEEE 802.1 Ibe, IEEE 802.11 bn or IEEE 802.1 lax standard and wherein each user field (200; 300; 400) is configured to encode the plurality of MCSs.

33. A computer program product comprising a computer-readable storage medium for storing program code which causes a computer or a processor to perform the method (2100) of claim 32 when the program code is executed by the computer or the processor.

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