Devices and methods for improved WLAN communication

Abstract

NOT VISIBLE DUE TO STATUS OF PATENT

Description

[0001] DEVICES AND METHODS FOR IMPROVED WLAN COMMUNICATION

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to wireless communications. More specifically, the present disclosure relates to devices and methods for improved communication 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. WLANs allow access point, APs, and non-AP stations to operate at different frequency bands, such as 2.4GHz, 5GHz and 6GHz bands. Each band has different requirements and regulation limits. The 6GHz band, for instance, has very strong restrictions regarding the Power Spectral Density, PSD, especially for non-AP stations, in that the total power transmitted within each 1MHz is limited to values defined by the IEEE 802.11 framework of standards. These requirements limit the link budget of WLAN communication and lead to very short operation distance.

[0006] To overcome this issue and allow communication over a longer range, the 802.1 Ibn standard amendment has introduced the idea of a distributed tone resource unit, DRU. A regular resource unit, RU, such as the exemplary 26-tone RU 10 illustrated in Fig. 1 , consists of several consecutive tones. The idea of DRU is to spread the tones of all the RU s over a larger bandwidth, BW, and to produce a tone plan where there are a few tones of each DRU within each 1MHz, as illustrated by the exemplary 26-tone RU 20 in Fig. 1. Due to the tone spreading of a DRU the PSD corresponding to the non-AP STA that transmits using this DRU is reduced and an additional power gain is available which may imply longer operating range and better performance. This technology is applicable for all transmissions, but the largest impact is achieved in case of SU and TB UL transmissions.

[0007] SUMMARY

[0008] It is an objective of the present disclosure to provide devices and methods for improved communication 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, allowing for an increased operation range and / or an increased communication performance.

[0009] 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.

[0010] According to a first aspect a non-access point, non-AP, station for communication with an associated AP is provided. The non-AP station according to the first aspect is configured to transmit a data frame and / or a management frame with a frame header to the AP. The frame header comprises an uplink, UL, Power Headroom, UPH, value corresponding to the difference between a maximum UL transmit power and the actual UL transmit power for the current transmission and an indication indicative of whether the maximum UL transmit power used for determining the UPH value is bounded by a maximum power spectral density, PSD, limit. Thus, the non-AP station according to the first aspect provides information that can be utilized by the AP to increase the communication range and / or performance with the non-AP STA.

[0011] In a further possible implementation form, the non-AP station is further configured to : receive a trigger frame from the AP, wherein the trigger frame comprises a mode indication of a regular resource unit, RU, transmission mode or a distributed RU, DRU, transmission mode and wherein the mode indication is based on the indication indicative of whether the maximum UL transmit power used for determining the UPH value is bounded by the maximum PSD limit; and transmit a trigger-based PPDU, i.e. an UL data transmission to the AP according to the transmission mode indicated by the mode indication of the preceding trigger frame.

[0012] In a further possible implementation form, the frame header comprises a UPH control field, wherein the UPH control field comprises the indication indicative of whether the maximum UL transmit power used for determining the UPH value is bounded by the maximum PSD limit.

[0013] In a further possible implementation form, the frame header further comprises a PSD Residual Headroom, PRH, value corresponding to the difference between a maximum achievable UL transmit power, i.e. the Radio maximal UL transmit power, of the non-AP station and the maximum UL transmit power bounded by the PSD limit.

[0014] In a further possible implementation form, the frame header comprises a PRH control field, wherein the PRH control field comprises the PRH value.

[0015] In a further possible implementation form, the PRH control field has a valid value, in case the indication indicates that the maximum UL transmit power used for determining the UPH value is bounded by the maximum PSD limit.

[0016] In a further possible implementation form, the frame header further comprises a DRU Gain Headroom, DGH, value corresponding to the difference between a minimum UL transmit power of the non-AP station for achieving a target RSSI value indicated by the AP and the maximum UL transmit power bounded by the PSD limit, when the value of the minimum UL transmit power for achieving the target RSSI value indicated by the AP is greater than the maximum UL transmit power value.

[0017] In a further possible implementation form, the frame header comprises a DGH control field, wherein the DGH control field comprises the DGH value.

[0018] In a further possible implementation form, the frame header further comprises a Negative DRU Headroom, NDH, value corresponding to the difference between the actual UL transmit power for the current transmission and the maximum UL transmit power bounded by the PSD limit, when the DRU transmission mode is applied, i.e. selected.

[0019] In a further possible implementation form, the frame header comprises an NDH control field, wherein the NDH control field comprises the NDH value.

[0020] In a further possible implementation form, the non-AP station is configured to receive a PSD Limit Info Request Poll trigger frame from the AP, wherein the PSD Limit Info Request Poll trigger frame is indicative of a target RSSI value and request for an information of one or more of the PRH control field, the DGH control field, and / or the NDH control field.

[0021] In a further possible implementation form, in response to receiving the PSD Limit Info Request Poll trigger frame from the AP, the non-AP station is configured to send to the AP for the indicated target RSSI value the one or more of the PRH control field, the DGH control field, and / or the NDH control field indicated by the PSD Limit Info Request Poll trigger frame. In a further possible implementation form, the non-AP station is configured to send the one or more of the PRH control field, the DGH control field, and / or the NDH control field to the AP as part of an Initial Control frame, ICF, an Initial Control Response, ICR, frame or a Control Response frame, CRF.

[0022] According to a second aspect a method is provided for operating a non-access point, non-AP, station for communication with an associated AP. The method according to the second aspect comprises transmitting a data frame and / or a management frame with a frame header to the AP, wherein the frame header comprises an uplink, UL, Power Headroom, UPH, value corresponding to the difference between a maximum UL transmit power and the actual UL transmit power for the current transmission and an indication indicative of whether the maximum UL transmit power used for determining the UPH value is bounded by a maximum power spectral density, PSD, limit.

[0023] The method according to the second aspect can be performed by the non-AP station according to the first aspect. Thus, further features of the method according to the second aspect result directly from the functionality of the non-AP station according to the first aspect as well as its different implementation forms described above and below.

[0024] According to a third aspect an access point, AP, for communication with one or more associated non-AP station is provided. The AP according to the third aspect is configured to receive a data frame and / or a management frame with a frame header from the non-AP station, wherein the frame header comprises an uplink, UL, Power Headroom, UPH, value corresponding to the difference between a maximum UL transmit power and the actual UL transmit power for the [current] transmission and an indication indicative of whether the maximum UL transmit power used for determining the UPH value is bounded by a maximum power spectral density, PSD, limit.

[0025] In a further possible implementation form, the AP according to the third aspect is further configured to: send a trigger frame to the non-AP station, wherein the trigger frame comprises a mode indication of a regular resource unit, RU, transmission mode or a distributed RU, DRU, transmission mode, wherein the mode indication is based on the indication indicative of whether the maximum UL transmit power used for determining the UPH value is bounded by the maximum PSD limit; and receive a trigger-based PPDU, i.e. an UL data transmission, from the non-AP station according to the transmission mode indicated by the mode indication of the [preceding] trigger frame.

[0026] In a further possible implementation form, the frame header comprises a UPH control field, wherein the UPH control field comprises the indication indicative of whether the maximum UL transmit power used for determining the UPH value is bounded by the maximum PSD limit.

[0027] In a further possible implementation form, the frame header further comprises a PSD Residual Headroom, PRH, value corresponding to the difference between a maximum achievable UL transmit power, i.e. the Radio maximal UL transmit power, of the non-AP station and the maximum UL transmit power bounded by the PSD limit.

[0028] In a further possible implementation form, the frame header comprises a PRH control field, wherein the PRH control field comprises the PRH value.

[0029] In a further possible implementation form, the PRH control field has a valid value, in case the indication indicates that the maximum UL transmit power used for determining the UPH value is bounded by the maximum PSD limit. In a further possible implementation form, the frame header further comprises a DRU Gain Headroom, DGH, value corresponding to the difference between a minimum UL transmit power of the non-AP station for achieving a target RSSI value indicated by the AP and the maximum UL transmit power bounded by the maximum PSD limit, when the value of minimum UL transmit power for achieving the target RSSI value indicated by the AP is greater than the maximum UL transmit power value.

[0030] In a further possible implementation form, the frame header comprises a DGH control field, wherein the DGH control field comprises the DGH value.

[0031] In a further possible implementation form, the frame header further comprises a Negative DRU Headroom, NDH, value corresponding to the difference between the actual UL transmit power for the current transmission and the maximum UL transmit power bounded by the maximum PSD limit, when the DRU transmission mode is applied, i.e. selected.

[0032] In a further possible implementation form, the frame header comprises an NDH control field, wherein the NDH control field comprises the NDH value.

[0033] In a further possible implementation form, the AP is configured to send a PSD Limit Info Request Poll trigger frame to the one or more non-AP stations, wherein the PSD Limit Info Request Poll trigger frame is indicative of a target RSSI value and request for an information of one or more of the PRH control field, the DGH control field, and / or the NDH control field.

[0034] In a further possible implementation form, in response to sending the PSD Limit Info Request Poll trigger frame to the one or more non-AP stations, the AP is configured to receive from each of the one or more solicited non-AP stations for the indicated target RSSI value the one or more of the PRH control field, the DGH control field, and / or the NDH control field indicated by the preceding PSD Limit Info Request Poll trigger frame.

[0035] In a further possible implementation form, the AP is configured to receive the one or more of the PRH control field, the DGH control field, and / or the NDH control field from the non-AP station as part of an Initial Control frame, ICF, an Initial Control Response, ICR, frame or a Control Response frame, CRF.

[0036] According to a fourth aspect a method is provided for operating an access point, AP, for communication with one or more associated non-AP stations. The method according to the fourth aspect comprises the step of receiving a data frame and / or a management frame with a frame header from each of the one or more non-AP stations, wherein the frame header comprises an uplink, UL, Power Headroom, UPH, value corresponding to the difference between a maximum UL transmit power and the actual UL transmit power for the current transmission and an indication indicative of whether the maximum UL transmit power used for determining the UPH value is bounded by a maximum power spectral density, PSD, limit.

[0037] The method according to the fourth aspect can be performed by the AP according to the third aspect. Thus, further features of the method according to the fourth aspect result directly from the functionality of the AP according to the third aspect as well as its different implementation forms described above and below.

[0038] According to a fifth 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 or the method according to the fourth aspect, when the program code is executed by the computer or the processor.

[0039] 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In the following, embodiments of the present disclosure are described in more detail with reference to the attached figures and drawings, in which:

[0041] Fig. 1 shows a schematic diagram illustrating a standard RU and a distributed RU that may be used by an AP and a non- AP station according to an embodiment;

[0042] Fig. 2 shows a schematic diagram illustrating an AP according to an embodiment in communication with a plurality of non-AP stations; according to an embodiment

[0043] Fig. 3a illustrates for an exemplary transmission scenario the relation between a current transmission power, a maximal power value calculated within an allocated RU due to PSD limit for the transmission, a maximum transmission power and a UPH value;

[0044] Fig. 3b shows a UPH control field format that is included in a frame header of a frame transmitted by a non-AP station to an AP according to an embodiment, wherein the UPH control field includes a UPH value and a PSD limit subfield;

[0045] Fig. 4a illustrates for an exemplary transmission scenario the relation between a current transmission power, a maximal power value calculated within an allocated RU due to PSD limit for the transmission, a maximum transmission power and a PRH value;

[0046] Fig. 4b shows a PRH control field format that is included in a frame header of a frame transmitted by a non-AP station to an AP according to an embodiment, wherein the PRH control field includes a PRH value;

[0047] Fig. 5a illustrates for an exemplary transmission scenario the relation between a current required transmission power, a maximal power value calculated within an allocated RU due to PSD limit for the transmission, a maximum Radio transmission power and a DGH value;

[0048] Fig. 5b shows a DGH control field format that is included in a frame header of a frame transmitted by a non-AP station to an AP according to an embodiment, wherein the DGH control field includes a DGH value;

[0049] Fig. 6 shows a NDH control field format that is included in a frame header of a frame transmitted by a non-AP station to an AP according to an embodiment, wherein the NDH control field includes a NDH value;

[0050] Fig. 7 shows a flow diagram illustrating steps of a method of operating a non-AP station according to an embodiment; and

[0051] Fig. 8 shows a flow diagram illustrating a method of operating an AP according to an embodiment.

[0052] In the following, identical reference signs refer to identical or at least functionally equivalent features.

[0053] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] 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.

[0055] 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.

[0056] Fig. 2 shows a wireless communication network 100 in the form of 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 an access point, AP, 110 in communication with a plurality of associated non-AP stations 120. As illustrated in Fig. 2, 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.

[0057] As further illustrated in Fig. 2, 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.

[0058] Likewise, as indicated in Fig. 2, each non-AP station 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.

[0059] Before describing detailed embodiments of the non-AP stations 120 according to an embodiment and the AP 110 according to an embodiment, 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:

[0060] A-MPDU Aggregate MPDU A-MSDU Aggregate MSDU AP Access Point BA Block Acknowledgement

[0061] BSS Basic Service Set

[0062] BW Bandwidth

[0063] CSI Channel State Information

[0064] DGH DRU Gain Headroom

[0065] DL Downlink

[0066] DRU Distributed Resource Unit

[0067] EHT Extremely High Throughput

[0068] EVM Error Vector Magnitude

[0069] FCS Forward Correction Sequence

[0070] LAN Local Area Network

[0071] LLC Logical Link Control

[0072] MAC Medium Access Control

[0073] MIMO Multiple In Multiple Out

[0074] ML Maximum Likelihood

[0075] MPDU MAC Protocol Data Unit

[0076] NDH Negative DRU Headroom

[0077] NDP Null Data PPDU

[0078] PER Packet Error Ratio

[0079] PHY Physical (layer)

[0080] PPDU Physical Layer Protocol Data Unit

[0081] PRH PSD Residual Headroom

[0082] PSD Power Spectral Density

[0083] RS SI Received Signal Strength Indicator

[0084] RU Resource Unit

[0085] SNR Signal to Noise Ratio

[0086] STA Station

[0087] TB Trigger Based

[0088] TF Trigger Frame

[0089] UL Uplink

[0090] UPH Uplink Power Headroom

[0091] WLAN Wireless Local Area Network

[0092] UHR Ultra High Reliability

[0093] As used herein, an access point (AP), such as the AP 110 illustrated in Fig. 2, is a wireless station (STA) that provides access to other networks. An AP can support many connected, i.e. associated non-AP STAs, such as the non-AP stations 120 illustrated in Fig. 2. APs use control information to control traffic flow over the wireless medium among all associated non- AP STAs within a BSS.

[0094] As used herein, there are three main types of frames communicated between WLAN STAs, namely data, management, and control frames. Data traffic is exchanged between two or more stations (STAs) in a WLAN to facilitate communication, one of which is typically an AP. The data frames are either generated by the two or more STAs and / or by an external network. This traffic is delivered in a secured manner over the WLAN when the AP and the corresponding non-AP STAs negotiate a cryptographic encapsulation method and keys to encrypt the data traffic. Management frames are exchanged between the AP and one or more non-AP STAs in a BSS to establish and maintain state of data communications. Security can be negotiated to encrypt or authorize data and / or management frames. Control frames are exchanged between the AP and the non-AP STAs in a BSS to control the flow of the data frame exchange.

[0095] Fig. 3a illustrates for an exemplary transmission scenario the relation between a current transmission power 303, a maximum power value calculated within an allocated RU due to power spectral density, PSD, limit 302 for the transmission, a maximum Radio transmission power 301 and an Uplink Power Headroom value 304. In the example shown in Fig. 3, the maximum power value calculated within an allocated RU due to PSD limit 302 is smaller than the maximum Radio transmission power 301, for example, by 2dB.

[0096] As will be appreciated, the maximal power value calculated within an allocated RU due to PSD limit 302 is defined as an absolute power value. Thus, in order to decide that DRU mode is required, the absolute transmit power of a non-AP station should be known to the AP. When a TB PPDU is triggered by an AP, the absolute transmit power of the non-AP station is not known to the AP. When an AP initiates an UL MU transmission, using a trigger frame, according to the IEEE 802.11 framework of standards it has to set a target RS SI value for each of the triggered non-AP stations or to instruct each non-AP station to respond with its maximum transmit power. The non-AP station calculates the required transmit power based on the received AP signal strength and the target RSSI value provided within the Trigger Frame.

[0097] According to the IEEE 802.11 framework of standards the only information provided by a non-AP station when TB PPDU is transmitted is the Uplink Power Headroom value 304, which indicates the difference between the current transmit power 303 and the maximum transmit power 301 allowed for a current transmit configuration. As defined by the IEEE 802.11 framework of standards, the maximum transmit power value 301 is limited by one of the local restrictions / regulations or by Radio properties of the transmitter.

[0098] Thus, although a conventional AP may know the difference between the maximum allowed transmit power and the current power, the absolute transmit power 301 of the non-AP station is unknown. Moreover, the AP has no information about which of the various factors actually limits the current power transmitted by the non-AP station. In particular, the conventional AP has no information about whether the maximum transmit power is limited due to the maximal power value calculated within an allocated RU due to PSD limit 302. For instance, in the example shown in Fig. 3a the current maximum power 303 is bounded by the maximal power value calculated within an allocated RU due to PSD limit 303, and, thus the reported UPH value 304 is 3dB. However, in the exemplary scenario of Fig. 3a the radio interface of the non-AP station actually allows to transmit with a higher power value 301 than the maximal power value calculated within an allocated RU due to PSD limit 302 by an additional 2dB. Consequently, in this scenario by switching to a DRU transmission mode, the non-AP STA can increase its headroom by the additional 2 dB (since the maximal power value calculated within an allocated RU due to PSD limit will not bound the maximal transmit power, but only the maximal radio transmit power). However, as described above, according to the IEEE 802.11 framework of standards AP is not aware of the “potentially additional 2dB” gap so eventually it has no information nor motivation to make such a decision. In other words, a conventional AP has no information for determining when a DRU transmission mode should be applied resulting in an efficient usage of the DRU transmission mode.

[0099] To address the issues outlined above, according to embodiments disclosed herein the non-AP stations 120 shown in Fig. 2 are configured to use indications that will provide the AP 110 shown in Fig. 2 with the required information to make a decision when DRU transmission mode should be applied. Embodiments disclosed herein are based on the assumption that the currently standardized principles of power setting for TB PPDU are reused, in particular in the upcoming standard amendment 802.1 Ibn. Thus, embodiments disclosed herein add several indications that provide the required information regarding the PSD limit restriction (if exists) and the DRU mode application in an efficient manner, including: an indication if the current maximum power 303 is bounded by the PSD limit 303; an indication of a residual headroom available if the DRU transmission mode is applied (and the bounding maximal power value calculated within an allocated RU due to PSD limit increases); an indication of the DRU gain is required to achieve an indicated target RS SI in case the bounding maximal power value calculated within an allocated RU due to PSD limit is lower than the calculated transmit power due to the target RSSI; and / or an indication of the gap, i.e. difference between the current transmit power 303 and the bounding maximal power value calculated within an allocated RU due to PSD limit 302. Moreover, embodiments disclosed herein provide a request poll frame that might be used by the AP 110 according to an embodiment to request the information mentioned above.

[0100] More specifically, each non-AP station 120 of Fig. 2 is configured to transmit a data frame and / or a management frame with a frame header to the AP 110, wherein the frame header comprises an uplink, UL, Power Headroom, UPH, value 304 corresponding to the difference between the maximum UL transmit power 301, 302 and an actual UL transmit power 303 for the current transmission and an indication indicative of whether the maximum UL transmit power 301, 302 used by the non- AP station 120 for determining the UPH value 304 is bounded by the maximum power value calculated within an allocated RU due to power spectral density, PSD, limit 302. In other words, in addition to the conventional UPH value the frame header further comprises information for the AP 110 whether the provided UPH value 304 has been determined by the non- AP station 120 relative to the maximum power value calculated within an allocated RU due to PSD limit 302.

[0101] In an embodiment, as illustrated in Fig. 3b, the frame header of the data frame and / or management frame transmitted by the non-AP station 120 and received by the AP 110 comprises a UPH control field 310, wherein the UPH control field 310 comprises a PSD limit subfield 313 containing the indication indicative of whether the maximum UL transmit power 301, 302 used by the non-AP station 120 for determining the UPH value 304 is bounded by the maximum power value calculated within an allocated RU due to PSD limit 302. In the embodiment shown in Fig. 1, the PSD limit field 313 may be a single bit, i.e. a Boolean indication in the form of a flag bit. In an embodiment, if indicated (i.e. the PSD limit subfield 313 value is set to 1), the AP 110 may consider switching to the DRU transmission mode, as will be described in more detail in the following. In addition to the PSD limit subfield 313, the UPH control field 310 comprises a UPH subfield 313 containing the UPH value 304 (which may have a size of 5 bits). Moreover, the UPH control field 310 may comprise a Minimum Transmit Power Flag element 312 and a reserved bit 314.

[0102] In an embodiment, after transmitting the frame to the AP 110 including the indication indicative of whether the maximum UL transmit power 301, 302 used by the non-AP station 120 for determining the UPH value 304 is bounded by the maximum power value calculated within an allocated RU due to PSD limit 302, each non-AP station 120 is further configured to receive a trigger frame from the AP 110, wherein the trigger frame comprises a mode indication of a regular resource unit, RU, transmission mode (i.e. a transmission mode based on regular, i.e. non-distributed RUs allocation) or a distributed RU, DRU, transmission mode (i.e. a transmission mode based on DRUs allocation) and wherein the mode indication selected by the AP 110 is based on the indication indicative of whether the maximum UL transmit power 301, 302 used by the non-AP station 120 for determining the UPH value 304 is bounded by the maximum power value calculated within an allocated RU due to PSD limit 302. Based on the indication of the transmission mode provided by the AP 110, i.e. regular RU transmission mode or DRU transmission, the non-AP station transmits a TB PPDU to the AP 110 within the allocated RU or DRU. As will be appreciated, because of the additional information available to the AP 110 due to the indication the AP 110 may select the transmission mode that allows for a higher maximum transmission power, therefore increasing the transmission range with the non-AP.

[0103] Fig. 4a illustrates for an exemplary transmission scenario the relation between the current transmission power 303 , the maximal power value calculated within an allocated RU due to the PSD limit 302 for the transmission, the maximum Radio transmission power 301 and a PSD Residual Headroom (PRH) value 404, while Fig. 4b shows a PRH control field 410 included in the frame header of the frame transmitted by the non-AP station 120 to the AP 110 according to an embodiment. In other words, in an embodiment, the frame header of the frame transmitted by the non-AP station 120 to the AP 110 according to an embodiment may comprises in addition to the UPH control field 310 shown in Fig. 3b the PRH control field shown in Fig. 4b.

[0104] In an embodiment, the PRH control field 410 illustrated in Fig. 4b may be a new A-Control field (similar to UPH control field 310 of Fig. 3b). In case the maximum transmit power is bounded by the maximal power value calculated within an allocated RU due to PSD limit value 302 (as in the case for the scenario illustrated in Fig. 4a), the non-AP station 120 may be configured to further indicate the gap between the maximal power value calculated within an allocated RU due to PSD limit value 302 and the next bound of the maximum transmit power level 301 (e.g. defined by Radio transmit power). The PRH control field 410 may comprise a PRH subfield 411 (which may have a size of 4 bits) containing the PRH value 404 as well as one or more reserved bits 412 for future usage. As will be appreciated, by means of the PRH value 404, the AP 101 according to an embodiment is provided with information regarding the DRU gain that might be achieved (if the DRU mode will be applied). This gain, by way of example, has a value of 2dB in the scenario shown in Fig. 4a. In an embodiment, the PRH control field 410 may be transmitted by the non-AP station 120 in addition to the UPH control field 310, only when PSD Limit subfield 313 is set to “True” value.

[0105] Another possible scenario is when a requested transmit power 501 (as derived from the Target RSSI value defined by the AP 110 in the preceding trigger frame) cannot be reached by the non-AP station 120 because it is bounded by the maximal transmit power 302 as is the case for the scenario illustrated in Fig. 5a. If the maximal transmit power is bounded by the maximal power value calculated within an allocated RU due to PSD limit value 302, the non-AP station 120 may indicate a DRU Gain Headroom, DGH, value 504 that is required to reach the Requested transmit power 501 (that is derived from the indicated target RSSI value). For indicating the DGH value 504 the non-AP station may further include the DGH control field 510 shown in Fig. 5b in the original data frame or management frame transmitted to the AP 110. In other words, the DGH control field 510 can be transmitted in addition to the UPH and the PRH control fields 310, 410 described above (which will contain the same value in such case). Assuming the maximal anticipated DRU gain will be approximately 17dB, the required size of the field 511 for the DGH value 504 is 5 bits (the remaining bits of the DGH control field 510 may be reserved bits 512).

[0106] An alternative scenario is a different implementation for the transmit configuration that might be implemented by the AP 110. In an embodiment, the AP 110 may be configured to start applying the DRU transmission mode and then switch to the regular transmission mode, i.e. RU mode, for lower values of the target RSSI. As will be appreciated, however, also in this case the AP 110 does not have sufficient information for deciding when to switch to the regular transmission mode. Therefore, in an embodiment, an additional A-Control field 610 (as illustrated in Fig. 6 and referred to as Negative DRU Headroom, NDH, control field 610) may be included by the non-AP station 120 in addition to the UPH control field 310 included in the data frame and / or management frame transmitted to the AP 110. The NDH control field 310 contains in the NDH subfield 311 a NDH value, which represents the negative gap between the current transmit power 303 and the maximal power value calculated within an allocated RU due to PSD limit value 302. For example, if the AP 110 applies the DRU transmission mode and sets the target RSSI such that the current transmit power 303 of the non-AP station 120 is 6dB above maximal power value calculated within an allocated RU due to the PSD limit calculated for the same amount of DRU’s subcarriers within a regular RU 302, the non-AP station 120 indicates 6dB as the NDH value. In this manner, the AP 110 knows that if the target RSSI is reduced by more than 6dB it may switch to a regular RU transmission mode. As will be appreciated, according to an embodiment, the NDH control field 610 cannot be transmitted together with the DGH control field 510 and the PRH control field 410 as they refer to the scenario when the DRU mode is not applied.

[0107] In an embodiment, the AP 110 is configured to request any of the indications and / or control fields described above. To this end, the AP 110 may be configured to transmit a TF type PSD Limit Info Request Poll to the one or more associated non-AP stations 120. Each non-AP station 120 that receives this trigger frame responds with all the control fields as indicated by the AP 110 with respect to the target RSSI as set in the trigger frame. Thus, in an embodiment, the PSD Limit Info Request Poll trigger frame includes the following information: PRH Request bit; DRH Request bit; NDH Request bit.

[0108] In an embodiment, in response to receiving the PSD Limit Info Request Poll trigger frame from the AP 110, each solicited non-AP station 120 is configured to send to the AP 110 for the indicated target RSSI value the one or more of the PRH control field 410, the DGH control field 510, or the NDH control field 610 indicated by the PSD Limit Info Request Poll trigger frame. In an embodiment, each solicited non-AP station 120 is configured to send or be solicited for the one or more of the PRH control field 410, the DGH control field 510, or the NDH control field 610 to the AP 110 as part of an Initial Control frame, ICF, an Initial Control Response, ICR, frame or a Control Response frame, CRF.

[0109] Fig. 7 shows a flow diagram illustrating steps of a method 700 for operating one of the non-AP stations 120 of Fig. 2 for communication with the associated AP 110. The method 700 comprises a step 701 of transmitting a data frame and / or a management frame with a frame header to the AP 110, wherein the frame header comprises the uplink, UL, Power Headroom, UPH, value 304 corresponding to the difference between the maximum UL transmit power 301, 302 and the actual UL transmit power 303 for the current transmission and an indication indicative of whether the maximum UL transmit power 301, 302 used by the non-AP station 120 for determining the UPH value 304 is bounded by the maximum power value calculated within an allocated RU due to power spectral density, PSD, limit 302.

[0110] As the method 700 can be implemented by each of the non-AP stations 120, further features of the method 700 result directly from the functionality of the non-AP stations 120 as well as their different embodiments described above and below.

[0111] Fig. 8 shows a flow diagram illustrating a method 800 for operating the AP 110 of Fig. 2 for communication with the one or more associated non-AP stations 120. The method 800 comprises a step 801 of receiving a data frame and / or a management frame with a frame header from the one or more non-AP stations 120, wherein the frame header comprises the uplink, UL, Power Headroom, UPH, value 304 corresponding to the difference between the maximum UL transmit power 301, 302 and the actual UL transmit power 303 for the current transmission and the indication indicative of whether the maximum UL transmit power 301, 302 used by the non-AP station 120 for determining the UPH value 304 is bounded by the maximum power value calculated within an allocated RU due to power spectral density, PSD, limit 302.

[0112] As the method 800 can be implemented by the AP 110, further features of the method 800 result directly from the functionality of the AP 110 as well as its different embodiments described above and below.

[0113] 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).

[0114] 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. 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.

[0115] In addition, functional units in the embodiments of the disclosure 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

CLAIMS1. A non-access point, non-AP, station (120) for communication with an associated AP (110), wherein the non-AP station (120) is configured to: transmit a data frame and / or a management frame with a frame header to the AP (110), wherein the frame header comprises an uplink, UL, Power Headroom, UPH, value (304) corresponding to the difference between a maximum UL transmit power (301, 302) and an actual UL transmit power (303) for the transmission and an indication indicative of whether the maximum UL transmit power (301, 302) used for determining the UPH value (304) is bounded by a maximum power spectral density, PSD, limit (302).

2. The non-AP station (120) of claim 1, wherein the non-AP station (120) is further configured to: receive a trigger frame from the AP (110), wherein the trigger frame comprises a mode indication of a regular resource unit, RU, transmission mode or a distributed RU, DRU, transmission mode and wherein the mode indication is based on the indication indicative of whether the maximum UL transmit power (301, 302) used for determining the UPH value (304) is bounded by the maximum PSD limit (302); and transmit a PPDU to the AP (110) according to the transmission mode indicated by the mode indication of the trigger frame.

3. The non-AP station (120) of claim 1 or 2, wherein the frame header comprises a UPH control field (310) and wherein the UPH control field (310) comprises the indication indicative of whether the maximum UL transmit power (301, 302) used for determining the UPH value (304) is bounded by the maximum PSD limit (302).

4. The non-AP station (120) of claim 3, wherein the frame header further comprises a PSD Residual Headroom, PRH, value (404) corresponding to the difference between a maximum achievable UL transmit power (301) of the non-AP station (120) and the maximum UL transmit power (301, 302).

5. The non-AP station ( 120) of claim 4, wherein the frame header comprises a PRH control field (410), wherein the PRH control field (410) comprises the PRH value (404).

6. The non-AP station (120) of claim 5, wherein the PRH control field (410) has a valid value, in case the indication indicates that the maximum UL transmit power (301, 302) used for determining the UPH value (304) is bounded by the maximum PSD limit (302).

7. The non-AP station (120) of any one of the preceding claims, wherein the frame header further comprises a DRU Gain Headroom, DGH, value (504) corresponding to the difference between a minimum UL transmit power (501) of the non- AP station ( 120) for achieving a target RS SI value indicated by the AP ( 110) and the maximum UL transmit power (301, 302), when the value of the minimum UL transmit power (501) for achieving the target RSSI value indicated by the AP (110) is greater than the maximum UL transmit power value (301, 302).

8. The non-AP station (120) of claim 7, wherein the frame header comprises a DGH control field (510), wherein the DGH control field (510) comprises the DGH value (504).

9. The non-AP station (120) of claims 1 or 2, wherein the frame header further comprises a Negative DRU Headroom, NDH, value corresponding to the difference between the actual UL transmit power (303) for the transmission and the maximum UL transmit power (301, 302), when the DRU transmission mode is applied.

10. The non-AP station (120) of claim 9, wherein the frame header comprises an NDH control field (610), wherein the NDH control field ( 10) comprises the NDH value.

11. The non-AP station (120) of any one of claims 3 to 9, wherein the non-AP station (120) is configured to receive a PSD Limit Info Request Poll trigger frame from the AP (110), wherein the PSD Limit Info Request Poll trigger frame is indicative of a target RS SI value and request for an information of one or more of the PRH control field (410), the DGH control field (510), and / or the NDH control field (610).

12. The non-AP station (120) of claim 11, wherein, in response to receiving the PSD Limit Info Request Poll trigger frame from the AP (110), the non-AP station (120) is configured to send to the AP (110) for the indicated target RS SI value the one or more of the PRH control field (410), the DGH control field (510), and / or the NDH control field (610) indicated by the PSD Limit Info Request Poll trigger frame.

13. The non-AP station (120) of claim 12, wherein the non-AP station (120) is configured to send the one or more of the PRH control field (410), the DGH control field (510), and / or the NDH control field (610) to the AP (110) as part of an Initial Control frame, ICF, an Initial Control Response, ICR, frame or a Control Response frame, CRF.

14. A method (700) for operating a non-access point, non-AP, station (120) for communication with an associated AP (110), wherein the method (700) comprises: transmitting (701) a data frame and / or a management frame with a frame header to the AP (110), wherein the frame header comprises an uplink, UL, Power Headroom, UPH, value (304) corresponding to the difference between a maximum UL transmit power (301, 302) and an actual UL transmit power (303) for the transmission and an indication indicative of whether the maximum UL transmit power (301, 302) used for determining the UPH value (304) is bounded by a maximum power spectral density, PSD, limit (302).

15. An access point, AP, (110) for communication with one or more associated non-AP stations (120), wherein the AP (110) is configured to: receive a data frame and / or a management frame with a frame header from each of the one or more non-AP stations (120), wherein the frame header comprises an uplink, UL, Power Headroom, UPH, value (304) corresponding to the difference between a maximum UL transmit power (301, 302) and an actual UL transmit power (303) for the transmission and an indication indicative of whether the maximum UL transmit power (301, 302) used for determining the UPH value (304) is bounded by a maximum power spectral density, PSD, limit (302).

16. The AP (110) of claim 15, wherein the AP (110) is further configured to: send a trigger frame to the one or more non-AP stations (120), wherein the trigger frame comprises a mode indication of a regular resource unit, RU, transmission mode or a distributed RU, DRU, transmission mode, wherein the mode indication is based on the indication indicative of whether the maximum UL transmit power (301, 302) used for determining the UPH value (304) is bounded by the maximum PSD limit (302); and receive a PPDU from the one or more non-AP stations (120) according to the transmission mode indicated by the mode indication of the trigger frame.

17. The AP (110) of claim 15 or 16, wherein the frame header comprises a UPH control field (310) and wherein the UPH control field (310) comprises the indication indicative of whether the maximum UL transmit power (301, 302) used for determining the UPH value (304) is bounded by the maximum PSD limit (302).

18. The AP (110) of claim 17, wherein the frame header further comprises a PSD Residual Headroom, PRH, value (404) corresponding to the difference between a maximum achievable UL transmit power (301) of the non-AP station (120) and the maximum UL transmit power (301, 302).

19. The AP (110) of claim 18, wherein the frame header comprises a PRH control field (410), wherein the PRH control field (410) comprises the PRH value (404).

20. The AP (110) of claim 19, wherein the PRH control field (410) has a valid value, in case the indication indicates that the maximum UL transmit power (301, 302) used for determining the UPH value (304) is bounded by the maximum PSD limit (302).

21. The AP ( 110) of any one of any one of the preceding claims, wherein the frame header further comprises a DRU Gain Headroom, DGH, value (504) corresponding to the difference between a minimum UL transmit power (501) of the non- AP station ( 120) for achieving a target RS SI value indicated by the AP ( 110) and the maximum UL transmit power (301, 302), when the value of minimum UL transmit power (501) for achieving the target RSSI value indicated by the AP (110) is greater than the maximum UL transmit power value (301, 302).

22. The AP (110) of claim 21, wherein the frame header comprises a DGH control field (510), wherein the DGH control field (510) comprises the DGH value (504).

23. The AP (110) of claims 15 or 16, wherein the frame header further comprises a Negative DRU Headroom, NDH, value corresponding to the difference between the actual UL transmit power (303) for the transmission and the maximum UL transmit power (301, 302), when the DRU transmission mode is applied.

24. The AP (110) of claim 23, wherein the frame header comprises an NDH control field (610), wherein the NDH control field (610) comprises the NDH value.

25. The AP (110) of any one of claims 15 to 24, wherein the AP (110) is configured to send a PSD Limit Info Request Poll trigger frame to the one or more non-AP stations (120), wherein the PSD Limit Info Request Poll trigger frame is indicative of a target RSSI value and request for an information of one or more of the PRH control field (410), the DGH control field (510), and / or the NDH control field (610).

26. The AP (110) of claim 25, wherein, in response to sending the PSD Limit Info Request Poll trigger frame to the one or more non-AP stations (120), the AP (110) is configured to receive from each of the one or more solicited non-AP stations (120) for the indicated target RSSI value the one or more of the PRH control field (410), the DGH control field (510), and / or the NDH control field (610) indicated by the preceding PSD Limit Info Request Poll trigger frame.

27. The AP (110) of claim 26, wherein the AP (110) is configured to receive the one or more of the PRH control field (410), the DGH control field (510), and / or the NDH control field (610) from the non-AP station (120) as part of an Initial Control frame, ICF, an Initial Control Response, ICR, frame or a Control Response frame, CRF.

28. A method (800) for operating an access point, AP, (110) for communication with one or more associated non-AP stations (120), wherein the method (800) comprises: receiving (801) a data frame and / or a management frame with a frame header from the one or more non-AP stations (120), wherein the frame header comprises an uplink, UL, Power Headroom, UPH, value (304) corresponding to the difference between a maximum UL transmit power (301, 302) and an actual UL transmit power (303) for the transmission and an indication indicative of whether the maximum UL transmit power (301, 302) used for determining the UPH value (304) is bounded by a maximum power spectral density, PSD, limit (302).

29. 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 (700) of claim 14 or the method (800) of claim 28 when the program code is executed by the computer or the processor.