CN115280706A

CN115280706A - Peak-to-average power ratio reduction for multi-resource unit allocation in wireless networks

Info

Publication number: CN115280706A
Application number: CN202080098313.9A
Authority: CN
Inventors: 根纳季·特所迪克; 希米·西隆; 奥德·里德里; 多伦·埃兹里; 埃泽尔·梅尔泽
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-03-09
Filing date: 2020-03-09
Publication date: 2022-11-01
Also published as: WO2021180297A1

Abstract

The present disclosure relates to a wireless network, which may be a Wireless Local Area Network (WLAN) according to a WiFi standard, and generally to multi-resource unit (MRU) allocation in the wireless network. Accordingly, embodiments of the present disclosure provide a wireless network device and corresponding method for MRU allocation, respectively. The wireless network device is configured to select a training signal for an MRU, where the MRU includes two or more RUs arranged in a frequency domain, and the training signal includes a training sequence for each RU. Further, for at least one RU, the wireless network device is to apply a subset of phase values to the training sequence for the at least one RU, wherein the subset of phase values is selected for the at least one RU from a set of phase values assigned to the MRU.

Description

Peak-to-average power ratio reduction for multi-resource unit allocation in wireless networks

Technical Field

The present disclosure relates to wireless networks, and generally to Resource Unit (RU) allocation in wireless networks. In particular, the present disclosure relates to Multi Resource Unit (MRU) allocation in a wireless network, which may be a Wireless Local Area Network (WLAN) configured according to WiFi standards and the like. Embodiments of the present disclosure respectively provide a wireless network device and a corresponding method suitable for MRU allocation.

Background

MRU allocation is generally accepted for future implementations in wireless networks (e.g., in next generation WiFi standards). MRU allocation in a wireless network provides a way to achieve more efficient channel utilization. MRU allocation means non-contiguous frequency allocation, i.e. multiple non-contiguous RUs. Since this is a new technology in wireless networks (especially in WiFi standards), the specific implementation of such MRU allocation is rare.

In particular, there is a need to efficiently implement MRU allocation in wireless networks, in particular according to WiFi standards. However, efficient implementation is not straightforward. For example, as shown in the following portions of the present disclosure, simply implementing MRU allocation in such a wireless network can significantly affect the physical properties of the transmitted signals in the wireless network.

Disclosure of Invention

As provided later in the disclosure, embodiments of the present disclosure are based on the following analysis and problems identified by the inventors. Briefly, the inventors have discovered that simple MRU allocation in a wireless network can increase peak-to-average-power-ratio (PAPR), which is an important indicator in wireless network technology.

The 802.11ax standard introduces an Orthogonal Frequency Division Multiple Access (OFDMA) format in which the entire Bandwidth (BW) is divided into blocks, which are defined as RUs. The transmitted signals may be combined by multiple RU allocations, where different RUs may be allocated to different stations (i.e., wireless network devices). Thus, the size of an RU may be defined by a number of frequency tones, which may include 26, 52, 106, 242, 484, or 996 tones. For example, a BW of 20MHz may include 9 RUs of 26 tones, 4 RUs of 52 tones, and so on, as depicted in fig. 1.

Fig. 2 and 3 depict the structure of RU in 40MHz and 80MHz, respectively. The larger BW, including 240MHz and 320MHz in 802.11be, is a repetition of the 80MHz structure. In the following, each RU uses index notation, where the index starts from the left side of the BW (i.e. the leftmost 26RU is the first 26RU, and the rightmost 26RU is the ninth 26 RU).

In 802.11be, MRU allocation is generally foreseen, where more than one RU is allocated to a single station or group of stations (i.e., wireless network devices). This means discontinuous BW allocation (e.g., as shown in fig. 4, where multiple RUs (here at least a first RU and a second RU) are disposed in the frequency domain of one MRU).

Currently, the 802.11be standard foresees two types of MRU allocation:

only large RUs, i.e., greater than or equal to 20MHz (RU 242, RU484, RU996, etc.), may be combined into the MRU.

Only small RUs (RU 26, RU52, RU 106) can be combined to the MRU within the 20MHz boundary.

The present standard does not currently support the combination of small and large RUs.

The transmitted signal typically includes one or more training sequences (e.g., short Training Field (STF), long Training Field (LTF), high efficiency STF (HE-STF), or high efficiency LTF (HE-LTF)) preceding the data portion, which support the receiving side in synchronizing on the transmitted signal and performing wireless channel estimation. Typically, these training sequences are designed for low PAPR (specifically, lower PAPR than the data portion of the transmitted signal) to ensure high accuracy of channel estimation. However, in older WiFi standard versions (e.g., in 802.11 a/n/ac/ax), the design of the training sequence assumes that a continuous bandwidth is allocated for transmission (downlink, DL) and/or Uplink (UL)). Thus, PAPR is optimized in this assumption at best. This will result in a higher PAPR (in particular, a PAPR higher than the continuous BW) if the current training sequence is to be reused for MRU allocation in the wireless network.

Fig. 5 shows an exemplary comparison of PAPR of continuous BW with PAPR of MRU allocation, in particular for MRU consisting of large RUs and MRU consisting of small RUs, respectively. HE-LTF sequences defined in the 802.11ax standard were used. This HE-LTF applies to each RU because it is defined for single RU transmission. The x-axis in FIG. 5 represents different combinations of RUs, with the indices aligned with the 802.11be definition (i.e., the first number represents the larger RU index and the second number represents the smaller RU index). It can be seen that the PAPR of the HE-LTF increases by 1.5dB to 2dB in the case of large RU combination (see fig. 5 (a)), and increases by 1.5dB to 3dB in the case of small RU combination (see fig. 5 (b)).

As described above, the PAPR of the training sequence is designed to be lower than the PAPR of the data portion. Therefore, the influence of MRU on PAPR of the data part was also examined. Fig. 6 shows in this regard the PAPR of the data portion (where, for example, the data in the data portion may be random and thus is represented here illustratively by a Cumulative Distribution Function (CDF)). It can be seen that for large RUs (see fig. 6 (a)) and small RUs (see fig. 6 (b)), the PAPR of the data part increases by 0.5dB to 1dB, which is smaller than the PAPR of the HE-LTF. Therefore, it can be appreciated that there is a problem with the design of reusing the current training sequence (e.g., HE-LTF sequence), and therefore, in the case of MRU allocation, a new or updated training sequence should be considered to reduce PAPR.

Fig. 7 shows a theoretical explanation of the PAPR problem described above. In the case of an MRU, the time domain signal may be represented as a combination of multiple domain signals, each domain signal being generated by a single RU (here, a first RU and a second RU). The effect on PAPR that MRU allocation produces is related to the combined peak of these transmitted signals, where the sum of two or more peaks produces a higher total peak in some samples.

Typically, the PAPR problem has been addressed in earlier versions of the WiFi standard, e.g., the training sequence was designed to minimize the PAPR metric. Furthermore, wiFi introduces constant phase rotation, which is also believed to reduce PAPR in case of large BW. Fig. 8 shows such a phase rotation, as defined by the 80MHz BW in 802.11 ac.

Applying constant phase rotation can reduce PAPR and is defined for BW of 40/80/160 MHz. Extensions to BW of 240MHz and 320MHz of this method are also provided and different choices of constant phase rotation are given as examples.

However, the main problem with this approach (including the extensions for 240MHz and 320 MHz) is that a constant phase rotation is designed for allocating the entire BW:

constant phase results in incoherent combining of multiple peaks, but does not change the position of the peak in the time domain.

Different MRUs may need to apply different phases to the same tone part to optimize PAPR. For example, the combination of the first 20MHz and the third 20MHz may require a different phase value than the combination of the first 20MHz and the fourth 20 MHz. Therefore, PAPR optimization cannot be guaranteed by constant phase rotation applied to the same part of BW.

Another problem is that this approach can only be applied to PAPR optimization for large RU combinations, and in case of MRUs for small RU combinations, an efficient implementation is also needed to optimize PAPR.

In view of the above problems and disadvantages, embodiments of the present disclosure aim to provide a solution to the problem of MRU allocation affecting PAPR. In particular, it is an object to provide a wireless network device and a corresponding method, which are capable of allocating MRUs in a wireless network, in particular in a wireless network according to the WiFi standard, without any impact (or at least a significant reduction of the impact) on PAPR.

This object is achieved by the embodiments of the present disclosure described in the appended independent claims. Advantageous implementations of embodiments of the present disclosure are further defined in the dependent claims.

Theoretical considerations underlying embodiments of the present disclosure are illustrated in fig. 9. In principle, if the following two points are implemented: the chance of peak combining to higher values can be reduced by the variation of the position of the peaks in the time domain and by avoiding coherent combining of the signals. This may be achieved by applying a cyclic shift to the OFDM symbols in the time domain (see fig. 9) and/or by adding a phase offset. As can be understood from fig. 9, the peak positions can be shifted, thereby preventing the combination of high peaks. Equivalent to cyclic shift in the frequency domain is to multiply the frequency tones of the RU by phase values, e.g., by linear phase and phase offset. The phase offset may actually be the initial value of the linear phase.

A first aspect of the present disclosure provides a wireless network device for MRU allocation, the wireless network device being configured to: selecting a first training signal for a first MRU, wherein the first MRU comprises two or more RUs disposed in the frequency domain, the first training signal comprising a training sequence for each RU of the first MRU; for at least one RU of the first MRU, a subset of first phase values of a training sequence for the at least one RU of the first MRU is applied, wherein the subset of first phase values is selected for the at least one RU of the first MRU from a set of first phase values assigned to the first MRU.

In particular, the wireless network device of the first aspect may further provide the thus modified training signal (i.e. the signal comprising the training sequence modified by applying the first subset of phase values) to the receiving device. The wireless network device may also provide data after transmission of the training signal, in particular, the data is distributed to the receiving device on the first MRU. Advantageously, applying the subset of first phase values to the training sequence of one or more RUs of the first MRU may significantly reduce PAPR-this is in line with the above considerations. It should be noted that if such an application is made to more than one RU of the first MRU, each RU may be assigned a different subset of the first phase values. The "subset of first phase values" may be any set of phase values included in the "set of first phase values".

Further, each MRU may be assigned a different set of phase values. For example, a first MRU may be assigned a first set of phase values and a second MRU may be assigned a second set of phase values. Further, for each RU of a particular MRU, a particular subset of phase values may be selected from the set of phase values assigned to that particular MRU. For example, the set or subset of phase values may comprise { -pi, -pi/2,0, pi/2, pi }, i.e., a plurality of phase values.

In one implementation form of the first aspect, the wireless network device is further configured to: selecting a second training signal for a second MRU, wherein the second MRU includes two or more RUs disposed in the frequency domain, and wherein the second training signal includes a training sequence for each RU of the second MRU; for at least one RU of the second MRU, applying a second subset of phase values to the training sequence for the at least one RU of the second MRU, wherein the second subset of phase values is selected for the at least one RU of the second MRU from the set of second phase values assigned to the second MRU.

Specifically, the first MRU and the second MRU are different MRUs. Thus, different MRUs may assign different sets of phase values. These different sets of phase values may include different subsets of phase values, but may also have a particular subset of phase values in common. This implementation may reduce PAPR more efficiently. It should be noted that if such an application is made to more than one RU of the second MRU, each RU may be assigned a different subset of second phase values. The "second subset of phase values" may be any set of phase values included in the "second set of phase values".

In one implementation of the first aspect, the subset of first phase values consists of first linear phases and first phase offsets, and the set of first phase values consists of a set of first linear phases and a set of first phase offsets; and/or the second subset of phase values is comprised of a second set of linear phases and a second set of phase offsets, the second set of phase values is comprised of a second set of linear phases and a second set of phase offsets.

Any linear phase may be or include a set of phase values with a constant gap between them. Applying a linear phase to a given RU may mean multiplying the frequency tone of the given RU by the phase value of the applied linear phase. For example, the first tone of a given RU may be multiplied by the phase value 0, the second tone of the given RU may be multiplied by the phase value pi/N, the third tone of the given RU may be multiplied by the phase value 2x pi/N, and so on. Thus, a linear phase may also be defined as a sequence of phase values.

For example, if K is expressed as an index of frequency tones within the ith RU of a particular MRU (e.g., first and/or second MRU), where RU includes K tones, and where x _k Is the value of the training sequence defined for the k-th tone, the shifted signal for the ith RU can be given by:

where M is the number of RUs included in a particular MRU.

The implementation mode can also comprise:

for any training sequence, a specific linear phase and a specific phase offset can be defined, which can be applied to the tones of one or more or each RU comprised by a specific MRU.

Linear phase and phase offset may be defined to optimize PAPR for each MRU, while in case of different MRUs, different subsets of phase values may be applied to the same RU.

Multiple RUs or each RU within a particular MRU may be multiplied by different linear phases and/or different phase offsets.

The values of the linear phase and the phase offset may be known in advance for the transmitting side (e.g. at the wireless network device) and the receiving side, in particular for each MRU. However, the actual implementation design of the transmitting and receiving devices may vary.

In one implementation of the first aspect, the first MRU and the second MRU have one or more RUs in common; alternatively, the first MRU and the second MRU do not have a common RU.

In one implementation of the first aspect, the first set of linear phases includes one or more linear phases that are not included in the second set of linear phases; and/or the first set of phase offsets includes one or more phase offsets that are not included in the second set of phase offsets.

In an implementation form of the first aspect, the first set of linear phases and/or the second set of linear phases is comprised in [ -pi, pi [ -pi [, ]]A linear phase defined within the range of (1), wherein the granularity is a linear phase value

n is an integer; and/or the first set of phase offsets and/or the second set of phase offsets are comprised in [ - π, π]Wherein the granularity is the phase offset

m is an integer.

In one implementation manner of the first aspect, the wireless network device is further configured to: for each RU of the first MRU and/or the second MRU, the first and/or second subset of phase values is applied to the training sequences of the RUs of the first MRU and/or the second MRU.

In this way, the PAPR can be reduced more efficiently.

In one implementation of the first aspect, the first and/or second subset of phase values is applied to the training sequence of the at least one RU of the first MRU and/or the second MRU by multiplying the value of the training sequence by the value in the first and/or second subset of phase values.

In one implementation of the first aspect, the values of the first and/or second linear phases and the first and/or second phase offsets are defined by a single set of values; or the values of the first and/or second linear phase and the first and/or second phase offset are defined by a first set of values and a second set of values, wherein the first set of values defines a constant phase offset value and the second set of values defines the values of the first and/or second linear phase, wherein a constant phase offset is added to each value of the first and/or second linear phase, respectively.

In one implementation of the first aspect, different first and/or second subsets of phase values are selected for at least two RUs of the first MRU and/or the second MRU.

In one implementation of the first aspect, a different subset of the first and/or second phase values is selected for each RU of the first MRU and/or the second MRU.

In one implementation of the first aspect, a first and/or second subset of phase values of zero is selected for at least one RU of the first MRU and/or the second MRU.

In one implementation of the first aspect, the first and/or second subset of phase values is selected for at least one RU of the first MRU and/or the second MRU to minimize PAPR.

Further, the first and/or second set of phase values assigned to the first and/or second MRU may be selected or created to minimize PAPR.

In one implementation of the first aspect, each RU includes a plurality of frequency tones, each value of the first and/or second subset of phase values selected for at least one RU of the first MRU and/or the second MRU being associated with one of the frequency tones of the at least one RU of the first MRU and/or the second MRU.

In one implementation form of the first aspect, the wireless network device is further configured to: for at least one RU of the first MRU and/or the second MRU, applying only selected values of the first and/or second subset of phase values selected for the at least one RU of the first MRU and/or the second MRU to the training sequence of the at least one RU of the first MRU and/or the second MRU, wherein the selected values are values of the first and/or second subset of phase values associated with each frequency tone, each second frequency tone, or each fourth frequency tone of the at least one RU of the first MRU and/or the second MRU.

Thus, the wireless network device of the first aspect is capable of using 1X, 2X and/or 4X formats.

In one implementation of the first aspect, the first and/or second subset of phase values is selected for at least one RU of the first MRU and/or the second MRU depending on whether a selected value is associated with each frequency tone, each second frequency tone, or each fourth frequency tone.

In one implementation of the first aspect, the first MRU and/or the second MRU comprises only larger RUs, each RU having a bandwidth above 20MHz, or the first MRU and/or the second MRU comprises only smaller RUs, each RU having a bandwidth below 20 MHz.

Thus, the wireless network device of the first aspect may use all different types of MRUs.

In an implementation form of the first aspect, the training sequence of the first training signal and/or the second training signal comprises at least one of: a legacy LTF (L-LTF) sequence or a legacy STF (L-STF) sequence or an extra high throughput STF (EHT-STF) sequence or an EHT-LTF sequence.

In one implementation form of the first aspect, the wireless network device is further configured to: providing an indication of the first and/or second subset of phase values for multiplication by a training sequence of at least one RU of the first MRU and/or the second MRU; or providing an indication of a first and/or second subset of phase values of a training sequence for at least one RU multiplied by the first MRU and/or the second MRU.

In particular, the indication may be provided to the receiving side. Or, for example, if the phase value is always applied and known by both the transmitting side (wireless network device) and the receiving side, no indication may be provided. The receiving side may be preconfigured with relevant information about the first and/or second subset of phase values.

A second aspect of the present disclosure provides a method for Multiple Resource Unit (MRU) allocation in a wireless network, the method comprising: selecting a first training signal for a first MRU, wherein the first MRU comprises two or more RUs arranged in the frequency domain, the first training signal comprising a training sequence for each RU of the first MRU; for at least one RU of the first MRU, a subset of first phase values of a training sequence of the at least one RU of the first MRU is applied, wherein the subset of first phase values is selected for the at least one RU of the first MRU from a set of first phase values assigned to the first MRU.

In one implementation form of the second aspect, the method further comprises: selecting a second training signal for a second MRU, wherein the second MRU includes two or more RUs disposed in the frequency domain, and wherein the second training signal includes a training sequence for each RU of the second MRU; for at least one RU of the second MRU, applying a second subset of phase values to the training sequence for the at least one RU of the second MRU, wherein the second subset of phase values is selected for the at least one RU of the second MRU from the set of second phase values assigned to the second MRU.

In one implementation of the second aspect, the subset of first phase values consists of first linear phases and first phase offsets, and the set of first phase values consists of a set of first linear phases and a set of first phase offsets; and/or the second subset of phase values is comprised of a second set of linear phases and a second set of phase offsets, the second set of phase values is comprised of a second set of linear phases and a second set of phase offsets.

In one implementation of the second aspect, the first MRU and the second MRU have one or more RUs in common; alternatively, the first MRU and the second MRU do not have a common RU.

In one implementation of the second aspect, the first set of linear phases includes one or more linear phases that are not included in the second set of linear phases; and/or the first set of phase offsets includes one or more phase offsets that are not included in the second set of phase offsets.

In an implementation form of the second aspect, the first set of linear phases and/or the second set of linear phases are comprised in [ -pi, pi [ -pi [, ]]A linear phase defined within the range of (1), wherein the granularity is a linear phase value

n is an integer; and/or the first set of phase offsets and/or the second set of phase offsets are comprised in [ -pi, pi [ -pi [, ]]Wherein the granularity is the phase offset

m is an integer.

In one implementation form of the second aspect, the method further comprises: for each RU of the first MRU and/or the second MRU, the first and/or second subset of phase values is applied to the training sequences of the RUs of the first MRU and/or the second MRU.

In one implementation of the second aspect, the first and/or second subset of phase values is applied to the training sequence of at least one RU of the first MRU and/or the second MRU by multiplying the value of the training sequence by the value in the first and/or second subset of phase values.

In one implementation of the second aspect, the values of the first and/or second linear phases and the first and/or second phase offsets are defined by a single set of values; or the values of the first and/or second linear phase and the first and/or second phase offset are defined by a first set of values and a second set of values, wherein the first set of values defines a constant phase offset value and the second set of values defines the values of the first and/or second linear phase, wherein a constant phase offset is added to each value of the first and/or second linear phase, respectively.

In one implementation of the second aspect, different first and/or second subsets of phase values are selected for at least two RUs of the first MRU and/or the second MRU.

In one implementation of the second aspect, a different subset of first and/or second phase values is selected for each RU of the first MRU and/or the second MRU.

In one implementation of the second aspect, the first and/or second subset of phase values that are zero are selected for at least one RU of the first MRU and/or the second MRU.

In one implementation of the second aspect, the first and/or second subset of phase values is selected for at least one RU of the first MRU and/or the second MRU to minimize PAPR.

In one implementation of the second aspect, each RU includes a plurality of frequency tones, each value of the first and/or second subset of phase values selected for the at least one RU of the first MRU and/or the second MRU being associated with one of the frequency tones of the at least one RU of the first MRU and/or the second MRU.

In one implementation form of the second aspect, the method further comprises: for at least one RU of the first MRU and/or the second MRU, applying only selected values of the first and/or second subset of phase values selected for the at least one RU of the first MRU and/or the second MRU to the training sequence of the at least one RU of the first MRU and/or the second MRU, wherein the selected values are values of the first and/or second subset of phase values associated with each frequency tone, each second frequency tone, or each fourth frequency tone of the at least one RU of the first MRU and/or the second MRU.

In one implementation of the second aspect, the first and/or second subset of phase values is selected for at least one RU of the first MRU and/or the second MRU depending on whether a selected value is associated with each frequency tone, each second frequency tone, or each fourth frequency tone.

In one implementation of the second aspect, the first MRU and/or the second MRU includes only larger RUs, each having a bandwidth above 20MHz, or the first MRU and/or the second MRU includes only smaller RUs, each having a bandwidth below 20 MHz.

In an implementation form of the second aspect, the training sequence of the first training signal and/or the second training signal comprises at least one of: a legacy LTF (L-LTF) sequence or a legacy STF (L-STF) sequence or an extremely high throughput STF (EHT-STF) sequence or an EHT-LTF sequence.

In one implementation form of the second aspect, the method further comprises: providing an indication of the first and/or second subset of phase values for multiplication by a training sequence of at least one RU of the first MRU and/or the second MRU; or providing an indication of a first and/or second subset of phase values of a training sequence for at least one RU multiplied by the first MRU and/or the second MRU.

A third aspect of the disclosure provides a computer program comprising program code for performing a method according to the second aspect or any implementation thereof when the program code is executed on a computer.

A fourth aspect of the present disclosure provides a non-transitory storage medium storing executable program code that, when executed by a processor, performs a method according to the third aspect or any of its implementations.

It should be noted that all devices, elements, units and modules described in the present application may be implemented by software or hardware elements or any type of combination thereof. All steps performed by the various entities described in the present application and the functions described to be performed by the various entities are intended to indicate that the respective entities are for performing the respective steps and functions. Although in the following description of specific embodiments specific functions or steps performed by external entities are not reflected in the description of specific detailed elements of the entity performing the specific steps or functions, it should be clear to a skilled person that these methods and functions may be implemented by corresponding hardware or software elements or any combination thereof.

Drawings

The following description of specific embodiments, taken in conjunction with the accompanying drawings, set forth above aspects and implementations.

Fig. 1 shows the RU position at 20 MHz.

Fig. 2 shows the RU position at 40 MHz.

Fig. 3 shows the RU position at 80 MHz.

Fig. 4 shows an MRU allocation example.

Fig. 5 shows a comparison of PAPR over HE-LTF for MRU allocation.

Fig. 6 shows a comparison of PAPR over data for MRU allocation.

Fig. 7 shows the high PAPR theory in the case of MRU allocation.

Fig. 8 shows an example of phase rotation defined in the 11ac WiFi standard.

Fig. 9 shows a time domain signal with a cyclic shift.

Fig. 10 illustrates a wireless network device according to an embodiment of the disclosure.

Fig. 11 illustrates a wireless network device applying linear phase and phase offset according to an embodiment of the present disclosure.

Fig. 12 illustrates a wireless network device applying linear phase and phase offset according to MRU according to an embodiment of the present disclosure.

Fig. 13 illustrates a wireless network device applying relatively linear phase and phase offsets in accordance with an embodiment of the disclosure.

Fig. 14 shows PAPR reduction in the case of an embodiment of the present disclosure.

Fig. 15 shows PAPR in a specific case.

Fig. 16 illustrates a method according to an embodiment of the present disclosure.

Detailed Description

Fig. 10 illustrates a wireless network device 100 according to an embodiment of the disclosure. The wireless network device 100 is used for MRU allocation in a wireless network, in particular in a WLAN, more particularly in a wireless network configured according to the WiFi standard. Thus, the wireless network device 100 may be configured according to and conform to a WiFi standard. Wireless network device 100 may be a station or terminal and may communicate with one or more other wireless network devices (stations or terminals) in a wireless network.

Wireless network device 100 is configured to select a first training signal 101 for a first MRU 102. In general, the wireless network device 100 may be used to select a training signal 101 for each MRU. The first MRU 102 comprises two or more RUs 103 arranged in the frequency domain, i.e. the two or more RUs 103 are separated/far apart in the frequency direction, e.g. they occupy different sets of subcarriers (e.g. in case of OFDM). The first training signal 101 comprises a training sequence 104 for each RU 103 of the first MRU 102 (two RUs 103 and two training sequences 104 are exemplarily shown here).

The wireless network device 100 may: for at least one RU 103 of the first MRU 102 (specifically, for one or more RUs 103 of the first MRU 102, or each RU 103), the first subset of phase values 105 is applied. For example, for a given RU 103, a first subset of phase values 105 may be applied to the given RU103, and a training sequence 104. In fig. 1, illustratively, a first subset of phase values 105 (denoted as θ) ₁ (1.... N)) is applied to a first RU 103 of a first MRU 102, and a different subset 105 of first phase values (denoted as θ) ₂ (1.... N)) is applied to second RU 103 of first MRU 102.

Any first subset of phase values 105 may include one or more phase values. A first subset of phase values 105 is selected for at least one RU 103 of the first MRU 102. Specifically, the subset of first phase values 105 is selected from a set of first phase values assigned to the first MRU 102. It should be noted that the set of phase values may include one or more subsets of phase values, and/or may include one or more phase values.

A different subset of first phase values 105 may be applied to multiple or each RU 103 of the first MRU 102. Applying the one or more first phase value subsets 105 to the one or more training sequences 104 of the one or more RUs 103 of the first MRU 102 results in a modified training signal 106 that may be provided/transmitted by the wireless network device 100.

The wireless network device 100 may include a processor or processing circuitry (not shown) for performing, carrying out, or initiating the various operations of the wireless network device 100 described herein. The processing circuitry may comprise hardware and/or the processing circuitry may be controlled by software. The hardware may include analog circuitry or digital circuitry, or both analog and digital circuitry. The digital circuit may include an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a Digital Signal Processor (DSP), or a multi-purpose processor.

The wireless network device 100 may also include memory circuitry that stores one or more instructions that may be executed by the processor or processing circuitry, particularly under control of software. For example, the memory circuit may include a non-transitory storage medium storing executable software code that, when executed by the processor or processing circuit, causes the wireless network device 100 to perform various operations.

In one embodiment, the processing circuit includes one or more processors and non-transitory memory coupled to the one or more processors. The non-transitory memory may carry executable program code that, when executed by the one or more processors, causes the wireless network device 100 to perform, carry out, or initiate the operations or methods described herein.

Fig. 11 illustrates a wireless network device 100 according to an embodiment of the disclosure, which is based on the embodiment illustrated in fig. 10. In this embodiment of fig. 11, the subset of first phase values 105 consists of first linear phases and first phase offsets, respectively, and thus the set of first phase values consists of a set of first linear phases and a set of first phase offsets. That is, the first linear phase and the first phase offset may be applied to one or more or each RU 103 of first MRU 102 as first subset of phase values 105. A different first linear phase and a different first phase offset may be applied to each given RU 103 of first MRU 102. For example, a different first linear phase and first phase offset may be independently applied to each of the plurality of selected RUs 103 included by first MRU 102. Fig. 11 exemplarily shows that two different first linear phases and first phase offsets are applied to the training sequence 104 of the first RU 103 and the training sequence 104 of the second RU 103 of the first MRU 102, respectively. It should be noted that the "first linear phase" is any linear phase included in the "first linear phase set". Similarly, a "first phase offset" is any phase offset included in a "first set of phase offsets".

First, a first training signal 101 is selected (e.g., based on BW, a particular first MRU, etc.), and then the values of the training signal 101 (specifically the training sequences 104 for the different RUs 103) are multiplied by the values of the first linear phase with the first phase offset, as they may be predefined for each RU 103 within the MRU 102.

Fig. 12 shows a wireless network device 100 according to an embodiment, which is based on the embodiments of fig. 10 and 11. In particular, FIG. 12 shows that different sets of linear phases and different sets of phase offsets may be applied to RUs 103/203 of different MRUs 102/202, and in particular to each different MRU used. Accordingly, wireless network device 100 may also be used to select a second training signal 201 for a second MRU 202 (different from first MRU 102), where second MRU 202 includes two or more RUs 203 (RUs 103/203 may be the same or different) disposed in the frequency domain, i.e., they are separated in the frequency direction, e.g., they occupy different sets of subcarriers (e.g., in the case of OFDM). The second training signal 201 includes a training sequence 204 for each RU 203 of the second MRU 202. Further, the wireless network device 100 is configured to: for at least one RU 203 of the second MRU 202 (i.e., for one or more RUs 203, or each RU 203, of the second MRU 202), a particular second linear phase and second phase offset (or generally a second subset of phase values 205) are applied to the training sequence 201 of the at least one RU 203. The second linear phase may be selected from a second set of linear phases, and the second phase offset may be selected from a second set of phase offsets for at least one RU 203 of the second MRU 203. Thus, a second set of linear phases and a second set of phase offsets may be assigned to second MRU 202. It should be noted that the "second linear phase" is any linear phase included in the "second linear phase set". The "second phase offset" is any phase offset included in the "second set of phase offsets".

For example, different MRUs (types) 102, 202 including

RUs

103, 203 may optimize PAPR using different (first/second) linear phases and phase offsets. Thus, when the

same RU

103 or 203 is allocated within two

different MRUs

102, 202, different linear phases and phase offsets may be applied. Fig. 12 shows an example in which, in a first case, MRU 102 comprises a first RU and a second RU, and in a second case, different MRUs 202 comprise (identical) first and third RUs. In both cases, the linear first/second phase and first/second phase offsets of training sequence 104 applied to the first RU in first MRU 102 and second MRU 202, respectively, are shown to be different.

Further, wireless network device 100 may work with all types of

MRUs

102, 202. For example, first MRU 102 and/or second MRU 103 may include

large RUs

103, 203 only for any BW greater than 20MHz, or may include

small RUs

103, 203 only for a BW of 20 MHz.

The wireless network device 100 may also work with training signals 101, 201 of different formats. For example, the 802.11be standard employs training sequence designs with different carrier spacings, where the same BW may be sampled with different numbers of frequency tones. Thus, the maximum number of frequency tones in the training signal format is represented by 4X. If every second tone is used, the format is represented by 2X. If only every fourth tone is used, the format is represented by 1X. The linear phase and phase offset applicable to different formats can be designed in two ways:

for the 2X and 1X formats, a subset of the 4X format may be applied (i.e., meaning, for example, that every second and fourth value of the first and/or second linear phase, respectively, may be used), and the phase offset is the same as the 4X format.

Different linear phases and phase offsets can be designed for each format.

The two approaches described above can also be combined, while a linear phase or a phase offset can be designed specifically for each format.

The wireless network device 100 may also work with at least the following training signals 101/201 or training sequences 104/204: L-LTF; L-STF; EHT-STF; and/or EHT-LTF.

Furthermore, the first/second linear phase and phase offsets may be applied as absolute or relative linear phase and phase offsets. As described above in theoretical considerations, embodiments of the present disclosure may be considered to implement cyclic shifts in the time domain, with the goal of separating the peaks of the different signals associated with

RUs

103, 203 within

MRUs

102, 202. The offset in the time domain may be considered an absolute value, where each signal is shifted by a number of time samples greater than zero (as depicted in fig. 11), or a relative offset may be considered, where one signal is not shifted (zero linear phase) and all other signals are shifted by a number of time samples greater than zero (as depicted in fig. 13). The same applies to phase shifting. Any

RU

102, 202 may be selected as an

RU

102, 202 with zero linear phase and/or zero phase offset.

Any first/second linear phase and first/second phase offset may be defined in two different ways:

defined as a single set of values

Defined as two sets of values

Where w defines a constant phase offset applied to all tones within the

RU

103, 203, v _k A linear phase is defined that is applied to each tone within the

MRU

102, 202.

The values of the first/second linear phases and the first/second phase offsets may be predefined, and for each

RU

103, 203 within a

particular MRU

102, 202, the value may be selected from a predefined list:

any linear phase can be defined in the range of θ ∈ { - π, π } where the granularity is

Wherein, delta E is {1,2 _Lin }。N _Lin The maximum possible granularity of the linear phase values may be defined.

Any phase shift can be in

Is defined within the range of (1), wherein the particle size is

Wherein, delta E is {1,2 _Offset }。N _Offset The maximum possible granularity of the phase offset values may be defined.

Further, the wireless network device 100 may provide an indication of the applied linear phase and phase offset. For example, to support successful detection of the transmitted signal by the receiving side, several indication methods may be defined for use by the transmitting side (wireless network device 100):

no indication: in this case, the linear phase and the phase offset are always applied to a given MRU (transmission), and specific values are known in advance to the transmitting side (radio network device 100) and the receiving side.

Indication using linear phase and phase offset: in this case, the transmitting side (wireless network device 100) may decide to apply or not apply the first/second linear phases and the phase offsets, and should indicate this in the transmission signal. The values of the first/second linear phases and the phase offsets may be known in advance.

Using an indication of linear phase and phase offset with a specific value: in this case, the transmitting device (wireless network device 100) may decide which values to use for the current transmission. Thus, the indication may include an indication of the use of linear phase and phase offset, as well as an indication of the particular value selected for the current transmission.

In the following, the wireless network device 100 and corresponding method are demonstrated to achieve the desired goals of PAPR reduction. Therefore, the focus is on the difference between PAPR reduction on the training sequence 104 and PAPR reduction on the data portion.

Fig. 14 shows an example of PAPR reduction on the training sequence 104 that may be achieved in different cases of the

MRUs

102, 202. It can be seen that in most cases, the PAPR reduction is reduced to a value (0.5 dB to 1 dB) comparable to the PAPR reduction of the data part.

Fig. 15 summarizes PAPR values for the particular case currently discussed in the 802.11be standard.

Fig. 16 shows a method 300 according to an embodiment of the disclosure. The method 300 may be performed by the wireless network device 100 described above. The method 300 is applicable to MRU allocation in a wireless network, such as in a WLAN. The method 300 comprises step 301: a first training signal 101 is selected for a first MRU 102, wherein the first MRU 102 includes two or more RUs 103 disposed in the frequency domain, and wherein the first training signal 101 includes a training sequence 104 for each RU 103 of the first MRU 102. Further, at step 302, for at least one RU 103 of the first MRU 102 (in particular for one or more or each RU 103 of the first MRU 102), a first subset of phase values is applied to the training sequence 104 of the at least one RU 103 of the first MRU 103, wherein the first subset of phase values is selected for the at least one RU 103 of the first MRU 102 from the first set of phase values assigned to the first MRU 102.

The embodiments described in this disclosure are not limited to a particular training signal 101, 201. However, they support the reuse of existing sequences defined by the old WiFi standard. Further, embodiments of the present disclosure may be applied to 1x, 2x, and 4x signals. The 1x and 2x linear phase values may be treated as a subset of 4x (no additional memory required). With the embodiments of the present disclosure, the impact of MRU allocation on PAPR can be minimized. The ratio between the PAPR on the

training signal

101, 202 and the PAPR on the data portion of the transmitted signal may only be affected by 0.5 dB. Furthermore, the implementation of the phase value subset (e.g. by linear phase and phase offset), i.e. constant phase, is simple and does not require high computational complexity.

The present disclosure has been described in connection with various embodiments and implementations of the disclosure as examples. However, other variations can be understood and effected by those skilled in the art in practicing the claimed embodiments of the disclosure, from a study of the drawings, the disclosure, and the independent claims. In the claims as well as in the description, the word "comprising" does not exclude other elements or steps, and "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Hereinafter, examples are given that are helpful in understanding the present disclosure.

Examples of linear phase effective values

Theta is belonged to { -pi, pi }, wherein the granularity is

I.e. a total of 129 values

Example of valid values for phase offset

Wherein the particle size is

I.e. a total of 9 values

Linear phase effective value example for a combined MRU of two 26 RUs at 20MHz BW

An example of linear phase and phase offsets that result in PAPR reduction relative to the linear phase and phase offset effective values given in the example above is given below.

Linear phase effective value example for two 52RU combined MRUs at 20MHz BW

Linear phase effective value example for a combined MRU of 26RU and 52RU at 20MHz BW

Linear phase effective value example for a combined MRU of 26RU and 106RU at 20MHz BW

Linear phase effective value example for combined MRU of 242RU and 484RU under 80MHz BW

Linear phase effective value example for a combined MRU of 484RU and 996RU at 160MHz BW

Linear phase effective value example for combined MRUs of 242RU, 484RU, and 996RU under 160MHz BW

Linear phase effective value example for a combined MRU of three 996 RUs at 320MHz BW

Linear phase effective value example for 484RU and Combined MRU of two 996 RUs at 240MHz BW

Claims

1. A wireless network device (100) for multi-resource unit, MRU, allocation, the wireless network device (100) being configured to:

selecting a first training signal (101) for a first MRU (102),

wherein the first MRU (102) comprises two or more resource units RUs (103) arranged in the frequency domain,

wherein the first training signal (101) comprises a training sequence (104) for each RU (103) of the first MRU (102);

for at least one RU (103) of the first MRU (102), applying a first subset of phase values (105) to the training sequence (104) of the at least one RU (103) of the first MRU (102),

wherein the first subset of phase values (105) is selected for the at least one RU (103) of the first MRU (102) from a first set of phase values assigned to the first MRU (102).

2. The wireless network device (100) of claim 1, further configured to:

selecting a second training signal (201) for a second MRU (202),

wherein the second MRU (202) comprises two or more RUs (203) arranged in the frequency domain,

wherein the second training signal (201) comprises a training sequence (204) for each RU (203) of the second MRU (202);

for at least one RU (203) of the second MRU (202), applying a second subset of phase values (205) to the training sequence (204) of the at least one RU (203) of the second MRU (202),

wherein the second subset of phase values (205) is selected for the at least one RU (203) of the second MRU (202) from a second set of phase values assigned to the second MRU (202).

3. The wireless network device (100) according to claim 1 or 2, wherein:

the first subset of phase values (105) consists of a first set of linear phases and first phase offsets, the first set of phase values consists of a first set of linear phases and a first set of phase offsets; and/or

The second subset of phase values (205) is comprised of a second set of linear phases and a second set of phase offsets, the second set of phase values is comprised of a second set of linear phases and a second set of phase offsets.

4. The wireless network device (100) according to any one of claims 1 to 3, wherein:

the first MRU (102) and the second MRU (202) have one or more RUs (103, 203) in common; or

The first MRU (102) and the second MRU (202) do not have a common RU (103, 203).

5. The wireless network device (100) according to claim 3 or any one of claims 3 and 4, wherein:

the first set of linear phases includes one or more linear phases that are not included in the second set of linear phases; and/or

The first set of phase offsets includes one or more phase offsets that are not included in the second set of phase offsets.

6. The wireless network device (100) according to any one of claims 1 to 5, when according to claim 3, wherein:

the first and/or second set of linear phases are comprised in [ - π, π]Wherein the granularity is the linear phase value

n is an integer; and/or

The first set of phase offsets and/or the second set of phase offsets are comprised in [ -pi, pi [ -pi [ ]]Wherein the granularity is the phase offset

m is an integer.

7. The wireless network device (100) of any of claims 1 to 6, configured to:

for each RU (103, 203) of the first MRU (102) and/or the second MRU (202), applying the first and/or second subset of phase values (105, 205) to the training sequence (104, 204) of the RU (103, 203) of the first MRU (102) and/or the second MRU (202).

8. The wireless network device (100) according to any one of claims 1 to 7, wherein:

applying the first and/or second subset of phase values (105, 205) to the training sequence (104, 204) of the at least one RU (103, 203) of the first MRU (102) and/or the second MRU (202) by multiplying the values of the training sequence (104, 204) by the values in the first and/or second subset of phase values (105, 205).

9. The wireless network device (100) according to claim 8, when according to claim 3, wherein:

the values of the first and/or second linear phases and the first and/or second phase offsets are defined by a single set of values; or

The values of the first and/or second linear phase and the first and/or second phase offset are defined by a first set of values and a second set of values, wherein the first set of values defines a constant phase offset value and the second set of values defines values of the first and/or second linear phase, wherein the constant phase offset is added to each value of the first and/or second linear phase, respectively.

10. The wireless network device (100) according to any one of claims 1 to 9, wherein:

selecting different first and/or second subsets of phase values (105, 205) for at least two RUs (103, 203) of the first MRU (102) and/or the second MRU (202).

11. The wireless network device (100) of any one of claims 1 to 10, wherein:

selecting a different first and/or second subset of phase values (105, 205) for each RU (103, 203) of the first MRU (102) and/or the second MRU (202).

12. The wireless network device (100) of any one of claims 1 to 11, wherein:

selecting a first and/or second subset of phase values (105, 205) of zero for at least one RU (103, 203) of the first MRU (102) and/or the second MRU (202).

13. The wireless network device (100) according to any one of claims 1 to 12, wherein:

selecting the first and/or second subset of phase values (105, 205) for the at least one RU (103, 203) of the first MRU (102) and/or the second MRU (202) to minimize a Peak to average Power ratio, PAPR.

14. The wireless network device (100) of any one of claims 1 to 13, wherein:

each RU (103, 203) includes a plurality of frequency tones;

each value of the first and/or second subset of phase values (105, 205) selected for the at least one RU (103, 203) of the first MRU (102) and/or the second MRU (202) is associated with one of the frequency tones of the at least one RU (103, 203) of the first MRU (102) and/or the second MRU (202).

15. The wireless network device (100) of claim 14, further configured to:

for the at least one RU (103, 203) of the first MRU (102) and/or the second MRU (202), applying only selected values of the first and/or second subsets of phase values (105, 205) selected for the at least one RU (103, 203) of the first MRU (102) and/or the second MRU (202) to the training sequence (104, 204) of the at least one RU (103, 203) of the first MRU (102) and/or the second MRU (202),

wherein the selected value is a value of the first and/or second subset of phase values (105, 205) associated with each frequency tone, each second frequency tone, or each fourth frequency tone of the at least one RU (103, 203) of the first MRU (102) and/or the second MRU (202).

16. The wireless network device (100) of claim 15, wherein:

selecting the first and/or second subset of phase values (105, 205) for the at least one RU (103, 203) of the first MRU (102) and/or the second MRU (202) based on whether the selected value is associated with each frequency tone, each second frequency tone, or each fourth frequency tone.

17. The wireless network device (100) according to any one of claims 1 to 16, wherein:

the first MRU (102) and/or the second MRU (202) comprise only larger RUs (103, 203), each RU (103, 203) having a bandwidth above 20MHz, or

The first MRU (102) and/or the second MRU (203) comprise only smaller RUs (103, 203), each RU (103, 203) having a bandwidth below 20 MHz.

18. The wireless network device (100) of any one of claims 1 to 17, wherein:

the training sequence (104, 204) of the first training signal (101) and/or the second training signal (201) comprises at least one of: a legacy long training field L-LTF sequence or a legacy short training field L-STF sequence or a very high throughput STF EHT-STF sequence, or an EHT-LTF sequence.

19. The wireless network device (100) of any of claims 1-18, further configured to:

providing an indication of the first and/or second subset of phase values (105, 205) for multiplying by the training sequence (104, 204) of the at least one RU (103, 203) of the first MRU (102) and/or the second MRU (202); or

Providing an indication of the first and/or second subset of phase values (105, 205) of the training sequence (104, 204) for the at least one RU (103, 203) multiplied by the first MRU (102) and/or the second MRU (202).

20. A method (300) for multi-resource unit, MRU, allocation in a wireless network, the method (300) comprising:

selecting (301) a first training signal (101) for a first MRU (102),

wherein the first MRU (102) comprises two or more RUs (103) arranged in the frequency domain,

for at least one RU (103) of the first MRU (102), applying (302) a first subset of phase values (105) to the training sequence (104) of the at least one RU (103) of the first MRU (102),

21. A computer program comprising a program code for performing the method (300) according to claim 20 when the program code runs on a computer.