Devices and methods for reliable communication in a wireless network

Abstract

A wireless transmitter station (110) is disclosed for transmitting a bit sequence to a wireless receiver station (120) over a channel (130) with a channel bandwidth using Orthogonal Frequency Division Multiplexing, OFDM, or Orthogonal Frequency Division Multiple Access, OFDMA, communication. The wireless transmitter station (110) is configured to encode the bit sequence using a forward error correction, FEC, encoder for obtaining an encoded bit sequence and pad the encoded bit sequence with post-FEC padding bits for obtaining a padded encoded bit sequence, wherein the number of bits of the padded encoded bit sequence is set for modulation over K tones of a resource unit, RU, defined by the IEEE 802.11 framework of standards.

Description

[0001] DEVICES AND METHODS FOR RELIABLE COMMUNICATION IN A WIRELESS NETWORK

[0002] TECHNICAL FIELD

[0003] The present invention relates to wireless communications. More specifically, the present invention relates to devices, in particular access points (APs) and non-AP stations, and methods for reliable OFDM and OFDMA communication in a wireless communication network, in particular a Wi-Fi network.

[0004] BACKGROUND

[0005] Reliability of data transmission in wireless communication networks is often assessed based on an upper bound of, for instance, the error rate and / or the latency of the data transmission. For instance, one of the modes of the Ultra-Reliable Low Latency Communication (URLLC) defined by the 3 GPP 5G standard defines an upper bound of 0.001% for the packet error rate, while maintaining a latency of at most 1 msec. Reliability is also an important aspect of Wi-Fi networks, as defined by the IEEE 802.11 framework of standards as well as further generations thereof, such as IEEE 802.1 Ibn (Ultra High Reliability, UHR, also referred to as Wi-Fi 8).

[0006] Uncontrolled and unexpected interference is one of the main factors preventing high reliability in wireless communication networks, in particular Wi-Fi networks. Interfering signals may occur in any bandwidth used within the Wi-Fi network. Narrowband interference, for instance, may arise from several sources, such as 2 MHz Narrowband- Assisted UWB (as part of IEEE 802.15.4ab), specifically in the 6 GHz band, and 1 / 2 / 4 MHz Bluetooth signals, in the 2.4 GHz band. Interference can arise at any time, e.g. before or during the transmission over a Wi-Fi link of a physical protocol data unit, PPDU, namely during transmission of the data-carrying part of a frame or packet. If the Wi-Fi transmitter identifies an ongoing interfering transmission in a certain frequency sub-band, it can refrain from using the corresponding sub-channel, for instance, by using preamble puncturing. This, however, cannot address unexpected interference arising during the transmission of a PPDU, which threatens the link reliability. The IEEE 802.1 Ibe Draft 4.0 standard specifies a DUP scheme which may mitigate wideband interference arising during the transmission of a PPDU, even though it was originally designed for coping with the different issue of decrease in the transmission power spectral density, PSD, mandated in certain frequency bands.

[0007] Within the IEEE 802.11 framework of standards enhancing reliability of packet transfer has usually been addressed by reducing the modulation order and / or coding rate defined by the modulation and coding scheme, MCS. For link conditions characterized by very low Signal to Interference plus Noise power Ratio, SINR, one is led to using the lowest MCS, which in IEEE 802.1 Ibe is BPSK rate Yi with dual-carrier modulation, DCM, and in some conditions (e.g. in the 6 GHz band) BPSK rate i with DCM and making use of the DUP scheme specified in the IEEE 802.1 Ibe Draft 4.0 standard. This is, however, quite limited in the case of relatively strong narrowband interference. Furthermore, the DUP scheme is defined only for channel bandwidths of at least 80 MHz (which means duplicating a minimum of 40 MHz chunks of the transmitted signal, for increasing the link reliability). With the DUP scheme, data using BPSK rate ’A, i.e. 0,5, with DCM (where the use of DCM effectively reduces the code rate to %, i.e. 0,25) is duplicated in the frequency domain using twice the bandwidth (with an additional partial sign change in order to reduce the PAPR), which is therefore roughly equivalent to using an extremely low MCS of BPSK with code rate of 1 / 8, i.e. 0,125.

[0008] Thus, the conventional reliability enhancement mechanisms are deficient on at least the two following accounts when it comes to interference which occupies just a narrow part of the full channel bandwidth. Firstly, the conventional mechanisms are not available for a channel bandwidth smaller than 80 MHz. Secondly, the conventional mechanisms compromise the total throughput by averaging the impact of a narrowband interference over the whole bandwidth, settling for transmission with low MCS and, thus, giving up on the available higher spectral efficiency in the non-interfered sub-bands of the channel bandwidth.

[0009] SUMMARY OF THE INVENTION

[0010] It is an objective of the present disclosure to provide improved devices, in particular access points and non-AP stations, and methods for reliable OFDM and OFDMA communication in a wireless network, in particular a Wi-Fi network. 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.

[0011] According to a first aspect a wireless transmitter station is provided for transmitting a bit sequence to a wireless receiver station over a channel with a channel bandwidth using Orthogonal Frequency Division Multiplexing, OFDM, or Orthogonal Frequency Division Multiple Access, OFDMA, communication. In an implementation form, the wireless transmitter station may be an access point, AP, or a non-AP station for a Wi-Fi network.

[0012] In a replication mode the wireless transmitter station is configured to encode the bit sequence using a forward error correction, FEC, encoder for obtaining an encoded bit sequence and pad the encoded bit sequence with post-FEC padding bits for obtaining a padded encoded bit sequence, wherein the number of bits of the padded encoded bit sequence is set for modulation over K tones of a resource unit, RU, defined by the IEEE 802.11 framework of standards.

[0013] The wireless transmitter station is further configured to generate, based on the plurality of bits of the padded encoded bit sequence, N-l further padded encoded bit sequences, wherein N is an integer greater than 1 and wherein the number of bits of each of the N-l further padded encoded bit sequences is equal to the number of bits of the padded encoded bit sequence.

[0014] Moreover, the wireless transmitter station is configured to apply a modulation and permutation operation to the padded encoded bit sequence and the N-l further padded encoded bit sequences for generating modulated data.

[0015] The wireless transmitter station is further configured to transmit the modulated data to the wireless receiver station over a further RU with N*K+d tones, wherein the further RU comprises N component RUs of size K and wherein d denotes an integer larger than or equal to 0, and wherein the further RU is an RU as defined by the IEEE 802.11 framework of standards for the channel bandwidth.

[0016] In a further possible implementation form, for applying the modulation and permutation operation to the padded encoded bit sequence and the N-l further padded encoded bit sequences for generating the modulated data, the wireless transmitter station is configured to: generate, based on the plurality of bits of the padded encoded bit sequence, a first set of quadrature-amplitude modulation, QAM, symbols and to generate, based on a respective plurality of bits of each of the N-l further padded encoded bit sequences, N-l further sets of QAM symbols; and permute the first set of QAM symbols and the N-l further sets of QAM symbols for generating the modulated data.

[0017] In a further possible implementation form, the wireless transmitter station is configured to permute the first set of QAM symbols and the N-l further sets of QAM symbols for generating the modulated data using a low-density parity code, LDPC, tone mapper.

[0018] In a further possible implementation form, for applying the modulation and permutation operation to the padded encoded bit sequence and the N-l further padded encoded bit sequences for generating the modulated data, the wireless transmitter station is configured to: permute the plurality of bits of the padded encoded bit sequence and a respective plurality of bits of each of the N-l further padded encoded bit sequences for obtaining a plurality of permuted padded encoded bit sequences; and generate, based on the plurality of permuted padded encoded bit sequences, a plurality of quadrature-amplitude modulation, QAM, symbols for generating the modulated data.

[0019] In a further possible implementation form, the wireless transmitter station is configured to permute the plurality of bits of the padded encoded bit sequence and the respective plurality of bits of each of the N-l further padded encoded bit sequences for obtaining the plurality of permuted padded encoded bit sequences using a binary convolutional code, BCC, interleaver.

[0020] In a further possible implementation from, the RU defined by the IEEE 802.11 framework of standards comprises 26, 52, 52+26, 106, 106+26, 242, 484, 484+242, 996, 996+484, or 2*996 tones.

[0021] In a further possible implementation form, the further RU defined by the IEEE 802.11 framework of standards for the channel bandwidth comprises 52, 52+26, 106, 106+26, 242, 484, 484+242, 996, 996+484, 996+484+242, 2*996, 2*996+484, 3*996, 3*996+484 or 4*996 tones. In a further possible implementation form, the wireless transmitter station is further configured to transmit information to the wireless receiver station indicative of the number of tones of the RU defined by the IEEE 802.11 framework of standards and / or the number of tones of the further RU defined by the IEEE 802.11 framework of standards for the channel bandwidth.

[0022] In a further possible implementation form, the wireless transmitter station is further configured to transmit information, in particular a flag bit to the wireless receiver station indicative of whether the wireless transmitter station is operating in the replication mode or another mode, for instance, a legacy mode.

[0023] In a further possible implementation form, the plurality of tones of the RU comprises a plurality of data tones and a plurality of Carrier Frequency Offset, CFO, pilot tones and the plurality of tones of the further RU comprises a plurality of further data tones and a plurality of further CFO pilot tones.

[0024] In a further possible implementation form, the number and location, i.e. frequency of the plurality of further CFO pilot tones is according to the IEEE 802.11 framework of standards.

[0025] In a further possible implementation form, the wireless transmitter station is configured to transmit the modulated data to the wireless receiver station as part of a data payload of a physical protocol data unit, PPDU.

[0026] In a further possible implementation form, the content, in particular a plurality of predefined QAM symbols and tone allocation of a short training field, STF, or long training field, LTF, included in a PHY preamble of the PPDU is based on the size and tone allocation of the further RU as defined by the IEEE 802.11 framework of standards.

[0027] In a further possible implementation form, the content and tone allocation of each of a plurality of short training fields, STFs, or long training fields, LTFs, included in the PHY preamble of the PPDU for each component RU of the further RU is based on the size and tone allocation of an RU with K tones as defined by the IEEE 802.11 framework of standards.

[0028] According to a second aspect a method is provided for transmitting a bit sequence to a wireless receiver station over a channel with a channel bandwidth using Orthogonal Frequency Division Multiplexing, OFDM, or Orthogonal Frequency Division Multiple Access, OFDMA, communication. The method according to the second aspect comprises the steps of: encoding the bit sequence using a forward error correction, FEC, encoder for obtaining an encoded bit sequence and padding the encoded bit sequence with post-FEC padding bits for obtaining a padded encoded bit sequence, wherein the number of bits of the padded encoded bit sequence is set for modulation over K tones of a resource unit, RU, defined by the IEEE 802.11 framework of standards; generating, based on the plurality of bits of the padded encoded bit sequence, N-l further padded encoded bit sequences, wherein N is an integer greater than 1 and wherein the number of bits of each of the N-l further padded encoded bit sequences is equal to the number of bits of the padded encoded bit sequence; applying a modulation and permutation operation to the padded encoded bit sequence and the N-l further padded encoded bit sequences for generating modulated data; and transmitting the modulated data to the wireless receiver station over a further RU with N*K+d tones, wherein the further RU comprises N component RUs of size K and wherein d denotes an integer larger than or equal to 0 and wherein the further RU is an RU as defined by the IEEE 802.11 framework of standards for the channel bandwidth.

[0029] The method according to the second aspect can be performed by the wireless transmitter station according to the first aspect. Thus, further features of the method according to the second aspect result directly from the functionality of the wireless transmitter station according to the first aspect as well as its different implementation forms described above and below.

[0030] According to a third aspect a wireless transmitter station is provided for transmitting a bit sequence to a wireless receiver station over a channel with a channel bandwidth using Orthogonal Frequency Division Multiplexing, OFDM, or Orthogonal Frequency Division Multiple Access, OFDMA, communication. In an implementation form, the wireless transmitter station may be an access point, AP, or a non-AP station for a Wi-Fi network.

[0031] In a replication mode the wireless transmitter station according to the third aspect is configured to encode the bit sequence using a forward error correction, FEC, encoder for obtaining an encoded bit sequence and pad the encoded bit sequence with post-FEC padding bits for obtaining a padded encoded bit sequence.

[0032] The wireless transmitter station according to the third aspect is further configured to generate, based on the plurality of bits of the padded encoded bit sequence, a first set of quadratureamplitude modulation, QAM, symbols for obtaining a first modulated data set using a first modulation operation, and generate, based on the plurality of bits of the padded encoded bit sequence, N-l further sets of QAM symbols for obtaining N-l further modulated data sets using N-l further modulation operations, wherein N is an integer greater than 1 and wherein each modulated data set of the first modulated data set and the N-l further modulated data sets defines modulated data for a respective component resource unit, RU, of a plurality of component RUs, wherein the number of tones of each component RU is equal to K and wherein K is the number of tones of a RU defined by the IEEE 802.11 framework of standards.

[0033] Moreover, the wireless transmitter station according to the third aspect is configured to apply low density parity code, LDPC, tone mapping of size K within each component RU and transmit the modulated data to the wireless receiver station over an RU with N*K+d tones, wherein d is an integer larger than or equal to 0 and wherein N*K+d is the number of tones of a further RU defined by the IEEE 802.11 framework of standards for the channel bandwidth. In an implementation form, the wireless transmitter station is further configured to transmit the modulated data to the wireless receiver station as part of a physical protocol data unit, PPDU.

[0034] In a further possible implementation form, the wireless transmitter station according to the third aspect is further configured to apply one or more predefined complex phase rotations to one or more segments of the first set of QAM symbols and / or the N-l further sets of QAM symbols for obtaining the first modulated data set and / or the N-l further modulated data sets.

[0035] In a further possible implementation form, the RU defined by the IEEE 802.11 framework of standards comprises 26, 52, 52+26, 106, 106+26, 242, 484, 484+242, 996, 996+484 or 2*996 tones.

[0036] In a further possible implementation form, the further RU defined by the IEEE 802.11 framework of standards for the channel bandwidth comprises 52, 52+26, 106, 106+26, 242, 484, 484+242, 996, 996+484, 2*996, 2*996+484, 3*996, 3*996+484 or 4*996 tones. In a further possible implementation form, the wireless transmitter station according to the third aspect is further configured to transmit information to the wireless receiver station indicative of the number of tones of the RU and / or the number of tones of the further RU defined by the IEEE 802.11 framework of standards for the channel bandwidth.

[0037] In a further possible implementation form, the wireless transmitter station according to the third aspect is further configured to transmit information, in particular a flag bit, to the wireless receiver station indicative of whether the wireless transmitter station is operating in the replication mode.

[0038] In a further possible implementation form, the plurality of tones of each component RU comprises a plurality of data tones and a plurality of Carrier Frequency Offset, CFO, pilot tones and wherein the plurality of tones of the further RU comprises a plurality of further data tones and a plurality of further CFO pilot tones.

[0039] In a further possible implementation form, the number of the plurality of further CFO pilot tones of the further RU is equal to N times the number of CFO pilot tones of each component RU.

[0040] In a further possible implementation form, the wireless transmitter station is configured to transmit the modulated data to the wireless receiver station as part of a data payload of a physical protocol data unit, PPDU.

[0041] In a further possible implementation form, the content and tone allocation of a short training field, STF, or long training field, LTF, included in a PHY preamble of the PPDU is based on the size and tone allocation of the further RU as defined by the IEEE 802.11 framework of standards.

[0042] In a further possible implementation form, the content and tone allocation of a short training field, STF, or long training field, LTF, included in the PHY preamble of the PPDU is based on the size and tone allocation of each component RU as defined by the IEEE 802.11 framework of standards.

[0043] According to a fourth aspect a method is provided for transmitting a bit sequence to a wireless receiver station over a channel with a channel bandwidth using Orthogonal Frequency Division Multiplexing, OFDM, or Orthogonal Frequency Division Multiple Access, OFDMA, communication. The method according to the fourth aspect comprises the steps of encoding the bit sequence using a forward error correction, FEC, encoder for obtaining an encoded bit sequence and padding the encoded bit sequence with post-FEC padding bits for obtaining a padded encoded bit sequence; generating, based on the plurality of bits of the padded encoded bit sequence, a first set of quadrature-amplitude modulation, QAM, symbols for obtaining a first modulated data set using a first modulation operation, and generating, based on the plurality of bits of the padded encoded bit sequence, N-l further sets of QAM symbols for obtaining N-l further modulated data sets using N-l further modulation operations, wherein N is an integer greater than 1 and wherein each modulated data set of the first modulated data set and the N-l further modulated data sets defines modulated data for a respective component resource unit, RU, of a plurality of component RUs, wherein the number of tones of each component RU is equal to K and wherein K is the number of tones of a RU defined by the IEEE 802.11 framework of standards; applying low density parity code, LDPC, tone mapping of size K within each component RU; and transmitting the modulated data to the wireless receiver station over an RU with N*K+d tones, wherein d is an integer larger than or equal to 0 and wherein N*K+d is the number of tones of a further RU defined by the IEEE 802.11 framework of standards for the channel bandwidth.

[0044] The method according to the fourth aspect can be performed by the wireless transmitter station according to the third aspect. Thus, further features of the method according to the fourth aspect result directly from the functionality of the wireless transmitter station according to the third aspect as well as its different implementation forms described above and below.

[0045] 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.

[0046] 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

[0047] In the following, embodiments of the present disclosure are described in more detail with reference to the attached figures and drawings, in which:

[0048] Fig. 1 shows a schematic diagram illustrating a wireless communication network, in particular a Wi-Fi network including a wireless transmitter station according to an embodiment in communication with a plurality of wireless receiver stations;

[0049] Fig. 2 shows a schematic diagram illustrating modules of a wireless transmitter station according to an embodiment for transmitting a bit sequence;

[0050] Figs. 3a, b show schematic diagrams illustrating conventional transmission processing chains implemented by a wireless transmitter station;

[0051] Figs. 4a-c show schematic diagrams illustrating transmission processing chains implemented by a wireless transmitter station according to different embodiments;

[0052] Figs. 5a, b show diagrams illustrating the RUs supported by the IEEE 802.11 framework of standards for a channel bandwidth of 20 MHz and 40 MHz, respectively;

[0053] Fig. 5c shows a schematic diagram illustrating phase rotations applied by a wireless transmitter station according to an embodiment for different RUs for a channel bandwidth of 20 MHz;

[0054] Figs. 6a, b show schematic diagrams illustrating the transmission of STF / LTF within a PHY preamble by a wireless transmitter station according to an embodiment;

[0055] Fig. 7 shows a flow diagram illustrating steps of a method according to an embodiment for transmitting a bit sequence to a wireless receiver station;

[0056] Fig. 8 shows a flow diagram illustrating steps of a method according to a further embodiment for transmitting a bit sequence to a wireless receiver station; and

[0057] Figs. 9a-c show graphs illustrating the performance of a wireless transmitter station according to different embodiments.

[0058] In the following, identical reference signs refer to identical or at least functionally equivalent features. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0059] In the following description, reference is made to the accompanying figures, which form part of the disclosure, which illustrate 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.

[0060] 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.

[0061] Figure 1 shows a wireless communication network 100, in particular a wireless communication network in accordance with the IEEE 802.11 framework of standards (also referred to as a Wi-Fi network 100). The Wi-Fi network 100 comprises a wireless transmitter station 110 (also referred to as Wi-Fi station 110 herein), which may be implemented in the form of a multi-antenna AP 110, and a plurality of wireless receiver stations 120 (also referred to as further Wi-Fi stations 120 herein) in the form of, for instance, non-AP stations 120. As illustrated in figure 1, by way of example, the non-AP stations 120 may comprise smartphones, laptop computers, tablet computers, desktop computers or other types of wireless devices 120. In the following, several embodiments of the AP 110 as wireless transmitter station 110 will be described in more detail. As will be appreciated, however, the non-AP stations 120 may be implemented as a wireless transmitter station as well in accordance with the following embodiments.

[0062] As further illustrated in figure 1, the AP 110 comprises 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.

[0063] Likewise, as indicated in figure 1, the non-AP station(s) 120 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.

[0064] As illustrated in figure 2, in an embodiment, the processing circuitry 111 of the AP 110 may implement an encoder 201, for instance, an LDPC encoder 201 configured to encode a message, i.e. a bit sequence m into one or more codewords c with a predefined coding rate. In an embodiment, the encoder 201 is configured to generate the codeword using one or more of the plurality of LDPC codes defined by the IEEE 802.11 framework of standards, for instance, IEEE 802.1 In, IEEE 802.1 lac, or any future evolution of the IEEE 802.11 framework of standards. As further illustrated in figure 2, in an embodiment, the AP 110 may further comprise a modulator 203 configured to modulate the codewords c generated by the encoder 201 based on, for instance, a QAM scheme into a plurality of modulation symbols, for instance, QAM symbols. In an embodiment, the modulator 203 is configured to modulate the codewords generated by the encoder 201 based on a BPSK, QPSK, 16-QAM, 64-QAM, 256-QAM, 1024-QAM and / or 4096-QAM scheme into the plurality of modulation symbols, i.e. the symbol stream s. In an embodiment, the modulator 203 is configured to modulate the codewords generated by the encoder 201 based on the modulation schemes defined by the IEEE 802.11 framework of standards.

[0065] In the embodiment shown in figure 2, the transmission processing chain of the AP 110 implemented by the processing circuitry 111 and / or the communication interface 113 of the AP 110 may further comprise an OFDM / OFDMA module 205 and an analog RF module 207. For instance, in case of IEEE 802.1 lac the symbol stream may be transmitted by an OFDM and / or OFDMA technique which may involve additional steps implemented by the OFDM / OFDMA module 205, such as a serial to parallel conversion before calculating an Inverse Fast Fourier Transform (IFFT). The analog RF module 207 may be configured to generate, based on the output from the OFDM / OFDMA module 205, the actual antenna feed signals for generating the RF transmission to the plurality of non-AP stations 120.

[0066] Before describing different embodiments of the wireless transmitter station 110, e.g. the AP 110 in more detail, in the following some technical background as well as terminology will be introduced making use of one or more of the following abbreviations:

[0067] AP Access Point

[0068] BCC Binary Convolutional Code

[0069] BPSK Binary Phase Shift Keying

[0070] BW Bandwidth

[0071] CCDF Complementary Cumulative Distribution Function

[0072] CFO Carrier Frequency Offset

[0073] CSD Cyclic Shift Delay

[0074] DCM Dual-Carrier Modulation

[0075] DUP Duplicate Transmission (defined in the IEEE 802.1 Ibe standard)

[0076] IDFT / IFFT Inverse Discrete / Fast Fourier Transform

[0077] IEEE Institute of Electrical and Electronics Engineers LDPC Low Density Parity Check

[0078] LTF Long Training Field

[0079] MCS Modulation and Coding Scheme (Rate)

[0080] MIMO Multiple Input Multiple Output

[0081] MU Multi-User

[0082] OFDM / A Orthogonal Frequency Division Multiplexing / Multiple- Access

[0083] PAPR Peak-to- Average Power Ratio

[0084] PER Packet Error Rate

[0085] PHY Physical layer

[0086] PPDU PHY Protocol Data Unit

[0087] PSD Power Spectral Density

[0088] QAM Quadrature Amplitude Modulation

[0089] RU Resource Unit

[0090] RX / Rx Receiver

[0091] SINR Signal to Interference and Noise power Ratio

[0092] SIR Signal to Interference power Ratio

[0093] SNR Signal to Noise power Ratio

[0094] SS Spatial Stream

[0095] STA Station, may be an AP STA or a non-AP STA

[0096] STF Short Training Field

[0097] SU Single-User

[0098] TX / Tx Transmitter

[0099] UHR Ultra High Reliability

[0100] U-SIG Universal SIG (name of a signal field in 802.1 Ibe)

[0101] UWB Ultra-Wide-Band

[0102] WLAN Wireless Local Access Network

[0103] IEEE 802.11 WLAN standards prior to 802.1 lax (including 802.1 la / g / n / ac) supported only OFDM mode, where the entire BW was used to transmit data to a single STA or multiple STAs (in a multi-user MIMO mode). Starting with 802.1 lax (and then 802.1 Ibe), OFDMA is supported, where non-overlapping portions of the BW (called Resource Units or RUs) can be allocated to one or more STAs. The standard defines the RUs supported for different bandwidths of the channel, for instance, 20 MHz and 40 MHz BW. In particular for the case of 20 MHz, the transmitter may choose to transmit on the entire BW using a 242-tone RU (to one or more STAs, the latter by transmitting in an MU-MIMO mode), or using OFDMA where any combination of non-overlapping RUs, smaller than 242-tones, can be used. In particular, the transmitter may choose to transmit on RUs of size 26-tones, 52-tones or 106- tones. In 802.1 lax and 802.1 Ibe, each receiving STA can be allocated a single RU within a data frame which may contain data intended for multiple receiving STAs. It is important to note that whereas a 52-tone RU is exactly double the size of a 26-tone RU, a 106-tone RU is slightly larger than two 52-tone RUs (there are 2 additional tones) and a 242-tone RU is larger than two 106-tone RUs (there are 30 additional tones).

[0104] Figures 3a and 3b show schematic diagrams illustrating conventional transmission processing chains in compliance with the IEEE 802.11 framework of standards. These conventional transmission processing chains are described in more detail here in order to better contrast the transmission processing chains implemented by the wireless transmitter station 110 according to an embodiment, which will be described in more detail below in the context of figures 4a-c. In an embodiment, the wireless transmitter station 110 may be configured to operate in a replication mode (described in more detail below) and in a legacy mode, wherein in the legacy mode the wireless transmitter station 110 is configured to implement the transmission processing chain illustrated in figure 3a and / or the transmission processing chain illustrated in figure 3b.

[0105] Figure 3a illustrates the transmission processing chain for LDPC-encoded data as defined by the IEEE 802.11 framework of standards, in particular IEEE 802.1 Ibe and 802.1 lax. Bits from the MAC layer undergo pre-FEC padding in a block 301 (if applicable), scrambling in a block 303, encoding using an LDPC encoder 305, and post-FEC padding 306. If multiple spatial streams are used the post-FEC padded bits are divided by a stream parser 307 between the spatial streams before they are fed into a respective constellation mapper 309 which applies a constellation mapping procedure (such as BPSK / QPSK / 16-QAM and the like) onto the bit streams. The resulting modulation symbols, in particular QAM symbols, are interleaved in frequency using a LDPC Tone Mapper 311, then a cyclic shift delay, CSD, may be applied per spatial stream by a block 312 followed by spatial mapping (e.g. beamforming) and then mapping to subcarriers (see block 313) before the application of the IDFT / IFFT operation by blocks 315, which creates the samples of the OFDM symbol in the time domain. Finally, a guard interval may be inserted in block 317 and the analog and RF blocks 319 may generate the actual antenna feed signals, based on the output from the preceding blocks, for generating the RF transmission to the plurality of wireless receiver stations 120, e.g. the non- AP stations 120. As will be appreciated, the frequency mapping block 313 maps each STA’s allocation onto the used subcarriers / tones in frequency, before the IDFT / IFFT blocks 315 which operate on an entire OFDM symbol (the latter may contain data allocated to multiple target stations). In other words, all blocks, i.e. modules prior to the frequency mapping operation are carried out per allocation, independently.

[0106] Figure 3b illustrates the transmission processing chain for BCC-encoded data as defined by the IEEE 802.11 framework of standards, in particular IEEE 802.1 Ibe and 802.1 lax. Bits from the MAC layer undergo pre-FEC padding by block 301 (if applicable), scrambling by block 303, encoding using a BCC encoder 305, and post-FEC padding by a block 306.

[0107] If multiple spatial streams are used the post-FEC padded bits are divided by a stream parser 307 between the spatial streams. The bits then undergo interleaving by a respective BCC interleaver block 309 and mapping to points of a selected constellation (such as BPSK / QPSK / 16-QAM and the like) by a respective constellation mapper 311. A CSD may be applied per spatial stream by a respective block 312 followed by spatial mapping (e.g. beamforming) and then mapping to subcarriers (see block 313) before the application of the IDFT / IFFT operation by blocks 315, which creates the samples of the OFDM symbol in the time domain. Finally, a guard interval may be inserted in block 317 and the analog and RF blocks 319 may generate the actual antenna feed signals, based on the output from the preceding blocks, for generating the RF transmission to the plurality of wireless receiver stations, e.g. the non-AP stations 120. As will be appreciated, the frequency mapping block / module 313 maps each STA’s allocation onto the used subcarriers / tones in frequency, before the IDFT / IFFT block / module 315 which operates on an entire OFDM symbol (the latter may contain multiple allocations). In other words, all blocks / modules prior to the frequency mapping operation are carried out per allocation, independently.

[0108] Both standards IEEE 802.1 lax and 802.1 Ibe define the operation of BCC interleaving (see blocks 309 of figure 3b) and LDPC tone-mapping (see blocks 311 of figure 3 a) for every valid RU size. The interleaving parameters defined for every RU size are intended to avoid a too small separation between tones of the RU which carry the information encoded by contiguous bits (or QAMs) in the payload, to yield sufficient frequency diversity and improve detection performance at the wireless receiver station 120. In order to track and compensate any residual carrier frequency offset, CFO, and phase noise, CFO pilots (represented as predefined BPSK symbols modulating specific predefined tones, both known to the wireless receiver station) are transmitted throughout the PPDU, and are inserted into almost every transmitted OFDM symbol in the frame, including OFDM symbols carrying LTF and data. The number of CFO pilots are defined by the IEEE 802.11 framework of standards for different RUs in the following way:

[0109] - 26-tone RU: 2 CFO pilots (the remaining 24 tones are used for data) 52-tone RU: 4 CFO pilots (the remaining 48 tones are used for data) 106-tone RU: 4 CFO pilots (the remaining 102 tones are used for data)

[0110] - 242-tone RU: 8 CFO pilots (the remaining 234 tones are used for data)

[0111] - 484-tone RU: 16 CFO pilots (the remaining 468 tones are used for data)

[0112] CFO pilots do not undergo LDPC tone-mapping or BCC interleaving.

[0113] Figures 4a-c show schematic diagrams illustrating transmission processing chains implemented by the wireless transmitter station 110 (or as mentioned above 120) according to different embodiments. Generally, these embodiments are based on the idea of exploiting the OFDM / OFDMA-based waveforms used in the Wi-Fi network 100 by transmitting the same data (i.e. replicas of the data) in multiple RUs (herein also referred to as component RUs) by the wireless transmitter station 110 such that the wireless receiver station(s) 120 may combine or ignore (or, more generally, combine with different weights) RU / sub carriers according to the (monitored) interference levels experienced by them, thus increasing the probability that a transmission is successfully decoded. As already mentioned above, according to embodiments disclosed herein this may be implemented using both OFDM or OFDMA communication. For instance, the wireless transmitter station 110, e.g. AP 110 may transmit using OFDMA to multiple wireless receiver stations 120, e.g. non-AP stations 120, where only one of the wireless receiver stations 120 is allocated a replicated allocation for higher reliability, whereas all other allocations are transmitted without replication.

[0114] As will be appreciated and described in more detail in the following, unlike in PSD-limited scenarios, where replication of data is motivated by the inability to increase the total transmission power, embodiments disclosed herein don’t focus on improving the SNR, but rather on reducing or coping with the negative impact of interference. One major advantage of this approach implemented by embodiments disclosed herein is that in many scenarios the data can still be transmitted using medium to high MCS (as is suitable in the absence of the interference). In embodiments disclosed herein the replication within 40 MHz or narrower subchannels may be limited to “allowed” (i.e. already defined in the IEEE 802.11 framework of standards) original RUs of the same size (namely, multiple 26-tone or 52-tone or 106-tone or 242-tone RUs). Further embodiments will be described below for the specific designs for both data RUs and STF / LTF signals so that PAPR is kept low (an always desirable property for the transmitted signal).

[0115] As used herein, the original RU which is being replicated may be referred to as the “original RU”, while the larger RU created by replicating the original RU may be referred to as a “postreplication RU”. According to embodiments disclosed herein, the “post-replication RU” is created by replicating the “original RU” an integer number of times, where in certain embodiments the frequency allocation of each replica may be referred to as a “component RU”. If the number of tones of the “post-replication RU” is not an integer multiple of the number of tones of the “original RU”, the remaining unused tones may be set to zero. For example, if a 52-tone “original RU” is duplicated to form a “post-replication RU” of size 106, two null tones may be used (in locations indicated by “null subcarriers” in figure 5a). If a 106- tone “original RU” is duplicated to form a “post-replication RU” of size 242, thirty zero tones may be used (in locations indicated by “null subcarriers” as well as the center 26-tone RU in figure 5 a).

[0116] Figure 4a shows the transmission processing chains implemented by the wireless transmitter station 110 according to a first main embodiment operating in a replication mode, wherein the original RU is replicated prior to the LDPC tone mapping stage. For this first main embodiment, the wireless transmitter station 110 is generally configured to implement the following processing stages, when operating in the replication mode: encode a desired bit sequence using a forward error correction, FEC, encoder, such as the LDPC encoder 405 of figure 4a, for obtaining an encoded bit sequence and pad the encoded bit sequence with post-FEC padding bits for obtaining a padded encoded bit sequence; generate, based on the plurality of bits of the padded encoded bit sequence, a first set of quadrature-amplitude modulation, QAM, symbols for obtaining a first modulated data set using a first modulation operation, and generate, based on the plurality of bits of the padded encoded bit sequence, N-l further sets of QAM symbols for obtaining N-l further modulated data sets using N-l further modulation operations, wherein N is an integer greater than 1 and wherein each modulated data set of the first modulated data set and the N-l further modulated data sets defines modulated data for a respective component resource unit, RU, of a plurality of component RUs, wherein the number of tones of each component RU is equal to K and wherein K is the number of tones of a RU defined by the IEEE 802.11 framework of standards; apply low density parity code, LDPC, tone mapping of size K within each component RU; and transmit the modulated data to the wireless receiver station(s) 120 over an RU with N*K+d tones, wherein d is an integer larger than or equal to 0 and wherein N*K+d is the number of tones of a further RU defined by the IEEE 802.11 framework of standards for the channel bandwidth. In an embodiment, the wireless transmitter station 110 may be configured to transmit the modulated data to the wireless receiver station(s) 120 as part of a physical protocol data unit, PPDU.

[0117] In the more detailed embodiment shown in figure 4a, the wireless transmitter station 110 is configured to implement the following processing stages, when operating in the replication mode. Like in the conventional transmission chains illustrated in figure 3a the bits of the bit sequence provided by the MAC layer undergo pre-FEC padding in a block 401 (if applicable), scrambling in a block 403, encoding using an FEC encoder in the form of LDPC encoder 405, and post-FEC padding in block 406. If multiple spatial streams are used, the post-FEC padded bits are divided by a stream parser 407 between the spatial streams and then mapped to points of the selected constellation (e.g. BPSK / QPSK / 16-QAM and the like) by a respective constellation mapper 409. At this stage, the wireless transmitter station 110 is configured by means of the blocks 410a to generate the N-l replicas of the original modulated (QAM) symbols, each of the N-l replicas corresponding to a replicated RU. As will be described in more detail below, specific phase rotations may be applied to the output of replication blocks 410a. The resulting replicated modulation symbols are interleaved in frequency using a LDPC Tone Mapper 411 and then a CSD may be applied per spatial stream by a respective block 412. . This is followed by spatial mapping (e.g. beamforming) and then mapping to subcarriers (see block 413) before the application of the IDFT / IFFT operation by blocks 415, which creates the samples of the OFDM symbol in the time domain. Finally, a guard interval may be inserted in blocks 417 and the analog and RF blocks 419 may generate the actual antenna feed signals, based on the output from the preceding blocks, for generating the RF transmission to the wireless receiver station(s) 120.

[0118] As will be appreciated, the blocks 401 to 409 of figure 4a may be implemented by the wireless transmitter station 110 according to an embodiment in compliance with the procedures of the data field construction as defined in the IEEE 802.11 family of standards in preparation for transmission of data over an RU of size K, i.e. an RU having K tones or subcarriers. In the replication blocks 410a implemented by the wireless transmitter station 110 according to an embodiment, N*K (possibly phase-rotated, as will be described in more detail below) QAM symbols are prepared for transmission over a combined physical RU of size (N*K + d), where N is the total number of replicas and d > 0 is the number of additional null subcarriers.

[0119] Figures 4b and 4c show the transmission processing chains implemented by the wireless transmitter station 110 according to two second main embodiments operating in a replication mode, wherein the original RU is replicated prior to a LDPC tone mapping stage (embodiment shown in figure 4b) or a BCC interleaving stage (embodiment shown in figure 4c). In other words, in these embodiments the bits (in case of BCC) or QAMs (in case of LDPC) are first replicated onto multiple RUs, and then undergo BCC interleaving or LDPC tone mapping within the plurality, i.e. all data tones of the post-replication RU onto which they were replicated. For these two second main embodiments, the wireless transmitter station 110 is generally configured to implement the following processing stages, when operating in the replication mode: encode a bit sequence using a forward error correction, FEC, encoder 405 for obtaining an encoded bit sequence and pad the encoded bit sequence with post-FEC padding bits for obtaining a padded encoded bit sequence, wherein the number of bits of the padded encoded bit sequence is set for modulation over K tones of a resource unit, RU, defined by the IEEE 802.11 framework of standards; generate, based on the plurality of bits of the padded encoded bit sequence, N-l further padded encoded bit sequences, wherein N is an integer greater than 1 and wherein the number of bits of each of the N-l further padded encoded bit sequences is equal to the number of bits of the padded encoded bit sequence; apply a modulation and permutation operation to the padded encoded bit sequence and the N- 1 further padded encoded bit sequences for generating modulated data; transmit the modulated data to the wireless receiver station(s) 120 over a further RU with N*K+d tones, wherein the further RU comprises N component RUs of size K and wherein d denotes an integer larger than or equal to 0, and wherein the further RU is an RU as defined by the IEEE 802.11 framework of standards for the channel bandwidth. In an embodiment, the wireless transmitter station 110 may be configured to transmit the modulated data to the wireless receiver station(s) 120 as part of a physical protocol data unit, PPDU.

[0120] In the more detailed embodiment shown in figure 4b, the wireless transmitter station 110 is configured to implement the following processing stages, when operating in the replication mode. Like in the conventional transmission chains illustrated in figure 3a the bits of the bit sequence provided by the MAC layer undergo pre-FEC padding in a block 401 (if applicable), scrambling in a block 403, encoding using an FEC encoder in the form of an LDPC encoder 405, and post-FEC padding in block406. If multiple spatial streams are used the post-FEC padded bits are divided by a stream parser 407 between the spatial streams and then mapped to points of the selected constellation (e.g. BPSK / QPSK / 16-QAM and the like) by a respective constellation mapper 409. A respective replication block 410 is configured to replicate the modulation symbols provided by the respective constellation mapper 409. The modulation symbols, in particular QAM symbols of the original RU and the N-l replications thereof, are interleaved in frequency using a LDPC Tone Mapper 411 and then a CSD may be applied per spatial stream by a block 412. This is followed by spatial mapping (e.g. beamforming) and then mapping to subcarriers (see block 413) before the application of the IDFT / IFFT operation by blocks 415, which creates the samples of the OFDM symbol in the time domain. Finally, a guard interval may be inserted in blocks 417 and the analog and RF blocks 419 may generate the actual antenna feed signals, based on the output from the preceding blocks, for generating the RF transmission to the wireless receiver station(s) 120.

[0121] As will be appreciated, the blocks 401 to 409 of figure 4b may be implemented by the wireless transmitter station 110 according to an embodiment in compliance with the procedures of the data field construction as defined in the IEEE 802.11 family of standards in preparation for transmission of data over an RU of size K, i.e. an RU having K tones or subcarriers. In the replication blocks 410 implemented by the wireless transmitter station 110 according to an embodiment, N*K QAM symbols are prepared for transmission over a combined physical RU of size N*K+d ), where N is the total number of replicas and d > 0 is the number of additional null subcarriers. Accordingly, also the processing blocks downstream of the replication blocks 410, particularly the LDPC Tone Mapper 411, operate according to the size of the combined RU.

[0122] In the more detailed embodiment shown in figure 4c, the wireless transmitter station 110 is configured to implement the following processing stages, when operating in the replication mode. Like in the conventional transmission chains illustrated in figure 3b the bits of the bit sequence provided by the MAC layer undergo pre-FEC padding in a block 401 (if applicable), scrambling in a block 403, encoding using an FEC encoder in the form of a BCC encoder 405, and post-FEC padding in block 406. If multiple spatial streams are used the post-FEC padded bits are divided by a stream parser 407 between the spatial streams. A respective replication block 409 is configured to replicate the bits provided by the stream parser 407. The bits of the original RU and the N-l replicas thereof then undergo interleaving by a respective BCC interleaver block 410 and mapping to points of a selected constellation (e.g. BPSK / QPSK / 16-QAM and the like) by a respective constellation mapper 411. A CSD may be applied per spatial stream by a respective block 412 followed by spatial mapping (e.g. beamforming) and then mapping to subcarriers (see block 413) before the application of the IDFT / IFFT operation by blocks 415, which creates the samples of the OFDM symbol in the time domain. Finally, a guard interval may be inserted in blocks 417 and the analog and RF blocks 419 may generate the actual antenna feed signals, based on the output from the preceding blocks, for generating the RF transmission to the plurality of non-AP stations 120.

[0123] As will be appreciated, the blocks 401 to 407 of figure 4c may be implemented by the wireless transmitter station 110 according to an embodiment in compliance with the procedures of the data field construction as defined in the IEEE 802.11 family of standards in preparation for transmission of data over an RU of size K, i.e. an RU having K tones or subcarriers. In the replication blocks 409 implemented by the wireless transmitter station 110 according to an embodiment a combined encoded bit sequence (comprising N replicas) is prepared for modulation and transmission over a combined physical RU of size (N*K + d), where N is the total number of replicas (including the original) and d > 0 is the number of additional null subcarriers. Accordingly, processing blocks downstream of the replication blocks 409, particularly the BCC Interleaver blocks 410, operate according to the size of the combined RU. In an embodiment, the wireless transmitter station 110 according to the first main embodiment illustrated in figure 4a may be configured to replicate CFO (tracking) pilots from their original location in the original RU. For instance, if an original RU of size 52-tones is duplicated to a 106-tone post-replication RU, then there may be 2x48=96 data subcarriers after replication and 2x4=8 CFO pilots after replication. For the wireless transmitter station 110 according to the second main embodiments illustrated in figures 4b and 4c the CFO pilots are not replicated but their number and location may be taken from the corresponding indices of the post-replication RU size. For example, if an original 52-tone RU is duplicated to form a 106-tone post-replication RU, then there are 2x48=96 data tones (after replication) and 4 CFO pilots in the post-replication RU with their location as is defined for a 106-tone RU.

[0124] As already described above, for the first main embodiment illustrated in figure 4a the wireless transmitter station 110 may be configured to apply one or more predefined complex phase rotations (for instance, by means of the processing blocks 410b shown in figure 4a) to one or more segments of the QAM symbols of the original RU and the QAM symbols of the N-l replica thereof in order to reduce the PAPR. More specifically, in an embodiment the wireless transmitter station 110 may be configured to apply the following phase rotations after replication:

[0125] • For 40 MHz and wider BW (based on replication of 242-tone RUs), use legacy phase rotations, defined in the IEEE 802.11 framework of standards, as multiplication factors to be applied to the QAM symbols mapped over different segments of the whole RU in frequency domain.

[0126] • For transmission to a STA (or group of STAs) over a 242-tone RU (20 MHz), use the following phase rotations: o 106-tone replicas: [1 1 -1 1] per a respective segment, each segment comprising 106 / 2 = 53 tones (see 505 of figure 5c) o 52-tone replicas: [1 1 1 1 1 -1 -1 1] per a respective segment, each segment comprising 52 / 2 = 26 tones (see 503 of figure 5c) o 26-tone replicas: [1 1 1 1 -1 -1 -1 -1 1] per a respective 26-tone RU (as 501 of figure 5 c)

[0127] • For transmission to a STA (or group of STAs) over a 106-tone RU, use the following phase rotations: o 52-tone replicas: [1 -1] per a respective replica o 26-tone replicas: [1 1 -1 1] per a respective replica

[0128] • For transmission to a STA (or group of STAs) over a 52-tone RU, use the following phase rotations: o 26-tone replicas: [1 -1] per a respective replica

[0129] As will be appreciated, for the wireless transmitter station 110 according to the second main embodiments, illustrated in figures 4b and 4c, PAPR reduction sequences generated by the phase rotations described above may not be necessary, due to the spreading of QAM symbols across a larger BW with LDPC tone mapping or BCC interleaving, which does not increase the PAPR (as opposed to replication in the frequency domain of the same signal, as may occur in the embodiment illustrated in figure 4a).

[0130] As already described above, in an embodiment, the wireless transmitter station 110 is configured to make the transmission to the wireless receiver station(s) 120 based on a physical protocol data unit, PPDU, which may include a PHY preamble and / or one or more further fields defined by the IEEE 802.11 framework of standards. For instance, the STF / LTF signal defined by IEEE 802.1 Ibn (also referred to as UHR), namely the corresponding parts of the PHY preamble which precedes the replicated data, may be implemented by the wireless transmitter station 110 according to the following options. According to a first embodiment illustrated in figure 6a, the STF / LTF signal may adhere to the OFDMA pattern (defined in IEEE 802.1 lax / be) that corresponds to the post-replicated RUs 601, 603, 605, and 607.

[0131] According to a further embodiment illustrated in figure 6b, the STF / LTF signal may adhere to a non-OFDMA pattern (meaning all tones are used; in other words - OFDM using the entire BW) where all the tones of the ‘post-replication RU’ (242-tone in the example shown in figure 6b) are used, and there are no null tones. This ensures lower STF / LTF PAPR, but may waste communication resources and may require the wireless receiver station(s) 120 to compensate for power difference per tone (between the STF / LTF and data parts) during the equalization stage in the demodulation stage of the data detection process.

[0132] As already described above, in an embodiment, the wireless transmitter station 110 may be configured to operate in a legacy mode (using no replication of RUs) or the replication mode (using the replication of RUs described above). In an embodiment, the wireless transmitter station 110 is configured to signal, i.e. indicate to the wireless receiver station(s) 120, the mode employed for data replication in the PPDU used for transmission, for instance, by means of certain subfields in the PHY preamble.

[0133] According to an embodiment, the size of the “post-replication RU” may be signaled by the wireless transmitter station 110 in the conventional way (i.e. in U-SIG in case of SU or UHR- SIG in case of MU / OFDMA). In an embodiment, the wireless transmitter station 110 may use 2 bits to signal the size of original RU which is replicated (representing the four options of no duplication, 26, 52, or 106 tones). In a further embodiment, in case of a 484-tone postreplication RU, the replication of a 26-tone RU may not be allowed / used. For a postreplication 484-tone RU, 2 bits may be used to signal the size of original RU which is replicated (either no duplication, 52, 106, or 242 tones).

[0134] According to a further embodiment, the wireless transmitter station 110 may be configured to use a single bit, i.e. flag bit to indicate if there is replication or not, i.e. if a transmission by the wireless transmitter station 110 is using the replication mode or the legacy mode. In this case there may be a fixed BW-dependent rule for the replication scheme: for a 52-tone RU, only the replication of 26-tone RU is supported; for a 106-tone RU, only the replication of 52-tone RU is supported; for a 242-tone RU, only one option out of the following two replication strategies is supported, either of 106-tone or 52-tone original RUs; for a 484-tone RU, only one option out of the following two replication strategies is supported, either of 106-tone or 242-tone RUs.

[0135] According to a further embodiment, the wireless transmitter station 110 may use a fixed rule (defined, for instance, by a standard) for the number of replications (e.g. 2 or 4) per any RU size, such as always use replication of 4x52-tone in a 242-tone RU or always use replication of 2x52-tone in a 106-tone RU.

[0136] In an embodiment, for the RU allocation in UHR-SIG (or in U-SIG for the SU case) the wireless transmitter station 110 is configured to indicate the post-replication RU (e.g. 242- tone or 484-tone RU) in the conventional way, as defined by the IEEE 802.11 framework of standards.

[0137] Figure 7 shows a flow diagram illustrating steps of a method 700 for transmitting a bit sequence to a wireless receiver station(s) 120 over a channel 130 with a channel bandwidth using Orthogonal Frequency Division Multiplexing, OFDM, or Orthogonal Frequency

[0138] Division Multiple Access, OFDMA, communication. The method 700 comprises a step 701 of encoding the bit sequence using a forward error correction, FEC, encoder 405 for obtaining an encoded bit sequence and padding the encoded bit sequence with post-FEC padding bits for obtaining a padded encoded bit sequence, wherein the number of bits of the padded encoded bit sequence is set for modulation over K tones of a resource unit, RU, defined by the IEEE 802.11 framework of standards. Moreover, the method 700 comprises a step 703 of generating, based on the plurality of bits of the padded encoded bit sequence, N-l further padded encoded bit sequences, wherein N is an integer greater than 1 and wherein the number of bits of each of the N-l further padded encoded bit sequences is equal to the number of bits of the padded encoded bit sequence. The method 700 further comprises a step 705 of applying a modulation and permutation operation to the padded encoded bit sequence and the N-l further padded encoded bit sequences for generating modulated data and a step 707 of transmitting the modulated data to the wireless receiver station 120 over a further RU with N*K+d tones, wherein the further RU comprises N component RUs of size K and wherein d denotes an integer larger than or equal to 0 and wherein the further RU is an RU as defined by the IEEE 802.11 framework of standards for the channel bandwidth.

[0139] Figure 8 shows a flow diagram illustrating steps of a method 800 for transmitting a bit sequence to a wireless receiver station 120 over a channel 130 with a channel bandwidth using Orthogonal Frequency Division Multiplexing, OFDM, or Orthogonal Frequency Division Multiple Access, OFDMA, communication. The method 800 comprises a step 801 of encoding the bit sequence using a forward error correction, FEC, encoder 405 for obtaining an encoded bit sequence and padding the encoded bit sequence with post-FEC padding bits for obtaining a padded encoded bit sequence. Moreover, the method 800 comprises a step 803 of generating, based on the plurality of bits of the padded encoded bit sequence, a first set of quadrature-amplitude modulation, QAM, symbols for obtaining a first modulated data set using a first modulation operation, and generating, based on the plurality of bits of the padded encoded bit sequence, N-l further sets of QAM symbols for obtaining N-l further modulated data sets using N-l further modulation operations, wherein N is an integer greater than 1 and wherein each modulated data set of the first modulated data set and the N-l further modulated data sets defines modulated data for a respective component resource unit, RU, of a plurality of component RUs, wherein the number of tones of each component RU is equal to K and wherein K is the number of tones of a RU defined by the IEEE 802.11 framework of standards. The method 800 further comprises a step 805 of applying low density parity code, LDPC, tone mapping of size K within each component RU and a step 807 of transmitting the modulated data to the wireless receiver station 120 over an RU with N*K+d tones, wherein d is an integer larger than or equal to 0 and wherein N*K+d is the number of tones of a further RU defined by the IEEE 802.11 framework of standards for the channel bandwidth.

[0140] Figures 9a-c show graphs illustrating some performance aspects of the wireless transmitter station 110 and the communication link between the wireless transmitter station 110 and a wireless receiver station(s) 120, according to different embodiments. Generally, embodiments of the wireless transmitter station 110 disclosed herein allow improving the reliability by enabling transmission of data allocated over multiple RUs in a simple manner. Moreover, embodiments of the wireless transmitter station 110 are configured to signal to the wireless receiver station(s) 120 the extra steps in the signal generation process performed at the wireless transmitter station 110 such that wireless receiver station(s) 120 has the flexibility of how to efficiently combine replicated signals transmitted over frequency resources suffering from different interference levels. Figure 9a shows simulation results for the scenario of an RU carrying data encoded and modulated using MCS 4, over a 20 MHz channel of type TGn- D NLOS (modeled according to the IEEE 802.1 In standard methodology); SIR = 0 dB in the 2 MHz subband within the channel where interference is activated; 2 Tx antennas, 4 Rx antennas, 1 SS. The SNR-dependent packet error rate, PER, results of the communication link are shown in figure 9a for three cases, i.e. TX-RX schemes, namely case A with no replication as a baseline; case B, with replication (x2 using a smaller RU replicated 2 times) employed at the transmitter side 110 and with the wireless receiver station(s) 120 ‘blindly’ combining all received modulated symbol replicas, with no attempt to detect the interference; and case C, with replication (x2 using a smaller RU replicated 2 times) and with the wireless receiver station(s) 120 identifying the interference before combining the received replicated modulated symbols, ignoring symbols received within the interfered subband. As will be appreciated, case C yields a huge improvement (i.e. reduction in the PER metric) and significantly enhances the reliability (the curves for case A (no replication) and case B (replication without identifying interference) exhibit an error floor).

[0141] Figures 9b and 9c demonstrate the lower PAPR of the transmitted waveform achieved when using the phase rotations described above for 106-tone and 52-tone RUs over a 242-tone RU (in comparison to the case without applying these phase rotations).

[0142] 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).

[0143] 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.

[0144] 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.

[0145] In addition, functional units in the embodiments of the invention may be integrated into one processing unit, or each of the units may exist alone physically, or two or more units are integrated into one unit.

Claims

CLAIMS1. A wireless transmitter station (110; 120) for transmitting a bit sequence to a wireless receiver station (120; 110) over a channel (130) with a channel bandwidth using Orthogonal Frequency Division Multiplexing, OFDM, or Orthogonal Frequency Division Multiple Access, OFDMA, communication, wherein in a replication mode the wireless transmitter station (110; 120) is configured to: encode the bit sequence using a forward error correction, FEC, encoder (405) for obtaining an encoded bit sequence and pad the encoded bit sequence with post-FEC padding bits for obtaining a padded encoded bit sequence, wherein the number of bits of the padded encoded bit sequence is set for modulation over K tones of a resource unit, RU, defined by the IEEE 802.11 framework of standards; generate, based on the plurality of bits of the padded encoded bit sequence, N-l further padded encoded bit sequences, wherein N is an integer greater than 1 and wherein the number of bits of each of the N-l further padded encoded bit sequences is equal to the number of bits of the padded encoded bit sequence; apply a modulation and permutation operation to the padded encoded bit sequence and the N- 1 further padded encoded bit sequences for generating modulated data; transmit the modulated data to the wireless receiver station (120; 110) over a further RU with N*K+d tones, wherein the further RU comprises N component RUs of size K and wherein d denotes an integer larger than or equal to 0, and wherein the further RU is an RU as defined by the IEEE 802.11 framework of standards for the channel bandwidth.

2. The wireless transmitter station (110; 120) of claim 1, wherein for applying the modulation and permutation operation to the padded encoded bit sequence and the N-l further padded encoded bit sequences for generating the modulated data the wireless transmitter station (110; 120) is configured to: generate, based on the plurality of bits of the padded encoded bit sequence, a first set of quadrature-amplitude modulation, QAM, symbols and to generate, based on a respective plurality of bits of each of the N-l further padded encoded bit sequences, N-l further sets of QAM symbols; andpermute the first set of QAM symbols and the N-l further sets of QAM symbols for generating the modulated data.

3. The wireless transmitter station (110; 120) of claim 2, wherein the wireless transmitter station (110; 120) is configured to permute the first set of QAM symbols and the N-l further sets of QAM symbols for generating the modulated data using a low-density parity code, LDPC, tone mapper (411).

4. The wireless transmitter station (110; 120) of claim 1, wherein for applying the modulation and permutation operation to the padded encoded bit sequence and the N-l further padded encoded bit sequences for generating the modulated data the wireless transmitter station (110; 120) is configured to: permute the plurality of bits of the padded encoded bit sequence and a respective plurality of bits of each of the N-l further padded encoded bit sequences for obtaining a plurality of permuted padded encoded bit sequences; and generate, based on the plurality of permuted padded encoded bit sequences, a plurality of quadrature-amplitude modulation, QAM, symbols for generating the modulated data.

5. The wireless transmitter station (110; 120) of claim 4, wherein the wireless transmitter station (110; 120) is configured to permute the plurality of bits of the padded encoded bit sequence and the respective plurality of bits of each of the N-l further padded encoded bit sequences for obtaining the plurality of permuted padded encoded bit sequences using a binary convolutional code, BCC, interleaver (410).

6. The wireless transmitter station (110; 120) of any one of the preceding claims, wherein the wireless transmitter station (110; 120) is further configured to transmit information to the wireless receiver station (120; 110) indicative of the number of tones of the RU defined by the IEEE 802.11 framework of standards and / or the number of tones of the further RU defined by the IEEE 802.11 framework of standards for the channel bandwidth.

7. The wireless transmitter station (110; 120) of any one of the preceding claims, wherein the wireless transmitter station (110; 120) is further configured to transmit information, in particular a flag bit, to the wireless receiver station (120; 110) indicative of whether the wireless transmitter station (110; 120) is operating in the replication mode.

8. The wireless transmitter station (110; 120) of any one of the preceding claims, wherein the plurality of tones of the RU comprises a plurality of data tones and a plurality of Carrier Frequency Offset, CFO, pilot tones and wherein the plurality of tones of the further RU comprises a plurality of further data tones and a plurality of further CFO pilot tones.

9. The wireless transmitter station (110; 120) of any one of the preceding claims, wherein the wireless transmitter station is configured to transmit the modulated data to the wireless receiver station (120; 110) as part of a data payload of a physical protocol data unit, PPDU.

10. The wireless transmitter station (110; 120) of claim 9, wherein the content and tone allocation of a short training field, STF, or long training field, LTF, within a PHY preamble of the PPDU is based on the size and tone allocation of the further RU as defined by the IEEE 802.11 framework of standards.

11. The wireless transmitter station (110; 120) of claim 9, wherein the content and tone allocation of each of a plurality of short training fields, STFs, or long training fields, LTFs, within a PHY preamble of the PPDU for each component RU of the further RU is based on the size and tone allocation of an RU with K tones as defined by the IEEE 802.11 framework of standards.

12. A method (700) for transmitting a bit sequence to a wireless receiver station (120;110) over a channel (130) with a channel bandwidth using Orthogonal Frequency Division Multiplexing, OFDM, or Orthogonal Frequency Division Multiple Access, OFDMA, communication, wherein the method (700) comprises: encoding (701) the bit sequence using a forward error correction, FEC, encoder (405) for obtaining an encoded bit sequence and padding the encoded bit sequence with post-FEC padding bits for obtaining a padded encoded bit sequence, wherein the number of bits of the padded encoded bit sequence is set for modulation over K tones of a resource unit, RU, defined by the IEEE 802.11 framework of standards; generating (703), based on the plurality of bits of the padded encoded bit sequence, N-l further padded encoded bit sequences, wherein N is an integer greater than 1 and wherein the number of bits of each of the N-l further padded encoded bit sequences is equal to the number of bits of the padded encoded bit sequence;applying (705) a modulation and permutation operation to the padded encoded bit sequence and the N-l further padded encoded bit sequences for generating modulated data; and transmitting (707) the modulated data to the wireless receiver station (120; 110) over a further RU with N*K+d tones, wherein the further RU comprises N component RUs of size K and wherein d denotes an integer larger than or equal to 0 and wherein the further RU is an RU as defined by the IEEE 802.11 framework of standards for the channel bandwidth.

13. A wireless transmitter station (110; 120) for transmitting a bit sequence to a wireless receiver station (120; 110) over a channel (130) with a channel bandwidth using Orthogonal Frequency Division Multiplexing, OFDM, or Orthogonal Frequency Division Multiple Access, OFDMA, communication, wherein in a replication mode the wireless transmitter station (110; 120) is configured to: encode the bit sequence using a forward error correction, FEC, encoder (405) for obtaining an encoded bit sequence and pad the encoded bit sequence with post-FEC padding bits for obtaining a padded encoded bit sequence; generate, based on the plurality of bits of the padded encoded bit sequence, a first set of quadrature-amplitude modulation, QAM, symbols for obtaining a first modulated data set using a first modulation operation, and generate, based on the plurality of bits of the padded encoded bit sequence, N-l further sets of QAM symbols for obtaining N-l further modulated data sets using N-l further modulation operations, wherein N is an integer greater than 1 and wherein each modulated data set of the first modulated data set and the N-l further modulated data sets defines modulated data for a respective component resource unit, RU, of a plurality of component RUs, wherein the number of tones of each component RU is equal to K and wherein K is the number of tones of a RU defined by the IEEE 802.11 framework of standards; apply low density parity code, LDPC, tone mapping of size K within each component RU; and transmit the modulated data to the wireless receiver station (120; 110) over an RU with N*K+d tones, wherein d is an integer larger than or equal to 0 and wherein N*K+d is the number of tones of a further RU defined by the IEEE 802.11 framework of standards for the channel bandwidth.

14. The wireless transmitter station (110; 120) of claim 13, wherein the wireless transmitter station (110; 120) is further configured to apply one or more predefined complex phase rotations to one or more segments of the first set of QAM symbols and / or the N-l further sets of QAM symbols for obtaining the first modulated data set and / or the N-l further modulated data sets.

15. The wireless transmitter station (110; 120) of any one of claims 13 or 14, wherein the wireless transmitter station (110; 120) is further configured to transmit information to the wireless receiver station (120; 110) indicative of the number of tones of the RU and / or the number of tones of the further RU defined by the IEEE 802.11 framework of standards for the channel bandwidth.

16. The wireless transmitter station (110; 120) of any one of claims 13 to 15, wherein the wireless transmitter station (110; 120) is further configured to transmit information to the wireless receiver station (120; 110) indicative of whether the wireless transmitter station (110; 120) is operating in the replication mode.

17. The wireless transmitter station (110; 120) of any one of claims 13 to 16, wherein the plurality of tones of each component RU comprises a plurality of data tones and a plurality of Carrier Frequency Offset, CFO, pilot tones and wherein the plurality of tones of the further RU comprises a plurality of further data tones and a plurality of further CFO pilot tones.

18. The wireless transmitter station (110; 120) of claim 17, wherein the number of the plurality of further CFO pilot tones of the further RU is equal to N times the number of CFO pilot tones of each component RU.

19. The wireless transmitter station (110; 120) of any one of claims 13 to 18, wherein the wireless transmitter station (110; 120) is configured to transmit the modulated data to the wireless receiver station (120; 110) as part of a data payload of a physical protocol data unit, PPDU.

20. The wireless transmitter station (110; 120) of claim 19, wherein the content and tone allocation of a short training field, STF, or long training field, LTF, within a PHY preamble of the PPDU is based on the size and tone allocation of the further RU as defined by the IEEE 802.11 framework of standards.

21. The wireless transmitter station (110; 120) of claim 19, wherein the content and tone allocation of a short training field, STF, or long training field, LTF, within a PHY preamble of the PPDU is based on the size and tone allocation of each component RU as defined by the IEEE 802.11 framework of standards.

22. A method (800) for transmitting a bit sequence to a wireless receiver station (120; 110) over a channel (130) with a channel bandwidth using Orthogonal Frequency Division Multiplexing, OFDM, or Orthogonal Frequency Division Multiple Access, OFDMA, communication, wherein the method (800) comprises: encoding (801) the bit sequence using a forward error correction, FEC, encoder (405) for obtaining an encoded bit sequence and padding the encoded bit sequence with post-FEC padding bits for obtaining a padded encoded bit sequence; generating (803), based on the plurality of bits of the padded encoded bit sequence, a first set of quadrature-amplitude modulation, QAM, symbols for obtaining a first modulated data set using a first modulation operation, and generating, based on the plurality of bits of the padded encoded bit sequence, N-l further sets of QAM symbols for obtaining N-l further modulated data sets using N-l further modulation operations, wherein N is an integer greater than 1 and wherein each modulated data set of the first modulated data set and the N-l further modulated data sets defines modulated data for a respective component resource unit, RU, of a plurality of component RUs, wherein the number of tones of each component RU is equal to K and wherein K is the number of tones of a RU defined by the IEEE 802.11 framework of standards; applying (805) low density parity code, LDPC, tone mapping of size K within each component RU; and transmitting (807) the modulated data to the wireless receiver station (120; 110) over an RU with N*K+d tones, wherein d is an integer larger than or equal to 0 and wherein N*K+d is the number of tones of a further RU defined by the IEEE 802.11 framework of standards for the channel bandwidth.

23. 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) ofclaim 12 or the method (800) of claim 22 when the program code is executed by the computer or the processor.

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