EP4690698A1 - A method for mitigating peak to average power ratio in a signal, a related transmitter device, and a related receiver device - Google Patents

Abstract

Disclosed is a method, performed by a transmitter device, for mitigating peak-to-average-power-ratio, PAPR, in a signal. The method comprises transmitting, to a receiver device, control signalling indicative of a fundamental set of a modulo operation for enabling the receiver device to determine the signal from a version of the signal modified for PAPR mitigation. The method comprises generating, based on the signal and the fundamental set, a set of PAPR mitigation parameters by solving an optimization problem. The method comprises generating the version of the signal based on the signal and the set of PAPR mitigation parameters. The method comprises transmitting the version of the signal to the receiver device.

Description

A METHOD FOR MITIGATING PEAK TO AVERAGE POWER RATIO IN A SIGNAL, A RELATED TRANSMITTER DEVICE, AND A RELATED RECEIVER DEVICE

The present disclosure pertains to the field of wireless communications. The present disclosure relates to a method for mitigating peak to average power ratio in a signal, a related transmitter device, and a related receiver device.

BACKGROUND

Multicarrier systems, such as Orthogonal frequency-division multiplexing, OFDM, systems, may suffer from high peak-to-average-power-ratio, PAPR. In other words, an OFDM signal may exhibit considerable amplitude fluctuations resulting in an increased PAPR. The increased PAPR may require power amplifiers, PAs, at a transmitter device with an extensive dynamical range, which can be problematic to build in hardware. Thus, the increased PAPR may force the PAs to operate at a power backoff (such as, in a linear region), implying that there is a degradation in the power efficiency of the PAs. In other words, the PAs may no longer be operating at its optimum power efficiency.

SUMMARY

Tone reservation, TR, techniques may mitigate PAPR of an OFDM signal at expense of a significant loss in data rate, as a number of OFDM subcarriers are reserved to carry PAPR mitigation signals. In addition, clipping techniques may mitigate PAPR of an OFDM signal at a cost of erroneous transmissions.

Accordingly, there is a need for devices and methods for PAPR mitigation in a signal, which may mitigate, alleviate or address the shortcomings existing and may provide a reduced computational complexity at a transmitter side, and no loss in data rate due to the PAPR mitigation. In other words, the disclosed techniques do not require additional resources to be reserved for dedicated PAPR mitigation signals.

Disclosed is a method, performed by a transmitter device, for mitigating peak-to-average-power- ratio, PAPR, in a signal. The method comprises transmitting, to a receiver device, control signalling indicative of a fundamental set of a modulo operation for enabling the receiver device to determine the signal from a version of the signal modified for PAPR mitigation. The method comprises determining, based on the signal and the fundamental set, a set of PAPR mitigation parameters, e.g. by solving an optimization problem. The method comprises generating the version of the signal based on the signal and the set of PAPR mitigation parameters. The method comprises transmitting the generated version of the signal to the receiver device. Further, a transmitter device comprising memory circuitry, processor circuitry, and a wireless interface is provided. The transmitter device is configured to perform any of the methods disclosed herein.

It is an advantage of the present disclosure that the disclosed transmitter device and related method allow for a reduced computational and hardware complexity at the transmitter side. The reduced complexity allows the technique to be implemented with a reduced practical complexity. Further, the transmitter device and related method enable a mitigation of the PAPR in the transmitted signal without negatively affecting the data rate. No additional resources need to be reserved for the transmission of the version of the signal modified for PAPR mitigation according to this disclosure. The transmitter device and related method can allow the generated version of the signal to be readily processed at a receiver device using a signal processing technique which is efficient (e.g. thanks to its limited complexity).

Disclosed is a method, performed by a receiver device, for receiving a signal which has been modified for peak-to-average-power-ratio, PAPR, mitigation at a transmitter device. The method comprises receiving, from the transmitter device, control signalling indicative of a fundamental set of a modulo operation for enabling the receiver device to determine the signal from a version of the signal modified for PAPR mitigation. The method comprises receiving, from the transmitter device, the version of the signal modified for PAPR mitigation. The method comprises determining the signal by applying the modulo operation to the version of the signal using the fundamental set.

Further, a receiver device comprising memory circuitry, processor circuitry, and a wireless interface is provided. The receiver device is configured to perform any of the methods disclosed herein.

It is an advantage of the present disclosure that the disclosed receiver device and related method does not increase hardware complexity at the receiver side. The modulo operation can be applied by the receiver without increasing complexity in hardware or in computation. Further, the receiver device and related method enable the transmitter device to mitigate the PAPR in the transmitted signal without negatively affecting the data rate. No additional resources need to be reserved for the transmission of the version of the signal modified for PAPR mitigation according to this disclosure. The receiver device and related method can allow the receiver device to efficiently process the signal based on the received version of the signal. BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present disclosure will become readily apparent to those skilled in the art by the following detailed description of examples thereof with reference to the attached drawings, in which:

Fig. 1 is a diagram illustrating an example wireless communication system comprising an example transmitter device and an example receiver device according to this disclosure, Fig. 2 is a flow-chart illustrating an example method, performed by a transmitter device, for mitigating peak-to-average-power-ratio in a signal according to this disclosure, Fig. 3 is a flow-chart illustrating an example method, performed by a receiver device, for receiving a signal which has been modified for peak-to-average-power-ratio mitigation according to this disclosure,

Fig. 4 shows a graph illustrating performance results of the disclosed technique,

Fig. 5 is a block diagram illustrating an example transmitter device according to this disclosure, and

Fig. 6 is a block diagram illustrating an example receiver device according to this disclosure.

DETAILED DESCRIPTION

Various examples and details are described hereinafter, with reference to the figures when relevant. It should be noted that the figures may or may not be drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the examples. They are not intended as an exhaustive description of the disclosure or as a limitation on the scope of the disclosure. In addition, an illustrated example needs not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular example is not necessarily limited to that example and can be practiced in any other examples even if not so illustrated, or if not so explicitly described.

The figures are schematic and simplified for clarity, and they merely show details which aid understanding the disclosure, while other details have been left out. Throughout, the same reference numerals are used for identical or corresponding parts.

A signal (such as an OFDM signal) may be seen as a signal transmitted over a plurality of subcarriers. A signal may comprise a set of subcarriers, with such subcarriers being used to carry one or more of: control information and user information.

In one or more examples, a signal (such as a transmitted discrete-time signal) can be expressed as s^f0) = Qx, where Q denotes an Inverse Discrete Fourier Transform, IDFT, matrix with dimension N x N, N denotes the number of subcarriers, and x denotes a vector of data symbols (such as, quadrature amplitude modulation, QAM, symbols) with dimension N x 1.

Since elements of the IDFT matrix Q may have a same magnitude and N may be typically large, the central-limit-theorem may be applicable which can imply that elements of the signal s⁽⁰⁾ may abide a complex Gaussian distribution. It may be noted that the Gaussian distribution exhibits poor PAPR. Put differently, the signal s^f0) may be likely to experience sporadic, but frequent, power spikes. The present disclosure may allow PAPR mitigation in the signal s⁽⁰⁾. The present disclosure provides techniques for manipulating the original data or symbols so that s⁽⁰⁾ is less spiky, e.g. by introducing a perturbation vector. The disclosed techniques have a reduced complexity which renders the techniques practical and readily implementable. The disclosed technique can be applied to any signal of a multi-carrier system.

Fig. 1 is a diagram illustrating an example wireless communication system 1 comprising an example transmitter device 300 and a receiver device 400 according to this disclosure.

As discussed in detail herein, the present disclosure relates to a wireless communication system 1 comprising a cellular system, for example, a 3GPP wireless communication system. The wireless communication system 1 may comprise one or more transmitter devices 300, 300A, and one or more receiver devices 400.

A transmitter device disclosed herein (such as, transmitter device 300) may refer to an electronic device configured to transmit, to a receiver device, the modified version of the signal as disclosed herein. A receiver device disclosed herein may refer to an electronic device configured to receive, from a transmitter device, the modified version of the signal as disclosed herein.

In one or more examples, the transmitter device 300 is a wireless device while the receiver device 400 is a network node. This is for example in uplink, UL, transmissions. In one or more examples, the transmitter device 300 is a network node while the receiver device 400 is a wireless device, such as in downlink, DL transmissions. The present disclosure may be applied to downlink, DL and/or uplink, UL, transmissions. A wireless device may be seen as a mobile device and/or a user equipment, UE. A network node disclosed herein may be seen as a radio access network, RAN, node operating in the RAN, such as one or more of: a base station, an evolved Node B, eNB, a next generation Node B, gNB, in New Radio, NR, and an access point, AP. In one or more examples, the RAN node is a functional unit which may be distributed in several physical units.

The transmitter device 300, 300A may be configured to communicate with the receiver device 400 via a wireless link (or radio access link) 10, 10A, respectively.

In one or more examples, the transmitter device is a first wireless device (such as, device 300) while the receiver device is a second wireless device (such as, device 300A). The present disclosure may involve sidelink, SL, transmissions. The first wireless device may be configured to communicate with the second wireless device via a wireless link (or radio access link) 12.

The wireless link can be seen as a communication channel and/or a radio channel.

The transmitter device 300 is configured to perform the methods disclosed herein for mitigating peak-to-average-power-ratio, PAPR, in a signal (such as in Fig. 2). The receiver device 400 is configured to perform the methods disclosed herein for receiving a signal which has been modified for peak-to-average-power-ratio, PAPR, mitigation at the transmitter device (such as in Fig. 3).

The transmitter device 300 may generate a signal by performing an IFFT on the signal x followed by addition of a cyclic prefix (CP) to the signal. Let y denote a received signal at the receiver device after the removal of the CP. The receiver device may apply a fast Fourier transform, FFT, to the received signal y to obtain a signal r which may be expressed as, r = Q^Hy = diag(h)x + w, (1) where diag(-) denotes a diagonal matrix with its argument along the main diagonal, and w denotes noise parameters. For example, the signal r at subcarrier n may be expressed as r_n = h_nx_n + w_n, with 1 < n < N and where x_n may be obtained from a constellation such that, for some arbitrary number B.

The present disclosure may enable generation of a version of the signal modified for PAPR mitigation, for example according to s = Q(x + Ap) where p denotes a set of PAPR mitigation parameter (such as a vector of Gaussian integers and/or scalars), and where A > B, and A establishes a range for a mapping of the received signal. In one or more examples, a PAPR mitigation parameter is in the form of a Gaussian integer, e.g. in the form of a + bi, where both a and b are integers. In one or more examples, the set of PAPR mitigation parameters may include one or more scalar elements. The set of Gaussian integers may be denoted as G. The signal r at subcarrier n may be expressed as,

In other words, for example, the signal r at subcarrier n is the received version of the signal s modified (at the transmitter) for PAPR mitigation.

In some examples, an equalization technique is applied to the signal r (such as, by compensating for h_n), resulting in an equalized signal at subcarrier n that may be expressed as z_n x_n -I- Ap_n “I- w_n/h_n.

The receiver device can obtain the signal for demodulation from r, the received version of the signal s modified (at the transmitter) for PAPR mitigation. For example, to obtain the signal for demodulation from r, the receiver device needs to cancel or remove Ap_n from z_n, prior to demodulating. In one or more examples, the signal for demodulation can be seen as a PAPR free signal and/or a PAPR compensated signal and/or a PAPR cancelled signal. The present disclosure proposes to apply, to the received signal, a modulo operation parametrized with a fundamental set that has been communicated from the transmitter device to the receiver device via control signalling.

Let A denote a fundamental set associated with the modulo operation for enabling the receiver device to determine the signal from the version of the signal modified for PAPR mitigation. In other words, the fundamental set may be seen as a parameter of the modulo operation, such as a divisor of the modulo operation. In some examples, the term “fundamental set” and “divisor” may be used interchangeably. In one or more examples, the fundamental set can be based on a Voronoi cell. In one or more examples, the signal for demodulation can be seen as a remainder of the modulo operation. The fundamental set can be seen as modulo parameter.

The fundamental set may be expressed as: A = {c + di, —A < c, d < A}, where both c and d are real numbers. It may be appreciated that in some examples, A is to be larger than the amplitude of the modulation in order to be robust to noise. A margin parameter A_m may be applied to allow for A to be larger than the amplitude of the modulation, e.g. larger than B. In one or more examples, the fundamental set A may comprise a plurality of real numbers (such as, c and d) between —A and A. The fundamental set A may be indicative of any pairs of real numbers (such as, a pair (c, d)) where each number does not exceed a range [-A,A] based on a margin parameter A_m in magnitude. The range can be seen as a 2D range.

In one or more examples, the fundamental set A may be determined based on a transmit power applied for transmitting the modified version of the signal carrying the vector of data symbols x. There may be different transmit power applied for different constellations of the modulation schemes. For example, the fundamental set A is larger when the vector of data symbols x is associated with a higher transmit power. For example, the fundamental set A is smaller when the vector of data symbols x is associated with a lower transmit power. In one or more examples, the fundamental set A is configured to allow a mapping to a constellation to which an input bit stream (such as, comprising information bits) is mapped (such as, based on a modulation scheme) for provision of the data symbols x. For example, the margin parameter A_m may be indicative of a margin applied to a point associated with a space delimitating the constellation allowing determination of the fundamental set A.

Applying a modulo operation to the received signal, such as to the equalized received signal z_n using the set A (such as, by determining z_n modulo A) may yield to the following signal for demodulation, e.g.: z_n mod mod

It may be appreciated that the modulo operation based on A allows removing p (for example by removing Ap_n from z_n ) which was introduced for PAPR mitigation. The result of the modulo operation can then be used to demodulate for obtaining x_n.

In one or more examples, the fundamental set A allows an element of a result of the modulo operation mod to fall in a range of [-A, A], The fundamental set A may enable the receiver device to properly and readily demodulate the data symbols x. In other words, the receiver device may be able to determine the data symbols x by demodulating the result of applying the modulo operation to the equalized signal z_n using the fundamental set A. Stated differently, the result of the modulo operation is the signal for demodulation, such as to be demodulated by the receiver device.

The present disclosure may allow PAPR mitigation in the signal s⁽⁰⁾ by generating a version s of the signal modified for PAPR mitigation and by enabling, at the receiver device, removal of the set of PAPR mitigation parameters (such as the vector of Gaussian integers) p from the received version of the signal modified for PAPR mitigation. The receiver device may be able to demodulate x_n without any additional cost (e.g. without additional operation, without a modified demodulation, without dedicated hardware).

The present disclosure may provide a technique for modifying the signal s⁽⁰⁾ for PAPR mitigation in such a way that the receiver device receiving the modified signal can remove a part of the modified signal introduced for PAPR performance.

In one or more examples, the transmitter device is configured to generate the set of PAPR parameters, such as the vector of Gaussian integers, p for suppressing PAPR in the signal s. The transmitter device may generate the set of PAPR parameters, such as the vector of Gaussian integers, p by solving an optimization problem for minimizing one or more maximum peaks of the signal s⁽⁰⁾. The optimization problem may be expressed as, p = arg where q_n denotes the n:th row of the IFFT matrix Q and t_n denotes a candidate PAPR mitigation parameter for the signal s⁽⁰⁾. The set of PAPR mitigation parameter, so called vector of Gaussian integers, p may be seen as an optimum vector for enabling PAPR mitigation in the signal s⁽⁰⁾. It may be noted that such optimization problem may be of exponential complexity in N. The present disclosure solves the optimization problem in a practical implementation for practical values of N.

The present disclosure may provide a technique to generate the set of PAPR parameters, such as the vector of Gaussian integers, p, while involving a low computational complexity and yielding satisfactory performance results in terms of PAPR reduction.

It is noted that the signal s⁽⁰⁾ = Qx (such as, a signal before modification for PAPR mitigation). The transmitter device may generate a set of PAPR mitigation parameters (such as, the vector of Gaussian integers p) e.g. by one or more of the following steps:

Step 1. Determining one or more peaks of the signal s⁽⁰⁾. In other words, the transmitter device may search for M elements in the signal s⁽⁰⁾ having the largest magnitude;

Step 2. Setting each peak of the signal s⁽⁰⁾ to a zero value. Put differently, the transmitter may replace each of the M elements by a zero value for provision of a first signal

Step 3. Transforming the first signal into a second signal s⁽²⁾ by letting s⁽²⁾ In other words, the second signal s⁽²⁾ may be seen as a vector with a same magnitude as first signal but pointing in an opposite direction, such as an opposite of s⁽¹⁾and/or an additive inverse

Step 4. Generating and/or determining an initial set of PAPR mitigation parameters, which may be illustrated

Step 5. Generating and/or determining the set of PAPR mitigation parameters, such as vector p, by approximating (such as, rounding) elements of the initial set, such as vector p to the closest elements in GQ4), where GQ4) = {Ap p e G}. In one or more examples, G(A) is a set of scaled Gaussian integers. For example, the elements of the initial set, such as vector p, may be rounded up or rounded down to the closest integer in G(A).

In one or more examples, the transmitter device generates a version of the signal s based on the signal s⁽⁰⁾ and the set of PAPR mitigation parameters, wherein the version s is modified for PAPR mitigation. The version s of the signal s⁽⁰⁾ may be expressed as: s = Q(x + Ap) (5)

In one or more examples, transforming signal into a signal s⁽²⁾ (such as, in Step 3) can be seen as transmitting approximately —Qx, in each M elements are replaced by a zero value. It may be appreciated that the opposite or additive inverse is generated for transmission to provide a signal that is as far away as possible from the intended signal Qx to enable a nonzero vector of p to be applied at the transmitter device and to be removed at the receiver device. In some examples, the non-zero entries in signal p needs to be larger than those in x to enable the receiver device to remove the non-zero entries without any impact on x . This may allow an efficient application of the modulo operation for eliminating the part of the version of the signal that is modified for PAPR mitigation.

The PAPR mitigation techniques disclosed herein provide a reduction in computational complexity as the computational complexity may be limited to a search for the M largest elements (such as, one or more peaks, such as peaks in power and/or amplitudes), and an additional FFT operation in Step 4. It may be appreciated that the search for the peaks has a complexity linear with N and the additional FFT has a complexity of /Vlog(/V) which is considered negligible.

In an example where the disclosed technique is applied, let N = 8, M = 1, where Q is normalized such that QQ^U = I, let x denote QPSK symbols and x^T = [1 — i — 1 + i — 1 — i 1 + i — 1 + i — 1 — i — 1 + i — 1 — t]. The transmitted signal s⁽⁰⁾ = Qx before modification for PAPR mitigation may be expressed as e.g.:

- 1.4142

- 0.0858 - 0.2071/

0.7071 - 0.7071/ 0.5000 - 0.2071/

0

2.9142 - 1.2071/

0.7071 + 0.7071/

0.5000 - 1.2071/

The signals and s⁽²⁾ become for example:

- 1.4142 + 0.0000/ 1.4142

- 0.0858 - 0.2071/ 0.0858 + 0.2071/ 0.7071 - 0.7071/ - 0.7071 + 0.7071/ 0.5000 - 0.2071/ . m 0.5000 + 0.2071/ and s^[Z) =

0

0 0 0.7071 + 0.7071/ - 0.7071 - 0.7071/ 0.5000 - 1.2071/ - 0.5000 + 1.2071/

Calculating the initial set of PAPR parameters p = Q^H(s® - gives for example:

- 0.9697 + 1.5732/

1.5732 - 0.9697/

1.5732 + 0.9697/

~ ₌ - 0.9697 - 1.5732/

^P 0.9697 - 1.5732/

2.4268 + 0.9697/

2.4268 - 0.9697/

0.9697 + 1.5732/ and using A = 2, gives after approximation (such as quantization) to G(2) for example:

1.0000/

1.0000

1.0000

- 1.0000/

- 1.0000/

1.0000

1.0000

1.0000/ The transmitted signal may become expressed as:

1.4142

0.9141 + 2.2071/ -0.7071 + 0.7071/ nr 0 + 0.2071/

Q(x + Ap) = .5 _Q000

1.9142 - 0.7929/ -0.7071 - 0.7071/ -0.5000 + 1.2071/

It may be appreciated to compare the two signals Q(x + Ap) and s⁽⁰⁾ = Qx where s⁽⁰⁾ is the signal without applying the disclosed technique while Q(x + Ap) is the transmitted signal modified by applying the disclosed technique. However, in the example, the peak power is ~ 9.95 without the disclosed technique and ® 5.71 with the disclosed technique. The example shows that the PAPR is reduced from ® 4.97 to ~ 2.85 (e.g., 2.41 dB reduction).

Fig. 2 shows a flow-chart of an example method 100, performed by a transmitter device according to the disclosure, for mitigating peak-to-average-power-ratio, PAPR, in a signal. The transmitter device is the transmitter device 300 of Fig. 1 and Fig. 5. In one or more examples, the signal comprises one or more of: control data and user data. In other words, the signal being mitigated for PAPR is a signal to be transmitted by the transmitter device. In other words, the signal can be seen as an original signal (e.g. including original data symbols) before modification for PAPR reduction.

The method 100 comprises communicating S102, between the transmitter device and a receiver device, control signalling indicative of a fundamental set (such as, fundamental set A) of a modulo operation. The modulo operation is for enabling the receiver device to determine the signal (such as signal s⁽⁰⁾) from a version of the signal (such as, version of signal s) modified for PAPR mitigation.

The modification of the signal (e.g., original signal) can be seen as a manipulation of the signal to reduce spikes and/or peaks before transmission. In some examples, the signal is modified using a perturbation vector that is based on a set of PAPR mitigation parameters which is configured with (e.g., to work with) the modulo operation and the fundamental set.

In one or more examples, the version of the signal can be seen as a signal which has been modified for PAPR mitigation at the transmitter device and enables the receiver device to eliminate the modifications introduced by the transmitter device to reduce PAPR. In one or more examples, the version s of the signal can be seen as a signal which has been modified for PAPR mitigation at the transmitter device, as illustrated in Equation 5.

It may be appreciated that for the transmitter device to apply the PAPR mitigation technique disclosed herein, the transmitter device communicates control signalling indicative of the PAPR mitigation technique disclosed herein that is based on the application of a set of PAPR mitigation parameter that can be removed by the receiver device using the modulo operation parameterized with the fundamental set (for example illustrated in Equation 3).

In other words, the fundamental set may be seen as a parameter of the modulo operation, such as a divisor of the modulo operation. In one or more examples, the fundamental set may be determined based on a transmit power applied for transmitting the modified version of the signal carrying the vector of data symbols. In one or more examples, the fundamental set is configured to allow a mapping to a constellation to which an input bit stream (such as, comprising information bits) is mapped (such as, based on a modulation scheme) for provision of the data symbols. It may be appreciated that the modulo operation based on the fundamental set allows removing, at the receiver device, the set of PAPR mitigation parameters which was introduced for PAPR mitigation. The result of the modulo operation can then be used as an input to the demodulation for obtaining the data symbols. The fundamental set and modulo operation may enable the receiver device to properly, efficiently and readily demodulate the data symbols. In other words, the receiver device may be able to determine the data symbols by demodulating the result of the modulo operation on the received signal using the fundamental set. Stated differently, the result of the modulo operation (e.g. the remainder of the modulo operation) is the signal for demodulation, such as to be demodulated by the receiver device, such as the PAPR free signal, and/or the PAPR-cancelled signal.

The control signalling advantageously allows the receiver device to prepare for receiving and processing the received version of the signal modified for PAPR mitigation to obtain the data symbols.

In one or more examples, the control signaling comprises a flag and/or one or more control messages indicative of the fundamental set of the modulo operation for enabling the receiver device to determine the signal from the version of the signal modified for PAPR mitigation.

In one or more example methods, communicating S102, between the transmitter device and the receiver device, the control signalling comprises transmitting S102A, to the receiver device, the control signalling. In one or more examples, the transmitter device is a network node while the receiver node is a wireless device, such as in a DL transmission. For example, the network node is configured to transmit, to the wireless device, the control signalling indicative of the fundamental set of the modulo operation. In other words, the network node may inform the wireless device about a reception of a signal which has been modified for PAPR mitigation at the network node, such as the version of the signal. Put differently, the network node may instruct (such as, configure, enable, and/or activate) the wireless device to apply the modulo operation to the version s of the signal using the fundamental set. For example, the network node is configured to transmit, to the wireless device, the control signalling indicative of the fundamental set of the modulo operation after receiving, from the wireless device, control signalling indicative of a capability to apply the fundamental set of the modulo operation to the version of the signal (such as, after S101). It may be appreciated that communication of the control signalling is performed between the transmitter device and the receiver device to enable the application of the disclosed PAPR mitigation techniques at the transmitter device and at the receiver device (e.g., for mutual awareness).

In one or more example methods, communicating S102, between the transmitter device and the receiver device, the control signalling comprises receiving S102B, from the receiver device, the control signalling. In one or more examples, the transmitter device is a wireless device while the receiver device is a network node, such as in an UL transmission. In one or more examples, the wireless device is configured to receive, from the network node, the control signalling of the fundamental set of the modulo operation to be applied by the network node for determining the signal from the version of the signal. Put differently, the network node may instruct (such as, configure, enable, and/or activate) the wireless device to use the fundamental set for generating the version of the signal. For example, the network node is configured to transmit, to the wireless device, the control signalling indicative of the fundamental set of the modulo operation after receiving, from the wireless device, control signalling indicative of a capability to generate, based on the fundamental set of the modulo operation, the version of the signal.

Optionally, the wireless device is configured to transmit, to the network node, an indication indicating that the wireless device is to modify the signal for PAPR mitigation. The indication may be indicative of an applied power backoff in a power amplifier of the wireless device. In one or more examples, the wireless device is configured to transmit, to the network node, capability signalling indicative of a capability to modify the signal for PAPR mitigation. In one or more examples, the capability signalling may comprise such indication. The network node may be configured to transmit, to the wireless device, based on the capability signalling and/or the indication, the control signalling indicative of the fundamental set of the modulo operation to be used by the network node for determining the signal from the version of the signal modified by the wireless device for PAPR mitigation. In other words, the network node may inform the wireless device about the fundamental set of the modulo operation to be used by the wireless device for generating the version of the signal.

In one or more examples, the transmitter device is a first wireless device (such as, wireless device 300) while the receiver device is a second wireless device (such as, wireless device 300A). The present disclosure may involve sidelink, SL, transmissions. In one or more examples, the first wireless device is configured to transmit, to the second wireless device, the control signalling indicative of a fundamental set of a modulo operation for enabling the second wireless device to determine the signal from a version of the signal modified for PAPR mitigation. Stated differently, the first wireless device may be configured to instruct the second wireless device to determine the signal by applying the modulo operation to the version of the signal using the fundamental set. In one or more examples, the first wireless device is configured to transmit, to the wireless device, the control signalling indicative of the fundamental set of the modulo operation after receiving, from the second wireless device, control signalling indicative of a capability to apply the fundamental set of the modulo operation to the version of the signal (such as, after S101).

The method 100 comprises determining S104, based on the signal and the fundamental set, a set of PAPR mitigation parameters (such as, the vector of Gaussian integers p) by solving S104A an optimization problem. Stated differently, the set of PAPR mitigation parameters is for example derived based on the signal (e.g. original signal) and the fundamental set associated with the modulo operation indicated in the control signalling. In one or more examples, the optimization problem can be illustrated by Equation 4. In one or more examples, the set of PAPR mitigation parameters resulting from solving the optimization problem can be seen as an optimum set of PAPR mitigation parameters for enabling PAPR mitigation in the signal.

The method 100 comprises generating S106, based on the signal and the set of PAPR mitigation parameters, the version of the signal. In one or more examples, the version of the signal (such as, version of signal s) may be illustrated by Equation 5. In one or more examples, the version of the signal is modified using the set of PAPR mitigation parameters for a reduced PAPR (such as, a PAPR mitigated signal).

The method 100 comprises transmitting S108 the generated version of the signal to the receiver device. In one or more examples, the transmitter device is configured to transmit, to the receiver device, the version s of the signal. It may be appreciated that the transmitted version of the signal is generated such that the PAPR is reduced, and the receiver is capable of removing the modified aspects of the version of the signal received for demodulating the actual data symbols. In other words, the receiver device is configured to receive, from the receiver device, the version s of the signal. The receiver device may be configured to determine a signal for demodulation based on the version s of the signal.

In one or more example methods, solving S104A the optimization problem comprises minimizing S104AA one or more maximum peaks of the signal. For example, the one or more maximum peaks may be seen as one or more peaks in power and/or in amplitude. In one or more examples, minimizing one or more maximum peaks of the signal comprises minimizing one or more peaks in power and/or in amplitude. In one or more examples, the transmitter device is configured to determine the optimum set of PAPR mitigation parameters by minimizing the one or more maximum peaks of the signal. It may be noted that in some instances, the optimization problem is of exponentially complexity. However, the optimization problem may be solved to some extent for a practical implementation for wireless communication systems (such as, practical communication systems). In one or more examples, computational complexity at the transmitter may substantially increase when solving the optimization problem.

The present disclosure may allow determining the set of PAPR mitigation parameters with a reduced complexity and increased practicality. The transmitter device may benefit from a reduced computational complexity while enabling a satisfactory PAPR mitigation of the signal. In one or more example methods, determining S104 the set of PAPR mitigation parameters comprises determining S104B one or more peaks of the signal. In one or more examples, determining the one or more peaks of the signal comprises searching for M elements in the signal s⁽⁰⁾ having the largest magnitude (as illustrated in Step 1 ).

In one or more example methods, determining S104 the set of PAPR mitigation parameters comprises setting S104C each peak to a zero value for provision of a first signal (such as, signal of Step 2). In one or more examples, setting each peak to a zero value comprises replacing each of the M elements by a zero value for provision of the first signal (such as as illustrated in Step 2). In one or more example methods, determining S104 the set of PAPR mitigation parameters comprises determining S104D, based on the first signal (such as, first signal s⁽¹⁾), a second signal (such as, second signal s⁽²⁾ of Step 3). The second signal is a transformed representation of the first signal (such as, s⁽²⁾ = The second signal may be a negative representation of the first signal (such as an opposite of s^{fl )}and/or an additive inverse of s⁽¹⁾). The second signal may be seen as the first signal multiplied by “-1”. The second signal may be symmetric to the first signal with respect to an origin. Stated differently, the second signal may be seen as a vector with a same magnitude as the signal but pointing in an opposite direction. In one or more example methods, determining S104 the set of PAPR mitigation parameters comprises determining S104E, based on the signal (such as, signal s⁽⁰⁾) and the second signal (such as, signal s⁽²⁾ of Step 3), the set of PAPR mitigation parameters (such as, an initial set of PAPR mitigation parameters, such as vector p of Step 4, with p = Q^H(s⁽²⁾ - s⁽⁰⁾)). In one or more examples, generating the set of PAPR mitigation parameters corresponds to Step 4.

In one or more example methods, determining S104 the set of PAPR mitigation parameters comprises approximating (such as, rounding, quantizing) S104F, based on the fundamental set (such as, fundamental set A), one or more elements of the set of PAPR mitigation parameters (such as, vector p of Step 5). In one or more examples, approximating the one or more elements of the set of PAPR mitigation parameters corresponds to Step 5. In one or more examples, the transmitter node may generate the set of PAPR mitigation parameters by approximating one or more elements of the initial set of PAPR mitigation parameters. In one or more examples, the transmitter is configured to approximate the one or more elements of the initial set of PAPR mitigation parameters by rounding up or rounding down the one or more elements (such as, real numbers) to closest integers in G(A).

In one or more example methods, the fundamental set (such as, fundamental set A = e [-A,A]}) is indicative of a range (such as, a 2D range [-A,A]) determined based on a margin parameter (such as, margin parameter A_m, where the margin parameter satisfies A = A_m + B). In one or more examples, the range of the fundamental set may be determined based on a transmit power associated with the signal. In other words, the range of the fundamental set may be associated with a modulation scheme.

In one or more example methods, the control signalling comprises information indicative of the fundamental set of the modulo operation. In one or more examples, the control signalling may comprise information about the fundamental set, such as the range of the fundamental set and/or the margin parameter. In some examples, some tuning for the fundamental set can be applied by setting A. In other words, the tuning can be controlled by setting A.

In one or more example methods, the control signalling comprises capability signalling indicative of a capability of the transmitter device to modify the signal for PAPR mitigation. In one or more examples, the capability signalling can be indicative of a capability of the transmitter device to apply the set of PAPR mitigation parameters for generating the modified version of the signal.

In one or more example methods, the control signalling comprises an activation indication to activate the PAPR mitigation using the set of PAPR mitigation parameters. In one or more examples, the control signalling can be carried out at Physical layer and/or at Link layer (such as, Medium Access Control, MAC layer and/or Radio Resource Control, RRC, layer). In one or more examples, the control signalling can be transmitted via Downlink Control Information, DCL In one or more examples, the PAPR mitigation using the set of PAPR mitigation parameters may be activated when a transmit power of the signal is beyond a threshold.

In one or more example methods, the control signalling comprises a flag indicating the fundamental set of the modulo operation. In one or more examples, the flag can be seen as implicit signalling of the fundamental set of the modulo operation. In other words, the flag may be seen as an implicit indication of the fundamental set of the modulo operation. In one or more examples, the flag indicating the fundamental set of the modulo operation can be activated for a given release and/or for a certain frequency range (such as, at sub THz). In one or more examples, the control signalling comprises one or more control messages. The one or more control messages can indicate to the receiver device the fundamental set of the modulo.

In one or more example methods, the method 100 comprises receiving S101 , from the receiver device, control signalling indicative of a capability of the receiver device to apply the modulo operation to the version of the signal. In one or more examples, the control signalling indicates a capability according to which the receiver device is capable of applying the modulo operation to the version of the signal. In some examples, the control signalling indicative of the disclosed capability of the receiver device may be in form of a flag and/or one or more control messages indicative of the disclosed capability of the receiver device.

Fig. 3 shows a flow-chart of an example method 200, performed by a receiver device according to the disclosure, for receiving a signal which has been modified for peak-to-average-power- ratio, PAPR, mitigation at a transmitter device. The receiver device is the receiver device disclosed herein, such as receiver device 400 of Fig. 1 and Fig. 6.

The method 200 comprises communicating S202, between the transmitter device and the receiver device, control signalling indicative of a fundamental set of a modulo operation for enabling the receiver device to determine the signal from a version of the signal modified for PAPR mitigation. In one or more examples, this may correspond to S102 of Fig. 2. The method 200 comprises receiving S204, from the transmitter device, a version of the signal modified for PAPR mitigation. In one or more examples, the receiver node receives the version of the signal modified for PAPR mitigation transmitted in S108 of Fig. 2.

The method 100 comprises determining S206 the signal by applying S206A the modulo operation to the version of the signal using the fundamental set (e.g. illustrated in Equation 3).

In one or more example methods, the method 200 comprises applying S205 an equalisation technique to the version of the signal for provision of an equalised signal (such as, equalized signal z_n). In one or more examples, the equalization technique can comprise one or more of: a zero forcing, ZF, a Minimum Mean Square Error, MMSE, a matched filter, MF, and any other suitable equalization technique. In one or more example methods, applying S206A the modulo operation to the version of the signal comprises applying S206AA the modulo operation to the equalised signal using the fundamental set. In one or more examples, applying the modulo operation to the equalised signal using the fundamental set can be seen as mapping a symbol of the equalized signal to a corresponding constellation point of the fundamental set.

In one or more example methods, applying S206A the modulo operation to the version of the signal comprises removing S206AB a set of PAPR mitigation parameters from the version of the signal, such as the received version of the signal. In one or more examples, the transmitter device generates the version of the signal based on the signal and the set of PAPR mitigation parameters, which is transmitted in S108 of Fig. 2 and received by the receiver device in S204. In one or more examples, the version of the signal comprises the set of PAPR mitigation parameters (such as, as illustrated in Equation 5). In one or more examples, removing the set of PAPR mitigation parameters from the signal may be illustrated by Equation 3.

In one or more example methods, wherein communicating S202, between the receiver and the transmitter device, the control signalling comprises receiving S202A, from the transmitter device, the control signalling. In one or more examples, the receiver node receives the control signalling transmitted in S102A of Fig. 2, for example in a DL communication.

In one or more example methods, wherein communicating S202, between the transmitter device and the receiver device, the control signalling comprises transmitting S202B, to the transmitter device, the control signalling. In one or more examples, the receiver node receives the control signalling transmitted in S102B of Fig. 2, for example in a UL communication. In one or more example methods, the control signalling comprises information indicative of the fundamental set of the modulo operation. In one or more example methods, the control signalling comprises capability signalling indicative of a capability of the transmitter device to apply the set of PAPR mitigation parameters. In one or more example methods, the control signalling comprises an activation indication to activate the PAPR mitigation using the set of PAPR mitigation parameters.

In one or more example methods, the control signalling comprises a flag indicating the fundamental set of the modulo operation.

In one or more example methods, the method 200 comprises transmitting S201 , to the transmitter device, control signalling indicative of a capability of the receiver device to apply the modulo operation to the version of the signal. In one or more examples, the receiver node transmits the control signalling indicative of a capability of the receiver device to apply the modulo operation to the version of the signal received in S101 of Fig. 2.

Fig. 4 shows a graph 500 illustrating performance results of the disclosed technique.

Fig. 4 shows a probability that a PAPR of a signal exceeds a threshold, which is a factor times an average power. In other words, the graph 500 illustrates a probability that an envelope associated with a signal exceeds a factor times an average power.

The numerical results of Fig. 4 are provided for the case N=128. The graph 500 shows the results for no PAPR mitigation and for various values of M. Fig. 4 can help to determine which M provide the best performance. The value E of Fig. 4 represents the mean power of the signal. Fig. 4 shows PAPR reduction results. Graph 500 plots the probability that the envelope of the signal exceeds a factor K times the average power E. Fig. 4 shows that the best performance is obtained for M=7. Increasing M (far) beyond 7 yields inferior performance.

Fig. 5 shows a block diagram of an example transmitter device 300 according to the disclosure. The transmitter device 300 comprises memory circuitry 301 , processor circuitry 302, and a wireless interface 303. The transmitter device 300 may be configured to perform any of the methods disclosed in Fig. 2. In other words, the transmitter device 300 may be configured to mitigate PAPR in a signal.

The transmitter device 300 is configured to communicate with receiver device, such as the receiver device disclosed herein, using a wireless communication system. The transmitter device 300 is configured to communicate (such as, via the wireless interface 303), between the transmitter device and the receiver device, control signalling indicative of a fundamental set of a modulo operation for enabling the receiver device to determine the signal from a version of the signal modified for PAPR mitigation.

The transmitter device 300 is configured to generate (such as, via the processor circuitry 302) based on the signal and the fundamental set, a set of PAPR mitigation parameters by solving an optimization problem.

The transmitter device 300 is configured to generate (such as, via the processor circuitry 302) the version of the signal based on the signal and the set of PAPR mitigation parameters.

The transmitter device 300 is configured to transmit (such as, via the wireless interface 303), to the receiver device, the version of the signal.

The wireless interface 303 is configured for wireless communications via a wireless communication system, such as a 3GPP system, such as a 3GPP system supporting one or more of: New Radio, NR, Long Term Evolution, LTE, Narrow-band loT, NB-loT, and Long Term Evolution - enhanced Machine Type Communication, LTE-M, and 3GPP system operated in licensed bands or unlicensed bands.

Processor circuitry 302 is optionally configured to perform any of the operations disclosed in Fig. 2 (such as any one or more of: S101 , S102, S102A, S102B, S104, S104A, S104AA, S104B, S104C, S104D, S104E, S104F, S106, S108). The operations of the transmitter device 300 may be embodied in the form of executable logic routines (for example, lines of code, software programs, etc.) that are stored on a non-transitory computer readable medium (for example, memory circuitry 301 ) and are executed by processor circuitry 302.

Furthermore, the operations of the transmitter device 300 may be considered a method that the transmitter device 300 is configured to carry out. Also, while the described functions and operations may be implemented in software, such functionality may also be carried out via dedicated hardware or firmware, or some combination of hardware, firmware and/or software. Memory circuitry 301 may be one or more of: a buffer, a flash memory, a hard drive, a removable media, a volatile memory, a non-volatile memory, a random access memory, RAM, and any other suitable device. In a typical arrangement, memory circuitry 301 may include a non-volatile memory for long term data storage and a volatile memory that functions as system memory for processor circuitry 302. Memory circuitry 301 may exchange data with processor circuitry 302 over a data bus. Control lines and an address bus between memory circuitry 301 and processor circuitry 302 also may be present (not shown in Fig. 5). Memory circuitry 301 is considered a non-transitory computer readable medium.

Memory circuitry 301 may be configured to store the control signalling, the set of PAPR mitigation parameters, the version of the signal in a part of the memory.

Fig. 6 shows a block diagram of an example receiver device 400 according to the disclosure. The receiver device 400 comprises memory circuitry 401 , processor circuitry 402, and a wireless interface 403. The receiver device 400 may be configured to perform any of the methods disclosed in Fig. 3. In other words, the receiver device 400 may be configured to receive a signal which has been modified for PAPR mitigation at a transmitter device.

The receiver device 400 is configured to communicate with a transmitter device, such as the transmitter device disclosed herein, using a wireless communication system.

The receiver device 400 is configured to receive (such as, via the wireless interface 403), from the transmitter device, control signalling indicative of a fundamental set of a modulo operation for enabling the receiver device to determine the signal from a version of the signal modified for PAPR mitigation.

The receiver device 400 is configured to communicate (such as, via the wireless interface 403), between the receiver device and the transmitter device, a version of the signal modified for PAPR mitigation.

The receiver device 400 is configured to determine (such as, via the processor circuitry 402) the signal by applying the modulo operation to the version of the signal using the fundamental set.

The wireless interface 403 is configured for wireless communications via a wireless communication system, such as a 3GPP system, such as a 3GPP system supporting one or more of: New Radio, NR, Long Term Evolution, LTE, Narrow-band loT, NB-loT, and Long Term Evolution - enhanced Machine Type Communication, LTE-M, and 3GPP system operated in licensed bands or unlicensed bands.

The receiver device 400 is optionally configured to perform any of the operations disclosed in Fig. 3 (such as any one or more of: S201 , S202, S202A, S202B, S204, S205, S206, S206A, S206AA, S206AB). The operations of the receiver device 400 may be embodied in the form of executable logic routines (for example, lines of code, software programs, etc.) that are stored on a non-transitory computer readable medium (for example, memory circuitry 401 ) and are executed by processor circuitry 402.

Furthermore, the operations of the receiver device 300 may be considered a method that the receiver device 400 is configured to carry out. Also, while the described functions and operations may be implemented in software, such functionality may also be carried out via dedicated hardware or firmware, or some combination of hardware, firmware and/or software. Memory circuitry 401 may be one or more of: a buffer, a flash memory, a hard drive, a removable media, a volatile memory, a non-volatile memory, a random access memory, RAM, and any other suitable device. In a typical arrangement, memory circuitry 301 may include a non-volatile memory for long term data storage and a volatile memory that functions as system memory for processor circuitry 402. Memory circuitry 401 may exchange data with processor circuitry 402 over a data bus. Control lines and an address bus between memory circuitry 301 and processor circuitry 402 also may be present (not shown in Fig. 6). Memory circuitry 301 is considered a non-transitory computer readable medium.

Memory circuitry 401 may be configured to store the control signalling, the version of the signal, the signal in a part of the memory.

Examples of methods and products (transmitter device and receiver device) according to the disclosure are set out in the following items:

Item 1 . A method, performed by a transmitter device, for mitigating peak-to-average-power- ratio, PAPR, in a signal, the method comprising: communicating (S102), between the transmitter device and a receiver device, control signalling indicative of a fundamental set of a modulo operation for enabling the receiver device to determine the signal from a version of the signal modified for PAPR mitigation; determining (S104), based on the signal and the fundamental set, a set of PAPR mitigation parameters by solving (S104A) an optimization problem;

- generating (S106) the version of the signal based on the signal and the set of PAPR mitigation parameters; and

- transmitting (S108) the generated version of the signal to the receiver device.

Item 2. The method according to item 1 , wherein solving (S104A) the optimization problem comprises minimizing (S104AA) one or more maximum peaks of the first signal. Item 3. The method according to any of the previous items, wherein determining (S104) the set of PAPR mitigation parameters comprises: determining (S104B) one or more peaks of the signal; setting (S104C) each peak to a zero value for provision of a first signal; determining (S104D), based on the first primary signal, a second signal, wherein the second signal is a transformed representation of the first signal; and determining (S104E), based on the signal and the second signal, the set of PAPR mitigation parameters.

Item 4. The method according to item 3, wherein determining (S104) the set of PAPR mitigation parameters comprises approximating (S104F), based on the fundamental set, one or more elements of the set of PAPR mitigation parameters.

Item 5. The method according to any of the previous items, wherein communicating (S102), between the transmitter device and the receiver device, the control signalling comprises transmitting (S102A), to the receiver device, the control signalling.

Item 6. The method according to any of the previous items, wherein communicating (S102), between the transmitter device and the receiver device, the control signalling comprises receiving (S102B), from the receiver device, the control signalling.

Item 7. The method according to any of the previous items, wherein the control signalling comprises information indicative of the fundamental set of the modulo operation.

Item 8. The method according to any of the previous items, wherein the control signalling comprises capability signalling indicative of a capability of the transmitter device to modify the signal for PAPR mitigation.

Item 9. The method according to any of the previous items, wherein the control signalling comprises an activation indication to activate the PAPR mitigation using the set of PAPR mitigation parameters.

Item 10. The method according to any of the previous items, wherein the control signalling comprises a flag indicating the fundamental set of the modulo operation.

Item 11. The method according to any of the previous items, wherein the fundamental set is indicative of a range determined based on a margin parameter. Item 12. The method according to any of the previous items, the method comprising receiving (S101 ), from the receiver device, control signalling indicative of a capability of the receiver device to apply the modulo operation to the version of the signal.

Item 13. A method, performed by a receiver device, for receiving a signal which has been modified for peak-to-average-power-ratio, PAPR, mitigation at a transmitter device, the method comprising: receiving (S202), from the transmitter device, control signalling indicative of a fundamental set of a modulo operation for enabling the receiver device to determine the signal from a version of the signal modified for PAPR mitigation; receiving (S204), from the transmitter device, the version of the signal modified for PAPR mitigation; and determining (S206) the signal by applying (S206A) the modulo operation to the version of the signal using the fundamental set.

Item 14. The method according to item 13, the method comprising: applying (S205) an equalization technique to the version of the signal for provision of an equalized signal.

Item 15. The method according to any of items 13-14, wherein applying (S206A) the modulo operation to the version of the signal comprises applying (S206AA) the modulo operation to the equalized signal using the fundamental set.

Item 16. The method according to any of items 13-15, wherein applying (S206A) the modulo operation to the version of the signal comprises removing (S206AB) a set of PAPR mitigation parameters from the version of the signal.

Item 17. The method according to any of items 13-16, wherein communicating (S202), between the receiver and the transmitter device, the control signalling comprises receiving (S202A), from the transmitter device, the control signalling.

Item 18. The method according to any of items 13-17, wherein communicating (S202), between the transmitter device and the receiver device, the control signalling comprises transmitting (S202B), to the transmitter device, the control signalling. Item 19. The method according to any of items 13-18, wherein the control signalling comprises information indicative of the fundamental set of the modulo operation.

Item 20. The method according to any of items 13-19, wherein the control signalling comprises capability signalling indicative of a capability of the transmitter device to apply the set of PAPR mitigation parameters.

Item 21. The method according to any of items 13-20, wherein the control signalling comprises an activation indication to activate the PAPR mitigation using the set of PAPR mitigation parameters.

Item 22. The method according to any of items 13-21 , wherein the control signalling comprises a flag indicating the fundamental set of the modulo operation.

Item 23. The method according to any of items 13-22, the method comprising transmitting (S201 ), to the transmitter device, control signalling indicative of a capability of the receiver device to apply the modulo operation to the version of the signal.

Item 24. A transmitter device comprising memory circuitry, processor circuitry, and a wireless interface, wherein the transmitter device is configured to perform any of the methods according to any of items 1-12.

Item 25. A receiver device comprising memory circuitry, processor circuitry, and a wireless interface, wherein the receiver device is configured to perform any of the methods according to any of items 13-23.

The use of the terms “first”, “second”, “third” and “fourth”, “primary”, “secondary”, “tertiary” etc. does not imply any particular order, but are included to identify individual elements. Moreover, the use of the terms “first”, “second”, “third” and “fourth”, “primary”, “secondary”, “tertiary” etc. does not denote any order or importance, but rather the terms “first”, “second”, “third” and “fourth”, “primary”, “secondary”, “tertiary” etc. are used to distinguish one element from another. Note that the words “first”, “second”, “third” and “fourth”, “primary”, “secondary”, “tertiary” etc. are used here and elsewhere for labelling purposes only and are not intended to denote any specific spatial or temporal ordering. Furthermore, the labelling of a first element does not imply the presence of a second element and vice versa. It may be appreciated that Figures comprise some circuitries or operations which are illustrated with a solid line and some circuitries, components, features, or operations which are illustrated with a dashed line. Circuitries or operations which are comprised in a solid line are circuitries, components, features, or operations which are comprised in the broadest example. Circuitries, components, features, or operations which are comprised in a dashed line are examples which may be comprised in, or a part of, or are further circuitries, components, features, or operations which may be taken in addition to circuitries, components, features, or operations of the solid line examples. It should be appreciated that these operations need not be performed in order presented. Furthermore, it should be appreciated that not all of the operations need to be performed. The example operations may be performed in any order and in any combination. It should be appreciated that these operations need not be performed in order presented. Circuitries, components, features, or operations which are comprised in a dashed line may be considered optional.

Other operations that are not described herein can be incorporated in the example operations. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations.

Certain features discussed above as separate implementations can also be implemented in combination as a single implementation. Conversely, features described as a single implementation can also be implemented in multiple implementations separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as any sub-combination or variation of any sub-combination.

It is to be noted that the word "comprising" does not necessarily exclude the presence of other elements or steps than those listed.

It is to be noted that the words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements.

It should further be noted that any reference signs do not limit the scope of the claims, that the examples may be implemented at least in part by means of both hardware and software, and that several "means", "units" or "devices" may be represented by the same item of hardware.

Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than or equal to 10% of, within less than or equal to 5% of, within less than or equal to 1% of, within less than or equal to 0.1 % of, and within less than or equal to 0.01% of the stated amount. If the stated amount is 0 (e.g., none, having no), the above recited ranges can be specific ranges, and not within a particular % of the value.

The various example methods, devices, nodes, and systems described herein are described in the general context of method steps or processes, which may be implemented in one aspect by a computer program product, embodied in a computer-readable medium, including computerexecutable instructions, such as program code, executed by computers in networked environments. A computer-readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory, ROM, Random Access Memory, RAM, compact discs, CDs, digital versatile discs, DVDs, etc. Generally, program circuitries may include routines, programs, objects, components, data structures, etc. that perform specified tasks or implement specific abstract data types. Computer-executable instructions, associated data structures, and program circuitries represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.

Although features have been shown and described, it will be understood that they are not intended to limit the claimed disclosure, and it will be made obvious to those skilled in the art that various changes and modifications may be made without departing from the scope of the claimed disclosure. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense. The claimed disclosure is intended to cover all alternatives, modifications, and equivalents.

Claims

1 . A method, performed by a transmitter device, for mitigating peak-to-average-power-ratio, PAPR, in a signal, the method comprising:

- communicating (S102), between the transmitter device and a receiver device, control signalling indicative of a fundamental set of a modulo operation for enabling the receiver device to determine the signal from a version of the signal modified for PAPR mitigation;

- determining (S104), based on the signal and the fundamental set, a set of PAPR mitigation parameters by solving (S104A) an optimization problem;

- generating (S106) the version of the signal based on the signal and the set of PAPR mitigation parameters; and

- transmitting (S108) the generated version of the signal to the receiver device.

2. The method according to claim 1 , wherein solving (S104A) the optimization problem comprises minimizing (S104AA) one or more maximum peaks of the signal.

3. The method according to any of the previous claims, wherein determining (S104) the set of PAPR mitigation parameters comprises: determining (S104B) one or more peaks of the signal; setting (S104C) each peak to a zero value for provision of a first signal; determining (S104D), based on the first signal, a second signal, wherein the second signal is a transformed representation of the first signal; and determining (S104E), based on the signal and the second signal, the set of PAPR mitigation parameters.

4. The method according to claim 3, wherein determining (S104) the set of PAPR mitigation parameters comprises approximating (S104F), based on the fundamental set, one or more elements of the set of PAPR mitigation parameters.

5. The method according to any of the previous claims, wherein communicating (S102), between the transmitter device and the receiver device, the control signalling comprises transmitting (S102A), to the receiver device, the control signalling.

6. The method according to any of the previous claims, wherein communicating (S102), between the transmitter device and the receiver device, the control signalling comprises receiving (S102B), from the receiver device, the control signalling.

7. The method according to any of the previous claims, wherein the control signalling comprises information indicative of the fundamental set of the modulo operation.

8. The method according to any of the previous claims, wherein the control signalling comprises capability signalling indicative of a capability of the transmitter device to modify the signal for PAPR mitigation.

9. The method according to any of the previous claims, wherein the control signalling comprises an activation indication to activate the PAPR mitigation using the set of PAPR mitigation parameters.

10. The method according to any of the previous claims, wherein the control signalling comprises a flag indicating the fundamental set of the modulo operation.

11. The method according to any of the previous claims, wherein the fundamental set is indicative of a range determined based on a margin parameter.

12. The method according to any of the previous claims, the method comprising receiving (S101 ), from the receiver device, control signalling indicative of a capability of the receiver device to apply the modulo operation to the version of the signal.

13. A method, performed by a receiver device, for receiving a signal which has been modified for peak-to-average-power-ratio, PAPR, mitigation at a transmitter device, the method comprising: communicating (S202), between the receiver device and the transmitter device, control signalling indicative of a fundamental set of a modulo operation for enabling the receiver device to determine the signal from a version of the signal modified for PAPR mitigation; receiving (S204), from the transmitter device, the version of the signal modified for PAPR mitigation; and determining (S206) the signal by applying (S206A) the modulo operation to the version of the signal using the fundamental set.

14. .The method according to claim 13, the method comprising: applying (S205) an equalization technique to the version of the signal for provision of an equalized signal.

15. The method according to any of claims 13-14, wherein applying (S206A) the modulo operation to the version of the signal comprises applying (S206AA) the modulo operation to the equalized signal using the fundamental set.

16. The method according to any of claims 13-14, wherein applying (S206A) the modulo operation to the version of the signal comprises removing (S206AB) a set of PAPR mitigation parameters from the version of the signal.

17. The method according to any of claims 13-16, wherein communicating (S202), between the receiver and the transmitter device, the control signalling comprises receiving (S202A), from the transmitter device, the control signalling.

18. The method according to any of claims 13-17, wherein communicating (S202), between the transmitter device and the receiver device, the control signalling comprises transmitting (S202B), to the transmitter device, the control signalling.

19. The method according to any of claims 13-18, wherein the control signalling comprises information indicative of the fundamental set of the modulo operation.

20. The method according to any of claims 13-19, wherein the control signalling comprises capability signalling indicative of a capability of the transmitter device to apply the set of PAPR mitigation parameters.

21. The method according to any of claims 13-20, wherein the control signalling comprises an activation indication to activate the PAPR mitigation using the set of PAPR mitigation parameters.

22. The method according to any of claims 13-21 , wherein the control signalling comprises a flag indicating the fundamental set of the modulo operation.

23. The method according to any of claims 13-22, the method comprising transmitting (S201 ), to the transmitter device, control signalling indicative of a capability of the receiver device to apply the modulo operation to the version of the signal.

24. A transmitter device comprising memory circuitry, processor circuitry, and a wireless interface, wherein the transmitter device is configured to perform any of the methods according to any of claims 1-12.

25. A receiver device comprising memory circuitry, processor circuitry, and a wireless interface, wherein the receiver device is configured to perform any of the methods according to any of claims 13-23.