WO2025214580A1

WO2025214580A1 - Truncated filterbank implementation of an fft-less dft-s-ofdm in a communication network

Info

Publication number: WO2025214580A1
Application number: PCT/EP2024/059548
Authority: WO
Inventors: Muris Sarajlic; Robert Baldemair; Medhat MOHAMAD; Shousheng He; Dennis Hui
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2024-04-09
Filing date: 2024-04-09
Publication date: 2025-10-16
Anticipated expiration: 2026-10-09

Abstract

A method is provided that is performed by a device comprising a digital baseband of a communication transmitter. The method includes setting (1102) a first portion of a plurality of elements in a time variant filter to zero to obtain a truncated time variant filter; and generating (1104) an approximate discrete Fourier transform spread-orthogonal frequency division multiplexing, DFTS-OFDM, waveform based on filtering data symbols in time domain with the truncated time variant filter.

Description

TRUNCATED FILTERBANK IMPLEMENTATION OF AN FFT-LESS DFT-S-OFDM IN A COMMUNICATION NETWORK

TECHNICAL FIELD

The present disclosure relates generally to methods performed by a device including a baseband of a communication transmitter for fast Fourier transform (FFT)-less discrete Fourier transform spread-orthogonal frequency division multiplexing (DFTS-OFDM), and related methods and devices.

BACKGROUND

A DFTS-OFDM waveform may be is obtained by inserting a size-M DFT after a symbol generation block in a conventional OFDM baseband transmitter 100 as shown in the example in Figure 1. A resulting time-domain waveform may have a lower envelope variation than an ordinary OFDM waveform. Thus, DFTS-OFDM may be beneficial for use in cases where power amplifier operation is limited either by efficiency or by a cap on output power, since DFTS- OFDM may enable higher average transmit power without any other structural changes to radio frequency (RF) transmitter hardware. This may be a reason why DFTS-OFDM has been adopted for fourth generation (4G) and fifth generation (5G) uplink, and also is also being considered for adoption in the downlink of sixth generation (6G) to operate at frequencies 100 - 300 GHz (sub- THz), for example. In 4G and 5G parlance, DFTS-OFDM also may be referred to as single-carrier frequency domain multiple access (SC-FDMA) or as transform-precoded OFDM, for example.

DFT-precoded symbols may be mapped to subcarriers in two ways: localized/block- mapping (where all precoded symbols occupy a contiguous block of subcarriers) and interleaved mapping (where precoded symbols occupy every Kth subcarrier). In 4G and 5G, block mapping is used. DFTS-OFDM with block mapping is equivalent to time-domain circular convolution of original complex symbols (e.g., from a QAM constellation) and a discrete-time sync impulse response.

Figure 2 is a drawing illustrating an example of a functional diagram of DFTS-OFDM. Envelope variations in DFTS-OFDM may be further reduced by periodically repeating the subcarriers in frequency domain for a block subcarrier allocation and applying a frequency domain filter afterwards, as shown in the example in Figure 3.

Figure 3 is a drawing illustrating an example of DFTS-OFDM with frequency-domain filtering. A DFTS-OFDM transmitter can be modeled as a time-domain resampling filter. Considering the diagram in Figure 3, for example, the relation between the length-M vector x of modulation symbols and length-N vector y of time domain samples at the output of the IDFT before the cyclic prefix can be expressed as: where F^¹ is a IV X IV matrix representing a length-N IDFT, P is a N X M matrix representing the linear operations of subcarrier mapping, subcarrier repetition and frequency domain filtering, and F_M is a M X M matrix implementing a length-M DFT. The N X M matrix A is simply A = F^PFM, and it represents a resampling/interpolation filter.

SUMMARY

Some approaches for generating a DFTS-OFDM waveform use an FFT or inverse FFT (IFFT), which may be power consuming, especially when bandwidth is large for example. This may be a particular challenge in battery driven devices such as user equipment (UEs).

For example, some approaches may represent DFTS-OFDM via an equivalent timedomain filter where the peak-to-average power ratio (PAPR) impact of the filter coefficients are also evaluated. However, in such approaches, the time domain representation may be used for the purpose of theoretical analysis of the precoder and not to implement a DFTS-OFDM transmitter. Moreover, practical cases where M,N values close to each other may not be included in such approaches.

Other approaches may include DFTS-OFDM transmitters implemented using FFT and inverse FFT (IFFT) for the DFT and inverse DFT (IDFT) functions, respectively. Although FFT may have a lower complexity than a straightforward implementation of DFT, FFT may not always have low power. For example, at high throughputs/ sampling rates, FFT can be power hungry and dominate the digital baseband power consumption, for example. As such, this may be a limitation for the implementation of battery-powered mobile devices intended to support high throughputs, e.g., mobile devices operating at mmWave frequencies (e.g., where abundant bandwidth can support high throughputs).

Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges.

Some embodiments provide a method performed by a device including a digital baseband of a communication transmitter. The method includes setting a first portion of a plurality of elements in a time variant filter to zero to obtain a truncated time variant filter; and generating an approximate DFTS-OFDM waveform based on filtering data symbols in time domain with the truncated time variant filter. Other embodiments provide a device including a digital baseband of a communication transmitter; processing circuitry; and memory coupled with the processing circuitry. The memory includes instructions that when executed by the processing circuitry causes the device to perform operations. The operations includes to set a first portion of a plurality of elements in a time variant filter to zero to obtain a truncated time variant filter; and to generate an approximate DFTS-OFDM waveform based on filtering data symbols in time domain with the truncated time variant filter.

Still other embodiments provide a non-transitory computer readable medium including program code to be executed by processing circuitry of a device. Execution of the program code causes the program code to perform operations. The operations includes to set a first portion of a plurality of elements in a time variant filter to zero to obtain a truncated time variant filter; and to generate an approximate DFTS-OFDM waveform based on filtering data symbols in time domain with the truncated time variant filter.

Certain embodiments may provide one or more of the following technical advantage(s). Based on use of a truncated time variant filter A to generate DFTS-OFDM directly in time domain (e.g., without using DFT and IDFT implemented by FFTs) may result in a decrease (e.g., significant decrease) of complexity and power consumption compared to FFT-based DFTS- OFDM synthesis, for example. Such a decrease, in turn, may lead to better battery life for devices implementing such DFTS-OFDM synthesis. An additional technical advantage may include that properties of filter A may lend themselves to a convenient polyphase filter bank implementation.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate certain non-limiting embodiments of the present disclosure. In the drawings:

Figure l is a drawing illustrating an example of a functional diagram of OFDM;

Figure 2 is a drawing illustrating an example of a functional diagram of DFTS-OFDM;

Figure 3 is a drawing illustrating an example of DFTS-OFDM with frequency-domain filtering;

Figure 4 is a high-level diagram of an example DFTS-OFDM transmitter baseband in accordance with some embodiments;

Figure 5 is a plot of an example comparison of true and approximate DFTS-OFDM in accordance with some embodiments;

Figure 6 is drawing showing an example excerpt from a sort-and-null process to form an approximate filter A in accordance with some embodiments; Figure 7 is a drawing showing an example excerpt from an equal band width nulling process to form an approximate filter A in accordance with some embodiments;

Figures 8A and 8B are plots of error vector magnitude (EVM) performance of an example process in accordance with some embodiments as a function of percentage of non-zero entries in A;

Figure 9 is a plot of an example of complexity savings in accordance with some embodiments;

Figure 10 is a plot of an example of maximum complexity savings as function of an EVM requirement in accordance with some embodiments;

Figure 11 is a flowchart illustrating operations of a device in accordance with some embodiments;

Figure 12 is a block diagram of a communication system in accordance with some embodiments;

Figure 13 is a block diagram of a user equipment (UE) in accordance with some embodiments;

Figure 14 is a block diagram of a network node (e.g., a device) in accordance with some embodiments; and

Figure 15 is a block diagram of a virtualization environment in accordance with some embodiments.

DETAILED DESCRIPTION

Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art, in which examples of embodiments of the present disclosure are shown. Inventive concepts may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. It should also be noted that these embodiments are not mutually exclusive. Components from one embodiment may be tacitly assumed to be present/used in another embodiment.

Some examples of the present disclosure include a time domain filter A implementing a DFTS-OFDM transmitter that is modified by nulling the filter taps with low energy, resulting in filter A which is used to generate an approximation of the DFTS-OFDM waveform directly in time domain, without using FFTs. That is, the DFTS-OFDM is generated in the time domain by using a filter matrix that is a truncated version of a time domain filter A. Some examples include applying such a process in scenarios with high bandwidths (e.g., 400 MHz - 2 GHz range) and at a UE.

The choice of how many taps of A are nulled may include a tradeoff of complexity for performance and can be adapted based on modulation, channel conditions, signal to noise ratio (SNR), etc.

Some examples herein include a process implemented in digital baseband of a communication transmitter to generate a DFTS-OFDM waveform directly in time domain using a resampling filter A (e.g., a NxM matrix). The process may include the following operations:

1. Setting the low energy taps of filter A (e.g., a time variant filter) in equation (1) to zero (resulting in truncated filter A)

2. Generating a DFTS-OFDM waveform by filtering data symbols directly in time domain using the truncated filter A obtained in operation 1 ;

3. Modifying the number of filter taps set to zero in operation 1 , dynamically or statically, based on scheduling, system and/or environment parameters. Parameters may include, without limitation, modulation (e.g., quadrature phase shift keying (QPSK) or 64-quadrature amplitude modulation (64-QAM), number of occupied subcarriers M, channel conditions (e.g., SNR), EVM requirements, properties of a frequency domain shaping filter (e.g., such as in Figure 3), etc.

Thus, in some embodiments, a method is performed by a device including a digital baseband of a communication transmitter. The method includes setting (operation 1102 in Figure 11) a first portion of a plurality of elements in a time variant filter to zero to obtain a truncated time variant filter. The method further includes generating (operation 1104 in Figure 11) an approximate discrete Fourier transform spread-orthogonal frequency division multiplexing, DFTS-OFDM, waveform based on filtering data symbols in time domain with the truncated time variant filter.

The device can be a user equipment (UE) or a network node (e.g., a base station), as discussed further herein.

Formulating A may include a two-step process. In the first step, matrix A is formulated that embodies the functionality of DFT, IDFT and subcarrier mapping and frequency domain filtering. For example, IFFT can be a concatenation of three linear transformations representing DFT, subcarrier mapping and frequency domain filtering and IDFT, respectively, which can be represented as one linear transformation (e.g., matrix multiplication) with matrix A. In a second step, matrix A has elements with amplitudes having high values on or about a diagonal (referred to herein as diagonally dominant). Elements outside such a diagonal, having lower values, are put to zero. The resulting matrix is A. In some embodiments, the time variant filter includes a first matrix of elements that includes the first portion of the plurality of elements having non-zero values and the truncated time variant filter includes a second diagonal dominant matrix of elements with the first portion of the plurality of elements having zero values.

A DFTS-OFDM waveform is then generated by filtering with A instead of A.

When a sufficient number of entries of A are put to zero, computational complexity may be reduced compared to other approaches of generating DFTS-OFDM. There may be some distortion introduced in the waveform as A is an approximation of A. As discussed further herein, a simulation shows that for acceptable levels of distortion, complexity reduction was 45 - 70%.

Discussion of the process of examples herein starts by analyzing the structure of a time domain filter A = F^PFM (e.g., of Figure 3). Matrix A includes respective amplitude values for respective matrix entries at respective positions (n, m). In other words, the matrix A includes the amplitude of respective elements a_{n m}.

Matrix A may be banded, for example with only a few essentially non-zero entries around a main diagonal. This means that elements close to zero can be set to zero, resulting in an approximation A of matrix A. As shown in Figure 4, if QAM symbol vector x is multiplied by A in a transmitter baseband 100, the resulting waveform y = Ax is an approximation of the DFTS- OFDM symbol y. Figure 5 is a plot of an example showing a real part of true DFTS-OFDM time domain waveform y shown by the solid line compared with a real part of the corresponding approximate waveform y shown by the dashed line for the vector x of QAM symbols.

Matrix-vector multiplication Ax , operations (e.g., multiplications and additions) related to nulled-out entries in A can be skipped. As a consequence, the computational complexity of matrix-vector multiplication Ax is lower than the complexity of performing the multiplication Ax. Moreover, the complexity of matrix-vector multiplication Ax may also be lower than the complexity of performing FFT, IFFT and frequency domain filtering. The number of nulled-out entries in A is in direct proportion to the distortion introduced by approximating y with y. In other words, the number of nulled-out entries A (or equivalently, the number of non-zero entries in A) trades off complexity with distortion.

Additionally, examples herein can include different ways (referred to herein as different truncation or nulling processes) of truncating matrix A. A truncation process may be chosen for truncating matrix A to fit different performance or complexity constraints, for example. In some embodiments, determining (operation 1100 in Figure 11) a quantity of the first portion of the plurality of elements in the time variant filter to set to zero based on at least one of (i) a sort and null process, and (ii) an equal bandwidth nulling process.

A first sort and null process can include: sorting the plurality of elements in the time variant filter by a amplitude value; retaining a second portion of the elements in the time variant filter that respectively have an amplitude that is greater than or equal to a positive threshold amplitude value; setting the first portion of the plurality elements in the time variant filter to zero; and forming the truncated time variant filter using the first portion and the second portion of the plurality of elements.

A second sort and null process can include a process where R (out of total of MN) elements of A with largest amplitude are retained and the rest are set to zero. This second sort and null process can include the following steps: (1) Sort elements in A by amplitude: |; (2) Retain top R elements in the list sorted by amplitude in step 1, set remaining MN — R elements to zero; and (3) Form approximation A « A using the retained elements.

Thus, in some embodiments, determining (operation 1100 in Figure 11) a quantity of the first portion of the plurality of elements in the time variant filter to set to zero based on a sort and null process includes the following: sorting the plurality of elements in the time variant filter by amplitude value; retaining a second portion of the elements in the time variant filter wherein the number of elements in the second portion of the elements is a fraction R of the total number of elements in the second matrix; setting the first portion of the plurality elements in the time variant filter to zero; and forming the truncated time variant filter using the first portion and second portion of the plurality of elements.

The positive threshold amplitude value and fraction R, in some embodiments, are based on a target level of performance decided by a communication system.

In some embodiments, at least one of the positive threshold amplitude value or an identity of the second portion of the elements or fraction R is received from a node in a communication system.

Figure 6 is a drawing of an example of an excerpt 600 of an approximate filter A obtained from a sort and null process. Figure 6 includes excerpt 600 of corresponding sections of A and A obtained by sort-and-null from A. As shown in this example, the sort-and-null process sets to zero those elements of A that have low energy and, thus, contribute little to the overall filtering result.

It is noted that the number of non-zero elements may vary between the rows of A obtained by sort and null process, as illustrated in the example in Figure 6. In a practical implementation, matrix-vector multiplication Ax may be implemented by a polyphase filter bank, where each row of A would represent coefficients of a finite impulse response (FIR) filter in the filter bank. In such an implementation, it may be beneficial from implementation complexity point of view to have the same FIR filter length for all filters in the bank. Thus, the number of non-zero elements may be the same for each row of A . This may be achieved by a second truncation process referred to herein as “equal band width nulling”.

An equal band width nulling process may include the following steps:

1. For each row i of A a) determine center-of-mass tap j_peak,' b) retain r taps a _j- symmetrically placed around j_peak and null the rest

• where symmetrically placed is taken in modulo-M sense, that is indices can wrap around (e.g., if j_peak ⁼ 2 and r = 5 and M = 2048, retained indices are 1, 2, 3, 4 and 2048);

2. Form approximation A « A using the retained elements.

Thus, in some embodiments, determining (operation 1100 in Figure 11) a quantity of the first portion of the plurality of elements in the time variant filter to set to zero based on an equal band width nulling process includes, for a respective row of elements in the time variant filter: determining an element or elements having a peak magnitude in the respective row; retaining a sub-set of elements having a non-zero value in the respective row that are symmetrically placed around the element or elements having the peak magnitude; and setting a remainder of the sub-set of elements in the respective row to zero.

Figure 7 is a drawing of an example of an excerpt 700 of an approximate filter A obtained from an equal band width nulling process. In particular, the example in Figure 7 shows excerpt 700 of corresponding sections of A and A obtained by equal band width nulling, with r = 5. It is noted that for the first two rows of the matrix in Figure 7, the retained elements are at the end of the row due to modulo-M symmetrical banding.

As discussed herein, the number of retained (non-zero) entries in A can be used to tradeoff complexity with distortion arising from approximating the DFTS-OFDM waveform. The total number of non-zero entries of A can be denoted with R, then the percentage of retained (non- zero) entries in A is p = — . In some example, the dependence of distortion and complexity savings of the process on p can then be quantified. For example,

• For a measure of distortion, an EVM measure can be used on equalized and QAM symbols after the transmitter in a noise free case. • Complexity savings can be measured with respect to legacy (FFT-based) DFTS- OFDM synthesis.

More specifically, in this example, complexity of FFT-based synthesis can be calculated as:

CppT = fppr( T) + fppT^^’ where f_FFT X') is a complexity metric quantifying the number of operations needed for calculation of a X-sized FFT : f_FFT(X) = [X(log₂ X - 3) + 4] + 0.1[3X(log₂ X - 1) + 4 ],

In the above expression, the expressions in the first and second square brackets are the numbers of real multiplications and real additions, respectively. It is assumed that a multiplier will consume lOx more energy than an adder, thus the adder complexity is weighted by 0.1. The joint metric f_FFT(X can be considered to be a measure of energy consumption of the FFT.

For symmetric subcarrier allocations, it was found that matrix A is purely real, which requires two real multiplications per one multiplication of an entry in A and a complex QAM symbol. Consequently, and according to the complexity weighting described above, the complexity metric of in this example is: 0.1[A(2pM - 1)], fl _ _ where p r = — is the fraction of non-zero taps in A . MN

Figures 8A and 8B show, for this example, the EVM as a function of the percentage of non-zero taps p, for N = 4096 (size of IFFT) and various sizes M of the FFT. The dashed lines indicate EVM requirements from the new radio (NR) specification for particular constellations, halved because, e.g., halved may ensure that a non-complete EVM budget is consumed by this approximation process. It is noted that increasing the rolloff of the frequency-domain shaping root- raised-cosine (RRC) filter may help bring the EVM down.

Figure 9 is a plot of an example of complexity savings (compared to FFT-based implementation) as a function of the EVM requirement. In this example, the complexity savings function of p are shown.

Figure 10 is a plot of an example of maximum complexity savings as a function of the EVM requirement. In this example, the maximum possible complexity reduction, found for minimum % of non-zero taps satisfying the EVM constraint, under the EVM constraints shown in Figure 8. The result in Figure 10 indicates the potential of the example process to significantly reduce the complexity of transmitter baseband. As shown by the example results in Figure 8, the amount of filter truncation (represented by the converse metric p) may depend on the EVM requirement and the number of allocated subcarriers M. In some examples, the transmitter dynamically adapts the number of nonzero entries of A and, thus, the amount of truncation according to environment conditions or scheduling decisions. The percentage of non-zero entries p can be adapted, without limitation, to (a) a number of occupied subcarriers M (e.g., when switching from M = 3072 to M = 2048). That is, the required number of retained taps depends on allocation; (b) modulation used (e.g., when switching from QPSK to 16-QAM); (c) SNR or signal to interference noise ratio (SINR), (d) properties of frequency domain shaping filter (e.g., if the FD shaping filter is RRC, switching the rolloff factor from 0 to 0.25), and/or (e) symmetric versus asymmetric allocation, which lead to real versus, complex matrix A , can impact complexity.

Filtering data symbols in time domain with the truncated time variant filter can include multiplying a vector of symbols from a digital modulation by the truncated time variant filter.

In some embodiments, the method further includes dynamically modifying (operation 1106 in Figure 11) a quantity of elements in the first portion of the plurality of elements that are set to zero. Modifying (operation 1106) can be based on a parameter. The parameter can include at least one of (i) a modulation parameter, (ii) a number of digital modulation symbols in a DFTS- OFDM symbol, (iii) a channel condition, (iv) an EVM criterion, and (v) a property of a frequency domain shaping filter.

In some embodiments, modifying (operation 1106) a quantity of elements in the first portion of the plurality of elements that are set to zero is based on at least one of an environmental condition and a scheduling decision.

In other embodiments, modifying (operation 1106) a quantity of elements in the first portion of the plurality of elements that are set to zero is adapted based on at least one of the following: a number of digital modulation symbols in a DFTS-OFDM symbol; a modulation used; a signal to noise (SNR) ratio; a signal to interference and noise (SINR) ratio; a property of a frequency domain shaping filter; a symmetrical allocation of the bandwidth allocated for the data transmission within the configured channel; and an asymmetrical allocation of the bandwidth allocated for the data transmission within the configured channel.

In yet other embodiments, modifying (operation 1106) a quantity of elements in the first portion of the plurality of elements that are set to zero is modified based on switching from a quadrature phase shift keying (QPSK) modulation to a QAM with a number of bits per symbol higher than 2. Operations of a device can be performed by the UE 1300 of Figure 13 or the network node 1400 of Figure 14. Operations of the device (implemented using the structure of Figure 13 or Figure 14) have been discussed with reference to the flow chart of Figure 11 according to some embodiments of the present disclosure. Operations 1100 and 1105 from the flow chart of Figure 11 may be optional with respect to some embodiments of devices and related methods. Modules may be stored in memory 1310 of Figure 13 or 1404 of Figure 14, for example, and these modules may provide instructions so that when the instructions of a module are executed by respective device processor 1302 in Figure 13 or 1402 in Figure 14 (also referred to herein as processing circuitry), device 1300, 1400 performs respective operations of the flow chart of Figure 11.

Figure 12 shows an example of a communication system 1200 in accordance with some embodiments.

In the example, the communication system 1200 includes a telecommunication network 1202 that includes an access network 1204, such as a radio access network (RAN), and a core network 1206, which includes one or more core network nodes 1208. The access network 1204 includes one or more access network nodes, such as network nodes 1210a and 1210b (one or more of which may be generally referred to as network nodes 1210), or any other similar 3^rd Generation Partnership Project (3 GPP) access nodes or non-3GPP access points. Moreover, as will be appreciated by those of skill in the art, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunication network 1202 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network 1202 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication network 1202, including one or more network nodes 1210 and/or core network nodes 1208.

Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU- CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an 0-2 interface defined by the 0-RAN Alliance or comparable technologies. The network nodes 1210 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 1212a, 1212b, 1212c, and 1212d (one or more of which may be generally referred to as UEs 1212) to the core network 1206 over one or more wireless connections.

Example wireless communications over a wireless connection include transmitting and/or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and/or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 1200 may include any number of wired or wireless networks, network nodes, UEs, and/or any other components or systems that may facilitate or participate in the communication of data and/or signals whether via wired or wireless connections. The communication system 1200 may include and/or interface with any type of communication, telecommunication, data, cellular, radio network, and/or other similar type of system.

The UEs 1212 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and/or operable to communicate wirelessly with the network nodes 1210 and other communication devices. Similarly, the network nodes 1210 are arranged, capable, configured, and/or operable to communicate directly or indirectly with the UEs 1212 and/or with other network nodes or equipment in the telecommunication network 1202 to enable and/or provide network access, such as wireless network access, and/or to perform other functions, such as administration in the telecommunication network 1202.

In the depicted example, the core network 1206 connects the network nodes 1210 to one or more hosts, such as host 1216. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 1206 includes one more core network nodes (e.g., core network node 1208) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and/or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 1208. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and/or a User Plane Function (UPF).

The host 1216 may be under the ownership or control of a service provider other than an operator or provider of the access network 1204 and/or the telecommunication network 1202, and may be operated by the service provider or on behalf of the service provider. The host 1216 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio/video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

As a whole, the communication system 1200 of Figure 12 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and/or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and/or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and/or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.

In some examples, the telecommunication network 1202 is a cellular network that implements 3GPP standardized features. Accordingly, the telecommunications network 1202 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 1202. For example, the telecommunications network 1202 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and/or Massive Machine Type Communication (mMTC)ZMassive loT services to yet further UEs.

In some examples, the UEs 1212 are configured to transmit and/or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 1204 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 1204. Additionally, a UE may be configured for operating in single- or multi-RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e., being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC).

In the example, the hub 1214 communicates with the access network 1204 to facilitate indirect communication between one or more UEs (e.g., UE 1212c and/or 1212d) and network nodes (e.g., network node 1210b). In some examples, the hub 1214 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 1214 may be a broadband router enabling access to the core network 1206 for the UEs. As another example, the hub 1214 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 1210, or by executable code, script, process, or other instructions in the hub 1214. As another example, the hub 1214 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 1214 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub 1214 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 1214 then provides to the UE either directly, after performing local processing, and/or after adding additional local content. In still another example, the hub 1214 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

The hub 1214 may have a constant/persistent or intermittent connection to the network node 1210b. The hub 1214 may also allow for a different communication scheme and/or schedule between the hub 1214 and UEs (e.g., UE 1212c and/or 1212d), and between the hub 1214 and the core network 1206. In other examples, the hub 1214 is connected to the core network 1206 and/or one or more UEs via a wired connection. Moreover, the hub 1214 may be configured to connect to an M2M service provider over the access network 1204 and/or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 1210 while still connected via the hub 1214 via a wired or wireless connection. In some embodiments, the hub 1214 may be a dedicated hub - that is, a hub whose primary function is to route communications to/from the UEs from/to the network node 1210b. In other embodiments, the hub 1214 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 1210b, but which is additionally capable of operating as a communication start and/or end point for certain data channels.

As shown in Figures 13 and 14, the device 1300, 1400 includes processor 1302, 1402 that is operatively coupled to memory 1310, 1404, communication interface 1312, 1406, and/or any other component, or any combination thereof. Certain devices may utilize all or a subset of the components shown in Figures 13, 14. The level of integration between the components may vary from one device to another device. Further, certain devices may contain multiple instances of a component, such as multiple processors, memories, etc.

The processor 1302, 1402 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory 1310, 1404. The processor 1302, 1402 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processor 1302, 1402 may include multiple central processing units (CPUs).

In the example, the communication interface 1312, 1406 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and/or output devices. Examples of an output device include a display, a monitor, a printer, another output device, or any combination thereof. An input device may allow a user to capture information into the device 1300, 1400. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, a force sensor, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

The memory 1310, 1404 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable readonly memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 1310, 1404 includes one or more application programs, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data. The memory 1310, 1404 may store, for use by the device 1300, 1400, any of a variety of various operating systems or combinations of operating systems.

The memory 1310, 1404 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD- DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and/or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory 1310, 1404 may allow the device 1300, 1400 to access instructions, application programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory 1310, 1404 which may be or comprise a device-readable storage medium.

The processor 1302, 14023 may be configured to communicate with a network using the communication interface 1312, 1406. The communication interface 1312, 1406 may comprise one or more communication subsystems. The communication interface 1312, 1406 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another device, local computing device, edge node, cloud node, etc.). Each transceiver may include a transmitter and/or a receiver appropriate to provide network communications (e.g., optical, electrical, and so forth).

In the illustrated embodiment, communication functions of the communication interface 1312, 1406 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short- range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented according to one or more communication protocols and/or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), global system for mobile communications (GSM), long term evolution (LTE), New Radio (NR), Universal Mobile Telecommunications System (UMTS), WiMax, Ethernet, transmission control protocol/internet protocol (TCP/IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

Figure 15 is a block diagram illustrating a virtualization environment 1500 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments 1500 hosted by one or more of hardware nodes, such as a hardware device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment 1500 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an O-2 interface.

Applications 1502 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and/or benefits of some of the embodiments disclosed herein.

Hardware 1504 includes processing circuitry, memory that stores software and/or instructions executable by hardware processing circuitry, and/or other hardware devices as described herein, such as a network interface, input/output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 1506 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1508a and 1508b (one or more of which may be generally referred to as VMs 1508), and/or perform any of the functions, features and/or benefits described in relation with some embodiments described herein. The virtualization layer 1506 may present a virtual operating platform that appears like networking hardware to the VMs 1508.

The VMs 1508 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 1506. Different embodiments of the instance of a virtual appliance 1502 may be implemented on one or more of VMs 1508, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

In the context of NFV, a VM 1508 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 1508, and that part of hardware 1504 that executes that VM, be it hardware dedicated to that VM and/or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 1508 on top of the hardware 1504 and corresponds to the application 1502.

Hardware 1504 may be implemented in a standalone network node with generic or specific components. Hardware 1504 may implement some functions via virtualization. Alternatively, hardware 1504 may be part of a larger cluster of hardware (e.g., such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 1510, which, among others, oversees lifecycle management of applications 1502. In some embodiments, hardware 1504 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 1512 which may alternatively be used for communication between hardware nodes and radio units.

Although the device described herein may include the illustrated combination of hardware components, other embodiments may comprise devices with different combinations of components. It is to be understood that these devices may comprise any suitable combination of hardware and/or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the device, and/or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and/or the functionality of the components may be partitioned between the processor and the network interface. In another example, non- computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.

In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer- readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the device, but are enjoyed by the device as a whole, and/or by end users and a wireless network generally.

In certain embodiments, a device (1210, 1212, 1300, 1400) is provided. The device includes processing circuitry (1302, 1402); and memory (1310, 1404) connected to the processing circuitry (1302, 1402) and storing program code that is executed by the processing circuitry to perform operations. The operations include to perform some or all of the functionality described herein.

In certain embodiments, a non-transitory computer readable medium (1310, 1404) including program code to be executed by processing circuitry (100, 1302, 1402) of a device (1210, 1212, 1300, 1400) is provided. Execution of the program code causes the device to perform operations. The operations include to perform some or all of the functionality described herein.

Further definitions and embodiments are discussed below.

In the above-description of certain embodiments of the present disclosure, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which concepts of the present disclosure belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

When an element is referred to as being “connected”, “coupled”, “responsive”, or variants thereof to another element, it can be directly connected, coupled, or responsive to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected”, “directly coupled”, “directly responsive”, or variants thereof to another element, there are no intervening elements present. Like numbers refer to like elements throughout. Furthermore, “coupled”, “connected”, “responsive”, or variants thereof as used herein may include wirelessly coupled, connected, or responsive. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Well-known functions or constructions may not be described in detail for brevity and/or clarity. The term “and/or” (abbreviated “/”) includes any and all combinations of one or more of the associated listed items.

It will be understood that although the terms first, second, third, etc. may be used herein to describe various elements/operations, these elements/operations should not be limited by these terms. These terms are only used to distinguish one element/operation from another element/operation. Thus a first element/operation in some embodiments could be termed a second element/operation in other embodiments without departing from the teachings of concepts of the present disclosure. The same reference numerals or the same reference designators denote the same or similar elements throughout the specification.

As used herein, the terms “comprise”, “comprising”, “comprises”, “include”, “including”, “includes”, “have”, “has”, “having”, or variants thereof are open-ended, and include one or more stated features, integers, elements, steps, components, or functions but does not preclude the presence or addition of one or more other features, integers, elements, steps, components, functions, or groups thereof. Furthermore, as used herein, the common abbreviation “e.g ”, which derives from the Latin phrase “exempli gratia,” may be used to introduce or specify a general example or examples of a previously mentioned item, and is not intended to be limiting of such item. The common abbreviation “i.e ”, which derives from the Latin phrase “id est,” may be used to specify a particular item from a more general recitation.

Example embodiments are described herein with reference to block diagrams and/or flowchart illustrations of computer-implemented methods, apparatus (systems and/or devices) and/or computer program products. It is understood that a block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by computer program instructions that are performed by one or more computer circuits. These computer program instructions may be provided to a processor circuit of a general purpose computer circuit, special purpose computer circuit, and/or other programmable data processing circuit to produce a machine, such that the instructions, which execute via the processor of the computer and/or other programmable data processing apparatus, transform and control transistors, values stored in memory locations, and other hardware components within such circuitry to implement the functions/acts specified in the block diagrams and/or flowchart block or blocks, and thereby create means (functionality) and/or structure for implementing the functions/acts specified in the block diagrams and/or flowchart block(s).

These computer program instructions may also be stored in a tangible computer- readable medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instructions which implement the functions/acts specified in the block diagrams and/or flowchart block or blocks. Accordingly, embodiments of the present disclosure may be embodied in hardware and/or in software (including firmware, resident software, micro-code, etc.) that runs on a processor such as a digital signal processor, which may collectively be referred to as “circuitry,” “a module” or variants thereof.

It should also be noted that in some alternate implementations, the functions/acts noted in the blocks may occur out of the order noted in the flowcharts. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Moreover, the functionality of a given block of the flowcharts and/or block diagrams may be separated into multiple blocks and/or the functionality of two or more blocks of the flowcharts and/or block diagrams may be at least partially integrated. Finally, other blocks may be added/inserted between the blocks that are illustrated, and/or blocks/operations may be omitted without departing from the scope of the present disclosure. Moreover, although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows.

Many variations and modifications can be made to the embodiments without substantially departing from the principles of the present disclosure. All such variations and modifications are intended to be included herein within the scope of present disclosure. Accordingly, the above disclosed subject matter is to be considered illustrative, and not restrictive, and the examples of embodiments are intended to cover all such modifications, enhancements, and other embodiments, which fall within the spirit and scope of the present disclosure. Thus, to the maximum extent allowed by law, the scope of the present disclosure is to be determined by the broadest permissible interpretation of the present disclosure including the examples of embodiments and their equivalents, and shall not be restricted or limited by the foregoing detailed description.

Claims

CLAIMS:

1. A method performed by a device comprising a digital baseband of a communication transmitter, the method comprising: setting (1102) a first portion of a plurality of elements in a time variant filter to zero to obtain a truncated time variant filter; and generating (1104) an approximate discrete Fourier transform spread-orthogonal frequency division multiplexing, DFTS-OFDM, waveform based on filtering data symbols in time domain with the truncated time variant filter.

2. The method of Claim 1, wherein the time variant filter comprises a first matrix of elements that includes the first portion of the plurality of elements having non-zero values and the truncated time variant filter comprises a second diagonal dominant matrix of elements with the first portion of the plurality of elements having zero values.

3. The method of any one of Claims 1 to 2, further comprising: determining (1100) a quantity of the first portion of the plurality of elements in the time variant filter to set to zero based on at least one of (i) a sort and null process, and (ii) an equal bandwidth nulling process.

4. The method of Claim 3, wherein the determining (1100) a quantity of the first portion of the plurality of elements in the time variant filter to set to zero based on a first sort and null process comprises: sorting the plurality of elements in the time variant filter by amplitude value, retaining a second portion of the elements in the time variant filter that respectively have an amplitude that is greater than or equal to a positive threshold amplitude value, setting the first portion of the plurality elements in the time variant filter to zero, and forming the truncated time variant filter using the first portion and the second portion of the plurality of elements.

5. The method of Claim 3, wherein the determining (1100) a quantity of the first portion of the plurality of elements in the time variant filter to set to zero based on a second sort and null process comprises: sorting the plurality of elements in the time variant filter by amplitude value, retaining a second portion of the elements in the time variant filter wherein the number of elements in the second portion of the elements is a fraction R of the total number of elements in the second matrix, setting the first portion of the plurality elements in the time variant filter to zero, and forming the truncated time variant filter using the first portion and the second portion of the plurality of elements.

6. The method of Claims 4 and 5, wherein the positive threshold amplitude value and fraction R are based on a target level of performance decided by a communication system.

7. The method of Claims 4 and 5, wherein at least one of the positive threshold amplitude value or an identity of the second portion of the elements or fraction R is received from a node in a communication system.

8. The method of Claim 3, wherein the determining (1100) a quantity of the first portion of the plurality of elements in the time variant filter to set to zero based on an equal bandwidth nulling process comprises, for a respective row of elements in the time variant filter: determining an element or elements having a peak magnitude in the respective row, retaining a sub-set of elements having a non-zero value in the respective row that are symmetrically placed around the element or elements having the peak magnitude, and setting a remainder of the sub-set of elements in the respective row to zero.

9. The method of any one of Claims 1 to 8, wherein the filtering data symbols in time domain with the truncated time variant filter comprises multiplying a vector of symbols from a digital modulation by the truncated time variant filter.

10. The method of any one of Claims 1 to 9, further comprising: dynamically modifying (1106) a quantity of elements in the first portion of the plurality of elements that are set to zero.

11. The method of Claim 10, wherein the modifying (1106) a quantity of elements in the first portion of the plurality of elements that are set to zero is based on a parameter.

12. The method of Claim 11, wherein the parameter comprises at least one of (i) a modulation parameter, (ii) a number of digital modulation symbols in a DFTS-OFDM symbol, (iii) a channel condition, (iv) an error vector magnitude, EVM, criterion, and (v) a property of a frequency domain shaping filter.

13. The method of any one of Claims 10 to 12, wherein the modifying (1106) a quantity of elements in the first portion of the plurality of elements that are set to zero is based on at least one of an environmental condition and a scheduling decision.

14. The method of any one of Claims 10 to 13, wherein the modifying (1106) a quantity of elements in the first portion of the plurality of elements that are set to zero is adapted based on at least one of the following: a number of digital modulation symbols in a DFTS-OFDM symbol, a modulation used, a signal to noise, SNR, ratio, a signal to interference and noise, SINR, ratio, a property of a frequency domain shaping filter, a symmetrical allocation of the bandwidth allocated for the data transmission within the configured channel, and an asymmetrical allocation of the bandwidth allocated for the data transmission within the configured channel.

15. The method of any one of Claims 10 to 14, wherein the modifying (1106) a quantity of elements in the first portion of the plurality of elements that are set to zero is modified based on switching from a quadrature phase shift keying, QPSK, modulation to a quadrature amplitude modulation, QAM with a number of bits per symbol higher than 2.

16. A device (1210, 1212, 1300, 1400) comprising: a digital baseband (100, 1312, 1414) of a communication transmitter (1318, 1412); processing circuitry (1302, 1402); memory (1310, 1404) coupled with the processing circuitry, wherein the memory includes instructions that when executed by the processing circuitry causes the device to perform operations comprising: set a first portion of a plurality of elements in a time variant filter to zero to obtain a truncated time variant filter; and generate an approximate discrete Fourier transform spread-orthogonal frequency division multiplexing, DFTS-OFDM, waveform based on filtering data symbols in time domain with the truncated time variant filter.

17. The device of Claim 16, wherein the time variant filter comprises a first matrix of elements that includes the first portion of the plurality of elements having non-zero values and the truncated time variant filter comprises a second diagonal dominant matrix of with the first portion of the plurality of elements having zero values.

18. The device of any one of Claims 16 to 17, wherein the memory includes instructions that when executed by the processing circuitry causes the device to perform further operations comprising: determine a quantity of the first portion of the plurality of elements in the time variant filter to set to zero based on at least one of (i) a sort and null process, and (ii) an equal bandwidth nulling process.

19. The device of Claim 18, wherein set a first portion of a plurality of elements in a time domain filter to zero to obtain a truncated time variant filter comprises: sort the plurality of elements in the time variant filter by amplitude value, retain a second portion of the elements in the time variant filter that respectively have an amplitude that is greater than or equal to a positive threshold amplitude value, set the first portion of the plurality elements in the time variant filter to zero, and form the truncated time variant filter using the first portion and second portion of the plurality of elements.

20. The device of Claim 18, wherein set a first portion of a plurality of elements in a time domain filter to zero to obtain a truncated time variant filter comprises: sort the plurality of elements in the time variant filter by amplitude value, retain a second portion of the elements in the time variant filter wherein the number of elements in the second portion of the elements is a fraction R of the total number of elements in the second matrix, set the first portion of the plurality elements in the time variant filter to zero, and form the truncated time variant filter using the first portion and second portion of the plurality of elements

21. The device of any one of Claims 19 and 20, wherein the positive threshold amplitude value and fraction R are based on a target level of performance decided by a communication system.

22. The device of Claim 18, wherein at least one of the positive threshold amplitude value or an identity of the second portion of the elements or fraction R is received from a node in a communications system.

23. The device of Claim 18, wherein set a first portion of a plurality elements in a time variant filter to zero to obtain a truncated time variant filter comprises, for each respective row of elements in the time variant filter: determine an element or elements in the respective row having a peak magnitude, retain a sub-set of elements having a non-zero value in the respective row that are symmetrically placed around the element or elements having the peak magnitude, and set a remainder of the sub-set of elements in the respective row to zero.

24. The device of any one of Claims 16 to 23, wherein the filtering data symbols in time domain with the truncated time variant filter comprises multiplying a vector of symbols from a digital modulation by the truncated time variant filter.

25. The device of any one of Claims 16 to 2224, further comprising: dynamically modify a quantity of elements in the first portion of the plurality of elements that are set to zero.

26. The device of any one of Claim 25, wherein modifying a quantity of elements in the first portion of the plurality of elements that are set to zero is based on a parameter.

27. The device of Claim 26, wherein the parameter comprises at least one of (i) a modulation parameter, (ii) a number of digital modulation symbols in a DFTS-OFDM symbol, (iii) a channel condition, (iv) an error vector magnitude, EVM, criterion, and (v) a property of a frequency domain shaping filter.

28. The device of any one of Claims 25 to 27, wherein modifying a quantity of elements in the first portion of the plurality of elements that are set to zero is based on at least one of an environmental condition and a scheduling decision.

29. The device of any one of Claims 25 to 28, wherein modify a quantity of elements in the first portion of the plurality of elements that are set to zero is adapted based on at least one of the following: a number of digital modulation symbols in a DFTS-OFDM symbol, a modulation used, a signal to noise, SNR, ratio, a signal to interference and noise, SINR, ratio, a property of a frequency domain shaping filter, a symmetrical allocation of the bandwidth allocated for the data transmission within the configured channel, and an asymmetrical allocation of the bandwidth allocated for the data transmission within the configured channel.

30. The device of any one of Claims 25 to 29, wherein modify a quantity of elements in the first portion of the plurality of elements that are set to zero is modified based on switching from a quadrature phase shift keying, QPSK, modulation to a quadrature amplitude modulation, QAM with a number of bits per symbol higher than 2.

31. A non-transitory computer readable medium (1310, 1404) including program code to be executed by processing circuitry (100, 1302, 1402) of a device (1210, 1212, 1300, 1400), whereby execution of the program code causes the program code to perform operations comprising: set a first portion of a plurality of elements in a time variant filter to zero to obtain a truncated time variant filter; and generate an approximate discrete Fourier transform spread-orthogonal frequency division multiplexing, DFTS-OFDM, waveform based on filtering data symbols in a time domain with the truncated time variant filter.

32. The non-transitory computer readable medium of Claim 30, the operations further comprising any of the operations of Claims 2 to 15.