TX beam nulling for suppressing SBFD interference

Abstract

Various embodiments disclosed herein provide a method for suppressing SubBand Full Duplex (SBFD) interference using transmission beam nulling in a network node or a user equipment (UE). In an embodiment from a perspective of a network node, a transmit nulling precoder can be designed that is based on self-interference channel coefficients corresponding to an uplink (UL) subband, while a downlink (DL) transmission precoder can be designed that is based on DL subband channel coefficients. These precoders can then be applied to a signal before transmission to one or more UEs. From the perspective of a UE, the transmit nulling precoder can be designed based on self-interference channel coefficients corresponding to a DL subband, while the UL transmission precoder is based on UL subband channel coefficients.

Description

TX BEAM NULLING FOR SUPPRESSING SBFD INTERFERENCE RELATED APPLICATIONS

[0001] This application claims the benefit of provisional patent application serial number 63 / 553,798, filed February 15, 2024, the disclosure of which is hereby incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present disclosure relates to a method for suppressing SubBand Full Duplex (SBFD) interference using transmission beam nulling in a network node or a user equipment in a wireless communications system. BACKGROUND

[0003] New radio (NR) standard in Third Generation Partnership Program (3GPP) is being designed to provide service for multiple use cases such as enhanced mobile broadband (eMBB), ultra-reliable and low latency communication (URLLC), and machine type communication (MTC). Each of these services has different technical requirements. For example, the general requirement for eMBB is high data rate with moderate latency and moderate coverage, while URLLC service requires a low latency and high reliability transmission but perhaps for moderate data rates.

[0004] An NR slot consists of several Orthogonal Frequency Division Multiplexing (OFDM) symbols, according to current agreements either 7 or 14 symbols (OFDM subcarrier spacing ≤ 60 kHz) and 14 symbols (OFDM subcarrier spacing > 60 kHz). Figure 1 shows a slot with 14 OFDM symbols. In Figure 1, ^^and ^^^^^denote the slot and OFDM symbol duration, respectively. Different Types of Duplex Communication Modes

[0005] To support the many types of targeted use cases with varying requirements, different duplex communication modes are discussed in 3GPP standardization. Moreover, the same device may be capable of operating using different duplex modes, for e.g., to achieve different overall communication performance based on its needs.

[0006] Transmission and reception from a wireless communication device, e.g., a base- station (BS) or a user equipment (UE) in a cellular system, can be multiplexed in the frequencydomain or in the time domain (or combinations thereof). The most relevant duplex modes are discussed below. Definitions of Different Duplex Modes

[0007] Frequency Division Duplex (FDD), as illustrated to the top left (202) in Figure 2, implies that transmission (TX) and reception (RX) take place in different, sufficiently separated carriers. Thus, FDD requires paired spectrum. In case of FDD operation, there are two carrier frequencies, one for uplink (UL) transmission and one for downlink (DL) transmission. At least with respect to the UE in a cellular communication system, FDD can be either full duplex (FD- FDD) or half duplex (HD-FDD). In the FD-FDD case, a UE can transmit and receive simultaneously, while in HD-FDD operation, the UE cannot transmit and receive simultaneously (the BS is still capable of simultaneous RX / TX though, e.g. receiving from one UE while simultaneously transmitting to another UE). In Long Term Evolution (LTE), a HD-FDD terminal is monitoring / receiving in the DL except when explicitly being instructed to transmit in a certain subframe.

[0008] Time Division Duplex (TDD), as illustrated to the top right (204) in Figure 2, shows that TX and RX take place within the same carrier in different, non-overlapping time slots. Thus, TDD can operate in unpaired spectrum. In case of TDD operation, there is only a single carrier frequency and UL and DL transmissions are always separated in time also on a cell basis. As the same carrier frequency is used for UL and DL transmission, both the BS and the UEs need to switch from TX to RX and vice versa. An essential aspect of any TDD system is to provide the possibility for a sufficiently large guard time where neither DL nor UL transmissions occur. This is required to avoid interference between UL and DL transmissions. For NR, this guard time is provided by special slots, which are split into three parts: symbols for DL, a guard period (GP), and symbols for UL. The remaining slots are either allocated to UL or DL transmission.

[0009] SubBand Full Duplex (SBFD), as illustrated to the bottom left (206) in Figure 2, is being studied in 3GPP Release 18 as a part of the 5G-Advanced standardization. In case of SBFD operation, a portion of a wide bandwidth carrier, termed subband(s), may be used for a different communication direction than that of the rest of the carrier. This is unlike the conventional TDD operation wherein the entire bandwidth of the carrier is always used either for DL or UL. SBFD operation can also be performed across different carriers within the same frequency band, wherein one or more carriers within a frequency band may be used for a different communication direction than that of the other carriers, which is again unlike conventional TDD operation wherein all carriers within a frequency band are always used for thesame communication direction. In the 3GPP Release 18 study, the scope has been limited such that during SBFD operation, only BSs transmit DL and receive UL simultaneously using corresponding non-overlapping subbands. An individual UE is scheduled in only one direction (DL or UL) at a time, following conventional HD TDD operation, referred to as HD-SBFD. However, for future releases such as Release 19, SBFD operation at UEs is also being discussed as a potential study topic, referred to as SBFD.

[0010] Single frequency full duplex (SFFD), as illustrated to the bottom right (208) in Figure 2, has also been proposed to be studied in 3GPP standardization. It was discussed but excluded from the scope of Release 18, and it is now again being discussed during scoping discussions for Release 19. In case of SFFD operation, the entire bandwidth of the same carrier in a single carrier system or all carriers in a multi-carrier system can be simultaneously used for DL and UL operations. In other words, the same time and frequency resources can be used for both TX and RX at the same device. Similar to SBFD operation, SFFD operation is also being discussed as a potential study topic for both BSs and UEs SBFD Self Interference

[0011] Since the gNB transmits on the DL while at the same time receiving on the UL, there is the risk of strong self-interference. The self-inference can be intra-sector (i.e., from one Tx panel to an Rx panel in the same sector) or inter-sector (i.e., Tx in one sector interferes with reception in another sector at the same site). There can in principle also be inter-site DL-to-UL interference, which in the context of the present disclosure will also be referred to as self- interference for simplicity / brevity in the descriptions. In an ideal situation with no RF / analog imperfections in the transmitter or receiver, the fact that DL and UL are transmitted on different subbands, combined with the orthogonality between OFDM subcarriers, will effectively lead to no self-interference between Tx and Rx. However, in real equipment with imperfections, there will be self-interference through two mechanisms: 1. The Tx signal is distorted due to transmitter-side imperfections, in particular non- linearities in the power amplifier (PA). This will lead to power being transmitted also in the UL subband, and hence cause interference to the desired UL signal. 2. The receiver analog components, e.g. the low-noise amplifier (LNA), have non- linearities. This makes the receiver capture power also from the DL subband.

[0012] These two effects are illustrated in Figure 3.Tx-side beam nulling

[0013] One way to reduce the self-interference is to adjust the precoder weights in the transmitter to create nulls or near-nulls at the locations of the receiver antenna elements. In other words, instead of using the precoder that is optimal for DL transmission, one uses a slightly different precoder. This means that the power transmitted in the desired DL direction will be reduced, but if this reduction is small, the overall system performance may still be improved if the self-interference reduction is large enough.

[0014] Take single-stream transmission as an example. Suppose the optimal DL precoder isdenoted by a ^ × 1 column vector ^(^) without considering the self-interference issues for asubcarrier ^. A signal ^(^) for subcarrier ^ is transmitted over the ^ antenna ports as: ^ ^(^) ^(^) Eqn.1 where ^ is desired level.a× precoder ^(^) tosuppress the self-interference. That is, the signal is transmitted over the ^ antenna ports as: ^ ^(^) ^(^) ^(^) Eqn.2

[0016] One way to design the nulling precoder is via regularized linear projection. Let •^(^) be the ^ × ^ self-interference channel coefficient matrix for subcarrier ^• ^ be an ^ × ^ identity matrix• ^ is a small number determining the level of nulling to use

[0017] Then the nulling precoder can be computed as ^(^) = ^ − ^(^)^(^(^)^(^)^ + ^^)^^^(^) Eqn. 3where ^parameter ^ controls the trade-off between how much the self-interference is suppressed and how much the transmitted power in the desired Tx direction is suppressed.

[0018] Note that while the expression for ^(^) does not explicitly depend on ^(^), it may still indirectly depend on ^(^), since it may be desirable to tune ^ differently depending on the beam direction defined by ^(^). A transmitter structure with nulling is illustrated in Figure 4.

[0019] There are more advanced methods, and also methods for multi-stream transmission (multiple beam directions). In more advanced methods, the nulling matrix may depend explicitly on ^(^).

[0020] Since the self-interference channel (and possibly also the Tx precoder) is typically frequency-selective, the nulling matrix is typically frequency-dependent, e.g., calculated and applied per subcarrier or a group of subcarriers.SUMMARY

[0021] Various embodiments disclosed herein provide for a method for suppressing SubBand Full Duplex (SBFD) interference using transmission beam nulling in a network node or a user equipment (UE). In an embodiment from a perspective of a network node, a transmit nulling precoder can be designed that is based on self-interference channel coefficients corresponding to an uplink (UL) subband, while a downlink (DL) transmission precoder can be designed that is based on DL subband channel coefficients. These precoders can then be applied to a signal before transmission to one or more UEs. From the perspective of a UE, the transmit nulling precoder can be designed based on self-interference channel coefficients corresponding to a DL subband, while the UL transmission precoder is based on UL subband channel coefficients.

[0022] In an aspect, a method is provided that is performed by a network node for performing transmit nulling to suppress interference in a Full Duplex (FD) transmission with one or more UEs which can include applying, to a signal, a transmit nulling precoder that is designed based on self-interference channel coefficients corresponding to an UL subband. The method can also include applying, to the signal, a DL transmission precoder that is designed based on DL subband channel coefficients and transmitting the signal to the one or more UEs.

[0023] In an embodiment, the DL transmission precoder is determined based on a regularized zero forcing beamforming design. In an embodiment, the transmit nulling precoder is based on regularized linear projection. In an embodiment, the DL transmission precoder and the transmit nulling precoder are jointly based on a regularized zero forcing beamforming design. In an embodiment, the self-interference channel coefficients correspond to a center subcarrier of the UL subband. In an embodiment, a transmit nulling precoder for subcarrier ^^is based on self-interference channel coefficients corresponding to subcarrier ^^, where subcarrier ^^depends on a subcarrier ^^, wherein if ^^is higher than the UL subband, then ^^is a highest subcarrier in the UL subband; if ^^is lower than the UL subband, then ^^is a lowest subcarrier in the UL subband; if ^^is higher than the UL subband, then ^^is set to a subcarrier in a higher half of the UL subband; if ^^is lower than the UL subband, then ^^is set to a subcarrier in a lower half of the UL subband; if ^^is higher than the UL subband, then ^^is set to a subcarrier with a fixed frequency separation of ∆^ from ^^; or if ^^is lower than the UL subband, then ^^is set to a subcarrier with a fixed frequency separation of ∆^ from ^^. In an embodiment, the transmit nulling precoder is designed based on self-interference channel coefficients corresponding to a DL subband. In an embodiment, the transmit nulling precoder comprises a nulling matrix ^ that is constant across the DL subband, and the DL transmission precodervaries across the DL subband. In an embodiment, the transmit nulling precoder comprises a nulling matrix ^ that is constant across the DL subband, and the DL transmission precoder remains the same across the DL subband. In an embodiment, the transmit nulling precoder is based on information about transmission side imperfections comprising power amplifier non- linearities. In an embodiment, self-interference associated with the self-interference channel coefficients is based on at least one of intra-sector interference, inter-sector interference, and inter-site interference.

[0024] In an aspect, a network node is provided for performing transmit nulling to suppress interference in FD transmission with one or more UEs. The network node includes processing circuitry configured to apply, to a signal, a transmit nulling precoder that is designed based on self-interference channel coefficients corresponding to a UL subband. The processing circuitry is also configured to apply, to the signal, a DL transmission precoder that is designed based on DL subband channel coefficients and transmit the signal to the one or more UEs.

[0025] In an aspect, a method is performed by a UE for performing transmit nulling to suppress interference in a FD transmission with a network node, where the method includes applying, to a signal, a transmit nulling precoder that is designed based on self-interference channel coefficients corresponding to a DL subband. The method also includes applying, to the signal, a UL transmission precoder that is designed based on UL subband channel coefficients and transmitting the signal to the network node.

[0026] In an embodiment, the UL transmission precoder is determined based on a regularized zero forcing beamforming design. In an embodiment, the transmit nulling precoder is based on regularized linear projection. In an embodiment, the UL transmission precoder and the transmit nulling precoder are jointly based on a regularized zero forcing beamforming design. In an embodiment, the self-interference channel coefficients correspond to a center subcarrier of the DL subband. In an embodiment, a transmit nulling precoder for subcarrier ^^is based on self-interference channel coefficients corresponding to subcarrier ^^, where subcarrier ^^depends on a subcarrier ^^, wherein if ^^is higher than the DL subband, then ^^is a highest subcarrier in the DL subband; if ^^is lower than the DL subband, then ^^is a lowest subcarrier in the DL subband; if ^^is higher than the DL subband, then ^^is set to a subcarrier in a higher half of the DL subband; if ^^is lower than the DL subband, then ^^is set to a subcarrier in a lower half of the DL subband; if ^^is higher than the DL subband, then ^^is set to a subcarrier with a fixed frequency separation of ∆^ from ^^; or if ^^is lower than the DL subband, then ^^is set to a subcarrier with a fixed frequency separation of ∆^ from ^^. In an embodiment, the transmit nulling precoder is designed based on self-interference channel coefficientscorresponding to a UL subband. In an embodiment, the transmit nulling precoder comprises a nulling matrix ^ that is constant across the UL subband, and the UL transmission precoder varies across the UL subband. In an embodiment, the transmit nulling precoder comprises a nulling matrix ^ that is constant across the UL subband, and the UL transmission precoder remains the same across the UL subband. In an embodiment, the transmit nulling precoder is based on information about transmission side imperfections comprising power amplifier non- linearities. In an embodiment, self-interference associated with the self-interference channel coefficients is based on at least one of intra-sector interference, inter-sector interference, and inter-site interference.

[0027] In an aspect, a UE is provided for performing transmit nulling to suppress interference in FD transmission with a network node. The UE includes processing circuitry configured to apply, to a signal, a transmit nulling precoder that is designed based on self- interference channel coefficients corresponding to an DL subband. The processing circuitry is also configured to apply, to the signal, a UL transmission precoder that is designed based on UL subband channel coefficients and transmit the signal to the network node. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0029] Figure 1 depicts an exemplary New Radio (NR) slot in accordance with some embodiments of the present disclosure;

[0030] Figure 2 depicts exemplary types of duplex communication modes in accordance with some embodiments of the present disclosure;

[0031] Figure 3 depicts exemplary gNB self-interference due to non-linearities in accordance with some embodiments of the present disclosure;

[0032] Figure 4 depicts an exemplary transmit-receive (TX-RX) chain in accordance with some embodiments of the present disclosure;

[0033] Figure 5 depicts an example of using the self-interference channel coefficients corresponding to center subcarrier / frequency of the uplink (UL) subband for joint beamforming or nulling precoder design in accordance with some embodiments of the present disclosure;

[0034] Figure 6 depicts an example of using the self-interference channel coefficients corresponding to subcarrier / frequency of the uplink (UL) subband for joint beamforming ornulling precoder design with dependence on a subcarrier where the frequency is higher than the UL subband in accordance with some embodiments of the present disclosure;

[0035] Figure 7 depicts an example of using the self-interference channel coefficients corresponding to subcarrier / frequency of the uplink (UL) subband for joint beamforming or nulling precoder design with dependence on a subcarrier where the frequency is lower than the UL subband in accordance with some embodiments of the present disclosure;

[0036] Figure 8 depicts an example of using the self-interference channel coefficients corresponding to using the self-interference channel coefficients corresponding to subcarrier / frequency of the UL subband for joint beamforming or nulling precoder design with dependence on the subcarrier / frequency for DL transmissions where the frequency is higher than the UL subband in accordance with some embodiments of the present disclosure;

[0037] Figure 9 depicts an example of using the self-interference channel coefficients corresponding to using the self-interference channel coefficients corresponding to subcarrier / frequency of the UL subband for joint beamforming or nulling precoder design with dependence on the subcarrier / frequency for DL transmissions where the frequency is lower than the UL subband in accordance with some embodiments of the present disclosure;

[0038] Figure 10 depicts an example of using the self-interference channel coefficients corresponding to subcarrier / frequency of the UL subband for joint beamforming or nulling precoder design with dependence on the subcarrier / frequency for DL transmissions where the frequency is higher than the UL subband in accordance with some embodiments of the present disclosure;

[0039] Figure 11 depicts an example of using the self-interference channel coefficients corresponding to subcarrier / frequency of the UL subband for joint beamforming or nulling precoder design with dependence on the subcarrier / frequency for DL transmissions where the frequency is lower than the UL subband in accordance with some embodiments of the present disclosure;

[0040] Figure 12 is an exemplary graph showing frequency independent (constant) nulling performing with respect to varying nulling in accordance with some embodiments of the present disclosure;

[0041] Figure 13 is another exemplary graph showing frequency independent (constant) nulling performing with respect to varying nulling in accordance with some embodiments of the present disclosure;

[0042] Figure 14 is a flowchart of a method for performing by a network node transmit nulling to suppress interference in a SubBand Full Duplex (SBFD) transmission in accordance with some embodiments of the present disclosure;

[0043] Figure 15 is a flowchart of a method for performing by a User Equipment transmit nulling to suppress interference in a SubBand Full Duplex (SBFD) transmission in accordance with some embodiments of the present disclosure;

[0044] Figure 16 shows an example of a communication system in accordance with some embodiments of the present disclosure;

[0045] Figure 17 shows a User Equipment device (UE) in accordance with some embodiments of the present disclosure;

[0046] Figure 18 shows a network node in accordance with some embodiments of the present disclosure;

[0047] Figure 19 is a block diagram of a host, which may be an embodiment of the host of Figure 16, in accordance with various aspects of the present disclosure described herein; and

[0048] Figure 20 is a block diagram illustrating a virtualization environment in which functions implemented by some embodiments of the present disclosure may be virtualized. DETAILED DESCRIPTION

[0049] The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.

[0050] 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.

[0051] There currently exist certain challenge(s). Traditionally, the nulling is calculated per subcarrier (or PRB) based on the transmit (Tx) precoder and self-interference channel ^ in the downlink (DL) subband, which is how conventional interference aware beamforming is designed. More specifically, when computing the DL transmission precoder ^(^) and the nulling precoder ^(^) for a specific subcarrier or group of subcarriers, the DL channel coefficients and the self-interference channel coefficients are taken from the same subcarrier frequency ^ for the DL signal.

[0052] This will reduce the self-interference in the DL subband, which may indirectly reduce the self-interference in the uplink (UL) subband. However, it does not target suppression of self-interference in the UL subband effectively, which would have been beneficial.

[0053] Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. The present disclosure provides a method to perform Tx nulling considering the self-interference in the UL subband directly. In particular: • In some embodiments, the Tx nulling precoder and the DL transmission precoder are designed separately. The Tx nulling precoder is designed using self-interference channel coefficients corresponding to the UL subband while the DL transmission precoder is designed using the DL subband channel coefficients. • In some embodiments, the Tx nulling is frequency-independent, as this has been shown to give good performance in link simulations. Said frequency-independent TX nulling can be designed using self-interference channel coefficients corresponding to the UL subband. • In some embodiments, a joint precoder is designed to achieve both high DL transmission performance and low self-interference. Said joint precoder design incorporates both the DL subband channel coefficients and self-interference channel coefficients corresponding to the UL subband.

[0054] In some (or all) embodiments, the impact of Tx-side and / or Receive (Rx)-side imperfections such as the power amplifier (PA) non-linearities are considered.

[0055] It is to be appreciated that while reference is made in the disclosure to a network node or gNB performing these techniques, the same techniques are applicable to a UE performing TX nulling, except that UL and DL are switched. An example of this is provided in the flowchart with regard to Figure 15.

[0056] In some embodiments, the Tx nulling precoder and the DL transmission precoder are designed separately. The Tx nulling precoder is designed using self-interference channel coefficients corresponding to the UL subband while the DL transmission precoder is designed using the DL subband channel coefficients.

[0057] In some embodiments, the Tx nulling is frequency-independent, as this has been shown to give good performance in link simulations. Said frequency-independent TX nulling is designed using self-interference channel coefficients corresponding to the UL subband.

[0058] In some embodiments, a joint precoder is designed to achieve both high DL transmission performance and low self-interference. Said joint precoder design incorporates boththe DL subband channel coefficients and self-interference channel coefficients corresponding to the UL subband.

[0059] In some embodiments, frequency independent Tx nulling is performed, i.e. applying the same nulling in all transmitted subcarriers.

[0060] In some embodiments, partly frequency independent Tx nulling is performed, i.e. applying the same nulling in some parts of the transmitted subcarriers.

[0061] In some embodiments, taking Tx-side and / or Rx-side imperfections into account is performed when calculating / applying Tx nulling.

[0062] In some embodiments, calculating Tx nulling for use in one (or multiple) subcarrier(s) based on conditions in one (or multiple) other subcarrier(s) is performed.

[0063] In some embodiments, calculating Tx nulling for a subcarrier in the UL band and applying that nulling in the DL band is performed.

[0064] Certain embodiments may provide one or more of the following technical advantage(s) by employing these techniques, including achieving the reduction of DL-to-UL interference (and hence better UL performance) without (or with minimal) negative impact on DL performance.

[0065] In an embodiment, the DL transmission precoder and nulling precoder design use channel coefficients correspond to different subcarriers / frequencies. Let: •^(^^) be the ^ × ^ DL channel coefficient matrix for subcarrier ^^ to the UE, where ^is determined by the number of antenna ports and capability of the UE receiving the DL transmission. oFor single-stream DL transmission, ^ = 1.o For multi-stream DL transmission, ^ > 1.• ^(^^) be the ^ × ^ self-interference channel coefficient matrix for subcarrier ^^• ^ be an ^ × ^ identity matrix

[0066] In a first exemplary embodiment, the DL transmission precoder (^^) is designed based on the channel coefficients correspond to the DL transmission subcarriers / frequencies ^^. The nulling precoder ^(^^) is designed based on the self-interference channel coefficients corresponding to subcarriers / frequencies ^^located in the UL subband.

[0067] As a nonlimiting exemplary embodiment, the DL transmission precoder (^^) is designed via the regularized zero forcing beamforming approach: (^ ) = (^(^ )^^(^ ) + ^ ^)^^^( ^^ ^ ^ ^ ^^) Eqn. 4zero forcing to use.

[0068] As a nonlimiting exemplary embodiment, the nulling precoder ^(^^) is designed based on regularized linear projection: ^(^ ) = ^^ ( ^ ( ^)^^ )^^^ ^ − ^(^ ) ^(^ )^ ^ + ^ ^ ^(^^) Eqn. 5where ^^is a coefficient the level of nulling to use.precoder design approach, the ^ × 1 signal !(^^) is transmitted over the ^ antenna ports as:^ ^(^^) ^(^^) !(^^) Eqn.6 where ^ is a factor such the transmitted signal power is at the desired level. embodiment, joint precoder design for both DL transmissioncan be computed via, for example, the regularized zero forcing approach. The DL transmission aims to transmit a ^ × 1 vector !(^^) to the UE whilesuppressing the self-interference. The joint precoder ", which is a ^ × ^ matrix, can becomputed as: "(^^) = # ^$% ^(^^)^^(^^) + ^ ^^^^$& ^(^^) ^(^^) + ^'^(^^) Eqn.7. and self-interference suppression. The ^ × 1 signal !(^^) is transmitted over the ^ antenna ports as:^ "(^^) !(^^) Eqn.8^ at the desired level.

[0071] In a further exemplary embodiment, the self-interference channel coefficients corresponding to center subcarrier / frequency of the UL subband: ^^ = ^( Eqn. 9where ^(is the center subcarrier / frequency of the UL subband. This is illustrated in Figure 5.

[0072] In the separate precoder design approach, the nulling precoder becomes frequency independent: ^(^^) = ^.

[0073] In the joint precoder design approach, the computation simplifies to "(^^) = # ^ ^(^^)^^(^^) + ^ ^(^ ^^^() ^(^() + ^'^(^^)^Eqn.10^^for self- interference channel coefficients depends on the subcarrier / frequency ^^for DL transmission precoder. For example:

[0075] If ^^is higher than the UL subband, then ^^is the highest subcarrier / frequency in the UL subband. This is illustrated in Figure 6.

[0076] If ^^is lower than the UL subband, then ^^is the lowest subcarrier / frequency in the UL subband. This is illustrated in Figure 7.

[0077] If ^^is higher than the UL subband, then ^^is the set to a subcarrier / frequency in the higher half of the UL subband. For example: ^^ = ^( + )*+, Eqn. 11where *+,is the bandwidth of the UL subband, and ) is a constant.

[0078] For example, ) could be set to 1 / 6 such that ^^is 1 / 3 of the UL subband bandwidth below the highest subcarrier / frequency in the UL subband. This is illustrated in Figure 8.

[0079] If ^^is lower than the UL subband, then ^^is the set to a subcarrier / frequency in the lower half of the UL subband. For example: ^^ = ^( − )*+, Eqn. 12

[0080] For example, ) could be set to 1 / 6 such that ^^is 1 / 3 of the UL subband bandwidth above the lowest subcarrier / frequency in the UL subband. This is illustrated in Figure 9.

[0081] If ^^is higher than the UL subband, then ^^is the set to a subcarrier / frequency with a fixed frequency separation of ∆^ from the DL transmission subcarrier / frequency. For example: ^^ = max(^^ − ∆^, ^() Eqn. 13where the maximum operation is to ensure ^^does not fall below the center frequency / subcarrier of the UL subband. This is illustrated in Figure 10.

[0082] If ^^is lower than the UL subband, then ^^is the set to a subcarrier / frequency with a fixed frequency separation of ∆^ from the DL transmission subcarrier / frequency. For example: ^^ = min(^^ + ∆^, ^() Eqn. 14where the minimum operation is to ensure ^^does not fall above the center frequency / subcarrier of the UL subband. This is illustrated in Figure 11.

[0083] In any of the above exemplary embodiments, multi-user DL transmission can be performed, i.e., the same subcarrier / frequency is used to transmit separate signals to different UEs. Using two user DL transmission as a nonlimiting illustrating example. Let •^3(^^) be the ^^ × ^ DL channel coefficient matrix for subcarrier ^^ to UE 1, where ^^is determined by the number of antenna ports and capability of the UE 1 receiving the DL transmission. •^4(^^) be the ^5 × ^ DL channel coefficient matrix for subcarrier ^^ to UE 2, where ^5is determined by the number of antenna ports and capability of the UE 2 receiving the DL transmission.

[0084] In the separate precoder design approach, the DL precoder for the two UEs can be computed as: (^ ) = (^ (^ )^^ (^ ) + ^ (^ )^^ )^^ ^3 ^ 3 ^ 3 ^ 4 ^ 4(^^) + ^^^ ^3(^^) Eqn. 15

[0085] In the joint precoder design approach, the joint precoder for the two UEs can be computed as Eqn.17 and Eq.18: ^ "3(^^) 1= 6^ ^3(^^) ^3(^^) 1^ ^+ ^4(^ ^ 1 ^^) ^4(^^) + ^(^^) ^(^^) + ^7 ^ ^^^^^ ^ 3^(^))^, still vary. In another variant, the product ^8 is made constant across frequencies, e.g. by using a fixed 8.

[0087] As mentioned above, in some embodiments, the Tx nulling is selected to be frequency-independent. Such embodiments are motivated by the fact that it has been shown to give good performance in link simulations, see Figure 12 and Figure 13.

[0088] Figure 12 is an example of how frequency-independent (“constant”) nulling performs well. In this example the nulling used across both downlink bands are calculated based on the center of the uplink band.

[0089] Figure 13 is Example of how frequency-independent nulling performs well. This is the exact same case as in Figure 12 but showing received interference power. Basing the nulling on calculations from the center of the UL band results in suppressed interference power in the UL band which translates to the better performance shown in Figure 12.

[0090] The following embodiments can contain a certain level of overlap with the more technically described embodiments above.

[0091] In some embodiments, the Tx nulling is selected to be frequency-independent only in subbands of the used frequency range. For example, in the case of two separate non-contiguous DL bands, each of the DL bands can use different nulling matrices ^ constant across each separate subband.

[0092] In some embodiments, the Tx nulling is based only on estimates and / or measurements of the channel(s) in the DL subband(s), since it may be easier to measure the channel in this subband. For example, in the case of frequency-independent nulling, it may be based on the channel near the edge of the DL subband that is closest to the UL subband.

[0093] In another embodiment, Tx nulling is based solely or also on estimates and / or measurements of channel(s) in the UL subband. For example, in the case of frequency- independent nulling, the Tx nulling may be based on the channel at the center or close to the center of the UL subband.

[0094] In some (or all) embodiments, the impact of Tx-side imperfections such as the PA non-linearities are considered. In some embodiments, knowledge about the behavior of the non- linearities are considered and / or compensated for.

[0095] In some (or all) embodiments, the impact of Rx-side imperfections such as noise from a LNA are considered. In some embodiments, knowledge about the behavior of a LNA are considered and / or compensated for. For example, the amount of noise could affect how the Tx nulling is selected and / or calculated.

[0096] In another embodiment, the applied Tx nulling is based on Tx nulling calculated from multiple different subcarriers that are combined using different or same weights.

[0097] In some embodiments, single-stream DL transmission to single UE is considered, (rank=1). With a frequency-independent precoder, the beam shape will then in principle be the same across both DL and UL subbands, if variations in non-linearities between PAs are neglected. This fact may be utilized to simplify the derivation of effective tx-nulling matrices for rank 1.

[0098] In some embodiments, multi-stream DL transmission is considered, (rank>1).

[0099] In some embodiments, different variants of the earlier embodiments are used for intra-sector and inter-sector Tx nulling (and / or inter-site).

[0100] As discussed above, in practical situations, a given Tx beam (precoder), even if frequency-independent, will not necessarily result in the same beam forming / nulling for both the DL and UL subbands at the BS receiver. One may then trade off nulling efficiency in the UL and DL subbands, depending on the relative importance of UL- vs DL-subband interference in the UL receiver: • For example, suppose the BS receiver has an analog filtering solution implemented to suppress the interference power in the DL subbands. In that case, the receiver may need assistance from TX nulling mainly to suppress the interference power in the UL subbands and thereby the precoding algorithm could apply more weights to the UL subband nulling than to the DL subband nulling. • On the other hand, there may be cases when TX nulling could mainly be required to suppress the interference power in the DL subbands to reduce the blocking power to not only protect the LNA but also to reduce the corresponding impact to the UL subband from LNA non-linearities - in this case, the DL subband precoding could be weighed higher. • Thus, it could be beneficial to know and leverage the information about how the precoder behaves for the different subbands.

[0101] In the case of rank-1 transmission, and if wide-band (frequency-independent) precoder is used, then the signal on different Tx antennas differ only by a phase factor, i.e. if all PAs are identical, the UL beam shape will be same as the DL beam shape (except for the fact that the slightly different wavelength on different subcarriers makes the antenna-distance-to- wavelength ratio slightly different. • In some embodiments, nulling is therefore performed differently depending on these aspects (number streams, whether wide-band precoder is used or not, how large variation between PAs can be expected, the change of wavelength over the frequency band etc.)

[0102] Figure 14 is a flowchart of a method for performing by a network node transmit nulling to suppress interference in a SubBand Full Duplex (SBFD) transmission in accordance with some embodiments of the present disclosure;

[0103] The method can begin at 1402 where the method includes applying (1412, to a signal, a transmit nulling precoder that is designed based on self-interference channel coefficients corresponding to an UL subband.

[0104] In an embodiment, the transmit nulling precoder is based on regularized linear projection.

[0105] At 1404, the methods include applying to the signal a DL transmission precoder that is designed based on DL subband channel coefficients.

[0106] In an embodiment, the DL transmission precoder is determined based on a regularized zero forcing beamforming design.

[0107] In an embodiment, the DL transmission precoder and the transmit nulling precoder are jointly based on a regularized zero forcing beamforming design.

[0108] In an embodiment, the self-interference channel coefficients correspond to a center subcarrier of the UL subband.

[0109] In an embodiment, a subcarrier ^^for self-interference channel coefficients depends on a subcarrier ^^for the DL transmission precoder, wherein: • if ^^is higher than the UL subband, then ^^is a highest subcarrier in the UL subband; • if ^^is lower than the UL subband, then ^^is a lowest subcarrier in the UL subband; • if ^^is higher than the UL subband, then ^^is the set to a subcarrier in a higher half of the UL subband; • if ^^is lower than the UL subband, then ^^is the set to a subcarrier in a lower half of the UL subband; • if ^^is higher than the UL subband, then ^^is the set to a subcarrier with a fixed frequency separation of ∆^ from ^^; or • if ^^is lower than the UL subband, then ^^is the set to a subcarrier with a fixed frequency separation of ∆^ from ^^.

[0110] At 1406, the method includes transmitting the signal to the one or more UEs.

[0111] In an embodiment, the transmitting the signal to the one or more UEs comprises a multi-user DL transmission wherein a single subcarrier is used to transmit separate transmissions to different UEs.

[0112] In an embodiment, the transmit nulling precoder comprises a nulling matrix ^ that is constant across an entire DL subband, and the transmit nulling precoder varies across the entire DL subband.

[0113] In an embodiment, the transmit nulling precoder comprises a nulling matrix ^ that is constant across an entire DL subband, and the transmit nulling precoder remains the same across the entire DL subband.

[0114] Figure 15 is a flowchart of a method for performing by a User Equipment transmit nulling to suppress interference in a SubBand Full Duplex (SBFD) transmission in accordance with some embodiments of the present disclosure.

[0115] The method begins at step 1502 with applying to a signal, a transmit nulling precoder that is designed based on self-interference channel coefficients corresponding to a DL subband.

[0116] In an embodiment, the self-interference channel coefficients correspond to a center subcarrier of the DL subband.

[0117] At 1504, the method includes applying, to the signal, an UL transmission precoder that is designed based on UL subband channel coefficients.

[0118] In an embodiment, a subcarrier ^^for self-interference channel coefficients depends on a subcarrier ^^for the DL transmission precoder, wherein: • if ^^^^is higher than the DL subband, then ^^is a highest subcarrier in the DL subband; • ^^is lower than the DL subband, then ^^is a lowest subcarrier in the DL subband; • if ^^is higher than the DL subband, then ^^is the set to a subcarrier in a higher half of the DL subband; • if ^^is lower than the DL subband, then ^^is the set to a subcarrier in a lower half of the DL subband; • if ^^is higher than the DL subband, then ^^is the set to a subcarrier with a fixed frequency separation of ∆^ from ^^; or • if ^^is lower than the DL subband, then ^^is the set to a subcarrier with a fixed frequency separation of ∆^ from ^^.

[0119] In an embodiment, the transmit nulling precoder comprises a nulling matrix ^ that is constant across an entire UL subband, and the transmit nulling precoder varies across the entire UL subband.

[0120] In an embodiment, the transmit nulling precoder comprises a nulling matrix ^ that is constant across an entire UL subband, and the transmit nulling precoder remains the same across the entire UL subband.

[0121] At 1506, the method includes transmitting the signal to the network node.

[0122] Figure 16 shows an example of a communication system 1600 in accordance with some embodiments.

[0123] In the example, the communication system 1600 includes a telecommunication network 1602 that includes an access network 1604, such as a Radio Access Network (RAN), and a core network 1606, which includes one or more core network nodes 1608. The access network 1604 includes one or more access network nodes, such as network nodes 1610A and 1610B (one or more of which may be generally referred to as network nodes 1610), or any other similar Third Generation Partnership Project (3GPP) access nodes or non-3GPP Access Points (APs). The network nodes 1610 can perform the TX beam nulling for suppressing SBFD interference as disclosed herein, and the method performed in Figure 14. 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 1602 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network 1602 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 1602, including one or more network nodes 1610 and / or core network nodes 1608.

[0124] 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 A1, F1, W1, E1, 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 beimplemented 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 O-2 interface defined by the O-RAN Alliance or comparable technologies. The network nodes 1610 facilitate direct or indirect connection of User Equipment (UE), such as by connecting UEs 1612A, 1612B, 1612C, and 1612D (one or more of which may be generally referred to as UEs 1612) to the core network 1606 over one or more wireless connections.

[0125] 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 1600 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 1600 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0126] The UEs 1612 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 1610 and other communication devices. Similarly, the network nodes 1610 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 1612 and / or with other network nodes or equipment in the telecommunication network 1602 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 1602. The UES 1612 can perform the TX beam nulling for suppressing SBFD interference as disclosed herein, and the method performed in Figure 15.

[0127] In the depicted example, the core network 1606 connects the network nodes 1610 to one or more hosts, such as host 1616. 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 1606 includes one more core network nodes (e.g., core network node 1608) 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 1608. 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).

[0128] The host 1616 may be under the ownership or control of a service provider other than an operator or provider of the access network 1604 and / or the telecommunication network 1602, and may be operated by the service provider or on behalf of the service provider. The host 1616 may host a variety of applications to provide one or more services. 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.

[0129] As a whole, the communication system 1600 of Figure 16 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system 1600 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 Second, Third, Fourth, or Fifth Generation (2G, 3G, 4G, or 5G) standards, or any applicable future generation standard (e.g., Sixth Generation (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.

[0130] In some examples, the telecommunication network 1602 is a cellular network that implements 3GPP standardized features. Accordingly, the telecommunication network 1602 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 1602. For example, the telecommunication network 1602 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) / massive Internet of Things (IoT) services to yet further UEs.

[0131] In some examples, the UEs 1612 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 1604 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 1604. Additionally, a UE may be configured for operating in single- or multi-Radio Access Technology (RAT) or multi-standard mode. For example, a UE may operate with any one or combination of WiFi, New Radio (NR), and LTE, i.e. being configured for Multi-Radio Dual Connectivity (MR-DC), such as Evolved UMTS Terrestrial RAN (E-UTRAN) NR - Dual Connectivity (EN-DC).

[0132] In the example, a hub 1614 communicates with the access network 1604 to facilitate indirect communication between one or more UEs (e.g., UE 1612C and / or 1612D) and network nodes (e.g., network node 1610B). In some examples, the hub 1614 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 1614 may be a broadband router enabling access to the core network 1606 for the UEs. As another example, the hub 1614 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 1610, or by executable code, script, process, or other instructions in the hub 1614. As another example, the hub 1614 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 1614 may be a content source. For example, for a UE that is a Virtual Reality (VR) headset, display, loudspeaker or other media delivery device, the hub 1614 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 1614 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 1614 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy IoT devices.

[0133] The hub 1614 may have a constant / persistent or intermittent connection to the network node 1610B. The hub 1614 may also allow for a different communication scheme and / or schedule between the hub 1614 and UEs (e.g., UE 1612C and / or 1612D), and between the hub 1614 and the core network 1606. In other examples, the hub 1614 is connected to the core network 1606 and / or one or more UEs via a wired connection. Moreover, the hub 1614 may be configured to connect to a Machine-to-Machine (M2M) service provider over the access network 1604 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 1610 while still connected via the hub 1614 via awired or wireless connection. In some embodiments, the hub 1614 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 1610B. In other embodiments, the hub 1614 may be a non-dedicated hub – that is, a device which is capable of operating to route communications between the UEs and the network node 1610B, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0134] Figure 17 shows a UE 1700 in accordance with some embodiments. As used herein, a UE refers to a device capable, configured, arranged, and / or operable to communicate wirelessly with network nodes and / or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, Voice over Internet Protocol (VoIP) phone, wireless local loop phone, desktop computer, Personal Digital Assistant (PDA), wireless camera, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, Laptop Embedded Equipment (LEE), Laptop Mounted Equipment (LME), smart device, wireless Customer Premise Equipment (CPE), vehicle, vehicle-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3GPP, including a Narrowband Internet of Things (NB-IoT) UE, a Machine Type Communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0135] A UE may support Device-to-Device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), Vehicle-to-Vehicle (V2V), Vehicle-to-Infrastructure (V2I), or Vehicle- to-Everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

[0136] The UE 1700 includes processing circuitry 1702 that is operatively coupled via a bus 1704 to an input / output interface 1706, a power source 1708, memory 1710, a communication interface 1712, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 17. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0137] The processing circuitry 1702 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 1710. The processing circuitry 1702 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 processing circuitry 1702 may include multiple Central Processing Units (CPUs).

[0138] In the example, the input / output interface 1706 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 speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE 1700. 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, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, 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.

[0139] In some embodiments, the power source 1708 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. The power source 1708 may further include power circuitry for delivering power from the power source 1708 itself, and / or an external power source, to the various parts of the UE 1700 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 1708. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 1708 to make the power suitable for the respective components of the UE 1700 to which power is supplied.

[0140] The memory 1710 may be or be configured to include memory such as Random Access Memory (RAM), Read Only Memory (ROM), Programmable ROM (PROM), ErasablePROM (EPROM), Electrically EPROM (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 1710 includes one or more application programs 1714, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 1716. The memory 1710 may store, for use by the UE 1700, any of a variety of various operating systems or combinations of operating systems.

[0141] The memory 1710 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 RAM (SDRAM), external micro-DIMM SDRAM, smartcard memory such as a tamper resistant module in the form of a Universal Integrated Circuit Card (UICC) including one or more Subscriber Identity Modules (SIMs), such as a Universal SIM (USIM) and / or Internet Protocol Multimedia Services Identity Module (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 a ‘SIM card.’ The memory 1710 may allow the UE 1700 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 1710, which may be or comprise a device-readable storage medium.

[0142] The processing circuitry 1702 may be configured to communicate with an access network or other network using the communication interface 1712. The communication interface 1712 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 1722. The communication interface 1712 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 UE or a network node in an access network). Each transceiver may include a transmitter 1718 and / or a receiver 1720 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 1718 and receiver 1720 may be coupled to one or more antennas (e.g., the antenna 1722) and may share circuit components, software, or firmware, or alternatively be implemented separately.

[0143] In the illustrated embodiment, communication functions of the communication interface 1712 may include cellular communication, WiFi communication, LPWANcommunication, data communication, voice communication, multimedia communication, short- range communications such as Bluetooth, NFC, 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 CDMA (WCDMA), GSM, LTE, NR, UMTS, WiMax, Ethernet, Transmission Control Protocol / Internet Protocol (TCP / IP), Synchronous Optical Networking (SONET), Asynchronous Transfer Mode (ATM), Quick User Datagram Protocol Internet Connection (QUIC), Hypertext Transfer Protocol (HTTP), and so forth.

[0144] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 1712, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0145] As another example, a UE comprises an actuator, a motor, or a switch related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or to a robotic arm performing a medical procedure according to the received input.

[0146] A UE, when in the form of an IoT device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application, and healthcare. Non-limiting examples of such an IoT device are a device which is or which is embedded in: a connected refrigerator or freezer, a television, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for Augmented Reality (AR) or VR, a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- oritem-tracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an IoT device comprises circuitry and / or software in dependence of the intended application of the IoT device in addition to other components as described in relation to the UE 1700 shown in Figure 17.

[0147] As yet another specific example, in an IoT scenario, a UE may represent a machine or other device that performs monitoring and / or measurements and transmits the results of such monitoring and / or measurements to another UE and / or a network node. The UE may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship, an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0148] In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g., by controlling an actuator) to increase or decrease the drone’s speed. The first and / or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator and handle communication of data for both the speed sensor and the actuators.

[0149] Figure 18 shows a network node 1800 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged, and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment in a telecommunication network. Examples of network nodes include, but are not limited to, APs (e.g., radio APs), Base Stations (BSs) (e.g., radio BSs, Node Bs, evolved Node Bs (eNBs), NR Node Bs (gNBs)), and O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O- CU).

[0150] Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an O-RAN access node), and / orRemote Radio Units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such RRUs may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a Distributed Antenna System (DAS).

[0151] Other examples of network nodes include multiple Transmission Point (multi-TRP) 5G access nodes, Multi-Standard Radio (MSR) equipment such as MSR BSs, network controllers such as Radio Network Controllers (RNCs) or BS Controllers (BSCs), Base Transceiver Stations (BTSs), transmission points, transmission nodes, Multi-Cell / Multicast Coordination Entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0152] The network node 1800 includes processing circuitry 1802, memory 1804, a communication interface 1806, and a power source 1808. The network node 1800 may be composed of multiple physically separate components (e.g., a NodeB component and an RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the network node 1800 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair may in some instances be considered a single separate network node. In some embodiments, the network node 1800 may be configured to support multiple RATs. In such embodiments, some components may be duplicated (e.g., separate memory 1804 for different RATs) and some components may be reused (e.g., a same antenna 1810 may be shared by different RATs). The network node 1800 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1800, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, Long Range Wide Area Network (LoRaWAN), Radio Frequency Identification (RFID), or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within the network node 1800.

[0153] The processing circuitry 1802 may comprise a combination of one or more of a microprocessor, controller, microcontroller, CPU, DSP, ASIC, FPGA, or any other suitable computing device, resource, or combination of hardware, software, and / or encoded logic operable to provide, either alone or in conjunction with other network node 1800 components, such as the memory 1804, to provide network node 1800 functionality.

[0154] In some embodiments, the processing circuitry 1802 includes a System on a Chip (SOC). In some embodiments, the processing circuitry 1802 includes one or more of Radio Frequency (RF) transceiver circuitry 1812 and baseband processing circuitry 1814. In some embodiments, the RF transceiver circuitry 1812 and the baseband processing circuitry 1814 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of the RF transceiver circuitry 1812 and the baseband processing circuitry 1814 may be on the same chip or set of chips, boards, or units.

[0155] The memory 1804 may comprise any form of volatile or non-volatile computer- readable memory including, without limitation, persistent storage, solid state memory, remotely mounted memory, magnetic media, optical media, RAM, ROM, mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD), or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device-readable, and / or computer-executable memory devices that store information, data, and / or instructions that may be used by the processing circuitry 1802. The memory 1804 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry 1802 and utilized by the network node 1800. The memory 1804 may be used to store any calculations made by the processing circuitry 1802 and / or any data received via the communication interface 1806. In some embodiments, the processing circuitry 1802 and the memory 1804 are integrated.

[0156] The communication interface 1806 is used in wired or wireless communication of signaling and / or data between a network node, access network, and / or UE. As illustrated, the communication interface 1806 comprises port(s) / terminal(s) 1816 to send and receive data, for example to and from a network over a wired connection. The communication interface 1806 also includes radio front-end circuitry 1818 that may be coupled to, or in certain embodiments a part of, the antenna 1810. The radio front-end circuitry 1818 comprises filters 1820 and amplifiers 1822. The radio front-end circuitry 1818 may be connected to the antenna 1810 and the processing circuitry 1802. The radio front-end circuitry 1818 may be configured to condition signals communicated between the antenna 1810 and the processing circuitry 1802. The radio front-end circuitry 1818 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry 1818 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of the filters 1820 and / or the amplifiers 1822. The radio signal may then be transmitted via the antenna 1810. Similarly, when receiving data, the antenna 1810 may collect radio signals whichare then converted into digital data by the radio front-end circuitry 1818. The digital data may be passed to the processing circuitry 1802. In other embodiments, the communication interface 1806 may comprise different components and / or different combinations of components.

[0157] In certain alternative embodiments, the network node 1800 does not include separate radio front-end circuitry 1818; instead, the processing circuitry 1802 includes radio front-end circuitry and is connected to the antenna 1810. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1812 is part of the communication interface 1806. In still other embodiments, the communication interface 1806 includes the one or more ports or terminals 1816, the radio front-end circuitry 1818, and the RF transceiver circuitry 1812 as part of a radio unit (not shown), and the communication interface 1806 communicates with the baseband processing circuitry 1814, which is part of a digital unit (not shown).

[0158] The antenna 1810 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 1810 may be coupled to the radio front-end circuitry 1818 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 1810 is separate from the network node 1800 and connectable to the network node 1800 through an interface or port.

[0159] The antenna 1810, the communication interface 1806, and / or the processing circuitry 1802 may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node 1800. Any information, data, and / or signals may be received from a UE, another network node, and / or any other network equipment. Similarly, the antenna 1810, the communication interface 1806, and / or the processing circuitry 1802 may be configured to perform any transmitting operations described herein as being performed by the network node 1800. Any information, data, and / or signals may be transmitted to a UE, another network node, and / or any other network equipment.

[0160] The power source 1808 provides power to the various components of the network node 1800 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 1808 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 1800 with power for performing the functionality described herein. For example, the network node 1800 may be connectable to an external power source (e.g., the power grid or an electricity outlet) via input circuitry or an interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 1808. As a further example, the power source 1808 may comprise a source of power in the form of a battery or battery packwhich is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0161] Embodiments of the network node 1800 may include additional components beyond those shown in Figure 18 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node 1800 may include user interface equipment to allow input of information into the network node 1800 and to allow output of information from the network node 1800. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 1800.

[0162] Figure 19 is a block diagram of a host 1900, which may be an embodiment of the host 1616 of Figure 16, in accordance with various aspects described herein. As used herein, the host 1900 may be or comprise various combinations of hardware and / or software including a standalone server, a blade server, a cloud-implemented server, a distributed server, a virtual machine, container, or processing resources in a server farm. The host 1900 may provide one or more services to one or more UEs.

[0163] The host 1900 includes processing circuitry 1902 that is operatively coupled via a bus 1904 to an input / output interface 1906, a network interface 1908, a power source 1910, and memory 1912. Other components may be included in other embodiments. Features of these components may be substantially similar to those described with respect to the devices of previous figures, such as Figures 17 and 18, such that the descriptions thereof are generally applicable to the corresponding components of the host 1900.

[0164] The memory 1912 may include one or more computer programs including one or more host application programs 1914 and data 1916, which may include user data, e.g. data generated by a UE for the host 1900 or data generated by the host 1900 for a UE. Embodiments of the host 1900 may utilize only a subset or all of the components shown. The host application programs 1914 may be implemented in a container-based architecture and may provide support for video codecs (e.g., Versatile Video Coding (VVC), High Efficiency Video Coding (HEVC), Advanced Video Coding (AVC), Moving Picture Experts Group (MPEG), VP9) and audio codecs (e.g., Free Lossless Audio Codec (FLAC), Advanced Audio Coding (AAC), MPEG, G.711), including transcoding for multiple different classes, types, or implementations of UEs (e.g., handsets, desktop computers, wearable display systems, and heads-up display systems). The host application programs 1914 may also provide for user authentication and licensing checks and may periodically report health, routes, and content availability to a central node, such as a device in or on the edge of a core network. Accordingly, the host 1900 may select and / orindicate a different host for Over-The-Top (OTT) services for a UE. The host application programs 1914 may support various protocols, such as the HTTP Live Streaming (HLS) protocol, Real-Time Messaging Protocol (RTMP), Real-Time Streaming Protocol (RTSP), Dynamic Adaptive Streaming over HTTP (DASH or MPEG-DASH), etc.

[0165] Figure 20 is a block diagram illustrating a virtualization environment 2000 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 2000 hosted by one or more of hardware nodes, such as a hardware computing 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 2000 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.

[0166] Applications 2002 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment 2000 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0167] Hardware 2004 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 2006 (also referred to as hypervisors or VM Monitors (VMMs)), provide VMs 2008A and 2008B (one or more of which may be generally referred to as VMs 2008), and / or perform any of the functions, features, and / or benefits described in relation with some embodiments described herein. The virtualization layer 2006 may present a virtual operating platform that appears like networking hardware to the VMs 2008.

[0168] The VMs 2008 comprise virtual processing, virtual memory, virtual networking, or interface and virtual storage, and may be run by a corresponding virtualization layer 2006.Different embodiments of the instance of a virtual appliance 2002 may be implemented on one or more of the VMs 2008, 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.

[0169] In the context of NFV, a VM 2008 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 2008, and that part of the hardware 2004 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs 2008, 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 2008 on top of the hardware 2004 and corresponds to the application 2002.

[0170] The hardware 2004 may be implemented in a standalone network node with generic or specific components. The hardware 2004 may implement some functions via virtualization. Alternatively, the hardware 2004 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 2010, which, among others, oversees lifecycle management of the applications 2002. In some embodiments, the hardware 2004 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 RAN or a base station. In some embodiments, some signaling can be provided with the use of a control system 2012 which may alternatively be used for communication between hardware nodes and radio units.

[0171] Although the computing devices described herein (e.g., UEs, network nodes, hosts) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing 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 network node, and / or performing one or more operations based onthe 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 computing 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 processing circuitry and the communication 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.

[0172] In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored 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 hardwired 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 computing device, but are enjoyed by the computing device as a whole and / or by end users and a wireless network generally.

[0173] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.

[0174] Some of the embodiments disclosed herein include:

[0175] Embodiment 1. A method performed by a network node (1610) for performing transmit nulling to suppress interference in a SubBand Full Duplex, SBFD, transmission, with one or more User Equipments, UEs, (1612) the method comprising applying (1402), to a signal, a transmit nulling precoder that is designed based on self-interference channel coefficients corresponding to an uplink, UL, subband; applying (1404), to the signal, a downlink, DL, transmission precoder that is designed based on DL subband channel coefficients; and transmitting (1406) the signal to the one or more UEs (1612).

[0176] Embodiment 2. The method of embodiment 1, wherein the DL transmission precoder is determined based on a regularized zero forcing beamforming design.

[0177] Embodiment 3. The method of any of embodiments 1 to 2, wherein the transmit nulling precoder is based on regularized linear projection.

[0178] Embodiment 4. The method of embodiment 1, wherein the DL transmission precoder and the transmit nulling precoder are jointly based on a regularized zero forcing beamforming design.

[0179] Embodiment 5. The method of any of embodiments 1 to 4, wherein the self- interference channel coefficients correspond to a center subcarrier of the UL subband.

[0180] Embodiment 6. The method of embodiment 1, wherein a transmit nulling precoder for subcarrier ^^is based on self-interference channel coefficients corresponding to subcarrier ^^where subcarrier ^^depends on a subcarrier ^^, wherein: • if ^^is higher than the UL subband, then ^^is a highest subcarrier in the UL subband; • if ^^is lower than the UL subband, then ^^is a lowest subcarrier in the UL subband; • if ^^is higher than the UL subband, then ^^is set to a subcarrier in a higher half of the UL subband; • if ^^is lower than the UL subband, then ^^is set to a subcarrier in a lower half of the UL subband; • if ^^is higher than the UL subband, then ^^is set to a subcarrier with a fixed frequency separation of ∆^ from ^^; or • if ^^is lower than the UL subband, then ^^is set to a subcarrier with a fixed frequency separation of ∆^ from ^^.

[0181] Embodiment 7. The method of any of embodiments 1 to 6, wherein the transmit nulling precoder is designed based on self-interference channel coefficients corresponding to a DL subband.

[0182] Embodiment 8. The method of any of embodiments 1 to 7, wherein the transmit nulling precoder comprises a nulling matrix ^ that is constant across a DL subband, and the DL transmission precoder varies across the DL subband.

[0183] Embodiment 9. The method of any of embodiments 1 to 7, wherein the transmit nulling precoder comprises a nulling matrix ^ that is constant across a DL subband, and the DL transmission precoder remains the same across the DL subband.

[0184] Embodiment 10. The method of any of embodiments 1 to 9, wherein the transmit nulling precoder is based on information about transmission side imperfections such as power amplifier non-linearities.

[0185] Embodiment 11. A network node (1610) for performing transmit nulling to suppress interference in a SubBand Full Duplex, SBFD, transmission, with one or more User Equipments, UEs, (1612) the network node (1610) comprising processing circuitry configured to: apply (1402) to a signal, a transmit nulling precoder that is designed based on self-interference channelcoefficients corresponding to an uplink, UL, subband; apply (1404), to the signal, a downlink, DL, transmission precoder that is designed based on DL subband channel coefficients; and transmit (1406) the signal to the one or more UEs (1612).

[0186] Embodiment 12. The network node (1610) of embodiment 11, wherein the processing circuitry is further configured to perform any of the methods of embodiments 2 to 10.

[0187] Embodiment 13. A method performed by a User Equipment device, UE, (1612) for performing transmit nulling to suppress interference in a SubBand Full Duplex, SBFD, transmission, with a network node (1610), the method comprising: applying (1502), to a signal, a transmit nulling precoder that is designed based on self-interference channel coefficients corresponding to a downlink, DL, subband; applying (1504), to the signal, an uplink, UL, transmission precoder that is designed based on UL subband channel coefficients; and transmitting (1506) the signal to the network node (1610).

[0188] Embodiment 14. The method of embodiment 13, wherein the UL transmission precoder is determined based on a regularized zero forcing beamforming design.

[0189] Embodiment 15. The method of any of embodiments 13 to 14, wherein the transmit nulling precoder is based on regularized linear projection.

[0190] Embodiment 16. The method of embodiment 13, the UL transmission precoder and the transmit nulling precoder are jointly based on a regularized zero forcing beamforming design.

[0191] Embodiment 17. The method of any of embodiments 13 to 16, wherein the self- interference channel coefficients correspond to a center subcarrier of the DL subband.

[0192] Embodiment 18. The method of embodiment 13, wherein a transmit nulling precoder for subcarrier ^^is based on self-interference channel coefficients corresponding to subcarrier ^^where subcarrier ^^depends on a subcarrier ^^, wherein: • if ^^is higher than the DL subband, then ^^is a highest subcarrier in the DL subband; • if ^^is lower than the DL subband, then ^^is a lowest subcarrier in the DL subband; • if ^^is higher than the DL subband, then ^^is set to a subcarrier in a higher half of the DL subband; • if ^^is lower than the DL subband, then ^^is set to a subcarrier in a lower half of the DL subband; • if ^^is higher than the DL subband, then ^^is set to a subcarrier with a fixed frequency separation of ∆^ from ^^; or • if ^^is lower than the DL subband, then ^^is set to a subcarrier with a fixed frequency separation of ∆^ from ^^.

[0193] Embodiment 19. The method of any of embodiments 13 to 18, wherein the transmit nulling precoder comprises a nulling matrix ^ that is constant across a UL subband, and the UL transmission precoder varies across the UL subband.

[0194] Embodiment 20. The method of any of embodiments 13 to 18, wherein the transmit nulling precoder comprises a nulling matrix ^ that is constant across a UL subband, and the UL transmission precoder remains the same across the UL subband.

[0195] Embodiment 21. The method of any of embodiments 13 to 20, wherein the transmit nulling precoder is based on information about transmission side imperfections such as power amplifier non-linearities.

[0196] Embodiment 22. The method of any of embodiments 13 to 21, wherein the transmit nulling precoder is designed based on self-interference channel coefficients corresponding to a UL subband.

[0197] Embodiment 23. A User Equipment device, UE, (1612) for performing transmit nulling to suppress interference in a SubBand Full Duplex, SBFD, transmission, with a network node (1610), the UE (1612) comprising processing circuitry configured to: apply (1502), to a signal, a transmit nulling precoder that is designed based on self-interference channel coefficients corresponding to a downlink, DL, subband; apply (1504), to the signal, an uplink, UL, transmission precoder that is designed based on UL subband channel coefficients; and transmit (1506) the signal to the network node (1610).

[0198] Embodiment 24. The UE (1612) of embodiment 23, wherein the processing circuitry is further configured to perform any of the methods of embodiments 14 to 22.

Claims

CLAIMS 1. A method performed by a network node (1610) for performing transmit nulling to suppress interference in a Full Duplex, FD, transmission, with one or more User Equipments, UEs, (1612) the method comprising: applying (1402), to a signal, a transmit nulling precoder that is designed based on self- interference channel coefficients corresponding to an uplink, UL, subband; applying (1404), to the signal, a downlink, DL, transmission precoder that is designed based on DL subband channel coefficients; and transmitting (1406) the signal to the one or more UEs (1612).

2. The method of claim 1, wherein the DL transmission precoder is determined based on a regularized zero forcing beamforming design.

3. The method of any of claims 1 to 2, wherein the transmit nulling precoder is based on regularized linear projection.

4. The method of claim 1, wherein the DL transmission precoder and the transmit nulling precoder are jointly based on a regularized zero forcing beamforming design.

5. The method of any of claims 1 to 4, wherein the self-interference channel coefficients correspond to a center subcarrier of the UL subband.

6. The method of claim 1, wherein a transmit nulling precoder for subcarrier ^^is based on self-interference channel coefficients corresponding to subcarrier ^^where subcarrier ^^depends on a subcarrier ^^, wherein: • if ^^is higher than the UL subband, then ^^is a highest subcarrier in the UL subband; • if ^^is lower than the UL subband, then ^^is a lowest subcarrier in the UL subband; • if ^^is higher than the UL subband, then ^^is set to a subcarrier in a higher half of the UL subband; • if ^^is lower than the UL subband, then ^^is set to a subcarrier in a lower half of the UL subband; • if ^^is higher than the UL subband, then ^^is set to a subcarrier with a fixed frequency separation of ∆^ from ^^; or • if ^^is lower than the UL subband, then ^^is set to a subcarrier with a fixed frequency separation of ∆^ from ^^.

7. The method of any of claims 1 to 6, wherein the transmit nulling precoder is designed based on self-interference channel coefficients corresponding to a DL subband.

8. The method of any of claims 1 to 7, wherein the transmit nulling precoder comprises a nulling matrix ^ that is constant across the DL subband, and the DL transmission precoder varies across the DL subband.

9. The method of any of claims 1 to 7, wherein the transmit nulling precoder comprises a nulling matrix ^ that is constant across the DL subband, and the DL transmission precoder remains the same across the DL subband.

10. The method of any of claims 1 to 9, wherein the transmit nulling precoder is based on information about transmission side imperfections comprising power amplifier non-linearities.

11. The method of any of claims 1 to 10, wherein self-interference associated with the self- interference channel coefficients is based on at least one of intra-sector interference, inter-sector interference, and inter-site interference.

12. A network node (1610) for performing transmit nulling to suppress interference in a Full Duplex, FD, transmission, with one or more User Equipments, UEs, (1612) the network node (1610) comprising processing circuitry configured to: apply (1402), to a signal, a transmit nulling precoder that is designed based on self- interference channel coefficients corresponding to an uplink, UL, subband; apply (1404), to the signal, a downlink, DL, transmission precoder that is designed based on DL subband channel coefficients; and transmit (1406) the signal to the one or more UEs (1612).

13. The network node (1610) of claim 12, wherein the processing circuitry is further configured to perform any of the methods of claims 2 to 11.

14. A method performed by a User Equipment device, UE, (1612) for performing transmit nulling to suppress interference in a Full Duplex, FD, transmission with a network node (1610), the method comprising:applying (1502), to a signal, a transmit nulling precoder that is designed based on self- interference channel coefficients corresponding to a downlink, DL, subband; applying (1504), to the signal, an uplink, UL, transmission precoder that is designed based on UL subband channel coefficients; and transmitting (1506) the signal to the network node (1610).

15. The method of claim 14, wherein the UL transmission precoder is determined based on a regularized zero forcing beamforming design.

16. The method of any of claims 14 to 15, wherein the transmit nulling precoder is based on regularized linear projection.

17. The method of claim 14, wherein the UL transmission precoder and the transmit nulling precoder are jointly based on a regularized zero forcing beamforming design.

18. The method of any of claims 14 to 17, wherein the self-interference channel coefficients correspond to a center subcarrier of the DL subband.

19. The method of claim 14, wherein a transmit nulling precoder for subcarrier ^^is based on self-interference channel coefficients corresponding to subcarrier ^^where subcarrier ^^depends on a subcarrier ^^, wherein: • if ^^is higher than the DL subband, then^^is a highest subcarrier in the DL subband; • if ^^is lower than the DL subband, then ^^is a lowest subcarrier in the DL subband; • if ^^is higher than the DL subband, then ^^is set to a subcarrier in a higher half of the DL subband; • if ^^is lower than the DL subband, then ^^is set to a subcarrier in a lower half of the DL subband; • if ^^is higher than the DL subband, then ^^is set to a subcarrier with a fixed frequency separation of ∆^ from ^^; or • if ^^is lower than the DL subband, then ^^is set to a subcarrier with a fixed frequency separation of ∆^ from ^^.

20. The method of any of claims 14 to 19, wherein the transmit nulling precoder comprises a nulling matrix ^ that is constant across a UL subband, and the UL transmission precoder varies across the UL subband.

21. The method of any of claims 14 to 19, wherein the transmit nulling precoder comprises a nulling matrix ^ that is constant across a UL subband, and the UL transmission precoder remains the same across the UL subband.

22. The method of any of claims 14 to 21, wherein the transmit nulling precoder is based on information about transmission side imperfections comprising power amplifier non-linearities.

23. The method of any of claims 14 to 22, wherein the transmit nulling precoder is designed based on self-interference channel coefficients corresponding to the UL subband.

24. The method of any of claims 14 to 23, wherein self-interference associated with the self- interference channel coefficients is based on at least one of intra-sector interference, inter-sector interference, and inter-site interference.

25. A User Equipment device, UE, (1612) for performing transmit nulling to suppress interference in a Full Duplex, FD, transmission, with a network node (1610), the UE (1612) comprising processing circuitry configured to: apply (1502), to a signal, a transmit nulling precoder that is designed based on self- interference channel coefficients corresponding to a downlink, DL, subband; apply (1504), to the signal, an uplink, UL, transmission precoder that is designed based on UL subband channel coefficients; and transmit (1506) the signal to the network node (1610).

26. The UE (1612) of claim 25, wherein the processing circuitry is further configured to perform any of the methods of claims 15 to 24.

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