A method for CLI handling in sub-band full duplex based on zero-padded (ZP)-ofdm

Abstract

A METHOD FOR CLI HANDLING IN SUB-BAND FULL DUPLEX BASED ON ZERO- PADDED (ZP)-OFDM The invention relates to a communication method. More particularly, this invention relates to a new duplexing method in cellular systems where uplink (UL) and downlink (DL) user equipment (UE)s are multiplexed on different sub-carriers within the same orthogonal frequency-division multiplexing (OFDM) symbol.

Description

[0001] DESCRIPTION

[0002] A METHOD FOR CLI HANDLING IN SUB-BAND FULL DUPLEX BASED ON ZERO- PADDED (ZP)-OFDM

[0003] TECHNICAL FIELD

[0004] The present invention relates to a wireless communication system and a method for communication therewith. More particularly, this invention relates to a new duplexing method in cellular systems where uplink (UL) and downlink (DL) user equipment (UE)s are multiplexed on different sub-carriers within the same orthogonal frequency-division multiplexing (OFDM) symbol.

[0005] PRIOR ART

[0006] In telecommunications, Cross-Link Interference (CLI) is a type of interference that occurs when communication signals are transmitted between different links, such as those in satellite systems or between base stations in cellular networks, overlapping or interfering with each other. This is particularly relevant in sub-band full-duplex communication systems, where simultaneous transmission and reception of signals occur within the same frequency band. In these systems, CLI can significantly degrade the quality of the communication by causing unintended signal overlap between transmit and receive paths. Effective management of CLI in sub-band full-duplex systems is crucial, as it ensures efficient frequency spectrum utilization and maintains the integrity of communication links, especially in densely populated networks or satellite constellations.

[0007] Several prior works have examined Cross Link Interference (CLI) issues in Sub-band full-duplex (SBFD). One approach relies on SIC (Self-lnterference-Cancellation) in analogue or digital to compensate for the leakage caused by Timing Misalignment (TM) or frequency offset [1]. Many others used neural networks and Deep Learning [2], However, these approaches can only work for Self-Interference (SI) mitigation at the next Generation Node B (gNB) side and are not applicable for inter-UE(User Equipment) CLI.

[0008] TM in UL at the gNB is handled through the use of Timing Advance (TA), and some approaches attempt this kind of alternative [3]. However, this requires an accurate range of information of UEs from gNB and cannot be employed for each UE.

[0009] Other techniques use the measurements of CLI among UEs then schedule them accordingly. Based on the measurement, each pair of aggressor-UE (agg-UE) and victim-UE (vic-UE) are scheduled in different SBFD slots [4], However, the drawback of this is that measurements themselves require timing alignment. To achieve this, some methods focus on enhancing UE-to-UE CLI measurement and reporting [8]. Such methods include coordinated scheduling based on layer 3 (L3) or layer 1 (L1) UE-UE CLI measurement [5] or intra-cell coordinated scheduling [6]. However, these require a lot of overhead and come with huge latency.

[0010] Various methods for UE-to-UE CLI measurement have been proposed in prior art. In the state of the art;

[0011] Some methods that are necessary to investigate specification impacts for timing alignment issues for UE-to-UE CLI measurement and reporting (e.g., timing synchronization between victim UE and aggressor UE for Cross Link Interference-Reference Signal Received Rover (CLI-RSRP) measurement, victim UE’s two different reception timings for CLI-RS (reference signal) and DL). On the other hand, in some methods that support signaling and information exchange for assisting the victim UE with SRS (sounding reference signal) reception timing and / or indicating to the aggressor UE the SRS transmission timing. In another prior art method identifier (ID) coordinated scheduling. It is a heavily discussed issue in literature. But victim and aggressor UEs are not allocated the same time slot in this method.

[0012] The above methods mainly tackle the problem by measuring CLI, which in turn requires timing alignment (closed loop). Even if alignment is assumed, they still introduce a lot of overhead (signaling / latency that contradicts the motivation of SBFD). If this is the case, there are already better alternatives, such as Time-Division Duplexing (TDD).

[0013] Existing methods either struggle to scale effectively in dense network environments or fail to meet the stringent latency and efficiency requirements of next generation networks. Thus, there is a need for novel solutions that can address CLI and TM simultaneously while ensuring scalability, low overhead, and real-time applicability.

[0014] The primary technical challenges / problems in the prior art are;

[0015] • An overhead is needed.

[0016] • The timing misalignment is the show blocker of SBFD is not solved,

[0017] • T raditional SIC methods cannot be used for Inter-UE CLI.

[0018] Sub-band full-duplex (SBFD) communication has emerged as a promising paradigm for enhancing spectral efficiency in modern wireless networks by enabling simultaneous uplink (UL) and downlink (DL) transmissions within the same frequency band. However, when timing misalignment (TM) between UL and DL orthogonal frequency-division multiplexing (OFDM) signals exceed the cyclic prefix (CP) duration, UL sub-carriers from user equipment (UE) leak into the DL sub-carriers, resulting in substantial cross-link interference (CLI). This poses significant hurdles to the practical implementation of SBFD given that TM between the UL and DL frames is inevitable.

[0019] In a conventional SBFD slot where cyclic prefix-orthogonal frequency division multiplexing (CP-OFDM) is used, UL and DL signals are assigned different sub-carriers in the same OFDM symbols within the same time slot. A victim UE (vic-UE) receiving DL from the BS (Base Station) also receives the UL signal from an aggressor UE (agg-UE) with some Timing Misalignment (TM) which will destroy the orthogonality at the symbol level leading to high interference issues.

[0020] The design of techniques for inter-UE CLI handling in SBFD is well-aligned with the current 3GPP standardization efforts, particularly those outlined in Release 18 and subsequent studies focusing on Evolution of NR Duplex Operation. According to 3GPP specifications, full-duplex (FD) technology would be a key enabler in 6G and beyond. SBFD leverages the benefits of FD to reduce latency and improve coverage while lowering the requirements on interference mitigation [7], Furthermore, SBFD improves UL coverage by allowing continuous UL transmission from UEs. As 3GPP's studies on 6G emphasize ultra-low latency and coverage enhancement, SBFD becomes increasingly indispensable. For these reasons, CLI mitigation in SBFD is of utmost importance in 3GPP studies.

[0021] All the problems and limitations mentioned above have made it necessary to make an innovation in the relevant technical field as a result.

[0022] BRIEF DESCRIPTION OF THE INVENTION

[0023] The present invention relates to a method to eliminate the above-mentioned disadvantages and bring new advantages to the relevant technical field.

[0024] The invention relates to a method for UE-to-UE (also known as inter-UE) Cross Link Interference (CLI) mitigation in Sub-Band Full Duplex (SBFD) based on block processing of Zero-Padded Orthogonal Frequency Division Multiplexing modulation (ZP-OFDM).

[0025] The invention basically proposes a method that provides a solution to the issue of the destroyed orthogonality at the symbol level leading to high interference issues when victim UE (vic-UE) receiving DL from the BS also receives the UL signal from an aggressor UE (agg-UE) with some Timing Misalignment (TM).

[0026] To enable Cross Link Interference (CLI) mitigation schemes, network coordination can be required. Next Generation Node Bs (gNBs) can coordinate or exchange information on victim and aggressor devices. The information can include the following:

[0027] • UE's measurement reports

[0028] • Identified aggressor and / or victim UEs

[0029] • Identified aggressor and / or victim beams.

[0030] UE’s can be mobile phone, smartphones, tablets, modems (mobile Wi-Fi routers), smartwatches with SIM card connectivity, loT devices (like vehicle tracking systems and smart home sensors), and laptops with eSIM or SIM card support, etc.

[0031] A victim device can be a UE or gNB, and an aggressor device can be a UE or gNB. Unlike traditional methods which avoid severe CLI based on reported measurements, this method tries to undo this interference without rescheduling, thereby reducing the latency. Moreover, this method can be used to improve CLI measurement, as Timing Misalignment (TM) plays a huge role in measurement accuracy.

[0032] This method can also be applied for Self-Interference (SI) at gNB, but traditional SIC methods cannot be used for Inter-UE CLI. CLI measurement is used in this invention. Based on the measured CLI reschedule UEs.

[0033] Furthermore, proposed method in the invention that can be used instead of Timing Advance (TA), at the gNB, thereby reducing a lot of the overhead associated with it.

[0034] An object of the invention is to provide

[0035] • To mitigate Cross-Link Interference (CLI) in Sub-Band Full Duplex (SBFD) systems, particularly under Timing Misalignment (TM) between uplink (UL) and downlink (DL) signals that destroy sub-carrier orthogonality.

[0036] • To enable CLI handling at the victim User Equipment (vic-UE) level, eliminating the need for timing alignment and measurement overhead.

[0037] • To provide a method that is backward compatible, requiring no change to the physical layer (PHY) of legacy systems, since it builds upon OFDM-based waveforms. • To reduce latency and improve spectral efficiency and to support flexible implementation.

[0038] In the proposed scheme, the UE can still separate the two signals by processing the entire slot or sub-slots. A slot is defined as a number of consecutive OFDM symbols, during which the UE either transmits UL or receives DL from the BS. E.g., in 5G systems, it is defined as 14 OFDM symbols. The two signals will be orthogonal in the frequency domain, with some linear phase shift in the interfering signal that is related to the timing misalignment (TM).

[0039] The disclosed invention leverages two distinct OFDM prefix schemes to implement On-Off Keying (OOK) modulation inherently. This approach offers several notable advantages:

[0040] • Spectral Efficiency: by reducing the overhead associated with the CLI measurement and scheduling. Reducing the latency.

[0041] • Power Efficiency: Minimizing the power wasted in the CLI measurement and reporting. Plus, the power is saved through the use of ZP-OFDM as compared to CP-OFDM.

[0042] • High Performance: Even if the method would only be used for CLI measurement not mitigation, it is still highly advantageous, because of the huge role TM plays in CLI measurement. This method can be used to obtain more accurate measurements.

[0043] • Backward Compatibility: The invention introduces no major changes to the physical layer (PHY) since it is OFDM based, ensuring compatibility with existing systems. This facilitates easier integration and deployment without requiring significant modifications to current infrastructure.

[0044] By means of the present invention;

[0045] • No overhead is needed.

[0046] • The undesired signal is suppressed.

[0047] • By going back to the time domain, the symbols in the desired slot will be shifted back to their respective indices.

[0048] • Using the linear phase in the frequency domain.

[0049] • There is no need to assume known misalignment.

[0050] • There is no need to measure CLI.

[0051] A possible embodiment of the invention is that the slots are divided into multiple sub-slots separated by guard durations.

[0052] Another possible embodiment of the invention is characterized in that;

[0053] • The guard duration is determined by cell radius and UL transmission powers of UEs. • UEs are always using ZP-OFDM in Sub-band full-duplex slot as preventative measure.

[0054] • Decision taken by the gNB for UEs to use Zero-Padded (ZP)- orthogonal frequencydivision multiplexing in SBFD based on Cross-Link Interference measurement.

[0055] • Using Zero-Padded (ZP)-OFDM in SBFD only for Cross-Link Interference measurement.

[0056] • The received signal at the vic-UE without noise is the model for Cross-Link Interference measurement reference signals.

[0057] • The vic-UE processes s[n] in the frequency domain.

[0058] • One aspect of the proposed technique is to measure the exact misalignment through the information contained in the linear phase, assuming a simple channel between vic- UE and agg-UE that can be predicted.

[0059] • A guard band between UL and DL sub-bands. This is traditionally proposed to mitigate Cross-Link Interference. However, when it comes to TM in traditional SBFD systems, it is much less effective. In the proposed method, it has a greater impact.

[0060] • After filtering the UL sub-band, IFFT can be taken, and the UE can process each symbol separately to extract data.

[0061] • One aspect is to use Common-CP- orthogonal frequency-division multiplexing instead of Zero-Padded (ZP)- orthogonal frequency-division multiplexing.

[0062] • Use of different numerologies for UL and DL instead of one, as by processing on predefined sub-slots, orthogonality can still be maintained.

[0063] • Dividing the slot into its constituent ZP-OFDM symbols by taking the FFT at the symbol level for each symbol; equalizing to remove the channel effect, and recovering the data symbols from the DL sub-carriers.

[0064] The proposed invention can be implemented in signal technology for cellular networks (5G, 5G beyond, 6G and beyond), Wi-Fi, loT application etc.

[0065] The proposed method depends on the computer implemented method. The method which can be executed by an apparatus for wireless communication at a base station in a wireless communications system (the apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory), or a network device, or by a component of the network device (such as a processor, a chip, or a chip system, etc.), or can be implemented by all or logical modules or software implementations of some network device functions or computer implemented device. The features and advantages of the embodiments will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which reference characters identify corresponding elements throughout.

[0066] BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The present disclosure, in accordance with one or more various examples, is described in detail with reference to the following figures. The drawings are provided for purposes of illustration only and merely depict examples of the disclosure. These drawings are provided to facilitate the reader's understanding of the disclosure and should not be considered limiting the breadth, scope, or applicability of the disclosure. It should be noted that for clarity and ease of illustration these drawings are not necessarily made to scale.

[0068] Figure 1 : An example of the possible interference scenarios in SBFD.

[0069] Figure 2: An example of how TM makes UL sub-band leak to DL sub-band (Amplitude vs SubCarrier Index) (Ideal Case and TM graphs

[0070] Figure 3: An example of two ZP-OFDM signals arriving with some TM that is larger than the ZP length.

[0071] Figure 4: An example of the oversampled UL signal (Amplitude vs Sub-Carrier Index).

[0072] Figure 5: An arbitrary UL symbol from the slot in the time domain and the result after applying interference cancellation to it (Amplitude vs Time Index).

[0073] Figure 6: An example of implementation of the proposed method.

[0074] REFERENCE NUMBERS GIVEN IN THE FIGURE

[0075] The reference numbers of the elements included in the figures are explained below.

[0076] 1 ZP-OFDM symbols

[0077] 2 Time Misalignment

[0078] 3 DL desired signal

[0079] 4 UL interference signal

[0080] 5 OFDM slot

[0081] 6 Self Interference (SI)

[0082] 7 CLI between gNBs

[0083] 8 CLI between UEs

[0084] 9 ZP OFDM SLOT

[0085] 10 FFT Slot Level 11 Interference Removal (Filtering)

[0086] 12 IFFT Slot Level

[0087] 13 Window Alignment Symbol Level

[0088] 14 FFT Symbol Level

[0089] 15 Frequency Domain Data Processing

[0090] 16 Block Processing for CLI Handling

[0091] DETAILED DESCRIPTION OF THE INVENTION

[0092] In this detailed description, the subject matter is explained with references to examples without forming any restrictive effect only to make the subject more understandable. To achieve all the objectives mentioned above and that will emerge from the following detailed description.

[0093] This invention relates to a new duplexing method in cellular systems where uplink (UL) and downlink (DL) users / user equipment (UE)s are multiplexed on different sub-carriers within the same OFDM symbol. The method is based on block processing of ZP-OFDM. The proposed method comes with the assumption of using ZP-OFDM for SBFD slots.

[0094] Invention proposes the use of zero-padding (ZP)-OFDM waveform for the SBFD slots. The inherent structure of ZP-OFDM allows for block processing of the received frame, enabling effective suppression of inter-UE CLI even in the presence of TM. Thereby eliminating the need for a guard band between the UL and DL sub-bands and significantly enhancing the practicality of SBFD systems.

[0095] Aspects of the present disclosure use ZP-OFDM for SBFD slots and CP (Cyclic Prefix)-OFDM for legacy slots (non-SBFD slots). The disclosure provides methods for ZP-OFDM block processing to combat Timing Misalignment (TM) for CLI handling in SBFD. In the case of timing misalignment smaller than the cyclic prefix length, both the disclosed invention and the conventional ZP-OFDM receiver can be deployed.

[0096] The invention is a computer implemented method for duplexing in cellular systems where uplink (UL) and downlink (DL) users / user equipments (UE)s are multiplexed on different subcarriers within the same OFDM symbol, characterized in that comprising steps of:

[0097] • Starting downlink process in transmitter for transmitting data from a base station (gNB) to at least one device in a wireless communication system, • Checking whether the slots as sub-band full-duplex to pick cyclic prefix orthogonal frequency-division multiplexing or Zero-Padded orthogonal frequency-division multiplexing,

[0098] • If the slot is not a sub-band full-duplex, using conventional cyclic prefix- orthogonal frequency-division multiplexing,

[0099] • If the slot is a sub-band full-duplex, using Zero-Padded- orthogonal frequencydivision multiplexing in transmitter,

[0100] o After using Zero-Padded- orthogonal frequency-division multiplexing in transmitter, measuring timing misalignment by using uplink Cross-Link Interference information to detect and correct timing misalignment in communication networks in the receiver,

[0101] o Checking whether timing misalignment value is bigger than Zero-Padded, o If the timing misalignment value is not bigger than Zero-Padded, using Conventional Zero-Padded- orthogonal frequency-division multiplexing in receiver, o If the timing misalignment value is bigger than Zero Duration, processing whole block (all OFDM symbols)-Fast Fourier transform (FFT) (slot),

[0102] o Cancelling out uplink (UL) sub-carriers to improve the overall efficiency of the network,

[0103] o Applying Inverse Fast Fourier transform (IFFT) to whole block (all OFDM symbols) to convert frequency domain data into time domain signals,

[0104] o Processing symbol by symbol through dividing the slot into its constituent ZP- OFDM symbols which is called conventional Zero-Padded- orthogonal frequencydivision multiplexing in receiver.

[0105] The cancellation of uplink sub-carriers is generally performed for purposes such as better performance, reduced interference, more efficient spectrum utilization, and optimization of network capacity. This process aims to improve the overall efficiency of the network. Cancelling out uplink (UL) sub-carriers process in the method; filtering the UL sub-carriers using a digital band-stop filter, i.e., multiplying them to be zeros.

[0106] Measuring timing misalignment using uplink Cross-Link Interference information to detect and correct timing misalignment in communication networks in the receiver process is critical for improving network performance and reducing signal interference.

[0107] Applying Inverse Fast Fourier transform (IFFT) to whole block to convert frequency domain data into time domain signals used for enabling efficient multicarrier transmission and minimizing intercarrier interference (ICI) in a wireless communication system. Processing symbol by symbol in the method: This involves dividing the slot into its constituent ZP-OFDM symbols; taking the FFT at the symbol level for each symbol; equalizing to remove the channel effect and recovering the data symbols from the DL sub-carriers.

[0108] "Symbol by symbol processing" in conventional Zero-Padded Orthogonal Frequency-Division Multiplexing (ZP-OFDM) is primarily done to improve signal quality, reduce interference, simplify receiver processing, and enhance synchronization in wireless communication systems. By introducing zero padding, the system can achieve better sub-carrier orthogonality, minimize inter-carrier interference (ICI), and make communication more robust in challenging channel conditions. Zero padding helps preserve orthogonality between sub-carriers and reduces overlap between them, which improves overall system performance. Moreover, symbol-by-symbol processing is particularly useful for timing synchronization and channel equalization. When symbols are transmitted in a zero-padded manner, it becomes easier to synchronize the receiver and correct for any timing or frequency errors. This method also simplifies equalization techniques, as the symbols are cleanly separated in time, making it easier to estimate the frequency response of the channel.

[0109] In the method, an aggressor-UE (agg-UE) is transmitting UL signal in a SBFD slot, while a vic-UE is receiving DL from gNB in a SBFD slot, [Figure 1]. The shown scenarios in the figure 1 include inter-UE CLI, inter-BS CLI, and self-interference from the BS on itself.

[0110] The received signal at the vic-UE without noise is modeled as

[0111]

[0112] where T is the TM; it can be positive or negative. stx[n] is the transmitted (sub)slot at the gNB and s'x[n] is the transmitted (sub)slot at the agg-UE.

[0113] As can be seen (right) in figure 2, because of TM, DL and UL sub-bands are no longer orthogonal.

[0114] Traditionally, the misalignment in modelling the received signal at the vic-UE without noise step completely destroys the orthogonality between UL and DL leading to serious CLI levels (Figure 2). This has been identified as the main cause for spectral leakage in SBFD [4], This is different than side lobes residual leakage from filtering for example. This is much more severe and unpredictable. Aspects of the present disclosure include UEs are always using ZP-OFDM in SBFD slot as preventative measure.

[0115] One aspect of the present disclosure includes a decision taken by the gNB for UEs to use ZP-OFDM in SBFD based on CLI measurement. The decision involves choosing between ZP-OFDM or CP-OFDM to use in the SBFD slot. If the reported CLI levels are low enough, the use of conventional OFDM (i.e., symbol level processing) is possible, instead of the block processing introduced by the proposed method. If the CLI level is too high, the gNB decides to use ZP-OFDM with block processing to counter-act the resulting CLI. Here, higher and lower than a predefined level. This level is based on the acceptable SINR (signal-to-interference-plus-noise ratio) condition for proper reception of the UE.

[0116] One aspect of the present disclosure includes using ZP-OFDM in SBFD only for CLI measurement. In this case the signal in modeling the received signal at the vic-UE without noise step is the model for CLI measurement reference signals.

[0117] Aspects of the present disclosure include taking the entire frame in time domain. In which case, the slot consists of M = 14 OFDM symbols.

[0118] One option is to divide the slot into multiple sub-slots separated by guard durations. For example, M = 7 OFDM symbols per sub-slot. Guard duration TGcan be expressed as percentage of N, where N is the OFDM symbol duration (in samples).

[0119] The transmitted signal in time domain can be expressed as

[0120]

[0121] where ZP is the ZP-length. The expression works for the Tx signal at both gNB and agg-UE. The difference is in the sub-carrier indices. For the i-th OFDM symbol,

[0122] x n] = IFFT( Xt [k]) .

[0123] The guard duration determines the maximum TM that can be handled and is chosen based on the expected / measured TM, such that no inter-(sub)slot occurs. For instance, rGis proportional to the cell radius r as rG= A-r, where A is a constant related to the expected maximum TM value, which is related to the other measures taken against TM such as possible coordinated scheduling. The guard duration is determined by using cell radius and UL transmission powers of UEs.

[0124] Unlike CP-OFDM, using ZP OFDM [Figure 3], allows us to expresss[n] as

[0125]

[0126] The signal in the above step (ZP OFDM [Fig 3]) can be further processed in time\frequency, and CLI caused by TM can be mitigated.

[0127] Aspects of the present disclosure include the vic-UE processes s[n] in the frequency domain. vic-UE takes the FFT of the signal in the above step (ZP OFDM [Fig 3]). Each symbol in the time domain will be oversampled to M(ZP + N) + rGsamples with a linear phase shift unique to each symbol and delay. Each DL symbol will occupy the same band, but they are still orthogonal because of the linear phase. Each UL signal occupies the UL band and can be filtered out with minimum interference.

[0128] Choosing TGto satisfy M * ZP + rG= * N for some integer p simplifies the expression for the oversampled sub-carrier to

[0129]

[0130] wheren' is the sub-carrier index, k is time domain OFDM symbol index. This is the same for an UL or DL sub-carrier, with the distinction being the linear phase from the TM. p can be optimized for the desired spectral efficiency and CLI mitigation. For example, [Fig 4] shows what happens to the UL signal, for = panel TG= Cl¬

[0131] one aspect of the proposed technique is to measure the exact misalignment through the information contained in the linear phase, assuming a simple channel between vic-UE and agg-UE that can be predicted. For example, with dominant Line-of-Sight (LOS) component or available CSI between the UEs.

[0132] Aspects of the present disclosure include using a guard band between UL and DL sub-bands. This is traditionally proposed to mitigate CLI. However, when it comes to TM in traditional SBFD systems, it is much less effective. In the proposed method, it has a greater impact, as the CLI becomes more predictable. The resulting interference is critically reduced (compare the amount of leakage in [Figure 2] and [Figure 4]).

[0133] After filtering the UL sub-band, IFFT can be taken, and the UE can process each symbol separately to extract data. Interference is minimized [Figure 5].

[0134] One aspect is to use this approach at gNB. If each UE transmits UL signals at the same time, signals from different UEs arrive at different times because they lie at different ranges. For that, Timing Advance (TA) is usually used, which requires huge overhead and accurate time of arrival knowledge. Using the proposed block processing of ZP OFDM, different arrival times can be tolerated, and overhead is avoided.

[0135] One aspect is to use Common-CP-OFDM instead of ZP-OFDM. This method also includes the use of different numerologies for UL and DL instead of one, as by processing on predefined sub-slots, orthogonality can still be maintained.

[0136] In figure 6, an example of implementation of the proposed method as a block diagram is shown. These are; Using ZP OFDM Slots (9) (Desired + interference ZP-OFDM signals, with Time Misalignment on the interference signal), Fast Fourier Transforming of slot levels (It is in processing for CLI handling), Filtering of interference (It is in processing for CLI handling), Inverse Fast Fourier transform of slot levels (It is in processing for CLI handling), Windowing alignment symbol level (13), Fast Fourier Transforming of slot levels, Data processing is in frequency domain.

[0137] The scope of protection of the invention is specified in the attached claims and cannot be limited to those explained for sampling purposes in this detailed description. It is evident that a person skilled in the art may exhibit similar embodiments in light of the above-mentioned facts without drifting apart from the main theme of the invention. REFERENCES

[0138] [1] Lee, H., Choi, J., Kim, D., & Hong, D. (2017, March). Impact of time and frequency misalignments in OFDM based in-band full-duplex systems. In 2017 IEEE Wireless Communications and Networking Conference (WCNC) (pp. 1-6). IEEE.

[0139] [2] Kurzo, Y., Burg, A., & Balatsoukas-Stimming, A. (2018, October). Design and implementation of a neural network aided self-interference cancellation scheme for full-duplex radios. In 2018 52nd Asilomar Conference on Signals, Systems, and Computers (pp. 589-593). IEEE.

[0140] [3] Carrillo, D., Neto, G. G., Sakai, S. M., Souza, W. L., Caldeira, R. T., & Bazzo, J. J. (2016, November). A low-cost test platform to estimate the LTE timing advance procedure. In 2016 8th IEEE Latin-American Conference on Communications (LATINCOM) (pp. 1-6). IEEE.

[0141] [4] 38858-i10; Study on Evolution of NR Duplex Operation

[0142] [5] R1 -2308336, Discussion on evaluation and methodologies on evolution of NR duplex operation, Huawei, HiSilicon.

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[0144] [7] Abdelghaffar, M., Santhappan, T. V. P., Tokgoz, Y., Mukkavilli, K., & Ji, T. (2024). Subband full-duplex large-scale deployed network designs and tradeoffs. Proceedings of the IEEE.

[0145] [8] W02020146891 A1 : UE to UE Crosslink Interference Measurement and Reporting.

Claims

CLAIMS1. A computer implemented method for duplexing in cellular systems where uplink (UL) and downlink (DL) user equipments (UE)s are multiplexed on different sub-carriers within the same orthogonal frequency-division multiplexing (OFDM) symbol, characterized in that comprising steps of:• Starting downlink process in transmitter for transmitting data from a base station (gNB) to at least one device in a wireless communication system,• Checking whether a slot is sub-band full-duplex or not,• If the slot is not a sub-band full-duplex, using conventional cyclic prefix (CP)- orthogonal frequency-division multiplexing,• If the slot is a sub-band full-duplex, using zero-padded orthogonal frequency-division multiplexing (ZP-OFDM) in transmitter,o After using Zero-Padded orthogonal frequency-division multiplexing in transmitter, measuring timing misalignment by using uplink Cross-Link Interference information to detect and correct timing misalignment in communication networks in the receiver,o Checking whether timing misalignment value is bigger than Zero-Padded (ZP), o If the timing misalignment value is not bigger than Zero-Padded, using Conventional Zero-Padded- orthogonal frequency-division multiplexing in receiver,o If the timing misalignment value is bigger than ZP duration, processing all OFDM symbols by using Fast Fourier transform (FFT),o Cancelling out uplink (UL) sub-carriers to improve the overall efficiency of the network,o Applying Inverse Fast Fourier transform (IFFT) to all OFDM symbols to convert frequency domain data into time domain signals,o Processing symbol by symbol through dividing the slot into its constituent ZP- OFDM symbols which is called conventional Zero-Padded- orthogonal frequency-division multiplexing in receiver.

2. The method according to claim 1 , is characterized in that Zero-Padded (ZP)-OFDM in SBFD is used only for Cross-Link Interference measurement.

3. The method according to claim 1, is characterized in that measuring the exact misalignment is through the information contained in the linear phase.

4. The method according to claim 1, is characterized in that dividing the slot into its constituent ZP-OFDM symbols by taking the Fast Fourier transform (FFT) at the symbollevel for each symbol; equalizing to remove the channel effect, and recovering the data symbols from the DL sub-carriers.

5. The method according to claim 1 , is characterized in that the slots are divided into multiple sub-slots separated by guard durations.

6. The method according to claim 5, is characterized in that said the guard duration is determined by using cell radius and UL transmission powers of UEs.

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