A method to enhance uplink symbol transmission in a wireless network

Abstract

The present invention provides a method for uplink sub-band symbol design in wireless communication systems operating under a Time Division Duplexing (TDD) frame structure. To address interference caused by timing misalignment between uplink and downlink transmissions, the method generates a first uplink symbol with a reduced duration compared to subsequent symbols. User equipment (UE) maps modulated data onto every nth subcarrier using a uniformly spaced subcarrier mapping scheme, creating a sparse frequency-domain representation. This is processed using a standard N-point Inverse Fast Fourier Transform (IFFT), and only the relevant time-domain samples corresponding to the shortened symbol duration are retained. A cyclic prefix of standard length is appended before transmission. The shortened symbol duration is configured through parameters received via the TDD UL-DL configuration. This method eliminates the need to modify the timing advance offset and prevents time wastage due to guard periods, thereby ensuring compatibility with 5G NR and future systems. It improves coexistence, uplink efficiency, and reduces interference.

Description

[0001]A Method to Enhance Uplink Symbol Transmission in a Wireless Network Field of the Invention The present invention relates to wireless communication, particularly to methods and systems for optimizing the frame structure of Time Division Duplex (TDD) systems using Orthogonal Frequency Division Multiplexing (OFDM). It also provides techniques for Sub-Band Full Duplex (SBFD) / Full Duplex (FD) communication to enhance uplink and downlink performance in 5G / 5G-NR and 6G systems. Background of the Invention In 5G NR, Time Division Duplexing (TDD) is widely used in mid-band and high-band spectrum, enabling dynamic allocation of time-domain resources for uplink and downlink over a shared frequency band. To prevent interference between uplink and downlink transmissions a guard period in terms of symbols provided. A guard period, consisting of specific symbols, is incorporated to mitigate interference between uplink and downlink transmissions. The guard period includes timing advance offset (!",#$$%&') which directs the User Equipment (UE) to advance its uplink transmission timing, aligning the signal's arrival at the base station with the designated uplink period. As uplink traffic demand continues to increase, driven by use cases such as extended reality (XR), cloud gaming, and real-time video streaming, Sub-Band Full Duplex (SBFD) operation has been introduced to further improve uplink capacity. SBFD allows simultaneous uplink and downlink transmissions within the same TDD slot by allocating them to different non- overlapping frequency sub-bands. This enables improved spectrum utilization and better support for uplink-heavy applications. SBFD enhances coverage by enabling simultaneous uplink and downlink transmissions in non-contiguous sub-bands, thereby improving spectral efficiency and reducing latency. This allows better utilization of fragmented spectrum and extends reliable communication to cell-edge users. However, introducing SBFD within conventional TDD frame structures presents significant technical challenges, particularly in terms of maintaining timing alignment. In legacy systems, all uplink transmissions will be time advanced by!",#$$%&'. When SBFD is used with this existing timing advance, the first uplink symbol in the SBFD sub-band will overlap with the end of the previous downlink symbol, leading to inter-symbol interference. This degrades uplink signal quality and can significantly impact overall system performance. Current approaches address the issue of overlapping uplink symbol due to!",#$$%&'by omitting the first uplink symbol or by applying distinct timing advances for Sub-Band Full Duplex (SBFD) transmissions, or adjusting the PUSCH mapping and DMRS configurations. However, such methods either reduce uplink throughput, add system complexity or compromise demodulation performance. Accordingly, there exists a need for an improved technique for managing timing offset in SBFD systems that avoids inter-symbol interference without the need for additional guard periods or separate timing configurations. Such a solution should be compatible with existing NR physical layer architecture and support seamless uplink scheduling in TDD- based SBFD systems. Objective of the Invention The principal objective of the present invention is to enable interference-free uplink transmission in Sub-Band Full Duplex (SBFD) communication systems operating under a Time Division Duplex (TDD) framework, without sacrificing the uplink symbols or downlink symbols for timing advance and without changing the 5G NR / OFDM architecture of 6G. Another objective of this invention is to enable a shorter-duration OFDM symbol by reducing the effective duration of the uplink symbol through mapping data to every nth subcarrier and retaining a single copy out of n generated copies, thereby enhancing uplink throughput while mitigating inter-symbol interference between the first uplink symbol in the SBFD sub-band and the preceding downlink symbol. Another objective of the invention is to enable reliable data recovery in the presence of partial symbol interference by transmitting symbols with multiple time-domain copies, generated through mapping to every nth subcarrier. One of the n copies may be used for decoding, thereby enhancing robustness against interference. Another objective of the invention is to enhance the adaptability of the SBFD / Full Duplex system by providing a solution that can dynamically adjust to varying network conditions and symbol configurations. A further objective of the present invention is to enable a shorter OFDM symbol by employing sparse subcarrier mapping in the uplink of TDD frame. Data is mapped to subcarriers with uniform spacing such as every nth subcarrier resulting in a shorter OFDM symbol that can fit in the frame and thereby improving uplink throughput and reducing inter-symbol interference between the initial uplink symbol and the preceding downlink symbol in TDD systems. Summary of the Invention The present invention relates to a method and system for managing uplink timing alignment in 5G New Radio (NR) wireless communication networks operating in Sub-Band Full Duplex (SBFD) mode within a Time Division Duplex (TDD) framework. The invention addresses the technical problem of inter-symbol interference arising from the application of a common timing advance offset (!",#$$%&') to both conventional uplink slots and SBFD uplink sub-bands, result in timing misalignment and overlap between uplink and downlink symbols. In the context of SBFD operation, the invention introduces a novel system architecture and processing mechanism for refining uplink symbol structure to mitigate such interference. The method and system enable precise alignment of the first SBFD uplink symbol with respect to the downlink boundary, thereby preserving the integrity of the TDD frame and ensuring efficient bidirectional communication within the same time slot. A symbol processing system configured to map uplink data onto subcarriers with uniform spacing, wherein data is allocated to every nth subcarrier within the first symbol of the SBFD uplink sub-band. Upon inverse fast Fourier transform (IFFT), this selective subcarrier mapping results in a time-domain waveform containing ‘n’ identical copies. This effectively reduces the useful duration of the uplink symbol while maintaining the same cyclic prefix, allowing the symbol to fit entirely within the time window defined by the existing!",#$$%&'. The system configured to transmit either one or some or all copies of the generated symbol. When all copies are transmitted, the one copy is being time-aligned with the UL region and can be reliably decoded even if the other copies overlap with the downlink symbol. This configuration to transmit smaller first uplink symbol avoids the need to drop uplink symbols, extend guard periods, or introduce dual timing offsets, thereby preserving uplink throughput and minimizing system complexity. The system integrates seamlessly with the existing 5G NR physical layer architecture, including PUSCH mapping, DMRS configuration, cyclic prefix processing, IFFT and FFT engines. By enabling precise timing offset management through alternate subcarrier mapping, the method and system optimize the use of uplink sub-band resources in SBFD operation. By enabling precise timing offset management through uniformly spaced subcarrier mapping, the method and system optimize the use of uplink sub-band resources utilization in SBFD operation. This approach significantly reduces inter-symbol interference, and enhances overall system performance and spectral efficiency. Furthermore, the invention is designed to be fully backward compatible with existing 5G NR deployments and is scalable for adaptation in future 6G systems. The reduction in symbol duration, combined with improved synchronization and interference mitigation, ensures high data integrity, better throughput, and robust performance in evolving SBFD- based wireless networks. Brief description of the drawings The figures described below depict various aspects of the system and methods disclosed herein. It should be understood that each figure depicts an embodiment of a particular aspect of the disclosed system and methods, and that each of the figures is intended to accord with a possible embodiment thereof. Further, wherever possible, the following description refers to the reference numerals included in the following figures, in which features depicted in multiple figures are designated with consistent reference numerals. FIG.1 illustrates the limitations of the current uplink sub-band symbol design within Time Division Duplex (TDD) frame structures in Sub-Band Full Duplex (SBFD) systems (100), highlighting the challenges posed by timing offsets. FIG. 2 depicts the modified uplink sub-band symbol design (200), where the first SBFD uplink symbol has alternate sub-carriers occupied according to one embodiment of the present invention. FIG.3 illustrates a block diagram (300) illustrating the data mapping process to alternate subcarriers in a Sub-Band Full Duplex (SBFD) system according to the exemplary embodiment of the present invention. FIG. 4 provides a block diagram (400) depicting the physical layer processing of PDSCH (Physical Downlink Shared Channel) data in 5G NR according to the exemplary embodiment of the present invention. FIG.5 depicts a block diagram (500) of an uplink sub-band symbol design within Time Division Duplex (TDD) frame structures in Sub-Band Full Duplex (SBFD) systems in a wireless communication system (500), in accordance with one embodiment of the present invention. Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures. Detailed Description of the Invention The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness. The terms and words used in the following description and claims are not limited to the bibliographical meanings but are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces. Figures discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way that would limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged system. The terms used to describe various embodiments are exemplary. It should be understood that these are provided to merely aid the understanding of the description, and that their use and definitions, in no way limit the scope of the invention. Terms first, second, and the like are used to differentiate between objects having the same terminology and are in no way intended to represent a chronological order, unless where explicitly stated otherwise. A set is defined as a non-empty set including at least one element. FIG.1 illustrates the limitations of the current uplink sub-band symbol design within Time Division Duplex (TDD) frame structures in Sub-Band Full Duplex (SBFD) systems (100), highlighting the challenges posed by timing offsets. The issue of timing offset in the Sub-Band Full Duplex (SBFD) frame structure, specifically how it leads to inter-slot interference between uplink (UL) and downlink (DL) transmissions. In traditional Time Division Duplex (TDD) systems, a non-zero Timing Advance Offset (!",#$$%&') is used to provide sufficient time for base station and equipment (UE) to switch from uplink to downlink transmission phases. The value of!",#$$%&'is shown in below table (i.e., Table 7.1.2-2: The Value of!",#$$%&'from TS38.133). Frequency Coexistence Duplex!",#$$%&' !",#$$%&' . *+Range with LTE mode FR1 NO FDD 25600 13 µs TDD YES FDD 0 0 µs TDD 39936 20 µs FR2 NO TDD 13792 7 µs Table 7.1.2-2: The value of!",#$$%&'This offset is applied to uplink transmissions to ensure time alignment by allowing uplink symbols to start slightly earlier, thereby accommodating DL-UL switching within a predefined guard period. However, in sub-band full duplex (SBFD) operation, where simultaneous uplink and downlink occur in separate sub-bands within the same slot, applying the same!",#$$%&'causes the first uplink symbol in the sub-band to begin prematurely before the allocated uplink boundary. As no guard period is reserved in SBFD for this early start, the uplink symbol overlaps with an adjacent downlink symbol, resulting in inter-symbol interference. This overlap is particularly problematic because SBFD assumes concurrent, interference-free operation between UL and DL transmissions. Using different offsets (!",#$$%&') for SBFD and non-SBFD complicates the timing continuity of uplink transmission in UL sub-band and UL slots. This misalignment can lead to performance degradation, including increased interference, reduced throughput or higher latency. Accordingly, there is a need to adapt the symbol structure or manage timing behaviour to prevent interference while maintaining compatibility with existing timing advance configurations, such as those received by a UE via a System Information Block (SIB), and uplink sub-band resource allocation received via RRC or DCI. For example, if the required coverage area of a cell is 4km, then required round trip delay is 26.67μs and 2 symbols need to be reserved as guard symbols. The calculation is given below. *0- / = 2 × 1%'345&6 = 26.679: ≥(26.679: + 209:) ≥ 46.679:; = D !E = 2 symbol duration of a OFDM symbol and is 35.79:. It can be observed that 24.73μs calculated as, 2 x 35.7μs – 46.67μs is effectively wasted, which is significant duration of the OFDM symbol. In this example, it is more than the half the duration of the symbol. FIG. 2 depicts the modified uplink sub-band symbol design (200), where the first SBFD uplink symbol has alternate sub-carriers occupied according to one embodiment of the present invention. The figure presents a time-frequency grid, with the horizontal axis representing the time domain, divided into slots and symbols, and the vertical axis representing the frequency domain, segmented into sub-carriers allocated to the uplink sub- band within the SBFD configuration. The mapping of data to alternate sub-carriers, an Inverse Fast Fourier Transform (IFFT) operation generates two identical copies of the data in the time domain. In one aspect, only one copy of the IFFT-generated data is transmitted over the air, maintaining the cyclic prefix duration equivalent to that of other symbols (6<). The total duration of the first uplink symbol isL%&$LM / 2 +6<, enabling transmission without modification to the existing!",#$$%&', thereby ensuring compatibility with 5G NR timing configurations. FIG.3 illustrates a block diagram (300) for constructing a shortened uplink symbol using alternate subcarrier mapping in a Sub-Band Full Duplex (SBFD) system, in accordance with an exemplary embodiment of the present invention. This method is directed toward mitigating inter-symbol interference caused by applying a standard Timing Advance Offset (!",#$$%&') originally defined for legacy TDD systems to uplink sub-band transmissions in SBFD. The proposed solution enables uplink and downlink coexistence within the same slot without the need to modify timing offset configurations. The proposed method can be extended to mapping onto every nth subcarrier with uniform spacing. In the proposed design, for the first uplink symbol within an SBFD slot, modulated data is mapped to alternate subcarriers in the frequency domain, creating a sparse spectral structure. For example, subcarriers S1, S3, S5 may be populated while subcarriers S2, S4, S6 are left unoccupied. This spectral sparsity yields a symmetric pattern, which, when processed through an N-point Inverse Fast Fourier Transform (IFFT), results in a time-domain signal comprising two identical halves. Two transmission methods are proposed for utilizing the IFFT output: · Transmit only one copy of the data, keeping the CP duration at L%&$LM⁄ 2 + 6<. This method allows the first symbol to betransmitted without modifying the!",#$$%&'· Transmit both copies of the data. One copy may be affected by interference, but the second copy remains unaffected and ensures data recovery. This method showcases the robustness of the alternate mapping approach. The time-domain uplink signal is mathematically represented as: :(P,Q)(R) = S:̅(P,Q)(R) RQ ≤ Q QM start,M R < Rstart,M + *symb,M / W Here, RQstart,Mdenotes the start time of the Xthuplink symbol, and *Qsymb,M / Wis the reduced duration of the shortened uplink symbol. The signal :̅(P,Q)M(R)s obtained from the IFFT of the frequency-domain data and is as: @gsrizide,,db@sRcBch bsize,b:̅(P,Q) = Y Z(P,Q) ]W^_W[`[ RBac@grid,d@sc ⁄ W ef$_'c@bCP,g ! bcc'start,g e ·Z(P,Q)[,M : modulated data symbol at subcarrier index k, X· subcarrier spacing as defined in 3GPP TS 38.211 Clause 4.2 · kjQ: frequency alignment offset defined as: kQ = _ start,Q + size,Q⁄ 2 e RB − start,Qa size,Qarid,n grid,n ⁄ RB QacQj grid,n grid,n sc _ g + 2 e sc 2 link, and μ0 is the largest subcarrier spacing index used across uplink / downlink / sidelink transmissions. The overall symbol duration, including the cyclic prefix, is calculated as: *Qmb,M = p Q + Qsy u CP,M q*cIn conventional systems, samples is: Q= cQL 2048k.2Whereas for the shortened reduced to: Q= 1 cQL 024k.2The cyclic prefix lengthQ CP,Mon the CP type and the symbol index l, as follows: 512k.2cQ \vR\wx\x yz By employing alternate subcarrier mapping and retaining only half of the IFFT output, the invention effectively shortens the duration of the first uplink symbol while preserving the cyclic prefix. Although it is possible to reduce the cyclic prefix length as well, doing so would require detailed channel knowledge. To maintain simplicity, the cyclic prefix of the shortened OFDM symbol is kept the same as in other symbols. This approach ensures that the symbol complies with SBFD timing constraints without the need for a dedicated guard period or modification of the!",#$$%&'. The proposed method is compatible with existing 5G NR frameworks, including configuration mechanisms such as the System Information Block (SIB), Radio Resource Control (RRC) signalling, and Downlink Control Information (DCI). It overcomes the limitations of prior art, including dual- offset schemes and symbol-dropping approaches (e.g., ULCI DCI or PUSCH Mapping Type-B), which either compromise timing continuity or reduce throughput. FIG. 4 provides a block diagram (400) depicting the physical layer processing of PDSCH (Physical Downlink Shared Channel) data in 5G NR according to the exemplary embodiment of the present invention. The diagrams illustrate a sequential flow of processing steps applied to PUSCH data, commencing with the input of the transport block and culminating in the mapping of data from Virtual Resource Blocks (VRB) to Physical Resource Blocks (PRB) for transmission over the air interface. At step 405, the uplink physical layer processing begins with the attachment of a Cyclic Redundancy Check (CRC) to the transport block. This CRC ensures the integrity of the transmitted data by allowing the receiver to detect any bit-level errors in the received transport block. The transport block, after CRC attachment, is processed for segmentation and channel coding, followed by rate matching and mapping onto physical resources. In accordance with an embodiment of the present invention, the calculation of the Transport Block Size (TBS) is adapted to account for the shortened symbol duration used in Sub-Band Full Duplex (SBFD) uplink transmissions. Particularly, when the first uplink symbol is shortened by half or another fractional duration to avoid inter-symbol interference, the number of valid Resource Elements (REs) available for data transmission is adjusted accordingly in the TBS computation. This adjustment is crucial to ensure consistency in the rate matching and scheduling processes. The TBS determination follows the standard formula: =-^ ⋅ %^^ ⋅ − <-^ <-^-^ %6 %JK -^ 0^-^ − #^In the the parameter %- 6^(number of subcarriers per Resource Block) is scaled down by uniform spacing factor denoted ‘n’. The spacing factor ‘n’ may be derived as the reciprocal of a fractional duration parameter, referred to herein as ‘shortULsymbolDurationRatio’. For instance, if the useful symbol duration ishalved, then ‘n’ is 2 and -^%6 =12 × 1^ 2 = 6 subcarriers are effectively used for TBS calculation in that symbol. This fractional duration may take valuessuch as 1^ 2 , 1^ 3 , 1^ 4 , or 1^ 5 , depending on the extent of symbol shortening.To this adaptation, the ‘shortULsymbolDurationRatio’ parameter may be included as an additional field in the TDD-UL-DL configuration. The existing structure of the TDD pattern, as defined in 3GPP, is as follows: TDD-UL-DL-Pattern:: = SEQUENCE { - dl-UL-TransmissionPeriodicity ENUMERATED {ms0p5, ms0p625, ms1, ms1p25, ms2, ms2p5, ms5, ms10}, - nrofDownlinkSlots INTEGER (0..maxNrofSlots), - nrofDownlinkSymbols INTEGER (0..maxNrofSymbols), nrofUplinkSlots INTEGER (0..maxNrofSlots), nrofUplinkSymbols INTEGER (0..maxNrofSymbols), ... } In addition to the fields specified in the TDD-UL-DL pattern, the configuration is extended with a new field: The extended configuration can define: shortUlSymbolDurationRatio ENUMERATED { 1^ 2 , 1^ 3 , 1^ 4 , 1^ 5} This enables the base station and user equipment to consistently interpret and calculate the effective REs during resource allocation and link adaptation procedures. If the field doesn’t exist, it is assumed that there is no short symbol. Furthermore, in the first shortened symbol of the SBFD slot, Demodulation Reference Signals (DMRS) may be omitted to preserve REs for data. Consequently,0<^-^-^may be set to zero for that symbol in the RE calculation, further optimizing the data payload capacity. At step 410, LDPC Base Graph Selection is carried out. The appropriate Low-Density Parity-Check (LDPC) graph is selected based on factors such as the size of the transport block and modulation and coding scheme (MCS) used for the uplink transmission. At step 415, code block segmentation and Code Block CRC Attachment are performed. If the transport block is too large, it is segmented into multiple smaller code blocks. A separate CRC is attached to each code block to facilitate independent error detection and correction. At step 420, channel coding is applied to each code block using LDPC encoding. This step introduces redundancy into the data stream to improve error resilience during transmission. At step 425, rate matching is performed to ensure that the number of encoded bits matches the available physical layer resources-^. Depending on the code rate, this step may include repetition or puncturing and shortening of encoded bits. For short symbol durations, the rate matching specifically considers-^based on the actual subcarrier mapping granularity such as 1 / 2, 1 / 3, 1 / 4, or 1 / 5 subcarrier spacing as indicated by RRC signalling to ensure proper alignment with the available physical layer resources. At step 430, code block concatenation is executed, wherein the individually encoded and rate-matched code blocks are concatenated to form a single bitstream for further processing. At step 435, scrambling is applied to the concatenated bitstream. This randomizes the sequence of bits to reduce the peak-to-average power ratio (PAPR) and to ensure a uniform spectrum. At step 440, modulation is performed, where the scrambled bits are mapped to complex modulation symbols according to the selected modulation scheme, such as QPSK, 16-QAM, 64-QAM, or 256-QAM At step 445, layer and antenna port mapping is applied. The modulation symbols are mapped onto multiple layers and assigned to corresponding antenna ports to support MIMO (Multiple Input Multiple Output) transmission. At step 450, layer-mapped symbols are assigned to virtual resource blocks (VRBs), which represent logical time-frequency allocations. This allows flexible scheduling, independent of physical frequency positions, while respecting constraints such as exclusion zones for reference and synchronization signals. At step 455, VRB-to-PRB (Physical Resource Block) mapping is performed. VRBs are mapped to actual PRB positions using either interleaved or non-interleaved modes. Interleaved mapping offers better frequency diversity, while non-interleaved mapping preserves a contiguous structure. This determines the time-frequency locations for transmitting modulated symbols on the PUSCH, including for the first uplink symbol. Accordingly, FIG.4 provides a detailed view of the physical layer data processing path for uplink PUSCH transmissions, from transport block formation through to final resource allocation. The described steps are compliant with 3GPP 5G NR specifications and support extension for advanced features such as alternate sub-carrier mapping in SBFD, time- aligned symbol shortening, or reference signal optimization. In the context of SBFD uplink transmission employing shortened symbols, the mapping from Virtual Resource Blocks (VRBs) to Physical Resource Blocks (PRBs) incorporates subcarrier allocation based on a uniform spacing factor ‘n’. For shortened uplink symbols, the rate matching operation determines-^based on the effective subcarrier usage ‘n’ which can be obtained by taking reciprocal of ‘shortULsymbolDurationRatio’ signalled via RRC messaging. The RRC messaging, ensuring both the base station and UE apply consistent RE calculation logic for accurate rate matching and modulation. This dynamic adaptation preserves the integrity and efficiency of uplink transmissions in SBFD systems. The existing setup provides several methods to address the issue, though each involves the sacrifice of the first uplink symbol in the sub-band. One method is to send a ULCI DCI message to cancel the transmission of the first uplink symbol. While this approach helps manage timing offsets, it results in the loss of one uplink sub-band symbol for every SBFD time periodicity. This loss decreases the available capacity for uplink transmissions and reduces overall throughput. This may include receiving an Uplink Cancellation Indication (ULCI) Downlink Control Information (DCI) message from a base station, cancelling the transmission of a first uplink symbol in an uplink sub-band in response to the ULCI DCI message to prevent interference with downlink signals, monitoring signal quality metrics following cancellation of the first uplink symbol, and transmitting a response to the base station including the monitored signal quality metrics, wherein monitoring signal quality metrics includes measuring signal strength differences to assess interference reduction. FIG.5 illustrates a system-level block diagram (500) of an uplink and downlink transmission system architecture in a wireless communication network, configured for Sub-Band Full Duplex (SBFD) operation within a Time Division Duplex (TDD) frame structure, in accordance with one embodiment of the present invention. The system is adapted to support transmission of a shortened uplink symbol in the initial symbol position of an SBFD sub-band, thereby enabling uplink and downlink coexistence without requiring modification of timing advance parameters or insertion of additional guard intervals. In one embodiment, a User Equipment (UE) (505) comprises a series of functional modules for uplink physical layer processing. The UE includes an uplink (UL) data processing module (510) configured to receive configuration information such as uplink resource allocation and symbol duration settings via Radio Resource Control (RRC) signalling or Downlink Control Information (DCI). The UL data processing module (510) performs standard operations including cyclic redundancy check (CRC) attachment, low-density parity-check (LDPC) channel coding, rate matching, and modulation, and maps the processed data onto Virtual Resource Blocks (VRBs). The UE further includes an alternative symbol mapping processor (515) operable to convert the VRB-mapped data into a physical-layer representation by mapping the modulated symbols to alternate subcarriers within each Physical Resource Block (PRB). In the mapped structure, every second subcarrier is populated, leaving the intervening subcarriers unoccupied, resulting in spectral sparsity. This sparse frequency-domain configuration introduces symmetry in the resulting time-domain signal after transformation. A time-domain signal generator (520) comprising a standard-length N-point Inverse Fast Fourier Transform (IFFT) engine is configured to perform the IFFT operation and selectively retain only the first N / 2 time- domain samples from the output, corresponding to a single valid copy of the transformed signa. The remaining redundant samples are discarded, and the retained portion constitutes a shortened uplink symbol. A cyclic prefix (CP) of standard length is appended to the shortened symbol to maintain compliance with existing uplink symbol timing in 5G NR TDD systems. An RF signal transmitter (525) is configured to transmit the shortened uplink symbol over the air interface using conventional radio frequency hardware components, including up-conversion circuitry, amplifiers, and synchronization mechanisms. The transmitter may be configured to transmit either one or both of the symmetric copies generated in the IFFT output, depending on predicted downlink interference conditions. At the receiving end, a base station (gNodeB) (530) comprises a UL signal receiver and decoding module (535) configured to receive and synchronize the shortened uplink symbol. Upon reception, the cyclic prefix is removed, and the N / 2-length useful symbol is reconstructed into a full- length N-point time-domain signal through duplication, thereby enabling reuse of a standard-length Fast Fourier Transform (FFT) engine (540) without any hardware modification. The FFT module (540) transforms the reconstructed time-domain symbol into the frequency domain. An extraction module (545) is then employed to extract data only from the alternate subcarriers, ignoring the unused subcarrier positions. In embodiments where both symmetric halves are transmitted, the receiver may identify and utilize the interference-free copy for subsequent decoding, thereby enhancing robustness to downlink / uplink collisions. The base station further includes an SBFD frame setup and control module (550) that is responsible for managing timing advance offsets, SBFD slot formatting, and uplink-downlink switching. This module ensures that the reduced-duration first uplink symbol is aligned within the predefined timing window, avoiding overlap with adjacent downlink transmissions and eliminating the need for guard periods or symbol blanking. A downlink (DL) signal transmission module (555) handles downlink scheduling, beamforming configuration, and the management of reference signals, such as DMRS and CSI-RS, in accordance with the SBFD slot structure. In one embodiment, the mapping of data to subcarriers with uniform spacing wherein data is allocated to every nth subcarrier may be extended to Time Division Duplexing (TDD) uplink-downlink (UL-DL) frame configurations. The parameter ‘shortULsymbolDurationRatio’, signalled via the Radio Resource Control (RRC) message, may be used to indicate the fractional duration of the first uplink symbol within the first uplink slot. This parameter may assume values such as 1 / 2, 1 / 3, 1 / 4, or 1 / 5, and is communicated to the User Equipment (UE) through RRC message. This configuration enables both the transmitter and receiver to determine subcarrier occupancy and the effective symbol duration, thereby facilitating accurate transport block size (TBS) calculation, rate matching, and symbol reconstruction. A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.

Claims

We Claim: for mitigating interference between uplink and downlink transmissions in wireless communication supporting concurrent bidirectional communication, the method comprising: receiving, by a user equipment (UE), configuration information from a base station, the configuration information comprising a sub-band-specific frame structure, a timing advance offset for uplink transmissions, and a symbol duration parameter indicative of a shortened duration for a first uplink symbol; generating, by the UE, the first uplink symbol having a symbol duration shorter than one or more subsequent uplink symbols in a same sub-band, the shortened symbol duration determined based on the symbol duration parameter; mapping, by the UE, modulated symbols to every nth subcarrier of which are uniformly spaced to form a sparse subcarrier structure, wherein the value of n is obtained by taking reciprocal of the symbol duration parameter; performing an inverse fast Fourier transform (IFFT) on the mapped symbols and retaining a portion of the IFFT output samples corresponding to the shortened symbol duration; appending a cyclic prefix to the retained portion of the IFFT output to form a transmit-ready uplink symbol; andtransmitting, by the UE, the first uplink symbol to the base station within a time interval aligned with the timing advance offset.

2. The method as claimed in claim 1, wherein the inverse fast Fourier transform (IFFT) is performed using a standard N-point IFFT engine configured for generating uplink symbols, and wherein a portion of the IFFT output corresponding to a single copy derived based on the reciprocal of the shortened symbol duration factor is retained, and a cyclic prefix of standard length is appended to the retained portion to form a transmit-ready uplink symbol.

3. The method as claimed in claim 1, further comprising computing a transport block size (TBS) for the first uplink symbol based on a number of resource elements-^, wherein the number of subcarriers per resource block (%-5^) is determined by multiplying a standard value of 12 with a shortening factor corresponding to the fractional duration of the first uplink symbol relative to a standard symbol duration.

4. The method as claimed in claim 1, wherein the shortened uplink symbol is transmitted by the user equipment using a timing advance offset that is also applicable to standard uplink symbols of TDD frame configuration, thereby maintaining temporal alignment within the TDD frame.

5. The method as claimed in claim 1, wherein the shortened uplink symbol is allocated within a residual time interval between a downlink symbol and a standard-length uplink symbol in a TDD frame, thereby increasing uplink resource utilization.

6. The method as claimed in claim 1, wherein the shortened uplink symbol enables scheduling of multiple user equipment with different symbol durations within a single TDD uplink slot.

7. A method performed by a base station for mitigating interference between uplink and downlink transmissions in a wireless communication system supporting concurrent bidirectional communication, the method comprising: determining configuration information for a user equipment (UE), the configuration information comprising: a sub-band-specific frame structure; a timing advance offset for uplink transmissions; and a symbol duration parameter indicative of a shortened duration for a first uplink symbol; transmitting the configuration information to the UE; receiving, from the UE, a first uplink symbol generated based on a sparse subcarrier mapping and the shortened symbol duration aligned with the timing advance offset; andprocessing the received symbol based on the subcarrier spacing associated with the shortened symbol duration to extract and recover the transmitted data.

8. A wireless communication system for mitigating interference between uplink and downlink transmissions in a wireless communication network supporting concurrent bidirectional communication, a base station provides configuration information to a user equipment (UE), the configuration information includes a frame structure, a timing advance offset for uplink transmissions, and a symbol duration parameter indicative of a shortened duration for an uplink symbol; the UE generates the uplink symbol based on the symbol duration parameter and a sparse subcarrier mapping, and transmits the uplink symbol to the base station within a time interval aligned with the timing advance offset; and the base station receives the uplink symbol and processes the symbol based on the sparse subcarrier mapping and the symbol duration parameter to recover transmitted data.

9. The wireless communication system as claimed in claim 8, further comprising: the user equipment maps modulated symbols onto every nth subcarrier within a physical resource block (PRB), where n is determined as the reciprocal of the symbol duration parameter;performs a standard N-point inverse fast Fourier transform (IFFT) on the mapped subcarriers and retains a portion of the IFFT output corresponding to the shortened symbol duration; appends a cyclic prefix of standard length to the retained portion to form a transmit-ready uplink symbol; and transmits the symbol to the base station using the timing advance offset.

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