System and method for transmitting a demodulation reference signal (DMRS) sequence to user equipment

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. A method (800) performed by an open radio access network (O-RAN) radio unit (O-RU) for transmitting a demodulation reference signal (DMRS) sequence to a user equipment (UE)(612) is disclosed. The method (800) includes receiving (802)(608), a reduced parameter set associated with DMRS configuration from an O-RAN-distributed unit (O-DU)(606). Upon receiving the reduced parameter set, generating (804) a randomized bit stream. The method includes determining (806) the DMRS sequence　using the generated randomized bit stream. The method includes transmitting (808) the determined DMRS sequence over one or more resource elements (REs)(610a, 610b, 610c,..., 610n) in a frequency domain to a user equipment (UE)(612) using the reduced parameter set.

Description

SYSTEM AND METHOD FOR TRANSMITTING A DEMODULATION REFERENCE SIGNAL (DMRS) SEQUENCE TO USER EQUIPMENT

[0001] The present disclosure generally relates to wireless communication. More particularly, the present disclosure relates to a method and a system for transmitting a Demodulation Reference Signal (DMRS) Sequence to a User Equipment (UE).

[0002] Considering the development of wireless communication from generation to generation, the technologies have been developed mainly for services targeting humans, such as voice calls, multimedia services, and data services. Following the commercialization of 5G (5th-generation) communication systems, it is expected that the number of connected devices will exponentially grow. Increasingly, these will be connected to communication networks. Examples of connected things may include vehicles, robots, drones, home appliances, displays, smart sensors connected to various infrastructures, construction machines, and factory equipment. Mobile devices are expected to evolve in various form-factors, such as augmented reality glasses, virtual reality headsets, and hologram devices. In order to provide various services by connecting hundreds of billions of devices and things in the 6G (6th-generation) era, there have been ongoing efforts to develop improved 6G communication systems. For these reasons, 6G communication systems are referred to as beyond-5G systems.

[0003] 6G communication systems, which are expected to be commercialized around 2030, will have a peak data rate of tera (1,000 giga)-level bps and a radio latency less than 100μsec, and thus will be 50 times as fast as 5G communication systems and have the 1 / 10 radio latency thereof.

[0004] In order to accomplish such a high data rate and an ultra-low latency, it has been considered to implement 6G communication systems in a terahertz band (for example, 95GHz to 3THz bands). It is expected that, due to severer path loss and atmospheric absorption in the terahertz bands than those in mmWave bands introduced in 5G, technologies capable of securing the signal transmission distance (that is, coverage) will become more crucial. It is necessary to develop, as major technologies for securing the coverage, radio frequency (RF) elements, antennas, novel waveforms having a better coverage than orthogonal frequency division multiplexing (OFDM), beamforming and massive multiple input multiple output (MIMO), full dimensional MIMO (FD-MIMO), array antennas, and multiantenna transmission technologies such as large-scale antennas. In addition, there has been ongoing discussion on new technologies for improving the coverage of terahertz-band signals, such as metamaterial-based lenses and antennas, orbital angular momentum (OAM), and reconfigurable intelligent surface (RIS).

[0005] Moreover, in order to improve the spectral efficiency and the overall network performances, the following technologies have been developed for 6G communication systems: a full-duplex technology for enabling an uplink transmission and a downlink transmission to simultaneously use the same frequency resource at the same time; a network technology for utilizing satellites, high-altitude platform stations (HAPS), and the like in an integrated manner; an improved network structure for supporting mobile base stations and the like and enabling network operation optimization and automation and the like; a dynamic spectrum sharing technology via collison avoidance based on a prediction of spectrum usage; an use of artificial intelligence (AI) in wireless communication for improvement of overall network operation by utilizing AI from a designing phase for developing 6G and internalizing end-to-end AI support functions; and a next-generation distributed computing technology for overcoming the limit of UE computing ability through reachable super-high-performance communication and computing resources (such as mobile edge computing (MEC), clouds, and the like) over the network. In addition, through designing new protocols to be used in 6G communication systems, developing mecahnisms for implementing a hardware-based security environment and safe use of data, and developing technologies for maintaining privacy, attempts to strengthen the connectivity between devices, optimize the network, promote softwarization of network entities, and increase the openness of wireless communications are continuing.

[0006] It is expected that research and development of 6G communication systems in hyper-connectivity, including person to machine (P2M) as well as machine to machine (M2M), will allow the next hyper-connected experience. Particularly, it is expected that services such as truly immersive extended reality (XR), high-fidelity mobile hologram, and digital replica could be provided through 6G communication systems. In addition, services such as remote surgery for security and reliability enhancement, industrial automation, and emergency response will be provided through the 6G communication system such that the technologies could be applied in various fields such as industry, medical care, automobiles, and home appliances.

[0007] The information in this section merely provides background information related to the present disclosure and may not constitute prior art(s) for the present disclosure.

[0008] In conventional wireless communication systems, Demodulation Reference Signals (DMRS) are transmitted from a base station to a User Equipment (UE) to assist in channel estimation and demodulation of downlink data. DMRS sequences are typically generated at a baseband processing unit within the base station, based on system-defined parameters such as UE-specific Radio Network Temporary Identifier (RNTI), scrambling identity, and time-frequency resource allocation.

[0009] Typically, in a distributed architecture Base Station (BS), a functional split determines the number of functions performed locally at an antenna site O-Radio Access Network (RAN) Radio Unit (O-RU), and the number of functions centralized at a high-processing powered data centre O-RAN Distributed Unit (O-DU). In certain O-RAN implementations, the O-DU performs higher-layer processing, while the O-RU handles lower-layer tasks, including physical layer operations. Some prior solutions involve transmitting full DMRS configuration and sequences from the O-DU to the O-RU over a fronthaul (FH) link, which can result in significant fronthaul bandwidth consumption.

[0010] Existing methods also face challenges in scaling efficiently for massive Multiple Input Multiple Output (MIMO) systems, where per-layer or per-antenna DMRS generation increases complexity and fronthaul overhead. Techniques like IQ compression and beamforming weights application are often utilized to mitigate such overhead, but optimization is still required.

[0011] The present disclosure relates to a method and apparatus for transmitting a demodulation reference signal (DMRS) sequence.

[0012] This solution is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention. This solution is neither intended to identify key or essential inventive concepts of the invention nor is it intended for determining the scope of the invention.

[0013] A method performed by an open radio access network (O-RAN) radio unit (O-RU) for transmitting a demodulation reference signal (DMRS) sequence is disclosed. The method includes receiving a reduced parameter set associated with DMRS configuration from an O-RAN-distributed unit (O-DU). Upon receiving the reduced parameter set, further, the method includes generating a randomized bit stream. The method includes determining the DMRS sequence　using the generated randomized bit stream. The method includes transmitting the determined DMRS sequence over one or more resource elements (RE) in a frequency domain to a user equipment (UE) using the reduced parameter set.

[0014] A system for transmitting a demodulation reference signal (DMRS) sequence is disclosed. The system includes a baseband unit (BBU) having an Open Radio Access Network (O-RAN) centralized unit (O-CU) and an O-RAN distributed unit (O-DU). Further, the system includes an O-RAN Radio Unit (O-RU) remote from the BBU. The O-RU is configured to receive a reduced parameter set associated with DMRS configuration from an O-RAN-Distributed Unit (O-DU). Upon receiving the reduced parameter set, further, the O-RU is configured to generate a randomized bit stream. The O-RU is configured to determine the DMRS sequence　using the generated randomized bit stream. The O-RU is configured to transmit the determined DMRS sequence over one or more resource elements (RE) in a frequency domain to a user equipment (UE) using the reduced parameter set.

[0015] To further clarify the advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.

[0016] According to embodiments of the present disclosure, efficient communication can be achieved.

[0017] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings.

[0018] Figure 1 illustrates a Third Generation Partnership Project (3GPP) having eight functional splits, in accordance with the conventional techniques;

[0019] Figure 2 illustrates a 7.2x split architecture, in accordance with the conventional techniques;

[0020] Figure 3 illustrates a block diagram showing a new functional Split for Extreme-Multiple Input Multiple Output (MIMO) Base Stations (X-MIMO BSs), in accordance with the conventional techniques;

[0021] Figure 4 illustrates a block diagram depicting Downlink (DL) a Demodulation Reference Signal (DMRS) Processing at an Open Radio Access Network (O-RAN) Distributed Unit (O-DU), in accordance with the conventional techniques;

[0022] Figure 5 illustrates a plot between the DMRS Mapping type and the DMRS Configuration Type, in accordance with the conventional techniques;

[0023] Figure 6 illustrates a block diagram depicting an environment for transmitting a Demodulation Reference Signal (DMRS) sequence, in accordance with an embodiment of the present disclosure;

[0024] Figure 7 illustrates a block diagram of a system, in accordance with an embodiment of the present disclosure; and

[0025] Figure 8 illustrates a flowchart depicting an exemplary method for transmitting the DMRS sequence to the UE, in accordance with an embodiment of the present disclosure.

[0026] Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have necessarily been drawn to scale.

[0027] Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

[0028] For the purpose of promoting an understanding of the principles of the present disclosure, reference will now be made to the various embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the present disclosure is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the present disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the present disclosure relates.

[0029] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are explanatory of the present disclosure and are not intended to be restrictive thereof.

[0030] Whether or not a certain feature or element was limited to being used only once, it may still be referred to as "one or more features" or "one or more elements" or "at least one feature" or "at least one element." Furthermore, the use of the terms "one or more" or "at least one" feature or element does not preclude there being none of that feature or element, unless otherwise specified by limiting language including, but not limited to, "there needs to be one or more..." or "one or more elements is required."

[0031] Reference is made herein to some "embodiments." It should be understood that an embodiment is an example of a possible implementation of any features and / or elements of the present disclosure. Some embodiments have been described for the purpose of explaining one or more of the potential ways in which the specific features and / or elements of the proposed disclosure fulfil the requirements of uniqueness, utility, and non-obviousness.

[0032] Use of the phrases and / or terms including, but not limited to, “a first embodiment,” “a further embodiment,” “an alternate embodiment,” “one embodiment,” “an embodiment,” “multiple embodiments,” “some embodiments,” “other embodiments,” “further embodiment”, “furthermore embodiment”, “additional embodiment” or other variants thereof do not necessarily refer to the same embodiments. Unless otherwise specified, one or more particular features and / or elements described in connection with one or more embodiments may be found in one embodiment, or may be found in more than one embodiment, or may be found in all embodiments, or may be found in no embodiments. Although one or more features and / or elements may be described herein in the context of only a single embodiment, or in the context of more than one embodiment, or in the context of all embodiments, the features and / or elements may instead be provided separately or in any appropriate combination or not at all. Conversely, any features and / or elements described in the context of separate embodiments may alternatively be realized as existing together in the context of a single embodiment.

[0033] Any particular and all details set forth herein are used in the context of some embodiments and therefore should not necessarily be taken as limiting factors to the proposed disclosure.

[0034] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by “comprises... a” does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

[0035] In traditional Radio Access Networks (RANs), particularly with the advent of 5G and O-RAN architectures, functionalities of a base station are divided into different logical layers or protocol stacks. The functionalities can be flexibly split between centralized units (CUs) and Distributed Units (DUs or RUs), depending on performance requirements, fronthaul capabilities, and deployment models. Figure 1 illustrates a Third Generation Partnership Project (3GPP) 100 having eight functional splits, in accordance with the conventional techniques. The 3GPP 100 has proposed eight functional split options (1 to 8) 102a, 102b, 102c, 102d, 102e, 102f, 102g, and 102h including several sub-options. The eight functional split options (1 to 8) 102a, 102b, 102c, 102d, 102e, 102f, 102g, and 102h include Radio Resource Control (RRC), Packet Data Convergence Protocol (PDCP), high RLC, low RLC, high Medium Access Control (MAC), low MAC, high Physical Layer (PHY), low PHY, and Radio Frequency (RF). The RRC manages control plane signaling, mobility, handover, connection setup, and reconfiguration. The RRC typically resides in the CU, closer to a core network. The PDCP provides header compression, security (ciphering or integrity), and reordering of data packets. The PDCP handles control and user plane data. Higher-layer splits (e.g., the RRC, the PDCP) reduce fronthaul bandwidth requirements but limit real-time control over radio resources.

[0036] The high RLC is responsible for error correction through retransmission, in-sequence delivery, and flow control. The high RLC typically resides in the CU. Further, the low RLC performs segmentation and reassembly of data packets into RLC protocol data units (PDUs). The high MAC handles scheduling decisions, logical channel multiplexing, and resource allocation. The high MAC resides in the DU, requiring real-time processing. The low MAC performs Hybrid Automatic Repeat request (HARQ), multiplexing, and demultiplexing of MAC PDUs. The low MAC is deployed closer to the RU for low-latency operations. The high PHY handles channel coding or decoding, modulation or demodulation, and other physical layer processes. The high PHY is often placed in the O-RAN Distributed Unit (O-DU) for flexibility. Further, the low PHY and RF manage Fast Fourier Transform (FFT) or Inverse Fast Fourier Transform (IFFT), beamforming, precoding, and the conversion of digital signals to analog RF signals for transmission. Lower-layer splits (e.g., MAC, PHY) require very high fronthaul bandwidth and ultra-low latency to maintain real-time performance, making them difficult to implement over non-ideal transport networks.

[0037] Figure 2 illustrates a 7.2x split architecture 200, in accordance with the conventional techniques. The 7.2x split architecture 200 includes downlink physical layer processing chain splits across O-RAN functional split between the O-DU and the O-RU. The 7.2x split architecture 200 includes Primary / Secondary Synchronization Signals (PSS / SSS) 202a, a Physical Broadcast Channel (PBCH) 202b, a Physical Downlink Control Channel (PDCCH) 202c, a Physical Downlink Shared Channel (PDSCH) 202d, a Phase Tracking Reference Signal (PTRS) 202e, Channel State Information Reference Signal (CSI-RS) 202f.

[0038] Baseband processing at the O-DU side includes a signal generation block 204a, a scrambling block 204b, or a Demodulation Reference Signal (DMRS) generation block 204c. The signal generation block 204a creates various physical signals required for synchronization, cell identification, and reference purposes. The generated signals ensure that a User Equipment (UE) can detect, synchronize, and decode information transmitted by a gNodeB (gNB) to the UE. The scrambling block 204b is the process of randomizing the data bits before modulation to minimize interference, avoid long sequences of zeros or ones, and ensure uniform power spectral density. The Demodulation Reference Signal (DMRS) generation block 204c generates a reference signal embedded in data transmissions to help the UE estimate the radio channel and properly demodulate received data. The received data refers to the radio signal or transmission received by the UE from the O-RU over a wireless communication link. The data transmissions refer to downlink data signals sent from the O-RU to the UE over the radio interface. Modulation block 204d maps bits to complex modulation symbols (Quadrature Phase Shift Keying (QPSK), 16 Quadrature Amplitude Modulation (QAM), 64QAM, etc.). The bits represent fundamental binary information units (0s and 1s) carrying user or control data, which are grouped and converted into complex modulation symbols in the modulation block 204d.

[0039] For the PDSCH 202d, a layer mapping block 206 maps modulated symbols onto spatial layers. Subsequently, a precoding block 208 performs spatial processing (Multiple Input Multiple Output (MIMO)) techniques and adapts signal for each antenna port. Thereafter, a Resource Element mapping block 210 maps the modulated or pre-coded symbols to subcarriers and Orthogonal Frequency Division Multiplexing (OFDM) symbols. An in-phase (I) and Quadrature (Q) compression block 212a compresses the data to reduce size, while an IQ decompression block 212b performs decompression as needed.

[0040] In the 7.2x split architecture 200, the O-RU is responsible for performing analog-to-digital conversion, time domain processing, Cyclic Prefix (CP) removal or addition. The O-RU also executes Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) operations along with signal and optional compression. Meanwhile, the O-DU handles channel estimation, equalization, and the rest of the physical layer (L1) and a data link layer (L2) operations. Notably, most of the L1 processing in the 7.2x architecture 200 happens in the O-DU, simplifying the processing at the O-RU. The real-time aspects of control and user plane communication with the O-RU are controlled by the O-DU. For example, the O-RAN Working Group 4 (Open Fronthaul Interfaces WG) Control, User, and Synchronization Plane Specification, (O-RAN.WG4.CUS.0-R003-v12.00)

[0041] Beamforming 214 is an optional operation performed by the O-RU. The beamforming 214 adjusts the signal phase and amplitude for each antenna. The Inverse Fast Fourier Transform (IFFT) and Cyclic Prefix (CP) addition converts the signal from a frequency-domain to a time-domain and adds a cyclic prefix to combat inter-symbol interference (OFDM processing). Finally, a Digital to analog conversion block 218 converts the digital signals into analog form, preparing the analog signal for transmission over the RF interface.

[0042] Figure 3 illustrates a block diagram showing a new functional Split 300 for an X-MIMO BSs, in accordance with the conventional techniques. A Radio Frequency Front End (RFFE) 301a is a hardware block in a wireless communication device (like a base station or mobile device) that handles RF signal transmission and reception. A Fronthaul (FH) 301b refers to a communication link connecting the O-DU 304 to the O-RU 302.

[0043] The X-MIMO is an extremely large, massive MIMO having an increased number of antennas at the BS (of the orders of 1000s). In order to support the X-MIMO scenario, the new split is introduced where the O-RU 302 has some additional functionalities. The additional functionalities include SRS processing and the port reduction.

[0044] In the SRS processing, the O-RU 302 processes the SRS signal by extracting the REs 306a carrying SRS from the UEs, estimating the channel 306b across the REs, and obtaining the CSI corresponding 306c to each UE. The estimated channel matrix will also be employed to obtain a precoder matrix which is applied to the downlink signal before being converted to the time domain signal.

[0045] In the Port Reduction 308, the O-RU 302 receives a signal from NRXantennas at the BS, where the NRXantennas are in a large number in the case of the X-MIMO, so the O-RU 302 cannot simply send data worth NRXstreams to the O-DU 304 as the O-RU 302 will choke the front-haul link. Therefore, the new split introduced a port reduction module that combines these NRXstreams and sends only NLstreams to the O-DU 304 thereby maintaining the front-haul bandwidth limit.

[0046] Additionally, in the 7.2x functional split, the higher function splits promote simpler functionalities at the O-RU 302 making it simple for the implementation. Also, for harnessing the benefits of centralized processing, most processing is done at the O-DU 304. However, the 7.2x functional split has certain limitations in the high front-haul overhead, the only basic analog and lower PHY processing are done at the O-RU 302 and most of the received signals need to be sent to the O-DU 304 for complete processing. The sending beamforming weights from the O-DU 304 to the O-RU 302 for performing precoding at the O-RU 302. The higher the number of streams, the larger the front-haul throughput.

[0047] In the O-DU 304, Downlink High PHY Transmit per Layer (DL High PHY Tx per Layer) refers to high-level PHY processing of downlink data for each MIMO layer before transmission. Further, Uplink High PHY Transmit / Receive Layer (UL High PHY Tx / Rx Layer) 312a refers to the high PHY layer operations related to uplink data transmitted by the UE and received by the network. A soft De-modulation 312b is a technique used to convert received symbols into soft bits instead of hard decisions (0 or 1). A layer De-Mapping 312c is a reverse of layer mapping; the layer De-Mapping 312c separates the received combined signal into individual MIMO layers for decoding. Minimum Mean Square Error Interference Rejection Combining (MMSE IRC) is an advanced receiver technique combining MMSE equalization with interference rejection.

[0048] Figure 4 illustrates a block diagram 400 and a table for the DL DMRS Processing at the O-DU, in accordance with the conventional techniques. Typically, in the 7.2x split or the new split for X-MIMO, the DL DMRS processing happens at the O-DU 304 with the aid of the L2 messages that the O-DU 304 receives over the FAPI interface. An L2 software 402 sends Functional Application Platform Interface Physical Downlink Shared Channel Protocol Data Unit (FAPI PDSCH PDU) 404 which consists of parameters related to DMRS generation and RE mapping.

[0049] In order to obtain the DMRS REs, the O-DU 304 using the information elements from the PDSCH PDU obtains the time and frequency domain mapping of the DMRS sequence in the resource grid. The information along with the parameters from the PDSCH PDU is utilized by the O-DU 304 to compute the DMRS sequence for each layer and each UE. However, transferring the DMRS symbols from the O-DU 304 to the O-RU 302 incurs significant overhead on the front-haul link as shown in a Table 1 below:

[0050] [Table 1]

[0051]

[0052] Figure 5 illustrates a plot 500 between the DMRS Mapping type and the DMRS Configuration Type, in accordance with the conventional techniques. In the DMRS having a 5thgeneration (5G) New Radio (NR) is a reference signal specific to each UE wherever used by the UE to estimate the radio channel for coherent data demodulation. The parameters for DMRS in 5G NR include the following equation (1):

[0053]

[0054] DMRS scrambling ID {0,1,2,...,65535} used for sequence generation. or = DL DMRS sequence initialization {0 or 1} used for sequence generation. dmrs_type=DL DMRS Configuration Type (type1 or type2) used for RE mapping. dmrs_type=DL DMRS Configuration Type (type1 or type2) used for RE mapping. dmrs_typeA_pos = DL DMRS type A symbol mapping {post2 or pos3}. dmrs_typeA_pos = DL DMRS type A symbol mapping {post2 or pos3}. dmrs_AdditionalPos = additional DMRS symbol mapping ({pos1, pos2,pos3,pos4}. Single or double = defines if single or double symbols are used for DMRS, = number of CDM groups without data.

[0055] In addition, the PDSCH DMRS consists of three parts. The PDSCH DMRS Mapping Type, to determine the starting position of the PDSCH DMRS symbol in a slot in a Time Domain. THE PDSCH DMRS Configuration Type, to determine the density of PDSCH DMRS RE's in the frequency domain. The PDSCH DMRS Additional Position is used for channel estimation and demodulation for high-speed mobility conditions where channel conditions vary rapidly.

[0056] The DMRS in 5G network (NR) for sequence generation and RE mapping, in accordance with the conventional techniques. First the initialization sequence　is calculated using the scrambling ID, the slot number, the number of symbols in a slot, and other parameters as shown in the below equations,

[0057]

[0058]

[0059] Then, the two sequences　 　and　 　are generated for creating the scrambling sequence　c(n)　described in the above equations). The DMRS sequence r(m)　is generated using the scrambling sequence, involving complex number calculations to produce the final sequence. Finally, the DMRS symbols are obtained by scaling the DMRS sequence with a precoding matrix　 　and a sequence of phase shifts　 .

[0060] In addition, during RE mapping, the Frequency domain location (k) of each RE is determined based on a predefined equation, as specified in the standard DMRS generation and mapping procedure. Also, time domain location (l) is determined by a predefined table and predefined value.

[0061] A table 2 showing DMRS specific parameters, and the description, in accordance with the conventional techniques.

[0062] [Table 2]

[0063]

[0064] In the FAPI PDSCH PDU, there are some other parameters in the PDSCH PDU that define the resource allocation and bandwidth part utilization that are also used at the O-DU 304 to generate the DMRS sequence and perform the RE mapping.

[0065] As explained previously, there is a huge front-haul bandwidth required for transferring the DL DMRS symbols from the O-DU 304 to the O-RU 302. There exist L2 FAPI messages related to the DMRS that instruct the O-DU 304 to perform the DMRS generation and the RE mapping in the downlink.

[0066] However, with the feature being moved to the antenna side (O-RU 302), there will be a significant reduction in the bandwidth consumption with reduced complexity at the O-DU 304 while not introducing significant complexity at the O-RU 302. Moreover, an equivalent FAPI message will need to be transferred between the O-DU 304 and the O-RU 302 to aid the DL DMRS generation at the O-RU 302. Therefore, there needs to be a C-Plane message that may carry the DMRS configuration information from the O-DU 304 to the O-RU 302 with all the derived parameters obtained at the O-DU 304. In the existing architecture, there are no such C-Plane section types or section extensions that cater to the DMRS-related information flow between the O-DU 304 and the O-RU 302.

[0067] Under a given split architecture, the offloading of the DL DMRS processing to the O-RU 302 is performed. The offloading facilitates the reduction in the front-haul and the bandwidth along with the transfer of the DMRS-related information between the O-DU 304 and the O-RU 302, without excessively utilizing the front-haul bandwidth.

[0068] The drawbacks / difficulties or the disadvantages / limitations of conventional techniques explained in the background section are just for exemplary purposes and the disclosure would never limit its scope only such limitations. A person skilled in the art would understand that this disclosure and below mentioned description may also solve other problems or overcome the other drawbacks / disadvantages of the conventional arts which are not explicitly captured above.

[0069] Embodiments of the present disclosure will be described below in detail with reference to the accompanying drawings.

[0070] Figure 6 illustrates a block diagram depicting an environment 600 for transmitting a Demodulation Reference Signal (DMRS) sequence, in accordance with an embodiment of the present disclosure. The environment 600 may include a baseband unit (BBU) 602, an Open Radio Access Network (O-RAN) Radio Unit (O-RU) 608, one or more Resource Elements (RE) 610a, 610b, 610c,..., 610n, and a User Equipment (UE) 612. The BBU 602 may include an O-RAN centralized unit (O-CU) 604, and an O-RAN distributed unit (O-DU) 606. Further, the O-RAN Radio Unit (O-RU) 608 may include a system 614. In an embodiment, the system 614 may be implemented within the O-RU 608. In another embodiment, the system 614 may be externally connected to the O-RU 608. Further, in another embodiment, some part of the system 614 may be externally connected to the O-RU 608 and another part of the system 614 may be implemented within the O-RU 608. The system 108 is described in greater detail in conjunction with Figure 7.

[0071] The BBU 602 may be a central processing unit responsible for handling baseband signal processing functions in a network. The BBU 602 may be configured to perform layer 2 and higher layer 1 processing. The BBU 602 may include an O-RAN centralized unit (O-CU) 604 and an O-RAN Distributed Unit (O-DU) 606.

[0072] The O-CU 604 may be a logical node within the BBU 602 that handles higher-layer protocol processing in an O-RAN architecture. The O-CU 604 may be configured to manage Radio Resource Control (RRC) and Packet Data Convergence Protocol (PDCP) layers. Further, the O-CU 604 may be configured to handle control plane (CP) signaling and user plane (UP) data processing. The O-CU 604 may be configured to send configuration parameters to the O-DU 606, including DMRS parameter sets for downlink transmission.

[0073] In an embodiment, the O-DU 606 may be a logical node within the BBU 602 that handles time-critical, lower-layer protocol processing. Further, the O-DU 606 may be configured to manage Radio Link Control (RLC), Medium Access Control (MAC), and High Physical (PHY) Layer operations. Further, the O-DU 606 may be responsible for scheduling, Hybrid Automatic Repeat request (HARQ), and resource allocation. Further, the O-DU 606 may be configured to generate a reduced parameter set for DMRS generation (like slot timing and resource mapping). The reduced parameter set may include a subset of original parameters selected or optimized to reduce complexity, dimensionality, or computational load while retaining sufficient information for the intended analysis, modeling, or operation. Tables and the expressions may be used at the O-DU 606 in order to obtain the reduced parameter set to be transferred from the O-DU 606 to the O-RU 608 as part of the DMRS configuration. The reduced parameter set has been further detailed in the Tables 3, 4, and 5,

[0074] Table 3 includes the reduced parameter set required at the O-RU 608, in accordance with the embodiment of the present disclosure. Seven parameters or derived parameters from the FAPI PDSCH may be shown in the Table 3.

[0075] [Table 3]

[0076]

[0077] Based on the DMRS config parameters and derived parameters, the present disclosure proposes the offloading of the DL DMRS generation processing to the O-RU 608 to reduce the front-haul overhead in massive or X-MIMO scenarios and the transfer of the DMRS configuration over the C-Plane message from the O-DU 606 to the O-RU 608 with the reduced parameter set. In order to transfer information between the O-DU 606 and the O-RU 608, a New C-Plane Section Type (ST X) consists of the derived parameters that are obtained in the O-DU 606 for the DMRS configuration.

[0078] The Table 4 includes a bit-level resolution of a new Section Type in the ORAN C-Plane, in accordance with the embodiment of the present disclosure. The bit level resolution of each parameter may be identified by using the maximum value that each parameter may take as per 3rd Generation Partnership Project (3GPP) 5thgeneration (5G) Network (NR) specifications.

[0079] [Table 4]

[0080]

[0081] The below table 5 includes a new Section Type in ORAN C-Plane sending the DMRS configuration, in accordance with the embodiment of the present disclosure. The new section type for sending the DMRS configuration from the O-DU 606 to the O-RU 608 may be represented as the ST X. The parameters included may aid the O-RU 608 in generating the DMRS signal. ST X may define the DMRS configuration on a per UE ID basis (or layer-wise). In the new functional splits, the SRS processing and the port reduction may be performed at the O-RU 608, making the O-RU 608 comparatively computationally intensive. The lower front-haul throughput as port-reduced data may be transferred to the O-DU 606. Therefore, there is no need to transfer beamforming weights for precoder or port reduction.

[0082] [Table 5]

[0083]

[0084] The reduced parameter set may eliminate the requirement of storing tables at the O-RU 608 and excessive computation at the O-RU 608.

[0085] The reduced parameter set required for the DMRS sequence generation include

[0086] The may be obtained from a Functional Application Platform Interface Physical Downlink Shared Channel Protocol Data Unit (FAPI PDSCH PDU). The and may be obtained using a slot indication by FAPI messages.

[0087] The O-DU 606 may be configured to communicate with the O-RU 608 via an O-RAN fronthaul interface. In an embodiment, the O-RU 608 may be configured to receive the reduced parameter set associated with DMRS configuration from the O-DU 606. The DMRS configuration may include a C-Plane Section Type (ST X). The C-Plane Section Type (ST X) may include derived parameters that are obtained in the O-DU 606 for the DMRS configuration.

[0088] Upon receiving the reduced parameter set, the O-RU 608 may be configured to generate a randomized bit stream. The randomized bit stream may include, but is not limited to, a pseudo-random sequence. The randomized bit stream may be generated using one or more Pseudo-Noise sequences. For example, parameters are computed and gold sequences 　and　 are used to create the pseudo-random sequence which is for the DMRS. The pseudo-random sequence is used to produce the final DMRS sequence at the O-RU 608.

[0089] The parameters required for time domain mapping include l' and having a . and l' are obtained for PDSCH mapping Type A relying on DMRS-Type A-Position while for PDSCH mapping Type B, is 0.

[0090] The parameters required for frequency mapping may include,

[0091]

[0092] k'=0, 1, n=0, 1,..., is given by 38.211 - Table 7.4.1.1.2-1 and Table 7.4.1.1.2-2.

[0093] The O-RU 608 may be configured to determine the DMRS sequence using the generated randomized bit stream. Further, the O-RU 608 may be configured to identify one or Orthogonal Frequency Division Multiplexing (OFDM) symbols carrying the DMRS sequence based on the reduced parameter set received from the O-DU 606.

[0094] The O-RU 608 may be configured to transmit the determined DMRS sequence over the one or more REs 610a, 610b, 610c,..., 610n in a frequency domain to the UE 612. The REs 610a, 610b, 610c,..., 610n may refer to a smallest unit of time-frequency resources allocated for data transmission or control signaling. Each RE 610a, 610b, or 610c,...or 610n may typically include one subcarrier (frequency domain) for the duration of one Orthogonal Frequency Division Multiplexing (OFDM) symbol (time domain).

[0095] The O-RU 608 may be configured to obtain one or more DMRS symbols based on the determined DMRS sequence for maintaining reliable communication between the O-RU 608 and the UE 612. The one or more DMRS symbols may be required to estimate the characteristics of a wireless channel. The characteristics may include, but are not limited to, fading, interference, phase shifts, and the like. An accurate channel estimation may allow the UE 612 to decode the transmitted data correctly. The UE 612 may be configured to use the one or more DMRS symbols as a reference to remove channel impairments from the received signal and correctly retrieve the transmitted data. Further, the O-RU 608 may be configured to scale the DMRS sequence with a precoding matrix before transmission to the UE 612.

[0096] Figure 7 illustrates a block diagram of the system 614, in accordance with an embodiment of the present disclosure. The system 614 is to be implemented in transmitting the DMRS sequence to the UE 612.

[0097] The system 614 may include, but is not limited to, one or more processors 702, a memory 704, an input / output (I / O) interface 708, one or more modules 710, and data 712. The one or more modules 710 and the memory 204 may be coupled to the one or more processors 702. The memory 704 may be configured to store the reduced parameter set.

[0098] As a non-limiting example, the one or more processors 702 can be a single processing unit or several units, all of which could include multiple computing units. The one or more processors 702 may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, state machines, logic circuitries, and / or any devices that manipulate signals based on operational instructions. Among other capabilities, the one or more processors 702 are adapted to fetch and execute computer-readable instructions and data stored in the memory 704. Among other capabilities, the one or more processors 702 may be configured to fetch and execute computer-readable instructions and data stored in the memory 704.

[0099] The one or more processors 702 may include one or a plurality of processors. The plurality of processors is further implemented as a general-purpose processor, such as a central processing unit (CPU), an application processor (AP), or the like, a graphics-only processing unit, such as a graphics processing unit (GPU), a visual processing unit (VPU), and / or an AI-dedicated processor such as a neural processing unit (NPU). The plurality of processors may control the processing of the input data in accordance with a predefined operating rule or an artificial intelligence (AI) model stored in the memory 704. The predefined operating rule or the AI model is provided through training or learning.

[0100] The one or more processors 702 may be disposed in communication with one or more input / output (I / O) devices via an Input / Output (I / O) interface 708. The I / O interface 708 may employ communication code-division multiple access (CDMA), high-speed packet access (HSPA+), global system for mobile communications (GSM), long-term evolution (LTE), WiMax, and the like, etc. In another embodiment of the present invention, the I / O interface 708 may employ ethernet, industrial wireless Local Area Network (LAN), Process Field Bus (PROFIBUS), Actuator Sensor (AS) Interface, and the like.

[0101] The memory 704 may be configured to store instructions executable by the one or more processors 702. In one embodiment, the memory 704 may communicate via a bus within the system 614. The memory 704 may include, but is not limited to, a non-transitory computer-readable storage media, such as various types of volatile and non-volatile storage media including, but not limited to, random access memory, read-only memory, programmable read-only memory, electrically programmable read-only memory, electrically erasable read-only memory, flash memory, magnetic tape or disk, optical media and the like. In one example, the memory may include a cache or random-access memory (RAM) for the one or more processors 702.

[0102] In alternative examples, the memory 704 may be separate from the one or more processors 702 such as a cache memory of a processor, the system memory, or other memory. The memory 704 may be an external server or a database for storing data. The memory 704 may be operable to store instructions executable by the one or more processors 702. The functions, acts, or tasks illustrated in the figures or described may be performed by the programmed processor for executing the instructions stored in the memory 704. The functions, acts, or tasks are independent of the particular type of instruction set, storage media, processor, or processing strategy and may be performed by software, hardware, integrated circuits, firmware, micro-code, and the like, operating alone or in combination. Likewise, processing strategies may include multiprocessing, multitasking, parallel processing, and the like.

[0103] The plurality of modules 710, amongst other things, may include routines, programs, objects, components, data structures, etc., which perform particular tasks or implement data types. The plurality of modules 710 may also be implemented as, signal processor(s), state machine(s), logic circuitries, and / or any other device or component that manipulates signals based on operational instructions.

[0104] Further, the plurality of modules 710 may be implemented in hardware, instructions executed by a processing unit, or by a combination thereof. The processing unit may comprise a computer, a processor, such as the one or more processors 702, a state machine, a logic array, or any other suitable devices capable of processing instructions.

[0105] The processing unit may be a general-purpose processor which executes instructions to cause the general-purpose processor to perform the required tasks, or, the processing unit may be dedicated to performing the required functions. In another embodiment of the present disclosure, the plurality of modules 710 may be machine-readable instructions (software) which, when executed by a processor / processing unit 702, perform any of the described functionalities.

[0106] In an embodiment, the plurality of modules 710 may include the reduced parameter set receiving module 716, a randomized bit stream generating module 718, a DMRS sequence determining module 720, a DMRS sequence transmitting module 722, a DMRS symbols obtaining module 724, a sequence of phase shift obtaining module 726, and an OFDM symbols identifying module 728.

[0107] The reduced parameter set receiving module 716 may be responsible for receiving the reduced parameter set from the O-DU 606. The reduced parameter set may include essential configuration information required to generate the DMRS sequence without requiring the full parameter load, optimizing the fronthaul bandwidth. The reduced parameter set may include , dmrsConfigType, , l', , and other values necessary for the RE mapping, sequence generation, and phase shift calculation. The reduced set may help the O-RU 608 generate the DMRS locally, reducing processing load on the O-DU 606 and fronthaul overhead.

[0108] The randomized bit stream generating module 718 may be configured to generate the randomized bit stream based on the received reduced parameter set. The randomization may involve using pseudo-random sequences such as a Gold sequence, or other pseudo-noise (PN) sequences. The randomized bit stream may include, but is not limited to, the pseudo-random sequence. The generated bit stream may serve as the base input for creating the DMRS sequence, ensuring randomness and low cross-correlation properties beneficial for channel estimation.

[0109] The DMRS sequence determining module 720 may be configured to apply sequence generation techniques. The sequence may be scaled or weighted using precoding matrices if the MIMO is deployed. The DMRS sequence determining module 720 may ensure that the DMRS sequence meets the required properties such as orthogonality, correlation, and robustness.

[0110] The DMRS sequence transmitting module 722 may be configured to map and transmit the determined DMRS sequence over the one or more REs 610a, 610b, 610c,..., 610n in the frequency domain. The transmission may be done toward the UE 612 to enable channel estimation and demodulation of data symbols. The DMRS sequence transmitting module 722 may ensure that the DMRS is transmitted within the correct OFDM symbols, as specified by the DMRS configuration. The DMRS sequence transmitting module 722 may support MIMO layers and precoding, where applicable.

[0111] The DMRS symbols obtaining module 724 may be responsible for generating or obtaining the DMRS symbols by scaling the DMRS sequence with the precoding matrix. The DMRS symbols may be actual complex modulated symbols mapped onto the REs 610a, 610b, 610c,..., 610n. Further, the DMRS symbols obtaining module 724 may include precoding that optimizes transmission for the MIMO by improving beamforming and spatial multiplexing capabilities. The DMRS symbols are what the UE 612 eventually receives and uses for demodulation reference.

[0112] The sequence of phase shifts obtaining module 726 may be configured to obtain the sequence of phase shifts based on the reduced parameter set. The sequence of phase shifts (w_t(l')) may be used to generate orthogonal DMRS sequences across different layers or antenna ports. The phase shift sequence may ensure orthogonality between multiple DMRS instances, reducing interference in multi-user or multi-layer MIMO scenarios. The sequence of phase shifts obtaining module 726 may be configured to compute values for k' = 0, 1, and l' based on time or frequency domain positioning.

[0113] The OFDM symbols identifying module 728 may be configured to identify the one or more OFDM symbols that are used to carry the DMRS sequence. The identification is based on parameters such as , l', and , which define the symbol indices in a time domain. The OFDM symbols identifying module 728 may ensure correct DMRS positioning for proper channel estimation by the UE 612.

[0114] Further, the memory 704 may include an operating system 714 for performing one or more tasks of the system 614, as performed by a generic operating system in the communications domain. The data 712 may serve, amongst other things, as a repository for storing data processed, received, and generated by one or more of the plurality of modules 710. In an embodiment, the plurality of modules 710 may be configured to perform various operations or steps that may be discussed and explained in detail in conjunction with Figure 8.

[0115] Figure 8 illustrates a flowchart depicting an exemplary method 800 for transmitting the DMRS sequence to the UE 612, in accordance with an embodiment of the present disclosure. The method 800 may be a computer-implemented method executed, for example, by the one or more processors 702 and the module(s) 710. For the sake of brevity, constructional and operational features of the system 614 that are already explained in the description of Figure 6, Figure 7, and Figure 8, are not explained in detail in the description of Figure 8.

[0116] At step 802, the method 800 may include receiving, at the O-RU 608, the reduced parameter set associated with DMRS configuration from the O-DU 606.

[0117] The O-RU 608 receives the minimized set of parameters necessary for the DMRS generation instead of a full configuration. The minimized set of parameters reduces overhead on the fronthaul interface, enabling efficient communication between the O-DU 606 and the O-RU 608. For example, the O-DU 606, during the downlink PDSCH transmission setup, sends only the essential parameters to the O-RU 608 instead of the complete RRC-configured DMRS setup. For instance, in the Massive MIMO scenario, where bandwidth is precious, reduced parameters help save transmission resources.

[0118] Upon receiving the reduced parameter set, the method 800 may include generating, by the O-RU 608, the randomized bit stream. The randomized bit stream may be generated using the one or more Pseudo-Noise sequences.

[0119] Using then_idor other relevant seed values from the reduced parameter set, the O-RU 608 generates the pseudo-random bit stream. The Pseudo-Noise (PN) sequence generators (like Gold Sequence, m-sequence) provide random-like behavior while being deterministic. The randomized bit stream forms the basis for modulation and sequence creation. For example, suppose the n_id value is 512, the O-RU 608 uses the value as the seed to generate the PN sequence. The generated bit stream may help form the complex DMRS symbols used for channel estimation at the UE 612.

[0120] At step 806, the method 800 may include determining, by the O-RU 608, the DMRS sequence　using the generated randomized bit stream.

[0121] The randomized bit stream is modulated and mapped to create the DMRS sequence. The DMRS sequence is configured to have low cross-correlation with other sequences, allowing clear channel estimation. In an example, for 2x2 MIMO, two separate DMRS sequences are generated for each layer. The O-RU 608 applies cyclic shift parameters to ensure orthogonality.

[0122] At step 808, the method 800 may include transmitting, by the O-RU 608, the determined DMRS sequence over the one or more REs 610a, 610b, 610c,..., 610n in a frequency domain to the UE 612 using the reduced parameter set.

[0123] The DMRS sequence is mapped onto specific REs 610a, 610b, 610c,..., 610n within the OFDM symbols identified by the parameter. The REs 610a, 610b, 610c,..., 610n are basic time-frequency units defined by subcarrier frequency and OFDM symbol index. The UE 612 receives the DMRS REs and uses DMRS the REs to estimate the channel for data demodulation. For example, in a 20 MHz channel, the O-RU 608 maps the DMRS sequence onto the REs 610a, 610b, 610c,..., 610n of the 3rd and 11th OFDM symbols within a slot. The UE 612 receives the DMRS symbols. The UE 612 performs channel estimation to equalize the received data symbols in adjacent REs 610a, 610b, 610c,..., 610n.

[0124] The method 800 may include obtaining, by the O-RU 608, the one or more DMRS symbols based on the determined DMRS sequence for maintaining reliable communication between the O-RU 608 and the UE 612.

[0125] The method 800 may include scaling, by the O-RU 608, the DMRS sequence with the precoding matrix before transmission to the UE 612.

[0126] The method 800 may include obtaining, by the O-RU 608, the sequence of phase shifts based on the determined DMRS sequence.

[0127] The method 800 may include identifying, by the O-RU 608, the one or more Orthogonal Frequency Division Multiplexing (OFDM) symbols carrying the DMRS sequence based on the reduced parameter set received from the O-DU 606.

[0128] The embodiments disclosed herein can be implemented through at least one software program running on at least one hardware device and performing network management functions to control the elements. The elements can be at least one of a hardware device or a combination of hardware devices and software modules.

[0129] In various embodiments, the present disclosure at least provides advantages such as:

[0130] ▶ The present disclosure significantly reduces the data load on the fronthaul link; by transmitting only the reduced parameter set from the O-DU to the O-RU instead of a complete DMRS sequence, the invention significantly reduces the data load on the fronthaul link.

[0131] ▶ The present disclosure enables the O-RU to generate the DMRS sequence locally using a randomized bit stream, minimizing dependency on the O-DU for repetitive signaling. The present disclosure reduces latency and allows faster sequence generation closer to the antenna.

[0132] ▶ The present disclosure provides offloading DMRS sequence generation to the O-RU improves scalability by distributing processing workloads, allowing support for massive MIMO systems and a larger number of User Equipments (UEs) without increasing the O-DU processing burden.

[0133] ▶ The locally generated DMRS sequence, tailored using the reduced parameter set, provides reliable channel estimation references for the UE, leading to improved demodulation performance and overall link quality, especially in high-mobility or dense deployments.

[0134] ▶ The present disclosure allows the O-RU to dynamically generate DMRS sequences based on updated parameters received from the O-DU. This flexibility supports various deployment scenarios, including small cells, macro cells, and beamforming operations.

[0135] ▶ The present disclosure ensures efficient use of radio resources while maintaining robust channel estimation performance, by transmitting the DMRS sequence over selected REs in the frequency domain.

[0136] ▶ The present disclosure provides the offloading DMRS sequence generation and certain processing tasks to the O-RU reduces the computational load and power requirements at the O-DU, contributing to overall energy-efficient network operation.

[0137] ▶ The present disclosure provides the local DMRS generation at the O-RU supports real-time adaptability for beamforming adjustments and MIMO processing, improving coverage, capacity, and reliability in challenging radio environments.

[0138] It is understood that terms including "unit" or "module" at the end may refer to the unit for processing at least one function or operation and may be implemented in hardware, software, or a combination of hardware and software.

[0139] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.

[0140] The drawings and the forgoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein.

[0141] Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.

[0142] Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any component(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all the claims.

[0143] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of at least one embodiment, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Claims

1.A method (800) performed by an open radio access network (O-RAN) radio unit (O-RU) (608) for transmitting a demodulation reference signal (DMRS) sequence, the method (800) comprising:receiving (802) a reduced parameter set associated with DMRS configuration from an O-RAN-distributed unit (O-DU) (606);upon receiving the reduced parameter set, generating (804) a randomized bit stream;determining (806) the DMRS sequence　using the generated randomized bit stream; andtransmitting (808) the determined DMRS sequence over one or more resource elements (REs) (610a, 610b, 610c,...,610n) in a frequency domain to a user equipment (UE) (612) using the reduced parameter set.2.The method (800) of claim 1, comprising:obtaining one or more DMRS symbols based on the determined DMRS sequence for maintaining reliable communication between the O-RU (608) and the UE (612).3.The method (800) of claim 2, wherein obtaining the one or more DMRS symbols comprises:scaling the DMRS sequence with a precoding matrix before transmission to the UE (612).4.The method (800) of claim 1, wherein the randomized bit stream is generated using one or more Pseudo-Noise sequences.5.The method (800) of claim 1, comprising:obtaining a sequence of phase shifts based on the determined DMRS sequence.6.The method (800) of claim 1, wherein generating the randomized bit stream comprises:identifying one or more orthogonal frequency division multiplexing (OFDM) symbols carrying the DMRS sequence based on the reduced parameter set received from the O-DU (606).7.An open-radio access network (O-RAN)-radio unit (O-RU) (608) for transmitting a demodulation reference signal (DMRS) sequence, wherein the O-RU (608) is configured:receive a reduced parameter set associated with DMRS configuration from an O-RAN-distributed unit (O-DU) (606),upon receiving the reduced parameter set, generate a randomized bit stream,determine the DMRS sequence　using the generated randomized bit stream, andtransmit the determined DMRS sequence over one or more resource elements (REs) (610a, 610b, 610c,...,610n) in a frequency domain to a user equipment (UE) (612) using the reduced parameter set.8.The O-RU (608) of claim 7, wherein the O-RU (608) is configured to:obtain one or more DMRS symbols based on the determined DMRS sequence for maintaining reliable communication between the O-RU (608) and the UE (612).9.The O-RU (608) of claim 8, wherein the O-RU (608) is configured to:scale the DMRS sequence with a precoding matrix before transmission to the UE (612).10.The O-RU (608) of in claim 7, wherein the randomized bit stream is generated using one or more Pseudo-Noise sequences.11.The O-RU (608) of claim 7, wherein the O-RU (608) is configured to:obtain a sequence of phase shifts based on the determined DMRS sequence.12.The O-RU (608) as claimed in claim 7, wherein to generate the randomized bit stream, the O-RU (608) is configured to:identify one or more orthogonal frequency division multiplexing (OFDM) symbols carrying the DMRS sequence based on the reduced parameter set received from the O-DU (606).

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