Method and apparatus for decomposed radio access network

Abstract

The invention relates to a method and apparatus for a decomposed radio access network. There is provided an apparatus comprising: a memory; and a processor configured to: determine, for a remote interference management reference signal, a first frequency domain sequence comprising a plurality of first frequency domain symbols, where each first frequency domain symbol corresponds to a subcarrier of the plurality of subcarriers; determining a second frequency domain sequence comprising a plurality of second frequency domain symbols, where each second frequency domain symbol on a respective subcarrier comprises a phase rotated version of a respective first frequency domain symbol on the respective subcarrier in which the respective first frequency domain symbol is phase rotated based on the respective subcarrier and the cyclic prefix length; and instructing to transmit information representing the second frequency domain sequence and the first frequency domain sequence to a radio unit of the cellular network for transmission in a continuous orthogonal frequency division multiplexing symbol.

Description

Technical Field

[0001] This disclosure generally relates to methods and apparatus for use in disaggregated radio access networks. Background Technology

[0002] In radio communication networks based on many radio communication technologies, such as fourth-generation (LTE) and fifth-generation (5G) New Radio (NR), various methods are employed to provide wireless data transmission with the desired efficiency, speed, and reliability. Traditional Radio Access Networks (RANs) employ integrated systems where the entire process of transmitting and receiving radio communication signals is performed. In such traditional RANs, network access nodes can implement the entire network stack, including the Physical Layer (PHY), Medium Access Control (MAC), Radio Link Control (RLC), and Packet Data Convergence Control (PDCP).

[0003] In various deployments of recently emerging RAN architectures (e.g., Open Radio Access Network (O-RAN) architectures), network access nodes can have functions partitioned across multiple units, aiming to meet the demand for increased capacity by providing a flexible and interoperable approach to the RAN. There are many methods for providing this partitioning across multiple units. In one example, a baseband unit (BBU) can be partitioned into: i) a control unit (CU) (e.g., O-CU), primarily responsible for non-real-time operation, hosting the control plane for Radio Resource Control (RRC) and the PDCP protocol; and ii) a distributed unit (DU) (e.g., O-DU), primarily responsible for real-time operation, hosting functions such as RLC layer functions, MAC layer functions, and higher PHY functions. A radio unit (RU) (e.g., O-RU) hosting lower PHY functions can receive radio communication signals from terminal equipment and provide data streams to the DU via a fronthaul interface (e.g., Open Fronthaul). Summary of the Invention

[0004] According to one aspect of this application, an apparatus is provided, comprising: a memory; and a processor configured to: determine, for a Remote Interference Management Reference Signal (RIM-RS), a first frequency domain sequence comprising a plurality of first frequency domain symbols, wherein each of the plurality of first frequency domain symbols corresponds to a subcarrier among a plurality of subcarriers; determine, a second frequency domain sequence comprising a plurality of second frequency domain symbols, wherein each of the plurality of second frequency domain symbols on a corresponding subcarrier among the plurality of subcarriers includes a phase-rotated version of a corresponding first frequency domain symbol on the corresponding subcarrier, wherein the phase-rotated version is phase-rotated based on the corresponding subcarrier and a cyclic prefix (CP) length; and instruct to transmit information representing the second frequency domain sequence and the first frequency domain sequence to a radio unit of a cellular network for transmission in consecutive orthogonal frequency division multiplexing (OFDM) symbols.

[0005] According to another aspect of this application, an apparatus is provided, comprising: a memory; and a processor configured to: generate a first frequency domain sequence for a remote interference management reference signal (RIM-RS); generate a phase ramp signal based on a cyclic prefix (CP) length associated with a transmission of a radio unit in a cellular network; multiply the phase ramp signal by the first frequency domain sequence to obtain a second frequency domain sequence; and map the first frequency domain sequence and the second frequency domain sequence to consecutive first and second OFDM symbols.

[0006] According to another aspect of this application, a non-transitory computer-readable medium is provided, comprising one or more instructions that, if executed by a processor, cause the processor to perform the following operations: determining, for a Remote Interference Management Reference Signal (RIM-RS), a first frequency domain sequence comprising a plurality of first frequency domain symbols, wherein each of the plurality of first frequency domain symbols corresponds to a subcarrier among a plurality of subcarriers; determining, a second frequency domain sequence comprising a plurality of second frequency domain symbols, wherein each of the plurality of second frequency domain symbols on a corresponding subcarrier among the plurality of subcarriers includes a phase-rotated version of a corresponding first frequency domain symbol on the corresponding subcarrier, wherein the phase-rotated version is phase-rotated based on the corresponding subcarrier and a cyclic prefix (CP) length; and instructing that information representing the second frequency domain sequence and the first frequency domain sequence be transmitted to a radio unit of a cellular network for transmission in consecutive OFDM symbols. Attached Figure Description

[0007] In the accompanying drawings, similar reference numerals generally refer to the same parts in different views. The drawings are not necessarily to scale, and the emphasis is generally on illustrating the principles of this disclosure. In the following description, various aspects of this disclosure are described with reference to the following drawings, in which:

[0008] Figure 1 An exemplary radio communication network is shown;

[0009] Figure 2 An exemplary internal configuration of a communication device is shown;

[0010] Figure 3 An illustrative example associated with a network access node is shown;

[0011] Figure 4 An example of a radio communication network is shown;

[0012] Figure 5 Illustrative examples of the baseband processing entity and the radio unit are shown;

[0013] Figure 6 An illustrative example of the time-domain representation of RIM-RS is shown;

[0014] Figure 7 Examples of apparatuses according to various aspects of this disclosure are shown;

[0015] Figure 8 An illustrative example of two consecutive OFDM symbols is shown;

[0016] Figure 9 An illustrative example of communication resources in the time domain is shown;

[0017] Figure 10A An example of the application of the phase ramp signal is shown in the figure;

[0018] Figure 10B An illustrative example of phase reset during modulation and up-conversion is shown;

[0019] Figure 11 Examples of processes according to various aspects of this disclosure are shown;

[0020] Figure 12 An exemplary radio access network architecture is shown, in which the radio access network is decomposed into multiple units;

[0021] Figure 13 An example of the method is shown. Detailed Implementation

[0022] The following detailed description takes into account the accompanying drawings, which illustrate exemplary details and aspects in which various aspects of the present disclosure may be implemented.

[0023] In traditional cellular systems (such as 2G / 3G), signal processing for each cell is limited to fixed hardware resources, such as the Base Transceiver Station (BTS). In 3G / 4G, the decomposition of a single radio network access node was introduced by including a Remote Radio Unit (RRU) and a Base Unit (BBU), followed by the O-RAN architecture for 4G / 5G / 6G, where the decomposition involves O-RU, O-DU, and O-CU.

[0024] Furthermore, the concept of Virtualized RAN (vRAN) is introduced, which can also be viewed as encompassing aspects related to the decomposition and virtualization of various components associated with traditional RAN. In the vRAN concept, various functions performed by specific hardware elements are virtualized and transformed into software-based functions that can run on standard hardware platforms. Previously introduced hardware components (e.g., RRUs and BBUs) have been decomposed into software-based entities. The vRAN concept also includes standardized and open interfaces for interoperability between different hardware platforms, independent of vendor-specific implementations, thereby enabling a more open and flexible network ecosystem.

[0025] In the context of cellular networks, Remote Interference Management (RIM) refers to techniques and mechanisms used to mitigate interference between neighboring cells. Interference occurs when a signal transmitted from one cell (e.g., by a network access node or user equipment (UE) in that cell) interferes with signals received in a neighboring cell (e.g., by other network access nodes or UEs in neighboring cells). This interference can degrade communication quality and reduce network performance. RIM strategies aim to minimize this interference to improve spectral efficiency, increase capacity, and enhance overall network performance.

[0026] Key aspects of Restricted Information Management (RIM) in cellular networks can include interference estimation, interference coordination, beamforming and antenna techniques, dynamic spectrum management, and interference cancellation. Interference estimation refers to the aspect where a UE or network access node estimates interference levels by analyzing received signals, measuring channel conditions, and assessing the quality of received data. This estimation includes interference from neighboring UEs or cells operating in the same frequency band. Interference coordination refers to the aspect where a UE or network access node coordinates its transmission strategies to minimize interference with neighboring UEs or cells. This coordination may involve adjusting transmission power levels, selecting appropriate modulation and coding schemes, and implementing interference-aware scheduling algorithms. Beamforming and antenna techniques for RIM refer to the UE or network access node using beamforming and antenna techniques to focus transmit and receive beams onto intended communication partners while minimizing interference from other directions. Beamforming is particularly effective for reducing interference in dense deployment scenarios. Dynamic spectrum management for RIM refers to the UE or network access node dynamically managing the allocation of frequency resources to mitigate interference and optimize spectrum utilization. This may involve techniques such as dynamic frequency selection, spectrum sharing, and interference-aware resource allocation. Interference cancellation in RIM refers to the use of interference cancellation techniques by the UE or network access node to mitigate the impact of interference on the received signal. This can include spatial interference cancellation at the receiver or advanced signal processing algorithms that separate the desired signal from the interference source.

[0027] For RIM purposes, cellular networks (LTE, 5G / NR, 6G, etc.) may employ a designated reference signal used in cellular communication systems, particularly in the context of mitigating interference between neighboring cells. This designated reference signal is called the RIM Reference Signal (RIM-RS). Neighboring cells can utilize the RIM-RS to estimate and mitigate interference caused by transmissions from neighboring cells. For example, a network access node may transmit the RIM-RS to neighboring cells via a designated resource block or subframe. The network infrastructure can manage the allocation of resources used for RIM-RS transmission. By analyzing the received RIM-RS signal, neighboring cells can infer channel conditions and interference levels, and based on this, radio network entities (e.g., other network access nodes or UEs in neighboring cells) can adjust transmission parameters and interference mitigation techniques accordingly.

[0028] According to the various aspects described herein, the signal attributes of RIM-RS transmitted by a BS (e.g., time-domain attributes such as duration, cyclic prefix (CP) length, CP arrangement taking into account a specified resource grid configuration, etc.) may differ from the attributes of other radio communication signals transmitted by the same BS, some of which are described in this disclosure. In a decomposed radio network architecture that includes radio units providing lower-layer (e.g., lower PHY) functionality of the network stack and baseband units providing higher-layer (e.g., higher PHY) functionality of the network stack, this distinction may require further signaling exchanged from the baseband unit to the radio unit, which may indicate the allocation and / or presence of RIM-RS in a specified resource element of the resource grid, so that the radio unit correctly configures radio communication resources (time and frequency resources) to transmit RIM-RS.

[0029] However, the above methods may increase network overhead and configuration complexity on the radio unit side, as the radio unit may need to switch from a previous configuration for RF transmission of other signals (signals other than RIM-RS, such as uplink user data, other reference signals, etc.) to a specific configuration for transmitting RIM-RS, and then switch back to the previous configuration for further RF transmission of other signals. Specifically, considering the evolution of the O-RAN architecture, which includes the O-DU as part of the baseband unit and the O-RU as the radio unit, the aspects provided in this disclosure allow for the generation of RIM-RS waveforms in a manner fully compliant with the O-RAN partitioning between the O-DU and O-RU, achieving the improvements described herein.

[0030] The apparatus and methods disclosed herein may utilize or be related to radio communication technologies. While some examples may refer to specific radio communication technologies, the examples provided herein can be similarly applied to a variety of other radio communication technologies, whether existing or not, especially where such radio communication technologies share similar features as disclosed with respect to the examples below. The various exemplary radio communication technologies that the apparatus and methods described herein may utilize include, but are not limited to: Global System for Mobile Communications (“GSM”) radio communication technologies, Universal Packet Radio Service (“GPRS”) radio communication technologies, GSM Evolution Enhanced Data Rate (“EDGE”) radio communication technologies and / or 3rd Generation Partnership Project (“3GPP”) radio communication technologies, such as Universal Mobile Telecommunications System (“UMTS”), Freedom of Multimedia Access (“FOMA”), 3GPP Long Term Evolution (“LTE”), 3GPP Long Term Evolution Advanced (“LTE Advanced”), Code Division Multiple Access 2000 (“CDMA2000”), Cellular Digital Packet Data (“CDPD”), Mobitex, and 3G. Circuit-Switched Data (“CSD”), High-Speed ​​Circuit-Switched Data (“HSCSD”), Universal Mobile Telecommunications System (“3G”) (“UMTS(3G)”), Wideband Code Division Multiple Access (Universal Mobile Telecommunications System) (“W-CDMA(UMTS)”), High-Speed ​​Packet Access (“HSPA”), High-Speed ​​Downlink Packet Access (“HSDPA”), High-Speed ​​Uplink Packet Access (“HSUPA”), High-Speed ​​Packet Access Enhanced (“HSPA+”), Universal Mobile Telecommunications System-Time Division Duplex (“UMTS-TDD”), Time Division-Code Division Multiple Access (“TD-CDMA”), Time Division-Synchronous Code Division Multiple Access (“TD-CDMA”), 3GPP Partner Program Version 8 (4G Pre-4G) (“3GPP”) 3GPP Rel.8 (Pre-4G), 3GPP Rel.9 (3rd Generation Partnership Project Version 9), 3GPP Rel.10 (3rd Generation Partnership Project Version 10), 3GPP Rel.11 (3rd Generation Partnership Project Version 11), 3GPP Rel.12 (3rd Generation Partnership Project Version 12), 3GPP Rel.13 (3rd Generation Partnership Project Version 13), 3GPP Rel.14 (3rd Generation Partnership Project Version 14), 3GPP Rel.15 (3rd Generation Partnership Project Version 15), 3GPP Rel.16 (3rd Generation Partnership Project Version 16), 3GPP Rel.17 (3rd Generation Partnership Project Version 17), 3GPP Rel.18 (3rd Generation Partnership Project Version 18), 3GPP 4G, 3GPP LTE Extra, LTE-Advanced Pro, LTE Licensed Assisted Access (“LAA”), MuLTEfire, UMTS Terrestrial Radio Access (“UTRA”), Evolved UMTS Terrestrial Radio Access (“E-UTRA”), Long Term Evolution Advanced (4G) (“LTE Advanced (4G)”), cdmaOne (“2G”), Code Division Multiple Access 2000 (3G) (“CDMA2000 (3G)”), Evolved Data Optimized or Evolved Data Only (“EV-DO”), Advanced Mobile Telephone System (1G) (“AMPS (1G)”), Total Access Communications Deployment / Extended Total Access Communications Deployment (“TACS / ETACS”), Digital AMPS (2G) (“D-AMPS (2G)”), Push-to-talk (“PTT”), Mobile Telephone System (“MTS”), Improved Mobile Telephone System (“IMTS”), Advanced Mobile Telephone System (“AMTS”), OLT (Norwegian: Offentlig Landmobil Telefoni), MTD (Mobiltelefonisystem) D is the Swedish abbreviation for mobile phone systems, or D, Public Automatic Land Mobile (“Autotel / PALM”), ARP (Finnish, Autoradiopuhelin, “Car Radio Telephone”), NMT (Nordic Mobile Telephone), High Capacity Version of NTT (“Hicap”), Cellular Digital Packet Data (“CDPD”), Mobitex, DataTAC, Integrated Digital Enhanced Network (“iDEN”), Personal Digital Cellular (“PDC”), Circuit-Switched Data (“CSD”), Personal Handheld Telephone System (“PHS”), Broadband Integrated Digital Enhanced Network (“WiDEN”), iBurst, Unlicensed Mobile Access (“UMA”) (also known as 3GPP Universal Access Network, or GAN standard), Zigbee, etc. Wireless Gigabit Alliance (“WiGig”) standards, general mmWave standards (wireless systems operating in the 10-300 GHz and above, such as WiGig, IEEE 802.11ad, IEEE 802.11ay, etc.), technologies operating in the 300 GHz and THz bands and above (based on 3GPP / LTE, or IEEE 802.11p and others), vehicle-to-vehicle (“V2V”) and vehicle-to-X (“V2X”) and vehicle-to-infrastructure (“V2I”) and infrastructure-to-vehicle (“I2V”) communication technologies, 3GPP cellular V2X, DSRC (Dedicated Short Range Communications) communication deployments, such as intelligent transportation systems, and other existing, developing or future radio communication technologies.

[0031] The apparatus and methods described herein can be used with this radio communication technology under various spectrum management schemes, including but not limited to dedicated licensed spectrum, unlicensed spectrum, (licensed) shared spectrum (e.g., LSA = Licensed Shared Access in 2.3-2.4 GHz, 3.4-3.6 GHz, 3.6-3.8 GHz and other frequencies, and SAS = Spectrum Access System in 3.55-3.7 GHz and other frequencies), and can use various spectrum bands, including but not limited to IMT (International Mobile Telecommunications) spectrum (including 450-470 MHz, 690-960 MHz, 1710-2025 MHz, 2110-2200 MHz, 2300-2400 MHz, 2500-2690 MHz, 698-790 MHz, 610-790 MHz, 3400-3600 MHz, etc., some of which may be limited to (one or more) specific regions and / or countries), IMT Advanced spectrum, IMT-2020 spectrum (intended to include 3600-3800 MHz, 3 The spectrum includes the 0.5GHz band, the 600MHz band, and the bands in the 24.25-86GHz range, as well as the spectrum available under the FCC's "Spectrum Frontier" 4G initiative (including 27.5-28.35GHz, 29.1-29.25GHz, 31-31.3GHz, 37-38.6GHz, 38.6-40GHz, 42-42.5GHz, 47-64GHz, 64-71GHz, 61-76GHz, 81-86GHz, and 92-94GHz). The frequency bands include: 4.9 GHz (typically 4.85–5.925 GHz) and 63–64 GHz ITS (Intelligent Transportation Systems) bands; bands currently allocated to WiGig (e.g., WiGig band 1 (57.24–59.40 GHz), WiGig band 2 (59.40–61.56 GHz), WiGig band 3 (61.56–63.72 GHz), and WiGig band 4 (63.72–65.88 GHz)); the 60.2 GHz–71 GHz band; any band between 65.88 GHz and 61 GHz; bands currently allocated to automotive radar applications (e.g., 76–81 GHz); and future bands including 94–300 GHz and above. Furthermore, the apparatus and methods described herein can also be used secondary for radio communication technologies in bands such as TV blank bands (typically below 690 MHz), where, for example, the 400 MHz and 600 MHz bands are promising candidates. In addition to cellular applications, it can also address specific applications in vertical markets, such as PMSE (program production and special events), medical, health, surgical, automotive, low latency, and drone applications.Furthermore, the apparatus and methods described herein can also utilize radio communication technologies with hierarchical applications, such as introducing hierarchical priority ordering (e.g., low / medium / high priority, etc.) for different types of users through access based on spectrum-based priority differentiation, for example, giving the highest priority to Tier 1 users, then Tier 2 users, then Tier 3 users, and so on. The apparatus and methods described herein can also utilize radio communication technologies with different single-carrier or OFDM forms (CP-OFDM, SC-FDMA, SC-OFDM, filter bank-based multicarrier (FBMC), OFDMA, etc.) and, for example, 3GPP NR (New Radio), which may include allocating OFDM carrier data bit vectors to corresponding symbol resources.

[0032] Cellular wide-area radio communication technologies may include Global System for Mobile Communications (“GSM”), Code Division Multiple Access 2000 (“CDMA2000”), Universal Mobile Telecommunications System (“UMTS”), Long Term Evolution (“LTE”), Universal Packet Radio Service (“GPRS”), Evolved Data Optimized (“EV-DO”), GSM Evolution Enhanced Data Rate (“EDGE”), High Speed ​​Packet Access (HSPA; including High Speed ​​Downlink Packet Access (“HSDPA”), High Speed ​​Uplink Packet Access (“HSUPA”), HSDPA Enhanced (“HSDPA+”), and HSUPA Enhanced (“HSUPA+”)), Microwave Access Global Interoperability (“WiMax”) (e.g., WiMax Fixed or WiMax Mobile according to the IEEE 802.16 radio communication standard), and other similar radio communication technologies. Cellular wide-area radio communication technologies also include “small cells” of this technology, such as microcells, femtocells, and picocells. Cellular wide-area radio communication technologies may be collectively referred to herein as “cellular” communication technologies.

[0033] Figure 1 and Figure 2 The general network and device architectures used for wireless communication are described. Specifically, Figure 1An exemplary radio communication network 100 (e.g., a cellular communication network) is illustrated according to some aspects, which may include terminal devices 102 and 104 and network access nodes 110 and 120. The radio communication network 100 can communicate with the terminal devices 102 and 104 (i.e., mobile radio communication devices) via the radio access network through the network access nodes 110 and 120 (i.e., radio communication devices). While some examples described herein may relate to specific radio access network contexts (e.g., LTE, UMTS, GSM, other 3GPP networks, WLAN / WiFi, Bluetooth, 4G NR, mmWave, etc.), these examples are illustrative and can therefore be readily applied to any other type or configuration of radio access network. The number of network access nodes and terminal devices in the radio communication network 100 is exemplary and can be scaled to any number.

[0034] In an exemplary cellular context, network access nodes 110 and 120 may be base stations (e.g., eNodeB, NodeB, Base Transceiver Station (BTS), gNodeB, or any other type of base station), while terminal devices 102 and 104 may be cellular terminal devices (e.g., mobile station (MS), user equipment (UE), or any type of cellular terminal device). Network access nodes 110 and 120 can therefore interface with cellular core networks such as evolved packet core (EPC, for LTE), core network (CN, for UMTS), or other cellular core networks (e.g., via a backhaul interface), which may also be considered part of the radio communication network 100. The cellular core network may interface with one or more external data networks. In an exemplary short-range context, network access nodes 110 and 120 may be access points (APs, such as WLAN or WiFi APs), while terminal devices 102 and 104 may be short-range terminal devices (e.g., stations (STAs)). Network access nodes 110 and 120 may interface with one or more external data networks (e.g., via internal or external routers). Network access nodes 110 and 120 and terminal devices 102 and 104 may include one or more transmit / receive points (TRPs).

[0035] Network access nodes 110 and 120 (and optionally, Figure 1 Other network access nodes of the radio communication network 100 (not explicitly shown in the text) may accordingly communicate with terminal devices 102 and 104 (and optionally, Figure 1Other terminal devices (not explicitly shown in the text) of the radio communication network 100 are provided with a radio access network. In an exemplary cellular context, the radio access network provided by network access nodes 110 and 120 enables terminal devices 102 and 104 to wirelessly access the core network via radio communication. The core network provides switching, routing, and transmission of traffic data associated with terminal devices 102 and 104, and also provides access to various internal data networks (e.g., control nodes, routing nodes that transmit information between other terminal devices on the radio communication network 100, etc.) and external data networks (e.g., data networks that provide voice, text, multimedia (audio, video, images), and other Internet and application data).

[0036] The radio access network and core network of radio communication network 100 (if applicable, e.g., for a cellular context) can be constrained by communication protocols that may vary according to the characteristics of radio communication network 100. Such communication protocols define the scheduling, formatting, and routing of both user data traffic and control data traffic through radio communication network 100, including the transmission and reception of such data through both the radio access network domain and the core network domain of radio communication network 100. Therefore, terminal devices 102 and 104, as well as network access nodes 110 and 120, can follow the defined communication protocols to transmit and receive data through the radio access network domain of radio communication network 100, while the core network can follow the defined communication protocols to route data internally and externally. Exemplary communication protocols include LTE, UMTS, GSM, 5G / NR, 6G, WiMAX, Bluetooth, WiFi, mmWave, etc., any of which may be applicable to radio communication network 100.

[0037] In various aspects, network access nodes 110 and 120 may include one or more CUs, one or more DUs, and one or more RUs to communicate with terminal devices 102 and 104. In various examples, an RU may include a device configured to implement various processing functions of the RF. Specifically, an RU may implement lower PHY functions. A DU may include a device configured to implement various processing functions, particularly including higher PHY, MAC, and RLC functions. Those skilled in the art will recognize this as an example of network stack partitioning, and that DUs and RUs may have different partitioning configurations. An RU may be radio-linked to terminal devices 102 and 104 and linked to a DU via a fronthaul interface.

[0038] In various examples, the fronthaul interface can be configured to communicate via a fiber optic cable connection based on the Common Public Radio Interface (CPRI) or the Enhanced Common Public Radio Interface (eCPRI), but other communication media exist that can handle fronthaul communication. In any case, the RU can serve multiple end devices, and there may be limitations in link capacity and bandwidth regarding communication between the RU and the corresponding DU via fronthaul. Addressing some of these fronthaul limitations may be desirable.

[0039] Figure 2 Exemplary internal configurations of communication devices based on various aspects of this disclosure are illustrated. The communication devices may include aspects of the communication devices described in this disclosure (e.g., network access nodes 110, 120, BBU, CU, DU, or RU; note that some components described herein may differ) or aspects of mobile radio communication devices (e.g., terminal devices 102, 104). Communication device 200 may include a communication interface, which may optionally include an antenna system 202 and a radio frequency (RF) transceiver 204, a baseband modem 206 (including a digital signal processor 208 and a protocol controller 210), an application processor 212, and a memory 214. Although... Figure 2 While not explicitly stated, in some respects the communication device 200 may include one or more additional hardware and / or software components, such as processors / microprocessors, controllers / microcontrollers, other dedicated or general-purpose hardware / processors / circuits, (one or more) peripherals, memory, power supply, (one or more) external device interfaces, (one or more) subscriber identity modules (SIMs), user input / output devices ((one or more) displays, (one or more) keypads, (one or more) touchscreens, (one or more) speakers, (one or more) external buttons, (one or more) cameras, (one or more) microphones, etc.), or other related components.

[0040] Communication device 200 can transmit and receive radio signals over one or more radio access networks. Baseband modem 206 can bootstrap this communication function of communication device 200 according to the communication protocol associated with each radio access network and can perform control via a communication interface. The communication interface for the radio communication device may include antenna system 202 and RF transceiver 204 to transmit and receive radio signals according to formatting and scheduling parameters defined for each communication protocol. Those skilled in the art will recognize that communication device 200 may include another communication interface to perform communication with other communication devices within the communication network. While various practical designs may include separate communication components (e.g., separate antennas, RF transceivers, digital signal processors, and controllers) for each supported communication technology, for the sake of brevity, Figure 2The configuration of the communication device 200 shown depicts only a single instance of such a component.

[0041] Communication device 200 can utilize antenna system 202 to transmit and receive wireless signals. Antenna system 202 can be a single antenna or can include one or more antenna arrays, each antenna array including multiple antenna elements. For example, antenna system 202 can include an antenna array located on top of communication device 200 and a second antenna array located at the bottom of communication device 200. In some aspects, antenna system 202 may additionally include analog antenna combination and / or beamforming circuitry. In the receive (RX) path, RF transceiver 204 can receive analog radio frequency signals from antenna system 202 and perform analog and digital RF front-end processing on the analog radio frequency signals to generate digital baseband samples (e.g., in-phase / quadrature (IQ) samples) to provide to baseband modem 206. RF transceiver 204 can include analog and digital receiving components, including amplifiers (e.g., low-noise amplifiers (LNAs)), filters, RF demodulators (e.g., RF IQ demodulators), and analog-to-digital converters (ADCs), which RF transceiver 204 can utilize to convert the received radio frequency signals into digital baseband samples. In the transmit (TX) path, RF transceiver 204 can receive digital baseband samples from baseband modem 206 and perform analog and digital RF front-end processing on the digital baseband samples to generate analog radio frequency signals to provide to antenna system 202 for wireless transmission. RF transceiver 204 can therefore include analog and digital transmission components, including amplifiers (e.g., power amplifiers (PA)), filters, RF modulators (e.g., RF IQ modulators), and digital-to-analog converters (DACs), which RF transceiver 204 can utilize to mix the baseband samples received from baseband modem 206 and generate analog radio frequency signals for wireless transmission by antenna system 202. In some aspects, baseband modem 206 can control the radio transmission and reception of RF transceiver 204, including specifying the transmit and receive radio frequencies for the operation of RF transceiver 204.

[0042] like Figure 2As shown, the baseband modem 206 may include a digital signal processor 208, which can perform physical layer (PHY, Layer 1) transmit and receive processing to prepare outgoing transmit data provided by the protocol controller 210 for transmission via the RF transceiver 204 in the transmit path, and prepare incoming receive data provided by the RF transceiver 204 for processing by the protocol controller 210 in the receive path. The digital signal processor 208 may be configured to perform one or more of the following: error detection, forward error correction coding / decoding, channel coding and interleaving, channel modulation / demodulation, physical channel mapping, radio measurement and search, frequency and time synchronization, antenna diversity processing, power control and weighting, rate matching / dematching, retransmission processing, interference cancellation, and any other physical layer processing functions. The digital signal processor 208 may be structurally implemented as a hardware component (e.g., implemented as one or more digitally configured hardware circuits or an FPGA), a software-defined component (e.g., one or more processors configured to execute program code (e.g., software and / or firmware) defining operations, control, and I / O instructions stored in a non-transitory computer-readable storage medium), or a combination of hardware and software components. In some aspects, the digital signal processor 208 may include one or more processors configured to retrieve and execute program code defining control and processing logic for physical layer processing operations. In some aspects, the digital signal processor 208 may utilize software execution processing functions via the execution of executable instructions. In some aspects, the digital signal processor 208 may include one or more dedicated hardware circuits (e.g., ASICs, FPGAs, and other hardware) digitally configured to perform specific processing functions, wherein one or more processors of the digital signal processor 208 may offload certain processing tasks to these dedicated hardware circuits, which are referred to as hardware accelerators. Exemplary hardware accelerators may include Fast Fourier Transform (FFT) circuitry and encoder / decoder circuitry. In some respects, the processor and hardware accelerator components of the digital signal processor 208 can be implemented as coupled integrated circuits.

[0043] Communication device 200 can be configured to operate according to one or more radio communication technologies. Digital signal processor 208 can handle lower-layer processing functions (e.g., Layer 1 / PHY) of the radio communication technology, while protocol controller 210 can handle upper-layer protocol stack functions (e.g., data link layer / Layer 2 and / or network layer / Layer 3). Protocol controller 210 can therefore be responsible for controlling the radio communication components of communication device 200 (antenna system 202, RF transceiver 204, and digital signal processor 208) according to the communication protocol of each supported radio communication technology, and can accordingly represent the access layer and non-access layer (NAS) of each supported radio communication technology (also covering Layer 2 and Layer 3). Protocol controller 210 can be structurally implemented as a protocol processor configured to execute protocol stack software (retrieved from controller memory) and subsequently control the radio communication components of communication device 200 to transmit and receive communication signals according to the corresponding protocol stack control logic defined in the protocol software. Protocol controller 210 may include one or more processors configured to retrieve and execute program code defining upper-layer protocol stack logic for one or more radio communication technologies, which may include data link layer / layer 2 and network layer / layer 3 functions. Protocol controller 210 may be configured to perform both user plane and control plane functions to facilitate the transmission of application layer data to and from radio communication device 200 according to specific protocols of the supported radio communication technologies. User plane functions may include header compression and encapsulation, security, error checking and correction, channel multiplexing, scheduling and prioritization, while control plane functions may include radio bearer establishment and maintenance. The program code retrieved and executed by protocol controller 210 may include executable instructions defining the logic of such functions.

[0044] The communication device 200 may also include an application processor 212 and a memory 214. The application processor 212 may be a CPU and may be configured to process layers above the protocol stack, including the transport layer and the application layer. The application processor 212 may be configured to execute various applications and / or programs of the communication device 200 at the application layer of the communication device 200, such as an operating system (OS), a user interface (UI) to support user interaction with the communication device 200, and / or various user applications. The application processor may interface with the baseband modem 206 and serve as a source (in the transmission path) and a destination (in the reception path) of user data such as voice data, audio / video / image data, messaging data, application data, basic Internet / network access data, etc. In the transmission path, the protocol controller 210 can therefore receive and process the outgoing data provided by the application processor 212 according to the layer-specific functions of the protocol stack, and provide the obtained data to the digital signal processor 208. Digital signal processor 208 can then perform physical layer processing on the received data to generate digital baseband samples, which can then be provided to RF transceiver 204. RF transceiver 204 can then process the digital baseband samples to convert them into analog RF signals, which can then be wirelessly transmitted via antenna system 202. In the receiving path, RF transceiver 204 can receive and process the analog RF signals from antenna system 202 to obtain digital baseband samples. RF transceiver 204 can provide the digital baseband samples to digital signal processor 208, which can perform physical layer processing on the digital baseband samples. Digital signal processor 208 can then provide the obtained data to protocol controller 210, which can process the obtained data according to layer-specific functions of the protocol stack and provide the incoming data to application processor 212. Application processor 212 can then process the incoming data at the application layer, which may include using the data to execute one or more applications and / or presenting the data to a user via a user interface.

[0045] Memory 214 can implement the memory component of communication device 200, such as a hard disk drive or another such permanent storage device. Although Figure 2 It is not explicitly described in the text, but Figure 2 Various other components of the communication device 200 shown may each additionally include integrated permanent and non-permanent memory components, for example, for storing software program code, buffered data, etc.

[0046] According to some radio communication networks, terminal devices 102 and 104 can perform mobility procedures to connect to an available network access node of the radio access network of radio communication network 100, disconnect from an available network access node, and switch between available network access nodes. Since each network access node of radio communication network 100 may have a specific coverage area, terminal devices 102 and 104 can be configured to select and reselect available network access nodes to maintain a robust radio access connection with the radio access network of radio communication network 100. For example, terminal device 102 may establish a radio access connection with network access node 110, while terminal device 104 may establish a radio access connection with network access node 112. In the event of a deterioration of the current radio access connection, terminal device 102 or 104 may seek a new radio access connection with another network access node of radio communication network 100; for example, terminal device 104 may move from the coverage area of ​​network access node 112 to the coverage area of ​​network access node 110. As a result, the radio access connection with network access node 112 may deteriorate, which terminal device 104 can detect via radio measurements, such as signal strength or signal quality measurements of network access node 112. According to the mobility procedures defined in the appropriate network protocol for the radio communication network 100, terminal device 104 can seek a new radio access connection (this can be triggered, for example, at terminal device 104 or by the radio access network), for example, by performing radio measurements on nearby network access nodes to determine whether any nearby network access node can provide a suitable radio access connection. Since terminal device 104 may have moved to the coverage area of ​​network access node 110, terminal device 104 can identify network access node 110 (this can be selected by terminal device 104 or by the radio access network) and transfer to a new radio access connection with network access node 110. This mobility process (including radio measurements, cell selection / reselection, and handover) is established in various network protocols and can be adopted by terminal devices and radio access networks to maintain robust radio access connections between each terminal device and radio access network in any number of different radio access network scenarios.

[0047] Figure 3An illustrative example associated with a network access node is shown. The illustration shows a network access node system including DU 301 and RU 302. Fronthaul 303 connects DU 301 and RU 302. An interface (e.g., CPRI or eCPRI) may be used as the fronthaul interface. As provided in this disclosure, DU 301 may implement various functions of the PDCP, RLC, MAC, and PHY layers, and RU 302 may implement various functions of the PHY layer and RF functions to receive and transmit radio communication signals to a terminal device (i.e., UE) communicatively coupled to RU 302. The term "communcatively coupled to" may also be referred to as "attached to" or "served". The illustration shows only one RU 302 communicatively coupled to DU 301, but those skilled in the art will understand that DU 301 may be communicatively coupled to multiple RUs.

[0048] Illustratively, particularly in the O-RAN context, DU 301, when combined with RU 302 connected to it, can provide the gNB-DU functionality as defined in 3GPP TS 38.401. Note that DU 301 can be a virtual (i.e., logical) entity or a physical entity, and DU 301 can terminate the RLC, MAC, and High-PHY functions of the E2 and F1 interfaces, the open fronthaul interface, and the radio interface to the UE.

[0049] DU 301 can perform various functions in the PHY layer, which may differ from the PHY layer functions performed by RU 302. DU 301 can be deployed close to RU 302 in a commercial off-the-shelf (COTS) server field and communicate with RU 302 via fronthaul 303. For example, in a system configuration with a 7-2 function partitioning, DU 301 can perform higher PHY layer functions, including precoding, layer mapping, modulation, scrambling, rate matching, coding and block partitioning, and cyclic redundancy check (CRC) functions on the antenna port, while RU 302 can perform lower PHY layer functions, including cyclic prefix (CP) functions, fast Fourier transform (FFT) functions, beamforming and port expansion functions, and resource element mapping functions. RU 302 can also perform RF functions. In various examples, DU 301 and RU 302 can be configured to operate using various function partitioning configurations, particularly different downlink and uplink configurations.

[0050] Therefore, RU 302 may include a transceiver configured to receive and transmit radio communication signals to multiple terminal devices (e.g., UEs) that RU 302 may serve. RU 302 may include or be coupled to multiple antennas (e.g., an antenna array) to receive and transmit radio communication signals to the terminal devices. RU 302 may perform beamforming operations (e.g., by applying beamforming weights) to communicate with the terminal devices. In various examples, RU 302 may receive radio communication signals from the terminal devices and acquire baseband signals based on the radio communication signals received in the uplink. RU 302 may further acquire radio communication signals from the baseband signals and transmit radio communication signals to the terminal devices in the downlink.

[0051] RU 302 may also include a processor configured to perform various processing functions, particularly processing functions related to the defined network stack functions of RU 302. As provided with respect to this illustrative example, the processor of RU 302 may implement lower PHY functions, including those provided with respect to the illustrative example. Furthermore, the processor of RU 302 may include a controller to perform the various aspects provided in this disclosure. RU 302 may also include memory for storing data.

[0052] The transceiver of RU 302 can further perform operations communicating with DU 301. The transceiver of RU 302 may include circuitry for receiving and transmitting communication signals to / from DU 301 via fronthaul 303. Therefore, the processor of RU 302 can control the fronthaul interface and, after RU 302 performs the defined lower PHY layer functions on DU 301 via fronthaul 303, transmit communication signals based on the received radio communication signals, allowing DU 301 to further process the communication signals provided by RU 302 according to the various functions specified for DU 301. Similarly, DU 301 can perform the various processing functions specified for DU 301 and transmit communication signals to be transmitted to the terminal device to RU 302 via fronthaul 303. RU 302 can perform the defined lower PHY functions and RF functions of the communication signals to transmit the radio communication signals to the terminal device.

[0053] DU 301 may include a transceiver configured to receive and transmit communication signals to / from RU 302 via fronthaul 303. Furthermore, the transceiver of DU 301 may transmit and receive signals from a control unit (not shown) that performs various functions of the network stack via backhaul or midhaul. In various examples, a combination unit (e.g., a BBU) may include DU 301 such that RU 302 can be communicatively coupled to the BBU via fronthaul.

[0054] The DU may include a processor configured to perform various processing functions, particularly those related to the network stack functions defined for the DU 301. As provided with respect to this illustrative example, the processor of the DU 301 may implement RLC layer functions, MAC layer functions, and higher PHY functions, including those provided with respect to this illustrative example. Furthermore, the processor of the DU 301 may include a controller to perform the various aspects provided in this disclosure. The DU 301 may also include memory for storing data.

[0055] Based on the various aspects described herein, the illustrated connection via fronthaul 303 facilitates bidirectional data transfer between DU 301, which provides processing for higher network stack functions, and RU 302, which focuses on lower PHY layer operations. Illustratively, RU 302 can perform primary functions such as cyclic prefix (CP), FFT, beamforming, and RF, including processing baseband signals and radio communication signals received from end devices, while DU 301 can manage more complex tasks such as PDCP, RLC, MAC, and higher-layer PHY functions.

[0056] In addition, RU 302 can contribute by performing in-line beamforming operations (i.e., applying beamforming weights to facilitate communication with the terminal device). Essentially, this operation may require collaboration, as RU 302 performs beamforming based on signals received from DU 301 to obtain beamformed communication signals that will be transmitted to the terminal device.

[0057] Figure 4 An example of a radio communication network is illustrated. The radio communication network may include a DU 401 communicatively coupled to multiple RUs, such that each of the multiple RUs is coupled to DU 401 via a fronthaul (not shown), including a first RU 402, a second RU 403, and a third RU 404. Each RU may be located in different locations to serve different cell sectors, such that each RU can serve UEs in a sector, which may or may not overlap with another cell sector of another RU. In this example, the first RU 402 is configured to serve UEs in a first sector 412, the second RU 403 is configured to serve UEs in a second sector 413, and the third RU is configured to serve UEs in a third sector 414, and these cell sectors may overlap in some locations. In various examples, each RU may be configured to provide service to multiple UEs in substantially the same coverage area, where each UE may be served by more than one RU for joint processing.

[0058] Therefore, each RU can serve multiple UEs within its corresponding sector to receive and transmit radio communication signals from / to the UEs. In this illustrative example, the first RU 402 is configured to serve a first group of UEs including UE 422 and UE 426, and it can be said that the first group of UEs 422 is served by the first RU 402. The term "service" in this context can refer to a situation where there is a radio connection between entities, or a situation where a UE receives service at least for a layer of functionality related to the interconnection model of the network stack. This can include situations where the first RU 402 serves the first group of UEs 422; for example, the first RU 402 may be the serving cell of the first group of UEs, and it can be said that the first group of UEs 422 is being served by the first RU 402, and so on. Illustratively, each UE 422 is associated with the first RU 402 and with DU 401, as an RU-DU pair, which can also be referred to as a network element pair in this disclosure.

[0059] In this context, each UE 423 is associated with the second RU 403 and with DU 401 as a corresponding RU-DU pair. Similarly, each UE 424 is associated with the third RU 404 and with DU 401 as a corresponding RU-DU pair.

[0060] As described, there may be overlap in certain locations. In this regard, one of the UEs (i.e., UE 425) is described as follows: UE 425 can be positioned to receive service in the second cell sector 413 and the third cell sector 414. In other words, UE 425 is associated with the second RU 403 and the third RU 404, and with DU 401. Therefore, UE 425 is associated with the first RU-DU pair (i.e., the second RU 403 and DU 401) and with the second RU-DU pair (i.e., the third RU 404 and DU 401).

[0061] Similarly, UE 426 is described as receiving service from each of the first RU 402, the second RU 403, and the third RU 404, and is therefore served by all RUs 402, 403, and 404. In other words, UE 426 is associated with the first RU 402, the second RU 403, and the third RU 404, and with DU 401. Therefore, UE 426 is associated with the first RU-DU pair (i.e., the first RU 402 and DU 401), the second RU-DU pair (i.e., the second RU 403 and DU 401), and the third RU-DU pair (i.e., the third RU 404 and DU 401).

[0062] Therefore, each UE 422, 423, 424, 425 can receive and transmit radio communication signals from / to the corresponding RU 402, 403, 404 that the corresponding UE 422, 423, 424, 425 is serving. In such a contellation, particularly based on RU location, each RU may encounter interference regarding radio communication activities between other RUs and corresponding UE groups. For example, radio communication between each RU 402, 403, 404 and the corresponding group of UEs, as provided in this illustrative example, may be subject to interference based on radio communication signals exchanged between each other RU 402, 403, 404 and the corresponding group of UEs for each other RU 403, 404.

[0063] For example, radio communication between the first RU 402 and the first group of UEs may be interfered with by radio communication signals exchanged between the second RU 403 and the second group of UEs, and between the third RU 404 and the third group of UEs. Therefore, the radio communication between the first RU 402, the second RU 403 and the second group of UEs, and the radio communication between the third RU 404 and the third group of UEs can be referred to as interfering radio communication in this example. Similarly, other RUs such as the second RU 403 and the third RU 404 can be referred to as interfering RUs for the first RU 402, and the first group of UEs and the second group of UEs can be referred to as interfering UEs (e.g., interfering UEs) in this disclosure. In this illustrative example, since UE 425 is served by both the second RU 403 and the third RU 404, the interfering UEs of both the second RU 403 and the third RU 404 may not include UE 425, because UE 425 is served by both the second RU 403 and the third RU 404. In various examples, the RU can receive information indicating further relationships between the UE and other RUs from the corresponding UE that the RU is serving or from the DU that the RU is communication-coupled to.

[0064] Figure 5 Illustrative examples of baseband processing entities and radio units (e.g., RU (e.g., O-RU) 402 and DU (e.g., O-DU) 401, respectively) are shown, along with various functions associated with each entity according to a specified partitioning of the network stack for dividing the PHY functions of the protocol stack into LOW-PHY and HIGH-PHY. In this illustration, RU 401 may perform RF functions to receive and transmit radio communication signals from the UE, and the LOW-PHY functions include analog beamforming, digital-to-analog or analog-to-digital conversion, FFT / IFFT and cyclic prefix functions, digital beamforming, precoding, and IQ decompression.

[0065] DU 401 can be coupled to RU 402 via fronthaul 450. DU 401 can perform additional PHY functions, such as high-frequency PHY functions including remapping, precoding, layer mapping, symbol modulation, and scrambling. DU can also implement MAC and RLC operations. In some examples, CU can communicatively couple to DU 401 to perform further network operations above the RLC layer, such as RRC, PDCP, SDAP, etc. In some examples, DU can perform these operations.

[0066] According to the various aspects described herein, the BBU (e.g., DU 401) can determine (e.g., encode and / or generate) frequency domain symbols for OFDM symbols to be transmitted by the RU (RU 402). DU 401 can further map the generated frequency domain symbols to resource elements (e.g., OFDM symbols, subcarriers, and antenna ports, respectively) in the time and frequency domains (and spatial domain, if available) according to its allocation / scheduling operations. DU 401 can provide RU 401 with information representing the frequency domain symbols and allocation / scheduling (i.e., resource elements regarding the allocation of frequency domain symbols) via fronthaul interface 450. RU 402 handles the conversion from frequency domain symbols to time domain sampling and cyclic prefix insertion.

[0067] Figure 6 An illustrative example of the time-domain representation of RIM-RS is shown, depicting the time-domain waveform structure of RIM-RS. RIM-RS can span two OFDM symbols in the time domain, namely, the first symbol 601a and the second symbol 601b. By generating RIM-RS, RIM-RS can include a prefix portion 621 with a cyclic prefix 610, followed by the same first portion 622 and second portion 623. The cyclic prefix 610 of RIM-RS can be based on the last N symbols 611 of the second portion 623. Accordingly, in this illustration, the prefix portion 621 can be based on the corresponding portion 611 of the second portion 623. Note that RIM-RS spans the duration of two OFDM symbols, where one CP is provided for the duration of both OFDM symbols. The configuration of the radio access network can include a configuration such that each OFDM slot includes a CP with a specified CP length based on configuration digital parameters affecting subcarrier spacing, symbol duration, CP length, and frame and slot structure.

[0068] In other words, unlike conventional OFDM symbols used for communication (where a cyclic prefix is ​​pre-added to the front of each OFDM symbol), RIM-RS may include a special cyclic prefix followed by two RIM-RS inverse discrete Fourier transform (IDFT) periods corresponding to the frequency domain symbols generated for RIM-RS. Each RIM-RS IDFT period is formed by performing an IDFT on the vector of frequency domain symbols (including the frequency domain RIM-RS sequence). The duration of the RIM-RS IDFT period can be the same as the IDFT period of a conventional OFDM symbol. The duration of the cyclic prefix of RIM-RS can be equal to the duration of the two OFDM symbols covered by RIM-RS minus the duration of the two RIM-RS IDFT periods. The RIM-RS IDFT period can refer to the time period during which the frequency domain RIM-RS symbols of the frequency domain RIM-RS sequence are converted into time domain symbols through an internal inverse discrete Fourier transform operation.

[0069] Traditionally, RIM-RS is a time-continuous signal at antenna port p. It can be defined as:

[0070]

[0071] in: and Δf RIM =15·2 μ kHz, where μ∈{0,1} is the subcarrier spacing configuration of RIM-RS; k1 is the starting frequency offset of RIM-RS given in clause 7.4.1.6.4.3; It is the length of the RIM-RS sequence, where It refers to the bandwidth of RIM-RS in the resource block; the time slot in the frame. The starting position l0 of the RIM-RS type i∈{1,2} is determined by... The starting position of OFDM symbol l for the subcarrier spacing configuration μ in the subframe is given as follows, where l = l0; Where l = l0; κ is the basic time unit T of LTE. s The basic time unit T of NR c The ratio between them; The number of symbols per time slot.

[0072] Figure 7Examples of apparatuses for communication devices according to various examples of this disclosure are shown. Apparatus 700 may be a communication device (e.g., communication device 200) as described in various aspects herein. Specifically, apparatus 700 may include a BBU. In other words, apparatus 700 may be configured to operate as a BBU within a radio access network, configured to provide at least the higher PHY functions of the network stack within the radio access network. Specifically, apparatus 700 may be an O-DU (i.e., configured to provide O-DU functionality according to an O-RAN architecture).

[0073] The device 700 may include a processor 701, a memory 702, and a communication interface 703 configured to receive and transmit communication signals for communicating with other entities within a cellular network, including a radio access network. In some aspects, the communication interface 703 may include one or more signal paths to carry communication signals. The communication interface 703 may include one or more transceivers.

[0074] Processor 701 may include one or more processors, which may include a baseband processor and an application processor (e.g., application processor 212, baseband modem 206). In various examples, processor 701 may include a central processing unit (CPU), a graphics processing unit (GPU), a hardware acceleration unit (e.g., one or more dedicated hardware acceleration circuits (e.g., ASIC, FPGA, and other hardware)), a neuromorphic chip, and / or a controller. Processor 701 may be implemented in a processing unit (e.g., a system-on-a-chip (SOC) or processor). According to various examples, processor 701 may also provide further functionality to process received communication signals. Memory 702 may store various types of information required for the operation of processor 701 or communication interface 703 according to various aspects of this disclosure.

[0075] Communication interface 703 may include an RU interface 703R configured to communicate with a plurality of RUs (e.g., RU 610a-d). For example, RU interface 703R may include a dedicated port for each of the plurality of RUs, which receives and transmits communication signals to the respective RU. The respective port may couple device 700 to the respective RU among the plurality of RUs via a respective fronthaul interface. Similarly, communication interface 703 may include a CU interface configured to communicate with at least one CU. Communication interface 703 may be configured to provide communication with any entity according to the O-RAN architecture described herein.

[0076] Processor 701 can be configured to perform operations such that the BBU performs any of the operations described herein, especially according to Figure 3 and Figure 4The operation involves performing network stack operations, specifically the PDCP, RLC, MAC, and higher-layer PHY functions described for DU 301 and 401. Within these functions, processor 701 can determine the frequency domain symbols of downlink signals in the transmission direction for transmission by one or more RUs communicatively coupled to the BBU to the UE served by those RUs. To this end, processor 701 can perform operations as described in... Figure 5 The higher PHY processing described above. Processor 701 can accordingly cause (e.g., instruct) the BBU (e.g., cause communication interface 703) to send a communication signal including the determined frequency domain signal to the RU, such that the RU can perform lower PHY processing on the communication signal to transmit the corresponding RF signal. Lower PHY processing may include a transformation from the frequency domain to the time domain (e.g., IFFT, inverse fast Fourier transform) to obtain the corresponding RF signal. Lower PHY processing may also include CP insertion, wherein a CP is inserted within each OFDM symbol.

[0077] Figure 8 An illustrative example is shown of an RU configured to transmit two consecutive OFDM symbols, provided as a first OFDM symbol 801 and a second OFDM symbol 802. The first and second OFDM symbols can be successive consecutive symbols (e.g., the second OFDM symbol 802 follows the first OFDM symbol 801 in the time domain (i.e., the first OFDM symbol 801 is transmitted before the second OFDM symbol 802)). As described herein, an RU connected to a BBU including device 700 can be configured to perform lower PHY processing in a specified configuration, such that the RU inserts a CP for each OFDM symbol. This is in Figure 8 The middle part represents other communication signals. Figure 8 The OFDM symbol representation of RU transmission in the time domain is shown.

[0078] In other communication signals 800 (i.e., any of the communication signals other than RIM-RS 850), processor 701 can acquire (e.g., determine, generate, encode) frequency domain symbols. Processor 701 can further map the acquired frequency domain symbols to certain (e.g., determined) resource elements within the resource grid for transmission of RF signals based on (i.e., including) the acquired frequency domain symbols. Processor 701 can further perform other higher PHY functions on the acquired frequency domain symbols and cause the BBU to send communication signals representing the acquired frequency domain symbols to the RU.

[0079] Illustratively, processor 701 can acquire a first frequency domain symbol associated with the first OFDM symbol 801 and cause communication interface 703 to send the first frequency domain symbol to the RU. The processor of the RU can receive the first frequency domain symbol and perform a lower PHY function on it. The lower PHY function may include performing an IFFT on the first frequency domain symbol to obtain the IFFT1 812 described herein. The lower PHY function may also include a CP insertion of a certain CP length (e.g., time length), wherein the processor of the RU can copy the end portion of the IFFT 812 corresponding to the CP length and add the end portion of the IFFT 812 as a first CP 811 to the beginning of the first OFDM symbol 801.

[0080] Similarly, processor 701 can acquire a second frequency domain symbol associated with the second OFDM symbol 802 and cause communication interface 703 to send the second frequency domain symbol to the RU. The RU's processor can receive the second frequency domain symbol and perform a lower PHY function on it. The lower PHY function may include performing an IFFT on the second frequency domain symbol to obtain the IFFT2 822 described herein. The lower PHY function may also include a CP insertion of a certain CP length (e.g., time length), wherein the RU's processor can copy the end portion of IFFT 822 corresponding to the CP length and add the end portion of IFFT 822 as a second CP 821 to the beginning of the second OFDM symbol 802.

[0081] However, as shown herein, the configuration of RIM-RS 850 may differ from the configuration provided for other communication signals 800. Specifically, RIM-RS 850 may include CP 851, the length of which is twice the duration of the first CP 811 and the second CP 821. CP 851 may be followed by IFFTs of two identical sets of frequency domain symbols generated by processor 701. In other words, RIM-RS 850 may include CP 851, followed by a first IFFT 852 of a determined (e.g., generated) RIM-RS frequency domain sequence, and then a second IFFT 853 of a determined RIM-RS frequency domain sequence, wherein the first IFFT 852 and the second IFFT 853 are identical.

[0082] According to the aspects described herein, processor 701 can perform preprocessing on the generated RIM-RS frequency domain sequence and send the preprocessed frequency domain symbols to RU, such that when RU applies lower PHY processing based on the other communication signals mentioned above (i.e., applies IFFT and inserts the corresponding CP within each OFDM symbol), the two consecutive OFDM symbols obtained include CP 851, first IFFT 852, and second IFFT 853, as follows. Figure 8As stated above.

[0083] Processor 701 can generate a RIM-RS frequency domain sequence according to a method specified for the cellular network. To this end, processor 701 can determine (i.e. generate) a first frequency domain sequence comprising a plurality of first frequency domain symbols for RIM-RS 850, wherein each of the plurality of first frequency domain symbols corresponds to a subcarrier among a plurality of subcarriers. The plurality of subcarriers may correspond to resource elements (frequency domains) in which RIM-RS 850 is allocated for transmission.

[0084] Traditionally, the RIM-RS 850 can be used by network access nodes (e.g., gNBs) to measure inter-cell interference and provide information about the interference received to other gNBs. Illustratively, the processor 701 can utilize a reference sequence. Generate RIM-RS, where the pseudo-random sequence c(m) is a sequence of length M. PN The output sequence c(n) is associated with a pseudo-random sequence (where n = 0, 1, ..., M). PN -1) Defined as follows:

[0085] c(n)=(x1(n+N c )+x2(n+N c ))mod2

[0086] x1(n+31)=(x1(n+3)+x1(n))mod2

[0087] x2(n+31)=(x2(n+3)+x2(n+2)+x2(n+1)+x2(n))mod2

[0088] Where N C =1600, the first m-sequence x1(n) can be initialized as x1(0) = 1, x1(n) = 0, n = 1, 2, ..., 30. The second m-sequence x2(n) can be initialized by... This indicates that its value depends on the application of the sequence. In this cluster, processor 701 can initialize the pseudo-random sequence generator as follows: Where: n SCID ∈{0,1,…,2 10 -1}; Among them, pseudo-random sequence Initialize to Where the multiplier γ∈{0,1,…,2} 31 -1} and offset δ∈{0,1,…,2} 31 -1}; It is self The number of RIM-RS transmission cycles since then, of which It is relative to 00:00:00 on January 1, 1900. The time (in seconds) is calculated as continuous time, excluding leap seconds, and is traceable to a universal time base. This refers to the RIM-RS transmission periodicity (in seconds). Assume the first RIM-RS transmission cycle starts from... Beginning, and among them It is the total number of time slots in the RIM-RS transmission cycle.

[0089] Processor 701 can map a defined frequency domain sequence to a resource element configured for transmission of RIM-RS 850. Specifically, processor 701 can map a defined frequency domain sequence (i.e., the first frequency domain sequence) to a second OFDM symbol 802 in the corresponding frequency resource for transmission.

[0090] Note the RIM-RS 850 to be transmitted by the RU. The RIM-RS 850 may include the same IFFT portions (i.e., the first IFFT 852 and the second IFFT 853). Typically, if the RIM-RS 850 is compared with other communication signals 800, the portion 852a depicted within the boundary of the second OFDM symbol 802 is the portion inserted by the RU through a CP insertion operation. Note the presence of the same IFFT portions and the CP insertion operation (where the end portion of the CP length of the second IFFT 853 is inserted as the CP (e.g., the second CP 821)), the processor 701 can map the frequency domain symbols to the resource elements of the second OFDM symbol 802 without any alteration. Through the CP insertion on the RU side, the RU inserts portion 852a as the CP of the second OFDM symbol 802, which will actually correspond to the end portion of the first FFT 852, as shown herein. Accordingly, the processor 701 can cause the BBU to send information to the RU including the determined frequency domain sequence (i.e., the first frequency domain symbol), wherein the first frequency domain symbol will be transmitted within the second OFDM symbol 802. The processor 701 can also cause the BBU to send information indicating the resource element to which the first frequency domain symbol is mapped (e.g., the identifier of the second OFDM symbol 802 and the corresponding frequency / space resource).

[0091] To obtain the frequency domain symbols (referred to as second frequency domain symbols) to be mapped to the first OFDM symbol 801, processor 701 may determine a second frequency domain sequence comprising a plurality of second frequency domain symbols, wherein each of the plurality of second frequency domain symbols on a corresponding subcarrier among a plurality of subcarriers includes a phase-rotated version of a corresponding first frequency domain symbol on the corresponding subcarrier, in which the corresponding first frequency domain symbol is phase-rotated based on the corresponding subcarrier and the cyclic prefix (CP) length. In some examples, processor 701 may generate the second frequency domain sequence to which the frequency resources will be mapped by applying calculations based on the frequency resources (i.e., subcarriers) and the cyclic prefix configuration (e.g., CP length (i.e., CP duration)) according to the current configuration of the RU, such that the generated second frequency domain sequence includes the frequency domain symbols described herein. Through the mapping operation, processor 701 may obtain the second frequency domain sequence based on the first frequency domain sequence, the CP length, and the subcarrier configuration.

[0092] Note that each of the second frequency domain symbols on the corresponding subcarrier in the plurality of subcarriers may include a phase-rotated version of the corresponding first frequency domain symbol on the corresponding subcarrier, in which the corresponding first frequency domain symbol is phase-rotated based on the corresponding subcarrier and the cyclic prefix (CP) length.

[0093] To this end, processor 701 can acquire the first frequency domain symbol of the first frequency domain sequence and apply phase rotation on all subcarriers in a manner that the applied phase rotation increases linearly over multiple subcarriers. Therefore, the amount of phase rotation for each corresponding subcarrier can increase linearly over multiple subcarriers. For every two consecutive subcarriers in the multiple subcarriers, this can be described as the phase rotation amount increasing with the CP length.

[0094] In other words, processor 701 can determine phase shift parameters based on the CP length. The phase shift parameters can represent the phase shift increase for each subcarrier, indicating the amount by which processor 701 adjusts the phase of each subcarrier to achieve the desired effect. Processor 701 can accordingly adjust each first frequency domain symbol corresponding to each subcarrier by applying a frequency-dependent phase shift on the subcarriers. In other words, processor 701 can utilize the corresponding phase shift parameters to adjust the phase corresponding to each first frequency domain symbol to obtain the second frequency domain symbols of the second frequency domain sequence. The phase shift applied by processor 701 to each subcarrier can be proportional to the frequency. Accordingly, the phase shift applied by processor 701 can increase linearly with frequency. This allows the second frequency domain symbols to exhibit a linear phase profile on the subcarriers.

[0095] Once the processor 701 determines the second frequency domain sequence including the second frequency domain symbol provided in this disclosure, the processor 701 can map the second frequency domain sequence to a resource element configured for transmission of RIM-RS 850. Specifically, the processor 701 can map the second frequency domain sequence for transmission to a first OFDM symbol 801 in the corresponding frequency resource. Accordingly, the processor 701 can cause the BBU to send information including the second frequency domain sequence to the RU, wherein the second frequency domain symbol will be transmitted within the first OFDM symbol 801. The processor 701 can also cause the BBU to send information indicating the resource element to which the second frequency domain symbol is mapped (e.g., an identifier of the first OFDM symbol 801 and the corresponding frequency / space resource).

[0096] Figure 9 An illustrative example of a communication resource comprising multiple time slots in the time domain is shown, each time slot including multiple OFDM symbols. As shown in 901, processor 701 can map RIM-RS into time slots. In this illustrative example, processor 701 maps the first OFDM symbol 801 of RIM-RS 850 to the sixth OFDM symbol of time slot 3, and maps the second OFDM symbol 801 of RIM-RS 850 to the seventh OFDM symbol of time slot 3. In some examples, processor 701 can map RIM-RS at time slot boundaries as shown in 902, such that the RU can transmit the first OFDM symbol 801 of two consecutive OFDM symbols forming RIM-RS (e.g., the thirteenth OFDM symbol of time slot 2) in a first time slot, and the second OFDM symbol 801 of two consecutive OFDM symbols forming RIM-RS (e.g., the first OFDM symbol of time slot 3) in a second time slot following the first time slot.

[0097] In some examples, processor 701 can utilize a phase ramp signal to provide a conversion from a first frequency domain sequence to a second frequency domain sequence. Processor 701 can generate the phase ramp signal. Specifically, processor 701 can generate the phase ramp signal based on the CP length. Furthermore, the generation of the phase ramp signal can be based on multiple subcarriers, and specifically on the subcarrier spacing. The slope of the phase ramp signal in the time domain can be based on the CP length. Processor 701 can cause the BBU to send information representing the first frequency domain sequence to the RU, such that the first frequency domain sequence is mapped to a second OFDM symbol 802, while processor 701 can apply a phase rotation to the first frequency domain sequence using the phase ramp signal to obtain the second frequency domain sequence.

[0098] Figure 10AAn example of the application of a phase ramp signal according to various aspects described herein is illustrated. According to various aspects described herein, processor 701 can generate a phase ramp signal in the frequency domain. Processor 701 can accordingly multiply the frequency domain of the phase ramp signal (referred to herein as the phase ramp signal) with a first frequency domain sequence to obtain a second frequency domain sequence. Figure 10A In this process, processor 701 can map the first frequency domain sequence 1001 to resource elements including the second OFDM symbol 802. The number of resource blocks in the resource elements can be given as follows:

[0099]

[0100] To obtain a second frequency domain sequence mapped by processor 701 to the first OFDM symbol 801, processor 701 may multiply the frequency domain representation of the phase ramp signal with the first frequency domain sequence. In some examples, the multiplication may be element-wise, such that each element corresponding to a specific subcarrier of the phase ramp signal is multiplied by the corresponding first frequency domain symbol in the first frequency domain sequence for that specific subcarrier.

[0101] Note that, according to the distinctions described herein regarding the preprocessing of the frequency domain sequence of the RIM-RS with a duration of 2 OFDM symbols, where such distinctions exist, the second OFDM symbol 802 can be identical to the OFDM symbols of other communication signals 800, including the cyclic prefix and the RIM-RS IDFT region, depicted as 853. Simultaneously, the IDFT region of the first OFDM symbol 801 can be considered a cyclically shifted version of the RIM-RS IDFT region. If cyclically shifted, the cyclic shift amount is equal to the length of the cyclic prefix of the second OFDM symbol 802. Since the IDFT region of the second OFDM symbol 802 is identical to the RIM-RS IDFT region, the frequency domain symbol of the second OFDM symbol 802 mapped by the RIM-RS is identical to the RIM-RS sequence.

[0102] Since the IDFT region of the first OFDM symbol 801 is a cyclically shifted version of the RIM-RS IDFT region, the frequency domain symbol of the first OFDM symbol 801 mapped by RIM-RS is constructed by element-wise multiplication of the RIM-RS sequence and the phase ramp signal. The phase ramp signal can be a function of the cyclic offset, which is equal to the length of the cyclic prefix of the second OFDM symbol 802.

[0103] Based on the aspects provided in this article, the phase ramp signal can be expressed as R(n)=exp(-j·2π·n·SCS·T) CP,2nd )=exp(-j·2π·n·N CP,2nd / N FFT), where: n is the integer subcarrier index corresponding to the resource element to which the RIM-RS symbol is mapped; SCS is the subcarrier spacing in Hz; T CP,2nd This is the duration of CP, 2nd (e.g., in seconds) (1. For both 15K and 30K SCS: if the time slot boundary is crossed, then T) CP,2nd It can be equal to the CP of symbol 0 in a time slot with a specific length. 2. For 15K SCS: If the second symbol is symbol 7, then T CP,2nd It can be equal to a CP with a special length of 7; T CP,2nd The phase ramp signal affecting the first RIM-RS symbol; N CP,2nd N is the number of integer samples within the duration of CP,2nd at the applied sampling rate; FFT It is the number of integer samples taken within the duration of the FFT region at the applied sampling rate.

[0104] Accordingly, assume a 1,n Let represent a first frequency domain sequence, which includes the corresponding frequency domain symbol for each subcarrier index denoted by n. Then, a second frequency domain sequence a includes the corresponding frequency domain symbol for each subcarrier index n. 2,n It can be represented as a 2,n =R(n)xa 1,n ; x represents the element-wise multiplication of the corresponding subcarrier index.

[0105] Based on the aspects described herein, the RU can reset the phase of each OFDM symbol transmitted by the RU. Phase reset may include the following: Since the RU can operate without knowing the transmitted RIM-RS, the modulation and up-conversion of the OFDM baseband signal to the carrier frequency f0 for the antenna port p, subcarrier spacing configuration μ, and the assumed complex-valued OFDM symbol l in the subframe starting from t=0 can be performed by... Given. This reset makes the IDFT region (where The phase at the beginning of the RIM-RS signal is zero for a normal OFDM symbol. The RIM-RS signal may span two OFDM symbols, and only its first IFFT portion (where...) is... The phase at the beginning of ) can be set to zero, as by Given, among which This can be a configuration reference point for RIM-RS. Phase reset during modulation and up-conversion is as follows: Figure 10B As shown.

[0106] In the case of a phase reset, processor 701 can perform further operations on top of the above operations to compensate for the reset. For example, processor 701 can add another phase to each of the first OFDM symbol 801 and the second OFDM symbol 802 to ensure that the phase of the RIM-RS waveform generated at RU remains continuous over the two consecutive OFDM symbols. As described herein, this additional phase can be represented for the first frequency domain sequence and the second frequency domain sequence as follows: And φ. Illustratively, processor 701 can determine the presence of a reset based on information received from the RU. In other words, the aforementioned phase ramp signal of the first OFDM symbol 801 can be represented as... φ is the desired phase adjustment, which is equal to φ = 2πf0T CP,2nd Note that processor 701 can also apply the desired phase adjustment to the first frequency domain sequence (i.e., in the absence of a portion for acquiring the phase ramp signal of the second frequency domain sequence). For the second OFDM symbol, the phase compensation can be expressed as R(n) = It is the desired phase adjustment, equal to The aspects described herein may also include processor 701 acquiring a second frequency domain sequence without compensation based on the above examples, and applying phase compensation separately (e.g., before or after multiplying the first frequency domain sequence with a phase ramp signal without desired phase adjustment).

[0107] Figure 11 An example of the process is shown. Illustratively, processor 701 can execute specified instructions that cause a processor (e.g., processor 701 of the BBU, processor of the RU) to perform the process; note that some boxes may be optional. In 1101, the BBU (e.g., O-DU) can generate a RIM-RS frequency domain sequence. In 1102, the BBU can map the RIM-RS frequency domain sequence to determine resource elements (REs) used for transmitting the RIM-RS. Specifically, the BBU can map the RIM-RS frequency domain sequence to a second OFDM symbol 802. In the case of phase reset described above, the BBU can correlate the RIM-RS frequency domain sequence with phase compensation parameters (e.g., ... It is the desired phase adjustment, equal to The RIM-RS frequency domain sequence is obtained by multiplying the RIM-RS sequence to obtain a phase-compensated RIM-RS frequency domain sequence, and the phase-compensated RIM-RS frequency domain sequence is mapped to the second OFDM symbol 802. In 1103, the BBU can generate a phase ramp signal based on resource elements (e.g., subcarrier configuration) and the CP length of the second OFDM symbol 802. In an example with the phase reset described above, the BBU can generate a phase ramp signal such that the phase ramp signal can include a phase compensation parameter (e.g., φ is a phase compensation parameter, which can be equal to φ = 2πf0T). CP,2nd In 1104, the BBU can multiply the phase ramp signal with the RIM-RS frequency domain sequence to obtain a multiplication sequence. In one example with phase reset, the BBU can multiply the phase ramp signal including phase compensation parameters with the RIM-RS frequency domain sequence to obtain a multiplication sequence. In another example, the BBU can multiply the phase ramp signal without phase compensation parameters with a phase-compensated RIM-RS frequency domain sequence to obtain a multiplication sequence. In 1105, the BBU can map the multiplication sequence to a resource element. Specifically, the BBU can map the multiplication sequence to the first OFDM symbol 801. Therefore, the BBU can send information representing the RIM-RS frequency domain sequence and the multiplication sequence to the RU for transmitting RF signals corresponding to the RIM-RS frequency domain sequence and the multiplication sequence in two consecutive OFDM symbols (i.e., the first OFDM symbol 801 and the second OFDM symbol 802).

[0108] In 1106, the RU can receive information transmitted by the BBU and perform (1105) a lower PHY function using the received information. The lower PHY function may include performing an IDFT on the received RIM-RS frequency domain sequence and the multiplication sequence. The lower PHY function may also include adding a CP to each of the first OFDM symbol 801 and the second OFDM symbol, the added CP including the CP length. In the case of phase reset, the RU may also reset the phase of each OFDM symbol. In 1107, the RU can form the first OFDM symbol 801 and the second OFDM symbol into a consecutive OFDM symbol. The second OFDM symbol 802 may include a RIM-RS frequency domain sequence to which the IDFT is applied. The second OFDM symbol 802 may follow the first OFDM symbol 801 in the time domain, wherein the first OFDM symbol 801 may include a multiplication sequence to which the IDFT is applied.

[0109] Figure 12An exemplary radio access network architecture is illustrated, in which the radio access network is decomposed into multiple units. In LTE or 5G NR, a network access node (e.g., a BS) can implement the entire network stack, including the physical layer (PHY), media access control (MAC), radio link control (RLC), packet data convergence control (PDCP), and radio resource control (RRC) functions of the network stack. In a distributed approach to the radio access network, the processing of the network stack is decomposed into at least two units (e.g., RU, DU, and CU). While the example illustrates a distributed architecture based on an Open RAN (O-RAN) architecture, those skilled in the art can apply the teachings provided herein to other types of distributed architectures, such as a baseband unit (BBU) that can operate in the cloud and can be partitioned into control units (CUs) according to the 3GPP standard Rel.15.

[0110] In various deployments of recently emerging RAN architectures (e.g., Open Radio Access Network (O-RAN) architectures), network access nodes can have functionality partitioned across multiple units, aiming to meet the demand for increased capacity by providing a flexible and interoperable approach to the RAN. The exemplary RAN 1200 provided herein includes Radio Units (RUs) 1201, DUs 1202, Cues 1203, Near-RT-RICs 1204, and a Service Management and Coordination Framework (SMO) 1205 including a non-RT-RIC 1206. Those skilled in the art will recognize that the illustrated structures can represent logical architectures where one or more entities of a mobile communication network can be implemented by the same physical entity, or distributed physical entities (multiple devices operating collectively) can implement one of the entities of the mobile communication network provided herein.

[0111] Illustratively, the non-RT RIC 1206 can be configured to perform functions within the SMO that drive content carried across the A1 interface of the O-RAN architecture. This includes the non-RT RIC framework and non-RT RIC applications (rApps). The near-RT-RIC 1204 can be an O-RAN Network Function (NF) that enables near real-time control and optimization of RAN elements and resources via fine-grained data collection and actions through the E2 interface. It can include AI / ML (Artificial Intelligence / Machine Learning) workflows, including model training, inference, and updates. The CU 1203 can be an O-RAN CU, decomposed into O-CU-CP (a logical node hosting the control plane portion of the RRC and PDCP protocols) and O-CU-UP (a logical node hosting the user plane portion of the PDCP and SDAP protocols). The DU 1202 can be an O-DU, serving as a logical node hosting the RLC / MAC / high PHY layer based on lower-layer functional partitioning. The RU 1201 can be an O-RU, serving as a logical node hosting the low PHY layer and RF processing based on lower-layer functional partitioning. This is similar to 3GPP's "TRP" or "RRH", but more specifically includes the low PHY layer (FFT / iFFT, PRACH extraction).

[0112] There are many methods to provide partitioning among multiple units. In this illustrative example, CU 1203 (e.g., O-CU) may primarily be responsible for hosting non-real-time operations of Radio Resource Control (RRC), PDCP protocol, and Service Data Adaptation Protocol (SDAP). DU (e.g., O-DU) 1202 may primarily be responsible for hosting real-time operations such as RLC layer functions, MAC layer functions, and higher PHY functions. RU 1201 (e.g., O-RU) may primarily be responsible for hosting lower PHY functions to transmit and receive radio communication signals to / from terminal equipment (e.g., UE) and to provide data streams to DUs via fronthaul interfaces (e.g., open fronthaul). SMO 1205 may provide functions to manage areas such as RAN management, core management, and transport management, and non-RTRIC 1206 may provide functions to support intelligent RAN optimization via policy-based guidance, AI / ML model management, etc. The near-RT RIC 1204 can provide features for real-time optimization, including hosting one or more xApps that can collect real-time information (per UE or per cell) and provide services, and may also include AI / ML services.

[0113] For the sake of brevity, an exemplary RAN 1200 is illustrated. Those skilled in the art will recognize the aspects provided herein, and will also recognize that the exemplary RAN 1200 may include further features, such as the CUs being logically distributed into at least two entities (e.g., CU-control plane, CU-user plane), and various types of interfaces (e.g., E2, F1, O1, X2, NG-u, etc.) being present between the different entities of the exemplary RAN 1200.

[0114] According to the exemplary distributed RAN architecture, the UE can send and receive radio communication signals to and from RU 1201. The processing associated with the communication is performed at the appropriate layer of the network stack by the appropriate entity responsible for performing the corresponding function at the appropriate layer.

[0115] According to various aspects of this disclosure, DU 1202 and RU 1201 can be configured as described herein, and in particular, DU 1202 can include device 700. In other words, the device can be configured to perform the operations described in this disclosure for DU.

[0116] Figure 13 An example of the method is shown. The method may include: determining (1301) a first frequency domain sequence comprising a plurality of first frequency domain symbols for a Remote Interference Management Reference Signal (RIM-RS), wherein each of the plurality of first frequency domain symbols corresponds to a subcarrier among a plurality of subcarriers; determining (1302) a second frequency domain sequence comprising a plurality of second frequency domain symbols, wherein each of the plurality of second frequency domain symbols on a corresponding subcarrier among the plurality of subcarriers includes a phase-rotated version of a corresponding first frequency domain symbol on the corresponding subcarrier, wherein the phase-rotated version is phase-rotated based on the corresponding subcarrier and a cyclic prefix (CP) length; and instructing (1303) to transmit information representing the second frequency domain sequence and the first frequency domain sequence to a radio unit of a cellular network for transmission in consecutive orthogonal frequency division multiplexing (OFDM) symbols. A non-transitory computer-readable medium may include instructions that, if executed by a processor, cause the processor to perform the method.

[0117] The following examples relate to other aspects of this disclosure.

[0118] In Example 1, the subject matter includes an apparatus comprising: a memory; and a processor configured to: determine, for a Remote Interference Management Reference Signal (RIM-RS), a first frequency domain sequence comprising a plurality of first frequency domain symbols, wherein each of the plurality of first frequency domain symbols corresponds to a subcarrier among a plurality of subcarriers; determine, a second frequency domain sequence comprising a plurality of second frequency domain symbols, wherein each of the plurality of second frequency domain symbols on a corresponding subcarrier among the plurality of subcarriers includes a phase-rotated version of a corresponding first frequency domain symbol on the corresponding subcarrier, wherein the phase-rotated version is phase-rotated based on the corresponding subcarrier and a cyclic prefix (CP) length; and instruct to transmit information representing the second frequency domain sequence and the first frequency domain sequence to a radio unit of a cellular network for transmission in consecutive orthogonal frequency division multiplexing (OFDM) symbols.

[0119] In Example 2, the subject of Example 1 is repeated, where the phase rotation amount for each corresponding subcarrier increases linearly across multiple subcarriers.

[0120] In Example 3, the subject of Example 2 is repeated, where for every two consecutive subcarriers in a plurality of subcarriers, the phase rotation amount increases based on the CP length.

[0121] In Example 4, the subject of any of Examples 1 to 3 is used, where the CP length is the CP duration for the transmission of consecutive OFDM symbols.

[0122] In Example 5, the subject of any of Examples 1 to 4 is that consecutive OFDM symbols are scheduled for transmission within a single time slot.

[0123] In Example 6, the subject of any one of Examples 1 to 5 is provided, wherein the processor is further configured to: generate a first frequency domain sequence; and for a RIM-RS transmission, determine a resource element comprising consecutive OFDM symbols, the consecutive OFDM symbols comprising a first OFDM symbol followed by a second OFDM symbol based on the first frequency domain sequence; wherein the CP length is associated with the second OFDM symbol.

[0124] In Example 7, the subject of Example 6 is repeated, where the first OFDM symbol is scheduled for transmission in the first time slot, and the second OFDM symbol is scheduled for transmission in the second time slot following the first time slot.

[0125] In Example 8, the subject of Example 6 or Example 7, the processor is further configured to: generate a phase ramp signal based on the CP length and multiple subcarriers; and multiply the phase ramp signal by a first frequency domain sequence to obtain a second frequency domain sequence.

[0126] In Example 9, the topic of Example 8 is revisited, where the phase ramp signal is based on the mathematical equation exp(-j·2π·n·SCS·T).CP,2nd The function is generated as follows: n includes integer subcarrier indices of multiple subcarriers, each integer subcarrier index corresponding to a corresponding subcarrier among the multiple subcarriers; SCS includes the subcarrier spacing of the multiple subcarriers; T... CP,2nd This includes the time length of the CP (Content Length) component.

[0127] In Example 10, the topic of Example 8 is discussed, where the phase ramp signal is based on the mathematical equation exp(-j·2π·n·N). CP,2nd / N FFT The function is generated as follows: n ∈ N, where n includes integer subcarrier indices, each integer subcarrier index corresponding to a specific subcarrier among the multiple subcarriers. CP,2nd Includes the number of integer samples, N, representing the duration of the CP length. FFT This includes integers representing the number of multiple first frequency domain symbols.

[0128] In Example 11, the subject of any one of Examples 6 to 10, wherein the processor is further configured to: schedule a first transmission of the second frequency domain sequence within a first OFDM symbol; schedule a second transmission of the first frequency domain sequence within a second OFDM symbol; and encode information representing the scheduling of the first and second transmissions for transmission to a radio unit.

[0129] In Example 12, the subject of any of Examples 6 to 11, wherein the first frequency domain sequence and the second frequency domain sequence are configured such that when the same CP length is applied to the first OFDM symbol and the second OFDM symbol at the radio unit, the first OFDM symbol is a cyclically shifted version of the second OFDM symbol.

[0130] In Example 13, the subject matter of any one of Examples 1 to 12 may further include: a transmitter configured to transmit communication signals to a radio unit.

[0131] In Example 14, the subject of any one of Examples 1 to 13 is provided, wherein the cellular network includes an Open Radio Access Network (O-RAN); wherein the radio unit includes an O-RAN radio unit (O-RU) communicatively coupled to the device via a fronthaul interface; and wherein the device is used for an O-RAN distributed unit (O-DU).

[0132] In Example 15, the subject matter includes an apparatus comprising: a memory; and a processor configured to: generate a first frequency domain sequence for a Remote Interference Management Reference Signal (RIM-RS); generate a phase ramp signal based on a cyclic prefix (CP) length associated with a transmission of a radio unit in a cellular network; multiply the phase ramp signal by the first frequency domain sequence to obtain a second frequency domain sequence; and map the first and second frequency domain sequences to consecutive first and second OFDM symbols.

[0133] In Example 16, the subject of Example 15 is used, where the CP length is the CP duration for the transmission of consecutive OFDM symbols.

[0134] In Example 17, the subject of Example 15 or 16, the phase ramp signal is based on the mathematical equation exp(-j·2π·n·SCS·T) CP,2nd The function is generated as follows: n includes integer subcarrier indices of multiple subcarriers, each integer subcarrier index corresponding to a corresponding subcarrier among the multiple subcarriers; SCS includes the subcarrier spacing of the multiple subcarriers; T... CP,2nd This includes the time length of the CP (Content Length) component.

[0135] In Example 18, the subject of Example 15 or 16, the phase ramp signal is based on the mathematical equation exp(-j·2π·n·N). CP,2nd / N FFT The function is generated as follows: n ∈ N, where n includes integer subcarrier indices, each integer subcarrier index corresponding to a specific subcarrier among the multiple subcarriers. CP,2nd Includes the number of integer samples, N, representing the duration of the CP length. FFT This includes integers representing the number of multiple first frequency domain symbols.

[0136] In Example 19, a non-transitory computer-readable medium includes one or more instructions that, if executed by a processor, cause the processor to perform the following operations: determine a first frequency domain sequence comprising a plurality of first frequency domain symbols for a Remote Interference Management Reference Signal (RIM-RS), wherein each of the plurality of first frequency domain symbols corresponds to a subcarrier among a plurality of subcarriers; determine a second frequency domain sequence comprising a plurality of second frequency domain symbols, wherein each of the plurality of second frequency domain symbols on a corresponding subcarrier among the plurality of subcarriers includes a phase-rotated version of a corresponding first frequency domain symbol on the corresponding subcarrier, wherein the phase-rotated version is phase-rotated based on the corresponding subcarrier and a cyclic prefix (CP) length; and instruct to transmit information representing the second frequency domain sequence and the first frequency domain sequence to a radio unit of a cellular network for transmission in consecutive orthogonal frequency division multiplexing (OFDM) symbols.

[0137] In Example 20, the non-transitory computer-readable medium of Example 19 is used, wherein the phase rotation amount of each corresponding subcarrier increases linearly over multiple subcarriers.

[0138] In Example 21, a non-transitory computer-readable medium includes one or more instructions that, if executed by a processor, cause the processor to perform any one or any combination of the operations provided in this disclosure.

[0139] In Example 22, a method includes: determining a first frequency domain sequence comprising a plurality of first frequency domain symbols for a Remote Interference Management Reference Signal (RIM-RS), wherein each of the plurality of first frequency domain symbols corresponds to a subcarrier among a plurality of subcarriers; determining a second frequency domain sequence comprising a plurality of second frequency domain symbols, wherein each of the plurality of second frequency domain symbols on a corresponding subcarrier among the plurality of subcarriers includes a phase-rotated version of a corresponding first frequency domain symbol on the corresponding subcarrier, wherein the phase-rotated version is phase-rotated based on the corresponding subcarrier and a cyclic prefix (CP) length; and instructing a radio unit of a cellular network to transmit information representing the second frequency domain sequence and the first frequency domain sequence for transmission in consecutive orthogonal frequency division multiplexing (OFDM) symbols.

[0140] In Example 23, the method of Example 22 is used, wherein the method further includes any one or any combination of the operations provided in this disclosure.

[0141] The term “exemplary” is used herein to mean “as an example, instance, or illustration.” Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or superior to other embodiments or designs.

[0142] The words “multiple” and “many” in the specification or claims explicitly refer to a quantity greater than one. The terms “group,” “set,” “cluster,” “series,” “sequence,” “grouping,” etc., in the specification or claims refer to a quantity equal to or greater than one, i.e., one or more. Any term expressed in plural form without explicitly stating “multiple” or “many” also refers to a quantity equal to or greater than one.

[0143] As used herein, “memory” is understood to be a non-transitory computer-readable medium in which data or information can be stored for retrieval. References to “memory” herein are therefore understood to refer to volatile or non-volatile memory, including random access memory (“RAM”), read-only memory (“ROM”), flash memory, solid-state storage devices, magnetic tape, hard disk drives, optical drives, etc., or any combination thereof. Furthermore, registers, shift registers, processor registers, data buffers, etc., are also included in the term memory herein. A single component referred to as “memory” or “a memory” may consist of more than one memory of different types and therefore may refer to a collective component including one or more types of memory. Any single memory component may be separated into multiple generally equivalent memory components, and vice versa. Furthermore, while memory may be depicted as separate from one or more other components (as shown in the figures), memory may also be integrated with other components, for example, integrated on a common integrated chip or on a controller with embedded memory.

[0144] The term "software" refers to any type of executable instructions, including firmware.

[0145] In the context of this disclosure, the term "process" may be used, for example, to denote a method. Illustratively, any process described herein may be implemented as a method (e.g., a channel estimation process may be understood as a channel estimation method). Any process described herein may be implemented as a non-transitory computer-readable medium, including instructions that, when executed, are configured to cause one or more processors to perform the process (e.g., perform the method).

[0146] Throughout the accompanying drawings, it should be noted that similar reference numerals are used to depict the same or similar elements, features, and structures, unless otherwise specified. It should be noted that certain components may be omitted for simplicity. It should be noted that nodes (points) are provided to identify intersections of circuit lines in drawings that include electronic circuit diagrams.

[0147] The phrases “at least one” and “one or more” can be understood to include numerical quantities greater than or equal to one (e.g., one, two, three, four, [...] etc.). The phrase “at least one of…” relating to a group of elements can be used herein to indicate at least one element from a group of these elements. For example, the phrase “at least one” relating to a group of elements can be used herein to indicate a selection of: one of the listed elements, one of several listed elements, several individual listed elements, or several of several individual listed elements.

[0148] The terms “multiple” and “more” in the specification and claims explicitly refer to a quantity greater than one. Therefore, any phrase explicitly referring to the quantity of elements (e.g., “multiple (elements)”, “more (elements)”) explicitly refers to more than one of the stated elements. For example, the phrase “multiple” can be understood to include numerical quantities greater than or equal to two (e.g., two, three, four, five, [...] etc.).

[0149] As used herein, a signal or information that “indicates,” “represents,” “represents,” or “indicates” a value or other information can be a digital or analog signal encoded or otherwise transmitted in a manner that can be decoded by a component receiving the signal and / or cause a responsive action in that component. The signal may be stored or buffered in a computer-readable storage medium before being received by a receiving component, and the receiving component may retrieve the signal from the storage medium. Furthermore, a “value” that “indicates” or “represents” a quantity, state, or parameter may be physically embodied as a digital signal, analog signal, or stored bits that encode or otherwise transmit that value.

[0150] As used herein, signals can be transmitted or conducted through signal chains, where they are processed to alter their characteristics, such as phase, amplitude, and frequency. A signal can be referred to as the same signal even if these characteristics are modified. Generally, a signal can be considered the same signal as long as it continues to encode the same information. For example, a transmitted signal can be considered to refer to baseband, intermediate frequency, and radio frequency transmitted signals.

[0151] As used herein, the terms "processor" or "controller" can be understood as any kind of technical entity that allows the manipulation of data. Data can be manipulated according to one or more specific functions performed by the processor. Additionally, the processor or controller used herein can be understood as any kind of circuit, such as any kind of analog or digital circuit. A processor or controller can therefore be or may include analog circuits, digital circuits, mixed-signal circuits, logic circuits, processors, microprocessors, central processing units (CPUs), graphics processing units (GPUs), digital signal processors (DSPs), field-programmable gate arrays (FPGAs), integrated circuits, application-specific integrated circuits (ASICs), etc., or any combination thereof. Any other kind of implementation of the various functions described in more detail below can also be understood as a processor, controller, or logic circuit. It will be understood that any two (or more) of the processors, controllers, or logic circuits detailed herein can be implemented as a single entity with equivalent functionality, and conversely, any single processor, controller, or logic circuit detailed herein can be implemented as two (or more) separate entities with equivalent functionality.

[0152] The term "one or more processors" is intended to refer to either a processor or a controller. One or more processors may include one or more processors. These terms are used only as alternatives to "processor" or "controller".

[0153] As used herein, the terms “module,” “component,” “system,” “circuit,” “element,” “slice,” and “circuit” are intended to refer to a group or group of one or more electronic components, computer-related entities, hardware, software (e.g., in execution), and / or firmware. For example, a circuit or similar term can be a processor, a process running on a processor, a controller, an object, an executable program, a storage device, and / or a computer having processing capabilities. For illustration, an application running on a server and a server itself can also be a circuit. One or more circuits may reside within the same circuit, and circuits may be localized within a computer and / or distributed across two or more computers. This document may describe a group of elements or a group of other circuits, wherein the term “group” may be interpreted as “one or more.”

[0154] For Radio Units (RU), Distributed Units (DU), and Centralized Units (CU), the terminology according to the Open Wide Area Network (O-RAN) specification will be considered. Essentially, a base station is considered to be decomposed into these units according to layers of the corresponding protocol stack decomposed to these logical nodes. All these units can be implemented by the same device or multiple devices, where each device can deploy one of these units.

[0155] As used herein, the term "data" can be understood to include information in any suitable analog or digital form, such as being provided as a file, a portion of a file, a set of files, a signal or stream, a portion of a signal or stream, a set of signals or streams, etc. Additionally, the term "data" can also be used to refer to information, for example, in the form of a pointer. However, the term "data" is not limited to the examples above and can take various forms and represent any information understood in the art. The term "data item" can include data or a portion of data.

[0156] It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be physically connected or coupled to that other element, allowing current and / or electromagnetic radiation (e.g., signals) to flow along the conductive path formed by these elements. Essentially, such an element can be connected or coupled to another element. When these elements are described as being coupled or connected to each other, an intermediate conductive, inductive, or capacitive element may be present between the element and the other element. Additionally, when coupled or connected to each other, one element may be able to induce the flow of voltage or current, or the propagation of electromagnetic waves, in the other element without physical contact or an intermediate component. Furthermore, when a voltage, current, or signal is referred to as being "provided" to an element, that voltage, current, or signal can be conducted to the element through a physical connection or through capacitive coupling, electromagnetic coupling, or inductive coupling that does not involve a physical connection.

[0157] Unless explicitly stated otherwise, the term “transmit” encompasses both direct transmission (point-to-point) and indirect transmission (via one or more intermediate points). Similarly, the term “receive” encompasses both direct and indirect reception. Furthermore, the terms “transmit,” “receive,” “transmit,” and other similar terms encompass both physical transmission (e.g., transmission of radio signals) and logical transmission (e.g., transmission of digital data via a logical software-level connection). For example, a processor or controller may transmit or receive data in the form of radio signals with another processor or controller via a software-level connection, where physical transmission and reception are handled by radio layer components such as RF transceivers and antennas, and logical transmission and reception via a software-level connection are performed by the processor or controller. The term “transmit” encompasses one or both of transmission and reception, i.e., one-way or two-way communication in one or both of the incoming and outgoing directions. The term “computation” encompasses both “direct” computation via mathematical expressions / formulas / relationships and “indirect” computation via lookups or hash tables and other array indexing or search operations.

[0158] While the above description and related figures depict electronic device components as individual elements, those skilled in the art will understand the various possibilities of combining or integrating discrete elements into a single element. This can include combining two or more circuits to form a single circuit, mounting two or more circuits onto a common chip or rack to form an integrated element, executing discrete software components on a common processor core, and so on. Conversely, those skilled in the art will understand the possibility of separating a single element into two or more discrete elements, such as dividing a single circuit into two or more separate circuits, separating a chip or rack into discrete elements originally provided thereon, separating a software component into two or more parts and executing each part on a separate processor core, and so on.

[0159] It will be understood that the implementation of the methods detailed herein is illustrative in nature and is therefore to be understood as being implementable in a corresponding device. Similarly, it will be understood that the implementation of the devices detailed herein is to be understood as being implementable as the corresponding methods. Therefore, it will be understood that a device corresponding to the methods detailed herein may include one or more components configured to perform each aspect of the relevant methods. All abbreviations defined in the foregoing description are valid within all claims included herein.

Claims

1. An apparatus comprising: Memory; And a processor, which is configured as follows: For the Remote Interference Management Reference Signal (RIM-RS), a first frequency domain sequence comprising a plurality of first frequency domain symbols is determined, wherein each of the plurality of first frequency domain symbols corresponds to a subcarrier among a plurality of subcarriers; Determine a second frequency domain sequence comprising a plurality of second frequency domain symbols, wherein each of the plurality of second frequency domain symbols on a corresponding subcarrier comprises a phase-rotated version of a corresponding first frequency domain symbol on the corresponding subcarrier, wherein the phase-rotated version is phase-rotated based on the corresponding subcarrier and the cyclic prefix (CP) length; and The instruction is to send information representing the second frequency domain sequence and the first frequency domain sequence to the radio unit of the cellular network for transmission in consecutive orthogonal frequency division multiplexing (OFDM) symbols.

2. The apparatus according to claim 1, wherein, The phase rotation of each corresponding subcarrier increases linearly over the plurality of subcarriers.

3. The apparatus according to claim 2, wherein, For every two consecutive subcarriers among the plurality of subcarriers, the phase rotation amount increases based on the CP length.

4. The apparatus according to claim 1, wherein, The CP length is the CP duration used for the transmission of the continuous OFDM symbols.

5. The apparatus according to claim 1, wherein, The consecutive OFDM symbols are scheduled for transmission within a single time slot.

6. The apparatus according to any one of claims 1 to 5, wherein, The processor is also configured to: Generate the first frequency domain sequence; and For the RIM-RS transmission, a resource element comprising the consecutive OFDM symbols is determined, the consecutive OFDM symbols comprising a first OFDM symbol followed by a second OFDM symbol based on the first frequency domain sequence, wherein the CP length is associated with the second OFDM symbol.

7. The apparatus according to claim 6, wherein, The first OFDM symbol is scheduled for transmission in the first time slot, and the second OFDM symbol is scheduled for transmission in the second time slot following the first time slot.

8. The apparatus according to claim 6, wherein, The processor is also configured to: Schedule the first transmission of the second frequency domain sequence within the first OFDM symbol; Schedule the second transmission of the first frequency domain sequence within the second OFDM symbol; and Information representing the scheduling of the first and second transmissions is encoded and transmitted to the radio unit.

9. The apparatus according to claim 6, wherein, The first frequency domain sequence and the second frequency domain sequence are configured such that when the same CP length is applied to the first OFDM symbol and the second OFDM symbol at the radio unit, the first OFDM symbol is a cyclically shifted version of the second OFDM symbol.

10. The apparatus according to claim 6, wherein, The processor is also configured to: A phase ramp signal is generated based on the CP length and the plurality of subcarriers; and The phase ramp signal is multiplied by the first frequency domain sequence to obtain the second frequency domain sequence.

11. The apparatus according to claim 10, wherein, The phase ramp signal is based on the mathematical equation exp(-j·2π·n·SCS·T). CP,2nd The process is generated as follows: n includes integer subcarrier indices of the plurality of subcarriers, each integer subcarrier index corresponding to a corresponding subcarrier among the plurality of subcarriers; SCS includes the subcarrier spacing of the plurality of subcarriers; T... CP,2nd The time length including the CP length.

12. The apparatus according to claim 10, wherein, The phase ramp signal is based on the mathematical equation exp(-j·2π·n·N). CP,2nd / N FFT The process is generated as follows: n includes integer subcarrier indices of the plurality of subcarriers, each integer subcarrier index corresponding to a corresponding subcarrier among the plurality of subcarriers, N... CP,2nd Including the integer number of samples, N, representing the duration of the CP length. FFT Including an integer representing the number of the plurality of first frequency domain symbols.

13. The apparatus according to any one of claims 1 to 5, wherein, The processor is also configured to apply phase compensation to compensate for phase reset at the radio unit.

14. The apparatus according to any one of claims 1 to 5, wherein, The cellular network includes an Open Radio Access Network (O-RAN); The radio unit includes an O-RAN radio unit (O-RU) communicatively coupled to the device via a fronthaul interface; and The device is used in O-RAN distributed units (O-DU).

15. An apparatus comprising: Memory; And a processor, which is configured as follows: A first frequency domain sequence is generated for the Remote Interference Management Reference Signal (RIM-RS); A phase ramp signal is generated based on the cyclic prefix (CP) length associated with the transmission of radio units in the cellular network; Multiply the phase ramp signal by the first frequency domain sequence to obtain the second frequency domain sequence; and The first frequency domain sequence and the second frequency domain sequence are mapped to consecutive first orthogonal frequency division multiplexing (OFDM) symbols and second OFDM symbols.

16. The apparatus according to claim 15, wherein, The CP length is the duration of the CP used for the transmission of continuous OFDM symbols.

17. The apparatus according to claim 15, wherein, The phase ramp signal is based on the mathematical equation exp(-j·2π·n·SCS·T). CP,2nd The process is generated as follows: n includes integer subcarrier indices of the plurality of subcarriers, each integer subcarrier index corresponding to a corresponding subcarrier among the plurality of subcarriers; SCS includes the subcarrier spacing of the plurality of subcarriers; T... CP,2nd The time length including the CP length.

18. The apparatus according to claim 15, wherein, The phase ramp signal is based on the mathematical equation exp(-j·2π·n·N). CP,2nd / N FFT The process is generated as follows: n includes integer subcarrier indices of the plurality of subcarriers, each integer subcarrier index corresponding to a corresponding subcarrier among the plurality of subcarriers, N... CP,2nd Including the integer number of samples, N, representing the duration of the CP length. FFT Including an integer representing the number of the plurality of first frequency domain symbols.

19. A non-transitory computer-readable medium comprising one or more instructions, which, if executed by a processor, cause the processor to perform the following operations: For the Remote Interference Management Reference Signal (RIM-RS), a first frequency domain sequence comprising multiple first frequency domain symbols is determined, wherein, Each of the plurality of first frequency domain symbols corresponds to a subcarrier in the plurality of subcarriers; Determine a second frequency domain sequence comprising a plurality of second frequency domain symbols, wherein each of the plurality of second frequency domain symbols on a corresponding subcarrier comprises a phase-rotated version of a corresponding first frequency domain symbol on the corresponding subcarrier, wherein the phase-rotated version is phase-rotated based on the corresponding subcarrier and the cyclic prefix (CP) length; and The instruction is to send information representing the second frequency domain sequence and the first frequency domain sequence to the radio unit of the cellular network for transmission in consecutive orthogonal frequency division multiplexing (OFDM) symbols.

20. The non-transitory computer-readable medium according to claim 19, wherein, The phase rotation of each corresponding subcarrier increases linearly over the plurality of subcarriers.

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