Method for performing time synchronization of base station signals in distributed antenna system

Abstract

According to one aspect of the technical idea of the present disclosure, a method performed by a communication node communicatively connected to at least one lower communication node in a communication system is disclosed, the method comprising the steps of: receiving a first signal from an open-radio access network (O-RAN) base station; receiving a second signal from a legacy base station; determining a delay control value on the basis of a predetermined timing parameter value for the first signal and a sum delay value of the communication system; and delay-compensating the first signal on the basis of the delay control value so that the first signal is synchronized with the second signal at a reference transmission time.

Description

Method for performing time synchronization of base station signals in a distributed antenna system

[0001] The present disclosure relates to a distributed antenna system, and more particularly, to a method for performing time synchronization for an O-RAN base station signal and a legacy base station signal in a distributed antenna system.

[0002]

[0003] A Distributed Antenna System (DAS) is a communications system designed to relay a mobile service provider's macro wireless service signals. It consists of a common node (e.g., a headend unit) and spatially separated antenna nodes (e.g., remote units) connected to the common node. DAS is installed in areas with poor radio reception, such as inside buildings, basements, subways, tunnels, apartment complexes in residential areas, and stadiums, to extend the coverage of base stations.

[0004] O-RAN (Open-Radio Access Network) is a radio access network based on NR (New Radio) technology, a fifth-generation mobile communication standard established by 3GPP (3rd Generation Partnership Project). It provides an open fronthaul interface standard for interworking between O-DU (O-RAN Distributed Unit) and O-RU (O-RAN Radio Unit) manufactured by different manufacturers.

[0005] While DAS can support O-RAN base stations, because DAS is outside the scope of the O-RAN standard, there is no signal processing method defined for supporting O-RAN base stations, which may cause service issues. In particular, in a TDD (Time Division Duplex) environment where DAS simultaneously supports O-RAN and legacy base stations, if proper signal synchronization is not achieved that takes into account the different signal processing characteristics of the two base stations, interference between the signals of the two base stations may occur, significantly degrading communication quality.

[0006] Therefore, an effective synchronization method for base station signals is required in a DAS environment that simultaneously supports O-RAN base stations and legacy base stations.

[0007]

[0008] The technical challenge that the technical idea of ​​the present disclosure seeks to achieve is to propose a method for performing time synchronization of base station signals in a distributed antenna system supporting O-RAN base stations and legacy base stations.

[0009] The technical task to be achieved by the technical idea of ​​the present disclosure is not limited to the task(s) mentioned above, and other task(s) not mentioned will be clearly understood by those skilled in the art from the description below.

[0010]

[0011] According to one aspect of the technical idea of ​​the present disclosure, a method is disclosed, performed by a communication node communicatively connected to at least one lower communication node in a communication system, the method comprising: receiving a first signal from an Open-Radio Access Network (O-RAN) base station; receiving a second signal from a legacy base station; determining a delay control value based on a predetermined timing parameter value for the first signal and a sum delay value of the communication system; and delay compensating the first signal based on the delay control value such that the first signal is synchronized with the second signal at a reference transmission time.

[0012] In one embodiment, the step of determining the delay control value may include the step of calculating a difference between the timing parameter value and the sum delay value to determine the delay control value.

[0013] In one embodiment, the method may further include a step of delay compensating the second signal based on the sum delay value.

[0014] In one embodiment, the timing parameter value may be a value that is predetermined based on a reception window range of the O-RAN base station, the reference transmission time, and a processing delay for the first signal at the communication node.

[0015] In one embodiment, the combined delay value may include a transmission delay value between the communication node and the lower communication node, and a processing delay value at the lower communication node.

[0016] In one embodiment, the communication system may be a distributed antenna system, the communication node may be a main unit of the distributed antenna system, and the subordinate communication node may be a remote unit of the distributed antenna system.

[0017] In one embodiment, the first and second signals may be signals that comply with the enhanced Common Public Radio Interface (eCPRI) standard.

[0018] In one embodiment, the communication node and the subordinate communication node may be connected through a CPRI-based interface.

[0019] According to another aspect of the technical idea of ​​the present disclosure, a communication node is disclosed, which is communicatively connected to at least one lower-level communication node in a communication system, the communication node comprising: a memory; a transceiver for receiving a first signal from an Open-Radio Access Network (O-RAN) base station and a second signal from a legacy base station, and transmitting the first and second signals to the lower-level node; and at least one processor operatively connected to the memory and the transceiver; wherein the memory stores instructions that, when executed, cause the at least one processor to determine a delay control value based on a predetermined timing parameter value for the first signal and a sum delay value of the communication system, and to delay compensate the first signal based on the delay control value such that the first signal is synchronized with the second signal at a reference transmission time.

[0020]

[0021] According to embodiments of the present disclosure, in a DAS environment supporting an O-RAN base station and a legacy base station, through a delay control mechanism that comprehensively considers the timing advance characteristics of an O-RAN base station signal and the maximum delay criterion compensation characteristics of a legacy base station signal, interference between base station signals in a TDD scheme can be minimized and communication quality can be improved by effectively synchronizing different base station signals.

[0022] Accordingly, it is possible to support next-generation network technologies such as O-RAN while utilizing existing DAS infrastructure, reducing operators' infrastructure investment costs and providing flexibility in network evolution.

[0023] Additionally, it can provide consistent time synchronization even in environments where equipment from various manufacturers is mixed, thereby improving interoperability in multi-vendor environments.

[0024] The effects that can be obtained by embodiments according to the technical idea of ​​the present disclosure are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the technical idea of ​​the present disclosure belongs from the description below.

[0025]

[0026] To more fully understand the drawings cited in this disclosure, a brief description of each drawing is provided.

[0027] FIG. 1 is a block diagram of a communication system according to one embodiment of the present disclosure.

[0028] Figure 2 is a diagram for explaining a delay processing method of an O-RAN base station.

[0029] FIG. 3 is a diagram for explaining a method for performing downlink delay compensation in a communication system according to one embodiment of the present disclosure.

[0030] FIG. 4 is a diagram for explaining a method for performing delay compensation of an uplink in a communication system according to one embodiment of the present disclosure.

[0031] FIG. 5 is a block diagram schematically illustrating the structure of a communication system according to one embodiment of the present disclosure.

[0032] FIG. 6 is a schematic diagram illustrating the configuration of a main unit according to one embodiment of the present disclosure.

[0033] FIG. 7 is a schematic diagram illustrating the configuration of a hub unit according to one embodiment of the present disclosure.

[0034] FIG. 8 is a schematic diagram illustrating the configuration of a remote unit according to one embodiment of the present disclosure.

[0035]

[0036] The technical concept of the present disclosure is susceptible to various modifications and various embodiments. Specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the technical concept of the present disclosure to specific embodiments, and it should be understood that all modifications, equivalents, and alternatives fall within the scope of the technical concept of the present disclosure.

[0037] The terms used in this disclosure are used only to describe specific embodiments and may not be intended to limit the scope of other embodiments. The singular expression may include plural expressions unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by those of ordinary skill in the art described in this disclosure. Terms defined in general dictionaries among the terms used in this disclosure may be interpreted as having the same or similar meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined in this disclosure. In some cases, even if a term is defined in this disclosure, it cannot be interpreted to exclude embodiments of the present disclosure.

[0038] The various embodiments of the present disclosure described below primarily illustrate hardware-based approaches. However, since the various embodiments of the present disclosure include techniques utilizing both hardware and software, the various embodiments of the present disclosure do not exclude software-based approaches.

[0039] The various illustrative logical blocks / sections, modules, and circuits described in connection with the present disclosure, processors, may be implemented or performed by a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented by a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0040] In the following description, terms referring to signals (e.g., message, information, preamble, signal, signaling, sequence, stream), terms referring to resources (e.g., symbol, slot, subframe, radio frame, subcarrier, resource element (RE), resource block (RB), bandwidth part (BWP), occasion), terms for operational states (e.g., step, operation, procedure), terms referring to data (e.g., packet, user stream, information, bit, symbol, codeword), terms referring to channels, terms referring to control information (e.g., downlink control information (DCI), medium access control element (MAC CE), radio resource control (RRC) signaling), terms referring to network entities, terms referring to components of devices, etc. are examples for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may be used.

[0041] Additionally, in the present disclosure, expressions such as "more than" or "less than" may be used to determine whether a specific condition is satisfied or fulfilled. However, this is merely a description for expressing an example and does not exclude descriptions of "more than" or "less than." Conditions described as "more than" may be replaced with "more than," conditions described as "less than" may be replaced with "less than," and conditions described as "more than and less than" may be replaced with "more than and less than."

[0042] Additionally, although the present disclosure describes various embodiments using terms used in some communication standards (e.g., 3rd Generation Partnership Project (3GPP), extensible radio access network (xRAN), open-radio access network (O-RAN), etc.), these are merely examples for illustrative purposes.

[0043] In the present disclosure, a base station is an entity that performs resource allocation of a terminal, and may be at least one of a Node B, a BS (Base Station), an eNB (eNode B), a gNB (gNode B), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function.

[0044] Existing distributed antenna systems (DAS) are designed to either establish dedicated facilities between operators or operate remote units (RUs) only for base stations with the same architecture (O-RAN or legacy base stations). In other words, a single DAS environment typically consists of separate systems that utilize only base stations that adhere to O-RAN standards or only legacy base stations. In this case, a single control algorithm tailored to each system enables delay compensation and timing synchronization between RUs.

[0045] However, when simultaneously supporting O-RAN and legacy base stations via DAS, issues may arise due to the different delay handling characteristics of the two base stations. O-RAN base stations define terminal-to-terminal delay standards based on delay profiles and utilize timing advance methods, whereas legacy base stations based on the Common Public Radio Interface (CPRI) utilize a compensation method based on maximum delay. Because DAS typically applies the same delay compensation method as legacy base stations, synchronization issues may arise when relaying signals from both O-RAN and legacy base stations through the same remote unit (RU) of the DAS.

[0046] To address these issues, various aspects of the present disclosure propose techniques for performing consistent time synchronization by comprehensively considering each delay control algorithm when O-RAN base stations and legacy base stations are mixed in a DAS environment.

[0047] Hereinafter, various embodiments according to the technical idea of ​​the present disclosure will be described in detail.

[0048]

[0049] FIG. 1 is a block diagram of a communication system according to one embodiment of the present disclosure.

[0050] The communication system may include an O-RAN base station (105), a legacy base station (110), a radio interface unit (RIU) (115), a main unit (MU) (120), a hub unit (HU) (125), and a remote unit (RU) (130).

[0051] Here, RIU (115), MU (120), HU (125), and RU (130) can constitute a distributed antenna system. In Fig. 1, for convenience of explanation, an embodiment is illustrated in which the distributed antenna system includes one RIU (115), one MU (120), one HU (125), and one RU (130) each, and the corresponding node units are connected in a cascade structure. However, the present invention is not limited thereto, and the number and connection structure of each node unit constituting the distributed antenna system can be variously modified. For example, a plurality of RUs (130) may be configured and connected to the HU (125) in a cascade and / or star structure. As another example, a plurality of HUs (125) may be configured and a plurality of RUs may be connected to each HU in a cascade and / or star structure. As another example, MU (120) may be configured in multiple units, and each MU may have multiple HUs and RUs connected in a cascade and / or star structure. Meanwhile, O-RAN base station (105), legacy base station (110), RIU (115), MU (120), HU (125), and RU (130) may be wiredly connected to upper and / or lower units through a predetermined transmission medium (e.g., optical cable, copper wire, etc.).

[0052] The O-RAN base station (105) may include an O-RAN distributed unit (O-DU) and an O-RAN radio unit (O-RU) (not shown) connected via an open fronthaul interface based on eCPRI defined in the O-RAN standard. In FIG. 1, only the O-DU is shown as a representative configuration of the O-RAN base station (105), but it is obvious that various entities defined in the O-RAN standard, such as an MSE, a Centralized unit (CU), and a RAN intelligent controller (RIC), may be further included in the O-RAN base station (105).

[0053] In one embodiment, the O-RAN base station (105) may be the O-DU, and the O-DU may be communicatively connected to the MU (120). That is, the distributed antenna system may have a structure in which the O-DU is linked to the O-RU instead of the O-RU, and the O-RAN base station (105) may transmit a signal conforming to the eCPRI standard to a terminal located within the coverage of the distributed antenna system through the distributed antenna system, thereby providing various wireless services, such as 5G NR, to the terminal.

[0054] A legacy base station (110) may include a digital unit (DU) and a radio unit (RU) connected via a CPRI-based fronthaul interface. The DU may be referred to as a baseband unit (BBU), and the RU may be referred to as a remote radio unit (RRU), a remote radio head (RRH), or the like.

[0055] In one embodiment, the legacy base station (110) may be the RRH, and the RRH may be communicatively connected to the MU (120) via the RIU (115). In this case, a wireless signal output from the RRH may be converted into a digital signal conforming to a predetermined digital interface standard, for example, the eCPRI standard, via the RIU (115) and transmitted to the MU (120).

[0056] RIU (115) may be a device for interfacing between a legacy base station (110) and an MU (120). RIU (115) may convert a signal output from the legacy base station (110) into a signal format required by the MU (120).

[0057] For example, the RIU (115) may convert and output an analog wireless signal input from a legacy base station (110), i.e., the RRH, into an Ethernet signal of the eCPRI standard required by the MU (120) to support integration with the signal of the O-RAN base station (105). In this case, the RIU (115) may include an Analog-Digital Converter (ADC) (115a) for converting the analog wireless signal input from the RRH into a digital signal, a Digital Down Sampling (DDS) (115b) for a predetermined digital processing such as digital down sampling, and an Ethernet transceiver (Ethernet) (115c) for transmitting and receiving an Ethernet-based digital signal. It may take about 1 usec (microsecond) for the RIU (115) to receive an analog wireless signal and transmit an eCPRI-based digital signal to the MU (120).

[0058] Meanwhile, depending on the embodiment, RIU (115) may not be implemented as a separate unit from MU (120), but may be included in MU (120).

[0059] The MU (120), HU (125), and RU (130), which correspond to the headend node, extension node, and remote node of the above-described distributed antenna system, will be described in more detail.

[0060] The MU (120) may include an Ethernet transceiver (120a) for transmitting and receiving signals with an O-RAN base station (105), and an Ethernet transceiver (120b) for transmitting and receiving signals with a legacy base station (110) via an RIU (115).

[0061] When the MU (120) receives a signal from the O-RAN base station (105), it can process the received signal through the eCPRI and LowPHY function (120c). For example, the MU (120) can perform processing such as packet header processing, synchronization information extraction, data packet analysis, FFT / IFFT, precoding, resource mapping, etc. through the eCPRI and LowPHY function (120c), and can convert the received signal into a form suitable for processing in lower nodes. The time required for the MU (120) to receive a signal and process the signal through the eCPRI and LowPHY function (120c) may be approximately 30 usec (140).

[0062] When MU (120) receives a signal from a legacy base station (110) through RIU (115), it can perform an operation of copying the signal in order to transmit it to HU (125) and RU (130). When performing the copying operation, it may take about 0.5 usec (145).

[0063] The MU (120) may convert a signal received from an O-RAN base station (105) and a signal received from a legacy base station (110) via an RIU (115) into a signal conforming to the CPRI standard (CPRI REC (120d, 120e)) after a predetermined process (e.g., digital processing to make it suitable for processing within the distributed antenna system), and transmit the signal to the HU (125). In this way, the time required to transmit a signal from the MU (120) to the HU (125) via the CPRI interface may be approximately 2 usec.

[0064] When HU (125) receives a signal from MU (120), it may perform a predetermined processing operation, for example, a copying operation, to transmit the received signals to RU (130). When copying is performed, approximately 0.5 usec (150) may be required.

[0065] HU (125) can transmit the signal received from MU (120) back to RU (130) after CPRI conversion processing. At this time, the time required to transmit the signal from HU (125) to RU (130) through the CPRI interface may be approximately 2 usec.

[0066] When the RU (130) receives a signal from the HU (125), it can perform various digital signal processing to transmit the signal to a terminal (not shown) located within the coverage of the RU (130) and convert the processed signal into an analog signal (130a). At this time, the time required for signal processing in the RU (130) can be referred to as a processing delay of the RU (130), for example, a DSP delay (155). Then, the RU (130) can radiate the analogized signal to the terminal through an antenna (not shown) after processing such as amplification. Meanwhile, for the convenience of explanation, the processing delay of the RU (130) is exemplified as a DSP delay, but is not limited thereto, and the processing delay of the RU (130) may be a concept that further includes a delay from analogization to radiating through an antenna.

[0067] Typically, distributed antenna systems (DASs) utilize an algorithm that compensates for delay on each path based on the maximum path delay value, similar to the delay compensation method used in legacy base stations. However, the delay compensation method compliant with the O-RAN standard differs from the method used in legacy base stations and DASs. This will be described in detail later in Figure 2.

[0068]

[0069] FIG. 2 is a diagram illustrating a delay processing method of an O-RAN base station. FIG. 2 may be a delay processing method performed at an O-RAN base station (105 of FIG. 1) according to one embodiment of the present disclosure. For convenience of explanation, the following description will be made with reference to FIG. 1.

[0070] Referring to FIGS. 1 and 2, the O-RAN base station (105) can perform delay processing on a signal transmitted to the MU (120) according to the O-RAN standard.

[0071] The receive window (Rx window) (210) in the delay profile range defined in the O-RAN standard may have a range of 223 usec from -357 to -134 usec (microseconds) from the reference transmission time point (205) in a TDD environment, for example, 1 PPS (pulse per second) (or 10 msec sync). Accordingly, the O-RAN base station (105) may transmit a data packet with a timing advance at about -132 usec based on the reference transmission time point (205). At this time, the O-RAN base station (105) may further consider the processing delay value according to the eCPRI and LowPHY processing occurring in the MU (120). That is, the O-RAN base station (105) may additionally adjust the transmission time point by the processing delay value according to the eCPRI and LowPHY processing so that data can be transmitted to the terminal in synchronization with the reference transmission time point (205).

[0072] Looking more closely at the time interval (220) between the receiving window (210) and the reference transmission time point (205), the time (230) from the reference transmission time point (205) to the receiving window (210) is approximately 134 usec, and the time (240) for transmitting a packet at 1PPS from the O-RAN base station (105) may be approximately 132 usec. By subtracting approximately 27 usec, which is the processing delay time (250) of the eCPRI and LowPHY within the MU (120), from the time (240) for transmitting the packet, the data transmission time point (225) of the O-RAN base station (105) may be determined. The data transmission time (225) is a time point that is ahead of the reference transmission time (205) by a time advance value (advanced data time) (260), and the O-RAN base station (105) transmits a packet at the timing advanced data transmission time (225) so that data can be transmitted to the terminal at the reference transmission time (205). The O-RAN base station (105) can transmit the packet by timing advancing it so that the calculated data transmission time (225) includes Hyper Frame Number (HFN) 0 (270) and Base Frame Number (BFN) 0 (280).

[0073] As described above, the O-RAN base station (105) transmits the transmission target signal (data packet) to the MU (120) of the distributed antenna system with a timing advance, regardless of whether the legacy base station (110) is connected to the distributed antenna system. Accordingly, when the distributed antenna system also supports the legacy base station (110), synchronization between the signal from the O-RAN base station (105) and the signal from the legacy base station (110) may be a problem.

[0074] Below, an algorithm for performing delay compensation, i.e. signal synchronization, for base station signals of the distributed antenna system is described.

[0075]

[0076] FIG. 3 is a diagram illustrating a method for performing downlink delay compensation in a communication system according to one embodiment of the present disclosure.

[0077] FIG. 3 may illustrate a method for compensating for the delay time of received signals in order to synchronize signals received from an O-RAN base station and signals received from a legacy base station by a distributed antenna system, more specifically, an MU, in a communication system. In describing FIG. 3, it is assumed that an O-RAN base station and a legacy base station are connected to the distributed antenna system as in FIG. 1, and that the distributed antenna system is composed of an RIU, an MU, an HU, and an RU.

[0078] Referring to FIG. 3, the MU (350) can obtain a timing parameter value, for example, a time advance value (310), described in FIG. 2 from a reference transmission time point (305). The time advance value (310) may be approximately 105 usec. The reference transmission time point (305) may indicate a timing at which a signal is transmitted from the RU (370) to the terminal as a synchronization criterion in a TDD environment, and may be 1PPS, etc., as described in FIG. 2. According to an embodiment, the MU (350) may obtain the time advance value (310) from a connected O-RAN base station, a management entity of the distributed antenna system, etc. However, the present invention is not limited thereto, and the MU (350) may also obtain the time advance value (310) based on a received signal.

[0079] The MU (350) can determine the first data transmission time point (315a) that is earlier than the reference transmission time point (305) by a time advance value (310). However, since the MU (350) must perform compensation delay by considering signals received from not only the O-RAN base station but also the connected legacy base station, the delay between the MU (350) and the HU (360) (hereinafter, MU-HU transmission delay) (320) and the delay between the HU (360) and the RU (370) (hereinafter, HU-RU delay) (330) can be considered together. The MU-HU delay (320) and the HU-RU delay (330) may be concepts that include transmission delay that occurs when a signal is transmitted between units through a link, processing delay that occurs in the process of processing data, etc. In other words, the delay between the units described above may indicate the time at which data received from a specific unit is received by another unit when the data is processed and transmitted to another unit. In some embodiments, the MU (350) may receive information about inter-unit delay from the management entity of the distributed antenna system, such as the HU (360) or the RU (370). Alternatively, the MU (350) may measure delay for lower communication nodes, such as the HU (360) or the RU (370), in a predetermined manner. For example, the delay between units may be measured using various methods, such as a method of measuring one-way delay based on timestamps between the CPRI REC of the MU (350) and the CPRI RE of the HU (360).

[0080] The MU (350) can determine a second data transmission time point (315b) that is delayed by the MU-HU delay (320) from the first data transmission time point (315a). The second data transmission time point (315b) can be identified as the time at which data is received by the HU (360) when the MU (350) transmits data at the first data transmission time point (315a).

[0081] The MU (350) can determine a third data transmission time point (315c) that is delayed by the HU-RU delay (330) from the second data transmission time point (315b). The third data transmission time point (315c) can be identified as the time at which data is received by the RU (370) when the HU (360) transmits data at the second data transmission time point (315b).

[0082] MU (350) can additionally adjust the delay amount by the processing delay of RU (e.g., DSP delay (155) of FIG. 1) at the third data transmission time point (315c).

[0083] In this way, the MU (350) can determine the delay control value (340) based on the time advance value (310), the combined delay value that adds up the transmission delay between the node units constituting the distributed antenna system and the processing delay of the lowest node unit. The delay control value (340) can be a value obtained by subtracting the combined delay value from the time advance value (310).

[0084] And, MU (350) can perform delay compensation on signals received from O-RAN base station based on delay control value (340), and can perform delay compensation on signals received from legacy base station based on the combined delay value. Accordingly, signals received from O-RAN base station and legacy base station can be synchronized to the reference transmission time point (305) and transmitted to terminals from RU (370) without interference.

[0085] Meanwhile, the above-described delay compensation method can be applied only when the time advance value (310) is greater than the sum of the MU-HU delay (320) and the HU-RU delay (330).

[0086] Meanwhile, in an embodiment, when the delay paths from the MU (350) to each RU have different topologies, such as when the distributed antenna system is connected to the RU (370) and other RU(s) in the HU (360), the MU (350) can determine the above-described delay control value based on the maximum combined delay value among the combined delay values ​​of each of the delay paths, and can perform delay compensation on base station signals using the determined delay control value.

[0087]

[0088] FIG. 4 is a diagram for explaining a method for performing delay compensation of an uplink in a communication system according to one embodiment of the present disclosure.

[0089] FIG. 4 illustrates a method for node units to compensate for delay times based on uplink in a distributed antenna system that integrates O-RAN base stations and legacy base stations. In describing FIG. 4, it is assumed that the distributed antenna system, as in FIG. 1, is comprised of RIUs, MUs, HUs, and RUs.

[0090] Referring to FIG. 4, the RU (410) of the distributed antenna system can receive an uplink signal at a specific point in time after delay compensation for downlink signals as in FIG. 3. For example, the RU (410) can receive the uplink signal at a 1PPS position. The RU (410) can input the uplink signal to the CPRI REC side together with a 10msec synchronization signal to transmit the received uplink signal to the HU (420).

[0091] The CPRI mapper of the RU (410) can transmit information about the input synchronization signal, uplink signal (data), timing of data loading, etc. to the HU (420). The information may include, for example, a basic frame index (440), a hyper frame index (450), a base frame number (460), etc. For example, the information about the timing of data loading may include information about the amount of delay to be compensated for.

[0092] HU (420) can obtain uplink data and information received from RU (410) via CPRI RE. HU (420) can perform a predetermined process on the uplink data considering the delay between RU (410) and HU (420), update the information, and transmit the uplink data and information to MU (430).

[0093] MU (430) can also obtain uplink data and information received from HU (420) via CPRI RE. MU (430) can perform certain processing on uplink data considering the delay between HU (420) and MU (430), update the information, and transmit the uplink data and information to an O-RAN base station or legacy base station.

[0094]

[0095] FIG. 5 is a block diagram schematically illustrating the structure of a communication system according to one embodiment of the present disclosure. MU (510), HU (520), and RU (530) illustrated in FIG. 5 may be identical to or similar to MU (120, 350, 430), HU (125, 360, 420), and RU (130, 370, 410) described in FIGS. 1 to 4, and the main components for signal processing of each unit based on the downlink are exemplarily illustrated.

[0096] Referring to FIG. 5, MU (510) may have a structure that supports both O-RAN base stations and RF base stations, and may include first to third blocks (540, 545, 550).

[0097] The first block (540) may include an eCPRI and LowPHY function that receives an O-RAN base station signal and an eCPRI synchronization control signal that conform to the eCPRI standard transmitted from an O-RAN base station. The processing described in FIG. 2 may be performed on the signal received by the eCPRI and LowPHY function.

[0098] The second block (545) can perform delay processing on legacy base station signals that follow the eCPRI standard transmitted through the legacy base station and the RIU. The second block (545) can perform delay processing on the legacy base station signals based on the delay between the RIU and the MU.

[0099] The third block (550) can perform delay compensation for synchronization of signals received from an O-RAN base station and a legacy base station. The third block (550) can adjust the delay of the O-RAN base station signal with a delay control value calculated based on a timing parameter value (time advance value) of the O-RAN base station signal and a summation delay value (including a transmission delay between an MU and an HU, a transmission delay between an HU and an RU, etc.). In addition, the third block (550) can adjust the delay of the legacy base station signal based on the summation delay value. The third block (550) can be configured as a multiplexer, and synchronization of the O-RAN base station signal and the legacy base station signal can be enabled through the above-described delay adjustment (compensation) processing.

[0100] HU (520) may include a fourth block (560). The fourth block (560) may correct delay values ​​of the CPRI link, etc. for received signals.

[0101] RU (530) may include a fifth block (570). The fifth block (570) may also correct delay values ​​of the CPRI link for received signals.

[0102] Meanwhile, although not shown, it is of course possible for blocks of each unit to be configured to perform delay compensation processing on the uplink path.

[0103]

[0104] FIG. 6 is a schematic diagram illustrating the configuration of a main unit according to one embodiment of the present disclosure.

[0105] The main unit (600) of FIG. 6 may be the same as or similar to the MU (120, 350, 430, 510) of FIGS. 1 to 5.

[0106] A main unit (600) according to one embodiment of the present disclosure may include a processor (610) that controls the overall operation of the main unit (600), a transceiver (or transceiver unit) (620) including a transmitter and a receiver, and a memory (630). Of course, the present invention is not limited to the above example, and the main unit (600) may include more or fewer components than the configuration illustrated in FIG. 6.

[0107] According to one embodiment of the present disclosure, the transceiver (620) can transmit and receive signals with other network nodes (e.g., ODU, RIU, HU). The signals transmitted and received by the main unit can include C-plane, U-plane, S-plane, M-plane signals, uplink data, and downlink data. In addition, the transceiver (620) can receive signals through a path such as Fiber, transmit them to the processor (610), and transmit signals determined and output by the processor (610). The transceiver (620) is not configured as a single structure, and can include a function for performing communication with an O-RAN base station (e.g., a synchronization processing function including an eCPRI layer and a LowPHY layer). In addition, it can include a function for performing communication with an RF base station (e.g., a synchronization processing function).

[0108] According to one embodiment of the present disclosure, the processor (610) can control the main unit to perform any one of the operations of the embodiments of FIGS. 1 to 5. Meanwhile, the processor (610), the memory (630), and the transceiver (620) do not necessarily have to be implemented as separate modules, and can of course be implemented as a single component in the form of a single chip. In addition, the processor (610), the memory (630), and the transceiver (620) can be electrically connected. In addition, the processor (610) can be an Application Processor (AP), a Communication Processor (CP), a circuit, an application-specific circuit, or at least one processor. The processor (610) of the main unit (600) can include a delay control function for performing a delay compensation or synchronization operation. The delay control function can perform synchronization of signals by applying the delay compensation method proposed in FIGS. 1 to 5 to signals received from the transceiver. Each function may be included as a separate device and may be included in the processor (610) as a function.

[0109] According to one embodiment of the present disclosure, the memory (630) can store data such as basic programs, application programs, and setting information for the operation of the main unit. In addition, the memory (630) can store uplink data and downlink data (user plane, control plane) received by the main unit. In particular, the memory (630) can provide the stored data according to a call of the processor (610). The memory (630) can be configured as a storage medium or a combination of storage media such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD. In addition, there can be a plurality of memories (630). In addition, the processor (610) can perform the above-described embodiments of the present disclosure based on a program for performing the above-described embodiments stored in the memory (630).

[0110]

[0111] FIG. 7 is a schematic diagram illustrating the configuration of a hub unit according to one embodiment of the present disclosure.

[0112] The hub unit (700) of FIG. 7 may be identical to or similar to the HU (125, 360, 420, 520) of FIGS. 1 to 5.

[0113] A hub unit (700) according to one embodiment of the present disclosure may include a processor (710) that controls the overall operation of the hub unit (700), a transceiver (or transceiver unit) (720) including a transmitter and a receiver, and a memory (730). Of course, the present invention is not limited to the above example, and the hub unit (700) may include more or fewer components than the configuration illustrated in FIG. 7.

[0114] According to one embodiment of the present disclosure, the transceiver (720) can transmit and receive signals with other network nodes (e.g., MUs, RUs). The signals transmitted and received by the hub unit can include C-plane, U-plane, S-plane, M-plane signals, uplink data, and downlink data. In addition, the transceiver (720) can receive signals through a path such as a fiber, transmit the signals to the processor (710), and transmit the signals determined and output by the processor (710).

[0115] According to one embodiment of the present disclosure, the processor (710) can control the hub unit to perform any one of the operations of the embodiments of FIGS. 1 to 5. Meanwhile, the processor (710), the memory (730), and the transceiver (720) do not necessarily have to be implemented as separate modules, and can of course be implemented as a single component in the form of a single chip. In addition, the processor (710), the memory (730), and the transceiver (720) can be electrically connected. In addition, the processor (710) can be an Application Processor (AP), a Communication Processor (CP), a circuit, an application-specific circuit, or at least one processor. The processor (710) of the hub unit (700) can include a delay control function for performing a delay compensation or synchronization operation. The delay control function can perform synchronization of signals by applying the delay compensation method proposed in FIGS. 1 to 5 to signals received from the transceiver. Each function may be included as a separate device and may be included in the processor (710) as a function.

[0116] According to one embodiment of the present disclosure, the memory (730) can store data such as a basic program, an application program, and setting information for the operation of the hub unit. In addition, the memory (730) can store uplink data and downlink data (user plane, control plane) received by the hub unit. In particular, the memory (730) can provide the stored data according to a call of the processor (710). The memory (730) can be configured as a storage medium or a combination of storage media such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD. In addition, there can be a plurality of memories (730). In addition, the processor (710) can perform the above-described embodiments based on a program for performing the above-described embodiments of the present disclosure stored in the memory (730).

[0117]

[0118] FIG. 8 is a schematic diagram illustrating the configuration of a remote unit according to one embodiment of the present disclosure.

[0119] The remote unit (800) of FIG. 8 may be identical to or similar to the RUs (130, 370, 410, 530) of FIGS. 1 to 5. The remote unit (800) may also be referred to as a wireless unit.

[0120] A remote unit (800) according to one embodiment of the present disclosure may include a processor (810) that controls the overall operation of the remote unit (800), a transceiver (or transceiver unit) (820) including a transmitter and a receiver, and a memory (830). Of course, the present invention is not limited to the above example, and the remote unit (800) may include more or fewer components than the configuration illustrated in FIG. 8.

[0121] According to one embodiment of the present disclosure, the transceiver (820) can transmit and receive signals with other network nodes (e.g., HUs) and terminals. The signals transmitted and received by the wireless unit can include C-plane, U-plane, S-plane, M-plane signals, uplink data, and downlink data. In addition, the transceiver (820) can receive signals through a path such as a fiber, transmit them to the processor (810), and transmit signals determined and output by the processor (810).

[0122] According to one embodiment of the present disclosure, the processor (810) may control the wireless unit to perform any one of the operations of the embodiments of FIGS. 1 to 5. Meanwhile, the processor (810), the memory (830), and the transceiver (820) do not necessarily have to be implemented as separate modules, and may of course be implemented as a single component in the form of a single chip. In addition, the processor (810), the memory (830), and the transceiver (820) may be electrically connected. In addition, the processor (810) may be an Application Processor (AP), a Communication Processor (CP), a circuit, an application-specific circuit, or at least one processor. The processor (810) of the remote unit (800) may include a delay control function for performing a delay compensation or synchronization operation. The delay control function may perform synchronization of signals by applying the delay compensation method proposed in FIGS. 1 to 5 to signals received from the transceiver. Each function may be included as a separate device and may be included in the processor (810) as a function.

[0123] According to one embodiment of the present disclosure, the memory (830) can store data such as basic programs, application programs, and setting information for the operation of the wireless unit. In addition, the memory (830) can store uplink data and downlink data (user plane, control plane) received by the hub unit. In particular, the memory (830) can provide the stored data according to a call of the processor (810). The memory (830) can be configured as a storage medium or a combination of storage media such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD. In addition, there can be a plurality of memories (830). In addition, the processor (810) can perform the above-described embodiments based on a program for performing the above-described embodiments of the present disclosure stored in the memory (830).

[0124]

[0125] The methods described with reference to FIGS. 1 through 5 in this disclosure comprise one or more steps or actions for achieving the described method. The method steps and / or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order for the steps or actions is specified, the order and / or use of specific steps and / or actions may be modified without departing from the scope of the claims.

[0126] Additionally, the various operations of the methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include, but are not limited to, various hardware and / or software component(s) and / or module(s), including application-specific integrated circuits (ASICs) or processors. In general, where there are corresponding operations in the drawings, these operations may have corresponding counterpart means + functional components with the same number.

[0127] The various illustrative logic blocks, modules, and circuits described in connection with the present disclosure may be implemented or performed by a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0128] The term "determining" as described above encompasses a wide variety of actions. For example, "determining" can include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, database, or other data structure), verifying, and the like. Furthermore, "determining" can include receiving (e.g., receiving information), accessing (e.g., accessing data in memory), and the like. Furthermore, "determining" can include resolving, selecting, choosing, establishing, and the like.

[0129]

[0130] Anyone with ordinary skill in the art to which the present disclosure pertains will be able to make various modifications and variations without departing from the essential characteristics of the technical idea of ​​the present disclosure.

[0131] Accordingly, the embodiments illustrated in the present disclosure are not intended to limit the technical idea of ​​the present disclosure but rather to explain it, and the scope of the technical idea of ​​the present disclosure is not limited by these embodiments.

[0132] The scope of protection of the technical idea of ​​the present disclosure should be interpreted by the claims below, and all technical ideas within the equivalent scope should be interpreted as being included in the technical virtual scope of the present disclosure.

Claims

1. A method performed by a communication node communicatively connected to at least one lower communication node in a communication system, A step of receiving a first signal from an O-RAN (Open-Radio Access Network) base station; A step of receiving a second signal from a legacy base station; A step of determining a delay control value based on a predetermined timing parameter value for the first signal and a sum delay of the communication system; and A step of delay compensating the first signal based on the delay control value so that the first signal is synchronized with the second signal at the reference transmission time; A method comprising:

2. In paragraph 1, The step of determining the above delay control value is: A step of determining the delay control value by calculating the difference between the timing parameter value and the sum delay value; A method comprising:

3. In paragraph 1, A step of delay compensating the second signal based on the above sum delay value; A method further comprising:

4. In paragraph 1, A method wherein the timing parameter value is a value determined in advance based on a reception window range of the O-RAN base station, the reference transmission time, and a processing delay for the first signal at the communication node.

5. In paragraph 1, A method wherein the above-mentioned combined delay value includes a transmission delay value between the communication node and the lower communication node, and a processing delay value in the lower communication node.

6. In paragraph 1, The above communication system is a distributed antenna system, The above communication node is the main unit of the distributed antenna system, A method wherein the above-mentioned lower communication node is a remote unit of the distributed antenna system.

7. In paragraph 1, A method wherein the first and second signals are signals that comply with the eCPRI (enhanced Common Public Radio Interface) standard.

8. In paragraph 1, A method in which the above communication node and the above sub-communication node are connected through a CPRI-based interface.

9. A communication node that is communicatively connected to at least one lower communication node in a communication system, memory; A transceiver for receiving a first signal from an Open-Radio Access Network (O-RAN) base station and a second signal from a legacy base station, and transmitting the first and second signals to the lower node; and At least one processor operatively connected to the memory and the transceiver; Includes, The above memory, when executed, causes the at least one processor to: Determine a delay control value based on a predetermined timing parameter value for the first signal and a sum delay value of the communication system, A communication node storing instructions for compensating for delay of the first signal based on the delay control value so that the first signal is synchronized with the second signal at a reference transmission time.

10. In paragraph 9, When the above instructions are executed, the at least one processor: A communication node that determines the delay control value by calculating the difference between the timing parameter value and the sum delay value.

11. In paragraph 9, When the above instructions are executed, the at least one processor: A communication node that compensates for the delay of the second signal based on the above-mentioned combined delay value.

12. In paragraph 9, A communication node, wherein the timing parameter value is a value determined in advance based on the reception window range of the O-RAN base station, the reference transmission time, and the processing delay for the first signal at the communication node.

13. In paragraph 9, A communication node in which the above-mentioned combined delay value includes a transmission delay value between the communication node and the lower communication node, and a processing delay value in the lower communication node.

14. In paragraph 9, The above communication system is a distributed antenna system, The above communication node is the main unit of the distributed antenna system, The above-mentioned lower communication node is a communication node that is a remote unit of the distributed antenna system.

15. In paragraph 9, The above first and second signals are signals that follow the eCPRI (enhanced Common Public Radio Interface) standard, a communication node.

16. In paragraph 9, The above communication node is a communication node connected to the lower communication node through a CPRI-based interface.

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