Apparatus and method for performing barring

Abstract

This distributed unit (DU) may comprise at least one processor. The at least one processor may be configured to: obtain, from a central unit (CU) connected to the DU through an F1 interface, CU load information indicating the load of the CU; determine a unified access control (UAC) barring factor and a UAC barring time on the basis of the load of the CU indicated by the CU load information; and transmit, to a user equipment (UE), a system information block (SIB) including the UAC barring factor and the UAC barring time.

Description

Device and method for performing barring

[0001] The following descriptions relate to an apparatus and method for performing scheduling based on fronthaul capacity.

[0002] A base station may be implemented into a central unit (CU), a distributed unit (DU), and a radio unit (RU) according to function split. The CU may be configured to perform functions of the upper layer of the protocol stack (e.g., radio resource control (RRC), packet data convergence protocol (PDCP), and service data adaptation protocol (SDAP). The DU may be configured to perform some of the functions of the lower layer of the protocol stack (e.g., radio link control (RLC), medium access control (MAC), and high PHY (physical)). The RU may be configured to perform the remaining functions of the lower layer of the protocol stack (e.g., low PHY).

[0003] The information described above may be provided as related art for the purpose of aiding understanding of the present disclosure. No claim or determination is made as to whether any of the foregoing may be applied as prior art related to the present disclosure.

[0004] A distributed unit (DU) is provided. The DU may include a communication circuit. The DU may include a memory that stores instructions and includes one or more storage media. The DU may include at least one processor that includes a processing circuit. When the instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to obtain CU load information from the CU that indicates the load of the CU connected to the DU via an F1 interface. When the instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine a unified access control (UAC) barring factor and a UAC barring time based on the load of the CU indicated by the CU load information. When the above instructions are executed individually or collectively by the at least one processor, the DU may cause the system information block (SIB) including the UAC barring factor and the UAC barring time to be transmitted to the user equipment (UE).

[0005] A method performed by a DU is provided. The method may include the operation of obtaining CU load information from the CU that indicates the load of the CU (central unit) connected to the DU through an F1 interface. The method may include the operation of determining a UAC (unified access control) barring factor and a UAC barring time based on the load of the CU indicated by the CU load information. The method may include the operation of transmitting a SIB (system information block) including the UAC barring factor and the UAC barring time to a UE (user equipment).

[0006] In relation to the description of the drawings, the same or similar reference numerals may be used for identical or similar components.

[0007] Figure 1 illustrates an example of a wireless communication system.

[0008] Figure 2 illustrates an example of DSS.

[0009] FIG. 3a illustrates an example of signaling between a base station and a UE for transmitting information for UAC barring in NR.

[0010] FIG. 3b illustrates an example of signaling between a base station and a UE for transmitting information for access class barring in LTE.

[0011] Figure 4a illustrates examples of distributed arrangements.

[0012] FIG. 4b illustrates the components of a communication device.

[0013] FIGS. 5a to 5c illustrate examples of signaling for overload control.

[0014] Figure 6a illustrates a chart showing the load according to overload control.

[0015] Figure 6b illustrates a chart showing the load according to overload control.

[0016] FIG. 7 illustrates an example of signaling for exchanging information for overload control.

[0017] Figure 8 illustrates a flowchart showing the operations of the DU for overload control.

[0018] Figure 9 illustrates examples of UAC states of a DU for overload control.

[0019] Figure 10 is a flowchart showing the operations of the DU under normal load conditions.

[0020] FIG. 11 is a flowchart showing the operations of the DU under the first overload condition.

[0021] FIG. 12 is a flowchart showing the operations of the DU under a second overload condition.

[0022] Figure 13 illustrates an example of a combined UAC barring.

[0023] FIG. 14a illustrates a chart showing the load according to overload control.

[0024] FIG. 14b illustrates a chart showing the load according to overload control.

[0025] Figure 15 illustrates examples of signaling for barring in NR and LTE.

[0026] The terms used in this disclosure are used merely to describe specific embodiments and are not intended to limit the scope of other embodiments. A singular expression may include a plural expression unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as generally understood by those skilled in the art described in this disclosure. Terms used in this disclosure that are defined in a general dictionary may be interpreted as having the same or similar meaning as they have in the context of the relevant technology, and are not to be interpreted in an ideal or overly formal sense unless explicitly defined in this disclosure. In some cases, even terms defined in this disclosure are not to be interpreted to exclude the embodiments of this disclosure.

[0027] In the various embodiments of the present disclosure described below, a hardware-based approach is described as an example. However, since the various embodiments of the present disclosure include techniques using both hardware and software, the various embodiments of the present disclosure do not exclude a software-based approach.

[0028] Terms referring to signals used in the following description (e.g., packet, message, signal, information, signaling), terms referring to resources (e.g., section, symbol, slot, subframe, radio frame, subcarrier, RE (resource element), RB (resource block), BWP (bandwidth part), occasion)), terms for operation states (e.g., step, operation, procedure)), terms referring to data (e.g., packet, message, user stream, information, bit, symbol, codeword)), terms referring to channels, terms referring to network entities (DU (distributed unit), RU (radio unit), CU (central unit), CU-CP (control plane), CU-UP (user plane), O-DU (O-RAN (open radio access network) DU), O-RU (O-RAN RU), O-CU (O-RAN CU), Terms such as O-CU-UP (O-RAN CU-CP), O-CU-CP (O-RAN CU-CP), and terms referring to components of the device are examples provided for convenience of explanation. Accordingly, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may be used. Furthermore, terms such as '...part', '...device', '...object', '...body' used below may refer to at least one shape structure or a unit that processes a function.

[0029] Additionally, in this disclosure, expressions of "greater than" or "less than" may be used to determine whether a specific condition is satisfied or fulfilled; however, this is merely for the purpose of expressing an example and does not exclude descriptions of "greater than" or "less than." Conditions described as "greater than" may be replaced with "greater than," conditions described as "less than" may be replaced with "less than," and conditions described as "greater than and less than" may be replaced with "greater than and less than." Furthermore, "A" to "B" below refer to at least one of elements from A (including A) to B (including B). Below, "C" and / or "D" refers to including at least one of "C" or "D," i.e., {"C", "D", "C" and "D"}.

[0030] The present disclosure describes embodiments using terms used in some communication standards (e.g., 3GPP (3rd Generation Partnership Project) and / or O-RAN (open-radio access network)), but this is merely illustrative. The embodiments of the present disclosure may also be applied to other communication systems.

[0031] Figure 1 illustrates an example of a wireless communication system.

[0032] Referring to FIG. 1, a wireless communication system may include a base station (110) and a UE (user equipment) (120) as part of nodes utilizing a wireless channel. FIG. 1 illustrates a base station (110) and a UE (120), but the present disclosure is not limited thereto. For example, the wireless communication system may further include other base stations and / or other UEs.

[0033] In one embodiment, a base station (110) is an infrastructure for providing wireless access to a UE (120). The base station (110) may have coverage defined based on the distance over which it can transmit signals. In addition to base station, the base station (110) may be referred to as an 'access point (AP)', 'eNodeB (eNB)', '5G node (5th generation node)', 'next generation nodeB (gNB)', 'wireless point', 'transmission / reception point (TRP)', 'RAN (radio access network) node', 'NG (new generation)-RAN node', or other terms having an equivalent technical / functional meaning.

[0034] In one embodiment, the UE (120) is a device used by a user and can communicate with a base station (110) via a wireless channel. The link from the base station (110) to the UE (120) may be referred to as a downlink (DL), and the link from the UE (120) to the base station (110) may be referred to as an uplink (UL). The UE (120) may be referred to as a 'terminal', 'customer premises equipment' (CPE), 'mobile station', 'subscriber station', 'remote terminal', 'wireless terminal', 'electronic device', or 'user device', or other terms having an equivalent technical or functional meaning, in addition to UE (user equipment).

[0035] The base station (110) illustrated in FIG. 1 may be implemented based on a distributed deployment using a central unit (CU), a distributed unit (DU), and / or a radio unit (RU). The distributed deployment of the base station (110) is described in FIG. 4a.

[0036] Figure 2 illustrates an example of DSS.

[0037] Referring to FIG. 2, the communication system may include an LTE (long term evolution) scheduler (210) and an NR (new radio) scheduler (220). For example, the LTE scheduler (210) and the NR scheduler (220) may be implemented in separate devices. However, the present disclosure is not limited thereto. For example, the LTE scheduler (210) and the NR scheduler (220) may be implemented in a single device.

[0038] For example, the LTE scheduler (210) and the NR scheduler (220) can perform dynamic spectrum sharing (DSS) based on cooperation. DSS is a technology that enables LTE and NR to use the same frequency band concurrently. For example, by performing DSS, the LTE scheduler (210) and the NR scheduler (220) can dynamically allocate LTE resources and NR resources in the same frequency band on an hourly basis.

[0039] Referring to FIG. 2, according to the DSS, LTE and NR may share the same frequency band. For example, at a transmission time interval (TTI) (231), the LTE scheduler (210) and the NR scheduler (220) may allocate LTE resources for the corresponding frequency band. For example, at a TTI (232), the LTE scheduler (210) and the NR scheduler (220) may allocate LTE resources for part of the corresponding frequency band and NR resources for the remainder. For example, at a TTI (233), the LTE scheduler (210) and the NR scheduler (220) may allocate LTE resources for part of the corresponding frequency band and NR resources for the remainder. For example, at a TTI (234), the LTE scheduler (210) and the NR scheduler (220) may allocate NR resources for the corresponding frequency band. For example, in TTI (235), the LTE scheduler (210) and the NR scheduler (220) may allocate LTE resources for a portion of the frequency band and NR resources for the remainder. For example, in TTI (236), the LTE scheduler (210) and the NR scheduler (220) may allocate NR resources for the frequency band. For example, in TTI (237), the LTE scheduler (210) and the NR scheduler (220) may allocate LTE resources for a portion of the frequency band and NR resources for the remainder. For example, in TTI (238), the LTE scheduler (210) and the NR scheduler (220) may allocate LTE resources for a portion of the frequency band and NR resources for the remainder. For example, in TTI (239), the LTE scheduler (210) and the NR scheduler (220) may allocate LTE resources for the corresponding frequency band. However, the resource allocation shown in FIG. 2 is merely an example and the present disclosure is not limited thereto.For example, resource allocation may differ from the example shown in Fig. 2.

[0040] FIG. 3a illustrates an example of signaling between a base station and a UE for transmitting information for UAC barring in NR. The communication system of FIG. 3a may include a base station (110) and a UE (user equipment) (120). The base station (110) of FIG. 3a may be a base station that supports NR (new radio). In one example, the NR-supporting base station may be implemented using a CU (central unit) (410), a DU (distributed unit) (420), and / or a RU (radio unit) (430). The base station (110) implemented using the CU (410), DU (420), and / or RU (430) is described in FIG. 4a. In one example, the NR-supporting base station (110) may be referred to as an NR base station or other terms having an equivalent technical / functional meaning.

[0041] In FIG. 3a, a method for transmitting information for unified access control (UAC) barring from a base station (110) to a UE (120) in NR is described.

[0042] Referring to FIG. 3a, in operation 301, a base station (110) according to one embodiment may transmit a system information block (SIB) 1 to a UE (120). For example, the base station (110) may transmit the SIB 1 to the UE (120) by broadcasting the SIB 1. For example, the SIB 1 may include information for evaluating whether the UE (120) can access a cell, scheduling information of other system information (OSI), radio resource control (RRC) information common to all UEs, and / or barring information applicable to UAC. In one example, the contents of the information included in the SIB 1 may be referenced from the 3GPP (3rd generation partnership project) technical specification (TS) 38.331.

[0043] In one embodiment, the barring information applied to the UAC may indicate the UAC barring factor and / or the UAC barring time.

[0044] In one embodiment, the UAC barring factor may indicate the probability that an access attempt will be allowed during an access barring check. In one example, the UAC barring factor may indicate one of 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.30, 0.40, 0.50, 0.60, 0.70, 0.75, 0.80, 0.85, 0.90, or 0.95. However, this is merely an example and the present disclosure is not limited thereto. For example, the UAC barring factor may indicate a value other than those described above, and / or may indicate only some of the values ​​described above. In one example, the UAC barring factor may be referred to as 'uac-BarringFactor'.

[0045] In one embodiment, the UAC barring time may be the average time from when an access attempt is barred until a new access attempt is performed in an access barring check for the same access category. In one example, the UAC barring time may be one of 4 seconds, 8 seconds, 16 seconds, 32 seconds, 64 seconds, 128 seconds, 256 seconds, or 512 seconds. However, this is merely an example and the present disclosure is not limited thereto. For example, the UAC barring time may be a time other than the times described above, and / or only a portion of the times described above. In one example, the UAC barring time may be referred to as 'uac-BarringTime'.

[0046] In one embodiment, the UE (120) may perform an access barring check. For example, the UE (120) may generate a uniformly distributed random number between 0 and 1. For example, the UE (120) may identify that an access attempt is permitted if the generated random number is less than or equal to a value indicated by the UAC barring factor. In another example, the UE (120) may identify that an access attempt is barred if the generated random number exceeds a value indicated by the UAC barring factor.

[0047] In one embodiment, the UE (120) may generate a random number with a uniform distribution between 0 and 1 when an access attempt is barred. For example, the UE (120) may determine a timer based on the generated random number and the time indicated by the UAC barring time. In one example, the timer may be determined according to Equation 1 below.

[0048]

[0049] In Equation 1, T390 is a timer. T390 is the duration during which the UE (120) treats a cell as barred for the corresponding access category. rand is a random number. uac-BarringTime is a value indicated by the UAC barring time. For example, the UE (120) may start a timer (e.g., T390) when an access attempt is barred. The UE (120) may consider that barring for the corresponding access category is alleviated when the timer (e.g., T390) expires.

[0050] FIG. 3b illustrates an example of signaling between a base station and a UE for transmitting information for access class barring in LTE. The communication system of FIG. 3b may include a base station (110) and a UE (user equipment) (120). The base station (110) of FIG. 3b may be a base station that supports LTE (long term evolution). In one example, the LTE-supporting base station may be referred to as an LTE base station, an eNB (eNodeB), or other terms having an equivalent technical / functional meaning.

[0051] In FIG. 3b, a method for transmitting information for access class barring in LTE from a base station (110) to a UE (120) is described.

[0052] Referring to FIG. 3b, in operation 311, a base station (110) according to one embodiment may transmit a system information block (SIB) 1 to a UE (120). For example, the base station (110) may transmit the SIB 1 to the UE (120) by broadcasting the SIB 1. For example, the SIB 1 may include information for evaluating whether the UE (120) can access a cell and / or scheduling information of other system information (OSI). In one example, the contents of the information included in the SIB 1 may be referenced from 3GPP (3rd generation partnership project) TS (technical specification) 36.331.

[0053] In one embodiment, the OSI scheduling information may include a list of SIBs mapped to SIB1, the periodicity of the SIBs, and / or a scheduling window length for the SIBs. For example, the list may include SIBs associated with the OSI scheduling information included in SIB1. In one example, the list may always include SIB2. For example, the period may represent the transmission period of the SIBs. In one example, the period may be one of 8RF (radio frame), 16RF, 32RF, 64RF, 128RF, 256RF, or 512RF. For example, the scheduling window length may represent the time length for monitoring (or receiving) the SIBs. In one example, the scheduling window length may be one of 1ms (millisecond), 2ms, 5ms, 15ms, 20ms, or 40ms.

[0054] In operation 312, a base station (110) according to one embodiment may transmit SIB2 to a UE (120). For example, the base station (110) may transmit SIB2 to the UE (120) by broadcasting SIB2. For example, the UE (120) may receive SIB2 based on scheduling information contained in SIB1.

[0055] In one embodiment, SIB2 may include radio resource control (RRC) information common to all UEs and / or information for access class barring.

[0056] In one embodiment, information for access class barring may indicate an access class (AC) barring factor and / or an AC barring time.

[0057] In one embodiment, the AC barring factor may indicate the probability that an access attempt will be allowed during an access barring check. In one example, the AC barring factor may indicate one of 0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.40, 0.50, 0.60, 0.70, 0.75, 0.80, 0.85, 0.90, or 0.95. However, this is merely an example and the present disclosure is not limited thereto. For example, the AC barring factor may indicate a value other than those described above, and / or only some of the values ​​described above. In one example, the AC barring factor may be referred to as 'ac-BarringFactor'.

[0058] In one embodiment, the AC barring time may be the average time from when an access attempt is barred until a new access attempt is performed. In one example, the AC barring time may be one of 4 seconds, 8 seconds, 16 seconds, 32 seconds, 64 seconds, 128 seconds, 256 seconds, or 512 seconds. However, this is merely an example and the present disclosure is not limited thereto. For example, the AC barring time may be a time other than the times described above, and / or only a portion of the times described above. In one example, the AC barring time may be referred to as 'ac-BarringTime'.

[0059] In one embodiment, the UE (120) can perform an access barring check. For example, the UE (120) can generate a uniformly distributed random number between 0 and 1. For example, the UE (120) can identify that an access attempt is permitted if the generated random number is less than or equal to a value indicated by an AC barring factor. In another example, the UE (120) can identify that an access attempt is barred if the generated random number exceeds a value indicated by an AC barring factor.

[0060] In one embodiment, the UE (120) may generate a random number with a uniform distribution between 0 and 1 when an access attempt is barred. For example, the UE (120) may determine a timer based on the generated random number and the time indicated by the AC barring time. In one example, the timer may be determined according to Equation 2 below.

[0061]

[0062] In Equation 2, Tbarring is a timer. Tbarring is the duration during which the UE (120) treats a cell as barred for the corresponding access class. rand is a random number. ac-BarringTime is a value indicated by the AC barring time. For example, the UE (120) may start a timer (e.g., Tbarring) when an access attempt is barred. The UE (120) may consider that barring for the corresponding access class is alleviated when the timer (e.g., Tbarring) expires.

[0063] Figure 4a illustrates examples of distributed arrangements.

[0064] Referring to FIG. 4a, the base station (110) can be implemented using a CU (central unit) (410), a DU (distributed unit) (420), and / or a RU (radio unit) (430).

[0065] In one embodiment, the CU (410) may be configured to perform functions of the upper layer of the protocol stack (e.g., the radio resource control (RRC) layer and / or the service data adaptation protocol (SDAP) layer). For example, the CU (410) may be connected to the 5th generation core (5GC) (440). The 5GC (440) may include network functions of the core network (e.g., the access and mobility management function (AMF)).

[0066] In one embodiment, the DU (420) may be configured to perform the functions of the lower layer of the protocol stack (e.g., the RLC (radio link control) layer, the MAC (medium access control) layer, and / or the PHY (physical) layer).

[0067] In one embodiment, the DU (420) may be configured to perform some of the functions of a lower layer of the protocol stack (e.g., the PHY layer). The DU (420) may perform some of the functions of the PHY layer (high PHY), and the RU (430) may be configured to perform the remaining functions of the PHY layer (low PHY). An example of a function split between the DU (420) and the RU (430) related to the PHY layer may be as follows.

[0068] In one embodiment, the functions of the PHY layer in the downlink (DL) may include channel encoding / scrambling, modulation, layer mapping, antenna port mapping, RE (resource element) mapping, digital beamforming (e.g., precoding), iFFT (inverse fast Fourier transform) transform / CP (cyclic prefix) insertion, and / or RF (radio frequency) transformation. The functions of the PHY layer in the uplink (UL) may include RF conversion, FFT conversion / CP removal, digital beamforming (e.g., pre-combining, RE de-mapping), channel estimation, layer de-mapping, demodulation, and / or decoding / descrambling. For example, the DU (420) may be configured to perform some of the functions described above, and the RU (430) may be configured to perform the remaining functions.

[0069] For example, in the downlink of the first functional separation, the DU (420) may be configured to perform channel encoding / scrambling, modulation, layer mapping, antenna port mapping, RE mapping, and digital beamforming, and the RU (430) may be configured to perform iFFT transform / CP insertion and RF transform. In the uplink of the first functional separation, the RU (430) may be configured to perform RF transform, FFT transform / CP removal, and digital beamforming, and the DU (420) may be configured to perform RE de-mapping, channel estimation, layer de-mapping, demodulation, and decoding / scrambling. In one example, the first functional separation may be referred to as option 7-2x category A.

[0070] For example, in the downlink of the second function separation, the DU (420) may be configured to perform channel encoding / scrambling, modulation, layer mapping, antenna port mapping, and RE mapping, and the RU (430) may be configured to perform digital beamforming, iFFT transform / CP insertion, and RF transformation. In the uplink of the second function separation, the RU (430) may be configured to perform RF transformation, FFT transform / CP removal, and digital beamforming, and the DU (420) may be configured to perform RE de-mapping, channel estimation, layer de-mapping, demodulation, and decoding / scrambling. In one example, the second function separation may be referred to as option 7-2x category B.

[0071] Referring to the example (401) of FIG. 4a, the CU (410), DU (420), and RU (430) can be arranged independently.

[0072] Referring to the example (402) of FIG. 4a, the DU (420) and RU (430) may be implemented in the first device, and the CU (410) may be implemented in the second device. In the first device, the DU (420) and RU (430) may be logically distinguishable.

[0073] Referring to the example (403) of FIG. 4a, the RU (430) may be implemented in the first device, and the CU (410) and DU (420) may be implemented in the second device. In the second device, the CU (410) and DU (420) may be logically distinguishable.

[0074] Referring to the example (404) of FIG. 4a, the CU (410), DU (420), and RU (430) can be implemented within a single device. Within the device, the CU (410), DU (420), and RU (430) can be logically distinguished.

[0075] FIG. 4b illustrates the components of a communication device.

[0076] The communication device exemplified in FIG. 4b may be a DU (distributed unit) (420). However, the description of the processor (450), memory (460), and communication circuit (470) in FIG. 4b may be substantially the same applied to a CU (central unit) (410) and a base station (110).

[0077] Referring to FIG. 4b, the communication device may include a processor (450), a memory (460), and a communication circuit (470). For example, the processor (450), the memory (460), and the communication circuit (470) may be electrically and / or operably coupled with each other by a communication bus. Operatably coupled hardware components may mean that a direct or indirect connection between the hardware components is established via a wire (or wirelessly) so that a second hardware component (e.g., memory (460) and / or communication circuit (470)) is controlled by a first hardware component (e.g., processor (450)). The hardware components illustrated in FIG. 4b are illustrated based on different blocks, but the present disclosure is not limited thereto. For example, at least a portion of the hardware components shown in FIG. 4b (e.g., processor (450), memory (460), and / or communication circuit (470)) may be included in a single integrated circuit such as a system on chip (SoC) or a system in package (SIP).

[0078] In one embodiment, the communication device may include a processor (450). The processor (450) may include a hardware component for processing data based on one or more instructions. The processor (450) may include various processing circuits and / or a plurality of processors. For example, the term “processor” as used herein, including in the claims, may include various processing circuits including at least one processor, and one or more of said at least one processor may be configured to perform the various functions described below in a distributed manner, individually and / or collectively. As used below, where “processor,” “at least one processor,” and “one or more processors” are described as being configured to perform various functions, these terms encompass, for example but not limited to, situations where one processor performs some of the cited functions and another processor(s) perform other parts of the cited functions, and also situations where one processor can perform all of the cited functions. Additionally, the at least one processor may include a combination of processors that perform various enumerated / disclosed functions, for example, in a distributed manner. The at least one processor may execute program instructions to achieve or perform various functions.

[0079] In one embodiment, the communication device may include a memory (460). The memory (460) may include a hardware component for storing data and / or instructions that are input to or output from the processor (450). For example, the memory (460) may include a volatile memory such as random-access memory (RAM) and / or a non-volatile memory such as read-only memory (ROM). The volatile memory may include, for example, at least one of dynamic RAM (DRAM), static RAM (SRAM), cache RAM, and pseudo SRAM (PSRAM). The non-volatile memory may include, for example, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), flash memory, a hard disk, a compact disk, and an embedded multimedia card (eMMC).

[0080] In one embodiment, one or more instructions (or commands) representing operations and / or operations performed by the processor (450) may be stored within the memory (460) of the communication device. A set of one or more instructions may be referred to as a program, firmware, operating system, process, routine, sub-routine, and / or application. Hereinafter, the statement that an application is installed within the communication device may mean that one or more instructions provided in the form of an application are stored within the memory (460), and that one or more applications are stored in an executable format by the processor (450).

[0081] In one embodiment, the communication device may include a communication circuit (470). The communication circuit (470) may perform functions for transmitting and receiving signals in a wired communication environment. The communication circuit (470) may include a wired interface for controlling a direct connection between devices through a transmission medium (e.g., copper wire, optical fiber). For example, the communication circuit (470) may transmit an electrical signal to another device through a copper wire or perform conversion between an electrical signal and an optical signal. For example, the communication device may communicate with a central unit (CU) (410) through the communication circuit (470). For example, the communication device may communicate with a radio unit (RU) (430) through the communication circuit (470). For example, the communication device may communicate with a base station (110) through the communication circuit (470). For example, a first part of a communication circuit (470) that performs a function to communicate with a CU (410), a second part of a communication circuit (470) that performs a function to communicate with a RU (430), and / or a third part of a communication circuit (470) that performs a function to communicate with a base station (110) may be distinguished. However, this is merely an example and the present disclosure is not limited thereto. For example, at least a portion of the first part, the second part, and / or the third part may overlap.

[0082] FIGS. 5a through 5c illustrate examples of signaling for overload control. FIGS. 5a through 5c describe the 3GPP (3rd generation partnership project) procedures for overload control.

[0083] Referring to FIGS. 5a through 5c, the communication system may include a new generation-radio access network (NG-RAN) node (510) and an access and mobility management function (AMF) (520). For example, the NG-RAN node (510) may correspond to the base station (110) of FIG. 1. For example, the NG-RAN node (510) may be implemented using a central unit (CU) (410) and a distributed unit (DU) (420).

[0084] In operation 501, an NG-RAN node (510) according to one embodiment may receive (or obtain) an overload start message from an AMF (520). For example, in response to receiving the overload start message, the NG-RAN node (510) may identify that the AMF (520) is in an overloaded state.

[0085] In one embodiment, the overload start message may include an overload action parameter (or an information element). For example, the overload action parameter may indicate one of refusing to establish a radio resource control (RRC) connection for a non-emergency mobile originated data transfer, refusing to establish a RRC connection for signaling, allowing only emergency sessions and mobile terminated services, or allowing only high-priority sessions and mobile terminated services. In one example, for the content regarding the overload start message, reference may be made to sections 8.7.7, 9.2.6.14, 9.3.1.104, 9.3.1.105, 9.3.1.106, and 9.3.1.107 of 3GPP TS (technical specification) 38.413.

[0086] In operation 502, a DU (420) according to one embodiment may receive (or obtain) a network access rate reduction message from a CU (410). For example, the network access rate reduction message may include unified access control (UAC) assistance information. For example, the UAC assistance information may include UAC action parameters (or IE). In one example, regarding the network access rate reduction message, reference may be made to sections 8.2.9, 9.2.1.19, 9.3.1.83, and 9.3.1.84 of 3GPP TS 38.473.

[0087] In one embodiment, the UAC action parameter may indicate one of refusing to establish an RRC connection for non-urgent mobile outgoing data transmission, refusing to establish an RRC connection for signaling, allowing only urgent sessions and mobile incoming services, or allowing only high-priority sessions and mobile incoming services. In one example, the UAC action parameter may correspond to an overload action parameter obtained from the AMF (520).

[0088] In one example, if the UAC action parameter is set to reject RRC connection establishment for non-urgent mobile outgoing data transmission, the DU (420) can reject traffic corresponding to a specific RRC cause (e.g., 'mo-data', 'mo-SMS', 'mo-VidoeCall', and / or 'mo-VoiceCall').

[0089] In one example, if the UAC action parameter is set to reject RRC connection establishment for signaling, the DU (420) can reject traffic corresponding to specific RRC causes (e.g., 'mo-data', 'mo-SMS', 'mo-signaling', 'mo-VideoCall', and / or 'mo-VoiceCall').

[0090] In one example, if the UAC action parameter is set to allow only emergency sessions and mobile incoming services, the DU (420) may allow only traffic corresponding to specific RRC causes (e.g., 'emergency' and / or 'mt-Access').

[0091] In one example, if the UAC action parameter is set to allow only high-priority sessions and mobile incoming services, the DU (420) may allow only traffic corresponding to specific RRC causes (e.g., 'highPrioirityAccess', 'mps-PriorityAccess', 'mcs-PriorityAccess' and / or 'mt-Access').

[0092] In operation 503, an NG-RAN node (510) according to one embodiment may receive (or obtain) an overload stop message from an AMF (520). For example, in response to receiving the overload stop message, the NG-RAN node (510) may identify that the overload state of the AMF (520) has ended and normal operation has resumed. In one example, for the content of the overload stop message, reference may be made to Section 9.2.6.15 of 3GPP TS 38.413.

[0093] According to the 3GPP standard described in FIGS. 5a through 5c, the DU (420) can reduce the network access rate based on messages provided by the AMF (520) and / or CU (410) that have entered an overloaded state. However, the 3GPP standard does not define a method for reducing the network access rate from the AMF (520) and / or CU (410) that are not in an overloaded state. Additionally, since the network access rate reduction message is a unidirectional message, the DU (420) cannot provide feedback to the CU (410) regarding the response to the network access rate reduction and / or related key performance indicator (KPI) information. Furthermore, since the network access rate reduction message is a unidirectional message, the CU (410) must send multiple network access rate reduction messages to the DU (420) to ensure that the setting for the access rate reduction is reflected. Additionally, the DU (420) must perform the operation of managing and checking whether there is a change in information related to the reduction in network connection rate whenever it receives multiple network connection rate reduction messages.

[0094] FIG. 6a illustrates a chart showing the load according to overload control. FIG. 6a explains an example of an implementation of overload control based on the CPU (central processing unit) load of the CU (central unit) (410).

[0095] In FIG. 6a, the horizontal axis of the chart (610) represents time. On the vertical axis of the chart (610), the waveform (601) represents the CPU load of the central unit (CU) (410). On the vertical axis of the chart (610), the waveform (602) represents the overload level. For example, the overload level may be normal (651), minor (652), major (653), or critical (654). In one example, if the CPU load is less than or equal to a first value (611), the overload level may be normal (651). In one example, if the CPU load exceeds the first value (611) and is less than or equal to a second value (612), the overload level may be minor (652). In one example, if the CPU load exceeds the second value (612) and is less than or equal to the third value (613), the overload rating may be major (653). In one example, if the CPU load exceeds the third value (613), the overload rating may be critical (654).

[0096] Referring to FIG. 6a, at time (621), the CPU load may exceed a first value (611). Since the CPU load exceeds the first value (611), the CU (410) may trigger a unified access control (UAC) miner. The CU (410) may send a network access rate reduction message corresponding to the UAC miner to the DU (420). At time (631), the DU (420) may send a system information block (SIB) 1, which includes a UAC barring factor and a UAC barring time corresponding to the UAC miner, to the user equipment (UE) (120). A delay (606) may occur between the time (621) when the UAC miner is triggered and the time (631) when the UAC barring parameters corresponding to the UAC miner are applied.

[0097] At time (622), the CPU load may exceed the second value (612). Since the CPU load exceeds the second value (612), the CU (410) may trigger a UAC major. The CU (410) may send a network connection rate reduction message corresponding to the UAC major to the DU (420). At time (632), the DU (420) may send SIB1, which includes a UAC barring factor and a UAC barring time corresponding to the UAC major, to the UE (120). A delay may occur between the time (622) when the UAC major is triggered and the time (632) when the UAC barring parameters corresponding to the UAC major are applied.

[0098] At time (623), the CPU load may exceed the third value (613). Since the CPU load exceeds the third value (613), the CU (410) may trigger a UAC critical. The CU (410) may send a network connection rate reduction message corresponding to the UAC critical to the DU (420). At time (633), the DU (420) may send SIB1, which includes a UAC barring factor and a UAC barring time corresponding to the UAC critical, to the UE (120). Additionally, the CU (410) may perform call admission control (CAC) when the CPU load exceeds the third value (613). For example, the CU (410) may receive a radio resource control (RRC) connection request message from a UE in an RRC idle state. CU (410) may, depending on the CAC, send a reject message to the UE and / or ignore the UE's RRC connection request message. Therefore, a call reject may occur during the time interval (607).

[0099] At time (624), the CPU load may be less than the first value (611). Since the CPU load is less than or equal to the first value (611), the CU (410) may trigger a UAC clear. The CU (410) may send a network connection rate reduction message corresponding to the UAC clear to the DU (420). At time (634), the DU (420) may send a SIB1 to the UE (120) that includes a UAC barring factor and a UAC barring time corresponding to the UAC clear. In an example that is not limited, when the UAC clear is triggered, the SIB1 may not include a UAC barring factor and a UAC barring time.

[0100] As described above, a delay may occur after UAC control is triggered until the SIB1 corresponding to the UAC control is transmitted. This delay may correspond to a 2*MP (modification period). The first MP among the 2*MPs may be the time interval required for the CU (410) to generate a network connection rate reduction message corresponding to the UAC control and then transmit the message to the DU (420). The second MP among the 2*MPs may be the time interval required for the DU (420) to generate UAC barring parameters corresponding to the UAC control and then transmit the SIB1 containing those parameters to the UE (120).

[0101] As described in FIG. 6a, the CU (410) can perform overload control (e.g., UAC control and / or CAC control) after entering an overload state. However, there may be a delay between the time the overload control is triggered and the time the overload control is applied. This delay may not effectively reduce the CPU load of the CU (410). Since the method described in FIG. 6a does not effectively reduce the CPU load of the CU (410), call rejection may occur during a specific time interval (e.g., time interval (607)).

[0102] FIG. 6b illustrates a chart showing the load according to overload control. FIG. 6b explains an example of an implementation of overload control based on dynamic spectrum sharing (DSS) radio resource control (RRC) load. To provide DSS, new radio (NR) base stations and long term evolution (LTE) base stations may be used.

[0103] In the example of FIG. 6b, DSS can be performed by an LTE base station and an NR base station. When DSS is performed, an LTE cell and an NR cell can be paired to share the radio resources of the corresponding carrier. For example, LTE resources and NR resources can be dynamically allocated on an hourly basis in the same frequency band. Therefore, in order to dynamically allocate limited radio resources, in addition to the maximum capacity of the UE (user equipment) of the LTE cell and the maximum capacity of the UE of the NR cell, the DSS RRC load in the paired LTE-NR combined cell may be constrained. For example, if the DSS RRC load exceeds the combined UE capacity (681), the base station (e.g., LTE base station and / or NR base station) may reject new calls based on call admission control (CAC).

[0104] In FIG. 6b, the horizontal axis of the chart (660) represents time. For example, on the vertical axis of the chart (660), waveform (661) represents the NR load. The NR load may correspond to the number of UEs connected to the NR base station. For example, on the vertical axis of the chart (660), waveform (662) represents the LTE load. The LTE load may correspond to the number of UEs connected to the LTE base station. For example, on the vertical axis of the chart (660), waveform (663) represents the DSS load. The DSS load may correspond to the summation of the number of UEs connected to the NR base station and the number of UEs connected to the LTE base station.

[0105] Referring to FIG. 6b, the load of an LTE cell may increase. Even if the load of an LTE cell increases, if the DSS load is less than the combined UE capacity (681) in an LTE-NR cell, the NR cell with a relatively lower load can continue to receive and process new calls. Therefore, while the NR cell processes new calls, the DSS load and / or LTE load may continue to increase. In the time interval (671), as the load increases, the DSS load may exceed the combined UE capacity (681). Since the DSS load exceeds the combined UE capacity (681), the base station (e.g., LTE base station and NR base station) may reject new calls based on CAC. For example, since the DSS load exceeds the combined UE capacity (681), the base station may send an RRC rejection message for an RRC connection request message obtained from a UE (120) or ignore the RRC connection request message. The UE (120) may repeatedly send RRC connection request messages until it receives an RRC rejection message or until a call attempt is successful. Therefore, the load on the LTE cell and / or NR cell may increase due to repeated RRC connection request messages. As a result, additional call rejects may occur in time interval (672), time interval (673), and time interval (674).

[0106] As described in FIGS. 5a through 6b, in the 3GPP (3rd generation partnership project) and implementations for overload control, the DU (distributed unit) (420) performs overload control in an event-triggered manner. For example, the DU (420) performs overload control after an overload of the AMF (access and mobility management function) (520), an overload of the CU (central unit) (410), and / or a DSS (dynamic spectrum sharing) overload occurs. Therefore, since overload control is performed after the system has already entered an overload state, call rejections due to CAC (call admission control) may occur frequently. Since call rejections occur frequently, the user experience of receiving communication services may be degraded. To solve the aforementioned problems, it is necessary to perform proactive overload control based on load information of the CU and / or load information of the eNB (eNodeB). Below, an apparatus and method for performing proactive overload control based on load information of the CU and / or load information of the eNB are described.

[0107] FIG. 7 illustrates an example of signaling for exchanging information for overload control. The operations of FIG. 7 may be performed by a DU (distributed unit) (420). For example, at least some of the operations may be controlled by a processor (450) of the DU (420). In the following, each operation may be performed sequentially, but is not necessarily performed sequentially. For example, the order of each operation may be changed and / or at least two operations may be performed in parallel.

[0108] FIG. 7 illustrates a central unit (CU) (410), a DU (420), and a base station (710) for providing dynamic spectrum sharing (DSS). The base station (710) may be an eNB (eNodeB) that supports LTE. However, the present disclosure is not limited thereto. In the following, the CU (410) and the DU (420) may be replaced with entities that support a first radio access technology (RAT), and the base station (710) may be replaced with entities that support a second RAT that is different from the first RAT.

[0109] Referring to FIG. 7, in operation 701, a DU (420) according to one embodiment may receive (or obtain) central unit (CU) load information from a CU (410). For example, the CU (410) may periodically transmit (or provide) the CU load information to the DU (420). In another example, the CU (410) may transmit (or provide) the CU load information to the DU (420) when the CU load included in the CU load information changes by more than a threshold value during a predefined time interval. In one example, the CU load information may be referred to as F1AP (F1 application protocol) gNB (gNodeB)-CU load information or other terms having an equivalent technical / functional meaning.

[0110] In one embodiment, the CU load information may include a message type, a transaction ID (identifier), and / or a CU load list. For example, the message type may be used to uniquely identify a message containing the CU load information. For example, the transaction ID may be used to uniquely identify a procedure among all ongoing parallel procedures of the same type initiated by the same protocol peer.

[0111] In one embodiment, the CU load list may include load information of a first type and load information of a second type.

[0112] In one embodiment, the load information of the first load type may represent the CPU (central processing unit) load of the CU (410). In one example, the CPU load may be the utilization of at least one CPU of the CU (410). However, this is merely an example and the present disclosure is not limited thereto. For example, the CPU load may be the sum of the number of processes running on at least one CPU of the CU (410) and the number of processes waiting on at least one CPU of the CU (410).

[0113] In one embodiment, the load information of the second load type may represent the radio resource control (RRC) load of the CU (410). In one example, the RRC load may be a ratio between the number of UEs connected to cells provided by the CU (410) and the maximum number of UEs that can be connected to the CU (410). However, this is merely an example and the present disclosure is not limited thereto. For example, the RRC load may be the number of RRC connection request messages per unit time received by the CU (410). In another example, the RRC load may be the number of RRC rejection messages per unit time transmitted by the CU (410).

[0114] In one example, the CU load information may be as shown in Table 1 below.

[0115]

[0116] In Table 1, Message Type indicates the message type of the CU load information. Transaction ID indicates the transaction ID of the CU load information. gNB-CU Load may include a CU load list. In one example, the CU load list may be referred to as the gNB-CU Load List. In one example, the gNB-CU Load List may be as shown in Table 2 below.

[0117]

[0118] In Table 2, the gNB-CU Load Type Item indicates the load type. For example, the gNB-CU Load Type Item may indicate either the first type or the second type. gNB-CU Load indicates the value of the CU load. For example, gNB-CU Load may indicate the value of the CPU load or the value of the RRC load. Additional Information indicates additional information included in the CU load information.

[0119] In operation 702, a DU (420) according to one embodiment may receive (or obtain) LTE (long term evolution) load information from a base station (710). For example, the base station (710) may periodically transmit (or provide) the LTE load information to the DU (420). In another example, the base station (710) may transmit (or provide) the LTE load information to the DU (420) when the LTE load included in the LTE load information changes by more than a threshold value during a predefined time interval. In one example, the LTE load information may be referred to as X2AP (X2 application protocol) LTE load information or other terms having an equivalent technical / functional meaning.

[0120] In one embodiment, LTE load information may include a message type, a transaction ID, and / or an LTE load list. For example, the message type may be used to uniquely identify a message containing LTE load information. For example, the transaction ID may be used to uniquely identify a procedure among all ongoing parallel procedures of the same type initiated by the same protocol peer.

[0121] In one embodiment, the LTE load list may include load information of a third type and load information of a fourth type.

[0122] In one embodiment, the third type of load information may represent the CPU load of the base station (710). In one example, the CPU load may be the utilization of at least one CPU of the base station (710). However, this is merely an example and the present disclosure is not limited thereto. For example, the CPU load may be the sum of the number of processes running on at least one CPU of the base station (710) and the number of processes waiting on at least one CPU of the base station (710).

[0123] In one embodiment, the load information of the fourth type may be the RRC load of the base station (710). In one example, the RRC load may be the ratio between the number of UEs connected to cells provided by the base station (710) and the maximum number of UEs that can be connected to the base station (710). However, this is merely an example and the present disclosure is not limited thereto. For example, the RRC load may be the number of RRC connection request messages per unit time received by the base station (710). In another example, the RRC load may be the number of RRC rejection messages per unit time transmitted by the base station (710).

[0124] In one example, LTE load information may be as shown in Table 3 below.

[0125]

[0126] In Table 3, Message Type indicates the message type of the LTE load information. Transaction ID indicates the transaction ID of the LTE load information. LTE eNB Load may include an LTE load list. In one example, the LTE load list may be referred to as the eNB Load List. In one example, the eNB Load List may be as shown in Table 4 below.

[0127]

[0128] In Table 4, the eNB Load Type Item indicates the load type. For example, the eNB Load Type Item may indicate either the third type or the fourth type. eNB Load indicates the value of the LTE load. For example, eNB Load may indicate the value of the CPU load or the value of the RRC load. Additional Information indicates additional information included in the LTE load information.

[0129] In operation 703, a DU (420) according to one embodiment may transmit (or provide) NR (new radio) load information to a base station (710). For example, the DU (420) may periodically transmit (or provide) NR load information to the base station (710). In another example, the DU (420) may transmit (or provide) NR load information to the base station (710) when the NR load included in the NR load information changes by more than a threshold value during a predefined time interval. In one example, the NR load information may be referred to as X2AP gNB-load information or other terms having an equivalent technical / functional meaning.

[0130] In one embodiment, the NR load information may include a message type, a transaction ID, and / or an NR load list. For example, the message type may be used to uniquely identify a message containing the NR load information. For example, the transaction ID may be used to uniquely identify a procedure among all ongoing parallel procedures of the same type initiated by the same protocol peer.

[0131] In one embodiment, the NR load list may include load information of a fifth type and load information of a sixth type.

[0132] In one embodiment, the load information of the fifth load type may represent the CPU load of the DU (420). In one example, the CPU load may be the utilization rate of at least one CPU of the DU (420). However, this is merely an example and the present disclosure is not limited thereto. For example, the CPU load may be the sum of the number of processes running on at least one CPU of the DU (420) and the number of processes waiting on at least one CPU of the DU (420).

[0133] In one embodiment, the load information of the sixth type may represent the RRC load of the DU (420). In one example, the RRC load may be the ratio between the number of UEs connected to the cells provided by the DU (420) and the maximum number of UEs that can be connected to the DU (420). However, this is merely an example and the present disclosure is not limited thereto. For example, the RRC load may be the number of RRC connection request messages per unit time received by the DU (420). In another example, the RRC load may be the number of RRC rejection messages per unit time transmitted by the DU (420).

[0134] In one example, the NR load information may be as shown in Table 5 below.

[0135]

[0136] In Table 5, Message Type indicates the message type of the NR load information. Transaction ID indicates the transaction ID of the NR load information. gNB-DU Load may include an NR load list. In one example, the LTE load list may be referred to as the gNB-DU Load List. In one example, the gNB-DU Load List may be as shown in Table 6 below.

[0137]

[0138] In Table 6, gNB-DU Load Type indicates the load type. For example, gNB-DU Load Type may represent either Type 5 or Type 6. gNB-DU Load indicates the value of the DU load. For example, gNB-DU Load may represent the value of the CPU load or the value of the RRC load. Additional Information indicates additional information included in the LTE load information.

[0139] FIG. 8 illustrates a flowchart showing the operations of a DU for overload control. The operations of FIG. 8 can be performed by a DU (distributed unit) (420). For example, at least some of the operations can be controlled by a processor (450) of the DU (420). In the following, each operation may be performed sequentially, but is not necessarily performed sequentially. For example, the order of each operation may be changed and / or at least two operations may be performed in parallel.

[0140] Referring to FIG. 8, in operation 801, a DU (420) according to one embodiment can obtain load information. For example, the load information may include CU (central unit) load information and / or LTE (long term evolution) load information.

[0141] In one embodiment, the DU (420) may receive (or obtain) CU load information from the CU (410). For example, the CU (410) may periodically transmit (or provide) CU load information to the DU (420). In another embodiment, the CU (410) may transmit (or provide) CU load information to the DU (420) when the CU load changes above a threshold value during a predefined time interval. In one example, the CU load information may be referred to as F1AP (F1 application protocol) gNB (gNodeB)-CU load information or other terms having an equivalent technical / functional meaning.

[0142] For example, CU load information may include a load list. For example, the load list may include load information of a first type and load information of a second type.

[0143] For example, the load information of the first type may represent the CPU (central processing unit) load of the CU (410). In one example, the CPU load may be the utilization of at least one CPU of the CU (410). However, this is merely an example and the present disclosure is not limited thereto. For example, the CPU load may be the sum of the number of processes running on at least one CPU of the CU (410) and the number of processes waiting on at least one CPU of the CU (410).

[0144] For example, the second type of load information may represent the radio resource control (RRC) load of the CU (410). In one example, the RRC load may be a ratio between the number of UEs connected to cells provided by the CU (410) and the maximum number of UEs that can be connected to the CU (410). However, this is merely an example and the present disclosure is not limited thereto. For example, the RRC load may be the number of RRC connection request messages per unit time received by the CU (410). In another example, the RRC load may be the number of RRC rejection messages per unit time transmitted by the CU (410).

[0145] In one embodiment, the DU (420) may receive (or obtain) LTE load information from the base station (710). For example, the base station (710) may periodically transmit (or provide) the LTE load information to the DU (420). In another embodiment, the base station (710) may transmit (or provide) the LTE load information to the DU (420) when the LTE load included in the LTE load information changes by more than a threshold value during a predefined time interval. In one embodiment, the LTE load information may be referred to as X2AP (X2 application protocol) LTE load information or other terms having an equivalent technical / functional meaning.

[0146] For example, LTE load information may include a load list. For example, the load list may include load information of a third type and load information of a fourth type.

[0147] For example, the load information of the third type may represent the CPU load of the base station (710). In one example, the CPU load may be the utilization of at least one CPU of the base station (710). However, this is merely an example and the present disclosure is not limited thereto. For example, the CPU load may be the sum of the number of processes running on at least one CPU of the base station (710) and the number of processes waiting on at least one CPU of the base station (710).

[0148] For example, the load information of the fourth type may represent the RRC load of the base station (710). In one example, the RRC load may be the ratio between the number of UEs connected to cells provided by the base station (710) and the maximum number of UEs that can be connected to the base station (710). However, this is merely an example and the present disclosure is not limited thereto. For example, the RRC load may be the number of RRC connection request messages per unit time received by the base station (710). In another example, the RRC load may be the number of RRC rejection messages per unit time transmitted by the base station (710).

[0149] In operation 802, the DU (420) according to one embodiment can obtain (or determine) UAC barring parameters based on load information.

[0150] In one embodiment, the DU (420) can identify a load based on load information. For example, the load identified based on load information may be one of the CPU (central processing unit) load of the CU (410), the RRC (radio resource control) load of the CU (410), the CPU load of the base station (710), or the DSS (dynamic spectrum sharing) RRC load. In one example, the relationship between the load information and the load may be as shown in Table 7 below.

[0151] Load information Load Type 1 load information CPU load of CU (410) Load Type 2 load information RRC load of CU (410) Load Type 3 load information CPU load of base station (710) Load information of Type 2 and Load information of Type 4 DSS RRC load

[0152] For example, a DSS RRC load can be identified based on Type 2 load information and Type 4 load information. In one example, a DSS RRC load can be identified according to Equation 3 below.

[0153]

[0154] In Equation 3, the DSS RRC Load is the DSS RRC load. The number of connected UEs in an LTE cell is the number of UEs connected to cells provided by the base station (710). For example, the number of connected UEs in an LTE cell can be identified based on LTE load information obtained from the base station (710). The number of connected UEs in an NR cell is the number of UEs connected to cells provided by the CU (410). For example, the number of connected UEs in an NR cell can be identified based on CU load information obtained from the CU (410). The maximum number of DSS UEs may correspond to the sum of the maximum number of UEs connectable to the base station (710) and the maximum number of UEs connectable to the CU (410). Equation 3 describes identifying the DSS RRC Load based on the number of UEs connected to entities, but this is merely an example and the present disclosure is not limited thereto. For example, the DSS RRC Load may be identified based on the number of RRC connection request messages per unit time received by the base station (710), the number of RRC connection request messages per unit time received by the CU (410), and the maximum number of RRC connection request messages allowed for the base station (710) and the CU (410). In another example, the DSS RRC Load may be identified based on the number of RRC rejection messages per unit time transmitted by the base station (710), the number of RRC rejection messages per unit time transmitted by the CU (410), and the maximum number of RRC rejection messages allowed for the base station (710) and the CU (410).

[0155] In one embodiment, the DU (420) can identify a unified access control (UAC) state. For example, the UAC state may be one of a normal load state (e.g., normal load state (910) of FIG. 9), a first overload state (e.g., first overload state (920) of FIG. 9), or a second overload state (e.g., second overload state (930) of FIG. 9).

[0156] In one embodiment, the DU (420) in a normal load state can determine a UAC state (e.g., normal load state, first overload state, or second overload state) based on the load. The DU (420) can determine UAC barring parameters based on the determined UAC state and / or load. In this regard, the descriptions of FIGS. 9 and FIGS. 10 may be referenced.

[0157] In one embodiment, the DU (420) in a first overload state may determine the UAC state based on the load. The DU (420) may determine UAC barring parameters based on the determined UAC state and / or load. In this regard, the descriptions of FIGS. 9 and FIGS. 11 may be referenced.

[0158] In one embodiment, the DU (420) in a second overload state may determine the UAC state based on the load. The DU (420) may determine UAC barring parameters based on the determined UAC state and / or load. In this regard, the descriptions of FIGS. 9 and FIGS. 12 may be referenced.

[0159] In operation 803, a DU (420) according to one embodiment may transmit a system information block (SIB) containing UAC barring parameters to a user equipment (UE) (120). For example, the UAC barring parameters may include a UAC barring factor and a UAC barring time. For example, the SIB may be SIB1.

[0160] Figure 9 illustrates examples of UAC states of a DU for overload control.

[0161] Referring to FIG. 9, UAC states may include a normal load state (910), a first overload state (920), and / or a second overload state (930). In one example, the first overload state (920) may be referred to as a low overload state, and the second overload state (930) may be referred to as a high overload state.

[0162] For example, operations performed by the DU (distributed unit) (420) in a normal load state (910) are described in FIG. 10. Operations performed by the DU (420) in a first overload state (920) are described in FIG. 11. Operations performed by the DU (420) in a second overload state (930) are described in FIG. 12. Below, a state transition between the normal load state (910), the first overload state (920), and the second overload state (930) is described.

[0163] In one embodiment, the DU (420) can obtain load information. For example, the load information may include CU (central unit) load information and / or LTE (long term evolution) load information. For example, CU load information may be obtained from the CU (410). For example, LTE load information may be obtained from the base station (710).

[0164] In one embodiment, the DU (420) can identify a load based on load information. For example, the load identified based on load information may be the CPU (central processing unit) load of the CU (410), the RRC (radio resource control) load of the CU (410), the CPU load of the base station (710), or the DSS (dynamic spectrum sharing) RRC load.

[0165] Referring to the normal load state (910) of FIG. 9, the DU (420) can determine whether the load identified by the load information exceeds a first threshold value while operating in the normal load state (910). For example, the first threshold value may be a value predefined for transitioning between the normal load state (910) and the first overload state (910). In one example, the first threshold value may be referred to as threshold-low-overload or other terms having an equivalent technical / functional meaning.

[0166] For example, referring to state change (911), the DU (420) may change the UAC state from the normal load state (910) to the first overload state (920) based on a determination that the load exceeds the first threshold while operating in the normal load state (910). In another example, the DU (420) may maintain the UAC state in the normal load state (910) based on a determination that the load is below the first threshold while operating in the normal load state (910). In an example not limited to, referring to state change (912), the DU (420) may change the UAC state from the normal load state (910) to the second overload state (930) based on a determination that the load exceeds the second threshold while operating in the normal load state (910). The second threshold value may be a value predefined for transitioning between the first overload state (920) and the second overload state (930). In one example, the second threshold value may be referred to as threshold-high-overload or other terms having an equivalent technical / functional meaning.

[0167] Referring to the first overload state (920) of FIG. 9, the DU (420) can identify the load based on load information while operating in the first overload state (920). For example, referring to the state change (921), the DU (420) can change the UAC state from the first overload state (920) to the normal load state (910) based on the determination that the load is below the first threshold value while operating in the first overload state (910). For example, referring to the state change (922), the DU (420) can change the UAC state from the first overload state (920) to the second overload state (930) based on the determination that the load exceeds the second threshold value while operating in the first overload state (910). For example, the DU (420) can maintain the UAC state in the first overload state (910) based on the determination that the load is between the first threshold value and the second threshold value while operating in the first overload state (910).

[0168] Referring to the second overload state (930) of FIG. 9, the DU (420) can identify the load based on load information while operating in the second overload state (930). For example, referring to the state change (931), the DU (420) can change the UAC state from the second overload state (930) to the first overload state (920) based on the determination that the load is below the second threshold value while operating in the second overload state (930). For example, the DU (420) can maintain the UAC state in the second overload state (930) based on the determination that the load exceeds the second threshold value while operating in the second overload state (930). In a non-limiting example, the DU (420) can change the UAC state from the second overload state (930) to the normal load state (910) based on the determination that the load is below the first threshold value while operating in the second overload state (930).

[0169] FIG. 10 is a flowchart illustrating the operations of a DU under normal load conditions. The operations of FIG. 10 can be performed by a DU (distributed unit) (420). For example, at least some of the operations can be controlled by a processor (450) of the DU (420). In the following, each operation may be performed sequentially, but is not necessarily performed sequentially. For example, the order of each operation may be changed and / or at least two operations may be performed in parallel.

[0170] Referring to FIG. 10, in operation 1001, a DU (420) according to one embodiment can acquire load information while operating under normal load conditions. For example, the load information may include CU (central unit) load information and / or LTE (long term evolution) load information.

[0171] In one embodiment, the DU (420) may receive (or obtain) CU load information from the CU (410) while operating under normal load conditions. For example, the CU (410) may periodically transmit (or provide) CU load information to the DU (420). In another example, the CU (410) may transmit (or provide) CU load information to the DU (420) when the CU load changes above a threshold value during a predefined time interval. In one example, CU load information may be referred to as F1AP (F1 application protocol) gNB (gNodeB)-CU load information or other terms having an equivalent technical / functional meaning.

[0172] For example, CU load information may include a load list. For example, the load list may include load information of a first type and / or load information of a second type.

[0173] For example, the load information of the first type may represent the CPU (central processing unit) load of the CU (410). In one example, the CPU load may be the utilization of at least one CPU of the CU (410). However, this is merely an example and the present disclosure is not limited thereto. For example, the CPU load may be the sum of the number of processes running on at least one CPU of the CU (410) and the number of processes waiting on at least one CPU of the CU (410).

[0174] For example, the second type of load information may represent the radio resource control (RRC) load of the CU (410). In one example, the RRC load may be a ratio between the number of UEs connected to cells provided by the CU (410) and the maximum number of UEs that can be connected to the CU (410). However, this is merely an example and the present disclosure is not limited thereto. For example, the RRC load may be the number of RRC connection request messages per unit time received by the CU (410). In another example, the RRC load may be the number of RRC rejection messages per unit time transmitted by the CU (410).

[0175] In one embodiment, the DU (420) may receive (or obtain) LTE load information from the base station (710) while operating under normal load conditions. For example, the base station (710) may periodically transmit (or provide) the LTE load information to the DU (420). In another example, the base station (710) may transmit (or provide) the LTE load information to the DU (420) when the LTE load included in the LTE load information changes by more than a threshold value during a predefined time interval. In one example, the LTE load information may be referred to as X2AP (X2 application protocol) LTE load information or other terms having an equivalent technical / functional meaning.

[0176] For example, LTE load information may include a load list. For example, the load list may include load information of a third type and / or load information of a fourth type.

[0177] For example, the load information of the third type may represent the CPU load of the base station (710). In one example, the CPU load may be the utilization of at least one CPU of the base station (710). However, this is merely an example and the present disclosure is not limited thereto. For example, the CPU load may be the sum of the number of processes running on at least one CPU of the base station (710) and the number of processes waiting on at least one CPU of the base station (710).

[0178] For example, the load information of the fourth type may be the RRC load of the base station (710). In one example, the RRC load may be the ratio between the number of UEs connected to cells provided by the base station (710) and the maximum number of UEs that can be connected to the base station (710). However, this is merely an example and the present disclosure is not limited thereto. For example, the RRC load may be the number of RRC connection request messages per unit time received by the base station (710). In another example, the RRC load may be the number of RRC rejection messages per unit time transmitted by the base station (710).

[0179] In operation 1002, the DU (420) according to one embodiment can identify a load based on load information. For example, the load identified based on load information may be the CPU load of the CU (410), the RRC load of the CU (410), the CPU load of the base station (710), or the DSS (dynamic spectrum sharing) RRC load. For example, the CPU load of the CU (410) may be identified based on a first type of load information. For example, the RRC load of the CU (410) may be identified based on a second type of load information. For example, the CPU load of the base station (710) may be identified based on a third type of load information. For example, the DSS RRC load may be identified based on a second type of load information and a fourth type of load information. For a description of the DSS RRC load, the above-described Equation 3 and the description of Equation 3 may be referenced.

[0180] In operation 1003, the DU (420) according to one embodiment may determine whether the load exceeds a first threshold value. For example, the first threshold value may be a value predefined for transitioning between a normal load state and a first overload state. In one example, the first threshold value may be referred to as threshold-low-overload or other terms having an equivalent technical / functional meaning.

[0181] In operation 1004, the DU (420) according to one embodiment may determine unified access control (UAC) barring parameters having a least restrictive level upon determining that the load exceeds a first threshold value. For example, the least restrictive level may mean the level with the least restriction among the levels predefined for UAC.

[0182] For example, UAC barring parameters may include a UAC barring factor and / or a UAC barring time. The UAC barring factor may indicate the probability that an access attempt will be allowed during an access barring check. The UAC barring time may indicate the average time from when an access attempt is barred until a new access attempt is performed during an access barring check for the same access category.

[0183] For example, the DU (420) may change the UAC state from a normal load state to a first overload state upon determining that the load exceeds a first threshold value. In response to entering the first overload state, the DU (420) may determine a UAC barring factor having a minimum regulation level (e.g., 0.95) among predefined first levels (e.g., 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.30, 0.40, 0.50, 0.60, 0.70, 0.75, 0.80, 0.85, 0.90, and 0.95). That is, the UAC barring factor having the minimum regulation level may have a maximum value among the predefined values ​​for the UAC barring factor. For example, the DU (420) can determine a UAC barring time having a minimum regulation level (e.g., 4 seconds) among predefined second levels (e.g., 4 seconds, 8 seconds, 16 seconds, 32 seconds, 64 seconds, 128 seconds, 256 seconds, and 512 seconds) in response to entering a first overload state. That is, the UAC barring time having the minimum regulation level may have a minimum value among the predefined values ​​for UAC barring time. The level used in the following description may be referred to as a value or other term having an equivalent technical / functional meaning.

[0184] In the example described above, the UE (120) can identify that the access attempt is permitted if the random number is less than or equal to the value indicated by the UAC barring factor (e.g., 0.95). Alternatively, the UE (120) can identify that the access attempt is barred if the random number exceeds the value indicated by the UAC barring factor (e.g., 0.95). Additionally, if the access attempt is barred, the UE (120) can wait for a timer determined based on the value indicated by the UAC barring time (e.g., 4 seconds).

[0185] In operation 1005, the DU (420) according to one embodiment may refrain from performing UAC barring based on a determination that the load is below a first threshold value. For example, the DU (420) may maintain the UAC state in a normal load state based on a determination that the load is below a first threshold value. The DU (420) may refrain from performing UAC barring in the normal load state. For example, the DU (420) may refrain from determining UAC barring parameters (e.g., UAC barring factor and UAC barring time) in the normal load state.

[0186] In operation 1006, a DU (420) according to one embodiment may transmit a system information block (SIB) to a UE (120). For example, the SIB may be SIB1. For example, in a first overload condition, SIB1 may include UAC barring parameters (e.g., UAC barring factor and UAC barring time). In another example, in a normal load condition, SIB1 may not include UAC barring parameters.

[0187] FIG. 11 is a flowchart illustrating the operations of a DU in a first overload state. The operations of FIG. 11 may be performed by a DU (distributed unit) (420). For example, at least some of the operations may be controlled by a processor (450) of the DU (420). In the following, each operation may be performed sequentially, but is not necessarily performed sequentially. For example, the order of each operation may be changed and / or at least two operations may be performed in parallel.

[0188] Referring to FIG. 11, in operation 1101, a DU (420) according to one embodiment can acquire load information while operating in a first overload state. For example, the load information may include CU (central unit) load information and / or LTE (long term evolution) load information.

[0189] In one embodiment, the DU (420) may receive (or obtain) CU load information from the CU (central unit) (410) while operating in a first overload state. For example, the CU (410) may periodically transmit (or provide) the CU load information to the DU (420). In another example, the CU (410) may transmit (or provide) the CU load information to the DU (420) when the CU load changes above a threshold value during a predefined time interval. In one example, the CU load information may be referred to as F1AP (F1 application protocol) gNB (gNodeB)-CU load information or other terms having an equivalent technical / functional meaning.

[0190] For example, CU load information may include a load list. For example, the load list may include load information of a first type and / or load information of a second type.

[0191] For example, the load information of the first type may represent the CPU (central processing unit) load of the CU (410). In one example, the CPU load may be the utilization of at least one CPU of the CU (410). However, this is merely an example and the present disclosure is not limited thereto. For example, the CPU load may be the sum of the number of processes running on at least one CPU of the CU (410) and the number of processes waiting on at least one CPU of the CU (410).

[0192] For example, the second type of load information may represent the radio resource control (RRC) load of the CU (410). In one example, the RRC load may be a ratio between the number of UEs connected to cells provided by the CU (410) and the maximum number of UEs that can be connected to the CU (410). However, this is merely an example and the present disclosure is not limited thereto. For example, the RRC load may be the number of RRC connection request messages per unit time received by the CU (410). In another example, the RRC load may be the number of RRC rejection messages per unit time transmitted by the CU (410).

[0193] In one embodiment, the DU (420) may receive (or obtain) LTE load information from the base station (710) while operating in a first overload state. For example, the base station (710) may periodically transmit (or provide) the LTE load information to the DU (420). In another example, the base station (710) may transmit (or provide) the LTE load information to the DU (420) when the LTE load included in the LTE load information changes by more than a threshold value during a predefined time interval. In one example, the LTE load information may be referred to as X2AP (X2 application protocol) LTE load information or other terms having an equivalent technical / functional meaning.

[0194] For example, LTE load information may include a load list. For example, the load list may include load information of a third type and / or load information of a fourth type.

[0195] For example, the load information of the third type may be the CPU load of the base station (710). In one example, the CPU load may be the utilization of at least one CPU of the base station (710). However, this is merely an example and the present disclosure is not limited thereto. For example, the CPU load may be the sum of the number of processes running on at least one CPU of the base station (710) and the number of processes waiting on at least one CPU of the base station (710).

[0196] For example, the load information of the fourth type may represent the RRC load of the base station (710). In one example, the RRC load may be the ratio between the number of UEs connected to cells provided by the base station (710) and the maximum number of UEs that can be connected to the base station (710). However, this is merely an example and the present disclosure is not limited thereto. For example, the RRC load may be the number of RRC connection request messages per unit time received by the base station (710). In another example, the RRC load may be the number of RRC rejection messages per unit time transmitted by the base station (710).

[0197] In operation 1102, the DU (420) according to one embodiment can identify a load based on load information. For example, the load identified based on load information may be the CPU load of the CU (410), the RRC load of the CU (410), the CPU load of the base station (710), or the DSS (dynamic spectrum sharing) RRC load. For example, the CPU load of the CU (410) may be identified based on a first type of load information. For example, the RRC load of the CU (410) may be identified based on a second type of load information. For example, the CPU load of the base station (710) may be identified based on a third type of load information. For example, the DSS RRC load may be identified based on a second type of load information and a fourth type of load information. For a description of the DSS RRC load, the above-described Equation 3 and the description of Equation 3 may be referenced.

[0198] In operation 1103, the DU (420) according to one embodiment may determine whether the load exceeds a second threshold value. For example, the second threshold value may be a value predefined for transitioning between a first overload state and a second overload state. In one example, the second threshold value may be referred to as threshold-high-overload or other terms having an equivalent technical / functional meaning.

[0199] In operation 1104, the DU (420) according to one embodiment may determine unified access control (UAC) barring parameters having a most restrictive level upon determining that the load exceeds a second threshold value. For example, the most restrictive level may mean the level with the greatest restriction among the levels predefined for UAC.

[0200] For example, UAC barring parameters may include a UAC barring factor and / or a UAC barring time. The UAC barring factor may indicate the probability that an access attempt will be allowed during an access barring check. The UAC barring time may indicate the average time from when an access attempt is barred until a new access attempt is performed during an access barring check for the same access category.

[0201] For example, the DU (420) may change the UAC state from a first overload state to a second overload state upon determining that the load exceeds a second threshold value. In response to entering the second overload state, the DU (420) may determine a UAC barring factor having a maximum regulation level (e.g., 0.0 or 0.05) among predefined first levels (e.g., 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.30, 0.40, 0.50, 0.60, 0.70, 0.75, 0.80, 0.85, 0.90, and 0.95). That is, the UAC barring factor having the maximum regulation level may have a minimum value among the predefined values ​​for the UAC barring factor. For example, the DU (420) can determine a UAC barring time having a maximum regulation level (e.g., 512 seconds) among predefined second levels (e.g., 4 seconds, 8 seconds, 16 seconds, 32 seconds, 64 seconds, 128 seconds, 256 seconds, and 512 seconds) in response to entering a second overload state. That is, the UAC barring time having the maximum regulation level can have a maximum value among the predefined values ​​for the UAC barring time.

[0202] In the example described above, since the random number exceeds the value indicated by the UAC barring factor (e.g., 0.0), the UE (120) can identify that the access attempt is barred. The UE (120) can wait for a timer determined based on the value indicated by the UAC barring time (e.g., 512 seconds).

[0203] In operation 1105, the DU (420) according to one embodiment may determine whether the load is below a first threshold value based on the determination that the load is below a second threshold value. For example, the first threshold value may be a value predefined for transitioning between a normal load state and a first overload state. In one example, the first threshold value may be referred to as threshold-low-overload or other terms having an equivalent technical / functional meaning.

[0204] In operation 1106, the DU (420) according to one embodiment may refrain from performing UAC barring upon determining that the load is below a first threshold value. For example, the DU (420) may change the UAC state from a first overload state to a normal load state upon determining that the load is below a first threshold value. The DU (420) may refrain from performing UAC barring in response to entering the normal load state.

[0205] In operation 1107, the DU (420) according to one embodiment may determine whether the load exceeds a first value based on the determination that the load exceeds a first threshold value. For example, the first value may be the value obtained by adding an offset value (or alpha) to the prior load. In one example, operation 1107 may be expressed according to Equation 4 below.

[0206]

[0207] In Equation 4, Current Load is the load identified based on load information. Prior Load is the load identified based on load information from the previous cycle. The offset value is a predefined offset value.

[0208] In operation 1108, the DU (420) according to one embodiment can determine UAC barring parameters having a regulation level following the current regulation level based on the determination that the load exceeds a first value.

[0209] For example, the DU (420) can determine a UAC barring factor having a level (e.g., 0.40) that precedes the current level (e.g., 0.50) among predefined first levels (e.g., 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.30, 0.40, 0.50, 0.60, 0.70, 0.75, 0.80, 0.85, 0.90, and 0.95) based on the determination that the load exceeds a first value. That is, since the regulation of the UAC barring factor increases as the value decreases, the DU (420) can determine a UAC barring factor having a value smaller than the current value. For example, the DU (420) can determine a UAC barring time for a level (e.g., 64 seconds) that follows the current level (e.g., 32 seconds) among predefined second levels (e.g., 4 seconds, 8 seconds, 16 seconds, 32 seconds, 64 seconds, 128 seconds, 256 seconds, and 512 seconds) based on the determination that the load exceeds a first value. That is, since the regulation of the UAC barring time increases as the value increases, the DU (420) can determine a UAC barring time that has a value greater than the current value.

[0210] In operation 1109, the DU (420) according to one embodiment may determine whether the load is less than or equal to a second value based on the determination that the load is less than or equal to a first value. For example, the second value may be the value obtained by subtracting an offset value (or alpha) from the previous load. In one example, operation 1109 may be expressed according to the following mathematical formula 5.

[0211]

[0212] In Equation 5, Current Load is the load identified based on load information. Prior Load is the load identified based on load information from the previous cycle. The offset value is a predefined offset value.

[0213] In operation 1110, the DU (420) according to one embodiment can determine UAC barring parameters having a regulation level preceding the current regulation level based on the determination that the load is less than or equal to a second value.

[0214] For example, the DU (420) can determine a UAC barring factor having a level (e.g., 0.60) that follows the current level (e.g., 0.50) among predefined first levels (e.g., 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.30, 0.40, 0.50, 0.60, 0.70, 0.75, 0.80, 0.85, 0.90, and 0.95) based on the determination that the load is less than or equal to a second value. That is, since the regulation of the UAC barring factor decreases as the value increases, the DU (420) can determine a UAC barring factor having a value greater than the current value. For example, the DU (420) can determine a UAC barring time for a level (e.g., 16 seconds) that precedes the current level (e.g., 32 seconds) among predefined second levels (e.g., 4 seconds, 8 seconds, 16 seconds, 32 seconds, 64 seconds, 128 seconds, 256 seconds, and 512 seconds) based on the determination that the load is less than or equal to a second value. That is, since the regulation of the UAC barring time decreases as the value decreases, the DU (420) can determine a UAC barring time that has a value smaller than the current value.

[0215] In operation 1111, the DU (420) according to one embodiment may maintain UAC barring parameters upon determining that the load exceeds a second value. For example, the DU (420) may maintain the previous UAC barring parameters when the load is between a first value and a second value.

[0216] In operation 1112, a DU (420) according to one embodiment may transmit a system information block (SIB) to a UE (120). For example, the SIB may be SIB1. For example, in a first overload state and a second overload state, SIB1 may include UAC barring parameters (e.g., UAC barring factor and UAC barring time). In another example, in a normal load state, SIB1 may not include UAC barring parameters.

[0217] FIG. 12 is a flowchart illustrating the operations of a DU under a second overload condition. The operations of FIG. 12 can be performed by a DU (distributed unit) (420). For example, at least some of the operations can be controlled by a processor (450) of the DU (420). In the following, each operation may be performed sequentially, but is not necessarily performed sequentially. For example, the order of each operation may be changed and / or at least two operations may be performed in parallel.

[0218] Referring to FIG. 12, in operation 1201, a DU (420) according to one embodiment can acquire load information while operating in a second overload state. For example, the load information may include CU (central unit) load information and / or LTE (long term evolution) load information.

[0219] In one embodiment, the DU (420) may receive (or obtain) CU load information from the CU (central unit) (410) while operating in a second overload state. For example, the CU (410) may periodically transmit (or provide) the CU load information to the DU (420). In another example, the CU (410) may transmit (or provide) the CU load information to the DU (420) when the CU load changes above a threshold value during a predefined time interval. In one example, the CU load information may be referred to as F1AP (F1 application protocol) gNB (gNodeB)-CU load information or other terms having an equivalent technical / functional meaning.

[0220] For example, CU load information may include a load list. For example, the load list may include load information of a first type and / or load information of a second type.

[0221] For example, the load information of the first type may represent the CPU (central processing unit) load of the CU (410). In one example, the CPU load may be the utilization of at least one CPU of the CU (410). However, this is merely an example and the present disclosure is not limited thereto. For example, the CPU load may be the sum of the number of processes running on at least one CPU of the CU (410) and the number of processes waiting on at least one CPU of the CU (410).

[0222] For example, the second type of load information may represent the radio resource control (RRC) load of the CU (410). In one example, the RRC load may be a ratio between the number of UEs connected to cells provided by the CU (410) and the maximum number of UEs that can be connected to the CU (410). However, this is merely an example and the present disclosure is not limited thereto. For example, the RRC load may be the number of RRC connection request messages per unit time received by the CU (410). In another example, the RRC load may be the number of RRC rejection messages per unit time transmitted by the CU (410).

[0223] In one embodiment, the DU (420) may receive (or obtain) LTE load information from the base station (710) while operating in a second overload state. For example, the base station (710) may periodically transmit (or provide) the LTE load information to the DU (420). In another example, the base station (710) may transmit (or provide) the LTE load information to the DU (420) when the LTE load included in the LTE load information changes by more than a threshold value during a predefined time interval. In one example, the LTE load information may be referred to as X2AP (X2 application protocol) LTE load information or other terms having an equivalent technical / functional meaning.

[0224] For example, LTE load information may include a load list. For example, the load list may include load information of a third type and / or load information of a fourth type.

[0225] For example, the load information of the third type may represent the CPU load of the base station (710). In one example, the CPU load may be the utilization of at least one CPU of the base station (710). However, this is merely an example and the present disclosure is not limited thereto. For example, the CPU load may be the sum of the number of processes running on at least one CPU of the base station (710) and the number of processes waiting on at least one CPU of the base station (710).

[0226] For example, the load information of the fourth type may be the RRC load of the base station (710). In one example, the RRC load may be the ratio between the number of UEs connected to cells provided by the base station (710) and the maximum number of UEs that can be connected to the base station (710). However, this is merely an example and the present disclosure is not limited thereto. For example, the RRC load may be the number of RRC connection request messages per unit time received by the base station (710). In another example, the RRC load may be the number of RRC rejection messages per unit time transmitted by the base station (710).

[0227] In operation 1202, the DU (420) according to one embodiment can identify a load based on load information. For example, the load identified based on load information may be the CPU load of the CU (410), the RRC load of the CU (410), the CPU load of the base station (710), or the DSS (dynamic spectrum sharing) RRC load. For example, the CPU load of the CU (410) may be identified based on a first type of load information. For example, the RRC load of the CU (410) may be identified based on a second type of load information. For example, the CPU load of the base station (710) may be identified based on a third type of load information. For example, the DSS RRC load may be identified based on a second type of load information and a fourth type of load information. For a description of the DSS RRC load, the above-described Equation 3 and the description of Equation 3 may be referenced.

[0228] In operation 1203, the DU (420) according to one embodiment may determine whether the load is below a second threshold value. For example, the second threshold value may be a value predefined for transitioning between a first overload state and a second overload state. In one example, the second threshold value may be referred to as threshold-high-overload or other terms having an equivalent technical / functional meaning.

[0229] In operation 1204, the DU (420) according to one embodiment may determine unified access control (UAC) barring parameters having a minimum regulation level based on the determination that the load is below a second threshold value. For example, the minimum regulation level may mean the level with the smallest regulation among the levels predefined for UAC.

[0230] For example, UAC barring parameters may include a UAC barring factor and / or a UAC barring time. The UAC barring factor may indicate the probability that an access attempt will be allowed during an access barring check. The UAC barring time may indicate the average time from when an access attempt is barred until a new access attempt is performed during an access barring check for the same access category.

[0231] For example, the DU (420) may change the UAC state from a second overload state to a first overload state upon determining that the load is below a second threshold value. In response to entering the first overload state, the DU (420) may determine a UAC barring factor having a minimum regulation level (e.g., 0.95) among predefined first levels (e.g., 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.30, 0.40, 0.50, 0.60, 0.70, 0.75, 0.80, 0.85, 0.90, and 0.95). That is, the DU (420) may determine a UAC barring factor having a maximum value among predefined values ​​for the UAC barring factor. For example, the DU (420) can determine a UAC barring time having a minimum regulation level (e.g., 4 seconds) among predefined second levels (e.g., 4 seconds, 8 seconds, 16 seconds, 32 seconds, 64 seconds, 128 seconds, 256 seconds, and 512 seconds) in response to entering a first overload state. That is, the DU (420) can determine a UAC barring factor having a minimum value among predefined values ​​for the UAC barring time.

[0232] In the example described above, the UE (120) can identify that the access attempt is permitted if the random number is less than or equal to the value indicated by the UAC barring factor (e.g., 0.95). Alternatively, the UE (120) can identify that the access attempt is barred if the random number exceeds the value indicated by the UAC barring factor (e.g., 0.95). Additionally, if the access attempt is barred, the UE (120) can wait for a timer determined based on the value indicated by the UAC barring time (e.g., 4 seconds).

[0233] In operation 1205, the DU (420) according to one embodiment may maintain UAC barring parameters upon determining that the load exceeds a second threshold value.

[0234] In operation 1206, a DU (420) according to one embodiment may transmit a system information block (SIB) to a UE (12). For example, the SIB may be SIB1. For example, SIB1 may include UAC barring parameters (e.g., UAC barring factor and UAC barring time).

[0235] Figure 13 illustrates an example of a combined UAC barring.

[0236] FIG. 13 illustrates UAC (unified access control) barring methods for determining UAC barring parameters. For example, UAC methods may be classified according to load type. For example, UAC methods may include a DU (distributed unit) CPU (central processing unit) load-based UAC (1301), a DU RRC (radio resource control) load-based UAC (1302), an AMF (access and mobility management function) overload-based UAC (1303), a CU overload-based UAC (1304), a CU (central unit) CPU load-based UAC (1305), a CU RRC load-based UAC (1306), a DSS (dynamic spectrum sharing) RRC load-based UAC (1307), and / or a DSS LTE (long term evolution) CPU load-based UAC (1308). For example, a user (or operator) can set the on / off status of UAC mechanisms.

[0237] In one embodiment, the DU CPU load-based UAC (1301) is a technique for determining UAC barring parameters based on the CPU load of the DU (420). For example, the DU (420) may determine first UAC barring parameters based on the CPU load of the DU (420). To determine the first UAC barring parameters, the methods described in FIGS. 10 through 12 may be applied substantially the same.

[0238] In one embodiment, the DU RRC load-based UAC (1302) is a technique for determining UAC barring parameters based on the RRC load of the DU (420). For example, the DU (420) may determine second UAC barring parameters based on the RRC load of the DU (420). To determine the second UAC barring parameters, the methods described in FIGS. 10 through 12 may be applied substantially the same way.

[0239] In one embodiment, the AMF overload-based UAC (1303) is a technique for reducing the network access rate based on the overload of the AMF (520) described in FIGS. 5a to 5c. For example, the DU (420) can determine third UAC barring parameters based on the contents described in FIGS. 5a to 5c.

[0240] In one embodiment, the CU overload-based UAC (1304) is a technique for reducing the network connection rate based on the overload of the CU (410) described in FIG. 6a. For example, the DU (420) can determine the fourth UAC barring parameters based on the contents described in FIG. 6a.

[0241] In one embodiment, the CU CPU load-based UAC (1305) is a technique for determining UAC barring parameters based on the CPU load of the CU (410). For example, the DU (420) may determine the fifth UAC barring parameters based on first type load information indicating the CPU load of the CU (410). To determine the fifth UAC barring parameters, the descriptions of FIGS. 10 through 12 may be referenced.

[0242] In one embodiment, the CU RRC load-based UAC (1306) is a technique for determining UAC barring parameters based on the RRC load of the CU (410). For example, the DU (420) may determine the sixth UAC barring parameters based on second type load information indicating the RRC load of the CU (410). To determine the sixth UAC barring parameters, the descriptions of FIGS. 10 through 12 may be referenced.

[0243] In one embodiment, the DSS RRC load-based UAC (1307) is a technique for determining UAC barring parameters based on the RRC load of the CU (410) and the RRC load of the base station (710). For example, the DU (420) may determine the seventh UAC barring parameters based on second type load information indicating the RRC load of the CU (410) and fourth type load information indicating the RRC load of the base station (710). To determine the seventh UAC barring parameters, the descriptions of FIGS. 10 through 12 may be referenced.

[0244] In one embodiment, the DSS LTE CPU load-based UAC (1308) is a technique for determining UAC barring parameters based on the CPU load of the base station (710). For example, the DU (420) may determine eighth UAC barring parameters based on third-type load information indicating the CPU load of the base station (710). To determine the eighth UAC barring parameters, the descriptions of FIGS. 10 through 12 may be referenced.

[0245] In one embodiment, combined UAC barring (1309) is a technique for identifying the UAC barring parameters that are most restricted among the UAC barring parameters obtained by UAC techniques that are turned on by a user (or, operator). In one example, CU CPU load-based UAC (1305), CU RRC load-based UAC (1306), DSS RRC load-based UAC (1307), and DSS LTE CPU load-based UAC (1308) may be turned on by a user (or, operator), and DU CPU load-based UAC (1301), DU RRC load-based UAC (1302), AMF overload-based UAC (1303), and CU overload-based AUC (1304) may be turned off. In the example described above, the UAC barring factors obtained based on each load type and the UAC barring factors identified based on the combined UAC barring (1309) may be as shown in Table 8 below.

[0246] T2T3T4T5T6T7T5th Technique p70p70p80----6th Technique p60p60p70p70p60p70-7th Technique p80p75p70p60p50p40p008th Technique---p70p70p70p60Combined UAC Barring p60p60p70p60p50p40p00

[0247] In the example described above, the UAC barring times obtained based on each load type and the UAC barring times identified based on the combined UAC barring (1309) may be as shown in Table 9 below.

[0248] T2T3T4T5T6T7T5th technique s8s8s4----6th technique s16s16s4s8s4s8-7th technique s4s4s8s16s32s64s5128th technique---s4s4s4s8 combined UAC barring s16s16s8s16s32s64s512

[0249] In Tables 8 and 9, the fifth technique is a CU CPU load-based UAC (1305). The sixth technique is a CU RRC load-based UAC (1306). The seventh technique is a DSS RRC load-based UAC (1307). The eighth technique is a DSS LTE CPU load-based UAC.

[0250] Referring to Table 8, in the first period (T), the UAC barring factor obtained by the fifth technique is 70%, the UAC barring factor obtained by the sixth technique is 60%, the UAC barring factor obtained by the seventh technique is 80%, and UAC barring may not be performed in the eighth technique. Therefore, according to the combined UAC barring (1309), the DU (420) can determine the UAC barring factor having the largest regulation of 60% among the UAC barring factors.

[0251] Referring to Table 9, in the first period (T), the UAC barring time obtained by the fifth technique is 8 seconds, the UAC barring time obtained by the sixth technique is 16 seconds, the UAC barring time obtained by the seventh technique is 4 seconds, and UAC barring may not be performed in the eighth technique. Therefore, according to the combined UAC (1309), the DU (420) can determine the UAC barring time having the largest regulation of 16 seconds among the UAC barring times.

[0252] The DU (420) can transmit a system information block (SIB) 1, which includes a UAC barring factor indicating 60% and a UAC barring time indicating 16 seconds, to the UE (user equipment) (120). The DU (420) can transmit a SIB 1, which includes a UAC barring factor and a UAC barring time determined according to the method described above, to the UE (120) during the second cycle (2T) through the seventh cycle (7T).

[0253] FIGS. 14a and FIGS. 14b illustrate charts showing the load according to overload control.

[0254] In FIG. 14a, the horizontal axis of the chart (1410) represents time. On the vertical axis of the chart (1410), the waveform (1401) represents the CPU (central processing) load of the central unit (CU). On the vertical axis of the chart (1410), the grade (1451) represents normal among the overload grades of the CU (410). On the vertical axis of the chart (1410), the grade (1452) represents minor among the overload grades of the CU (410). On the vertical axis of the chart (1410), the grade (1453) represents major among the overload grades of the CU (410). On the vertical axis of the chart (1410), the grade (1454) represents critical among the overload grades of the CU (410). CU (410) can perform call admission control (CAC) based on the determination that the overload level is critical. For example, CU (410) can reject new calls by performing CAC.

[0255] Referring to FIG. 14a, a DU (distributed unit) (420) operating in a normal load state can receive (or obtain) CU load information from a CU (410). The CU load information may represent the CPU load of the CU (410) during a guard time (1402).

[0256] For example, the DU (420) can determine whether the CPU load of the CU (410) exceeds a first threshold (1411) during the guard time (1402). In one example, since the CPU load of the CU (410) changes non-linearly, the DU (420) can determine whether the CPU load continuously exceeds the first threshold (1411) during the guard time (1402). However, this is merely an example and the present disclosure is not limited thereto. For example, the DU (420) can determine whether the CPU load exceeds the first threshold (1411) during at least part of the guard time (1402).

[0257] For example, the DU (420) may trigger an event to enter from a normal load state to a first overload state at time (1421) upon determining that the CPU load of the CU (410) exceeds a first threshold value (1411) during the guard time (1402). The DU (420) may enter the first overload state in response to triggering the event. The DU (420) may apply unified access control (UAC) barring parameters having the least restrictive level to system information block (SIB) 1 at time (1431) after the event is triggered. In one example, the DU (420) may apply a UAC barring factor to SIB1 having a minimum regulatory level (e.g., 0.95) among predefined first levels (e.g., 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.30, 0.40, 0.50, 0.60, 0.70, 0.75, 0.80, 0.85, 0.90, and 0.95). In one example, the DU (420) may apply a UAC barring time to SIB1 having a minimum regulatory level (e.g., 4 seconds) among predefined second levels (e.g., 4 seconds, 8 seconds, 16 seconds, 32 seconds, 64 seconds, 128 seconds, 256 seconds, and 512 seconds).

[0258] For example, between time (1431) and time (1432), the DU (420) can operate in a first overload state. The DU (420) can determine UAC barring parameters according to the method described in FIG. 11.

[0259] Referring to FIG. 14a, the DU (420) operating in the first overload state can receive (or obtain) CU load information from the CU (410). For example, the CU load information may indicate the CPU load of the CU (410) during the guard time (1403).

[0260] For example, the DU (420) can determine whether the CPU load of the CU (410) exceeds the second threshold (1412) during the guard time (1403). In one example, the DU (420) can determine whether the CPU load continuously exceeds the second threshold (1412) during the guard time (1403). However, this is merely an example and the present disclosure is not limited thereto. For example, the DU (420) can determine whether the CPU load exceeds the second threshold (1412) during at least part of the guard time (1403).

[0261] For example, the DU (420) may trigger an event to enter from a first overload state to a second overload state at time (1422) upon determining that the CPU load of the CU (410) exceeds a second threshold value (1412) during the guard time (1403). The DU (420) may enter the second overload state in response to triggering the event. The DU (420) may apply UAC barring parameters having the most restrictive level to SIB1 at time (1432) after the event is triggered. In one example, the DU (420) may apply a UAC barring factor to SIB1 having a maximum regulated level (e.g., 0) among predefined first levels (e.g., 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.30, 0.40, 0.50, 0.60, 0.70, 0.75, 0.80, 0.85, 0.90, and 0.95). In one example, the DU (420) may apply a UAC barring time to SIB1 having a maximum regulated level (e.g., 512 seconds) among predefined second levels (e.g., 4 seconds, 8 seconds, 16 seconds, 32 seconds, 64 seconds, 128 seconds, 256 seconds, and 512 seconds).

[0262] As described above, the DU (420) can proactively perform overload control based on CU load information obtained from the CU (410). By proactively performing overload control, the DU (420) can prevent the CU (410) from entering a critical level (1454). Since the CU (410) does not enter a critical level (1454), call rejection due to CAC (call admission control) may not occur.

[0263] FIG. 14b illustrates a chart showing the load according to overload control.

[0264] In FIG. 14b, the horizontal axis of the chart (1410) represents time. On the vertical axis of the chart (1410), waveform (1461) represents the radio resource control (RRC) load of the central unit (CU) (410). On the vertical axis of the chart (1410), waveform (1462) represents the RRC load of an LTE base station (e.g., base station (710)). On the vertical axis of the chart (1410), waveform (1463) represents the dynamic spectrum sharing (DSS) RRC load. On the vertical axis of the chart (1410), grade (1451) represents normal among the overload grades of the CU (410). On the vertical axis of the chart (1410), grade (1452) represents minor among the overload grades of the CU (410). On the vertical axis of the chart (1410), the grade (1453) represents the major among the overload grades of the CU (410). On the vertical axis of the chart (1410), the grade (1454) represents the critical among the overload grades of the CU (410).

[0265] Referring to FIG. 14b, a distributed unit (DU) (420) operating in a normal load state may receive (or obtain) CU load information from a CU (410) and receive (or obtain) LTE load information from an LTE base station. The CU load information may represent the RRC load of the CU (410) during guard time (1464). The LTE load information may represent the RRC load of the LTE base station during guard time (1464). For example, the DU (420) may determine the DSS RRC load during guard time (1464) based on the RRC load of the CU (410) and the RRC load of the LTE base station. For the method of determining the DSS RRC load, the above-described Equation 3 and the description of Equation 3 may be referenced.

[0266] For example, the DU (420) can determine whether the DSS RRC load exceeds the first threshold (1411) during the guard time (1464). In one example, since the DSS RRC load changes non-linearly, the DU (420) can determine whether the DSS RRC load continuously exceeds the first threshold (1411) during the guard time (1464). However, this is merely an example and the present disclosure is not limited thereto. For example, the DU (420) can determine whether the DSS RRC load exceeds the first threshold (1411) during at least part of the guard time (1464).

[0267] For example, the DU (420) may trigger an event to enter a first overload state from a normal load state at time (1471) upon determining that the DSS RRC load exceeds a first threshold value (1411) during the guard time (1464). The DU (420) may enter the first overload state in response to triggering the event. The DU (420) may apply unified access control (UAC) barring parameters having the least restrictive level to system information block (SIB) 1 at time (1481) after the event is triggered. In one example, the DU (420) may apply a UAC barring factor to SIB1 having a minimum regulatory level (e.g., 0.95) among predefined first levels (e.g., 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.30, 0.40, 0.50, 0.60, 0.70, 0.75, 0.80, 0.85, 0.90, and 0.95). In one example, the DU (420) may apply a UAC barring time to SIB1 having a minimum regulatory level (e.g., 4 seconds) among predefined second levels (e.g., 4 seconds, 8 seconds, 16 seconds, 32 seconds, 64 seconds, 128 seconds, 256 seconds, and 512 seconds).

[0268] For example, between time (1481) and time (1482), the DU (420) can operate in a first overload state. The DU (420) can determine UAC barring parameters according to the method described in FIG. 11.

[0269] Referring to FIG. 14b, the DU (420) operating in the first overload state may receive (or obtain) CU load information from the CU (410) and receive (or obtain) LTE load information from the LTE base station. The CU load information may represent the RRC load of the CU (410) during guard time (1465). The LTE load information may represent the RRC load of the LTE base station during guard time (1465). For example, the DU (420) may determine the DSS RRC load during guard time (1465) based on the RRC load of the CU (410) and the RRC load of the LTE base station.

[0270] For example, the DU (420) can determine whether the DSS RRC load exceeds a second threshold (1412) during the guard time (1465). In one example, the DU (420) can determine whether the DSS RRC load continuously exceeds the second threshold (1412) during the guard time (1465). However, this is merely an example and the present disclosure is not limited thereto. For example, the DU (420) can determine whether the DSS RRC load exceeds a first threshold (1411) during at least part of the guard time (1465).

[0271] For example, the DU (420) may trigger an event to enter from a first overload state to a second overload state at time (1472) upon determining that the DSS RRC load exceeds a second threshold value (1412) during the guard time (1465). The DU (420) may enter the second overload state in response to triggering the event. The DU (420) may apply UAC barring parameters having the most restrictive level to SIB1 at time (1482) after the event is triggered. In one example, the DU (420) may apply a UAC barring factor to SIB1 having a maximum regulated level (e.g., 0) among predefined first levels (e.g., 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.30, 0.40, 0.50, 0.60, 0.70, 0.75, 0.80, 0.85, 0.90, and 0.95). In one example, the DU (420) may apply a UAC barring time to SIB1 having a maximum regulated level (e.g., 512 seconds) among predefined second levels (e.g., 4 seconds, 8 seconds, 16 seconds, 32 seconds, 64 seconds, 128 seconds, 256 seconds, and 512 seconds).

[0272] As described above, the DU (420) can proactively perform overload control based on CU load information obtained from the CU (410) and LTE load information obtained from the LTE base station. By proactively performing overload control, the DU (420) can prevent the CU (410) from entering a critical level (1454). Since the CU (410) does not enter a critical level (1454), call rejection due to CAC (call admission control) may not occur.

[0273] Figure 15 illustrates examples of signaling for barring in NR and LTE.

[0274] Some of the operations of FIG. 15 (e.g., operations 1551, 1552, 1553, and 1554) are described based on a DU (distributed unit) (420). The remaining operations of FIG. 15 (e.g., operations 1561, 1562, 1563, and 1564) are described based on a base station (710). In the following, each operation may be performed sequentially, but is not necessarily performed sequentially. For example, the order of each operation may be changed and / or at least two operations may be performed in parallel.

[0275] FIG. 15 illustrates a central unit (CU) (410), a DU (420), and a base station (710) for providing dynamic spectrum sharing (DSS). The base station (710) may be an eNB (eNodeB) that supports LTE. However, the present disclosure is not limited thereto. In the following, the CU (410) and the DU (420) may be replaced with entities that support a first radio access technology (RAT), and the base station (710) may be replaced with entities that support a second RAT that is different from the first RAT.

[0276] A barring technique in NR (new radio) is described. Referring to FIG. 15, in operation 1551, a DU (420) according to one embodiment may receive (or obtain) CU (central unit) load information from a CU (410). In one example, the CU load information may be referred to as F1AP (F1 application protocol) gNB (gNodeB)-CU load information or other terms having an equivalent technical / functional meaning. For example, the CU load information may include a first type of load information and / or a second type of load information.

[0277] For example, the load information of the first type may be the CPU (central processing unit) load of the CU (410). In one example, the CPU load may be the utilization of at least one CPU of the CU (410). However, this is merely an example and the present disclosure is not limited thereto. For example, the CPU load may be the sum of the number of processes running on at least one CPU of the CU (410) and the number of processes waiting on at least one CPU of the CU (410).

[0278] For example, the second type of load information may be the radio resource control (RRC) load of the CU (410). In one example, the RRC load may be a ratio between the number of UEs connected to cells provided by the CU (410) and the maximum number of UEs that can be connected to the CU (410). However, this is merely an example and the present disclosure is not limited thereto. For example, the RRC load may be the number of RRC connection request messages per unit time received by the CU (410). In another example, the RRC load may be the number of RRC rejection messages per unit time transmitted by the CU (410).

[0279] In operation 1552, a DU (420) according to one embodiment may receive (or obtain) LTE load information from a base station (710). In one example, the LTE load information may be referred to as X2AP (X2 application protocol) LTE load information or other terms having an equivalent technical / functional meaning. For example, the LTE load information may include load information of a third type and / or load information of a fourth type.

[0280] For example, the load information of the third type may be the CPU load of the base station (710). In one example, the CPU load may be the utilization of at least one CPU of the base station (710). However, this is merely an example and the present disclosure is not limited thereto. For example, the CPU load may be the sum of the number of processes running on at least one CPU of the base station (710) and the number of processes waiting on at least one CPU of the base station (710).

[0281] For example, the load information of the fourth type may be the RRC load of the base station (710). In one example, the RRC load may be the ratio between the number of UEs connected to cells provided by the base station (710) and the maximum number of UEs that can be connected to the base station (710). However, this is merely an example and the present disclosure is not limited thereto. For example, the RRC load may be the number of RRC connection request messages per unit time received by the base station (710). In another example, the RRC load may be the number of RRC rejection messages per unit time transmitted by the base station (710).

[0282] In operation 1553, the DU (420) according to one embodiment can determine UAC barring parameters.

[0283] In one embodiment, the DU (420) can determine first UAC barring parameters related to the CPU load of the CU (410) based on first type load information. For a method of determining the first UAC barring parameters, the contents of FIGS. 10 to 12 may be referenced.

[0284] In one embodiment, the DU (420) can determine second UAC barring parameters related to the RRC load of the CU (410) based on second type load information. For a method of determining the second UAC barring parameters, the contents of FIGS. 10 to 12 may be referenced.

[0285] In one embodiment, the DU (420) can determine third UAC barring parameters related to the CPU load of the base station (710) based on third type load information. For a method of determining the third UAC barring parameters, the contents of FIGS. 10 to 12 may be referenced.

[0286] In one embodiment, the DU (420) can determine fourth UAC barring parameters related to the dynamic spectrum sharing (DSS) RRC load based on second type load information and fourth type load information. Reference may be made to the contents of FIGS. 10 to 12 for the method of determining the fourth UAC barring parameters.

[0287] For example, DU (420) may determine the first to fourth UAC barring parameters. However, this is merely an example and the present disclosure is not limited thereto. For example, DU (420) may determine only some of the first to fourth UAC barring parameters according to the settings of the user (or operator).

[0288] In one embodiment, DU (420) can identify the UAC barring parameters that are most regulated among the first to fourth UAC barring parameters. For a method of identifying UAC barring parameters, the contents of FIG. 13 may be referenced.

[0289] In operation 1554, a DU (420) according to one embodiment may transmit a SIB1 (system information block) containing UAC barring parameters to a UE (user equpment) (1501).

[0290] A barring technique in LTE (long term evolution) is described. Referring to FIG. 15, a base station (710) may receive (or acquire) NR load information from a DU (420). In one example, NR load information may be referred to as X2AP gNB-load information or other terms having an equivalent technical / functional meaning. For example, NR load information may include load information of type 5 and / or load information of type 6.

[0291] For example, the load information of the fifth type may be the CPU load of the DU (420). In one example, the CPU load may be the utilization rate of at least one CPU of the DU (420). However, this is merely an example and the present disclosure is not limited thereto. For example, the CPU load may be the sum of the number of processes running on at least one CPU of the DU (420) and the number of processes waiting on at least one CPU of the DU (420).

[0292] For example, the load information of the sixth type may be the RRC load of the DU (420). In one example, the RRC load may be the ratio between the number of UEs connected to the cells provided by the DU (420) and the maximum number of UEs that can be connected to the DU (420). However, this is merely an example and the present disclosure is not limited thereto. For example, the RRC load may be the number of RRC connection request messages per unit time received by the DU (420). In another example, the RRC load may be the number of RRC rejection messages per unit time transmitted by the DU (420).

[0293] In operation 1562, a base station (710) according to one embodiment can determine AC (access control) barring parameters.

[0294] In one embodiment, the base station (710) can determine first AC barring parameters related to the CPU load of the DU (420) based on fifth type load information. For a method of determining the first AC barring parameters, the contents of FIGS. 10 to 12 may be referenced.

[0295] In one embodiment, the base station (710) can determine second AC barring parameters related to the DSS RRC load based on fifth type load information and sixth type load information. For a method of determining the second AC barring parameters, the contents of FIGS. 10 to 12 may be referenced.

[0296] For example, the base station (710) may determine the first AC baring parameters and the second AC baring parameters. However, this is merely an example and the present disclosure is not limited thereto. For example, the base station (710) may determine only some of the first AC baring parameters and the second AC baring parameters according to the settings of the user (or operator).

[0297] In one embodiment, the base station (710) can identify the AC barring parameters that are most restricted among the first AC barring parameters and the second AC barring parameters. For a method of identifying AC barring parameters, the contents of FIG. 13 may be referenced.

[0298] In operation 1563, a base station (710) according to one embodiment may transmit a system information block (SIB) 1 to a UE (1502). For example, the base station (110) may transmit the SIB 1 to the UE (1502) by broadcasting the SIB 1. For example, the SIB 1 may include information for evaluating whether the UE (1502) can access a cell and / or scheduling information of other system information (OSI).

[0299] In one embodiment, the OSI scheduling information may include a list of SIBs mapped to SIB1, the periodicity of the SIBs, and / or a scheduling window length for the SIBs. For example, the list may include SIBs associated with the OSI scheduling information included in SIB1. In one example, the list may always include SIB2. For example, the period may represent the transmission period of the SIBs. In one example, the period may be one of 8RF (radio frame), 16RF, 32RF, 64RF, 128RF, 256RF, or 512RF. For example, the scheduling window length may represent the time length for monitoring (or receiving) the SIBs. In one example, the scheduling window length may be one of 1ms (millisecond), 2ms, 5ms, 15ms, 20ms, or 40ms.

[0300] In operation 1564, a base station (710) according to one embodiment may transmit SIB2 to a UE (1502). For example, the base station (710) may transmit SIB2 to the UE (1502) by broadcasting SIB2. For example, the UE (1502) may receive SIB2 based on scheduling information contained in SIB1. For example, SIB2 may include AC barring parameters determined in operation 1562.

[0301] The technical problems to be solved in this disclosure are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this disclosure pertains.

[0302] A distributed unit (DU) as described above may include a communication circuit. The DU may include a memory that stores instructions and includes one or more storage media. The DU may include at least one processor that includes a processing circuit. When the instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to obtain CU load information from the CU that indicates the load of the CU connected to the DU via an F1 interface. When the instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine a unified access control (UAC) barring factor and a UAC barring time based on the load of the CU indicated by the CU load information. When the above instructions are executed individually or collectively by the at least one processor, the DU may cause the system information block (SIB) including the UAC barring factor and the UAC barring time to be transmitted to the user equipment (UE).

[0303] For example, when the above instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine whether the load of the CU, indicated by the CU load information, exceeds a first threshold value when the DU is operating in a normal load state. When the above instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine the UAC barring factor having the maximum level among predefined first levels and the UAC barring time having the minimum level among predefined second levels, depending on the determination that the load of the CU exceeds the first threshold value, and change the UAC state of the DU from the normal load state to a first overload state.

[0304] For example, when the instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine whether the load of the CU, indicated by the CU load information, exceeds a second threshold greater than the first threshold while the DU is operating in a first overload state. When the instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine the UAC barring factor having a minimum level among predefined first levels and the UAC barring time having a maximum level among predefined second levels, and change the UAC state of the DU from the first overload state to the second overload state, depending on the determination that the load of the CU exceeds the second threshold.

[0305] For example, when the instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine whether the load of the CU exceeds a first value determined from the prior load of the CU, based on the determination that the load of the CU is less than or equal to the second threshold value. When the instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine the UAC barring factor having a level subsequent to the current level among the predefined first levels and the UAC barring time having a level subsequent to the current level among the predefined second levels, based on the determination that the load exceeds the first value. The first value may be determined by adding an offset value to the prior load.

[0306] For example, when the above instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine whether the load of the CU is less than or equal to a second value determined from the previous load of the CU, based on the determination that the load of the CU is less than or equal to the second threshold value. When the above instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine the UAC barring factor having a level prior to the current level among the predefined first levels and the UAC barring time having a level prior to the current level among the predefined second levels, based on the determination that the load is less than or equal to the second value. The second value may be determined by subtracting the offset value from the previous load.

[0307] For example, the CU load information may include first type load information and second type load information. The first type load information may represent the CPU (central processing unit) load of the CU. The second type load information may represent the number of UEs connected to the CU.

[0308] For example, when the above instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to obtain LTE load information from the LTE base station indicating the load of the LTE (long term evolution) base station that supports DSS (dynamic spectrum sharing) together with the DU. The LTE load information may include a third type of load information and a fourth type of load information. The third type of load information may indicate the CPU load of the LTE base station. The fourth type of load information may indicate the number of UEs connected to the LTE base station.

[0309] For example, when the above instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine a first UAC barring factor and a first UAC barring time based on the first type of load information. When the above instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine a second UAC barring factor and a second UAC barring time based on the second type of load information. When the above instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine a third UAC barring factor and a third UAC barring time based on the third type of load information. When the above instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine a fourth UAC barring factor and a fourth UAC barring time based on the second type of load information and the fourth type of load information.

[0310] For example, when the instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine the UAC barring factor having the maximum level among the first UAC barring factor, the second UAC barring factor, the third UAC barring factor, and the fourth UAC barring factor. When the instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to determine the UAC barring time having the maximum level among the first UAC barring time, the second UAC barring time, the third UAC barring time, and the fourth UAC barring time.

[0311] For example, when the above instructions are executed individually or collectively by the at least one processor, the DU may cause the DU to refrain from determining the UAC barring factor and the UAC barring time based on the determination that the load of the CU indicated by the CU load information is below a first threshold value.

[0312] A method performed by a DU (distributed unit) as described above may include an operation of obtaining CU load information from the CU that indicates the load of the CU (central unit) connected to the DU through an F1 interface. The method may include an operation of determining a UAC (unified access control) barring factor and a UAC barring time based on the load of the CU indicated by the CU load information. The method may include an operation of transmitting a SIB (system information block) including the UAC barring factor and the UAC barring time to a UE (user equipment).

[0313] For example, the above method may include an operation to determine whether the load of the CU, indicated by the CU load information, exceeds a first threshold value when the DU is operating in a normal load state. The above method may include, upon the determination that the load of the CU exceeds the first threshold value, an operation to determine the UAC barring factor having a maximum level among predefined first levels and the UAC barring time having a minimum level among predefined second levels, and an operation to change the UAC state of the DU from the normal load state to a first overload state.

[0314] For example, the above method may include an operation to determine whether the load of the CU, indicated by the CU load information, exceeds a second threshold value greater than the first threshold value while the DU is operating in a first overload state. The above method may include, upon the determination that the load of the CU exceeds the second threshold value, an operation to determine the UAC barring factor having a minimum level among predefined first levels and the UAC barring time having a maximum level among predefined second levels, and an operation to change the UAC state of the DU from the first overload state to the second overload state.

[0315] For example, the method may include an operation to determine whether the load of the CU exceeds a first value determined from the prior load of the CU, based on a determination that the load of the CU is less than or equal to the second threshold value. The method may include an operation to determine the UAC barring factor having a level subsequent to the current level among the predefined first levels and the UAC barring time having a level subsequent to the current level among the predefined second levels, based on a determination that the load exceeds the first value. The first value may be determined by adding an offset value to the prior load.

[0316] For example, the above method may include an operation of determining whether the load of the CU is less than or equal to a second value determined from the previous load of the CU, based on the determination that the load of the CU is less than or equal to the second threshold value. The above method may include an operation of determining the UAC barring factor having a level prior to the current level among the predefined first levels and the UAC barring time having a level prior to the current level among the predefined second levels, based on the determination that the load is less than or equal to the second value. The second value may be determined by subtracting the offset value from the previous load.

[0317] For example, the CU load information may include first type load information and second type load information. The first type load information may represent the CPU (central processing unit) load of the CU. The second type load information may represent the number of UEs connected to the CU.

[0318] For example, the above method may include the operation of obtaining LTE load information from the LTE base station that indicates the load of the LTE (long term evolution) base station supporting DSS (dynamic spectrum sharing) together with the DU. The LTE load information may include a third type of load information and a fourth type of load information. The third type of load information may indicate the CPU load of the LTE base station. The fourth type of load information may indicate the number of UEs connected to the LTE base station.

[0319] For example, the above method may include an operation of determining a first UAC barring factor and a first UAC barring time based on the first type of load information. The above method may include an operation of determining a second UAC barring factor and a second UAC barring time based on the second type of load information. The above method may include an operation of determining a third UAC barring factor and a third UAC barring time based on the third type of load information. The above method may include an operation of determining a fourth UAC barring factor and a fourth UAC barring time based on the second type of load information and the fourth type of load information.

[0320] For example, the above method may include an operation of determining the UAC barring factor having the maximum level among the first UAC barring factor, the second UAC barring factor, the third UAC barring factor, and the fourth UAC barring factor. The above method may include an operation of determining the UAC barring time having the maximum level among the first UAC barring time, the second UAC barring time, the third UAC barring time, and the fourth UAC barring time.

[0321] For example, it may include an operation to refrain from determining the UAC barring factor and the UAC barring time based on the determination that the load of the CU indicated by the CU load information is below a first threshold value.

[0322] The effects obtainable from the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present disclosure belongs.

[0323] For one or more embodiments, at least one of the components described in one or more of the prior art drawings may be configured to perform one or more operations, techniques, processes and / or methods as described in the present disclosure. For example, a processor (e.g., a baseband processor) described in the present disclosure in relation to one or more of the prior art drawings may be configured to operate according to one or more examples described in the present disclosure. As another example, circuits associated with user equipment (UE), a base station, a network element, etc., as described above in relation to one or more of the prior art drawings may be configured to operate according to one or more examples described herein.

[0324] Any of the embodiments described above may be combined with any other embodiment (or combination of embodiments) unless otherwise explicitly stated. The foregoing description of one or more embodiments is for illustrative and explanatory purposes only, and is not intended to limit or exhaust the scope of the embodiments in the exact form disclosed. Modifications and variations are possible in light of the foregoing teachings or may be obtained from the practice of various embodiments.

[0325] Methods according to the claims or embodiments described in the specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0326] When implemented in software, a computer-readable storage medium (e.g., a non-transient computer-readable storage medium) storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. One or more programs include instructions that cause the electronic device to execute methods according to the claims or embodiments described in the specification of this disclosure. The one or more programs may be provided as a computer program product. The computer program product may be traded between a seller and a buyer as a product. The computer program product may be distributed in the form of a device-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or distributed online (e.g., download or upload) through an application store (e.g., Play Store™) or directly between two user devices (e.g., smartphones). In the case of online distribution, at least a portion of the computer program product may be temporarily stored or temporarily created on a device-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or a relay server.

[0327] Such programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), magnetic disc storage devices, compact disc-ROM (CD-ROM), digital versatile discs (DVDs), or other forms of optical storage devices, magnetic cassettes. Alternatively, they may be stored in memory composed of some or all of these. Additionally, each constituent memory may include multiple units.

[0328] Additionally, the program may be stored on an attachable storage device that can be accessed via a communication network such as the Internet, Intranet, LAN (local area network), WAN (wide area network), or SAN (storage area network), or a combination thereof. Such a storage device may be connected to a device performing an embodiment of the present disclosure through an external port. Additionally, a separate storage device on a communication network may be connected to a device performing an embodiment of the present disclosure.

[0329] In the specific embodiments of the present disclosure described above, the components included in the disclosure are expressed in a singular or plural form according to the specific embodiments presented. However, the singular or plural expression is selected to suit the situation presented for convenience of explanation, and the present disclosure is not limited to singular or plural components; even if a component is expressed in the plural form, it may be composed of a singular form, and even if a component is expressed in the singular form, it may be composed of a plural form.

[0330] According to the embodiments, one or more of the aforementioned components or operations may be omitted, or one or more other components or operations may be added. Generally or additionally, a plurality of components (e.g., a module or a program) may be integrated into a single component. In this case, the integrated component may perform one or more functions of each of the plurality of components in the same or similar manner as those performed by the corresponding component among the plurality of components prior to the integration. According to the embodiments, operations performed by a module, program, or other component may be executed sequentially, in parallel, iteratively, or heuristically, or one or more of the operations may be executed in a different order, omitted, or one or more other operations may be added.

[0331] Meanwhile, although specific embodiments have been described in the detailed description of the present disclosure, it is understood that various modifications are possible within the scope of the present disclosure.

Claims

1. In the case of a DU (distributed unit), Communication circuit; Memory for storing instructions and including one or more storage media; and The DU comprises at least one processor including a processing circuit, wherein when the instructions are executed individually or collectively by the at least one processor, the DU Obtain CU load information from the CU that indicates the load of the CU (central unit) connected through the DU and F1 interface, and Based on the load of the CU indicated by the above CU load information, the UAC (unified access control) barring factor and UAC barring time are determined, and Causing to transmit a system information block (SIB) including the above UAC barring factor and the above UAC barring time to the user equipment (UE), DU.

2. In Paragraph 1, When the above instructions are executed individually or collectively by the at least one processor, the DU, When the above DU is operating in a normal load state, it is determined whether the load of the CU indicated by the CU load information exceeds a first threshold value, and Based on the determination that the load of the above CU exceeds the above first threshold value: Determining the UAC barring factor having the maximum level among predefined first levels and the UAC barring time having the minimum level among predefined second levels, and Causing the UAC state of the above DU to change from the normal load state to the first overload state, DU.

3. In Paragraph 1, When the above instructions are executed individually or collectively by the at least one processor, the DU, While the above DU is operating in a first overload state, it is determined whether the load of the CU indicated by the CU load information exceeds a second threshold value greater than the first threshold value, and Based on the determination that the load of the above CU exceeds the above second threshold value: Determining the UAC barring factor having a minimum level among predefined first levels and the UAC barring time having a maximum level among predefined second levels, and Causing the UAC state of the above DU to change from the first overload state to the second overload state, DU.

4. In Paragraph 3, When the above instructions are executed individually or collectively by the at least one processor, the DU, Based on the determination that the load of the CU is less than or equal to the second threshold value, it is determined whether the load of the CU exceeds a first value determined from the prior load of the CU, and, Based on the determination that the above load exceeds the above first value, cause to determine the UAC barring factor having a level subsequent to the current level among the above predefined first levels and the UAC barring time having a level subsequent to the current level among the above predefined second levels, and The above first value is determined by adding an offset value to the above previous load, DU.

5. In Paragraph 3, When the above instructions are executed individually or collectively by the at least one processor, the DU, Based on the determination that the load of the above CU is less than or equal to the second threshold value, it is determined whether the load of the above CU is less than or equal to the second value determined from the previous load of the above CU, and, Causing to determine the UAC barring factor having a level prior to the current level among the predefined first levels and the UAC barring time having a level prior to the current level among the predefined second levels, in accordance with the determination that the above load is less than or equal to the above second value, The above second value is determined by subtracting the offset value from the above previous load, DU.

6. In Paragraph 1, The above CU load information includes first type load information and second type load information, and The above-mentioned first type load information indicates the CPU (central processing unit) load of the above-mentioned CU, and The above second type load information indicates the number of UEs connected to the CU, DU.

7. In Paragraph 6, When the above instructions are executed individually or collectively by the at least one processor, the DU, Causing to obtain LTE load information from the LTE base station indicating the load of the LTE (long term evolution) base station that supports DSS (dynamic spectrum sharing) together with the above DU, and The above LTE load information includes load information of a third type and load information of a fourth type, and The above third type load information indicates the CPU load of the LTE base station, and The above-mentioned fourth type load information indicates the number of UEs connected to the LTE base station, DU.

8. In Paragraph 7, When the above instructions are executed individually or collectively by the at least one processor, the DU, Based on the load information of the first type above, a first UAC barring factor and a first UAC barring time are determined, and Based on the load information of the second type above, the second UAC barring factor and the second UAC barring time are determined, and Based on the load information of the third type above, the third UAC barring factor and the third UAC barring time are determined, and Causing to determine the fourth UAC barring factor and the fourth UAC barring time based on the above-mentioned second type load information and fourth type load information, DU.

9. In Paragraph 8, When the above instructions are executed individually or collectively by the at least one processor, the DU, Determining the UAC barring factor having the maximum level among the first UAC barring factor, the second UAC barring factor, the third UAC barring factor, and the fourth UAC barring factor, and Causing to determine the UAC barring time having the maximum level among the first UAC barring time, the second UAC barring time, the third UAC barring time, and the fourth UAC barring time, DU.

10. In Paragraph 1, When the above instructions are executed individually or collectively by the at least one processor, the DU, Causing to refrain from determining the UAC barring factor and the UAC barring time based on the determination that the load of the CU indicated by the above CU load information is below a first threshold value, DU.

11. In a method performed by a DU (distributed unit), An operation to obtain CU load information from the CU that indicates the load of the CU (central unit) connected through the interface between the DU and F1; An operation to determine a UAC (unified access control) barring factor and a UAC barring time based on the load of the CU indicated by the CU load information; and The operation of transmitting a system information block (SIB) including the above UAC barring factor and the above UAC barring time to a user equipment (UE), method.

12. In Clause 11, the operation of determining the UAC barring factor and the UAC barring time is, An operation to determine whether the load of the CU indicated by the CU load information exceeds a first threshold value when the DU is operating in a normal load state; Based on the determination that the load of the above CU exceeds the above first threshold value: An operation to determine the UAC barring factor having the maximum level among predefined first levels and the UAC barring time having the minimum level among predefined second levels; and A method comprising an operation to change the UAC state of the above DU from the normal load state to the first overload state. method.

13. In Clause 11, the operation of determining the UAC barring factor and the UAC barring time is, An operation to determine whether, while the above DU is operating in a first overload state, the load of the CU indicated by the CU load information exceeds a second threshold value greater than the first threshold value; Based on the determination that the load of the above CU exceeds the above second threshold value: An operation to determine the UAC barring factor having a minimum level among predefined first levels and the UAC barring time having a maximum level among predefined second levels; and A method comprising an operation to change the UAC state of the above DU from the first overload state to the second overload state. method.

14. In Clause 13, the operation of determining the UAC barring factor and the UAC barring time is, An operation to determine whether the load of the CU exceeds a first value determined from the prior load of the CU, based on the determination that the load of the CU is less than or equal to the second threshold value; and The method includes determining the UAC barring factor having a level subsequent to the current level among the predefined first levels and the UAC barring time having a level subsequent to the current level among the predefined second levels, in accordance with the determination that the load exceeds the first value. The above first value is determined by adding an offset value to the above previous load, method.

15. In paragraph 13, the operation of determining the UAC barring factor and the UAC barring time is, An operation to determine whether the load of the CU is less than or equal to a second value determined from the previous load of the CU, based on the determination that the load of the CU is less than or equal to the second threshold value; and Based on the determination that the load is less than or equal to the second value, the operation includes determining the UAC barring factor having a level prior to the current level among the predefined first levels and the UAC barring time having a level prior to the current level among the predefined second levels, and The above second value is determined by subtracting the offset value from the above previous load, method.

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