KR20200014687A - Methods for load management of ran nodes and apparatueses thereof - Google Patents

Abstract

The present disclosure relates to a technique for managing a load on a base station node in a 5G network. According to an embodiment of the present invention, a method of a master base station for managing a secondary base station load comprises the steps of: configuring dual connectivity with the secondary base station; receiving a secondary base station status indication message from the secondary base station through an X2 interface; and determining whether to perform a load reduction operation for the secondary base station based on a value of a secondary base station load information parameter included in the secondary base station status indication message.

Description

METHODS FOR LOAD MANAGEMENT OF RAN NODES AND APPARATUESES THEREOF

The present disclosure relates to a technique for managing load on a base station node in a 5G network.

The next generation mobile communication technology is being researched according to the demand for large data processing and high speed data processing. For example, in the current mobile communication systems such as Long Term Evolution (LTE), LTE-Advanced, 5G, etc. of the 3GPP series, a high-speed, high-capacity communication system capable of transmitting and receiving various data such as video and wireless data beyond voice-oriented services This is required.

In order to process such a request, a terminal and a base station need a technique for transmitting and receiving data using a plurality of carriers. For example, a carrier merging technique in which one base station merges a plurality of carriers to communicate with a terminal, or a dual connectivity technique in which a plurality of base stations communicate with a terminal using a plurality of carriers, has been studied.

However, although the next generation wireless access technology is being developed, it is expected that a certain period of time is required to provide a communication service using only the base station utilizing the same. Therefore, even when the LTE base station using the conventional radio access technology and the NR base station using the next generation radio access technology coexist, it is necessary to provide a service through the aforementioned carrier merging or dual connectivity.

In addition, technology for base station load management has become important in a situation where the data usage of the terminal is rapidly increasing. In particular, in the case of base stations using heterogeneous access technology or in the case of transmitting data using a plurality of cells in a single base station, a technology for managing the load of individual base stations or individual cells by accurately recognizing the situation of each base station is required.

In the above background, the present disclosure is to propose a method and apparatus for load management of individual base stations when different base stations configure dual connectivity in the terminal.

In addition, the present disclosure is to propose a load management method and apparatus for each node when a plurality of logical nodes are configured in the base station.

According to an embodiment of the present invention, a method of managing a secondary base station load by a master base station includes: configuring dual connectivity with a secondary base station and transmitting a secondary base station status indication message from the secondary base station through an X2 interface. And determining whether to perform a load reduction operation on the secondary base station based on the receiving and the value of the secondary base station load information parameter included in the secondary base station status indication message.

In addition, an embodiment of the present invention provides a master base station for managing secondary base station loads, including a control unit constituting dual connectivity with the secondary base station and a receiving unit for receiving the secondary base station status indication message from the secondary base station through the X2 interface. It provides a master base station characterized in that whether to perform a load reduction operation for the secondary base station based on the value of the secondary base station load information parameter included in the secondary base station status indication message.

In addition, an embodiment is a method in which a central unit manages a load of a distributed unit, the method comprising: receiving a distributed unit status indication message from a distributed unit through an F1 interface, and a distributed unit status indication; And determining whether to perform a load reduction operation on the distribution unit based on the value of the distribution unit load information parameter included in the message.

In addition, one embodiment is a central unit for managing the load of the distributed unit (central unit), from the distribution unit through the F1 interface, to the receiving unit and the distribution unit status indication message for receiving the distribution unit status indication message It provides a central unit comprising a control unit for determining whether to perform a load reduction operation for the distributed unit based on the value of the distributed unit load information parameter included.

The present disclosure provides an effect of efficiently managing the load of individual base stations when different base stations configure dual connectivity in the terminal.

In addition, the present disclosure provides an effect of efficiently managing the load on each node when a plurality of logical nodes are configured in the base station.

1 is a diagram schematically illustrating a structure of an NR wireless communication system to which an embodiment of the present invention may be applied.
2 is a view for explaining a frame structure in an NR system to which the present embodiment can be applied.
3 is a view for explaining a dual connectivity structure to which the present embodiment can be applied.
4 is a flowchart illustrating an operation of a master base station according to an exemplary embodiment.
5 is a flowchart illustrating an operation of a master base station according to another embodiment.
6 is a signal diagram illustrating a procedure of transmitting a secondary base station status indication message according to an embodiment.
7 and 8 are signal diagrams for describing a procedure of transmitting a secondary base station status indication message according to another embodiment.
9 and 10 are signal diagrams for describing a procedure when a secondary base station status indication message transmission fails according to another embodiment.
11 is a diagram illustrating a resource state update procedure between different base stations.
12 is a diagram illustrating a dual connectivity structure in which a central unit and a distribution unit are divided according to an embodiment.
13 is a flowchart illustrating an operation of a central unit according to an exemplary embodiment.
14 is a signal diagram illustrating a procedure for transmitting a distributed unit status indication message according to an embodiment.
15 and 16 are signal diagrams for describing a distribution unit status indication message transmission procedure according to another embodiment.
17 and 18 are signal diagrams for describing a procedure in the case where transmission of a distributed unit base station status indication message according to another embodiment fails.
19 is a diagram illustrating a resource state update procedure between a distribution unit and a central unit.
20 is a diagram illustrating a master base station configuration according to an embodiment.
21 is a diagram illustrating a central unit configuration according to another embodiment.

Hereinafter, the present embodiments will be described in detail with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing this embodiment, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present embodiment, the detailed description thereof will be omitted.

In the present specification, the wireless communication system refers to a system for providing various communication services such as voice and packet data. The wireless communication system includes a user equipment (UE) and a base station (BS).

A user terminal is a comprehensive concept of a terminal in a wireless communication, and includes a user equipment (UE) in WCDMA, LTE, HSPA, and IMT-2020 (5G or New Radio), as well as a mobile station (MS) and a UT in GSM. It should be interpreted as a concept that includes a user terminal, a subscriber station (SS), and a wireless device.

A base station or cell generally refers to a station for communicating with a user terminal, and includes a Node-B, an evolved Node-B, an eNB, a gNode-B, and a Low Power Node. ), Sector, site, various types of antenna, base transceiver system (BTS), access point, access point (for example, transmission point, reception point, transmission / reception point), relay node ( It is meant to encompass various coverage areas such as relay nodes, mega cells, macro cells, micro cells, pico cells, femto cells, remote radio heads (RRHs), radio units (RUs), and small cells.

Since the various cells listed above have a base station for controlling each cell, the base station may be interpreted in two meanings. 1) the device providing the mega cell, the macro cell, the micro cell, the pico cell, the femto cell, the small cell in relation to the radio area, or 2) the radio area itself. In 1) all devices that provide a given wireless area are controlled by the same entity or interact with each other to cooperatively configure the wireless area to the base station. According to the configuration of the wireless area, a point, a transmission point, a transmission point, a reception point, and the like become one embodiment of a base station. In 2), the base station may indicate the radio area itself that receives or transmits a signal from a viewpoint of a user terminal or a neighboring base station.

In the present specification, a cell refers to a component carrier having coverage of a signal transmitted from a transmission / reception point or a signal transmitted from a transmission point or a transmission / reception point, and the transmission / reception point itself. Can be.

In the present specification, the user terminal and the base station are two (uplink or downlink) transmission and reception subjects used to implement the technology or the technical idea described in this embodiment, and are used in a comprehensive sense and limited by specific terms or words. It doesn't work.

Here, the uplink (Uplink, UL, or uplink) refers to a method for transmitting and receiving data to the base station by the user terminal, the downlink (Downlink, DL, or downlink) means to transmit and receive data to the user terminal by the base station It means the way.

The uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme that is transmitted using different times, and a frequency division duplex (FDD) scheme, a TDD scheme and a FDD scheme, which are transmitted using different frequencies. Mixed mode may be used.

In addition, in a wireless communication system, uplink and downlink are configured based on one carrier or a pair of carriers to configure a standard.

The uplink and the downlink transmit control information through a control channel such as a physical downlink control channel (PDCCH), a physical uplink control channel (PUCCH), a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), and the like. It is composed of the same data channel to transmit data.

Downlink (downlink) may mean a communication or communication path from the multiple transmission and reception points to the terminal, uplink (uplink) may mean a communication or communication path from the terminal to the multiple transmission and reception points. In this case, in the downlink, the transmitter may be part of multiple transmission / reception points, and the receiver may be part of the terminal. In addition, in uplink, a transmitter may be part of a terminal, and a receiver may be part of multiple transmission / reception points.

Hereinafter, a situation in which a signal is transmitted and received through a channel such as a PUCCH, a PUSCH, a PDCCH, and a PDSCH may be described in the form of 'sending and receiving a PUCCH, a PUSCH, a PDCCH, and a PDSCH.'

Meanwhile, high layer signaling described below includes RRC signaling for transmitting RRC information including an RRC parameter.

The base station performs downlink transmission to the terminals. The base station transmits downlink control information such as scheduling required for reception of a downlink data channel, which is a main physical channel for unicast transmission, and a physical downlink for transmitting scheduling grant information for transmission on an uplink data channel. The control channel can be transmitted. Hereinafter, the transmission and reception of signals through each channel will be described in the form of transmission and reception of the corresponding channel.

There is no limitation on the multiple access scheme applied in the wireless communication system. Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Code Division Multiple Access (CDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Non-Orthogonal Multiple Access (NOMA), OFDM-TDMA, OFDM-FDMA, Various multiple access techniques such as OFDM-CDMA can be used. Here, the NOMA includes a sparse code multiple access (SCMA) and a low density spreading (LDS).

One embodiment of the present embodiment is for resource allocation in the fields of asynchronous wireless communication evolving to LTE / LTE-Advanced, IMT-2020 via GSM, WCDMA, HSPA, and synchronous wireless communication evolving to CDMA, CDMA-2000 and UMB. Can be applied.

In the present specification, a MTC terminal may mean a terminal supporting low cost (or low complexity) or a terminal supporting coverage enhancement. Alternatively, in the present specification, the MTC terminal may mean a terminal defined in a specific category for supporting low cost (or low complexity) and / or coverage enhancement.

In other words, in the present specification, the MTC terminal may mean a newly defined 3GPP Release-13 low cost (or low complexity) UE category / type for performing LTE-based MTC related operations. Alternatively, in the present specification, the MTC terminal supports enhanced coverage compared to the existing LTE coverage, or UE category / type defined in the existing 3GPP Release-12 or less, or newly defined Release-13 low cost (or supporting low power consumption). low complexity) can mean UE category / type. Or, it may mean a further Enhanced MTC terminal defined in Release-14.

In the present specification, a NB-IoT (NarrowBand Internet of Things) terminal refers to a terminal that supports radio access for cellular IoT. The objectives of the NB-IoT technology include improved indoor coverage, support for large scale low speed terminals, low sensitivity, low cost terminal cost, low power consumption, and optimized network architecture.

After researching 4G (4th-Generation) communication technology, 3GPP develops 5G (5th-Generation) communication technology to meet the requirements of ITU-R's next generation wireless access technology. Specifically, 3GPP develops a new NR communication technology separate from LTE-A pro and 4G communication technology, which is an enhancement of LTE-Advanced technology to the requirements of ITU-R with 5G communication technology. LTE-A pro and NR both mean 5G communication technology.

In this specification, frequencies, frames, subframes, resources, resource blocks, regions, bands, subbands, control channels, data channels, synchronization signals, various reference signals, various signals, and various messages related to NR (New Radio). May be interpreted as meaning used in the past or present, or various meanings used in the future.

On the other hand, the term NR or 5G is described below to encompass a new generation of network technology that satisfies the above-mentioned 5G requirements. In addition, a radio access technology distinguished from NR is described as a conventional LTE technology.

5G network is divided into 5G core network (hereinafter referred to as 5GC, 5G CN, NGC, etc.) and 5G radio access network (hereinafter referred to as NG-RAN, 5G-RAN, etc.). The NG-RAN may consist of a set of 5G NBs (gNBs) that are one or more 5G base station nodes. The entity configuring the aforementioned core network may be referred to as a core network entity.

Meanwhile, the base station to which the 5G radio access technology is applied will be described as 5G base station, base station or NR base station, NG-RAN, gNB, etc., but is not limited to these terms. In addition, the base station to which the conventional LTE radio access technology is applied is described by describing it as a 4G base station, another base station or an LTE base station, eNB, etc., but is not limited to these terms.

Operational scenarios in NR defined various operational scenarios by adding considerations to satellites, automobiles, and new verticals in the existing 4G LTE scenarios.In terms of service, they have an eMBB (Enhanced Mobile Broadband) scenario and a high terminal density. Supports a range of mass machine communication (MMTC) scenarios that require low data rates and asynchronous connections, and Ultra Reliability and Low Latency (URLLC) scenarios that require high responsiveness and reliability and support high-speed mobility. .

In order to satisfy this scenario, NR discloses a wireless communication system using a new waveform and frame structure technology, low latency technology, mmWave support technology, and forward compatible technology. In particular, the NR system proposes various technological changes in terms of flexibility to provide forward compatibility. The main technical features of the NR will be described with reference to the drawings below.

<NR system general>

1 is a diagram briefly showing a structure of an NR system to which the present embodiment may be applied.

Referring to FIG. 1, an NR system is divided into a 5G core network (5GC) and an NG-RAN part, and the NG-RAN controls a user plane (SDAP / PDCP / RLC / MAC / PHY) and a user equipment (UE). It consists of gNB and ng-eNBs that provide planar (RRC) protocol termination. The gNB interconnects or gNBs and ng-eNBs are interconnected via an Xn interface. gNB and ng-eNB are each connected to 5GC through the NG interface. The 5GC may be configured to include an access and mobility management function (AMF) for controlling a control plane such as a terminal access and mobility control function, and a user plane function (UPF) for controlling a user data. NR includes support for sub-6 GHz frequency bands (FR1, Frequency Range 1) and 6 GHz and higher frequency bands (FR2, Frequency Range 2).

gNB means a base station that provides NR user plane and control plane protocol termination to the terminal, and ng-eNB means a base station that provides E-UTRA user plane and control plane protocol termination to the terminal. The base station described in the present specification should be understood to mean gNB and ng-eNB, and may be used to mean gNB or ng-eNB separately.

<NR waveform, pneumatic and frame structure>

In NR, a CP-OFDM waveform using a cyclic prefix is used for downlink transmission, and a CP-OFDM or DFT-s-OFDM is used for uplink transmission. OFDM technology is easy to combine with Multiple Input Multiple Output (MIMO), and has the advantage of using a low complexity receiver with high frequency efficiency.

On the other hand, in NR, since the requirements for data rate, delay rate, and coverage are different for each of the three scenarios described above, it is necessary to efficiently satisfy the requirements for each scenario through a frequency band constituting an arbitrary NR system. . To this end, a technique for efficiently multiplexing a plurality of different numerology-based radio resources has been proposed.

값이 2의 지수 값으로 사용되어 지수적으로 변경된다.Specifically, the NR transmission neuron is determined based on sub-carrier spacing and cyclic prefix (CP), based on 15khz as shown in Table 1 below.

The value is used as an exponential value of 2 and is changed exponentially.

Subcarrier spacing Cyclic prefix Supported for data Supported for synch 0 15 Normal Yes Yes One 30 Normal Yes Yes 2 60 Normal, Extended Yes No 3 120 Normal Yes Yes 4 240 Normal No Yes

As shown in Table 1 above, the NR's neuronality may be classified into five types according to the subcarrier spacing. This is different from the fixed subcarrier spacing of 15 kHz, one of the 4G communication technologies. Specifically, the subcarrier spacing used for data transmission in NR is 15, 30, 60, 120 kHz, and the subcarrier spacing used for synchronous signal transmission is 15, 30, 12, 240 kHz. In addition, extended CP applies only to 60kHz subcarrier spacing. On the other hand, the frame structure (frame) in NR is a frame having a length of 10ms consisting of 10 subframes having the same length of 1ms is defined. One frame may be divided into half frames of 5 ms, and each half frame includes five subframes. In the case of 15 kHz subcarrier spacing, one subframe consists of one slot, and each slot consists of 14 OFDM symbols. 2 is a view for explaining a frame structure in an NR system to which the present embodiment can be applied.

Referring to FIG. 2, the slot is fixedly configured with 14 OFDM symbols in the case of a normal CP, but the length of the slot may vary according to the subcarrier spacing. For example, in the case of pneumatics having a 15 kHz subcarrier spacing, the slot is configured to have a length equal to a subframe with a length of 1 ms. On the contrary, in the case of a numerology having a 30 kHz subcarrier spacing, the slot includes 14 OFDM symbols, but two slots may be included in one subframe with a length of 0.5 ms. That is, the subframe and the frame are defined with a fixed time length, the slot is defined by the number of symbols, the time length may vary according to the subcarrier interval.

Meanwhile, NR defines a basic unit of scheduling as a slot and also introduces a mini slot (or subslot or non-slot based schedule) to reduce transmission delay of a radio section. The use of a wide subcarrier spacing shortens the length of one slot inversely, thus reducing the transmission delay in the radio section. The mini slot (or sub slot) is for efficient support for the URLLC scenario and can be scheduled in units of 2, 4, and 7 symbols.

In addition, unlike LTE, NR defines uplink and downlink resource allocation at a symbol level in one slot. In order to reduce the HARQ delay, a slot structure capable of transmitting HARQ ACK / NACK in a transmission slot is defined, and this slot structure is described as a self-contained structure.

NR is designed to support a total of 256 slot formats, of which 62 slot formats are used in 3GPP Rel-15. In addition, the combination of various slots supports a common frame structure constituting an FDD or TDD frame. For example, a slot structure in which all symbols of a slot are set to downlink, a slot structure in which all symbols are set to uplink, and a slot structure in which downlink symbol and uplink symbol are combined are supported. NR also supports that data transmission is distributed and scheduled in one or more slots. Accordingly, the base station can inform the terminal whether the slot is a downlink slot, an uplink slot, or a flexible slot by using a slot format indicator (SFI). The base station may indicate the slot format by indicating an index of a table configured through UE-specific RRC signaling using SFI, and may indicate the slot format dynamically through DCI (Downlink Control Information) or statically through RRC. You can also specify quasi-statically.

In the present specification, both the base station using the LTE radio access technology and the base station using the NR radio access technology may be applied, and in particular, the dual connectivity situation between base stations using different radio access technologies will be described. Accordingly, the base station below may be an LTE base station or an NR base station, and if necessary, the base station is separately described.

This embodiment is a 5G wireless access network, non-standalone (NSA) network, standalone (SA) network, base station interworking interface, X2 interface / protocol, F1 interface / protocol, dual connectivity, EN-DC (E- UTRA-NR Dual Connectivity, base station and RAN load management, 5G user and control plane interfaces, NR and LTE protocols, and network multi-vendor interoperability (MVI).

Conventionally, load and overload management methods for various user sources between base station nodes or internal base station nodes supporting heterogeneous radio access technologies have not been considered. In particular, as a 5G network is newly introduced, NR base station interworking with an existing LTE base station is required in an NSA structure, and interworking between NR base stations is essential in an SA structure. In addition, interworking between a central unit (CU) and a distributed unit (DU), which are nodes within an NR base station, and interworking between the CU-CP and the CU-UP is also supported.

Proper load control is difficult because it cannot inform other nodes of the load and overload conditions associated with the 5G base station node. Thus, a malfunction of the base station system may occur and seriously affect the stability. Thus, design changes to the X2 and F1 control interfaces are needed to enable optimal load management in 5G base stations.

In particular, dual connectivity is that different base stations transmit and receive data using radio resources to the terminal, and may be applied to 5G networks.

3 is a view for explaining a dual connectivity structure to which the present embodiment can be applied.

Referring to FIG. 3, the master base station 310 and the secondary base station 320 interwork with each other through an X2 interface to provide radio resources to the terminal. In a dual connectivity situation, the secondary base station 320 provides only user plane data to the terminal. Therefore, the linkage with the core network is made through the S1-MME interface between the master base station 310 and the core network entity (ex, MME, 300).

That is, in the dual connectivity structure, the master base station 310 is associated with the core network entity 300, and the secondary base station 320 provides only user plane data to the terminal. As described above, in this case, the master base station 310 has a problem in that it is difficult to know the load state of the secondary base station 320. In particular, as described above, in the NSA of the 5G network, the radio access technologies of the master base station 310 and the secondary base station 320 are different, or in the case of the core network, different technologies may be used. Since a 5G terminal is likely to consume a large amount of data, load management of the secondary base station 320 may be more important when transmitting and receiving data to and from the terminal through a dual connectivity configuration.

Therefore, the following describes a procedure and a specific embodiment for load management of other base stations in the dual connectivity structure.

4 is a flowchart illustrating an operation of a master base station according to an exemplary embodiment.

Referring to FIG. 4, in a method of managing a secondary base station load, the master base station may perform a step of configuring dual connectivity with the secondary base station (S410). For example, the master base station may configure dual connectivity for the secondary base station and the terminal.

The master base station and the secondary base station herein can be set to use different radio access technologies. In addition, both the master base station and the secondary base station may be configured as a 5G base station. In addition, the master base station may be connected to the core network, the control plane and the user plane, and the secondary base station may be configured only the core network and the user plane connection.

For example, the master base station may be an eNB using LTE radio access technology, and the secondary base station configuring dual connectivity between the eNB and the terminal may be a gNB using NR radio access technology. As another example, the master base station may be a gNB using an NR radio access technology, and the secondary base station configuring dual connectivity between the gNB and a terminal may be an eNB using an LTE radio access technology. As another example, the master base station and the secondary base station may be configured to use the same radio access technology. For example, both base stations may be LTE base stations or NR base stations.

Meanwhile, the core network may be an EPC associated with an LTE base station or 5GC associated with an NR base station.

A detailed description of a method for configuring a secondary base station and dual connectivity by a master base station using different radio access technologies will be described later.

The master base station may perform the step of receiving the secondary base station status indication message from the secondary base station through the X2 interface (S420). For example, the master base station may receive the secondary base station status indication message from the secondary base station using the X2 protocol.

The secondary base station status indication message may be received periodically. Alternatively, the secondary base station status indication message may be triggered by the secondary base station when the preset trigger condition is satisfied. Alternatively, the secondary base station status indication message may be transmitted by the secondary base station at the request of the master base station and received by the master base station.

The secondary base station status indication message may include a message type parameter and a secondary base station load information parameter. The message type parameter may include a unique value specifying a procedure of the corresponding message, and the same message type parameter is applied in the same procedure. The secondary base station load information parameter may include one of a value indicating overload and a value indicating not overload.

For example, when the secondary base station is in an overloaded state, the secondary base station load information parameter may be set to a value (eg, overloaded) indicating overload. Alternatively, when the secondary base station is in a normal state (not an overload state), the secondary base station load information parameter may be set to a value (ex, not-overloaded) indicating that it is not overloaded. If necessary, the secondary base station load information parameter may be designated as a value indicating another state in addition to the above two values. For example, the secondary base station load information parameter may be set to any one of a steady state, a low load state, and an overload state. The value set in the secondary base station load information parameter is not limited, and may be set to any one of values for distinguishing N (N is a natural number of 2 or more).

The master base station may perform a step of determining whether to perform a load reduction operation on the secondary base station based on the value of the secondary base station load information parameter included in the secondary base station status indication message (S430).

When the master base station receives the secondary base station status indication message, the master base station checks the value of the secondary base station load information parameter. If the secondary base station load information parameter is set to a value indicating overload, the master base station may determine to start the load reduction operation for the secondary base station. On the contrary, when the secondary base station load information parameter is set to a value indicating that it is not overloaded, the master base station does not start the load reduction operation for the secondary base station.

The load reduction operation can be variously set by the base station operator, without limitation. For example, the load reduction operation may be an operation of reducing the amount of data delivered to the secondary base station. Alternatively, the load reduction operation may be an operation of limiting the number of dual connectivity radio bearers allocated to the secondary base station. Alternatively, the load reduction operation may be an operation of deactivating or releasing the dual connectivity configuration of the secondary base station.

Meanwhile, when the start of the load reduction operation is determined, the master base station may maintain the load reduction operation on the secondary base station until a secondary base station status indication message including a value indicating that it is not overloaded is received. For example, when the first secondary base station status indication message is set to a value indicating overload, the master base station initiates a load reduction operation. The master base station monitors the M-second secondary base station status indication message received after the above-described first secondary base station status indication message, and stops the load reduction operation when the secondary base station status indication message is set to a value indicating that it is not overloaded. .

Through this operation, the master base station can quickly and accurately acquire the load degree of the secondary base station on the X2 interface, and based on this, it is possible to efficiently manage the load of the secondary base station even when using different radio access technologies.

5 is a flowchart illustrating an operation of a master base station according to another embodiment.

Referring to FIG. 5, the master base station may configure dual connectivity with the secondary base station. Here, steps S510 and S520 may be included in step S410 or may be sequentially performed.

In detail, the master base station transmits an X2 interface setup request message including an entire serving cell list of the master base station to the secondary base station (S510). The master base station transmits an X2 interface setup request message for configuring dual connectivity to the candidate secondary base station for configuring dual connectivity at the terminal. In this case, list information about all serving cells provided by the master base station may be included in the X2 interface setup request message.

The master base station receives an X2 interface setup response message including the entire serving cell list of the secondary base station from the secondary base station (S520). After transmitting the X2 interface setup request message, the master base station receives the X2 interface setup response message including the entire serving cell list information of the secondary base station from the candidate secondary base station.

Thereafter, the master base station determines a secondary base station for configuring dual connectivity to the terminal based on the received X2 interface setup response message, and transmits configuration information necessary for configuring dual connectivity to the secondary base station to configure dual connectivity (S410).

In this way, the master base station may configure the dual connectivity by selecting a specific secondary base station to configure the dual connectivity in the terminal among the candidate secondary base station.

Hereinafter, various embodiments of the procedure for receiving the secondary base station status indication information will be divided and described. The following embodiment will be described based on the case where the master base station is an eNB and the secondary base station is a gNB for convenience of description, but the same may also be applied to the case where the base station is the opposite or the same radio access technology as described above.

6 is a signal diagram illustrating a procedure of transmitting a secondary base station status indication message according to an embodiment.

Referring to FIG. 6, the eNB 310 may receive a GNB STATUS INDICATION message from the gNB 320 through the X2 interface (S600). The GNB STATUS INDICATION message may include a message type parameter and a gNB load information parameter indicating load information of the gNB.

As described above, the gNB load information parameter may include any one of an overload value and a value indicating not overloading. Alternatively, the gNB load information parameter may include a value of any one of normal, overload and low load.

As shown in FIG. 6, the GNB STATUS INDICATION message may be received even without a separate request from the eNB 310. For example, the GNB STATUS INDICATION message may be transmitted and received according to a preset period. Alternatively, the GNB STATUS INDICATION message may be transmitted according to a result of the gNB 320 checking whether the transmission trigger is satisfied.

7 and 8 are signal diagrams for describing a procedure of transmitting a secondary base station status indication message according to another embodiment.

Referring to FIG. 7, the eNB 310 may transmit a resource status request message to the gNB 320 through the X2 interface (S700). That is, the eNB 310 may transmit a message for requesting load information of the gNB 320 if necessary.

When the gNB 320 receives the resource status request message, the gNB 320 transmits the resource status response message to the eNB 310 (S710). The resource status response message is transmitted through the X2 interface, and may include a message type parameter and a gNB load information parameter indicating load information of the gNB.

As described above, the gNB load information parameter may include any one of an overload value and a value indicating not overloading. Alternatively, the gNB load information parameter may include a value of any one of normal, overload and low load.

Referring to FIG. 8, the gNB 320 may transmit a resource status request message to the eNB 310 through the X2 interface (S800). That is, the gNB 320 may transmit a message for requesting load information of the gNB 310 if necessary.

When the eNB 310 receives the resource status request message, the eNB 310 transmits a resource status response message to the gNB 320 (S810). The resource status response message is transmitted through the X2 interface, and may include a message type parameter and an eNB load information parameter indicating load information of the eNB. The eNB load information parameter may include one of a value indicating overload and not overload. Alternatively, the eNB load information parameter may include a value of any one of normal, overload, and low load.

In this case, gNB 320 may be a master base station. Alternatively, the gNB 320 may be a case in which load state information of the secondary base station or the master base station is required.

9 and 10 are signal diagrams for describing a procedure when a secondary base station status indication message transmission fails according to another embodiment.

Referring to FIG. 9, the eNB 310 may transmit a resource status request message to the gNB 320 through the X2 interface (S900). That is, the eNB 310 may transmit a message for requesting load information of the gNB 320 if necessary.

When the gNB 320 receives the resource status request message, the gNB 320 checks whether a response to the request message is possible. If the resource status information according to the request message cannot be provided, the gNB 320 transmits a resource status failure message to the eNB 310 (S910). The resource status failure message is delivered through the X2 interface and may include a message type parameter and a cause parameter that cannot provide load information of the gNB.

Referring to FIG. 10, the gNB 320 may transmit a resource status request message to the eNB 310 through the X2 interface (S1000). That is, the gNB 320 may transmit a message for requesting load information of the gNB 310 if necessary.

When the eNB 310 receives the resource status request message, the eNB 310 checks whether resource status information can be provided. If the resource status information according to the request message cannot be provided, the eNB 310 transmits a resource status failure message to the gNB 320 (S1010). The resource status failure message is transmitted through the X2 interface, and may include a message type parameter and a cause parameter that cannot provide load information of the eNB.

11 is a diagram illustrating a resource state update procedure between different base stations.

Referring to FIG. 11, the eNB 310 may receive a resource status update message from the gNB 320 through the X2 interface (S1100). The resource status update message may include a message type parameter and a gNB load information parameter indicating load information of the gNB.

In contrast, the gNB 320 may receive a resource status update message from the eNB 310 through the X2 interface (S1110). The resource status update message may include a message type parameter and an eNB load information parameter indicating load information of the eNB.

As described above, the eNB load information parameter and the gNB load information parameter may include any one of a value indicating overload and not overload. Alternatively, the eNB load information parameter and the gNB load information parameter may include values of any one of normal, overload, and low load.

In the case of FIG. 11, the process of FIG. 6 is performed by each of the base stations 310 and 320. That is, the steps of S1100 and S1110 may be performed separately in any order. Alternatively, when the eNB 310 receives a message according to step S1100, the eNB 310 may perform step S1110. Alternatively, when the message according to step S1110 is received, the gNB 320 may transmit the message in the same manner as in step S1100. That is, each base station (310, 320) may receive the load information of the other base station (320, 310), may transmit its own load information.

The name of each message and the name of the parameter described with reference to FIGS. 6 to 11 are exemplary and not limited thereto. The following further describes various embodiments of the aforementioned operations and parameters in terms of each message.

1) Resource Status Request Message

As described above, the eNB may send a RESOURCE STATUS REQUEST message to the gNB (or gNB to the eNB). The RESOURCE STATUS REQUEST message may include eNB Measurement ID and gNB Measurement ID, which are load measurement identifiers for eNB and gNB, as parameters.

gNB-CU Measurement ID, gNB-CU-CP Measurement ID, gNB-CU-UP Measurement ID, gNB-DU Measurement ID, gNB-RU Each Measurement ID may be used. Similarly, eNB DU, eNB-DU Measurement ID and eNB-RU Measurement ID, which are load measurement identifiers for RU, may be used.

Measurement IDs of the eNB and gNB may be separated / divided into IDs corresponding to the load associated with the LTE terminal and the load associated with the NSA terminal, respectively. For example, it may be classified into four types: eNB Measurement ID for LTE and eNB Measurement ID for NSA, gNB Measurement ID for LTE, and gNB Measurement ID for NSA.

Alternatively, only measurement IDs of the eNB may be separated / divided into IDs corresponding to loads associated with the LTE terminal and loads associated with the NSA terminal, respectively. For example, it may be divided into eNB Measurement ID for LTE and eNB Measurement ID for NSA.

RESOURCE STATUS REQUEST message contains LTE cell or NR cell information, cell frequency and bandwidth, LTE and NR component carrier used, available throughput (or data rate) per cell, available throughput (or data rate) rate And information indicating whether a licensed / unlicensed / shared band is present.

Load information of each base station can be measured for each connected bearer or for each bearer type. For example, each base station can calculate the load for each MCG bearer, SCG split bearer, SCG bearer type. Alternatively, the load information may be measured for each frequency or for each frequency used in the NR gNB. For example, load calculation is possible for each 3.5 GHz frequency and 28 GHz frequency. Alternatively, when simultaneously used for LTE and NR in the same frequency band, it is possible to measure the load of the sum of these frequencies.

2) Resource Status Response Message

If the gNB can provide the requested load status and information from the eNB (or the eNB from the gNB), the gNB measures / calculates the corresponding information and reports it through a RESOURCE STATUS RESPONSE message.

For example, through the resource status response message, each base station can indicate whether load information of all or part of the request can be provided, and includes a list of available information and an impossible list.

In addition, the resource status response message may include the calculated load information or information indicating whether or not overloaded as described above.

3) Resource status failure message

If the gNB cannot provide the requested load status and information from the eNB (or the eNB from the gNB), each base station notifies the eNB (or gNB) through a RESOURCE STATUS FAILURE message. The RESOURCE STATUS FAILURE message may include information indicating the cause of failure of providing load information.

4) Resource Status Update Message

The gNB updates the load status and information provisions to the eNB (or eNB to gNB) via a RESOURCE STATUS UPDATE message. It can be updated or periodically updated according to a specific event, and in the case of periodic update, an update cycle is set.

The load information used at the base station (eNB and gNB) of the NSA includes all or part of the following:

5) NR gNB related load information

The load information transmitted by the gNB may include at least one of the following information.

Cell unit load (DL, UL, DU + UL, SUL) information

Frequency unit load information

Terminal unit load (NSA terminal, SA terminal) information

-NR CA connections and NR CA load information

at least one of total load information, CP processing load information, UP processing load information, and VM load information of the gNB;

at least one of total load, CP processing load, UP processing load and VM load of the gNB CU. However, when a CU is divided into CU-CP and CU-UP, CU-CP load, CU-UP load, CU-CP VM load, and CU-CP VM load can be added / replaced.

at least one of gross load, CP processing load, UP processing load and VM load of the gNB DU. However, load information when RU is included and RU is not included is available.

at least one of gNB RU's total load, CP processing load, UP processing load and VM load

at least one of transmission network load and transmission delay information between the gNB and the eNB;

at least one of transmission network load and transmission delay information between gNB and gNB;

at least one of transmission network load and transmission delay information between gNB CU-DUs;

at least one of transmission network load and transmission delay information between gNB DU-RUs;

At least one of a start time, an end time, and a duration of each load state;

6) LTE eNB related load information

The load information transmitted by the eNB may include at least one of the following information.

Cell unit load (DL, UL, DU + UL, SUL) information

Frequency unit load information

Terminal unit load (NSA terminal, SA terminal) information

LTE CA connection count and LTE CA load information

at least one of total load, CP processing load, UP processing load, and VM load of the eNB;

at least one of the total load, CP processing load, UP processing load and VM load of the eNB DU. However, load information when RU is included and RU is not included is available.

at least one of total load, CP processing load, UP processing load, and VM load of the eNB RU;

at least one of transmission network load and transmission delay between the eNB and the eNB;

at least one of transmission network load and transmission delay between eNB DU-RUs;

At least one of a start time, an end time, and a duration of each load state;

On the other hand, the above-described load state can be classified qualitatively or quantitatively as follows, and may be configured by a combination of some / all of them.

1) Low, Medium, High, Critical

2) Normal, Overloaded

3) Not Overloaded, Overloaded

4) Underloaded, Normal, Overloaded

5) Relative level value of the load (eg no load 0 to maximum load 100)

6) Percent of relative percentage of load (eg lowest 0% to maximum 100%)

7) Numeric value of the relevant status value (e.g. CA connection number, VM number, etc.)

Through the above-described operation, the master base station may perform load management by obtaining load information of the secondary base station. Hereinafter, an embodiment in which the above-described operation is applied to load management between logical nodes of a 5G base station (gNB) will be described.

12 is a diagram illustrating a dual connectivity structure in which a central unit and a distribution unit are divided according to an embodiment.

Referring to FIG. 12, a 5G network is divided into a core network (CN 300), an NR, and / or an LTE radio access network (RAN). The terminal assumes a dual-mode terminal capable of connecting to both the NR base station 1220 + 1250 and the LTE base station 310.

The core network 300 is divided into control plane (CP) 1210 and user plane (UP) 1215 functions, respectively, CN-CP (1210, ex, MME / AMF / SMF) and CN-. UP 1215, ex, SGW / PGW / UPF. The interface between the CN-CP 1210 and the CN-UP 1215 device is connected via a standardized interface.

In addition, the interface between the CN 300 and the NR / LTE base station is linked to the S1 interface upgraded to support NSA or NG (or N2) interface capable of SA support.

The NR base station 1220 + 1250 or the LTE base station 310 may be a master base station according to the operator's wireless network construction scenario and the use frequency characteristic. As described above, it is assumed here that the eNB 310 is a master base station. The master base station 310 is connected to the CN-CP 1210 device and the S1-C / NG-C interface, and the CN-UP 1215 device and the S1-U / NG-U interface, respectively.

Meanwhile, an interface directly connected for interworking between the NR base station 1220 + 1225 and the LTE base station 310 is defined as X2 (or X2 EN-DC). The X2 interface can be viewed as an inter-RAT interworking interface between the NR and the LTE base station, and is required to support the mobility of the radio section and the multiple connections between the NR and the LTE base station.

The CU node 1220 of the NR base station may be further separated into a CU-CP node 1222 and a CU-UP node 1221, which are interworked with an E1 control interface. In addition, the NR base station is divided into a CU node 1220 and a DU node 1250, which are interworked with the F1-C and F1-U interfaces. Here, the NR gNB DU 1250 may be a node including all of the RLC, MAC, and PHY, or may be separated from the RU node to include a part of the RLC, MAC, and PHY. For example, the DU 1250 may be configured to include an RLC and a MAC, and the RU may include a PHY. In addition, the LTE eNB 310 may integrate or separate a digital unit (DU) and a radio unit (RU) node.

Meanwhile, the 5G NSA network is composed of an LTE base station 310 and an NR base station 1220 + 1225 supporting various frequencies. That is, when the cell and the base station node having a low load can be selected, the throughput of the terminal can be improved and stable network operation can be performed.

In addition, when the configuration base station function is mounted and operated on the virtualization system, processing performance is affected according to the VM (Virtual Machine) load, CP processing load, UP processing load, and inter-node transport network load of the corresponding node. Load balancing can also improve performance.

Accordingly, load management between the gNB CU 1220 and the DU 1250 may also be needed. In this case, the above-described state indication operation on the X2 interface can be changed and applied. The terms of the status indication message and the parameters of the following are exemplary and not limited, and may be variously modified as necessary.

13 is a flowchart illustrating an operation of a central unit according to an exemplary embodiment.

Referring to FIG. 13, in a method of managing a load of a distributed unit, the central unit may perform a step of receiving a distributed unit status indication message from the distributed unit through the F1 interface. (S1310).

As described above, the base station may be composed of one central unit and one or more distribution units. In addition, the central unit is a logical node hosting Radio Resource Control (RRC) and Packet Data Convergence Protocol (PDCP) of the base station. The distributed unit is a logical node hosting Radio Link Control (RLC), Medium Access Control (MAC) and Physical (PHY) layers of the base station.

The distributed unit status indication message may be received periodically. Alternatively, the distributed unit status indication message may be triggered to be transmitted from the distributed unit when a preset trigger condition is satisfied. Alternatively, the distributed unit status indication message may be transmitted by the distributed unit at the request of the central unit and received by the central unit.

The distributed unit status indication message may include a message type parameter, a transaction identification parameter, and a distributed unit load information parameter. The message type parameter indicates the type of the message. The Transaction ID parameter is used to uniquely identify the procedure among all ongoing parallel procedures of the same type initiated by the same protocol peer. same type initiated by the same protocol peer). Messages belonging to the same procedure use the same transaction identification parameter (Messages belonging to the same procedure shall use the same Transaction ID). The Transaction ID is determined by the initiating peer of a procedure.

The distributed unit load information parameter may include one of a value indicating overload and a value indicating not overload.

For example, when the distributed unit is in an overloaded state, the distributed unit load information parameter may be set to a value indicating an overload (ex, overloaded). Alternatively, when the distributed unit is in a normal state (not an overload state), the distributed unit load information parameter may be set to a value (ex, not-overloaded) indicating that it is not overloaded. If necessary, the distributed unit load information parameter may be designated as a value indicating another state in addition to the above two values. For example, the distributed unit load information parameter may be set to any one of a steady state, a low load state, and an overload state. The value set in the distributed unit load information parameter is not limited, and may be set to any one of values for distinguishing N (N is a natural number of two or more).

The central unit may perform a step of determining whether to perform a load reduction operation on the distribution unit based on the value of the distribution unit load information parameter included in the distribution unit status indication message (S1320).

When the central unit receives the distributed unit status indication message, the central unit checks the value of the distributed unit load information parameter. If the distributed unit load information parameter is set to a value indicating overload, the central unit may determine to start the load reduction operation for the distributed unit. On the contrary, when the distributed unit load information parameter is set to a value indicating that it is not overloaded, the central unit does not start the load reduction operation for the distributed unit.

The load reduction operation can be variously set by the base station operator, without limitation. For example, the load reduction operation may be an operation of reducing the amount of data transferred to the distribution unit. Alternatively, the load reduction operation may be an operation of limiting the number of radio bearers allocated to the distribution unit. Alternatively, the load reduction operation may be an operation of deactivating or releasing a configuration of the distribution unit.

On the other hand, when the start of the load reduction operation is determined, the central unit may maintain the load reduction operation on the distribution unit until a distribution unit status indication message including a value indicating that it is not overloaded is received. For example, when the first distribution unit status indication message is set to a value indicating overload, the central unit starts the load reduction operation. The central unit monitors the Mth distributed unit status indication message received after the first distributed unit status indication message described above, and stops the load reduction operation when the distributed unit status indication message is set to a value indicating that it is not overloaded. .

Through this operation, the central unit can quickly and accurately acquire the load of the distributed unit on the F1 interface, thereby efficiently managing the load of the distributed unit.

14 is a signal diagram illustrating a procedure for transmitting a distributed unit status indication message according to an embodiment.

Referring to FIG. 14, the gNB-DU 1250 may transmit a GNB-DU STATUS INDICATION message to the gNB-CU 1220 through the F1 interface (S1400). The GNB-DU STATUS INDICATION message may include a message type parameter, a transaction ID parameter, and a distributed unit load information parameter indicating load information of the gNB-DU.

As described above, the distributed unit load information parameter may include any one of an overload value and a value indicating not overloading. Alternatively, the distributed unit load information parameter may include any one of normal, overload and low load.

As shown in FIG. 14, the GNB-DU STATUS INDICATION message may be received even without a separate request from the gNB-CU 1220. For example, the GNB-DU STATUS INDICATION message may be transmitted and received according to a preset period. Alternatively, the GNB-DU STATUS INDICATION message may be transmitted according to a result of the gNB-DU 1250 checking whether the transmission trigger is satisfied.

15 and 16 are signal diagrams for describing a distribution unit status indication message transmission procedure according to another embodiment. Here, the distributed unit status indication message will be described as a resource status response message.

Referring to FIG. 15, the gNB-CU 1220 may transmit a resource status request message to the gNB-DU 1250 through the F1 interface (S1500). That is, the gNB-CU 1220 may transmit a message for requesting load information of the gNB-DU 1250 if necessary.

When the gNB-DU 1250 receives the resource status request message, the gNB-DU 1250 transmits a resource status response message to the gNB-CU 1220 (S1510). The resource status response message is transmitted through the F1 interface and may include a message type parameter, a transaction identification parameter, and a distribution unit load information parameter indicating load information of the gNB-DU.

As described above, the distributed unit load information parameter may include any one of an overload value and a value indicating not overloading. Alternatively, the distributed unit load information parameter may include any one of normal, overload and low load.

Referring to FIG. 16, the gNB-DU 1250 may transmit a resource status request message to the gNB-CU 1220 through the F1 interface (S1600). That is, the gNB-DU 1250 may transmit a message for requesting load information of the gNB-CU 1220 if necessary.

When the gNB-CU 1220 receives the resource status request message, the gNB-CU 1220 transmits a resource status response message to the gNB-DU 1250 (S1610). The resource status response message is delivered through the F1 interface, and may include a message type parameter, a transaction identification parameter, and a central unit load information parameter indicating load information of the eNB-CU. The central unit load information parameter may include any one of an overload value and a value indicating not overloading. Alternatively, the eNB central unit information parameter may include a value of any one of normal, overload, and low load.

17 and 18 are signal diagrams for describing a procedure in the case where transmission of a distributed unit base station status indication message according to another embodiment fails.

Referring to FIG. 17, the gNB-CU 1220 may transmit a resource status request message to the gNB-DU 1250 through the F1 interface (S1700). That is, the gNB-CU 1220 may transmit a message for requesting load information of the gNB-DU 1250 if necessary.

When the gNB-DU 1250 receives the resource status request message, the gNB-DU 1250 checks whether a response to the request message is possible. If the resource status information according to the request message cannot be provided, the gNB-DU 1250 transmits a resource status failure message to the gNB-CU 1220 (S1710). The resource status failure message is delivered through the F1 interface and may include a message type parameter, a transaction identification parameter, and a cause parameter that cannot provide load information of the gNB-DU 1250.

Referring to FIG. 18, the gNB-DU 1250 may transmit a resource status request message to the gNB-CU 1220 through the F1 interface (S1800). That is, the gNB-DU 1250 may transmit a message for requesting load information of the gNB-CU 1220 if necessary.

The gNB-CU 1220 checks whether resource status information is available when the resource status request message is received. If the resource status information according to the request message cannot be provided, the gNB-CU 1220 transmits a resource status failure message to the gNB-DU 1250 (S1810). The resource status failure message is delivered through the F1 interface and may include a message type parameter, a transaction identification parameter, and a cause parameter that cannot provide load information of the gNB-CU 1220.

19 is a diagram illustrating a resource state update procedure between a distribution unit and a central unit.

Referring to FIG. 19, the gNB-CU 1220 may receive a resource status update message from the gNB-DU 1250 through the F1 interface (S1900). The resource status update message may include a message type parameter, a transaction identification parameter, and a distributed unit load information parameter indicating load information of the gNB-DU 1250.

In contrast, the gNB-DU 1250 may receive a resource status update message from the gNB-CU 1220 through the F1 interface (S1910). The resource status update message may include a message type parameter, a transaction identification parameter, and a central unit load information parameter indicating load information of the gNB-CU 1220.

As described above, the central unit load information parameter and the distributed unit load information parameter may include any one of a value indicating overload and not overload. Alternatively, the central unit load information parameter and the distributed unit load information parameter may include any one of normal, overload and low load.

In the case of FIG. 19, the process of FIG. 14 is performed by each of the nodes 1220 and 1250. That is, the steps of S1900 and S1910 may be performed separately in any order. Alternatively, if the message according to step S1900 is received, the gNB-CU 1220 may perform step S1910. Alternatively, when the message according to step S1910 is received, the gNB-DU 1250 may transmit the message in the same manner as in step S1900. That is, each node 1220 and 1250 may transmit its own load information when receiving the load information of the other nodes 1250 and 1220.

The name of each message and the name of the parameter described with reference to FIGS. 14 to 19 are exemplary and not limited thereto. The following describes the above-described operation and various embodiments in terms of each message and parameter.

1) Resource Status Request Message

The CU sends a RESOURCE STATUS REQUEST message to the DU (or the DU to the CU) to request reporting of the load status and information of the DU (or CU).

gNB-CU Measurement ID, gNB-CU-CP Measurement ID, gNB-CU-UP Measurement ID, gNB-DU Measurement ID, gNB-RU which are load measurement identifiers for gNB CU, CU-CP, CU-UP, DU, RU Each measurement ID is used. In addition, the measurement IDs of the gNB presented above may be separated / divided into IDs corresponding to loads associated with the SA terminal and loads associated with the NSA terminal. For example, it may be divided into gNB Measurement ID for SA and gNB Measurement ID for NSA.

RESOURCE STATUS REQUEST messages contain NR cell information and include cell frequency and bandwidth, NR component carrier used, available throughput (or data rate) per cell, available throughput (or data rate) rate, and licensed. It may include at least one information of whether / unlicensed / shared band.

Load information can be measured for all connected bearers or for each bearer type. For example, load calculation is possible for each MCG bearer, SCG split bearer, and SCG bearer type. Alternatively, the load information may be measured for each frequency or for each frequency used in the NR gNB. For example, load calculations are available for the 3.5 GHz and 28 GHz frequencies. In addition, when used simultaneously for LTE and NR in the same frequency band, it is also possible to measure the load of the sum of these frequencies.

2) Resource status response message (distribution unit status indication message)

If the DU can provide the requested load status and information from the CU (or the CU from the DU), the DU measures and calculates the information and reports it to the CU (or DU) through the RESOURCE STATUS RESPONSE message.

The RESOURCE STATUS RESPONSE message may include information indicating whether all or part of the requested load information is available, and may include a list of available information and an impossible list.

3) Resource status failure message

If the DU is unable to provide the requested load status and information from the CU (or the CU from the DU), the DU notifies the CU (or DU) through the RESOURCE STATUS FAILURE message. The RESOURCE STATUS FAILURE message may include a cause parameter indicating a load state and a reason for failing to provide load information.

4) Resource Status Update Message

The DU updates the load status and information provisions to the CU (or CU to DU) via the RESOURCE STATUS UPDATE message. It can be updated or periodically updated according to a specific event, and in the case of periodic update, an update cycle is set.

The aforementioned messages are the F1 interface based load management method between the gNB CU and the DU, and are equally applicable to the SA network.

5) NR gNB related load information

The load information transmitted by the gNB-DU or gNB-CU may include at least one of the following information.

Cell unit load (DL, UL, DU + UL, SUL) information

Frequency unit load information

Terminal unit load (NSA terminal, SA terminal) information

-NR CA connections and NR CA load information

at least one of total load information, CP processing load information, UP processing load information, and VM load information of the gNB;

at least one of total load, CP processing load, UP processing load and VM load of the gNB CU. However, when a CU is divided into a CU-CP and a CU-UP, a CU-CP load, a CU-UP load, a CU-CP VM load, and a CU-CP VM load may be added / replaced.

at least one of gross load, CP processing load, UP processing load and VM load of the gNB DU. However, load information when RU is included and RU is not included is available.

at least one of gNB RU's total load, CP processing load, UP processing load and VM load

at least one of transmission network load and transmission delay information between the gNB and the eNB;

at least one of transmission network load and transmission delay information between gNB and gNB;

at least one of transmission network load and transmission delay information between gNB CU-DUs;

at least one of transmission network load and transmission delay information between gNB DU-RUs;

At least one of a start time, an end time, and a duration of each load state;

On the other hand, the above-described load state can be classified qualitatively or quantitatively as follows, and may be configured by a combination of some / all of them.

1) Low, Medium, High, Critical

2) Normal, Overloaded

3) Not Overloaded, Overloaded

4) Underloaded, Normal, Overloaded

5) Relative level value of the load (eg no load 0 to maximum load 100)

6) Percent of relative percentage of load (eg lowest 0% to maximum 100%)

7) Numeric value of the relevant status value (e.g. CA connection number, VM number, etc.)

As described above, according to the present disclosure, efficient load management between base stations or base station nodes may be performed in a 5G radio access network supporting heterogeneous radio technologies. In addition, this load management provides more reliable connectivity and transmission speeds and can significantly reduce the cost of building and operating wireless networks.

Hereinafter, with reference to the drawings focusing on the configuration of the above-described master base station and the central unit.

20 is a diagram illustrating a master base station configuration according to an embodiment.

Referring to FIG. 20, the master base station 2000 includes a control unit 2010 constituting dual connectivity with the secondary base station and a receiving unit 2030 that receives the secondary base station status indication message from the secondary base station through the X2 interface. The controller 2010 may determine whether to perform a load reduction operation on the secondary base station based on the value of the secondary base station load information parameter included in the secondary base station status indication message.

For example, the master base station 2000 may configure dual connectivity for the secondary base station and the terminal. For example, the master base station 2000 may be an eNB using an LTE radio access technology, and the secondary base station configuring dual connectivity between the eNB and the UE may be a gNB using NR radio access technology. As another example, the master base station 2000 may be a gNB using NR radio access technology, and the secondary base station configuring dual connectivity at the gNB and a terminal may be an eNB using LTE radio access technology. As another example, the master base station 2000 and the secondary base station may be configured to use the same radio access technology.

The secondary base station status indication message may be received periodically. Alternatively, the secondary base station status indication message may be triggered by the secondary base station when the preset trigger condition is satisfied. Alternatively, the secondary base station status indication message may be transmitted by the secondary base station at the request of the master base station 2000 and received by the receiver 2030.

The secondary base station status indication message may include a message type parameter and a secondary base station load information parameter. The message type parameter may include a unique value specifying a procedure of the corresponding message, and the same message type parameter is applied in the same procedure. The secondary base station load information parameter may include one of a value indicating overload and a value indicating not overload.

For example, when the secondary base station is in an overloaded state, the secondary base station load information parameter may be set to a value (eg, overloaded) indicating overload. Alternatively, when the secondary base station is in a normal state (not an overload state), the secondary base station load information parameter may be set to a value (ex, not-overloaded) indicating that it is not overloaded. If necessary, the secondary base station load information parameter may be designated as a value indicating another state in addition to the above two values.

When the secondary base station status indication message is received, the controller 2010 checks the value of the secondary base station load information parameter. If the secondary base station load information parameter is set to a value indicating overload, the controller 2010 may determine to start the load reduction operation for the secondary base station. On the contrary, when the secondary base station load information parameter is set to a value indicating that the secondary base station load information parameter is not overloaded, the controller 2010 does not start the load reduction operation for the secondary base station.

The load reduction operation can be variously set by the base station operator, without limitation. For example, the load reduction operation may be an operation of reducing the amount of data delivered to the secondary base station. Alternatively, the load reduction operation may be an operation of limiting the number of dual connectivity radio bearers allocated to the secondary base station. Alternatively, the load reduction operation may be an operation of deactivating or releasing the dual connectivity configuration of the secondary base station.

Meanwhile, when the start of the load reduction operation is determined, the controller 2010 may maintain the load reduction operation on the secondary base station until a secondary base station status indication message including a value indicating that it is not an overload is received.

In addition, the transmitter 2020 transmits an X2 interface setup request message including the entire serving cell list of the master base station to the secondary base station. The transmitter 2020 transmits an X2 interface setup request message for configuring dual connectivity to a candidate secondary base station for configuring dual connectivity. In this case, list information about all serving cells provided by the master base station 2000 may be included in the X2 interface setup request message.

The receiving unit 2030 receives an X2 interface setup response message including the entire serving cell list of the secondary base station from the secondary base station. After transmission of the X2 interface setup request message, the receiver 2030 receives an X2 interface setup response message including the entire serving cell list information of the secondary base station from the candidate secondary base station.

Thereafter, the controller 2010 determines a secondary base station for configuring dual connectivity to the terminal based on the received X2 interface setup response message, and configures dual connectivity by controlling configuration information necessary for dual connectivity to be transmitted to the secondary base station. .

In addition, the controller 2010 generally controls the operations of the master base station 2000 required to perform the operations for the secondary base station load management according to the present embodiment.

In addition, the transmitter 2020 and the receiver 2030 are used to transmit and receive signals, messages, and data necessary for performing the above-described embodiments with other base stations and terminals.

21 is a diagram illustrating a central unit configuration according to another embodiment.

Referring to FIG. 21, a central unit 2100 managing a load of a distributed unit includes a receiver 2130 and a distributed unit state that receive a distributed unit status indication message from the distributed unit through an F1 interface. The controller 2110 may determine whether to perform a load reduction operation on the distributed unit based on the value of the distributed unit load information parameter included in the indication message.

Referring to FIG. 21, a base station may be configured with one central unit 2100 and one or more distribution units. In addition, the central unit 2100 is a logical node hosting Radio Resource Control (RRC) and Packet Data Convergence Protocol (PDCP) of the base station. The distributed unit is a logical node hosting Radio Link Control (RLC), Medium Access Control (MAC) and Physical (PHY) layers of the base station.

The receiver 2130 may periodically receive the distributed unit status indication message. Alternatively, the distributed unit status indication message may trigger transmission in the distributed unit when a preset trigger condition is satisfied. Alternatively, the distributed unit status indication message may be transmitted by the distributed unit at the request of the central unit 2000 and received by the central unit 2000.

The distributed unit status indication message may include a message type parameter, a transaction identification parameter, and a distributed unit load information parameter. The message type parameter indicates the type of the message. The Transaction ID parameter is used to uniquely identify the procedure among all ongoing parallel procedures of the same type initiated by the same protocol peer. same type initiated by the same protocol peer). Messages belonging to the same procedure use the same transaction identification parameter (Messages belonging to the same procedure shall use the same Transaction ID). The Transaction ID is determined by the initiating peer of a procedure.

The distributed unit load information parameter may include one of a value indicating overload and a value indicating not overload. For example, when the distributed unit is in an overloaded state, the distributed unit load information parameter may be set to a value indicating an overload (ex, overloaded). Alternatively, when the distributed unit is in a normal state (not an overload state), the distributed unit load information parameter may be set to a value (ex, not-overloaded) indicating that it is not overloaded. If necessary, the distributed unit load information parameter may be designated as a value indicating another state in addition to the above two values.

When the distribution unit status indication message is received, the control unit 2110 checks the value of the distribution unit load information parameter. If the distributed unit load information parameter is set to a value indicating overload, the controller 2110 may determine to start the load reduction operation for the distributed unit. On the contrary, when the distributed unit load information parameter is set to a value indicating that the overload is not overloaded, the controller 2110 does not start a load reduction operation on the distributed unit. The load reduction operation can be variously set by the base station operator, without limitation. Meanwhile, when it is determined that the load reduction operation is started, the controller 2110 may maintain the load reduction operation on the distribution unit until the distribution unit status indication message including a value indicating that the load reduction operation is not received is received.

In addition, the controller 2110 generally controls the operations of the central unit 2100 required to perform the operations for the distributed unit load management according to the present embodiment.

In addition, the transmitter 2120 and the receiver 2130 are used to transmit and receive signals, messages, and data necessary for performing the above-described embodiments with a distribution unit, a core network entity, other base stations and terminals.

The above-described embodiments may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802, 3GPP and 3GPP2. That is, steps, components, and parts which are not described in order to clearly reveal the present technical spirit of the embodiments may be supported by the aforementioned standard documents. In addition, all terms disclosed herein may be described by the standard documents disclosed above.

The above-described embodiments may be implemented through various means. For example, the embodiments may be implemented by hardware, firmware, software, or a combination thereof.

In the case of a hardware implementation, the method according to the embodiments may include one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), FPGAs. (Field Programmable Gate Arrays), a processor, a controller, a microcontroller or a microprocessor may be implemented.

In the case of an implementation by firmware or software, the method according to the embodiments may be implemented in the form of an apparatus, a procedure, or a function that performs the functions or operations described above. The software code may be stored in a memory unit and driven by a processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

In addition, the terms "system", "processor", "controller", "component", "module", "interface", "model", or "unit" described above generally refer to computer-related entity hardware, hardware and software. May mean a combination of, software or running software. For example, the aforementioned components may be, but are not limited to, a process driven by a processor, a processor, a controller, a control processor, an object, an execution thread, a program, and / or a computer. For example, both an application running on a controller or processor and a controller or processor can be components. One or more components may be within a process and / or thread of execution, and the components may be located on one device (eg, system, computing device, etc.) or distributed across two or more devices.

The above description is merely illustrative of the technical idea of the present disclosure, and various modifications and variations may be made by those skilled in the art without departing from the essential characteristics of the present disclosure. In addition, the present embodiments are not intended to limit the technical spirit of the present disclosure but to describe the scope of the present inventive concept. The scope of protection of the present disclosure should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto shall be construed as being included in the scope of the present disclosure.

Claims (20)

In the method for the master base station to manage the secondary base station load,
Configuring dual connectivity with the secondary base station;
Receiving a secondary base station status indication message from the secondary base station through an X2 interface; And
And determining whether to perform a load reduction operation on the secondary base station based on the value of the secondary base station load information parameter included in the secondary base station status indication message. The method of claim 1,
The master base station and the secondary base station,
Using a different radio access technology, wherein the master base station is connected to a core network, a control plane and a user plane, and the secondary base station performs only the core network and the user plane connection. The method of claim 1,
Configuring the dual connectivity,
Transmitting, to the secondary base station, an X2 interface setup request message including a full serving cell list of a master base station; And
Receiving an X2 interface setup response message from the secondary base station, the X2 interface setup response message including a complete serving cell list of the secondary base station. The method of claim 1,
The secondary base station load information parameter,
And a value indicating one of overload and a value indicating not overload. The method of claim 4, wherein
Determining whether or not to perform a load reduction operation on the secondary base station,
Determine the start of the load reduction operation for the secondary base station when the secondary base station load information parameter includes a value indicating the overload,
The master base station,
And if the start of the load reduction operation is determined, performing the load reduction operation on the secondary base station until a secondary base station status indication message including a value indicating that it is not the overload is received. In the master base station for managing the secondary base station load,
A controller configured to configure dual connectivity with the secondary base station; And
Includes a receiving unit for receiving a secondary base station status indication message from the secondary base station through the X2 interface,
The control unit,
And determining whether to perform a load reduction operation on the secondary base station based on the value of the secondary base station load information parameter included in the secondary base station status indication message. The method of claim 6,
The master base station and the secondary base station,
A master base station using different radio access technologies, wherein the master base station is connected to a core network, a control plane and a user plane, and the secondary base station performs only the core network and the user plane connection. The method of claim 6,
Further comprising a transmitter for transmitting to the secondary base station an X2 interface setup request message including a full serving cell list of the master base station,
The receiving unit,
And receiving from the secondary base station an X2 interface setup response message including an entire serving cell list of the secondary base station. The method of claim 6,
The secondary base station load information parameter,
And a value indicating any one of an overload value and a non-overload value. The method of claim 9,
The control unit,
Determine the start of the load reduction operation for the secondary base station when the secondary base station load information parameter includes a value indicating the overload,
And if the start of the load reduction operation is determined, performing a load reduction operation on the secondary base station until a secondary base station status indication message including a value indicating that it is not the overload is received. In the central unit (Central Unit) to manage the load of the distributed unit (Distributed Unit),
Receiving a distribution unit status indication message from the distribution unit via the F1 interface; And
And determining whether to perform a load reduction operation on the distributed unit based on a value of the distributed unit load information parameter included in the distributed unit status indication message. The method of claim 11,
The base station is
One central unit and one or more dispersion units,
The central unit is a logical node hosting Radio Resource Control (RRC), Packet Data Convergence Protocol (PDCP) of the base station, and the distributed unit is a Radio Link Control (RLC), Medium Access Control (MAC) and PHY of the base station. (Physical) A method characterized by being a logical node hosting a layer. The method of claim 11,
The distribution unit status indication message,
Message type parameter, transaction identification parameter, and the distributed unit load information parameter. The method of claim 11,
The distributed unit load information parameter is
And a value indicating one of overload and a value indicating not overload. The method of claim 14,
Determining whether or not to perform a load reduction operation for the distribution unit,
Determine the start of the load reduction operation for the distribution unit when the distribution unit load information parameter includes a value indicating the overload,
The central unit,
And if the start of the load reduction operation is determined, perform a load reduction operation on the distribution unit until a distribution unit base station status indication message including a value indicating that it is not the overload is received. In the central unit that manages the load of the distributed unit,
A receiving unit which receives a distribution unit status indication message from the distribution unit through the F1 interface; And
And a controller configured to determine whether to perform a load reduction operation on the distributed unit based on a value of the distributed unit load information parameter included in the distributed unit status indication message. The method of claim 16,
The base station is
One central unit and one or more dispersion units,
The central unit is a logical node hosting Radio Resource Control (RRC), Packet Data Convergence Protocol (PDCP) of the base station, and the distributed unit is a Radio Link Control (RLC), Medium Access Control (MAC) and PHY of the base station. (Physical) Central unit characterized in that the logical node hosting the layer. The method of claim 16,
The distribution unit status indication message,
And a message type parameter, a transaction identification parameter, and the distributed unit load information parameter. The method of claim 16,
The distributed unit load information parameter is
And a central unit including any one of a value indicating an overload and a value indicating no overload. The method of claim 19,
The control unit,
Determine the start of the load reduction operation for the distribution unit when the distribution unit load information parameter includes a value indicating the overload,
And if the start of the load reduction operation is determined, perform a load reduction operation on the distribution unit until a distribution unit base station status indication message including a value indicating that it is not the overload is received.

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