KR20210125854A - Method and apparatus for performing handover from nr to en-dc in next generation mobile communication system - Google Patents

Abstract

The present disclosure relates to a communication technique for converging a 5G communication system to support a higher data rate than a 4G system with IoT technology, and a system thereof. The present disclosure can be applied to intelligent services (for example, smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail business, security- and safety-related services, etc.) based on 5G communication technology and IoT-related technology. The present disclosure discloses a method and apparatus for performing handover in a next generation mobile communication system. A control signal processing method in a wireless communication system includes the steps of: receiving a first control signal transmitted from a base station; processing the received first control signal; and transmitting a second control signal generated based on the processing, to the base station.

Description

METHOD AND APPARATUS FOR PERFORMING HANDOVER FROM NR TO EN-DC IN NEXT GENERATION MOBILE COMMUNICATION SYSTEM

The present disclosure relates to operation of a terminal and a base station in a mobile communication system, and more particularly, to a method and apparatus for performing handover.

Efforts are being made to develop an improved 5G communication system or pre-5G communication system in order to meet the increasing demand for wireless data traffic after the commercialization of the 4G communication system. For this reason, the 5G communication system or the pre-5G communication system is called a 4G network after (Beyond 4G Network) communication system or an LTE system after (Post LTE) system.

In order to achieve a high data rate, the 5G communication system is being considered for implementation in a very high frequency (mmWave) band (eg, such as a 60 gigabyte (60 GHz) band). In order to mitigate the path loss of radio waves and increase the propagation distance of radio waves in the ultra-high frequency band, in the 5G communication system, beamforming, massive MIMO, and Full Dimensional MIMO (FD-MIMO) are used. ), array antenna, analog beam-forming, and large scale antenna technologies are being discussed.

In addition, for network improvement of the system, in the 5G communication system, an evolved small cell, an advanced small cell, a cloud radio access network (cloud RAN), and an ultra-dense network (ultra-dense network) , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation Technology development is underway.

In addition, in the 5G system, FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), which are advanced coding modulation (ACM) methods, and FBMC (Filter Bank Multi Carrier), which are advanced access technologies, NOMA (non orthogonal multiple access), and sparse code multiple access (SCMA) are being developed.

On the other hand, the Internet is evolving from a human-centered connection network where humans create and consume information to an Internet of Things (IoT) network that exchanges and processes information between distributed components such as objects. Internet of Everything (IoE) technology, which combines big data processing technology through connection with cloud servers, etc. with IoT technology, is also emerging. In order to implement IoT, technology elements such as sensing technology, wired and wireless communication and network infrastructure, service interface technology, and security technology are required. , M2M), and MTC (Machine Type Communication) are being studied. In the IoT environment, an intelligent IT (Internet Technology) service that collects and analyzes data generated from connected objects and creates new values in human life can be provided. IoT is a field of smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart home appliance, advanced medical service, etc. can be applied to

Accordingly, various attempts are being made to apply the 5G communication system to the IoT network. For example, in technologies such as sensor network, machine to machine (M2M), and machine type communication (MTC), 5G communication technology is implemented by techniques such as beam forming, MIMO, and array antenna. there will be The application of a cloud radio access network (cloud RAN) as the big data processing technology described above is an example of the convergence of 5G technology and IoT technology.

The 5G communication system is developing to provide various services, and as various services are provided, a method for efficiently providing these services is required. Accordingly, research on a method for performing a handover to enhance the user's communication convenience and quality is being actively conducted.

The present disclosure describes an embodiment for performing handover in a next-generation mobile communication system. In particular, a method of performing handover from a New Radio (NR) communication network to an E-UTRAN NR Dual Connectivity (EN-DC) communication network will be described.

The present disclosure for solving the above problems provides a control signal processing method in a wireless communication system, the method comprising: receiving a first control signal transmitted from a base station; processing the received first control signal; and transmitting a second control signal generated based on the processing to the base station.

According to the disclosed embodiment, radio resources can be efficiently used, and various services can be efficiently provided to a user according to a change in the user's environment.

1A is a diagram illustrating the structure of an LTE system referred to for the description of the present disclosure.
1B is a diagram illustrating a radio protocol structure in an LTE system referred to for the description of the present disclosure.
1C is a diagram illustrating a structure of a next-generation mobile communication system to which the present disclosure is applied.
1D is a diagram illustrating a radio protocol structure of a next-generation mobile communication system to which the present disclosure can be applied.
FIG. 1E is a diagram illustrating an entire flowchart of a case in which an EN-DC handover procedure in NR is performed through one RRC message as an embodiment applied to the present disclosure.
1fa, 1fb, 1fc, and 1fd are diagrams summarizing an existing UE operation when an EN-DC handover procedure in NR is performed through one RRC message as an embodiment applied to the present disclosure.
1ga, 1gb, 1gc, and 1gd are diagrams summarizing the proposed UE operation when the EN-DC handover procedure in NR is performed through one RRC message as an embodiment applied to the present disclosure.
1ha, 1hb, 1hc, and 1hd are diagrams summarizing the proposed UE operation when the EN-DC handover procedure in NR is performed through one RRC message as an embodiment applied to the present disclosure.
1ia and 1ib are diagrams illustrating a proposed UE operation when an EN-DC handover procedure in NR is performed through one RRC message as an embodiment applied to the present disclosure.
1J is a block diagram illustrating an internal structure of a terminal to which the present disclosure is applied.
1K is a block diagram illustrating the configuration of a base station according to the present disclosure.
11 is a diagram summarizing the operation of a proposed terminal when an EN-DC handover procedure is performed in NR through conditional handover.

Hereinafter, the operating principle of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description of the present disclosure, if it is determined that a detailed description of a related well-known function or configuration may unnecessarily obscure the subject matter of the present disclosure, the detailed description thereof will be omitted. In addition, the terms described below are terms defined in consideration of functions in the present disclosure, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification. A term for identifying an access node used in the following description, a term referring to network entities, a term referring to messages, a term referring to an interface between network objects, and a term referring to various identification information and the like are exemplified for convenience of description. Accordingly, the present disclosure is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used.

For convenience of description, the present disclosure uses terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) standard. However, the present disclosure is not limited by the above terms and names, and may be equally applied to systems conforming to other standards.

1A is a diagram illustrating the structure of an LTE system referred to for the description of the present disclosure.

Referring to FIG. 1A, as shown, the radio access network of the LTE system includes a next-generation base station (Evolved Node B, hereinafter eNB, Node B or base station) (1a-05, 1a-10, 1a-15, 1a-20) and It consists of a Mobility Management Entity (MME, 1a-25) and a Serving-Gateway (S-GW, 1a-30). A user equipment (User Equipment, hereinafter, UE or terminal) 1a-35 accesses an external network through the eNBs 1a-05 to 1a-20 and the S-GW 1a-30.

In FIG. 1A , eNBs 1a-05 to 1a-20 correspond to an existing Node B of a UMTS (Universal Mobile Telecommunication System) system. The eNB is connected to the UE (1a-35) through a radio channel and performs a more complex role than the existing Node B. In the LTE system, all user traffic, including real-time services such as VoIP (Voice over IP) through the Internet protocol, are serviced through a shared channel, so the state information such as buffer status of UEs, available transmission power status, and channel status A device for scheduling is required, and the eNBs 1a-05 to 1a-20 are responsible for this. One eNB typically controls multiple cells. For example, in order to implement a transmission rate of 100 Mbps, the LTE system uses, for example, orthogonal frequency division multiplexing (OFDM) in a 20 MHz bandwidth as a radio access technology. In addition, an Adaptive Modulation & Coding (AMC) scheme that determines a modulation scheme and a channel coding rate according to the channel state of the terminal is applied. The S-GW (1a-30) is a device that provides a data bearer, and creates or removes a data bearer under the control of the MME (1a-25). The MME is a device responsible for various control functions as well as the mobility management function for the UE, and is connected to a number of base stations.

1B is a diagram illustrating a radio protocol structure in an LTE system referred to for the description of the present disclosure.

Referring to Figure 1b, the radio protocol of the LTE system is PDCP (Packet Data Convergence Protocol 1b-05, 1b-40), RLC (Radio Link Control 1b-10, 1b-35), MAC (Medium Access) in the UE and the eNB, respectively. Control 1b-15, 1b-30). The PDCPs 1b-05 and 1b-40 are in charge of IP header compression/restore operations. The main functions of PDCP are summarized below.

- Header compression and decompression (ROHC only)

- Transfer of user data

- In-sequence delivery of upper layer PDUs at PDCP re-establishment procedure for RLC AM (Acknowledged Mode)

- Reordering function (For split bearers in DC (only support for RLC AM): PDCP PDU routing for transmission and PDCP PDU reordering for reception)

- Duplicate detection of lower layer SDUs at PDCP re-establishment procedure for RLC AM

- Retransmission of PDCP Service Data Unit (SDU)s at handover and, for split bearers in DC, of PDCP PDUs at PDCP data-recovery procedure, for RLC AM)

- Ciphering and deciphering

- Timer-based SDU discard in uplink.

The radio link control (Radio Link Control, hereinafter referred to as RLC) 1b-10, 1b-35 reconfigures a PDCP protocol data unit (PDU) to an appropriate size to perform an automatic repeat request (ARQ) operation and the like. The main functions of RLC are summarized below.

- Data transfer function (Transfer of upper layer PDUs)

- ARQ function (Error Correction through ARQ (only for AM data transfer))

- Concatenation, segmentation and reassembly of RLC SDUs (only for UM(Unacknowledged Mode) and AM data transfer)

- Re-segmentation of RLC data PDUs (only for AM data transfer)

- Reordering of RLC data PDUs (only for UM and AM data transfer)

- Duplicate detection (only for UM and AM data transfer)

- Protocol error detection (only for AM data transfer)

- RLC SDU discard function (RLC SDU discard (only for UM and AM data transfer))

- RLC re-establishment function

The MACs 1b-15 and 1b-30 are connected to several RLC layer devices configured in one terminal, and perform operations of multiplexing RLC PDUs into MAC PDUs and demultiplexing RLC PDUs from MAC PDUs. The main functions of MAC are summarized below.

- Mapping between logical channels and transport channels

- Multiplexing/demultiplexing of MAC SDUs belonging to one or different logical channels into/from transport blocks (TB) delivered to/from the physical layer on transport channels

- Scheduling information reporting function

- HARQ function (Error correction through HARQ)

- Priority handling between logical channels of one UE

- Priority handling between UEs by means of dynamic scheduling

- MBMS (Multimedia Broadcast Multicast Services) service identification function (MBMS service identification)

- Transport format selection

- Padding function (Padding)

The physical layer (1b-20, 1b-25) channel-codes and modulates upper layer data, creates OFDM symbols and transmits them over a radio channel, or demodulates and channel-decodes OFDM symbols received through the radio channel and transmits them to higher layers do the action In addition, the physical layer uses Hybrid ARQ (HARQ) for additional error correction, and the receiving end transmits whether a packet transmitted from the transmitting end is received with 1 bit. This is called HARQ ACK/NACK information. Downlink HARQ ACK/NACK information for uplink transmission is transmitted through a Physical Hybrid-ARQ Indicator Channel (PHICH) physical channel, and uplink HARQ ACK/NACK information for downlink transmission is PUCCH (Physical Uplink Control Channel) or It may be transmitted through a Physical Uplink Shared Channel (PUSCH) physical channel.

Meanwhile, the PHY layer may consist of one or a plurality of frequencies/carriers, and a technique for simultaneously setting and using a plurality of frequencies is called carrier aggregation (hereinafter, referred to as CA). CA technology refers to the use of only one carrier for communication between the UE (or User Equipment, UE) and the base station (E-UTRAN NodeB, eNB). It is possible to dramatically increase the transmission amount by the number of Meanwhile, in LTE, a cell in a base station using a primary carrier is called a PCell (Primary Cell), and a secondary carrier is called a SCell (Secondary Cell).

Although not shown in this figure, an RRC (Radio Resource Control, hereinafter referred to as RRC) layer exists above the PDCP layer of the terminal and the base station, and the RRC layer provides access and measurement related configuration control messages for radio resource control. can give and receive

1C is a diagram illustrating a structure of a next-generation mobile communication system to which the present disclosure is applied.

Referring to FIG. 1C, as shown, the radio access network of the next-generation mobile communication system includes a next-generation base station (New Radio Node B, hereinafter NR NB, 1c-10) and a New Radio Core Network (NR CN, or NG CN: Next Generation). Core Network, 1c-05). A user terminal (New Radio User Equipment, hereinafter NR UE or terminal, 1c-15) accesses an external network through NR NB 1c-10 and NR CN 1c-05.

In FIG. 1c , NR NBs 1c-10 correspond to an Evolved Node B (eNB) of an existing LTE system. The NR NB is connected to the NR UE 1c-15 through a radio channel and can provide a service superior to that of the existing Node B. In the next-generation mobile communication system, since all user traffic is serviced through a shared channel, a device for scheduling by collecting status information such as buffer status, available transmission power status, and channel status of UEs is required. (1c-10) is in charge. One NR NB typically controls multiple cells. In order to implement ultra-high-speed data transmission compared to the existing LTE, it can have more than the existing maximum bandwidth, and additionally beamforming technology can be grafted by using Orthogonal Frequency Division Multiplexing (hereinafter referred to as OFDM) as a radio access technology. . In addition, an Adaptive Modulation & Coding (AMC) scheme that determines a modulation scheme and a channel coding rate according to the channel state of the terminal is applied. The NR CN 1c-05 performs functions such as mobility support, bearer setup, and quality of service (QoS) setup. The NR CN is a device in charge of various control functions as well as a mobility management function for the terminal and is connected to a plurality of base stations. In addition, the next-generation mobile communication system can be linked with the existing LTE system, and the NR CN is connected to the MME (1c-25) through a network interface. The MME is connected to the existing base station eNB (1c-30).

1D is a diagram illustrating a radio protocol structure of a next-generation mobile communication system to which the present disclosure can be applied.

Referring to Figure 1d, the radio protocol of the next-generation mobile communication system is NR SDAP (Service Data Adaptation Protocol) (1d-01, 1d-45) (1d-01, 1d-45), NR PDCP (1d-05, 1d-40), respectively, in the terminal and the NR base station. It consists of NR RLC(1d-10, 1d-35) and NR MAC(1d-15, 1d-30).

The main functions of the NR SDAPs 1d-01 and 1d-45 may include some of the following functions.

- transfer of user plane data

- Mapping between a QoS flow and a Data Radio Bearer (DRB) for both DL and UL for uplink and downlink

- Marking QoS flow ID in both DL and UL packets for uplink and downlink

- A function of mapping a reflective QoS flow to a data bearer for uplink SDAP PDUs (reflective QoS flow to DRB mapping for the UL SDAP PDUs).

With respect to the SDAP layer device, the UE can receive a configuration of whether to use the header of the SDAP layer device or the function of the SDAP layer device for each PDCP layer device, for each bearer, or for each logical channel with an RRC message, and the SDAP header If is set, the terminal uses the uplink and downlink QoS flow and It may indicate to update or reconfigure mapping information for a data bearer. The SDAP header may include QoS flow ID information indicating QoS. The QoS information may be used as data processing priority and scheduling information to support a smooth service.

The main function of NR PDCP (1d-05, 1d-40) may include some of the following functions.

- Header compression and decompression (ROHC only)

- Transfer of user data

- In-sequence delivery of upper layer PDUs

- Out-of-sequence delivery of upper layer PDUs

- Reordering function (PDCP PDU reordering for reception)

- Duplicate detection of lower layer SDUs

- Retransmission of PDCP SDUs

- Ciphering and deciphering

- Timer-based SDU discard in uplink.

In the above, the reordering function of the NR PDCP device refers to a function of reordering PDCP PDUs received from a lower layer in order based on a PDCP sequence number (SN), and a function of delivering data to a higher layer in the reordered order. may include, or may include a function of directly delivering without considering the order, may include a function of reordering the order to record the lost PDCP PDUs, and report the status of the lost PDCP PDUs It may include a function for the transmitting side, and may include a function for requesting retransmission for lost PDCP PDUs.

The main function of the NR RLC (1d-10, 1d-35) may include some of the following functions.

- Data transfer function (Transfer of upper layer PDUs)

- In-sequence delivery of upper layer PDUs

- Out-of-sequence delivery of upper layer PDUs

- ARQ function (Error Correction through ARQ)

- Concatenation, segmentation and reassembly of RLC SDUs

- Re-segmentation of RLC data PDUs

- Reordering of RLC data PDUs

- Duplicate detection

- Protocol error detection

- RLC SDU discard function (RLC SDU discard)

- RLC re-establishment function

In the above description, the in-sequence delivery function of the NR RLC device refers to a function of sequentially delivering RLC SDUs received from a lower layer to an upper layer, and an original RLC SDU is divided into several RLC SDUs and received. , it may include a function of reassembling it and delivering it, and may include a function of rearranging the received RLC PDUs based on an RLC sequence number (SN) or PDCP SN (sequence number), and rearranging the order It may include a function of recording the lost RLC PDUs, a function of reporting a status on the lost RLC PDUs to the transmitting side, and a function of requesting retransmission of the lost RLC PDUs. and, if there is a lost RLC SDU, it may include a function of sequentially delivering only RLC SDUs before the lost RLC SDU to the upper layer, or if a predetermined timer expires even if there is a lost RLC SDU It may include a function of sequentially delivering all RLC SDUs received before the start of RLC to the upper layer, or if a predetermined timer expires even if there are lost RLC SDUs, all RLC SDUs received so far are sequentially transferred to the upper layer. It may include a function to transmit. In addition, the RLC PDUs may be processed in the order in which they are received (in the order of arrival regardless of the sequence number and sequence number) and delivered to the PDCP device out of sequence (out-of sequence delivery). Segments stored in the buffer or to be received later are received, reconstructed into one complete RLC PDU, processed and delivered to the PDCP device. The NR RLC layer may not include a concatenation function, and the function may be performed in the NR MAC layer or replaced with a multiplexing function of the NR MAC layer.

In the above, the out-of-sequence delivery function of the NR RLC device refers to a function of directly delivering RLC SDUs received from a lower layer to a higher layer regardless of order, and one RLC SDU originally has several RLCs. When received after being divided into SDUs, it may include a function of reassembling and delivering it, and may include a function of storing the RLC SN or PDCP SN of the received RLC PDUs, arranging the order, and recording the lost RLC PDUs. can

The NR MACs 1d-15 and 1d-30 may be connected to several NR RLC layer devices configured in one UE, and the main function of the NR MAC may include some of the following functions.

- Mapping between logical channels and transport channels

- Multiplexing/demultiplexing of MAC SDUs

- Scheduling information reporting function

- HARQ function (Error correction through HARQ)

- Priority handling between logical channels of one UE

- Priority handling between UEs by means of dynamic scheduling

- MBMS service identification

- Transport format selection

- Padding function (Padding)

The NR PHY layer (1d-20, 1d-25) channel-codes and modulates the upper layer data, creates an OFDM symbol and transmits it to the radio channel, or demodulates and channel-decodes the OFDM symbol received through the radio channel to the upper layer. You can perform a forwarding action.

FIG. 1E is a diagram illustrating an overall flowchart of a case in which an EN-DC handover procedure in NR is performed through one RRC message as an embodiment applied to the present disclosure.

In this disclosure, in particular, when EN-DC (E-UTRAN NR Dual connectivity) handover occurs in NR, it is assumed that the change of the Master Node (MN) and the change of the Secondary Node (SN) are simultaneously indicated and occur. , describes the overall terminal operation in which handover can be performed without problems in this situation. Specifically, when EN-DC handover occurs in NR, MN may mean an LTE base station and SN may mean an NR base station. Changing the SN may mean one of adding or changing the SN or changing the configuration information of the SN. In the present disclosure, it may be characterized in that random access to the MN and random access to the changed SN are sequentially performed. That is, after successfully completing the random access to the MN (random access to the PCell), a specific terminal operation to perform random access to the SN (random access to the Primary Cell Group (PSCell)) We would like to suggest the order of 1E is a diagram summarizing the entire flowchart in the above situation, and can be directly applied to an embodiment of the present disclosure. In addition, in FIG. 1E , it may be connected to a 4G core network (meaning EN-DC) or may be connected to a 5G core network (NG-EN-DC). In the present disclosure, for convenience of description, EN-DC and NG-EN-DC will be collectively referred to as EN-DC.

Referring to FIG. 1E , the RRC connected mode terminal 1e-01 may be connected to the PCell cell 1e-02 of the source MN and be in the RRC connected mode (RRC_CONNECTED) (1e-10). The PCell of the source MN may mean an NR cell.

In step 1e-15, the UE may transmit a UECapabilityInformation message to the PCell of the source MN. The message may include at least one of the following.

- Indicator whether nr-HO-ToEN-DC is supported

- Indicate whether nr-HO-ToEN-DC is supported by EN-DC BC

In step 1e-20, handover may be triggered according to a predetermined reason. For example, the predetermined reason is that the UE reports a measurement value to the PCell 1e-02 of the source MN according to the measurement configuration information set by the PCell 1e-02 of the source MN to the UE 1e-01. , it is possible to trigger a handover to a situation in which the neighboring cell is higher than a specific threshold value than the current serving cell based on the measurement value received from the terminal. In step 1e-20, a handover request message is transmitted to the cell 1e-05 of the target MN to be handed over from the PCell cell 1e-02 of the source MN that has made the handover decision. The cell 1e-05 of the target MN in this name may mean an LTE cell.

When the handover request is made in step 1e-20, the SN change procedure (Secondary Cell Group (SCG) addition/ SCG configuration information change/ SCG change) may be performed, and in this case, in the source SN (1e-03) This may be a request to simultaneously process a change to another target SN 1e-04 when performing a handover, which may be included in the handover request message.

Upon receiving the handover request, the target MN 1e-05 transmits an SN addition request message to the target SN 1e-04 in step 1e-25, and in step 1e-30 in the target SN 1e-04 Sends a response message to this. Target SN in the present disclosure may mean NR SN.

In response to the handover in step 1e-35, the target MN 1e-05 may transmit a handover request confirmation message to the source MN 1e-02.

The source MN 1e-02, which has confirmed that handover can be performed through the above series of procedures, may transmit a MobilityFromNRCommand message to the UE in steps 1e-40. The message may include the following information.

- targetRAT-MessageContainer (including LTE RRCConnectionReconfiguration message)

** LTE RRCConnectionReconfiguration message = mobilityControlInfo + nr-SecondaryCellGroupConfig (including reconfigurationWithySync)

** nr-SecondaryCellGroupConfig = NR RRCReconfiguration message

** NR RRCReconfiguration message = sk-Counter-r15, nr-RadioBearerConfig (1 and/or 2), nr-Config

That is, the MobilityFromNRCommand message may include settings for a newly set Master cell group and a secondary cell group, and the settings include mobilityControlInfo and reconfiguratoinWithSync fields that contain parameters necessary for synchronization and handover operation required as handover is performed. can The information set in the mobilityControlInfo field may include serving cell configuration information for the PCell, an RNTI, a T304 timer, and the like, and may include RACH resource information for performing random access. The information set in the reconfiguratoinWithSync field may include serving cell configuration information for the PSCell, RNTI (Radio Network Temporary Identifier), timer information, and the like, and may include RACH resource information for performing random access.

In step 1e-45, the terminal 1e-01 may perform random access to the target MN 1e-05. When the terminal 1e-01 transmits an LTE RRCConnectionReconfigurationComplete message to lower layer devices of the MN by applying the new configuration information received in step 1e-40, random access to the target MN may be triggered. That is, upon receiving LTE RRCConnectionReconfigurationComplete from the MN's MAC, random access to the target MN can be triggered. For reference, scg-reponseNR (ie, NR RRCReconfigurationComplete message) must be accommodated in the LTE RRCConnectionReconfigurationComplete message.

In step 1e-50, the terminal 1e-01 transmits an RRCReconfigurationComplete message to the target MN, and notifies that the handover procedure has been completed.

In step 1e-55, the terminal 1e-01 performs a random access procedure for the target SN. Steps 1e-55 may be performed before steps 1e-50.

In the prior art, the UE performing NR to EN-DC HO first performs random access to the target SN and then performs random access to the target MN. In this case, if random access to the target SN fails, SCG failure may occur, which may cause random access to the target MN to fail. As a UE implementation, random access to the target MN may be performed first and then an SCG failure operation may be performed, but this may put a strain on UE implementation. Therefore, the UE according to the present disclosure proposes to perform random access to the target SN after successfully performing random access to the target MN. The existing terminal operation and the proposed specific terminal operation will be respectively described in the following embodiments.

In step 1e-60, the target MN receives an SN Reconfiguration Complete message indicating that the reconfiguration is complete to the target SN based on the response that the handover and SN change to the target SN are completed through the RRCReconfugrationComplete message received from the terminal in step 1e-50. to convey

1fa, 1fb, 1fc, and 1fd are diagrams summarizing the operation of an existing UE when an EN-DC handover procedure in NR is performed through one RRC message as an embodiment applied to the present disclosure.

1fa, 1fb, 1fc, and 1fd, the UE may establish an RRC connection with an LTE base station or an NR base station to transmit a UECapabilityInformation message to the corresponding base station (1f-05). The message may include at least one of the following.

- Indicator whether nr-HO-ToEN-DC is supported

- Indicate whether nr-HO-ToEN-DC is supported by EN-DC BC

In step 1f-10, the terminal may receive an RRC message including the SecondaryCellGroup from the base station. The RRC message may mean one of RRCConnectionReconfiguration, RRCReconfiguration, and MobilityFromNRCommand messages.

In step 1f-15, the UE may determine whether information indicating LTE HO is included in the RRC message received in step 1f-10. As an example, information indicating LTE HO may mean a mobilityControlInfo field.

In step 1f-15, when the RRC message received in step 1f-10 does not include information indicating LTE HO, the terminal adds a secondary cell group (SCG) or changes the SCG or SCG configuration information. can be changed

In step 1f-20, when the sk-Counter is included in the received RRC message, the terminal may perform a key update procedure. Key update procedure can be performed according to clause 5.3.5.7 of TS 38.331.

If nr-SeconaryCellGroupConfig is included in the received RRC message in step 1f-25, the UE may perform cell group configuration for SCG. The UE may perform cell group configuration for SCG according to clause 5.3.5.3 of TS 38.331. Specifically, the operation related to ReconfigurationWithSync (clause 5.3.5.5.2 of TS 38.331) is performed in steps 1f-26 and 1f-30, and cell group configuration operations for the remaining SCG are performed in steps 1g-f26 and 1f-30. It may mean to perform after step 1f-35 before step 1f-35.

In step 1f-26, the terminal may drive a timer with a timer setting value included in reconfigurationWithySync included in the received RRC message. The corresponding timer may mean a timer for a PScell (Special Cell, SpCell). As an example of the corresponding timer, there may be T304 and the like.

In step 1f-30, the UE may synchronize the downlink of the PScell.

In step 1f-35, when nr-RadioBearerConfig1 is included in the received RRC message, the terminal may perform radio bearer configuration. The UE may perform radio bearer configuration according to clause 5.3.5.6 of TS 38.331.

In step 1f-40, when nr-RadioBearerConfig2 is included in the received RRC message, the terminal may perform radio bearer configuration. The UE may perform radio bearer configuration according to clause 5.3.5.6 of TS 38.331.

In step 1f-45, the terminal may generate an NR RRCReconfigurationComplete message, store it in the LTE RRCConnectionReconfigurationComplete message, and submit it through the E-UTRA MCG.

In step 1f-50, the UE may perform random access to the PSCell.

When the UE successfully performs random access to the PSCell in step 1f-55, the UE may stop the timer for the PSCell.

In step 1f-56, the UE may include the NR RRCReconfigurationComplete message, scg-ConfigResponseNR, in the LTE RRCConnectionReconfigurationComplete message. Steps 1f-56 may occur in steps 1f-45.

In step 1f-57, the terminal may transmit the LTE RRCConnectionReconfigurationComplete message to lower layer devices using the new configuration information.

For reference, steps 1f-50 and 1f-55 may occur after steps 1f-57.

In step 1f-15, when the RRC message received in step 1f-10 includes information indicating LTE HO, the UE may determine that EN-DC HO should be performed in NR. In this case, the RRC message received in step 1f-10 may be a MobilityFromNRCommand message. For reference, the procedure described above can be equally applied to LTE HO with PSCell change. In this case, the received RRC message received in step 1f-10 may be an LTE RRCReconfiguration message.

In step 1f-60, the terminal may drive a timer for the target PCell using a timer set value included in MobilityControlInfo.

In step 1f-65, the terminal may synchronize the downlink of the target PCell.

In step 1f-70, when the sk-Counter is included in the received RRC message, the terminal may perform a key update procedure. Key update procedure can be performed according to clause 5.3.5.7 of TS 38.331.

If nr-SeconaryCellGroupConfig is included in the received RRC message in step 1f-75, the UE may perform cell group configuration for SCG. The UE may perform cell group configuration for SCG according to clause 5.3.5.3 of TS 38.331. Specifically, the operation related to ReconfigurationWithSync (clause 5.3.5.5.2 of TS 38.331) is performed in steps 1f-80 and 1f-85, and the cell group configuration operations for the remaining SCG are steps 1f-80 and 1f-85. After the step is over, it can mean performing before step 1f-90.

In step 1f-80, the terminal may drive a timer with a timer setting value included in reconfigurationWithySync contained in the received RRC message. The corresponding timer may mean a timer for the target PScell. As an example of the corresponding timer, there may be T304 and the like.

In step 1f-85, the UE may synchronize the downlink of the target PScell.

In step 1f-90, when nr-RadioBearerConfig1 is included in the received RRC message, the terminal may perform radio bearer configuration. The UE may perform radio bearer configuration according to clause 5.3.5.6 of TS 38.331.

In step 1f-95, when nr-RadioBearerConfig2 is included in the received RRC message, the terminal may perform radio bearer configuration. The UE may perform radio bearer configuration according to clause 5.3.5.6 of TS 38.331.

In step 1f-100, the UE may generate an NR RRCReconfigurationComplete message, store it in the LTE RRCConnectionReconfigurationComplete message, and submit it through the E-UTRA MCG.

In step 1f-105, the UE may perform random access to the PSCell.

In step 1f-110, when the UE successfully performs random access to the PSCell, it may stop the timer for the PSCell.

In step 1f-115, the UE may include the NR RRCReconfigurationComplete message, scg-ConfigResponseNR, in the LTE RRCConnectionReconfigurationComplete message. Steps 1f-115 may occur in steps 1f-100.

In step 1f-120, the terminal may transmit the LTE RRCConnectionReconfigurationComplete message to lower layer devices using the new configuration information.

In step 1f-125, the UE may initiate random access to the PCell.

In step 1f-130, when the UE successfully performs random access to the PCell, it may stop the timer for the PCell.

1ga, 1gb, 1gc and 1gd are diagrams summarizing the proposed UE operation when the EN-DC handover procedure in NR is performed through one RRC message as an embodiment applied to the present disclosure.

1ga, 1gb, 1gc, and 1gd, the UE may establish an RRC connection with an LTE base station or an NR base station to transmit a UECapabilityInformation message to the corresponding base station (1g-05). The message may include at least one of the following.

- Indicator whether nr-HO-ToEN-DC is supported

- Indicate whether nr-HO-ToEN-DC is supported by EN-DC BC

In step 1g-10, the terminal may receive an RRC message including the SecondaryCellGroup from the base station. The RRC message may mean one of RRCConnectionReconfiguration, RRCReconfiguration, and MobilityFromNRCommand messages.

In step 1g-15, the UE may determine whether information indicating LTE HO is included in the RRC message received in step 1g-10. As an example, information indicating LTE HO may mean a mobilityControlInfo field.

In step 1g-15, when the RRC message received in step 1g-10 does not include information indicating LTE HO, the UE adds a secondary cell group (SCG), or changes the SCG, or sends SCG configuration information. can be changed

In step 1g-20, when the sk-Counter is included in the received RRC message, the terminal may perform a key update procedure. Key update procedure can be performed according to clause 5.3.5.7 of TS 38.331.

In step 1g-25, when the nr-SeconaryCellGroupConfig is included in the received RRC message, the terminal may perform cell group configuration for the SCG. The UE may perform cell group configuration for SCG according to clause 5.3.5.3 of TS 38.331. Specifically, the operation related to ReconfigurationWithSync (clause 5.3.5.5.2 of TS 38.331) is performed in steps 1g-26 and 1g-30, and the cell group configuration operations for the remaining SCG are steps 1g-26 and 1g-30. After the step is over, it may mean performing before step 1g-35.

In step 1g-26, the terminal may drive a timer with a timer setting value included in reconfigurationWithySync contained in the received RRC message. The corresponding timer may mean a timer for a PScell (Special Cell, SpCell). As an example of the corresponding timer, there may be T304 and the like.

In step 1g-30, the UE may synchronize the downlink of the PScell.

In step 1g-35, when nr-RadioBearerConfig1 is included in the received RRC message, the terminal may perform radio bearer configuration. The UE may perform radio bearer configuration according to clause 5.3.5.6 of TS 38.331.

In step 1g-40, when nr-RadioBearerConfig2 is included in the received RRC message, the terminal may perform radio bearer configuration. The UE may perform radio bearer configuration according to clause 5.3.5.6 of TS 38.331.

In step 1g-45, the terminal may generate an NR RRCReconfigurationComplete message, store it in the LTE RRCConnectionReconfigurationComplete message, and submit it through the E-UTRA MCG.

In step 1g-50, the terminal may perform random access to the PSCell.

When the UE successfully performs random access to the PSCell in step 1g-55, it may stop the timer for the PSCell.

In step 1g-56, the UE may include the NR RRCReconfigurationComplete message, scg-ConfigResponseNR, in the LTE RRCConnectionReconfigurationComplete message. Steps 1g-56 may occur in steps 1g-45.

In step 1g-57, the terminal may transmit the LTE RRCConnectionReconfigurationComplete message to lower layer devices using the new configuration information.

For reference, steps 1g-50 and 1g-55 may occur after step 1g-57.

In step 1g-15, when the RRC message received in step 1g-10 includes information indicating LTE HO, the UE may determine that EN-DC HO should be performed in NR. In this case, the RRC message received in step 1g-10 may be a MobilityFromNRCommand message. For reference, the procedure described above can be equally applied to LTE HO with PSCell change. In this case, the received RRC message received in step 1g-10 may be an LTE RRCReconfiguration message.

In step 1g-60, the terminal may drive a timer for the target PCell by using the timer set value included in MobilityControlInfo.

In step 1g-65, the UE may synchronize the downlink of the target PCell.

In step 1g-70, when the sk-Counter is included in the received RRC message, the terminal may perform a key update procedure. Key update procedure can be performed according to clause 5.3.5.7 of TS 38.331.

When nr-SeconaryCellGroupConfig is included in the received RRC message in step 1g-75, the terminal may perform cell group configuration for SCG. The UE may perform cell group configuration for SCG according to clause 5.3.5.3 of TS 38.331. Specifically, the operation related to ReconfigurationWithSync (clause 5.3.5.5.2 of TS 38.331) is performed in steps 1g-80 and 1g-85, and the cell group configuration operations for the remaining SCG are steps 1g-80 and 1g-85. After the step is over, it may mean performing before the 1g-90 step.

In step 1g-80, the terminal may drive a timer with a timer setting value included in reconfigurationWithySync contained in the received RRC message. The corresponding timer may mean a timer for the target PScell. As an example of the corresponding timer, there may be T304 and the like.

In step 1g-85, the UE may synchronize the downlink of the target PScell.

In step 1g-90, when nr-RadioBearerConfig1 is included in the received RRC message, the terminal may perform radio bearer configuration. The UE may perform radio bearer configuration according to clause 5.3.5.6 of TS 38.331.

In step 1g-95, when nr-RadioBearerConfig2 is included in the received RRC message, the terminal may perform radio bearer configuration. The UE may perform radio bearer configuration according to clause 5.3.5.6 of TS 38.331.

In step 1g-100, the terminal may generate an NR RRCReconfigurationComplete message, store it in the LTE RRCConnectionReconfigurationComplete message, and submit it through the E-UTRA MCG.

In step 1g-105, the UE may include the NR RRCReconfigurationComplete message, scg-ConfigResponseNR, in the LTE RRCConnectionReconfigurationComplete message.

In step 1g-110, the terminal may transmit the LTE RRCConnectionReconfigurationComplete message to lower layer devices using the new configuration information.

In step 1g-115, the terminal may perform random access to the PCell.

In step 1g-120, when the UE successfully performs random access to the PCell, the UE may stop the timer for the PCell.

1g-125 The UE may initiate random access to the PSCell. The UE may initiate random access to the PSCell when the random access to the PCell is successfully performed.

In step 1g-130, when the UE successfully performs random access to the PSCell, it may stop the timer for the PCell.

In the present disclosure, since the UE drives the timer for the PSCell unnecessarily quickly (1g-80) before performing random access on the PSCell, there is a disadvantage that the timer for the PSCell may expire.

1ha, 1hb, 1hc, and 1hd are diagrams summarizing the proposed UE operation when the EN-DC handover procedure in NR is performed through one RRC message as an embodiment applied to the present disclosure.

1ha, 1hb, 1hc and 1hd, the UE may establish an RRC connection with an LTE base station or an NR base station to transmit a UECapabilityInformation message to the corresponding base station (1h-05). The message may include at least one of the following.

- Indicator whether nr-HO-ToEN-DC is supported

- Indicate whether nr-HO-ToEN-DC is supported by EN-DC BC

In step 1h-10, the terminal may receive an RRC message including the SecondaryCellGroup from the base station. The RRC message may mean one of RRCConnectionReconfiguration, RRCReconfiguration, and MobilityFromNRCommand messages.

In step 1h-15, the terminal may determine whether information indicating LTE HO is included in the RRC message received in step 1h-10. As an example, information indicating LTE HO may mean a mobilityControlInfo field.

In step 1h-15, when the RRC message received in step 1h-10 does not include information indicating LTE HO, the terminal adds a secondary cell group (SCG) or changes the SCG or SCG configuration information. can be changed

In step 1h-20, when the sk-Counter is included in the received RRC message, the terminal may perform a key update procedure. Key update procedure can be performed according to clause 5.3.5.7 of TS 38.331.

When nr-SeconaryCellGroupConfig is included in the received RRC message in step 1h-25, the UE may perform cell group configuration for SCG. The UE may perform cell group configuration for SCG according to clause 5.3.5.3 of TS 38.331. Specifically, the operation related to ReconfigurationWithSync (clause 5.3.5.5.2 of TS 38.331) is performed in steps 1h-26 and 1h-30, and the cell group configuration operations for the remaining SCG are steps 1h-26 and 1h-30. It may mean performing before steps 1h-35 after the step is over.

In step 1h-26, the terminal may drive a timer with a timer setting value included in reconfigurationWithySync contained in the received RRC message. The corresponding timer may mean a timer for a PScell (Special Cell, SpCell).

In step 1h-30, the UE may synchronize the downlink of the PScell.

In step 1h-35, when nr-RadioBearerConfig1 is included in the received RRC message, the terminal may perform radio bearer configuration. The UE may perform radio bearer configuration according to clause 5.3.5.6 of TS 38.331.

In step 1h-40, when nr-RadioBearerConfig2 is included in the received RRC message, the terminal may perform radio bearer configuration. The UE may perform radio bearer configuration according to clause 5.3.5.6 of TS 38.331.

In step 1h-45, the terminal may generate an NR RRCReconfigurationComplete message, store it in the LTE RRCConnectionReconfigurationComplete message, and submit it through the E-UTRA MCG.

In step 1h-50, the UE may perform random access to the PSCell.

In step 1h-55, when the UE successfully performs random access to the PSCell, it may stop the timer for the PSCell.

In step 1h-56, the UE may include the NR RRCReconfigurationComplete message, scg-ConfigResponseNR, in the LTE RRCConnectionReconfigurationComplete message. Steps 1h-56 may occur in steps 1h-45.

In step 1h-57, the terminal may transmit the LTE RRCConnectionReconfigurationComplete message to lower layer devices using the new configuration information.

For reference, steps 1h-50 and 1h-55 may occur after steps 1h-57.

In step 1h-15, when the RRC message received in step 1h-10 includes information indicating LTE HO, the UE may determine that EN-DC HO should be performed in NR. In this case, the RRC message received in step 1h-10 may be a MobilityFromNRCommand message. For reference, the procedure described above can be equally applied to LTE HO with PSCell change. In this case, the received RRC message received in step 1h-10 may be an LTE RRCReconfiguration message.

In step 1h-60, the terminal may drive a timer for the target PCell by using the timer set value included in MobilityControlInfo.

In step 1h-65, the UE may synchronize the downlink of the target PCell.

In step 1h-70, when the sk-Counter is included in the received RRC message, the terminal may perform a key update procedure. Key update procedure can be performed according to clause 5.3.5.7 of TS 38.331.

In step 1h-75, when the nr-SeconaryCellGroupConfig is included in the received RRC message, the terminal may perform cell group configuration for the SCG. The UE may perform cell group configuration for SCG according to clause 5.3.5.3 of TS 38.331. Specifically, the operation related to ReconfigurationWithSync (clause 5.3.5.5.2 of TS 38.331) is performed in steps 1h-115 and 1h-120, and may mean performing cell group configuration operations for the remaining SCG.

In step 1h-80, when nr-RadioBearerConfig1 is included in the received RRC message, the terminal may perform radio bearer configuration. The UE may perform radio bearer configuration according to clause 5.3.5.6 of TS 38.331.

In step 1h-85, when nr-RadioBearerConfig2 is included in the received RRC message, the terminal may perform radio bearer configuration. The UE may perform radio bearer configuration according to clause 5.3.5.6 of TS 38.331.

In step 1h-90, the terminal may generate an NR RRCReconfigurationComplete message, store it in the LTE RRCConnectionReconfigurationComplete message, and submit it through the E-UTRA MCG.

In step 1h-95, the UE may include the NR RRCReconfigurationComplete message, scg-ConfigResponseNR, in the LTE RRCConnectionReconfigurationComplete message.

In step 1h-100, the terminal may transmit the LTE RRCConnectionReconfigurationComplete message to lower layer devices using the new configuration information.

In step 1h-105, the UE may perform random access to the PCell.

In step 1h-110, when the UE successfully performs random access to the PCell, it may stop the timer for the PCell.

In step 1h-115, the terminal may drive a timer with a timer setting value included in reconfigurationWithySync contained in the received RRC message. The corresponding timer may mean a timer for the target PSCell. As an example of the corresponding timer, there may be T304 and the like.

In step 1h-120, the terminal may synchronize the downlink of the target PScell. For reference, steps 1h-120 may be performed in steps 1h-75.

1h-125 The UE may initiate random access to the PSCell. The UE may initiate random access to the PSCell when the random access to the PCell is successfully performed.

In step 1h-130, when the UE successfully performs random access to the PSCell, it may stop the timer for the PCell.

In the present disclosure, when initiating or initiating random access to the PSCell, a timer for the PSCell is driven.

1ia and 1ib are diagrams summarizing a proposed UE operation when an EN-DC handover procedure in NR is performed through one RRC message as an embodiment applied to the present disclosure.

1ia and 1ib, the terminal may establish an RRC connection with an LTE base station or an NR base station to transmit a UECapabilityInformation message to the corresponding base station (1e-05). The message may include at least one of the following.

- Indicator whether nr-HO-ToEN-DC is supported

- Indicate whether nr-HO-ToEN-DC is supported by EN-DC BC

In step 1i-10, the terminal may receive an RRC message including the SecondaryCellGroup from the base station. The RRC message may mean one of RRCConnectionReconfiguration, RRCReconfiguration, and MobilityFromNRCommand messages.

In step 1i-15, the terminal may determine whether information indicating LTE HO is included in the RRC message received in step 1i-10. As an example, information indicating LTE HO may mean a mobilityControlInfo field.

In step 1i-15, when the RRC message received in step 1i-10 does not include information indicating LTE HO, the terminal adds a secondary cell group (SCG), or changes the SCG or SCG configuration information. can be changed The subsequent operation is the same as in the above-described embodiment.

In step 1i-15, when information indicating LTE HO is included in the RRC message received in step 1i-10, the UE may determine that EN-DC HO should be performed in NR. In this case, the RRC message received in step 1i-10 may be a MobilityFromNRCommand message. For reference, the procedure described above can be equally applied to LTE HO with PSCell change. In this case, the received RRC message received in step 1i-10 may be an LTE RRCReconfiguration message.

In step 1i-20, the terminal may drive a timer for the target PCell by using the timer set value included in MobilityControlInfo.

In step 1i-25, the UE may synchronize the downlink of the target PCell.

In step 1i-30, when the sk-Counter is included in the received RRC message, the terminal may perform a key update procedure. Key update procedure can be performed according to clause 5.3.5.7 of TS 38.331.

In step 1i-35, when nr-RadioBearerConfig1 is included in the received RRC message, the terminal may perform radio bearer configuration. The UE may perform radio bearer configuration according to clause 5.3.5.6 of TS 38.331.

In step 1i-40, when nr-RadioBearerConfig2 is included in the received RRC message, the terminal may perform radio bearer configuration. The UE may perform radio bearer configuration according to clause 5.3.5.6 of TS 38.331.

In step 1i-45, the terminal may transmit the LTE RRCConnectionReconfigurationComplete message to lower layer devices using the new configuration information.

In step 1i-50, the terminal may perform random access to the PCell.

In step 1i-55, when the UE successfully performs random access to the PCell, the UE may stop the timer for the PCell.

In step 1i-60, when the nr-SeconaryCellGroupConfig is included in the received RRC message, the terminal may perform cell group configuration for the SCG. The UE may perform cell group configuration for SCG according to clause 5.3.5.3 of TS 38.331.

In step 1i-65, the terminal may generate an NR RRCReconfigurationComplete message, store it in the LTE RRCConnectionReconfigurationComplete message, and submit it through the E-UTRA MCG. In addition, random access to the PSCell may be initiated. In addition, the UE may include the NR RRCReconfigurationComplete message, scg-ConfigResponseNR, in the LTE RRCConnectionReconfigurationComplete message.

In step 1i-70, the terminal may transmit the LTE RRCConnectionReconfigurationComplete message to lower layer devices using the new configuration information.

In the present disclosure, the UE has a feature of sending the LTE RRCConnectionReconfigurationComplete message twice.

FIG. 11 is a diagram summarizing a proposed UE operation when an EN-DC handover procedure is performed in NR through conditional handover.

Referring to FIG. 11, the UE may establish an RRC connection with an LTE base station or an NR base station to transmit a UECapabilityInformation message to the corresponding base station (11-05). The message may include at least one of the following.

- Conditional handover support from NR to EN-DC indicator (nr-CHO-ToEN-DC indicator)

- Indicate whether conditional handover is supported from NR to EN-DC for each EN-DC BC

In step 11-10, an RRC message including configuration information for performing handover from NR to EN-DC and a conditional handover triggering condition from NR to EN-DC may be received. Unlike the above embodiment, the UE according to the present embodiment does not perform EN-DC handover from NR in step 11-10.

In step 11-15, the UE may determine whether a conditional handover triggering condition is satisfied from NR to EN-DC.

If the conditional handover triggering condition is satisfied from NR to EN-DC in step 11-15, the UE may perform EN-DC handover operation from NR according to the above-described embodiments in step 11-20.

If the conditional handover triggering condition from NR to EN-DC is not satisfied in step 11-15, the UE may not perform an EN-DC handover operation from NR in step 11-25.

In the present specification, an operation performed according to the standard of TS 38.331 is disclosed, but the performance of such operation is not necessarily limited thereto. In the present disclosure, TS 38.331 illustrates one of the RRC (Radio Resource Control) protocols of the control plane can mean that In addition to TS 38.331, it can also be applied to operations on other standards of 3GPP.

1J is a block diagram illustrating an internal structure of a terminal to which the present disclosure is applied.

Referring to the drawings, the terminal includes a radio frequency (RF) processing unit 1j-10, a baseband processing unit 1j-20, a storage unit 1j-30, and a control unit 1j-40. .

The RF processing unit 1j-10 performs a function for transmitting and receiving a signal through a wireless channel, such as band conversion and amplification of the signal. That is, the RF processing unit 1j-10 up-converts the baseband signal provided from the baseband processing unit 1j-20 into an RF band signal, transmits it through an antenna, and receives an RF band signal received through the antenna. down-converts to a baseband signal. For example, the RF processing unit 1j-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital to analog converter (DAC), an analog to digital converter (ADC), etc. can In the figure, only one antenna is shown, but the terminal may include a plurality of antennas. Also, the RF processing unit 1j-10 may include a plurality of RF chains. Furthermore, the RF processing unit 1j-10 may perform beamforming. For the beamforming, the RF processing unit 1j-10 may adjust the phase and magnitude of each of the signals transmitted and received through a plurality of antennas or antenna elements. In addition, the RF processing unit may perform MIMO, and may receive multiple layers when performing MIMO operation.

The baseband processing unit 1j-20 performs a function of converting between a baseband signal and a bit stream according to a physical layer standard of the system. For example, when transmitting data, the baseband processing unit 1j-20 generates complex symbols by encoding and modulating a transmitted bit stream. Also, when receiving data, the baseband processing unit 1j-20 restores a received bit stream by demodulating and decoding the baseband signal provided from the RF processing unit 1j-10. For example, in the case of orthogonal frequency division multiplexing (OFDM), when transmitting data, the baseband processing unit 1j-20 encodes and modulates a transmitted bit stream to generate complex symbols, and convert the complex symbols to subcarriers. After mapping to , OFDM symbols are constructed through inverse fast Fourier transform (IFFT) operation and cyclic prefix (CP) insertion. In addition, when receiving data, the baseband processing unit 1j-20 divides the baseband signal provided from the RF processing unit 1j-10 into OFDM symbol units, and sends them to subcarriers through a fast Fourier transform (FFT) operation. After reconstructing the mapped signals, the received bit stream is reconstructed through demodulation and decoding.

The baseband processing unit 1j-20 and the RF processing unit 1j-10 transmit and receive signals as described above. Accordingly, the baseband processing unit 1j-20 and the RF processing unit 1j-10 may be referred to as a transmitter, a receiver, a transceiver, or a communication unit. Furthermore, at least one of the baseband processing unit 1j-20 and the RF processing unit 1j-10 may include a plurality of communication modules to support a plurality of different radio access technologies. In addition, at least one of the baseband processing unit 1j-20 and the RF processing unit 1j-10 may include different communication modules to process signals of different frequency bands. For example, the different wireless access technologies may include a wireless LAN (eg, IEEE 802.11), a cellular network (eg, LTE), and the like. In addition, the different frequency bands may include a super high frequency (SHF) (eg, 2.NRHz, NRhz) band and a millimeter wave (eg, 60GHz) band.

The storage unit 1j-30 stores data such as a basic program, an application program, and setting information for the operation of the terminal. In particular, the storage unit 1j-30 may store information related to a second access node that performs wireless communication using a second wireless access technology. In addition, the storage unit 1j-30 provides stored data according to the request of the control unit 1j-40.

The controller 1j-40 controls overall operations of the terminal. For example, the control unit 1j-40 transmits and receives signals through the baseband processing unit 1j-20 and the RF processing unit 1j-10. In addition, the control unit 1j-40 writes and reads data in the storage unit 1j-40. To this end, the controller 1j-40 may include at least one processor. For example, the controller 1j-40 may include a communication processor (CP) that controls for communication and an application processor (AP) that controls an upper layer such as an application program.

1K is a block diagram illustrating the configuration of a base station according to the present disclosure.

As shown in the figure, the base station includes an RF processing unit 1k-10, a baseband processing unit 1k-20, a backhaul communication unit 1k-30, a storage unit 1k-40, and a control unit 1k-50. is comprised of

The RF processing unit 1k-10 performs a function for transmitting and receiving a signal through a wireless channel, such as band conversion and amplification of the signal. That is, the RF processor 1k-10 up-converts the baseband signal provided from the baseband processor 1k-20 into an RF band signal, transmits it through an antenna, and receives the RF band signal through the antenna. down-converts to a baseband signal. For example, the RF processing unit 1k-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like. Although only one antenna is shown in the drawing, the first access node may include a plurality of antennas. Also, the RF processing unit 1k-10 may include a plurality of RF chains. Furthermore, the RF processing unit 1k-10 may perform beamforming. For the beamforming, the RF processing unit 1k-10 may adjust the phase and magnitude of each of the signals transmitted and received through a plurality of antennas or antenna elements. The RF processing unit may perform a downlink MIMO operation by transmitting one or more layers.

The baseband processing unit 1k-20 performs a function of converting a baseband signal and a bit stream according to the physical layer standard of the first radio access technology. For example, when transmitting data, the baseband processing unit 1k-20 generates complex symbols by encoding and modulating a transmitted bit stream. Also, upon data reception, the baseband processing unit 1k-20 restores a received bit stream by demodulating and decoding the baseband signal provided from the RF processing unit 1k-10. For example, in the OFDM scheme, when transmitting data, the baseband processing unit 1k-20 generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and then IFFT OFDM symbols are constructed through operation and CP insertion. Also, upon data reception, the baseband processing unit 1k-20 divides the baseband signal provided from the RF processing unit 1k-10 into OFDM symbol units, and restores signals mapped to subcarriers through FFT operation. After that, the received bit stream is restored through demodulation and decoding. The baseband processing unit 1k-20 and the RF processing unit 1k-10 transmit and receive signals as described above. Accordingly, the baseband processing unit 1k-20 and the RF processing unit 1k-10 may be referred to as a transmitter, a receiver, a transceiver, a communication unit, or a wireless communication unit.

The backhaul communication unit 1k-30 provides an interface for communicating with other nodes in the network. That is, the backhaul communication unit 1k-30 converts a bit string transmitted from the main base station to another node, for example, an auxiliary base station, a core network, etc. into a physical signal, and converts the physical signal received from the other node into a bit convert to heat

The storage unit 1k-40 stores data such as a basic program, an application program, and setting information for the operation of the main station. In particular, the storage unit 1k-40 may store information on a bearer assigned to an accessed terminal, a measurement result reported from the accessed terminal, and the like. In addition, the storage unit 1k-40 may store information serving as a criterion for determining whether to provide or stop multiple connections to the terminal. In addition, the storage unit 1k-40 provides stored data according to the request of the control unit 1k-50.

The control unit 1k-50 controls overall operations of the main station. For example, the control unit 1k-50 transmits and receives signals through the baseband processing unit 1k-20 and the RF processing unit 1k-10 or through the backhaul communication unit 1k-30. In addition, the control unit 1k-50 writes and reads data in the storage unit 1k-40. To this end, the control unit 1k-50 may include at least one processor.

Claims (1)

A control signal processing method in a wireless communication system, comprising:
receiving a first control signal transmitted from a base station;
processing the received first control signal; and
and transmitting a second control signal generated based on the processing to the base station.

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