KR20210152940A - Apparatus and method for performing random access based on network slicing - Google Patents

Abstract

The present specification relates to a device and method for performing random access based on network slicing. According to the present specification, the method comprises the following steps of: receiving slicing-related information in which random access resources and parameters related to a priority order of random access are individually set for each network slice, from a base station; and performing a random access procedure for the base station based on the slicing-related information. The effective random access can be performed in a network slicing environment.

Description

Apparatus and method for performing random access based on network slicing {APPARATUS AND METHOD FOR PERFORMING RANDOM ACCESS BASED ON NETWORK SLICING}

The present invention relates to a wireless communication system, and more particularly, to an apparatus and method for performing random access based on network slicing.

3GPP paved the way for commercial application of 5G by completing the first global 5G New Radio (NR) standard in Release (Rel)-15. NR is a radio access technology that provides an improved data rate compared to LTE and can satisfy various QoS requirements required for each segmented and detailed usage scenario. In particular, enhancement Mobile BroadBand (eMBB), massive MTC (mmTC), and Ultra Reliable and Low Latency Communications (URLLC) have been defined as representative usage scenarios of NR. As a method for satisfying the requirements for each scenario, a frame structure that is flexible compared to LTE is provided. In addition, a network slicing technique is being considered. The network slicing technology provides network resources and network functions for each service by creating and providing an end-to-end (E2E) resource spanning the RAN (Radio Access Network) to the core network as an independent slice. ), customization, and independent management and orchestration, a new concept applied to 5G mobile communications that can be applied to the RAN (Radio Access Network) and the core network of mobile communications to be.

Communication technology combines with the development of technologies such as Network Function Virtualization (NFV) and Software Defined Network (SDN) to optimize the network slice for each application in one huge network. ) is developed in a way that constitutes

Network slice creates a logically separated E2E (End-to-End) network, including radio access, transmission, and 5G core equipment, from a terminal through one physical network, and provides various services with different characteristics. It provides a dedicated network specialized for services. That is, the network slice is a technology that provides network resources and network functions necessary for the service requested by the terminal as one independent slice.

An object of the present invention is to provide an apparatus and method for performing random access based on network slicing.

According to an aspect of the present invention, there is provided a method for performing random access of a terminal based on network slicing. The method includes receiving, from a base station, slicing-related information in which random access resources and parameters related to the priority of random access are individually set for each network slice, and a random access procedure for the base station based on the slicing-related information. including the steps of

In one aspect, the slicing-related information may be received by being included in system information or an RRC message.

In another aspect, the random access procedure includes transmitting a random access preamble to the base station based on the random access resource and the priority of the random access, and sending a random access response message to the random access preamble from the base station It may include the step of receiving.

In another aspect, the slicing-related information may individually set a random access transmit power offset value for each slice.

In another aspect, a random access transmit power offset value of a network slice dedicated to an Ultra Reliable and Low Latency Communications (URLLC) service may be greater than a random access transmit power offset value of a network slice that is not dedicated to the URLLC service.

In another aspect, the parameters related to the random access resource include msg1-FDM and msg1-FrequencyStart, and the msg1-FDM and msg1-FrequencyStart may be individually configured for each network slice.

In another aspect, when the terminal performs handover from a serving cell to a target cell, the random access procedure may be performed on a contention-free basis.

In another aspect, the handover related message of the base station may include at least a part of the slicing related information.

In another aspect, the handover related message of the base station may include information on whether or not network slicing is applied.

In another aspect, a random access backoff time of a network slice dedicated to the URLLC service may be smaller than a random access backoff time of another network slice not dedicated to the URLLC service.

In another aspect, the random access backoff time of a network slice dedicated to the mMTC service may be greater than the random access backoff time of another network slice not dedicated to the mMTC service.

According to another aspect of the present invention, there is provided a method for performing random access of a base station based on network slicing. The method includes transmitting, to the terminal, slicing-related information in which random access resources and parameters related to the priority of random access are individually set for each network slice, and performing a random access procedure with the terminal based on the slicing-related information includes steps.

In one aspect, the slicing-related information may be received by being included in system information or an RRC message.

In another aspect, the random access procedure includes receiving a random access preamble from the terminal based on the random access resource and the priority of the random access, and a random access response message to the random access preamble to the terminal It may include the step of transmitting.

In another aspect, the slicing-related information may individually set a random access transmit power offset value for each slice.

In another aspect, a random access transmit power offset value of a network slice dedicated to an Ultra Reliable and Low Latency Communications (URLLC) service may be greater than a random access transmit power offset value of a network slice that is not dedicated to the URLLC service.

In another aspect, the parameters related to the random access resource include msg1-FDM and msg1-FrequencyStart, and the msg1-FDM and msg1-FrequencyStart may be individually configured for each network slice.

In another aspect, when the terminal performs handover from a serving cell to a target cell, the random access procedure may be performed on a contention-free basis.

In another aspect, the handover related message of the base station may include at least a part of the slicing related information.

In another aspect, the handover related message of the base station may include information on whether or not network slicing is applied.

In another aspect, a random access backoff time of a network slice dedicated to the URLLC service may be smaller than a random access backoff time of another network slice not dedicated to the URLLC service.

In another aspect, the random access backoff time of a network slice dedicated to the mMTC service may be greater than the random access backoff time of another network slice not dedicated to the mMTC service.

According to another aspect of the present invention, there is provided a terminal that performs random access based on network slicing. The terminal receives, from the base station, slicing-related information in which random access resources and parameters related to the priority of random access are individually set for each network slice, and performs a random access procedure for the base station based on the slicing-related information. and a processor for generating a random access preamble used in the random access procedure.

According to another aspect of the present invention, there is provided a base station that performs random access based on network slicing. The base station transmits slicing-related information in which random access resources and parameters related to the priority of random access are individually set for each network slice to the terminal, and a transceiver unit for performing a random access procedure with the terminal based on the slicing-related information , and a processor that generates a random access response message used in the random access procedure.

Effective random access can be performed in a network slicing environment.

1 is a conceptual diagram illustrating a wireless communication system according to an embodiment of the present invention.
2 is an exemplary diagram illustrating an NR system to which a data transmission method according to an embodiment of the present invention can be applied.
3 is a diagram for explaining a resource grid supported by a radio access technology to which this embodiment can be applied.
4 is a diagram for explaining a bandwidth part supported by a radio access technology to which the present embodiment can be applied.
5 is a diagram exemplarily illustrating a synchronization signal block in a radio access technology to which the present embodiment can be applied.
6 is a diagram for explaining a random access procedure in a radio access technology to which this embodiment can be applied.
7 is a diagram for explaining a concept of a network slice according to an embodiment.
8 shows a terminal and a network node in which an embodiment of the present invention is implemented.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention. In describing each figure, like reference numerals have been used for like elements.

In this specification, terms such as “first”, “second”, “A”, and “B” may be used to describe various components, but the components should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. The term “and/or” also includes combinations of a plurality of related listed items or any of a plurality of related listed items.

When an element is referred to as being “connected” or “connected” to another element, it is understood that it may be directly connected or connected to the other element, but other elements may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle.

The terminology used herein is used only to describe specific embodiments, and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In this specification, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, component, part, or a combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, terms used herein have the same meanings as commonly understood by those of ordinary skill in the art to which the present invention belongs, including technical or scientific terms. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present specification. does not

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram illustrating a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 1 , a wireless communication system 100 includes a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3. , 130-4, 130-5, 130-6).

Each of the plurality of communication nodes may support at least one communication protocol. For example, each of the plurality of communication nodes is a CDMA (Code Division Multiple Access) based communication protocol, WCDMA (Wideband CDMA) based communication protocol, TDMA (Time Division Multiple Access) based communication protocol, FDMA (Frequency Division Multiple) Access) based communication protocol, OFDM (Orthogonal Frequency Division Multiplexing) based communication protocol, OFDMA (Orthogonal Frequency Division Multiple Access) based communication protocol, SC (Single Carrier)-FDMA based communication protocol, NOMA (Non-Orthogonal Multiplexing) Access)-based communication protocol, space division multiple access (SDMA)-based communication protocol, etc. may be supported.

The wireless communication system 100 includes a plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 and a plurality of user equipments 130-1, 130-2, 130-3, 130-4, 130-5, 130-6).

Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to the coverage of the first base station 110-1. The second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong to the coverage of the second base station 110-2. The fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5, and the sixth terminal 130-6 may belong to the coverage of the third base station 110-3. . The first terminal 130-1 may belong to the coverage of the fourth base station 120-1. The sixth terminal 130-6 may belong to the coverage of the fifth base station 120-2.

Here, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 is a NodeB, an evolved NodeB, and a next generation Node B (NodeB). B, gNB), BTS (Base Transceiver Station), radio base station (radio base station), radio transceiver (radio transceiver), access point (access point), access node (node), roadside unit (road side unit, RSU), DU (Digital Unit), CDU (Cloud Digital Unit), RRH (Radio Remote Head), RU (Radio Unit), TP (Transmission Point), TRP (transmission and reception point), to be referred to as a relay node (relay node), etc. can Each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 is a terminal, an access terminal, a mobile terminal, It may be referred to as a station, a subscriber station, a mobile station, a portable subscriber station, a node, a device, and the like.

A plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6) Each may support cellular communication (eg, long term evolution (LTE), advanced (LTE-A), new radio (NR), etc. defined in the 3rd generation partnership project (3GPP) standard). Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in different frequency bands or may operate in the same frequency band. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to each other through an ideal backhaul or a non-ideal backhaul, and the ideal backhaul Alternatively, information may be exchanged with each other through a non-ideal backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to a core network (not shown) through an ideal backhaul or a non-ideal backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits a signal received from the core network to the corresponding terminals 130-1, 130-2, 130-3, 130 -4, 130-5, 130-6), and a signal received from the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) is transmitted to the core network can be sent to

Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may support OFDMA-based downlink transmission. In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 supports OFDMA or DFT-S-OFDM-based uplink transmission, or SC -FDMA-based uplink transmission may be supported. In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits multiple input multiple output (MIMO) (eg, single user (SU)-MIMO, MU (Multi User)-MIMO, massive MIMO, etc.), Coordinated Multipoint (CoMP) transmission, carrier aggregation transmission, transmission in an unlicensed band, direct device to device, D2D) communication (or Proximity services (ProSe)) may be supported, etc. Here, each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 Base stations 110-1, 110-2, 110-3, 120-1, 120-2 and corresponding operations and/or base stations 110-1, 110-2, 110-3, 120-1, 120-2 ) can perform operations supported by

For example, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 based on the SU-MIMO method, and the fourth terminal 130-4 may transmit a signal based on the SU-MIMO method. A signal may be received from the second base station 110 - 2 . Alternatively, the second base station 110 - 2 may transmit a signal to the fourth terminal 130 - 4 and the fifth terminal 130 - 5 based on the MU-MIMO scheme, and the fourth terminal 130 - 4 . and each of the fifth terminals 130 - 5 may receive a signal from the second base station 110 - 2 by the MU-MIMO method. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may transmit a signal to the fourth terminal 130-4 based on the CoMP scheme, and the fourth The terminal 130-4 may receive signals from the first base station 110-1, the second base station 110-2, and the third base station 110-3 by the CoMP method. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 includes the terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6) and a signal may be transmitted/received based on the CA method.

Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 coordinates D2D communication between the fourth terminal 130-4 and the fifth terminal 130-5. (coordination), each of the fourth terminal 130-4 and the fifth terminal 130-5 is D2D communication by the coordination of each of the second base station 110-2 and the third base station 110-3 can be performed.

Hereinafter, even when a method (eg, transmission or reception of a signal) performed in a first communication node among communication nodes is described, a second communication node corresponding thereto corresponds to the method performed in the first communication node A method (eg, receiving or transmitting a signal) may be performed. That is, when the operation of the terminal is described, the corresponding base station may perform the operation corresponding to the operation of the terminal. Conversely, when the operation of the base station is described, the corresponding terminal may perform the operation corresponding to the operation of the base station.

Also, hereinafter, downlink (DL) means communication from a base station to a terminal, and uplink (UL) means communication from a terminal to a base station. In the downlink, the transmitter may be a part of the base station, and the receiver may be a part of the terminal. In the uplink, the transmitter may be a part of the terminal, and the receiver may be a part of the base station.

Recently, as the spread of smartphones and Internet of Things (IoT) terminals is rapidly spreading, the amount of information exchanged through a communication network is increasing. Accordingly, in the next-generation wireless access technology, an environment (eg, enhanced mobile broadband communication) that provides a faster service to more users than the existing communication system (or the existing radio access technology) )) needs to be considered. To this end, design of a communication system in consideration of MTC (Machine Type Communication) providing a service by connecting a plurality of devices and objects is being discussed. In addition, the design of a communication system (eg, URLLC (Ultra-Reliable and Low Latency Communication) that considers a service and/or terminal sensitive to communication reliability and/or latency) is being discussed.

Hereinafter, in this specification, for convenience of description, the next-generation radio access technology is referred to as a New Radio Access Technology (RAT), and a wireless communication system to which the New RAT is applied is referred to as a New Radio (NR) system. In the present specification, NR-related frequencies, frames, subframes, resources, resource blocks, regions, bands, subbands, control channels, data channels, synchronization signals, various reference signals, various signals, or various messages are past or present. It can be interpreted in various meanings used or used in the future.

2 is an exemplary diagram illustrating an NR system to which a data transmission method according to an embodiment of the present invention can be applied.

NR, a next-generation wireless communication technology that is being standardized in 3GPP, provides an improved data rate compared to LTE and is a radio access technology that can satisfy various QoS requirements required for each segmented and detailed usage scenario. . In particular, enhancement Mobile BroadBand (eMBB), massive MTC (mmTC), and Ultra Reliable and Low Latency Communications (URLLC) have been defined as representative usage scenarios of NR. As a method for satisfying the requirements for each scenario, a frame structure that is flexible compared to LTE is provided. The frame structure of NR supports a frame structure based on multiple subcarriers. The basic subcarrier spacing (SubCarrier Spacing, SCS) becomes 15 kHz, and a total of 5 types of SCS are supported at 15 kHz*2^n.

Referring to Figure 2, the NG-RAN (Next Generation-Radio Access Network) is a control plane (RRC) protocol termination for the NG-RAN user plane (SDAP / PDCP / RLC / MAC / PHY) and UE (User Equipment) It is composed of gNBs that provide Here, NG-C represents a control plane interface used for the NG2 reference point between the NG-RAN and the 5GC (5 Generation Core). NG-U represents the user plane interface used for the NG3 reference point between NG-RAN and 5GC.

The gNBs are interconnected through the Xn interface and connected to the 5GC through the NG interface. More specifically, the gNB is connected to an Access and Mobility Management Function (AMF) through the NG-C interface and to a User Plane Function (UPF) through the NG-U interface.

In the NR system of FIG. 2, multiple numerologies may be supported. Here, the numerology may be defined by a subcarrier spacing and a cyclic prefix (CP) overhead. In this case, the plurality of subcarrier intervals may be derived by scaling the basic subcarrier interval by an integer. Also, although it is assumed that very low subcarrier spacing is not used at very high carrier frequencies, the numerology used can be selected independently of the frequency band.

In addition, in the NR system, various frame structures according to a number of numerologies may be supported.

<NR Waveform, Pneumologic and Frame Structure>

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

Meanwhile, in NR, since the requirements for data rate, delay rate, coverage, etc. are different for each of the three scenarios described above, it is necessary to efficiently satisfy the requirements for each scenario through the 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.

Specifically, the NR transmission numerology is determined based on sub-carrier spacing and cyclic prefix (CP), and the μ value is used as an exponential value of 2 based on 15 kHz as shown in Table 1 below. is changed to

Subcarrier Spacing (kHz) Cyclic prefix Supported for data Supported for synch 15 Normal Yes Yes 30 Normal Yes Yes 60 Normal, Extended Yes No 120 Normal Yes Yes 240 Normal No Yes

As shown in Table 1 above, the NR numerology can be divided into five types according to the subcarrier spacing. This is different from the fact that the subcarrier interval of LTE, one of the 4G communication technologies, is fixed at 15 kHz. Specifically, in NR, subcarrier intervals used for data transmission are 15, 30, 60, and 120 kHz, and subcarrier intervals used for synchronization signal transmission are 15, 30, 120, 240 kHz. In addition, the extended CP is applied only to the 60 kHz subcarrier interval. On the other hand, as for the frame structure in NR, a frame having a length of 10 ms is defined, which is composed of 10 subframes having the same length of 1 ms. One frame can be divided into half frames of 5 ms, and each half frame includes 5 subframes. In the case of a 15 kHz subcarrier interval, one subframe consists of one slot, and each slot consists of 14 OFDM symbols.

<NR Physical Resources>

In relation to a physical resource in NR, an antenna port, a resource grid, a resource element, a resource block, a bandwidth part, etc. are considered do.

An antenna port is defined such that a channel on which a symbol on an antenna port is carried can be inferred from a channel on which another symbol on the same antenna port is carried. When the large-scale property of a channel on which a symbol on one antenna port is carried can be inferred from a channel on which a symbol on another antenna port is carried, the two antenna ports are QC/QCL (quasi co-located or It can be said that there is a quasi co-location) relationship. Here, the wide range characteristic includes one or more of delay spread, Doppler spread, frequency shift, average received power, and received timing.

3 is a diagram for explaining a resource grid supported by a radio access technology to which this embodiment can be applied.

Referring to FIG. 3 , in the resource grid, since NR supports a plurality of numerologies on the same carrier, a resource grid may exist according to each numerology. In addition, the resource grid may exist according to an antenna port, a subcarrier interval, and a transmission direction.

A resource block consists of 12 subcarriers, and is defined only in the frequency domain. In addition, a resource element is composed of one OFDM symbol and one subcarrier. Accordingly, as in FIG. 3 , the size of one resource block may vary according to the subcarrier interval. In addition, NR defines "Point A" serving as a common reference point for a resource block grid, a common resource block, a virtual resource block, and the like.

4 is a diagram for explaining a bandwidth part supported by a radio access technology to which the present embodiment can be applied.

In NR, unlike LTE in which the carrier bandwidth is fixed at 20 MHz, the maximum carrier bandwidth is set from 50 MHz to 400 MHz for each subcarrier interval. Therefore, it is not assumed that all terminals use all of these carrier bandwidths. Accordingly, in NR, as shown in FIG. 4, a bandwidth part (BWP) may be designated within the carrier bandwidth and used by the terminal. In addition, the bandwidth part is associated with one neurology and is composed of a subset of continuous common resource blocks, and may be dynamically activated according to time. Up to four bandwidth parts are configured in the terminal, respectively, in uplink and downlink, and data is transmitted/received using the activated bandwidth part at a given time.

In the case of a paired spectrum, the uplink and downlink bandwidth parts are set independently, and in the case of an unpaired spectrum, to prevent unnecessary frequency re-tunning between downlink and uplink operations For this purpose, the downlink and uplink bandwidth parts are set in pairs to share a center frequency.

<NR Initial Connection>

In NR, the terminal accesses the base station and performs a cell search and random access procedure in order to perform communication.

Cell search is a procedure in which the terminal synchronizes with the cell of the corresponding base station using a synchronization signal block (SSB) transmitted by the base station, obtains a physical layer cell ID, and obtains system information.

5 is a diagram exemplarily illustrating a synchronization signal block in a radio access technology to which the present embodiment can be applied.

Referring to FIG. 5, the SSB consists of a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS) occupying 1 symbol and 127 subcarriers, respectively, and a PBCH spanning 3 OFDM symbols and 240 subcarriers. .

The UE receives the SSB by monitoring the SSB in the time and frequency domains.

SSB can be transmitted up to 64 times in 5ms. A plurality of SSBs are transmitted using different transmission beams within 5 ms, and the UE performs detection on the assumption that SSBs are transmitted every 20 ms when viewed based on one specific beam used for transmission. The number of beams that can be used for SSB transmission within 5 ms time may increase as the frequency band increases. For example, up to 4 SSB beams can be transmitted in 3 GHz or less, and SSB can be transmitted using up to 8 different beams in a frequency band of 3 to 6 GHz and up to 64 different beams in a frequency band of 6 GHz or more.

Two SSBs are included in one slot, and the start symbol and the number of repetitions in the slot are determined according to the subcarrier interval.

On the other hand, the SSB is not transmitted at the center frequency of the carrier bandwidth, unlike the SS of the conventional LTE. That is, the SSB may be transmitted in a place other than the center of the system band, and a plurality of SSBs may be transmitted in the frequency domain when wideband operation is supported. Accordingly, the UE monitors the SSB using a synchronization raster that is a candidate frequency location for monitoring the SSB. The carrier raster and synchronization raster, which are the center frequency location information of the channel for initial access, are newly defined in NR. Compared to the carrier raster, the synchronization raster has a wider frequency interval than that of the carrier raster. can

The UE may acquire the MIB through the PBCH of the SSB. MIB (Master Information Block) includes minimum information for the terminal to receive the remaining system information (RMSI, Remaining Minimum System Information) broadcast by the network. In addition, the PBCH includes information on the position of the first DM-RS symbol in the time domain, information for the UE to monitor SIB1 (eg, SIB1 neurology information, information related to SIB1 CORESET, search space information, PDCCH related parameter information, etc.), offset information between the common resource block and the SSB (the position of the absolute SSB in the carrier is transmitted through SIB1), and the like. Here, the SIB1 neurology information is equally applied to some messages used in the random access procedure for accessing the base station after the UE completes the cell search procedure. For example, the neurology information of SIB1 may be applied to at least one of messages 1 to 4 for the random access procedure.

The aforementioned RMSI may mean System Information Block 1 (SIB1), and SIB1 is periodically broadcast (eg, 160 ms) in the cell. SIB1 includes information necessary for the UE to perform an initial random access procedure, and is periodically transmitted through the PDSCH. In order for the UE to receive SIB1, it must receive neurology information used for SIB1 transmission and CORESET (Control Resource Set) information used for scheduling SIB1 through the PBCH. The UE checks scheduling information for SIB1 by using SI-RNTI in CORESET, and acquires SIB1 on PDSCH according to the scheduling information. SIBs other than SIB1 may be transmitted periodically or may be transmitted according to the request of the terminal.

6 is a diagram for explaining a random access procedure in a radio access technology to which this embodiment can be applied.

Referring to FIG. 6 , upon completion of cell search, the terminal transmits a random access preamble for random access to the base station. The random access preamble is transmitted through the PRACH. Specifically, the random access preamble is transmitted to the base station through a PRACH consisting of continuous radio resources in a specific slot that is periodically repeated. In general, when a UE initially accesses a cell, a contention-based random access procedure is performed, and when random access is performed for beam failure recovery (BFR), a contention-free random access procedure is performed.

The terminal receives a random access response to the transmitted random access preamble. The random access response may include a random access preamble identifier (ID), a UL grant (uplink radio resource), a Temporary Cell - Radio Network Temporary Identifier (TC-RNTI), and a Time Advance Command (TAC). Since one random access response may include random access response information for one or more UEs, the random access preamble identifier may be included to inform which UE the included UL Grant, TC-RNTI, and TAC are valid. The random access preamble identifier may be an identifier for the random access preamble received by the base station. The TAC may be included as information for the UE to adjust uplink synchronization. The random access response may be indicated by a random access identifier on the PDCCH, that is, RA-RNTI (Random Access - Radio Network Temporary Identifier).

Upon receiving the valid random access response, the terminal processes information included in the random access response and performs scheduled transmission to the base station. For example, the UE applies the TAC and stores the TC-RNTI. In addition, data stored in the buffer of the terminal or newly generated data is transmitted to the base station by using the UL grant. In this case, information for identifying the terminal should be included.

Network Slicing

Network slicing provides network resources and network functions for each service by creating and providing End-to-End (E2E) resources spanning from a Radio Access Network (RAN) to a core network into one independent slice. Applied to 5G mobile communication that can apply properties such as isolation, customization, and independent management and orchestration to the RAN (Radio Access Network) and the core network of mobile communication It is a new concept to be

Communication technology combines with the development of technologies such as Network Function Virtualization (NFV) and Software Defined Network (SDN) to create a network slice optimized for the characteristics of each application in one huge network. developed in a way that constitutes

Network slice uses one physical network to create a logically separated network in E2E (End-to-End), including radio access, transmission, and 5G core equipment in the terminal, for various services with different characteristics. It provides a dedicated network specialized for that service. That is, the network slice is a technology that provides network resources and network functions necessary for the service requested by the terminal as one independent slice.

7 is a diagram for explaining a concept of a network slice according to an embodiment.

Referring to FIG. 7 , one network slice consists of an E2E logical network including a counterpart node (a counterpart terminal or a counterpart application server) from a terminal. A user can receive a service by accessing a network slice specialized for the application (eMBB, URLLC, MIoT, V2X, etc.) used. That is, the user's terminal may simultaneously access one or more network slices. Each slice may be identified by a slice/service type (SST) mapped to an expected network operation in terms of services and characteristics.

A mobile communication operator may allocate network resources suitable for a corresponding service for each slice or for each set of a specific slice. The network resource may refer to a logical resource or radio resource allocation provided by a network function (NF) or a network function (NF). A network slice instance (NSI) may be defined as a set of network function instances and required resources forming a deployed network slice.

In describing the embodiments of the present disclosure, a slice, a service, a network slice, a network service, an application slice, an application service, etc. may be mixed and used.

Random Access Procedure in Network Slicing

For uplink synchronization setup in NR, the UE transmits a random access preamble for a corresponding RACH occasion (RO) to a network node, and the network node receives the random access preamble and then communicates with the UE through TA (timing advance) estimation. It can be used to set the synchronization of The UE transmits the random access preamble at different times according to the delay time difference with the network node, and the network node detects a plurality of random access preambles, respectively, in various random access preamble formats and random access preamble monitoring period according to various scenarios. This is set

When network slicing is applied, the mobile communication operator may allocate network resources suitable for the corresponding service for each slice or for each set of specific slices, and the terminal may access one or more slices. To this end, the UE may perform a random access procedure for each independent slice. RAN slices constituting E2E (End-to-End) network slicing may be provided separately through frequency bands (eg, 3.5 GHz, 28 GHz) and/or time division, and are allocated for random access procedures for each slice. Frequency resources may also be different. Here, since each slice or services provided for each slice have different requirements for the random access procedure, a method for giving priority to the random access procedure is required.

Slice-based frequency resource allocation

An embodiment includes a method of allocating radio resources for random access differently according to each slice or service. Here, the radio resource may include a time or frequency resource. For example, a frequency resource for random access may be logically divided and operated for each slice by giving priority to each slice. Alternatively, frequency resources for random access may be logically divided and operated for each service by giving priority to each service (eg, eMBB, URLLC, mMTC, C-V2X, etc.). To this end, information indicating which random access or PRACH resource is mapped or allocated for each slice may be transmitted from the network node to the terminal. Alternatively, the communication system may be designed so that fixed or designated random access or PRACH resources exist for each slice. In this case, the UE and the network nodes may perform random access based on a specific set of random access resources in a specific slice without separate signaling.

In one aspect, different random access preambles may be used for each RAN slice (or for each service such as eMBB, URLLC, mMTC, C-V2X). That is, random access preambles used for each RAN slice or service can be distinguished from each other, and through this, the priority of the random access procedure can be adjusted. For example, it can be processed by setting a high priority for random access attempted in a RAN slice used for URLLC.

In one aspect, frequency and/or time resources may be separately configured for each random access preamble. Through this, it is possible to apply a priority for a random access procedure set differently for each slice or service. In relation to this, it should be noted that allocation of different frequency and/or time resources for each random access preamble may be applied even when a RAN slice is not applied.

In one aspect, a random access transmission power offset (RA Tx Power offset) value may be separately applied to each slice. The random access transmission power may be determined by applying a preset offset value to the received synchronization signal block (SSB) power. According to an aspect of the present invention, the random access transmission power offset value applied to each slice is different. By applying, priority can be applied when a random access procedure is attempted for each slice or service. For example, a random access procedure may be attempted with a higher transmission power (Tx power) for a URLLC service or a URLLC slice in which RAN slicing is applied, thereby improving the probability of success of the random access procedure. Furthermore, it is possible to more efficiently achieve low latency for the URLLC service. Also, for example, the random access transmission power offset may be set lower than that of URLLC for eMBB or mMTC, where the need for relatively fast access is alleviated compared to URLLC service.

Meanwhile, since various services can be simultaneously applied to one terminal as described above, according to an aspect of the present invention, different random access related parameters can be set for each RAN slice. Here, it should be noted that different parameters may be set for each slice or service in the random access procedure as well as in other communication procedures.

In one aspect, RAN slicing related information should be transmitted to the terminal. The RAN slicing-related information may be transmitted from the network node to the UE in the form of, for example, system information, an RRC message, MAC CE (Control Element), DCI (Downlink Control Information), and the like.

In one aspect, when RAN slicing is applied, frequency and time resources for random access may be separately used for each slice. In particular, if the frequency resource is set using, for example, the msg1-FDM and msg1-FrequencyStart values included in the PRACH configuration information, the msg1-FDM and msg1-FrequencyStart values are set differently for each slice. can Accordingly, the msg1-FDM and msg1-FrequencyStart values can be transmitted to the terminal through system information for each slice, an RRC message, and control signaling such as MAC CE or DCI. Time resources allocated for random access can also be set separately for each slice. For example, the random access resource for URLLC may be set in a shorter period than other services in time.

Although the above-described embodiments have been mainly described with respect to the application of each slice of the network slicing-based network for convenience of explanation, even if not otherwise specified, it is applied differently for each random access preamble on a network in which network slicing is not implemented, or each service It should be noted that (eg, eMBB, URLLC, mMTC, C-V2X, etc.) may be applied differently. For example, there may exist a form in which RAN slicing is applied to a specific base station and RAN slicing is not applied to a specific base station. Here, in the case of applying RAN slicing, the above-described embodiments may be applied for each RAN slice, and in the case of not applying RAN slicing, for example, by applying the above-described embodiments for each service, the random access procedure is different from each other. By processing in such a way that it is possible to set the priority of the random access procedure for each slice or each service.

On the other hand, for example, in a mobile communication system such as LTE or 5G system, a terminal performing handover may perform contention-free based random access. In one aspect, RAN slicing may be applied to both a serving cell and a target cell in which handover is performed. Here, when handover from a serving cell to which RAN slicing is applied to a target cell to which RAN slicing is applied and the UE performs contention-free random access in the target cell, information on RAN slice may be included in the handover parameter. Therefore, the terminal that has performed the handover can be stably and quickly connected to the target cell. Here, information on the RAN slice may be included in the handover message.

According to one aspect, RAN slicing may be applied to any one of a serving cell and a target cell in which handover is performed. Accordingly, handover may be performed from a cell to which a RAN slice is applied to a cell not using a RAN slice, and vice versa, that is, handover may be performed from a cell to which a RAN slice is not applied to a cell to which a RAN slice is applied. Even in this case, information related to the RAN slice may be included in the handover message, and the information related to the RAN slice may be considered for a contention-free based random access procedure. To this end, information on whether or not a RAN slice is applied in a specific cell or whether a RAN slice is not applied can be delivered to the terminal through, for example, system information, an RRC message, control signaling such as MAC CE, DCI, etc. .

In one aspect, the random access backoff (RA backoff) time may be set differently for each slice (or for each service). Here, the RA backoff time means a waiting time until the UE retry attempts when the random access attempt fails. As an example, the RA backoff time for the URLLC service (or URLLC slice) is greater than the RA backoff time for the eMBB service (or eMBB slice) or the RA backoff time for the mMTC (or Massive IoT) service (or mMTC slice). It can be set shorter. As another example, the RA backoff time for the mMTC (or Massive IoT) service (or mMTC slice) may be set longer than the RA backoff time for the eMBB service (or eMBB slice). That is, for a high-priority URLLC service (URLLC slicing), the UE can attempt a random access procedure based on a shorter RA backoff time, thereby improving the probability of success of the random access procedure for the URLLC service.

8 shows a terminal and a network node in which an embodiment of the present invention is implemented.

Referring to FIG. 8 , the terminal 1100 includes a processor 1110 , a memory 1120 , and a transceiver 1130 . The processor 1110 may be configured to implement the functions, processes, and/or methods described herein. The layers of the air interface protocol may be implemented in the processor 1110 .

The memory 1120 is connected to the processor 1110 and stores various information for driving the processor 1110 . The transceiver 1130 is connected to the processor 1110 to transmit a radio signal to the network node 1200 or receive a radio signal from the network node 1200 .

The network node 1200 includes a processor 1210 , a memory 1220 , and a transceiver 1230 . In this embodiment, the network node 1200 is a node of a non-terrestrial network, and may include an artificial satellite that performs a radio access procedure according to the present specification. Alternatively, in the present embodiment, the network node 1200 is a node of a terrestrial network, and may include a base station that performs a radio access procedure according to the present specification.

The processor 1210 may be configured to implement the functions, processes, and/or methods described herein. The layers of the air interface protocol may be implemented in the processor 1210 . The memory 1220 is connected to the processor 1210 and stores various information for driving the processor 1210 . The transceiver 1230 is connected to the processor 1210 to transmit a radio signal to the terminal 1100 or receive a radio signal from the terminal 1100 .

The processors 1110 and 1210 may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits, and/or data processing devices. The memories 1120 and 1220 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and/or other storage devices. The transceivers 1130 and 1230 may include a baseband circuit for processing a radio frequency signal. When the embodiment is implemented in software, the above-described technique may be implemented as a module (process, function, etc.) that performs the above-described function. The modules may be stored in the memories 1120 and 1220 and executed by the processors 1110 and 1210 . The memories 1120 and 1220 may be inside or outside the processors 1110 and 1210 , and may be connected to the processors 1110 and 1210 through various well-known means.

In the exemplary system described above, methods that can be implemented according to the features of the present invention described above have been described on the basis of a flowchart. For convenience, the methods have been described as a series of steps or blocks, but the claimed features of the invention are not limited to the order of steps or blocks, and some steps may occur in a different order or concurrently with other steps as described above. In addition, those skilled in the art will understand that the steps shown in the flowchart are not exhaustive and that other steps may be included or that one or more steps of the flowchart may be deleted without affecting the scope of the present invention.

Claims (24)

A method of performing random access of a terminal based on network slicing, comprising:
Receiving slicing-related information in which random access resources and parameters related to the priority of random access are individually set for each network slice from the base station; and
Including performing a random access procedure for the base station based on the slicing related information. The method of claim 1,
The slicing-related information is characterized in that received by being included in the system information or RRC message. The method of claim 1, wherein the random access procedure comprises:
transmitting a random access preamble to the base station based on the random access resource and the priority of the random access; and
Receiving a random access response message to the random access preamble from the base station, characterized in that it comprises the step of receiving. The method of claim 1,
The slicing-related information is characterized in that the random access transmit power offset value is individually set for each slice. 5. The method of claim 4,
A method, characterized in that the random access transmit power offset value of the network slice dedicated to the URLLC service (Ultra Reliable and Low Latency Communications) is greater than the random access transmit power offset value of the network slice that is not dedicated to the URLLC service. The method of claim 1,
The parameters related to the random access resource include msg1-FDM and msg1-FrequencyStart,
The method, characterized in that the msg1-FDM and the msg1-FrequencyStart are individually set for each network slice. The method of claim 1,
When the terminal performs handover from a serving cell to a target cell, the random access procedure is performed on a contention-free basis. 8. The method of claim 7,
The method, characterized in that the handover-related message of the base station includes at least a part of the slicing-related information. The method of claim 1,
The handover-related message of the base station, characterized in that it includes information on whether or not network slicing is applied. The method of claim 1,
The method, characterized in that the random access backoff time of the network slice dedicated to the URLLC service is smaller than the random access backoff time of the other network slices not dedicated to the URLLC service. The method of claim 1,
The method, characterized in that the random access backoff time of a network slice dedicated to the mMTC service (massive machine type communication) is greater than the random access backoff time of other network slices that are not dedicated to the mMTC service. A method of performing random access of a base station based on network slicing, comprising:
transmitting slicing-related information in which random access resources and parameters related to the priority of random access are individually set for each network slice to the terminal; and
Including the step of performing a random access procedure with the terminal based on the slicing-related information. 13. The method of claim 12,
The slicing-related information is characterized in that received by being included in the system information or RRC message. The method of claim 12, wherein the random access procedure comprises:
receiving a random access preamble from the terminal based on the random access resource and the priority of the random access; and
Method comprising the step of transmitting a random access response message to the random access preamble to the terminal. 13. The method of claim 12,
The slicing-related information is characterized in that the random access transmit power offset value is individually set for each slice. 16. The method of claim 15,
A method, characterized in that the random access transmit power offset value of the network slice dedicated to the URLLC service (Ultra Reliable and Low Latency Communications) is greater than the random access transmit power offset value of the network slice that is not dedicated to the URLLC service. 13. The method of claim 12,
The parameters related to the random access resource include msg1-FDM and msg1-FrequencyStart,
The method, characterized in that the msg1-FDM and the msg1-FrequencyStart are individually set for each network slice. 13. The method of claim 12,
When the terminal performs handover from a serving cell to a target cell, the random access procedure is performed on a contention-free basis. 19. The method of claim 18,
The method, characterized in that the handover-related message of the base station includes at least a part of the slicing-related information. 19. The method of claim 18,
The handover-related message of the base station, characterized in that it includes information on whether or not network slicing is applied. 13. The method of claim 12,
The method, characterized in that the random access backoff time of the network slice dedicated to the URLLC service is smaller than the random access backoff time of the other network slices not dedicated to the URLLC service. 13. The method of claim 12,
The method, characterized in that the random access backoff time of a network slice dedicated to the mMTC service (massive machine type communication) is greater than the random access backoff time of other network slices that are not dedicated to the mMTC service. A terminal that performs random access based on network slicing, comprising:
a transceiver for receiving slicing-related information in which random access resources and parameters related to priority of random access are individually set for each network slice from a base station, and performing a random access procedure for the base station based on the slicing-related information; and
A terminal comprising a processor for generating a random access preamble used in the random access procedure. A base station that performs random access based on network slicing, comprising:
a transceiver for transmitting slicing-related information in which random access resources and parameters related to the priority of random access are individually set for each network slice to the terminal, and performing a random access procedure with the terminal based on the slicing-related information; and
A base station comprising a processor for generating a random access response message used in the random access procedure.

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